One document matched: draft-ietf-rmt-pi-norm-revised-05.ps

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E(g/ietf/1id-)-.18 E(abstracts.txt.)93.6 417.6 Q
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2.5(services. NORM)93.6 592.8 R
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228 Q F0 10(.......................).32 G F2(9)10 E(2.3. Design T)82 240
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E(3. Conformance Statement)72 252 Q F0 10(........................)10.07
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E(5.5. Additional Protocol Mechanisms)82 516 Q F0 10
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528 Q(ime Collection)-.35 E F0 10(.................)12.36 G F2(52)5 E
(5.5.2. NORM Congestion Control Operation)92 540 Q F0 10
(.................)5.89 G F2(53)5 E(5.5.3. NORM Positi)92 552 Q .3 -.15
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(...............)3.78 G F2(60)5 E(5.5.4. Group Size Estimate)92 564 Q F0
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(.........................)7.36 G F2(66)5 E(8. Suggested Use)72 708 Q F0
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(9. Changes from RFC3940)72 720 Q F0 10(........................)9.22 G
F2(67)5 E F0(Adamson, et al.)72 768 Q(Expir)87.875 E
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G 2.5(ob)-2.5 G 2.5(ei)-2.5 G(nterpr)-2.5 E
(eted as described in BCP 14, RFC 21)-.18 E(19 [1].)-.55 E F1
(Statement of Intent)72 411.6 Q F0(This memo contains the definitions n\
ecessary to fully specify a Reliable Multicast T)93.6 427.2 Q(ransport)
-.9 E(pr)93.6 439.2 Q(otocol in accor)-.18 E(dance with RFC 2357.)-.18 E
(RFC3940 [10] contained a pr)5 E(evious description of the)-.18 E
(NORM Pr)93.6 451.2 Q(otocol specification described in this document.)
-.18 E(RF3940 was published in the)5 E("Experimental" category)93.6
463.2 Q 5(.I)-1.11 G 2.5(tw)-5 G
(as the stated intent of the RMT working gr)-2.5 E(oup to r)-.18 E
(e-submit)-.18 E(this specifications as an IETF Pr)93.6 475.2 Q
(oposed Standar)-.18 E 2.5(di)-.18 G 2.5(nd)-2.5 G(ue course.)-2.5 E
(This Pr)93.6 499.2 Q(oposed Standar)-.18 E 2.5(ds)-.18 G
(pecification is thus based on RFC3940 [10] and has been updated)-2.5 E
(accor)93.6 511.2 Q(ding to accumulated experience and gr)-.18 E
(owing pr)-.18 E(otocol maturity since the publication of)-.18 E 2.5
(RFC3940. Said)93.6 523.2 R(experience applies both to this specificati\
on itself and to congestion contr)2.5 E(ol)-.18 E(strategies r)93.6
535.2 Q(elated to the use of this specification.)-.18 E(The dif)93.6
559.2 Q(fer)-.18 E(ences between RFC3940 [10] and this document ar)-.18
E 2.5(el)-.18 G(isted in Section 9.)-2.5 E F1(1.1.)72 583.2 Q/F3 12
/Palatino-Bold@0 SF(NORM Delivery Service Model)5 E F0 2.5(AN)93.6 598.8
S(ORM pr)-2.5 E(otocol instance \()-.18 E/F4 10/Palatino-Italic@0 SF
(NormSession)A F0 2.5(\)i)C 2.5(sd)-2.5 G
(efined within the context of participants)-2.5 E
(communicating connectionless \(e.g., Internet Pr)93.6 610.8 Q
(otocol \(IP\) or User Datagram Pr)-.18 E(otocol)-.18 E
(\(UDP\)\) packets over a network using pr)93.6 622.8 Q
(e-determined addr)-.18 E(esses and host port numbers.)-.18 E(Generally)
93.6 634.8 Q 2.5(,t)-1.11 G
(he participants exchange packets using an IP multicast gr)-2.5 E
(oup addr)-.18 E(ess, but)-.18 E(unicast transport may also be establis\
hed or applied as an adjunct to multicast delivery)93.6 646.8 Q 5(.I)
-1.11 G(n)-5 E(the case of multicast, the participating)93.6 658.8 Q F4
(NormNodes)2.5 E F0(will communicate using a common IP)2.5 E
(multicast gr)93.6 670.8 Q(oup addr)-.18 E
(ess and port number that has been chosen via means outside the)-.18 E
(context of the given)93.6 682.8 Q F4(NormSession)2.5 E F0 5(.O)C
(ther IETF data format and pr)-5 E(otocol standar)-.18 E(ds exist that)
-.18 E(may be applied to describe and convey the r)93.6 694.8 Q(equir)
-.18 E(ed "a priori" information for a specific)-.18 E F4(NormSession)
93.6 706.8 Q F0(\(e.g., Session Description Pr)2.5 E(otocol \(SDP\) [1)
-.18 E(1], Session Announcement Pr)-.55 E(otocol)-.18 E
(\(SAP\) [12], etc.\).)93.6 718.8 Q(Adamson, et al.)72 768 Q(Expir)
87.875 E(es: 31 December 2007)-.18 E([Page 4])121.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(The NORM pr)93.6 120 Q(otocol \
design is principally driven by the assumption of a single sender)-.18 E
(transmitting bulk data content to a gr)93.6 132 Q(oup of r)-.18 E 2.5
(eceivers. However)-.18 F 2.5(,t)-.74 G(he pr)-2.5 E(otocol MA)-.18 E
2.5(Yo)-1.11 G(perate)-2.5 E
(with multiple senders within the context of a single)93.6 144 Q/F1 10
/Palatino-Italic@0 SF(NormSession)2.5 E F0 5(.I)C 2.5(ni)-5 G
(nitial implementations)-2.5 E(of this pr)93.6 156 Q(otocol, it is anti\
cipated that multiple senders will transmit independent of one)-.18 E
(another and r)93.6 168 Q
(eceivers will maintain state as necessary for each sender)-.18 E 5(.H)
-.74 G(owever)-5 E 2.5(,i)-.74 G 2.5(nf)-2.5 G(utur)-2.5 E(e)-.18 E
(versions of NORM, it is possible that some aspects of pr)93.6 180 Q
(otocol operation \(e.g., r)-.18 E(ound-trip)-.18 E
(time collection\) may pr)93.6 192 Q
(ovide for alternate modes allowing mor)-.18 E 2.5(ee)-.18 G -.18(ff)
-2.5 G(icient performance for).18 E(applications r)93.6 204 Q
(equiring multiple senders.)-.18 E(NORM pr)93.6 228 Q(ovides for thr)
-.18 E(ee types of bulk data content objects \()-.18 E F1(NormObjects)A
F0 2.5(\)t)C 2.5(ob)-2.5 G 2.5(er)-2.5 G(eliably)-2.68 E 2.5
(transported. These)93.6 240 R(types include:)2.5 E 25.17(1\) static)97
255.6 R(computer memory data content \()2.5 E/F2 10/Courier@0 SF
(NORM_OBJECT_DATA)A F0(type\),)2.5 E 25.17(2\) computer)97 271.2 R
(storage files \()2.5 E F2(NORM_OBJECT_FILE)A F0(type\), and)2.5 E 25.17
(3\) non-finite)97 286.8 R(str)2.5 E(eams of continuous data content \()
-.18 E F2(NORM_OBJECT_STREAM)A F0(type\).)2.5 E(The distinction between)
93.6 302.4 Q F2(NORM_OBJECT_DATA)2.5 E F0(and)2.5 E F2(NORM_OBJECT_FILE)
2.5 E F0(is simply to)2.5 E(pr)93.6 314.4 Q(ovide a "hint" to r)-.18 E
(eceivers in)-.18 E F1(NormSessions)2.5 E F0
(serving multiple types of content as to what)2.5 E
(type of storage should be allocated for r)93.6 326.4 Q
(eceived content \(i.e., memory or file storage\).)-.18 E(Other)5 E
(than that distinction, the two ar)93.6 338.4 Q 2.5(ei)-.18 G
(dentical, pr)-2.5 E(oviding for r)-.18 E
(eliable transport of finite \(but)-.18 E(potentially very lar)93.6
350.4 Q(ge\) units of content.)-.18 E
(These static data and file services ar)5 E 2.5(ea)-.18 G(nticipated to)
-2.5 E
(be useful for multicast-based cache applications with the ability to r)
93.6 362.4 Q(eliably pr)-.18 E(ovide)-.18 E(transmission of lar)93.6
374.4 Q(ge quantities of static data.)-.18 E
(Other types of static data/file delivery)5 E
(services might make use of these transport object types, too.)93.6
386.4 Q(The use of the)5 E F2(NORM_OBJECT_STREAM)93.6 398.4 Q F0
(type is at the application's discr)2.5 E
(etion and could be used to carry)-.18 E
(static data or file content also.)93.6 410.4 Q(The NORM r)5 E
(eliable str)-.18 E(eam service opens up additional)-.18 E
(possibilities such as serialized r)93.6 422.4 Q
(eliable messaging or other unbounded, per)-.18 E(haps dynamically)-.18
E(pr)93.6 434.4 Q(oduced content.)-.18 E(The)5 E F2(NORM_OBJECT_STREAM)
2.5 E F0(pr)2.5 E(ovides for r)-.18 E(eliable transport analogous to)
-.18 E(that of the T)93.6 446.4 Q(ransmission Contr)-.9 E(ol Pr)-.18 E
(otocol \(TCP\), although NORM r)-.18 E(eceivers will be able to)-.18 E
(begin r)93.6 458.4 Q(eceiving str)-.18 E
(eam content at any point in time.)-.18 E
(The applicability of this featur)5 E 2.5(ew)-.18 G(ill)-2.5 E
(depend upon the application.)93.6 470.4 Q(The NORM pr)93.6 494.4 Q
(otocol also allows for a small amount of "out-of-band" data \(sent as)
-.18 E F2(NORM_INFO)93.6 506.4 Q F0(messages\) to be attached to the da\
ta content objects transmitted by the sender)2.5 E(.)-.74 E(This r)93.6
518.4 Q(eadily-available "out-of-band" data allows multicast r)-.18 E
(eceivers to quickly and ef)-.18 E(ficiently)-.18 E(determine the natur)
93.6 530.4 Q 2.5(eo)-.18 G 2.5(ft)-2.5 G(he corr)-2.5 E
(esponding data, file, or str)-.18 E(eam bulk content being)-.18 E 2.5
(transmitted. This)93.6 542.4 R(allows application-level contr)2.5 E
(ol of the r)-.18 E(eceiver node's participation in the)-.18 E(curr)93.6
554.4 Q(ent transport activity)-.18 E 5(.T)-1.11 G
(his also allows the pr)-5 E(otocol to be flexible with minimal pr)-.18
E(e-)-.18 E(coor)93.6 566.4 Q(dination among senders and r)-.18 E 2.5
(eceivers. The)-.18 F F2(NORM_INFO)2.5 E F0(content is designed to be)
2.5 E(atomic in that its size MUST fit into the payload portion of a si\
ngle NORM message.)93.6 578.4 Q(NORM does _not_ pr)93.6 602.4 Q
(ovide for global or application-level identification of data content)
-.18 E(within in its message headers.)93.6 614.4 Q(Note the)5 E F2
(NORM_INFO)2.5 E F0(out-of-band data mechanism could be)2.5 E
(leveraged by the application for this purpose if desir)93.6 626.4 Q
(ed, or identification could alternatively)-.18 E
(be embedded within the data content.)93.6 638.4 Q
(NORM does identify transmitted content)5 E(\()93.6 650.4 Q F1
(NormObjects)A F0 2.5(\)w)C(ith transport identifiers that ar)-2.5 E 2.5
(ea)-.18 G(pplicable only while the sender is)-2.5 E
(transmitting and/or r)93.6 662.4 Q(epairing the given object.)-.18 E
(These transport data content identifiers)5 E(\()93.6 674.4 Q F1(NormT)A
(ransportIds)-1.11 E F0 2.5(\)a)C .36 -.18(re a)-2.5 H
(ssigned in a monotonically incr).18 E(easing fashion by each NORM)-.18
E(sender during the course of a)93.6 686.4 Q F1(NormSession)2.5 E F0 5
(.E)C(ach sender maintains its)-5 E F1(NormT)2.5 E(ransportId)-1.11 E F0
(assignments independently so that individual)93.6 698.4 Q F1
(NormObjects)2.5 E F0(may be uniquely identified)2.5 E(during transport\
 with the concatenation of the sender session-unique identifier)93.6
710.4 Q(\()93.6 722.4 Q F1(NormNodeId)A F0 2.5(\)a)C(nd the assigned)
-2.5 E F1(NormT)2.5 E(ransportId)-1.11 E F0 5(.T)C(he)-5 E F1(NormT)2.5
E(ransportId)-1.11 E F0 2.5(sa)C .36 -.18(re a)-2.5 H(ssigned fr).18 E
(om a)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(lar)93.6 120 Q
(ge, but fixed, numeric space in incr)-.18 E(easing or)-.18 E
(der and may be r)-.18 E(eassigned during long-lived)-.18 E 2.5
(sessions. The)93.6 132 R(NORM pr)2.5 E(otocol pr)-.18 E
(ovides mechanisms so that the sender application may)-.18 E
(terminate transmission of data content and inform the gr)93.6 144 Q
(oup of this in an ef)-.18 E(ficient manner)-.18 E(.)-.74 E
(Other similar pr)93.6 156 Q(otocol contr)-.18 E
(ol mechanisms \(e.g., session termination, r)-.18 E(eceiver)-.18 E
(synchr)93.6 168 Q(onization, etc.\) ar)-.18 E 2.5(es)-.18 G
(pecified so that r)-2.5 E(eliable multicast application variants may)
-.18 E(constr)93.6 180 Q(uct dif)-.08 E(fer)-.18 E
(ent, complete bulk transfer communication models to meet their goals.)
-.18 E 1.84 -.92(To s)93.6 204 T(ummarize, the NORM pr).92 E(otocol pr)
-.18 E(ovides r)-.18 E(eliable transport of dif)-.18 E(fer)-.18 E
(ent types of data)-.18 E
(content \(including potentially mixed types\).)93.6 216 Q
(The senders enqueue and transmit bulk content)5 E
(in the form of static data or files and/or non-finite, ongoing str)93.6
228 Q(eam types.)-.18 E(NORM senders)5 E(pr)93.6 240 Q(ovide for r)-.18
E(epair transmission of data and/or FEC content in r)-.18 E
(esponse to NACK messages)-.18 E -.18(re)93.6 252 S(ceived fr).18 E
(om the r)-.18 E(eceiver gr)-.18 E 2.5(oup. Mechanisms)-.18 F
(for "out-of-band" information and other)2.5 E(transport contr)93.6 264
Q(ol mechanisms ar)-.18 E 2.5(es)-.18 G
(pecified for use by applications to form complete r)-2.5 E(eliable)-.18
E(multicast solutions for dif)93.6 276 Q(fer)-.18 E(ent purposes.)-.18 E
/F1 10/Palatino-Bold@0 SF(1.2.)72 300 Q/F2 12/Palatino-Bold@0 SF
(NORM Scalability)5 E F0(Gr)93.6 315.6 Q
(oup communication scalability r)-.18 E(equir)-.18 E
(ements lead to adaptation of negative)-.18 E
(acknowledgment \(NACK\) based pr)93.6 327.6 Q
(otocol schemes when feedback for r)-.18 E(eliability is r)-.18 E(equir)
-.18 E(ed)-.18 E 2.5([13]. NORM)93.6 339.6 R(is a pr)2.5 E
(otocol center)-.18 E(ed ar)-.18 E(ound the use of selective NACKs to r)
-.18 E(equest r)-.18 E(epairs of)-.18 E(missing data.)93.6 351.6 Q
(NORM pr)5 E(ovides for the use of packet-level forwar)-.18 E 2.5(de)
-.18 G(rr)-2.5 E(or corr)-.18 E(ection \(FEC\))-.18 E(techniques for ef)
93.6 363.6 Q(ficient multicast r)-.18 E(epair and optional pr)-.18 E
(oactive transmission r)-.18 E(obustness [14].)-.18 E(FEC-based r)93.6
375.6 Q(epair can be used to gr)-.18 E(eatly r)-.18 E
(educe the quantity of r)-.18 E(eliable multicast r)-.18 E(epair)-.18 E
-.18(re)93.6 387.6 S(quests and r).18 E
(epair transmissions [15] in a NACK-oriented pr)-.18 E 2.5(otocol. The)
-.18 F(principal factor in)2.5 E
(NORM scalability is the volume of feedback traf)93.6 399.6 Q
(fic generated by the r)-.18 E(eceiver set to facilitate)-.18 E -.18(re)
93.6 411.6 S(liability and congestion contr).18 E 2.5(ol. NORM)-.18 F
(uses pr)2.5 E(obabilistic suppr)-.18 E(ession of r)-.18 E(edundant)-.18
E(feedback based on exponentially distributed random backof)93.6 423.6 Q
2.5(ft)-.18 G 2.5(imers. The)-2.5 F(performance of)2.5 E
(this type of suppr)93.6 435.6 Q(ession r)-.18 E
(elative to other techniques is described in [16].)-.18 E(NORM)5 E
(dynamically measur)93.6 447.6 Q(es the gr)-.18 E(oup's r)-.18 E
(oundtrip timing status to set its suppr)-.18 E(ession and other)-.18 E
(pr)93.6 459.6 Q(otocol timers.)-.18 E
(This allows NORM to scale well while maintaining r)5 E
(eliable data delivery)-.18 E(transport with low latency r)93.6 471.6 Q
(elative to the network topology over which it is operating.)-.18 E
(Feedback messages can be either multicast to the gr)93.6 495.6 Q
(oup at lar)-.18 E(ge or sent via unicast r)-.18 E(outing to)-.18 E
(the sender)93.6 507.6 Q 5(.I)-.74 G 2.5(nt)-5 G(he case of unicast fee\
dback, the sender "advertises" the feedback state to the)-2.5 E(gr)93.6
519.6 Q(oup to facilitate feedback suppr)-.18 E 2.5(ession. In)-.18 F
(typical Internet envir)2.5 E(onments, it is expected that)-.18 E
(the NORM pr)93.6 531.6 Q(otocol will r)-.18 E(eadily scale to gr)-.18 E
(oup sizes on the or)-.18 E(der of tens of thousands of)-.18 E -.18(re)
93.6 543.6 S 2.5(ceivers. A).18 F
(study of the quantity of feedback for this type of pr)2.5 E
(otocol is described in [17].)-.18 E(NORM is able to operate with a sma\
ller amount of feedback than a single TCP connection,)93.6 555.6 Q
(even with r)93.6 567.6 Q(elatively lar)-.18 E(ge numbers of r)-.18 E
2.5(eceivers. Thus,)-.18 F(depending upon the network)2.5 E(topology)
93.6 579.6 Q 2.5(,i)-1.11 G 2.5(ti)-2.5 G 2.5(sp)-2.5 G
(ossible that NORM may scale to lar)-2.5 E(ger gr)-.18 E(oup sizes.)-.18
E -.55(Wi)5 G(th r).55 E(espect to computer)-.18 E -.18(re)93.6 591.6 S
(sour).18 E(ce usage, the NORM pr)-.18 E(otocol does _not_ r)-.18 E
(equir)-.18 E 2.5(et)-.18 G(hat state be kept on all r)-2.5 E
(eceivers in)-.18 E(the gr)93.6 603.6 Q 2.5(oup. NORM)-.18 F
(senders maintain state only for r)2.5 E(eceivers pr)-.18 E
(oviding explicit congestion)-.18 E(contr)93.6 615.6 Q(ol feedback.)-.18
E(NORM r)5 E(eceivers must maintain state for each active sender)-.18 E
5(.T)-.74 G(his may)-5 E
(constrain the number of simultaneous senders in some uses of NORM.)93.6
627.6 Q F1(1.3.)72 651.6 Q F2
(Environmental Requirements and Considerations)5 E F0(All of the envir)
93.6 667.2 Q(onmental r)-.18 E(equir)-.18 E
(ements and considerations that apply to the RMT NORM)-.18 E(Building B\
lock [3], the RMT FEC Building Block [4], and the RMT TCP-Friendly Mult\
icast)93.6 679.2 Q(Congestion Contr)93.6 691.2 Q
(ol \(TFMCC\) Building Block [5], also apply to the NORM pr)-.18 E
(otocol.)-.18 E(The NORM pr)93.6 715.2 Q
(otocol SHALL be capable of operating in an end-to-end fashion with no)
-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(assistance fr)93.6 120 Q
(om intermediate systems beyond basic IP multicast gr)-.18 E
(oup management, r)-.18 E(outing,)-.18 E(and forwar)93.6 132 Q
(ding services.)-.18 E(While the techniques utilized in NORM ar)5 E 2.5
(ep)-.18 G(rincipally applicable)-2.5 E(to "flat" end-to-end IP multica\
st topologies, they could also be applied in the sub-levels of)93.6 144
Q(hierar)93.6 156 Q(chical \(e.g., tr)-.18 E
(ee-based\) multicast distribution if so desir)-.18 E 2.5(ed. NORM)-.18
F(can make use of)2.5 E -.18(re)93.6 168 S(cipr).18 E
(ocal \(among senders and r)-.18 E
(eceivers\) multicast communication under the Any-Sour)-.18 E(ce)-.18 E
(Multicast \(ASM\) model defined in RFC 1)93.6 180 Q -.55(11)-.55 G 2.5
(2[).55 G(2], but SHALL also be capable of scalable)-2.5 E
(operation in asymmetric topologies such as Sour)93.6 192 Q
(ce Specific Multicast \(SSM\) [18] wher)-.18 E 2.5(et)-.18 G(her)-2.5 E
(e)-.18 E(may only be unicast r)93.6 204 Q(outing service fr)-.18 E
(om the r)-.18 E(eceivers to the sender\(s\).)-.18 E
(NORM is compatible with IPv4 and IPv6.)93.6 228 Q(Additionally)5 E 2.5
(,N)-1.11 G(ORM may be used with networks)-2.5 E(employing Network Addr)
93.6 240 Q(ess T)-.18 E(ranslation \(NA)-.9 E(T\) pr)-.74 E
(oviding the NA)-.18 E 2.5(Td)-.74 G(evice supports IP)-2.5 E
(multicast and/or can cache UDP traf)93.6 252 Q(fic sour)-.18 E
(ce port numbers for r)-.18 E(emapping feedback traf)-.18 E(fic)-.18 E
(fr)93.6 264 Q(om r)-.18 E(eceivers to the sender\(s\).)-.18 E/F1 10
/Palatino-Bold@0 SF(2.)72 288 Q/F2 13/Palatino-Bold@0 SF
(Architecture Definition)5 E F0(A)93.6 303.6 Q/F3 10/Palatino-Italic@0
SF(NormSession)2.5 E F0(is comprised of participants \()2.5 E F3
(NormNodes)A F0 2.5(\)a)C(cting as senders and/or r)-2.5 E(eceivers.)
-.18 E(NORM senders transmit data content in the form of)93.6 315.6 Q F3
(NormObjects)2.5 E F0(to the session destination)2.5 E(addr)93.6 327.6 Q
(ess and the NORM r)-.18 E(eceivers attempt to r)-.18 E(eliably r)-.18 E
(eceive the transmitted content using)-.18 E
(negative acknowledgments to r)93.6 339.6 Q(equest r)-.18 E(epair)-.18 E
5(.E)-.74 G(ach)-5 E F3(NormNode)2.5 E F0(within a)2.5 E F3(NormSession)
2.5 E F0(is)2.5 E(assumed to have a pr)93.6 351.6 Q
(eselected unique 32-bit identifier \()-.18 E F3(NormNodeId)A F0(\).)A
F3(NormNodes)5 E F0(MUST)2.5 E
(have uniquely assigned identifiers within a single)93.6 363.6 Q F3
(NormSession)2.5 E F0(to distinguish between)2.5 E
(possible multiple senders and to distinguish feedback information fr)
93.6 375.6 Q(om dif)-.18 E(fer)-.18 E(ent r)-.18 E(eceivers.)-.18 E
(Ther)93.6 387.6 Q 2.5(ea)-.18 G .36 -.18(re t)-2.5 H(wo r).18 E
(eserved)-.18 E F3(NormNodeId)2.5 E F0 2.5(values. A)2.5 F(value of)2.5
E/F4 10/Courier@0 SF(0x00000000)2.5 E F0(is consider)2.5 E(ed an)-.18 E
(invalid)93.6 399.6 Q F3(NormNodeId)2.5 E F0(value and a value of)2.5 E
F4(0xffffffff)2.5 E F0(is a "wildcar)2.5 E(d")-.18 E F3(NormNodeId)2.5 E
F0 5(.W)C(hile)-5 E(the pr)93.6 411.6 Q(otocol does not pr)-.18 E
(eclude multiple sender nodes concurr)-.18 E
(ently transmitting within the)-.18 E(context of a single NORM session \
\(i.e., many- to-many operation\), any type of interactive)93.6 423.6 Q
(coor)93.6 435.6 Q(dination among NORM senders is assumed to be contr)
-.18 E(olled by the application or higher)-.18 E(pr)93.6 447.6 Q
(otocol layer)-.18 E 5(.T)-.74 G(her)-5 E 2.5(ea)-.18 G .36 -.18(re s)
-2.5 H(ome optional mechanisms specified in this document that can be)
.18 E(leveraged for such application layer coor)93.6 459.6 Q(dination.)
-.18 E(As pr)93.6 483.6 Q(eviously noted, NORM allows for r)-.18 E
(eliable transmission of thr)-.18 E(ee dif)-.18 E(fer)-.18 E
(ent basic types of)-.18 E(data content.)93.6 495.6 Q(The first type is)
5 E F4(NORM_OBJECT_DATA)2.5 E F0 2.5(,w)C
(hich is used for static, persistent)-2.5 E
(blocks of data content maintained in the sender)93.6 507.6 Q
('s application memory storage.).74 E(The second)5 E(type is)93.6 519.6
Q F4(NORM_OBJECT_FILE)2.5 E F0 2.5(,w)C(hich corr)-2.5 E
(esponds to data stor)-.18 E(ed in the sender)-.18 E('s non-volatile).74
E(file system.)93.6 531.6 Q(The)5 E F4(NORM_OBJECT_DATA)2.5 E F0(and)2.5
E F4(NORM_OBJECT_FILE)2.5 E F0(types both r)2.5 E(epr)-.18 E(esent)-.18
E(")93.6 543.6 Q F3(NormObjects)A F0 2.5("o)C 2.5(ff)-2.5 G
(inite but potentially very lar)-2.5 E(ge size.)-.18 E(The thir)5 E 2.5
(dt)-.18 G(ype of data content is)-2.5 E F4(NORM_OBJECT_STREAM)93.6
555.6 Q F0 2.5(,w)C(hich corr)-2.5 E
(esponds to an ongoing transmission of undefined)-.18 E 2.5
(length. This)93.6 567.6 R(is analogous to the r)2.5 E(eliable str)-.18
E(eam service pr)-.18 E(ovide by TCP for unicast data)-.18 E 2.5
(transport. The)93.6 579.6 R(format of the str)2.5 E
(eam content is application-defined and may be byte or)-.18 E
(message oriented.)93.6 591.6 Q(The NORM pr)5 E(otocol pr)-.18 E
(ovides for "flushing" of the str)-.18 E(eam to expedite)-.18 E
(delivery or possibly enfor)93.6 603.6 Q
(ce application message boundaries.)-.18 E(NORM pr)5 E(otocol)-.18 E
(implementations may of)93.6 615.6 Q(fer either \(or both\) in-or)-.18 E
(der delivery of the str)-.18 E(eam data to the r)-.18 E(eceive)-.18 E
(application or out-of-or)93.6 627.6 Q(der \(mor)-.18 E 2.5(ei)-.18 G
(mmediate\) delivery of r)-2.5 E(eceived segments of the str)-.18 E
(eam to)-.18 E(the r)93.6 639.6 Q(eceiver application.)-.18 E
(In either case, NORM sender and r)5 E(eceiver implementations)-.18 E
(pr)93.6 651.6 Q(ovide buf)-.18 E(fering to facilitate r)-.18 E
(epair of the str)-.18 E(eam as it is transported.)-.18 E(All)93.6 675.6
Q F3(NormObjects)2.5 E F0(ar)2.5 E 2.5(el)-.18 G
(ogically segmented into FEC coding blocks and symbols for)-2.5 E
(transmission by the sender)93.6 687.6 Q 5(.I)-.74 G 2.5(nN)-5 G
(ORM, an FEC encoding symbol dir)-2.5 E(ectly corr)-.18 E
(esponds to the)-.18 E(payload of)93.6 699.6 Q F4(NORM_DATA)2.5 E F0
(messages or "segment".)2.5 E(Note that when systematic FEC codes ar)5 E
(e)-.18 E(used, the payload of)93.6 711.6 Q F4(NORM_DATA)2.5 E F0
(messages sent for the first portion of a FEC encoding block)2.5 E(ar)
93.6 723.6 Q 2.5(es)-.18 G(our)-2.5 E
(ce symbols \(actual segments of original user data\), while the r)-.18
E(emaining symbols for)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(the block consist of parity symbols generated by FEC encoding.)93.6 120
Q(These parity symbols ar)5 E(e)-.18 E(generally sent in r)93.6 132 Q
(esponse to r)-.18 E(epair r)-.18 E
(equests, but some number may be sent pr)-.18 E(oactively at)-.18 E
(the end each encoding block to incr)93.6 144 Q(ease the r)-.18 E
(obustness of transmission.)-.18 E(When non-)5 E
(systematic FEC codes ar)93.6 156 Q 2.5(eu)-.18 G
(sed, all symbols sent consist of FEC encoding parity content.)-2.5 E
(In)5 E(this case, the r)93.6 168 Q(eceiver must r)-.18 E(eceive a suf)
-.18 E(ficient number of symbols to r)-.18 E(econstr)-.18 E
(uct \(via FEC)-.08 E
(decoding\) the original user data for the given block.)93.6 180 Q
(In this document, the terms "symbol")5 E(and "segment" ar)93.6 192 Q
2.5(eu)-.18 G(sed inter)-2.5 E(changeably)-.18 E(.)-1.11 E -.9(Tr)93.6
216 S(ansmitted).9 E/F1 10/Palatino-Italic@0 SF(NormObjects)2.5 E F0(ar)
2.5 E 2.5(et)-.18 G(emporarily yet uniquely identified within the)-2.5 E
F1(NormSession)2.5 E F0(context using the given sender)93.6 228 Q('s).74
E F1(NormNodeId)2.5 E F0(,)A F1(NormInstanceId)2.5 E F0 2.5(,a)C
(nd a temporary)-2.5 E F1(NormObjectT)93.6 240 Q(ransportId)-1.11 E F0 5
(.D)C(epending upon the implementation, individual NORM senders)-5 E
(may manage their)93.6 252 Q F1(NormInstanceIds)2.5 E F0(independently)
2.5 E 2.5(,o)-1.11 G 2.5(rac)-2.5 G(ommon)-2.5 E F1(NormInstanceId)2.5 E
F0(may be)2.5 E(agr)93.6 264 Q(eed upon for all participating nodes wit\
hin a session if needed as a session identifier)-.18 E(.)-.74 E(NORM)
93.6 276 Q F1(NormObjectT)2.5 E(ransportId)-1.11 E F0
(data content identifiers ar)2.5 E 2.5(es)-.18 G(ender)-2.5 E
(-assigned and applicable)-.18 E(and valid only during a)93.6 288 Q F1
(NormObject)2.5 E F0
('s actual _transport_ \(i.e., for as long as the sender is)A
(transmitting and pr)93.6 300 Q(oviding r)-.18 E(epair of the indicated)
-.18 E F1(NormObject)2.5 E F0 2.5(\). For)B 2.5(al)2.5 G
(ong-lived session, the)-2.5 E F1(NormObjectT)93.6 312 Q(ransportId)
-1.11 E F0(field can wrap and pr)2.5 E
(eviously-used identifiers may be r)-.18 E 2.5(e-used. Note)-.18 F(that\
 globally unique identification of transported data content is not pr)
93.6 324 Q(ovided by NORM)-.18 E(and, if r)93.6 336 Q(equir)-.18 E
(ed, must be managed by the NORM application.)-.18 E
(The individual segments or)5 E(symbols of the)93.6 348 Q F1(NormObject)
2.5 E F0(ar)2.5 E 2.5(ef)-.18 G
(urther identified with FEC payload identifiers which include)-2.5 E
(coding block and symbol identifiers.)93.6 360 Q(These ar)5 E 2.5(ed)
-.18 G(iscussed in detail later in this document.)-2.5 E/F2 10
/Palatino-Bold@0 SF(2.1.)72 384 Q/F3 12/Palatino-Bold@0 SF
(Protocol Operation Overview)5 E F0 2.5(AN)93.6 399.6 S
(ORM sender primarily generates messages of type)-2.5 E/F4 10/Courier@0
SF(NORM_DATA)2.5 E F0 5(.T)C(hese messages carry)-5 E
(original data segments or FEC symbols and r)93.6 411.6 Q
(epair segments/symbols for the bulk data/file)-.18 E(or str)93.6 423.6
Q(eam)-.18 E F1(NormObjects)2.5 E F0(being transferr)2.5 E 2.5(ed. By)
-.18 F(default, r)2.5 E(edundant FEC symbols ar)-.18 E 2.5(es)-.18 G
(ent only)-2.5 E(in r)93.6 435.6 Q(esponse to r)-.18 E(eceiver r)-.18 E
(epair r)-.18 E
(equests \(NACKs\) and thus normally little or no additional)-.18 E
(transmission over)93.6 447.6 Q(head is imposed due to FEC encoding.)
-.18 E(However)5 E 2.5(,t)-.74 G(he NORM)-2.5 E(implementation MA)93.6
459.6 Q 2.5(Yb)-1.11 G 2.5(eo)-2.5 G(ptionally configur)-2.5 E(ed to pr)
-.18 E(oactively transmit some amount of)-.18 E -.18(re)93.6 471.6 S(du\
ndant FEC symbols along with the original content to potentially enhanc\
e performance).18 E(\(e.g., impr)93.6 483.6 Q
(oved delay\) at the cost of additional transmission over)-.18 E 2.5
(head. This)-.18 F(option may be)2.5 E
(sensible for certain network conditions and can allow for r)93.6 495.6
Q(obust, asymmetric multicast \(e.g.,)-.18 E(unidir)93.6 507.6 Q
(ectional r)-.18 E(outing, satellite, cable\) [19] with r)-.18 E
(educed r)-.18 E(eceiver feedback, or)-.18 E 2.5(,i)-.74 G 2.5(ns)-2.5 G
(ome cases,)-2.5 E(no feedback.)93.6 519.6 Q 2.5(As)93.6 543.6 S
(ender message of type)-2.5 E F4(NORM_INFO)2.5 E F0
(is also defined and is used to carry OPTIONAL "out-)2.5 E
(of-band" context information for a given transport object.)93.6 555.6 Q
2.5(As)5 G(ingle)-2.5 E F4(NORM_INFO)2.5 E F0(message can)2.5 E
(be associated with a)93.6 567.6 Q F1(NormObject)2.5 E F0 5(.B)C
(ecause of its atomic natur)-5 E(e, missing)-.18 E F4(NORM_INFO)2.5 E F0
(messages can be NACKed and r)93.6 579.6 Q(epair)-.18 E
(ed with a slightly lower delay pr)-.18 E(ocess than NORM's)-.18 E
(general FEC-encoded data content.)93.6 591.6 Q F4(NORM_INFO)5 E F0
(may serve special purposes for some bulk)2.5 E(transfer)93.6 603.6 Q
2.5(,r)-.74 G(eliable multicast applications wher)-2.68 E 2.5(er)-.18 G
(eceivers join the gr)-2.68 E(oup mid-str)-.18 E(eam and need)-.18 E
(to ascertain contextual information on the curr)93.6 615.6 Q
(ent content being transmitted.)-.18 E(The NACK)5 E(pr)93.6 627.6 Q
(ocess for)-.18 E F4(NORM_INFO)2.5 E F0(will be described later)2.5 E 5
(.W)-.74 G(hen the)-5 E F4(NORM_INFO)2.5 E F0(message type is used,)2.5
E(its transmission should pr)93.6 639.6 Q(ecede transmission of any)-.18
E F4(NORM_DATA)2.5 E F0(message for the associated)2.5 E F1(NormObject)
93.6 651.6 Q F0(.)A(The sender also generates messages of type)93.6
675.6 Q F4(NORM_CMD)2.5 E F0(to assist in certain pr)2.5 E(otocol)-.18 E
(operations such as congestion contr)93.6 687.6 Q
(ol, end-of-transmission flushing, r)-.18 E(ound trip time)-.18 E
(estimation, r)93.6 699.6 Q(eceiver synchr)-.18 E
(onization, and optional positive acknowledgment r)-.18 E(equests or)
-.18 E(application defined commands.)93.6 711.6 Q(The transmission of)5
E F4(NORM_CMD)2.5 E F0(messages fr)2.5 E(om the sender is)-.18 E
(accomplished by one of thr)93.6 723.6 Q(ee dif)-.18 E(fer)-.18 E
(ent pr)-.18 E(ocedur)-.18 E 2.5(es. These)-.18 F(pr)2.5 E(ocedur)-.18 E
(es ar)-.18 E(e: single, best ef)-.18 E(fort)-.18 E(Adamson, et al.)72
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(unr)93.6 120 Q
(eliable transmission of the command; r)-.18 E(epeated r)-.18 E
(edundant transmissions of the)-.18 E
(command; and positively-acknowledged commands.)93.6 132 Q
(The transmission technique used for a)5 E
(given command depends upon the function of the command.)93.6 144 Q
(Several cor)5 E 2.5(ec)-.18 G(ommands ar)-2.5 E(e)-.18 E
(defined for basic pr)93.6 156 Q(otocol operation.)-.18 E(Additionally)5
E 2.5(,i)-1.11 G(mplementations MA)-2.5 E 2.5(Yw)-1.11 G
(ish to consider)-2.5 E(pr)93.6 168 Q(oviding the OPTIONAL application-\
defined commands that can take advantage of the)-.18 E
(transmission methodologies available for commands.)93.6 180 Q
(This allows for application-level)5 E(session management mechanisms th\
at can make use of information available to the)93.6 192 Q
(underlying NORM pr)93.6 204 Q(otocol engine \(e.g., r)-.18 E
(ound-trip timing, transmission rate, etc.\).)-.18 E(A)5 E
(notable distinction between)93.6 216 Q/F1 10/Courier@0 SF(NORM_DATA)2.5
E F0(message and some)2.5 E F1(NORM_CMD)2.5 E F0(message)2.5 E
(transmissions is that typically a r)93.6 228 Q
(eceiver will need to allocate r)-.18 E(esour)-.18 E(ces to manage r)
-.18 E(eliable)-.18 E -.18(re)93.6 240 S(ception when).18 E F1
(NORM_DATA)2.5 E F0(messages ar)5 E 2.5(er)-.18 G 2.5(eceived. However)
-2.68 F(some)2.5 E F1(NORM_CMD)2.5 E F0(messages)2.5 E
(may be completely atomic and no specific state may need to be kept.)
93.6 252 Q(Thus, for session)5 E(management or other purposes it is pos\
sible that even participants acting principally as data)93.6 264 Q -.18
(re)93.6 276 S(ceivers MA).18 E 2.5(Yt)-1.11 G(ransmit)-2.5 E F1
(NORM_CMD)2.5 E F0 2.5(messages. However)2.5 F 2.5(,i)-.74 G 2.5(ti)-2.5
G 2.5(sR)-2.5 G(ECOMMENDED that this is)-2.5 E(not done within the cont\
ext of the NORM multicast session unless congestion contr)93.6 288 Q
(ol is)-.18 E(addr)93.6 300 Q 2.5(essed. For)-.18 F(example, many r)2.5
E(eceiver nodes transmitting)-.18 E F1(NORM_CMD)2.5 E F0(messages)2.5 E
(simultaneously can cause congestion for the destination\(s\).)93.6 312
Q(All sender transmissions ar)93.6 336 Q 2.5(es)-.18 G
(ubject to rate contr)-2.5 E
(ol governed by a peak transmission rate set)-.18 E
(for each participant by the application.)93.6 348 Q
(This can be used to limit the quantity of multicast)5 E
(data transmitted by the gr)93.6 360 Q 2.5(oup. When)-.18 F
(NORM's congestion contr)2.5 E(ol algorithm is enabled the)-.18 E
(rate for senders is automatically adjusted.)93.6 372 Q
(In some networks, it may be desirable to establish)5 E(minimum and max\
imum bounds for the rate adjustment depending upon the application)93.6
384 Q(even when dynamic congestion contr)93.6 396 Q(ol is enabled.)-.18
E(However)5 E 2.5(,i)-.74 G 2.5(nt)-2.5 G(he case of the general)-2.5 E
(Internet, congestion contr)93.6 408 Q
(ol policy SHALL be observed that is compatible with coexistent)-.18 E
(TCP flows.)93.6 420 Q(NORM r)93.6 444 Q
(eceivers generate messages of type)-.18 E F1(NORM_NACK)2.5 E F0(or)2.5
E F1(NORM_ACK)2.5 E F0(in r)2.5 E(esponse to)-.18 E
(transmissions of data and commands fr)93.6 456 Q(om a sender)-.18 E 5
(.T)-.74 G(he)-5 E F1(NORM_NACK)2.5 E F0(messages ar)2.5 E(e)-.18 E
(generated to r)93.6 468 Q(equest r)-.18 E
(epair of detected data transmission losses.)-.18 E
(Receivers generally detect)5 E
(losses by tracking the sequence of transmission fr)93.6 480 Q
(om a sender)-.18 E 5(.S)-.74 G(equencing information is)-5 E(embedded \
in the transmitted data packets and end-of-transmission commands fr)93.6
492 Q(om the)-.18 E(sender)93.6 504 Q(.)-.74 E F1(NORM_ACK)5 E F0
(messages ar)2.5 E 2.5(eg)-.18 G(enerated in r)-2.5 E
(esponse to certain commands transmitted by)-.18 E(the sender)93.6 516 Q
5(.I)-.74 G 2.5(nt)-5 G(he general \(and most scalable\) pr)-2.5 E
(otocol mode,)-.18 E F1(NORM_ACK)2.5 E F0(messages ar)2.5 E 2.5(es)-.18
G(ent)-2.5 E(only in r)93.6 528 Q(esponse to congestion contr)-.18 E
(ol commands fr)-.18 E(om the sender)-.18 E 5(.T)-.74 G
(he feedback volume of)-5 E(these congestion contr)93.6 540 Q(ol)-.18 E
F1(NORM_ACK)2.5 E F0(messages is contr)2.5 E(olled using the same timer)
-.18 E(-based)-.18 E(pr)93.6 552 Q(obabilistic suppr)-.18 E
(ession techniques as for)-.18 E F1(NORM_NACK)2.5 E F0
(messages to avoid feedback)2.5 E 2.5(implosion. In)93.6 564 R(or)2.5 E
(der to meet potential application r)-.18 E(equir)-.18 E
(ements for positive)-.18 E(acknowledgment fr)93.6 576 Q(om r)-.18 E
(eceivers, other)-.18 E F1(NORM_ACK)2.5 E F0(messages ar)2.5 E 2.5(ed)
-.18 G(efined and available for)-2.5 E(use.)93.6 588 Q/F2 10
/Palatino-Bold@0 SF(2.2.)72 612 Q/F3 12/Palatino-Bold@0 SF
(Protocol Building Blocks)5 E F0(The operation of the NORM pr)93.6 627.6
Q(otocol is based primarily upon the concepts pr)-.18 E(esented in the)
-.18 E
(Nack-Oriented Reliable Multicast \(NORM\) Building Block document [3].)
93.6 639.6 Q(This includes the)5 E(basic NORM ar)93.6 651.6 Q(chitectur)
-.18 E 2.5(ea)-.18 G(nd the data transmission, r)-2.5 E(epair)-.18 E 2.5
(,a)-.74 G(nd feedback strategies)-2.5 E(discussed in that document.)
93.6 663.6 Q(Additional r)5 E(eliable multicast building blocks ar)-.18
E 2.5(ea)-.18 G(pplied in)-2.5 E(cr)93.6 675.6 Q
(eating the full NORM pr)-.18 E(otocol instantiation [20].)-.18 E
(NORM also makes use of Forwar)5 E 2.5(dE)-.18 G(rr)-2.5 E(or)-.18 E
(Corr)93.6 687.6 Q(ection encoding techniques for r)-.18 E
(epair messaging and optional transmission r)-.18 E(obustness)-.18 E
(as described in [14].)93.6 699.6 Q
(NORM uses the FEC Payload ID as specified by the FEC Building Block)5 E
(Document [4].)93.6 711.6 Q(Additionally)5 E 2.5(,f)-1.11 G
(or congestion contr)-2.5 E(ol, this document includes a baseline)-.18 E
(congestion contr)93.6 723.6 Q
(ol mechanism \(NORM-CC\) based on the TCP-Friendly Multicast)-.18 E
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(Congestion Contr)93.6 120 Q
(ol \(TFMCC\) scheme described in [24] and [5].)-.18 E/F1 10
/Palatino-Bold@0 SF(2.3.)72 144 Q/F2 12/Palatino-Bold@0 SF(Design T)5 E
(radeof)-1.332 E(fs)-.216 E F0(While the various featur)93.6 159.6 Q
(es of NORM ar)-.18 E 2.5(ed)-.18 G(esigned to pr)-2.5 E
(ovide some measur)-.18 E 2.5(eo)-.18 G 2.5(fg)-2.5 G(eneral)-2.5 E
(purpose utility)93.6 171.6 Q 2.5(,i)-1.11 G 2.5(ti)-2.5 G 2.5(si)-2.5 G
(mportant to emphasize the understanding that "no one size fits all" in)
-2.5 E(the r)93.6 183.6 Q(eliable multicast transport ar)-.18 E 2.5
(ena. Ther)-.18 F 2.5(ea)-.18 G .36 -.18(re n)-2.5 H(umer).18 E
(ous engineering tradeof)-.18 E(fs involved in)-.18 E -.18(re)93.6 195.6
S(liable multicast transport design and this r).18 E(equir)-.18 E
(es an incr)-.18 E(eased awar)-.18 E(eness of application)-.18 E
(and network ar)93.6 207.6 Q(chitectur)-.18 E 2.5(ec)-.18 G 2.5
(onsiderations. Performance)-2.5 F -.18(re)2.5 G(quir).18 E(ements af)
-.18 E(fecting design can)-.18 E 2.5(include: gr)93.6 219.6 R
(oup size, heter)-.18 E
(ogeneity \(e.g., capacity and/or delay\), asymmetric delivery)-.18 E
2.5(,d)-1.11 G(ata)-2.5 E(or)93.6 231.6 Q(dering, delivery delay)-.18 E
2.5(,g)-1.11 G -.18(ro)-2.5 G(up dynamics, mobility).18 E 2.5(,c)-1.11 G
(ongestion contr)-2.5 E(ol, and transport acr)-.18 E(oss)-.18 E
(low capacity connections.)93.6 243.6 Q
(NORM contains various parameters to accommodate many of)5 E(these dif)
93.6 255.6 Q(fering r)-.18 E(equir)-.18 E 2.5(ements. The)-.18 F
(NORM pr)2.5 E(otocol and its mechanisms MA)-.18 E 2.5(Yb)-1.11 G 2.5
(ea)-2.5 G(pplied in)-2.5 E
(multicast applications outside of bulk data transfer)93.6 267.6 Q 2.5
(,b)-.74 G(ut ther)-2.5 E 2.5(ei)-.18 G 2.5(sa)-2.5 G 2.5(na)-2.5 G
(ssumed model of bulk)-2.5 E
(transfer transport service that drives the trade-of)93.6 279.6 Q
(fs that determine the scalability and)-.18 E
(performance described in this document.)93.6 291.6 Q
(The ability of NORM to pr)93.6 315.6 Q(ovide r)-.18 E
(eliable data delivery is also governed by any buf)-.18 E(fer)-.18 E
(constraints of the sender and r)93.6 327.6 Q(eceiver applications.)-.18
E(NORM pr)5 E(otocol implementations)-.18 E
(SHOULD be designed to operate with the gr)93.6 339.6 Q(eatest ef)-.18 E
(ficiency and r)-.18 E(obustness possible within)-.18 E
(application-defined buf)93.6 351.6 Q(fer constraints.)-.18 E(Buf)5 E
(fer r)-.18 E(equir)-.18 E(ements for r)-.18 E(eliability)-.18 E 2.5(,a)
-1.11 G 2.5(sa)-2.5 G(lways, ar)-2.5 E 2.5(ea)-.18 G
(function of the delay-bandwidth pr)93.6 363.6 Q
(oduct of the network topology)-.18 E 5(.N)-1.11 G(ORM performs best)-5
E(when allowed mor)93.6 375.6 Q 2.5(eb)-.18 G(uf)-2.5 E(fering r)-.18 E
(esour)-.18 E(ces than typical point-to-point transport pr)-.18 E 2.5
(otocols. This)-.18 F(is because NORM feedback suppr)93.6 387.6 Q
(ession is based upon randomly-delayed transmissions)-.18 E(fr)93.6
399.6 Q(om the r)-.18 E
(eceiver set, rather than immediately transmitted feedback.)-.18 E(Ther)
5 E 2.5(ea)-.18 G .36 -.18(re d)-2.5 H(efinitive).18 E(tradeof)93.6
411.6 Q(fs between buf)-.18 E(fer utilization, gr)-.18 E
(oup size scalability)-.18 E 2.5(,a)-1.11 G(nd ef)-2.5 E
(ficiency of performance.)-.18 E(Lar)93.6 423.6 Q(ge buf)-.18 E
(fer sizes allow the NORM pr)-.18 E(otocol to perform most ef)-.18 E
(ficiently in lar)-.18 E(ge delay-)-.18 E
(bandwidth topologies and allow for longer feedback suppr)93.6 435.6 Q
(ession backof)-.18 E 2.5(ft)-.18 G 2.5(imeouts. This)-2.5 F
(yields impr)93.6 447.6 Q(oved gr)-.18 E(oup size scalability)-.18 E 5
(.N)-1.11 G(ORM can operate with r)-5 E(educed buf)-.18 E
(fering but at a)-.18 E(cost of decr)93.6 459.6 Q(eased ef)-.18 E
(ficiency \(lower r)-.18 E(elative goodput\) and r)-.18 E(educed gr)-.18
E(oup size scalability)-.18 E(.)-1.11 E F1(3.)72 483.6 Q/F3 13
/Palatino-Bold@0 SF(Conformance Statement)5 E F0(This Pr)93.6 499.2 Q(o\
tocol Instantiation document, in conjunction with the RMT Building Bloc\
k)-.18 E(documents of [3] and [4], completely specifies a working r)93.6
511.2 Q(eliable multicast transport)-.18 E(pr)93.6 523.2 Q
(otocol that conforms to the r)-.18 E(equir)-.18 E
(ements described in RFC 2357 [21].)-.18 E(Adamson, et al.)72 768 Q
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(This document specifies the fo\
llowing message types and mechanisms which ar)93.6 120 Q(e)-.18 E
(REQUIRED in complying NORM pr)93.6 132 Q(otocol implementations:)-.18 E
.4 LW 533.8 154.5 72 154.5 DL(Message T)105.915 164 Q 181.555
(ype Purpose)-.9 F 533.8 168.5 72 168.5 DL/F1 10/Courier@0 SF(NORM_DATA)
77 178 Q F0(Sender message for application data transmission.)212 178 Q
(Implementations)5 E(must support at least one of the)212 190 Q F1
(NORM_OBJECT_DATA)2.5 E F0(,)A F1(NORM_OBJECT_FILE)212 202 Q F0 2.5(,o)C
(r)-2.5 E F1(NORM_OBJECT_STREAM)2.5 E F0(delivery services.)2.5 E
(The use of the NORM FEC Object T)212 214 Q
(ransmission Information header)-.9 E(extension is OPTIONAL with)212 226
Q F1(NORM_DATA)2.5 E F0(messages.)2.5 E 533.8 230.5 72 230.5 DL F1
(NORM_CMD\(FLUSH\))77 240 Q F0(Sender command to excite r)212 240 Q
(eceivers for r)-.18 E(epair r)-.18 E(equests in lieu of)-.18 E
(ongoing NORM_DA)212 252 Q 1.48 -.74(TA t)-.74 H 2.5(ransmissions. Note)
.74 F(the use of the)2.5 E
(NORM_CMD\(FLUSH\) for positive acknowledgment of data r)212 264 Q
(eceipt is)-.18 E(OPTIONAL.)212 276 Q 533.8 280.5 72 280.5 DL F1
(NORM_CMD\(SQUELCH\))77 290 Q F0(Sender command to advertise its curr)
212 290 Q(ent valid r)-.18 E(epair window in)-.18 E -.18(re)212 302 S
(sponse to invalid r).18 E(equests for r)-.18 E(epair)-.18 E(.)-.74 E
533.8 306.5 72 306.5 DL F1(NORM_CMD\(REPAIR_ADV\))77 316 Q F0
(Sender command to advertise curr)212 316 Q(ent r)-.18 E
(epair \(and congestion contr)-.18 E(ol)-.18 E(state\) to gr)212 328 Q
(oup when unicast feedback messages ar)-.18 E 2.5(ed)-.18 G 2.5
(etected. Used)-2.5 F(to)2.5 E(contr)212 340 Q(ol/suppr)-.18 E
(ess excessive r)-.18 E(eceiver feedback in asymmetric multicast)-.18 E
(topologies.)212 352 Q 533.8 356.5 72 356.5 DL F1(NORM_CMD\(CC\))77 366
Q F0(Sender command used in collection of r)212 366 Q
(ound trip timing and)-.18 E(congestion contr)212 378 Q(ol status fr)
-.18 E(om gr)-.18 E(oup \(this may be OPTIONAL if)-.18 E
(alternative congestion contr)212 390 Q(ol mechanism and r)-.18 E
(ound trip timing)-.18 E(collection is used\).)212 402 Q 533.8 406.5 72
406.5 DL F1(NORM_NACK)77 416 Q F0(Receiver message used to r)212 416 Q
(equest r)-.18 E(epair of missing transmitted)-.18 E(content.)212 428 Q
533.8 432.5 72 432.5 DL F1(NORM_ACK)77 442 Q F0
(Receiver message used to pr)212 442 Q(oactively pr)-.18 E
(ovide feedback for congestion)-.18 E(contr)212 454 Q(ol purposes.)-.18
E(Also used with the OPTIONAL NORM Positive)5 E(Acknowledgment Pr)212
466 Q(ocess.)-.18 E 533.8 470.5 72 470.5 DL 533.8 154.5 533.8 470.5 DL
72 154.5 72 470.5 DL 204.5 154.5 204.5 470.5 DL(Adamson, et al.)72 768 Q
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(This document also describes t\
he following message types and associated mechanisms)93.6 120 Q
(which ar)93.6 132 Q 2.5(eO)-.18 G(PTIONAL for complying NORM pr)-2.5 E
(otocol implementations:)-.18 E .4 LW 542.3 154.5 72 154.5 DL(Message T)
110.165 164 Q 185.805(ype Purpose)-.9 F 542.3 168.5 72 168.5 DL/F1 10
/Courier@0 SF(NORM_INFO)77 178 Q F0(Sender message for pr)220.5 178 Q
(oviding ancillary context information associated)-.18 E
(with NORM transport objects.)220.5 190 Q
(The use of the NORM FEC Object)5 E -.9(Tr)220.5 202 S
(ansmission Information header extension is OPTIONAL with).9 E F1
(NORM_INFO)220.5 214 Q F0(messages.)2.5 E 542.3 218.5 72 218.5 DL F1
(NORM_CMD\(EOT\))77 228 Q F0(Sender command to indicate it has r)220.5
228 Q(eached end-of-transmission and)-.18 E(will no longer r)220.5 240 Q
(espond to r)-.18 E(epair r)-.18 E(equests.)-.18 E 542.3 244.5 72 244.5
DL F1(NORM_CMD\(ACK_REQ\))77 254 Q F0
(Sender command to support application-defined, positively)220.5 254 Q
(acknowledged commands sent outside of the context of the bulk data)
220.5 266 Q(content being transmitted.)220.5 278 Q
(The NORM Positive Acknowledgment)5 E(Pr)220.5 290 Q(ocedur)-.18 E 2.5
(ea)-.18 G(ssociated with this message type is OPTIONAL.)-2.5 E 542.3
294.5 72 294.5 DL F1(NORM_CMD\(APPLICATION\))77 304 Q F0
(Sender command containing application-defined commands sent)220.5 304 Q
(outside of the context of the bulk data content being transmitted.)
220.5 316 Q 542.3 320.5 72 320.5 DL F1(NORM_REPORT)77 330 Q F0
(Optional message type r)220.5 330 Q
(eserved for experimental implementations of)-.18 E(the NORM pr)220.5
342 Q(otocol.)-.18 E 542.3 346.5 72 346.5 DL 542.3 154.5 542.3 346.5 DL
72 154.5 72 346.5 DL 213 154.5 213 346.5 DL/F2 10/Palatino-Bold@0 SF(4.)
72 372 Q/F3 13/Palatino-Bold@0 SF(Message Formats)5 E F0
(As mentioned in Section 2.1, ther)93.6 387.6 Q 2.5(ea)-.18 G .36 -.18
(re t)-2.5 H(wo primary classes of NORM messages: sender).18 E
(messages and r)93.6 399.6 Q(eceiver messages.)-.18 E F1(NORM_CMD)5 E F0
(,)A F1(NORM_INFO)2.5 E F0 2.5(,a)C(nd)-2.5 E F1(NORM_DATA)2.5 E F0
(message types)2.5 E(ar)93.6 411.6 Q 2.5(eg)-.18 G
(enerated by senders of data content, and)-2.5 E F1(NORM_NACK)2.5 E F0
(and)2.5 E F1(NORM_ACK)2.5 E F0(messages)2.5 E(generated by r)93.6 423.6
Q(eceivers within a)-.18 E/F4 10/Palatino-Italic@0 SF(NormSession)2.5 E
F0 5(.S)C(ender messages SHOULD be governed by)-5 E(congestion contr)
93.6 435.6 Q(ol for Internet use.)-.18 E
(For session management or other purposes, r)5 E(eceivers)-.18 E
(may wish to employ)93.6 447.6 Q F1(NORM_CMD)2.5 E F0
(message transmissions.)2.5 E(The principal rationale for)5 E
(distiguishing sender and r)93.6 459.6 Q(eceiver messages is that r)-.18
E(eceivers will typically need to allocate)-.18 E -.18(re)93.6 471.6 S
(sour).18 E(ces to support r)-.18 E(eliable r)-.18 E(eception fr)-.18 E
(om sender\(s\) and NORM sender messages ar)-.18 E(e)-.18 E
(subject to congestion contr)93.6 483.6 Q 2.5(ol. NORM)-.18 F -.18(re)
2.5 G(ceivers MA).18 E 2.5(Ye)-1.11 G(mploy the)-2.5 E F1(NORM_CMD)2.5 E
F0(message type)2.5 E(for application-defined purposes but it is RECOMM\
ENDED that congestion contr)93.6 495.6 Q(ol and)-.18 E
(feedback implosion issues be addr)93.6 507.6 Q 2.5(essed. Additionally)
-.18 F 2.5(,a)-1.11 G 2.5(na)-2.5 G(uxiliary message type of)-2.5 E
(NORM_REPOR)93.6 519.6 Q 2.5(Ti)-.37 G 2.5(sa)-2.5 G(lso pr)-2.5 E
(ovided for experimental purposes.)-.18 E(This section describes the)5 E
(message formats used by the NORM pr)93.6 531.6 Q 2.5(otocol. These)-.18
F(messages and their fields ar)2.5 E(e)-.18 E -.18(re)93.6 543.6 S(fer)
.18 E(enced in the detailed functional description of the NORM pr)-.18 E
(otocol given in Section 5.)-.18 E(Individual NORM messages ar)93.6
555.6 Q 2.5(ed)-.18 G
(esigned to be compatible with the MTU limitations of)-2.5 E
(encapsulating Internet pr)93.6 567.6 Q
(otocols including IPv4, IPv6, and UDP)-.18 E 5(.T)-1.29 G(he curr)-5 E
(ent NORM)-.18 E(pr)93.6 579.6 Q(otocol specification assumes UDP encap\
sulation and leverages the transport featur)-.18 E(es of)-.18 E(UDP)93.6
591.6 Q 5(.T)-1.29 G(he NORM messages ar)-5 E 2.5(ei)-.18 G
(ndependent of network addr)-2.5 E(esses and can be used in IPv4)-.18 E
(and IPv6 networks.)93.6 603.6 Q F2(4.1.)72 627.6 Q/F5 12
/Palatino-Bold@0 SF(NORM Common Message Header and Extensions)5 E F0
(Ther)93.6 643.2 Q 2.5(ea)-.18 G .36 -.18(re s)-2.5 H
(ome common message fields contained in all NORM message types.).18 E
(Additionally)93.6 655.2 Q 2.5(,ah)-1.11 G(eader extension mechanism is\
 defined to expand the functionality of the)-2.5 E(NORM pr)93.6 667.2 Q
(otocol without r)-.18 E(evision to this document.)-.18 E(All NORM pr)5
E(otocol messages begin)-.18 E
(with a common header with information fields as follows:)93.6 679.2 Q
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q 6(|version| type)93.6 156 R 24(|h)6 G 18(dr_len |)-24 F 72
(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 162(|s)93.6 180 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q/F2 10/Palatino-Italic@0 SF(NORM Common Message Header Format)
213.245 216 Q F0(The "version" field is a 4-bit value indicating the pr)
93.6 240 Q(otocol version number)-.18 E 5(.N)-.74 G(ORM)-5 E
(implementations SHOULD ignor)93.6 252 Q 2.5(er)-.18 G
(eceived messages with version numbers dif)-2.68 E(fer)-.18 E(ent fr)
-.18 E(om)-.18 E(their own. This number is intended to indicate and dis\
tinguish upgrades of the pr)93.6 264 Q(otocol)-.18 E
(which may be non-inter)93.6 276 Q 2.5(operable. The)-.18 F
(NORM version number for this specification is 1.)2.5 E
(The message "type" field is a 4-bit value indicating the NORM pr)93.6
300 Q(otocol message type.)-.18 E(These)5 E(types ar)93.6 312 Q 2.5(ed)
-.18 G(efined as follows:)-2.5 E 26.46(Message V)248.945 342 R(alue)-.92
E F1(NORM_INFO)234.985 366 Q F0(1)37.015 E F1(NORM_DATA)234.985 378 Q F0
(2)37.015 E F1(NORM_CMD)234.985 390 Q F0(3)43.015 E F1(NORM_NACK)234.985
402 Q F0(4)37.015 E F1(NORM_ACK)234.985 414 Q F0(5)43.015 E F1
(NORM_REPORT)234.985 426 Q F0(6)25.015 E
(The 8-bit "hdr_len" field indicates the number of 32-bit wor)93.6 456 Q
(ds that comprise the given)-.18 E(message's header portion.)93.6 468 Q
(This is used to facilitate header extensions that may be applied.)5 E
(The pr)93.6 480 Q(esence of header extensions ar)-.18 E 2.5(ei)-.18 G
(mplied when the "hdr_len" value is gr)-2.5 E(eater than the)-.18 E
(base value for the given message "type".)93.6 492 Q(The "sequence" fie\
ld is a 16-bit value that is set by the message originator as a monoton\
ically)93.6 516 Q(incr)93.6 528 Q(easing number incr)-.18 E
(emented with each NORM message transmitted.)-.18 E(Note that two)5 E
(independent "sequence" spaces MUST be maintained.)93.6 540 Q
(One sequence space SHALL be kept)5 E(for NORM sender messages \()93.6
552 Q F1(NORM_INFO)A F0(,)A F1(NORM_DATA)2.5 E F0 2.5(,a)C(nd)-2.5 E F1
(NORM_CMD)2.5 E F0 2.5(\)g)C(enerated, and a)-2.5 E
(separate, independent "sequence" space SHALL be kept for NORM r)93.6
564 Q(eceiver messages)-.18 E(\()93.6 576 Q F1(NORM_NACK)A F0(and)2.5 E
F1(NORM_NACK)2.5 E F0 2.5(\). The)B
(sender message "sequence" value can be monitor)2.5 E(ed by)-.18 E -.18
(re)93.6 588 S
(ceiving nodes to detect packet losses in the transmissions fr).18 E
(om a sender and used to)-.18 E
(estimate raw packet loss for congestion contr)93.6 600 Q(ol purposes.)
-.18 E(Note that this value is NOT used)5 E(in the NORM pr)93.6 612 Q
(otocol to detect missing r)-.18 E
(eliable data content and does NOT identify the)-.18 E
(application data or FEC payload that may be attached.)93.6 624 Q
(The "sequence" field may also be)5 E(leveraged for pr)93.6 636 Q
(otection fr)-.18 E(om message "r)-.18 E
(eplay" attacks, particularly of)-.18 E F1(NORM_NACK)2.5 E F0(or other)
2.5 E(feedback messages.)93.6 648 Q(For this r)5 E(eason, NORM r)-.18 E
(eceiver messages ar)-.18 E 2.5(ea)-.18 G(lso sequence number)-2.5 E
(ed.)-.18 E(An independent sequence space MUST be used for r)93.6 660 Q
(eceiver messages because when)-.18 E -.18(re)93.6 672 S
(ceivers generate unicast).18 E F1(NORM_NACK)2.5 E F0(or)2.5 E F1
(NORM_ACK)2.5 E F0(messages, those messages will not be)2.5 E
(visible to the gr)93.6 684 Q(oup at lar)-.18 E
(ge that may be performing loss estimation.)-.18 E(Also, NORM)5 E
(congestion contr)93.6 696 Q(ol is applied only to sender messages.)-.18
E(The size of the "sequence" field is)5 E(intended to be suf)93.6 708 Q
(ficient to allow detection of a r)-.18 E
(easonable range of packet loss within the)-.18 E(delay-bandwidth pr)
93.6 720 Q(oduct of expected network connections.)-.18 E
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(The "sour)93.6 120 Q(ce_id" fi\
eld is a 32-bit value identifying the node that sent the message.)-.18 E
(A)5 E(participant's NORM node identifier \()93.6 132 Q/F1 10
/Palatino-Italic@0 SF(NormNodeId)A F0 2.5(\)c)C(an be set accor)-2.5 E
(ding to application needs)-.18 E
(but unique identifiers must be assigned within a single)93.6 144 Q F1
(NormSession)2.5 E F0 5(.I)C 2.5(ns)-5 G(ome cases, use of)-2.5 E
(the host IP addr)93.6 156 Q(ess or a hash of it can suf)-.18 E
(fice, but alternative methodologies for assignment)-.18 E
(and potential collision r)93.6 168 Q
(esolution of node identifiers within a multicast session need to be)
-.18 E(consider)93.6 180 Q 2.5(ed. For)-.18 F(example, the "sour)2.5 E
(ce identifier" mechanism defined in the Real-T)-.18 E(ime)-.55 E(Pr)
93.6 192 Q(otocol \(R)-.18 E(TP\) specification [22] may be applicable \
to use for NORM node identifiers.)-.37 E(At)5 E
(this point in time, the pr)93.6 204 Q
(otocol makes no assumptions about how these unique identifiers ar)-.18
E(e)-.18 E(actually assigned.)93.6 216 Q/F2 10/Palatino-BoldItalic@0 SF
(NORM Header Extensions)93.6 240 Q F0(When header extensions ar)93.6 264
Q 2.5(ea)-.18 G(pplied, they follow the message type's base header and)
-2.5 E(pr)93.6 276 Q(ecede any payload portion.)-.18 E(Ther)5 E 2.5(ea)
-.18 G .36 -.18(re t)-2.5 H
(wo formats for header extensions, both of which).18 E
(begin with an 8-bit "het" \(header extension type\) field.)93.6 288 Q
(One format is pr)5 E(ovided for variable-)-.18 E
(length extensions with "het" values in the range fr)93.6 300 Q
(om 0 thr)-.18 E(ough 127.)-.18 E(The other format is for)5 E
(fixed length \(one 32-bit wor)93.6 312 Q
(d\) extensions with "het" values in the range fr)-.18 E(om 128 thr)-.18
E(ough)-.18 E 2.5(255. These)93.6 324 R(formats ar)2.5 E 2.5(eg)-.18 G
(iven her)-2.5 E(e:)-.18 E/F3 10/Courier@0 SF 114(0123)99.6 348 S 6
(01234567890123456789012345678901)99.6 360 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
372 Q 18(|h)93.6 384 S(et <=127)-18 E 36(|h)18 G 30(el |)-36 F(|)186 E
180(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |)93.6 396 R 120(|H)93.6 408 S
(eader Extension Content)-120 E(|)114 E 180(|.)93.6 420 S 174(.. |)-180
F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
432 Q F1(NORM V)196.435 456 Q(ariable Length Header Extension Format)
-.74 E F3 114(0123)99.6 480 S 6(01234567890123456789012345678901)99.6
492 S(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
93.6 504 Q 18(|h)93.6 516 S(et >=128)-18 E 24(|r)18 G 12(eserved |)-24 F
(Header Extension Content)24 E(|)18 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
528 Q F1(NORM Fixed Length \(32-bit\) Header Extension Format)185.37 540
Q F0(The "Header Extension Content" portion of these header extension f\
ormat is defined for each)93.6 564 Q
(header extension type defined for NORM messages.)93.6 576 Q
(Some header extensions ar)5 E 2.5(ed)-.18 G(efined)-2.5 E
(within this document for NORM baseline FEC and congestion contr)93.6
588 Q(ol operations.)-.18 E/F4 10/Palatino-Bold@0 SF(4.2.)72 612 Q/F5 12
/Palatino-Bold@0 SF(Sender Messages)5 E F0
(NORM sender messages include the)93.6 627.6 Q F3(NORM_DATA)2.5 E F0
(type, the)2.5 E F3(NORM_INFO)2.5 E F0(type, and the)2.5 E F3(NORM_CMD)
93.6 639.6 Q F0(type.)2.5 E F3(NORM_DATA)5 E F0(and)2.5 E F3(NORM_INFO)
2.5 E F0(messages contain application data content)2.5 E(while)93.6
651.6 Q F3(NORM_CMD)2.5 E F0(messages ar)2.5 E 2.5(eu)-.18 G
(sed for various pr)-2.5 E(otocol contr)-.18 E(ol functions.)-.18 E F4
2.5(4.2.1. NORM_DA)72 675.6 R 1.84 -.92(TA M)-.92 H(essage).92 E F0(The)
93.6 691.2 Q F3(NORM_DATA)2.5 E F0(message is expected to be the pr)2.5
E(edominant type transmitted by NORM)-.18 E 2.5(senders. These)93.6
703.2 R(messages ar)2.5 E 2.5(eu)-.18 G
(sed to encapsulate segmented data content for objects of type)-2.5 E F3
(NORM_OBJECT_DATA)93.6 715.2 Q F0(,)A F3(NORM_OBJECT_FILE)2.5 E F0 2.5
(,a)C(nd)-2.5 E F3(NORM_OBJECT_STREAM)2.5 E F0(.)A F3(NORM_DATA)5 E F0
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(messages may contain original or FEC-encoded application data content.)
93.6 120 Q(The format of)93.6 144 Q/F1 10/Courier@0 SF(NORM_DATA)2.5 E
F0(messages is comprised of thr)2.5 E
(ee logical portions: 1\) a fixed-format)-.18 E F1(NORM_DATA)93.6 156 Q
F0(header portion, 2\) a FEC Payload ID portion with a format dependent\
 upon the)2.5 E
(FEC encoding used, and 3\) a payload portion containing sour)93.6 168 Q
(ce or encoded application data)-.18 E 2.5(content. Note)93.6 180 R
(for objects of type)2.5 E F1(NORM_OBJECT_STREAM)2.5 E F0 2.5(,t)C
(he payload portion contains)-2.5 E(additional fields used to appr)93.6
192 Q(opriately r)-.18 E(ecover str)-.18 E(eam content.)-.18 E
(NORM implementations)5 E(MA)93.6 204 Q 2.5(Ya)-1.11 G(lso extend the)
-2.5 E F1(NORM_DATA)2.5 E F0(header to include a FEC Object T)2.5 E
(ransmission Information)-.9 E(\(EXT_FTI\) header extension.)93.6 216 Q
(This allows NORM r)5 E(eceivers to automatically allocate)-.18 E -.18
(re)93.6 228 S(sour).18 E(ces and pr)-.18 E
(operly perform FEC decoding without the need for pr)-.18 E
(e-configuration or)-.18 E(out-of-band information.)93.6 240 Q F1 114
(0123)99.6 264 S 6(01234567890123456789012345678901)99.6 276 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
288 Q(|version| type=2|)93.6 300 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
312 Q 162(|s)93.6 324 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
336 Q 60(|i)93.6 348 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
360 Q 30(|f)93.6 372 S 24(lags |)-30 F 24(fec_id | object_transport_id)
24 F(|)42 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
384 Q 150(|f)93.6 396 S 138(ec_payload_id |)-150 F 180(|.)93.6 408 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
420 Q 96(|h)93.6 432 S(eader_extensions \(if applicable\))-96 E(|)84 E
180(|.)93.6 444 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
456 Q 60(|p)93.6 468 S 48(ayload_len* |)-60 F 30(payload_msg_start* |)42
F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
480 Q 144(|p)93.6 492 S 138(ayload_offset* |)-144 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
504 Q 156(|p)93.6 516 S 138(ayload_data* |)-156 F 180(|.)93.6 528 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
540 Q/F2 10/Palatino-Italic@0 SF(NORM_DA)232.595 564 Q 1.84 -.92(TA M)
-.55 H(essage Format).92 E(*IMPOR)93.6 588 Q -.92(TA)-.55 G(NT NOTE:).92
E(The "payload_len", "payload_msg_start" and "payload_offset" fields ar)
5 E(e)-.18 E(pr)93.6 600 Q(esent only for objects of type)-.18 E F1
(NORM_OBJECT_STREAM)2.5 E F2(.)A(The "payload_len" and "payload_offset"\
 fields allow senders to arbitrarily vary the size of)93.6 624 Q F1
(NORM_DATA)93.6 636 Q F2(payload segments for str)2.5 E 2.5(eams. This)
-.18 F(allows applications to flush transmitted str)2.5 E(eams as)-.18 E
(needed to meet unique str)93.6 648 Q(eaming r)-.18 E(equir)-.18 E 2.5
(ements. For)-.18 F(objects of types)2.5 E F1(NORM_OBJECT_FILE)2.5 E F2
(and)2.5 E F1(NORM_OBJECT_DATA)93.6 660 Q F2 2.5(,t)C(hese fields ar)
-2.5 E 2.5(eu)-.18 G(nnecessary since the r)-2.5 E
(eceiver can calculate the payload)-.18 E
(length and offset information fr)93.6 672 Q
(om the "fec_payload_id" using the block partioning algorithm)-.18 E
(described in the FEC Building Block document [4].)93.6 684 Q
(The "payload_len" field indicates the length \(in)5 E
(bytes\) of the "payload_data" content of the str)93.6 696 Q
(eam data segment.)-.18 E(When "payload_len" is equal to)5 E
(ZERO, this indicates that ther)93.6 708 Q 2.5(ei)-.18 G 2.5(sn)-2.5 G
2.5(o")-2.5 G
(payload_data" content and the "payload_msg_start" field is)-2.5 E
(instead to be interpr)93.6 720 Q(eted as a str)-.18 E(eam contr)-.18 E
(ol code.)-.18 E F0(Adamson, et al.)72 768 Q(Expir)87.875 E
(es: 31 December 2007)-.18 E([Page 15])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Palatino-Italic@0 SF
(The "payload_msg_start" field serves one of two exlusive purposes.)93.6
120 Q(When "payload_len" is a non-)5 E(zer)93.6 132 Q 2.5(ov)-.18 G(alu\
e, the "payload_msg_start" fields is used to mark the location \(within\
 the "payload_data"\))-2.5 E
(field of the start byte of an application-defined message boundary)93.6
144 Q 5(.N)-.37 G(ote that the "payload_msg_start")-5 E
(value is the byte offset of the message boundary plus one.)93.6 156 Q
(Thus, a value of "payload_msg_start" equal)5 E
(to ZERO denotes that no message boundary is pr)93.6 168 Q
(esent, while a "payload_msg_start" value of ONE)-.18 E(indicates the m\
essage boundary is aligned with the beginning of the "payload_data" fie\
ld.)93.6 180 Q(This allows)5 E(NORM r)93.6 192 Q
(eceiver applications to "synchr)-.18 E
(onize" with NORM senders and to be able to pr)-.18 E(operly)-.18 E
(interpr)93.6 204 Q
(et application layer data when joining a NORM session alr)-.18 E
(eady in pr)-.18 E(ogr)-.18 E 2.5(ess. The)-.18 F(NORM)2.5 E
(sender implementation SHOULD pr)93.6 216 Q
(ovide a mechanism for the application to mark such message)-.18 E
(boundaries and set the "payload_msg_start" value accordingly)93.6 228 Q
5(.T)-.37 G(he "payload_msg_start" value will)-5 E(always be less than \
or equal to the "payload_len" value except for the special case of "pay\
load_len =)93.6 240 Q
(0", that indicates the "payload_msg_start" field should be interpr)93.6
252 Q(eted as a "str)-.18 E(eam contr)-.18 E(ol code" \(See)-.18 E
(description below\).)93.6 264 Q(The "payload_len" and "payload_offset"\
 fields allow senders to arbitrarily vary the size of)93.6 288 Q/F2 10
/Courier@0 SF(NORM_DATA)93.6 300 Q F1(payload segments for str)2.5 E 2.5
(eams. This)-.18 F(allows applications to flush transmitted str)2.5 E
(eams as)-.18 E(needed to meet unique str)93.6 312 Q(eaming r)-.18 E
(equir)-.18 E 2.5(ements. For)-.18 F(objects of types)2.5 E F2
(NORM_OBJECT_FILE)2.5 E F1(and)2.5 E F2(NORM_OBJECT_DATA)93.6 324 Q F1
2.5(,t)C(hese fields ar)-2.5 E 2.5(eu)-.18 G(nnecessary since the r)-2.5
E(eceiver can calculate the payload)-.18 E
(length and offset information fr)93.6 336 Q
(om the "fec_payload_id" using the block partioning algorithm)-.18 E
(described in the FEC Building Block document [4].)93.6 348 Q
(When systematic FEC codes \(e.g., "fec_id" =)5 E(129\) ar)93.6 360 Q
2.5(eu)-.18 G(sed, the "payload_len", "payload_msg_start", and "payload\
_offset" fields contain actual)-2.5 E
(payload_data length, start index \(or str)93.6 372 Q(eam contr)-.18 E
(ol code\), and offset values for the associated)-.18 E(application str)
93.6 384 Q
(eam data segment \(the "payload_data" field content\) for those)-.18 E
F2(NORM_DATA)2.5 E F1(messages)2.5 E(containing sour)93.6 396 Q
(ce data symbols.)-.18 E(In)5 E F2(NORM_DATA)2.5 E F1
(messages that contain parity information, these)2.5 E
(fields do not contain values that can be dir)93.6 408 Q(ectly interpr)
-.18 E(eted, but instead ar)-.18 E 2.5(ev)-.18 G(alues computed fr)-2.5
E(om)-.18 E(FEC encoding the "payload_len", "payload_msg_start", and "p\
ayload_offset" fields for the sour)93.6 420 Q(ce)-.18 E
(data segments of the corr)93.6 432 Q(esponding coding block.)-.18 E F0
(The "version", "type", "hdr_len", "sequence", and "sour)93.6 456 Q
(ce_id" fields form the NORM)-.18 E
(Common Message Header as described in Section 4.1.)93.6 468 Q
(The value of the)5 E F2(NORM_DATA)2.5 E F0("type")2.5 E(field is 2.)
93.6 480 Q(The)5 E F2(NORM_DATA)2.5 E F0
(_base_ "hdr_len" value is 4 \(32-bit wor)2.5 E
(ds\) plus the size of the)-.18 E("fec_payload_id" field.)93.6 492 Q
(The "fec_payload_id" field size depends upon the FEC encoding)5 E
(used for the r)93.6 504 Q(efer)-.18 E(enced)-.18 E F1(NormObject)2.5 E
F0 5(.T)C(he "fec_id" field is used to indicate the FEC coding)-5 E 2.5
(type. For)93.6 516 R(example, when small block, systematic codes ar)2.5
E 2.5(eu)-.18 G(sed, a "fec_id" value of 129 is)-2.5 E
(indicated and the size of the "fec_payload_id" is two 32-bit wor)93.6
528 Q 2.5(ds. In)-.18 F(this case the)2.5 E F2(NORM_DATA)93.6 540 Q F0
(base "hdr_len" value is 6.)2.5 E
(The cumulative size of any header extensions applied)5 E
(is added into the "hdr_len" field.)93.6 552 Q(The "instance_id" field \
contains a value generated by the sender to uniquely identify its)93.6
576 Q(curr)93.6 588 Q(ent instance of participation in the)-.18 E F1
(NormSession)2.5 E F0 5(.T)C(his allows r)-5 E(eceivers to detect when)
-.18 E(senders have per)93.6 600 Q(haps left and r)-.18 E
(ejoined a session in pr)-.18 E(ogr)-.18 E 2.5(ess. When)-.18 F 2.5(as)
2.5 G(ender \(identified by)-2.5 E(its "sour)93.6 612 Q
(ce_id"\) is detected to have a new "instance_id", the NORM r)-.18 E
(eceivers SHOULD dr)-.18 E(op)-.18 E(their pr)93.6 624 Q
(evious state on the sender and begin r)-.18 E(eception anew)-.18 E 2.5
(,o)-.92 G 2.5(ra)-2.5 G 2.5(tl)-2.5 G(east tr)-2.5 E
(eat this "instance")-.18 E(as a new)93.6 636 Q 2.5(,s)-.92 G
(eparate sender)-2.5 E(.)-.74 E
(The "grtt" field contains a non-linear quantized r)93.6 660 Q(epr)-.18
E(esentation of the sender)-.18 E('s curr).74 E(ent)-.18 E
(estimate of gr)93.6 672 Q(oup r)-.18 E(ound-trip time \(GR)-.18 E
(TT\) \(this is also r)-.37 E(eferr)-.18 E(ed to as)-.18 E F2(R_max)2.5
E F0(in [24]\).)2.5 E(This)5 E(value is used to contr)93.6 684 Q
(ol timing of the NACK r)-.18 E(epair pr)-.18 E
(ocess and other aspects of pr)-.18 E(otocol)-.18 E
(operation as described in this document.)93.6 696 Q(Normally)5 E 2.5
(,t)-1.11 G(he advertised "grtt" value will)-2.5 E(corr)93.6 708 Q
(espond to what the sender has measur)-.18 E(ed based on feedback fr)
-.18 E(om the gr)-.18 E(oup, but, at low)-.18 E(transmission rates, the\
 advertised "grtt" SHALL be set to MAX\(grttMeasur)93.6 720 Q(ed,)-.18 E
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(NormSegmentSize/senderRate\) wher)93.6 120 Q 2.5(et)-.18 G
(he "NormSegmentSize" is sender)-2.5 E('s segment size in).74 E
(bytes and the "senderRate" is the sender)93.6 132 Q('s curr).74 E
(ent transmission rate in bytes per second.)-.18 E(The)5 E(algorithm fo\
r encoding and decoding this field is described in the RMT NORM Buildin\
g)93.6 144 Q(Block document [3].)93.6 156 Q(The "backof)93.6 171.6 Q
(f" field value is used by r)-.18 E
(eceivers to determine the maximum backof)-.18 E 2.5(ft)-.18 G
(imer value)-2.5 E(used in the timer)93.6 183.6 Q
(-based NORM NACK feedback suppr)-.18 E 2.5(ession. This)-.18 F
(4-bit field supports)2.5 E(values fr)93.6 195.6 Q
(om 0-15 which is multiplied by the sender GR)-.18 E
(TT to determine the maximum)-.37 E(backof)93.6 207.6 Q 2.5(ft)-.18 G
2.5(imeout. The)-2.5 F("backof)2.5 E(f" field informs the r)-.18 E
(eceiver set of the sender)-.18 E('s backof).74 E 2.5(ff)-.18 G(actor)
-2.5 E(parameter ")93.6 219.6 Q/F1 10/Courier@0 SF(Ksender)A F0 2.5
(". Recommended)B(values and their use ar)2.5 E 2.5(ed)-.18 G
(escribed in the NORM)-2.5 E -.18(re)93.6 231.6 S(ceiver NACK pr).18 E
(ocedur)-.18 E 2.5(ed)-.18 G(escription in Section 5.3.)-2.5 E
(The "gsize" field contains a)5 E -.18(re)93.6 243.6 S(pr).18 E
(esentation of the sender)-.18 E('s curr).74 E(ent estimate of gr)-.18 E
(oup size.)-.18 E(This 4-bit field can r)5 E(oughly)-.18 E -.18(re)93.6
255.6 S(pr).18 E(esent values fr)-.18 E(om ten to 500 million wher)-.18
E 2.5(et)-.18 G(he most significant bit value of 0 or 1)-2.5 E -.18(re)
93.6 267.6 S(pr).18 E(esents a mantissa of 1 or 5, r)-.18 E
(espectively and the thr)-.18 E(ee least significant bits incr)-.18 E
(emented)-.18 E(by one r)93.6 279.6 Q(epr)-.18 E
(esent a base 10 exponent \(or)-.18 E(der of magnitude\).)-.18 E
(For examples, a field value of)5 E("0x0" r)93.6 291.6 Q(epr)-.18 E
(esents 1.0e+01 \(10\), a value of "0x8" r)-.18 E(epr)-.18 E
(esents 5.0e+01 \(50\), a value of "0x1")-.18 E -.18(re)93.6 303.6 S(pr)
.18 E(esents 1.0e+02 \(100\), and a value of "0xf" r)-.18 E(epr)-.18 E
(esents 5.0e+08.)-.18 E(For NORM feedback)5 E(suppr)93.6 315.6 Q
(ession purposes, the gr)-.18 E(oup size does not need to be r)-.18 E
(epr)-.18 E(esented with a high degr)-.18 E(ee of)-.18 E(pr)93.6 327.6 Q
2.5(ecision. The)-.18 F(gr)2.5 E
(oup size may even be estimated somewhat conservatively \(i.e.,)-.18 E
(over)93.6 339.6 Q(estimated\) to maintain low levels of feedback traf)
-.18 E 2.5(fic. A)-.18 F(default gr)2.5 E(oup size estimate of)-.18 E
(10,000 \("gsize" = 0x3\) is r)93.6 351.6 Q
(ecommended for general purpose r)-.18 E(eliable multicast applications)
-.18 E(using the NORM pr)93.6 363.6 Q(otocol.)-.18 E
(The "flags" field contains a number of dif)93.6 387.6 Q(fer)-.18 E
(ent binary flags pr)-.18 E(oviding information and hints)-.18 E -.18
(re)93.6 399.6 S(gar).18 E(ding how the r)-.18 E
(eceiver should handle the identified object.)-.18 E
(Defined flags in this field)5 E(include:)93.6 411.6 Q .4 LW 530.63
434.1 72 434.1 DL 62.985(Flag V)127.485 443.6 R 131.04(alue Purpose)-.92
F 530.63 448.1 72 448.1 DL F1(NORM_FLAG_REPAIR)77 457.6 Q F0(0x01)41.435
E(Indicates message is a r)252.03 457.6 Q(epair transmission)-.18 E
530.63 462.1 72 462.1 DL F1(NORM_FLAG_EXPLICIT)77 471.6 Q F0(0x02)29.435
E(Indicates a r)252.03 471.6 Q
(epair segment intended to meet a specific)-.18 E -.18(re)252.03 483.6 S
(ceiver erasur).18 E(e, as compar)-.18 E(ed to parity segments pr)-.18 E
(ovided by)-.18 E(the sender for general purpose \(with r)252.03 495.6 Q
(espect to an FEC)-.18 E(coding block\) erasur)252.03 507.6 Q 2.5(ef)
-.18 G(illing.)-2.5 E 530.63 512.1 72 512.1 DL F1(NORM_FLAG_INFO)77
521.6 Q F0(0x04)53.435 E(Indicates availability of)252.03 521.6 Q F1
(NORM_INFO)2.5 E F0(for object.)2.5 E 530.63 526.1 72 526.1 DL F1
(NORM_FLAG_UNRELIABLE)77 535.6 Q F0(0x08)17.435 E(Indicates that r)
252.03 535.6 Q(epair transmissions for the specified object)-.18 E
(will be unavailable \(One-shot, best ef)252.03 547.6 Q
(fort transmission\).)-.18 E 530.63 552.1 72 552.1 DL F1(NORM_FLAG_FILE)
77 561.6 Q F0(0x10)53.435 E
(Indicates object is "file-based" data \(hint to use disk storage)252.03
561.6 Q(for r)252.03 573.6 Q(eception\).)-.18 E 530.63 578.1 72 578.1 DL
F1(NORM_FLAG_STREAM)77 587.6 Q F0(0x20)41.435 E
(Indicates object is of type NORM_OBJECT_STREAM.)252.03 587.6 Q 530.63
592.1 72 592.1 DL 530.63 434.1 530.63 592.1 DL 72 434.1 72 592.1 DL
244.53 434.1 244.53 592.1 DL 204.5 434.1 204.5 592.1 DL F1
(NORM_FLAG_REPAIR)93.6 617.6 Q F0
(is set when the associated message is a r)2.5 E(epair transmission.)
-.18 E(This)5 E(information can be used by r)93.6 629.6 Q
(eceivers to help observe a join policy wher)-.18 E 2.5(ei)-.18 G 2.5
(ti)-2.5 G 2.5(sd)-2.5 G(esir)-2.5 E(ed that)-.18 E(newly joining r)93.6
641.6 Q(eceivers only begin participating in the NACK pr)-.18 E
(ocess upon r)-.18 E(eceipt of new)-.18 E(\(non-r)93.6 653.6 Q
(epair\) data content.)-.18 E F1(NORM_FLAG_EXPLICIT)5 E F0
(is used to mark r)2.5 E(epair messages sent)-.18 E
(when the data sender has exhausted its ability to pr)93.6 665.6 Q
(ovide "fr)-.18 E(esh" \(pr)-.18 E(eviously untransmitted\))-.18 E
(parity segments as r)93.6 677.6 Q(epair)-.18 E 5(.T)-.74 G
(his flag could possibly be used by intermediate systems)-5 E
(implementing functionality to contr)93.6 689.6 Q(ol sub-casting of r)
-.18 E(epair content to dif)-.18 E(fer)-.18 E(ent legs of a)-.18 E -.18
(re)93.6 701.6 S(liable multicast topology with disparate r).18 E
(epair needs.)-.18 E F1(NORM_FLAG_INFO)5 E F0(is set only when)2.5 E
(optional)93.6 713.6 Q F1(NORM_INFO)2.5 E F0
(content is actually available for the associated object.)2.5 E(Thus, r)
5 E(eceivers)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(will NACK for r)93.6 120 Q
(etransmission of)-.18 E/F1 10/Courier@0 SF(NORM_INFO)2.5 E F0
(only when it is available for a given object.)2.5 E F1
(NORM_FLAG_UNRELIABLE)93.6 132 Q F0
(is set when the sender wishes to transmit an object with only)2.5 E
("best ef)93.6 144 Q(fort" delivery and will not supply r)-.18 E
(epair transmissions for the object.)-.18 E(NORM)5 E -.18(re)93.6 156 S
(ceivers SHOULD NOT execute r).18 E(epair r)-.18 E
(equests for objects marked with the)-.18 E F1(NORM_FLAG_UNRELIABLE)93.6
168 Q F0 2.5(flag. Note)2.5 F(that r)2.5 E(eceivers may inadvertently r)
-.18 E(equest r)-.18 E(epair of)-.18 E(such objects when all segments \
\(or info content\) for those objects ar)93.6 180 Q 2.5(en)-.18 G(ot r)
-2.5 E(eceived \(i.e., a gap)-.18 E
(in the "object_transport_id" sequence is noted\).)93.6 192 Q
(In this case, the sender should invoke the)5 E F1(NORM_CMD\(SQUELCH\))
93.6 204 Q F0(pr)2.5 E(ocess as described in Section 4.2.3.)-.18 E F1
(NORM_FLAG_FILE)5 E F0(can be set)2.5 E(as a "hint" fr)93.6 216 Q
(om the sender that the associated object should be stor)-.18 E
(ed in non-volatile storage.)-.18 E F1(NORM_FLAG_STREAM)93.6 228 Q F0
(is set when the identified object is of type)2.5 E F1
(NORM_OBJECT_STREAM)2.5 E F0(.)A(The pr)93.6 240 Q(esence of)-.18 E F1
(NORM_FLAG_STREAM)2.5 E F0(overrides that of)2.5 E F1(NORM_FLAG_FILE)2.5
E F0(with r)2.5 E(espect to)-.18 E(interpr)93.6 252 Q
(etation of object size and the format of)-.18 E F1(NORM_DATA)2.5 E F0
(messages.)2.5 E(The "fec_id" field corr)93.6 276 Q
(esponds to the FEC Encoding Identifier described in the FEC Building)
-.18 E(Block document [4].)93.6 288 Q(The "fec_id" value implies the fo\
rmat of the "fec_payload_id" field and,)5 E(coupled with FEC Object T)
93.6 300 Q(ransmission Information, the pr)-.9 E(ocedur)-.18 E
(es to decode FEC encoded)-.18 E 2.5(content. Small)93.6 312 R
(block, systematic codes \("fec_id" = 129\) ar)2.5 E 2.5(ee)-.18 G
(xpected to be used for most)-2.5 E(NORM purposes and the)93.6 324 Q F1
(NORM_OBJECT_STREAM)2.5 E F0 -.18(re)2.5 G(quir).18 E
(es systematic FEC codes for most)-.18 E(ef)93.6 336 Q
(ficient performance.)-.18 E
(The "object_transport_id" field is a monotonically and incr)93.6 360 Q
(ementally incr)-.18 E(easing value)-.18 E(assigned by the sender to)
93.6 372 Q/F2 10/Palatino-Italic@0 SF(NormObjects)2.5 E F0
(being transmitted.)2.5 E -.9(Tr)5 G(ansmissions and r).9 E(epair r)-.18
E(equests)-.18 E -.18(re)93.6 384 S
(lated to that object use the same "object_transport_id" value.).18 E
(For sessions of very long or)5 E
(indefinite duration, the "object_transport_id" field may be r)93.6 396
Q(epeated, but it is pr)-.18 E(esumed that)-.18 E
(the 16-bit field size pr)93.6 408 Q
(ovides an adequate enough sequence space to avoid object confusion)-.18
E(amongst r)93.6 420 Q(eceivers and sour)-.18 E(ces \(i.e., r)-.18 E
(eceivers SHOULD r)-.18 E(e-synchr)-.18 E(onize with a server when)-.18
E -.18(re)93.6 432 S(ceiving object sequence identifiers suf).18 E
(ficiently out-of-range with the curr)-.18 E(ent state kept for)-.18 E
2.5(ag)93.6 444 S(iven sour)-2.5 E 2.5(ce\). During)-.18 F
(the course of its transmission within a NORM session, an object is)2.5
E(uniquely identified by the concatenation of the sender "sour)93.6 456
Q(ce_id" and the given)-.18 E 2.5("object_transport_id". Note)93.6 468 R
(that)2.5 E F1(NORM_INFO)2.5 E F0
(messages associated with the identified object)2.5 E
(carry the same "object_transport_id" value.)93.6 480 Q
(The "fec_payload_id" identifies the attached)93.6 504 Q F1(NORM_DATA)
2.5 E F0("payload" content.)2.5 E(The size and)5 E(format of the "fec_p\
ayload_id" field depends upon the FEC type indicated by the "fec_id")
93.6 516 Q 2.5(field. These)93.6 528 R(formats ar)2.5 E 2.5(eg)-.18 G
(iven in the descriptions of specific FEC schemes as described in the)
-2.5 E(IETF FEC Basic Schemes document [25]. or additional FEC Scheme d\
ocuments that may be)93.6 540 Q 2.5(defined. As)93.6 552 R
(an example, the format of the "fec_payload_id" format for Small Block,)
2.5 E(Systematic codes \("fec_id" = 129\) is given her)93.6 564 Q(e:)
-.18 E F1 114(0123)99.6 588 S 6(01234567890123456789012345678901)99.6
600 S(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
93.6 612 Q 138(|s)93.6 624 S 120(ource_block_number |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
636 Q 48(|s)93.6 648 S 36(ource_block_len |)-48 F 36
(encoding_symbol_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
660 Q F2(Example FEC Payload ID Field \("fec_payload_id"\) Format)
180.105 684 Q(for Small Block, Systematic Codes \("fec_id" = 129\))
196.055 696 Q F0(In this example FEC payload identifier)93.6 720 Q 2.5
(,t)-.74 G(he "sour)-2.5 E(ce_block_number", "sour)-.18 E
(ce_block_len", and)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
("encoding_symbol_id" fields corr)93.6 120 Q(espond to the "Sour)-.18 E
(ce Block Number", "Sour)-.18 E(ce Block)-.18 E(Length, and "Encoding S\
ymbol ID" fields of the FEC Payload ID format given by the FEC)93.6 132
Q(Basic Schemes document [25]. for the Small Block Systematic FEC Schem\
e identified by a)93.6 144 Q("fec_id" value of 129.)93.6 156 Q
(The "sour)5 E(ce_block_number" identifies the coding block's r)-.18 E
(elative)-.18 E(position with a)93.6 168 Q/F1 10/Palatino-Italic@0 SF
(NormObject)2.5 E F0 5(.N)C(ote that, for)-5 E F1(NormObjects)2.5 E F0
(of type)2.5 E/F2 10/Courier@0 SF(NORM_OBJECT_STREAM)2.5 E F0 2.5(,t)C
(he)-2.5 E("sour)93.6 180 Q
(ce_block_number" may wrap for very long lived sessions.)-.18 E
(The "sour)5 E(ce_block_len")-.18 E(indicates the number of user data s\
egments in the identified coding block.)93.6 192 Q(Given the)5 E("sour)
93.6 204 Q
(ce_block_len" information of how many symbols of application data ar)
-.18 E 2.5(ec)-.18 G(ontained in)-2.5 E(the block, the r)93.6 216 Q(ece\
iver can determine whether the attached segment is data or parity conte\
nt)-.18 E(and tr)93.6 228 Q(eat it appr)-.18 E(opriately)-.18 E 5(.S)
-1.11 G(ome applications may dynamically "shorten" code blocks when)-5 E
(the pending information content is not pr)93.6 240 Q
(edictable \(e.g. r)-.18 E(eal-time message str)-.18 E 2.5(eams\). In)
-.18 F(that)2.5 E(case, the "sour)93.6 252 Q(ce_block_len" value given \
for an "encoding_symbol_id" that contains FEC)-.18 E
(parity content SHALL take pr)93.6 264 Q(ecedence over the "sour)-.18 E
(ce_block_len" value pr)-.18 E(ovided for any)-.18 E
(packets containing sour)93.6 276 Q(ce symbols. Also, the "sour)-.18 E
(ce_block_len" value given for an or)-.18 E(dinally)-.18 E
(higher "encoding_symbol_id" SHALL take pr)93.6 288 Q
(ecedence over the "sour)-.18 E(ce_block_len" given for)-.18 E
(prior encoding symbols.)93.6 300 Q(The r)5 E
(eason for this is that the sender may only know the maximum)-.18 E
(sour)93.6 312 Q(ce block length at the time is transmitting sour)-.18 E
(ce symbols, but then subsequently)-.18 E
("shorten" the code and then pr)93.6 324 Q(ovide that last sour)-.18 E
(ce symbol and/or encoding symbols with)-.18 E(FEC parity content.)93.6
336 Q
(The "encoding_symbol_id" identifies which specific symbol \(segment\))5
E(within the coding block the attached payload conveys.)93.6 348 Q
(Depending upon the value of the)5 E
("encoding_symbol_id" and the associated "sour)93.6 360 Q
(ce_block_len" parameters for the block, the)-.18 E
(symbol \(segment\) r)93.6 372 Q(efer)-.18 E
(enced may be a user data or an FEC parity segment.)-.18 E
(For systematic)5 E(codes, encoding symbols number)93.6 384 Q
(ed less than the)-.18 E F2(source_block_len)2.5 E F0(contain original)
2.5 E(application data while segments gr)93.6 396 Q
(eater than or equal to)-.18 E F2(source_block_len)2.5 E F0(contain)2.5
E(parity symbols calculated for the block.)93.6 408 Q
(The concatenation of)5 E F2(object_transport_id::fec_payload_id)93.6
420 Q F0(can be viewed as a unique transport)2.5 E(pr)93.6 432 Q
(otocol data unit identifier for the attached segment with r)-.18 E
(espect to the NORM sender)-.18 E('s).74 E(instance within a session.)
93.6 444 Q(Additional FEC Object T)93.6 468 Q
(ransmission Information \(as described in the FEC Building Block)-.9 E
(document [4]\) is r)93.6 480 Q(equir)-.18 E(ed to pr)-.18 E(operly r)
-.18 E(eceive and decode NORM transport objects.)-.18 E(This)5 E
(information MA)93.6 492 Q 2.5(Yb)-1.11 G 2.5(ep)-2.5 G -.18(ro)-2.5 G
(vided as out-of-band session information.).18 E(However)5 E 2.5(,i)-.74
G 2.5(ns)-2.5 G(ome cases,)-2.5 E(it may be useful for the sender to in\
clude this information "in-band" to facilitate r)93.6 504 Q(eceiver)-.18
E(operation with minimal pr)93.6 516 Q 2.5(econfiguration. For)-.18 F
(this purpose, the NORM FEC Object)2.5 E -.9(Tr)93.6 528 S
(ansmission Information Header Extension \(EXT_FTI\) is defined.).9 E
(This header extension)5 E(MA)93.6 540 Q 2.5(Yb)-1.11 G 2.5(ea)-2.5 G
(pplied to)-2.5 E F2(NORM_DATA)2.5 E F0(and)2.5 E F2(NORM_INFO)2.5 E F0
(messages to pr)2.5 E(ovide this necessary)-.18 E 2.5(information. The)
93.6 552 R(format of the EXT_FTI consists of two parts, a general part \
that contains)2.5 E(the size of the associated transport object and a p\
ortion that depends upon the FEC scheme)93.6 564 Q(being used.)93.6 576
Q(The "fec_id" field in)5 E F2(NORM_DATA)2.5 E F0(and)2.5 E F2
(NORM_INFO)2.5 E F0(messages identifies the FEC)2.5 E 2.5(scheme. The)
93.6 588 R(format of the EXT_FTI)2.5 E(general part is given her)5 E(e.)
-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q 24(|h)93.6 156 S(et = 64)-24 E 24(|h)18 G(el = 4)-24 E 42(|o)24 G
(bject_size \(msb\))-42 E(|)42 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 138(|o)93.6 180 S(bject_size \(lsb\))-138 E(|)138 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 108(|F)93.6 204 S(EC Scheme specific content ...)-108 E(|)84 E/F2
10/Palatino-Italic@0 SF(FEC Object T)160 228 Q
(ransmission Information Header Extension \(EXT_FTI\))-1.11 E F0(The he\
ader extension type "het" field value for the EXT_FTI header extension \
is 64.)93.6 252 Q(The)5 E(header extension length "hel" value depends u\
pon the format of the FTI for FEC code type)93.6 264 Q
(identified by the "fec_id" field.)93.6 276 Q(The 48-bit "object_size" \
field indicates the total length of the object \(in bytes\) for the sta\
tic)93.6 300 Q(object types of)93.6 312 Q F1(NORM_OBJECT_FILE)2.5 E F0
(and)2.5 E F1(NORM_OBJECT_DATA)2.5 E F0 5(.T)C
(his information is used by)-5 E -.18(re)93.6 324 S
(ceivers to determine storage r).18 E(equir)-.18 E
(ements and/or allocate storage for the r)-.18 E(eceived object.)-.18 E
(Receivers with insuf)93.6 336 Q
(ficient storage capability may wish to for)-.18 E(ego r)-.18 E
(eliable r)-.18 E(eception \(i.e., not)-.18 E
(NACK for\) of the indicated object.)93.6 348 Q
(In the case of objects of type)5 E F1(NORM_OBJECT_STREAM)2.5 E F0 2.5
(,t)C(he)-2.5 E("object_size" field is used by the sender to advertise \
the size of its str)93.6 360 Q(eam buf)-.18 E(fer to the)-.18 E -.18(re)
93.6 372 S(ceiver gr).18 E 2.5(oup. In)-.18 F(turn, the r)2.5 E
(eceivers SHOULD use this information to allocate a str)-.18 E(eam)-.18
E(buf)93.6 384 Q(fer for r)-.18 E(eception of corr)-.18 E
(esponding size.)-.18 E(As noted, the format of the extension depends u\
pon the FEC code in use, but in general it)93.6 408 Q
(SHOULD contain any r)93.6 420 Q(equir)-.18 E
(ed details on the FEC code in use \(e.g., FEC Instance ID, etc.\).)-.18
E(As an example, the format of the EXT_FTI for small block systematic c\
odes \("fec_id" = 129\) is)93.6 432 Q(given her)93.6 444 Q(e:)-.18 E F1
114(0123)99.6 468 S 6(01234567890123456789012345678901)99.6 480 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
492 Q 24(|h)93.6 504 S(et = 64)-24 E 24(|h)18 G(el = 4)-24 E 42(|o)24 G
(bject_size \(msb\))-42 E(|)42 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
516 Q 138(|o)93.6 528 S(bject_size \(lsb\))-138 E(|)138 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
540 Q 42(|f)93.6 552 S 48(ec_instance_id |)-42 F 48(segment_size |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
564 Q 42(|f)93.6 576 S 36(ec_max_block_len |)-42 F 42(fec_num_parity |)
54 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
93.6 588 Q F2(Example FEC Object T)165.55 612 Q
(ransmission Information Header Extension)-1.11 E
(\(EXT_FTI\) for Small Block, Systematic Codes \("fec_id" = 129\))
171.755 624 Q F0
(In this example \(for "fec_id" = 129\), the "hel" field value is 4.)
93.6 648 Q(The size of the EXT_FTI header)5 E(extension may be dif)93.6
660 Q(fer)-.18 E(ent for other FEC schemes.)-.18 E
(The 48-bit "object_size" serves the purpose described pr)93.6 684 Q
(eviously)-.18 E(.)-1.11 E(The "fec_instance_id" corr)93.6 708 Q
(esponds to the "FEC Instance ID" described in the FEC Building)-.18 E
(Block document [4].)93.6 720 Q
(In this case, the "fec_instance_id" is a value corr)5 E
(esponding to the)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(particular type of Small Block\
 Systematic Code being used \(e.g., Reed-Solomon GF\(2^8\),)93.6 120 Q
(Reed-Solomon GF\(2^16\), etc\).)93.6 132 Q(The standar)5 E
(dized assignment of FEC Instance ID values is)-.18 E(described in [4].)
93.6 144 Q(The "segment_size" field indicates the sender)5 E('s curr).74
E(ent setting for)-.18 E(maximum message payload content \(in bytes\).)
93.6 156 Q(This allows r)5 E(eceivers to allocate appr)-.18 E(opriate)
-.18 E(buf)93.6 168 Q(fering r)-.18 E(esour)-.18 E
(ces and to determine other information in or)-.18 E(der to pr)-.18 E
(operly pr)-.18 E(ocess r)-.18 E(eceived)-.18 E(data messaging.)93.6 180
Q -.9(Ty)5 G(pically).9 E 2.5(,F)-1.11 G
(EC parity symbol segments will be of this size.)-2.5 E
(The "fec_max_block_len" indicates the curr)93.6 204 Q
(ent maximum number of user data segments per)-.18 E
(FEC coding block to be used by the sender during the session.)93.6 216
Q(This allows r)5 E(eceivers to)-.18 E(allocate appr)93.6 228 Q
(opriate buf)-.18 E(fer space for buf)-.18 E
(fering blocks transmitted by the sender)-.18 E(.)-.74 E
(The "fec_num_parity" corr)93.6 252 Q
(esponds to the "maximum number of encoding symbols that can)-.18 E
(be generated for any sour)93.6 264 Q
(ce block" as described in for FEC Object T)-.18 E
(ransmission Information)-.9 E(for Small Block Systematic Codes in the \
FEC Building Block document [4].)93.6 276 Q(For example,)5 E
(Reed-Solomon codes may be arbitrarily shortened to cr)93.6 288 Q
(eate dif)-.18 E(fer)-.18 E(ent code variations for a)-.18 E
(given block length.)93.6 300 Q(In the case of Reed-Solomon \(GF\(2^8\)\
 and GF\(2^16\)\) codes, this value)5 E
(indicates the maximum number of parity segments available fr)93.6 312 Q
(om the sender for the coding)-.18 E 2.5(blocks. This)93.6 324 R
(field MA)2.5 E 2.5(Yb)-1.11 G 2.5(ei)-2.5 G(nterpr)-2.5 E(eted dif)-.18
E(fer)-.18 E(ently for other systematic codes as they ar)-.18 E(e)-.18 E
(defined.)93.6 336 Q(The payload portion of)93.6 360 Q/F1 10/Courier@0
SF(NORM_DATA)2.5 E F0(messages includes sour)2.5 E
(ce data or FEC encoded)-.18 E(application content.)93.6 372 Q
(Again, the content of this payload depends upon the FEC scheme being)5
E 2.5(employed. Additionally)93.6 384 R 2.5(,s)-1.11 G(upport for str)
-2.5 E(eaming using the)-.18 E F1(NORM_OBJECT_STREAM)2.5 E F0(type,)2.5
E(necessitates some additional content in the payload.)93.6 396 Q
(The "payload_len", "payload_msg_start", and "payload_of)93.6 420 Q
(fset" fields ar)-.18 E 2.5(ep)-.18 G -.18(re)-2.5 G(sent ONL).18 E 2.5
(Yf)-.92 G(or)-2.5 E(transport objects of type)93.6 432 Q F1
(NORM_OBJECT_STREAM)2.5 E F0 5(.F)C(or senders employing systematic FEC)
-5 E(encoding, these fields contain values that can be interpr)93.6 444
Q(eted dir)-.18 E(ectly for)-.18 E F1(NORM_DATA)2.5 E F0
(messages containing original application sour)93.6 456 Q
(ce data content.)-.18 E(But, for)5 E F1(NORM_DATA)2.5 E F0(messages)2.5
E(containing calculated parity content, these fields will contain value\
s computed by FEC)93.6 468 Q
(encoding of the "payload_msg_start", "payload_len" and "payload_of)93.6
480 Q(fset" values of the)-.18 E F1(NORM_DATA)93.6 492 Q F0
(data segments for the corr)2.5 E
(esponding FEC coding block and cannot be)-.18 E(interpr)93.6 504 Q
(eted dir)-.18 E(ectly)-.18 E 5(.T)-1.11 G
(he actual "payload_msg_start", "payload_len" and "payload_of)-5 E
(fset")-.18 E(values of missing data content can be determined upon dec\
oding a FEC coding block.)93.6 516 Q(Note)5 E
(that these fields do NOT contribute to the value of the)93.6 528 Q F1
(NORM_DATA)2.5 E F0("hdr_len" field.)2.5 E(These)5 E(fields ar)93.6 540
Q 2.5(ep)-.18 G -.18(re)-2.5 G
(sent only when the "flags" portion of the).18 E F1(NORM_DATA)2.5 E F0
(message indicate the)2.5 E(transport object is of type)93.6 552 Q F1
(NORM_OBJECT_STREAM)2.5 E F0(.)A(The "payload_len" value, when non-zer)
93.6 576 Q(o, indicates the size, in bytes, of the sour)-.18 E
(ce content)-.18 E(contained in the "payload_data" field.)93.6 588 Q
(If the "payload_len" value is equal to ZERO, this)5 E(indicates that t\
he "payload_msg_start" field should be alternatively interpr)93.6 600 Q
(eted as a str)-.18 E(eam)-.18 E(contr)93.6 612 Q(ol code.)-.18 E
(The only str)5 E(eam contr)-.18 E(ol code curr)-.18 E(ently defined is)
-.18 E F1(NORM_STREAM_END = 0)2.5 E F0(.)A
(This code indicates that the sender is terminating transmission of str)
93.6 624 Q(eam content at the)-.18 E(corr)93.6 636 Q
(esponding position in the str)-.18 E(eam and the r)-.18 E
(eceiver should not expect content \(or NACK)-.18 E
(for any content\) following that position in the str)93.6 648 Q 2.5
(eam. Futur)-.18 F 2.5(ev)-.18 G(ersions of this specification)-2.5 E
(may define additional str)93.6 660 Q(eam contr)-.18 E
(ol codes if necessary)-.18 E(.)-1.11 E
(When the "payload_len" value is non-zer)93.6 684 Q
(o, the "payload_msg_start" field, when it is set to a)-.18 E(non-zer)
93.6 696 Q 2.5(ov)-.18 G(alue, indicates that the associated "payload_d\
ata" content contains an application-)-2.5 E
(defined message boundary \(start-of-message\).)93.6 708 Q
(When such a message boundary is indicated,)5 E
(the first byte of an application-defined message, with r)93.6 720 Q
(espect to the "payload_data" field,)-.18 E(Adamson, et al.)72 768 Q
(Expir)87.875 E(es: 31 December 2007)-.18 E([Page 21])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(will be found at an of)93.6 120
Q(fset of "payload_msg_start - 1" bytes.)-.18 E(Thus, if a)5 E/F1 10
/Courier@0 SF -3.5(NORM_OBJECT_STREAM NORM_DATA)93.6 132 R F0
(payload contains the start of an application message at)2.5 E(the firs\
t byte of the "payload_data" field, the value of the "payload_msg_start\
" field will be)93.6 144 Q 2.5('1'. Again,)93.6 156 R(if the value of t\
he "payload_msg_start" field is ZERO, no message boundary is)2.5 E 2.5
(indicated. It)93.6 168 R(is RECOMMENDED that NORM implementations pr)
2.5 E(ovide sender str)-.18 E(eam)-.18 E(applications with a capability\
 to mark message boundaries in this manner)93.6 180 Q 5(.S)-.74 G
(imilarly)-5 E 2.5(,t)-1.11 G(he)-2.5 E(NORM r)93.6 192 Q
(eceiver SHOULD enable the application to r)-.18 E
(ecover such message boundary)-.18 E 2.5(information. This)93.6 204 R
(enables NORM r)2.5 E(eceivers to "synchr)-.18 E
(onize" with transmitted message)-.18 E(str)93.6 216 Q(eam content in a\
 meaningful way \(i.e., meaningful to the application\) at any time, wh\
ether)-.18 E(joining the session late, or departing the session and r)
93.6 228 Q(eturning.)-.18 E(and "payload_of)93.6 252 Q
(fset" fields indicate the size and r)-.18 E
(elative position \(within the str)-.18 E(eam\) of the)-.18 E(sour)93.6
264 Q(ce content contained in the "payload_data" field.)-.18 E
(Note that for long-lived str)5 E(eams, the)-.18 E("payload_of)93.6 276
Q(fset" field may wrap.)-.18 E
(The "payload_data" field contains the original application sour)93.6
300 Q(ce or parity content for the)-.18 E
(symbol identified by the "fec_payload_id".)93.6 312 Q
(The length of this field SHALL be limited to a)5 E
(maximum of the sender)93.6 324 Q('s).74 E/F2 10/Palatino-Italic@0 SF
(NormSegmentSize)2.5 E F0(bytes as given in the FTI for the object.)2.5
E(Note the)5 E(length of this field for messages containing parity cont\
ent will always be of length)93.6 336 Q F2(NormSegmentSize)93.6 348 Q F0
5(.W)C
(hen encoding data segments of varying sizes, the FEC encoder SHALL)-5 E
(assume ZERO value padding for data segments with length less than the)
93.6 360 Q F2(NormSegmentSize)2.5 E F0(.)A
(It is RECOMMENDED that a sender)93.6 372 Q('s).74 E F2(NormSegmentSize)
2.5 E F0(generally be constant for the)2.5 E(duration of a given sender)
93.6 384 Q
('s term of participation in the session, but may possibly vary on a).74
E(per)93.6 396 Q(-object basis.)-.18 E(The)5 E F2(NormSegmentSize)2.5 E
F0(is expected to be configurable by the sender)2.5 E(application prior\
 to session participation as needed for network topology maximum)93.6
408 Q(transmission unit \(MTU\) considerations.)93.6 420 Q
(For IPv6, MTU discovery may be possibly)5 E
(leveraged at session startup to perform this configuration.)93.6 432 Q
(The "payload_data" content may)5 E(be deliver)93.6 444 Q(ed dir)-.18 E
(ectly to the application for sour)-.18 E
(ce symbols \(when systematic FEC encoding)-.18 E
(is used\) or upon decoding of the FEC block.)93.6 456 Q(For)5 E F1
(NORM_OBJECT_FILE)2.5 E F0(and)2.5 E F1(NORM_OBJECT_STREAM)93.6 468 Q F0
(objects, the data segment length and of)2.5 E
(fset can be calculated using)-.18 E(the block paritioning algorithm de\
scribed in the FEC Building Block document [4].)93.6 480 Q(For)5 E F1
(NORM_OBJECT_STREAM)93.6 492 Q F0(objects, the length and of)2.5 E
(fset is obtained fr)-.18 E(om the segment's)-.18 E(corr)93.6 504 Q
(esponding "payload_len" and "payload_of)-.18 E(fset" fields.)-.18 E/F3
10/Palatino-Bold@0 SF 2.5(4.2.2. NORM_INFO)72 528 R(Message)2.5 E F0
(The)93.6 543.6 Q F1(NORM_INFO)2.5 E F0
(message is used to convey OPTIONAL, application-defined, "out-of-band")
2.5 E(context information for transmitted)93.6 555.6 Q F2(NormObjects)
2.5 E F0 5(.A)C 2.5(ne)-5 G(xample)-2.5 E F1(NORM_INFO)2.5 E F0
(use for bulk file)2.5 E(transfer is to place MIME type information for\
 the associated file, data, or str)93.6 567.6 Q(eam object into)-.18 E
(the)93.6 579.6 Q F1(NORM_INFO)2.5 E F0 2.5(payload. Receivers)2.5 F
(may use the)2.5 E F1(NORM_INFO)2.5 E F0(content to make a decision as)
2.5 E(whether to participate in r)93.6 591.6 Q(eliable r)-.18 E
(eception of the associated object.)-.18 E(Each)5 E F2(NormObject)2.5 E
F0(can)2.5 E(have an independent unit of)93.6 603.6 Q F1(NORM_INFO)2.5 E
F0(associated with it.)2.5 E F1(NORM_DATA)5 E F0(messages contain a)2.5
E(flag to indicate the availability of)93.6 615.6 Q F1(NORM_INFO)2.5 E
F0(for a given)2.5 E F2(NormObject)2.5 E F0 5(.N)C(ORM r)-5 E
(eceivers may)-.18 E(NACK for r)93.6 627.6 Q(etransmission of)-.18 E F1
(NORM_INFO)2.5 E F0(when they have not r)2.5 E(eceived it for a given)
-.18 E F2(NormObject)93.6 639.6 Q F0 5(.T)C(he size of the)-5 E F1
(NORM_INFO)2.5 E F0(content is limited to that of a single)2.5 E F2
(NormSegmentSize)93.6 651.6 Q F0(for the given sender)2.5 E 5(.T)-.74 G
(his atomic natur)-5 E 2.5(ea)-.18 G(llows the)-2.5 E F1(NORM_INFO)2.5 E
F0(to be)2.5 E(rapidly and ef)93.6 663.6 Q(ficiently r)-.18 E(epair)-.18
E(ed within the NORM r)-.18 E(eliable transmission pr)-.18 E(ocess.)-.18
E(When)93.6 687.6 Q F1(NORM_INFO)2.5 E F0(content is available for a)2.5
E F2(NormObject)2.5 E F0 2.5(,t)C(he NORM_FLAG_INFO flag)-2.5 E
(SHALL be set in)93.6 699.6 Q F1(NORM_DATA)2.5 E F0
(messages for the corr)2.5 E(esponding "object_transport_id" and the)
-.18 E F1(NORM_INFO)93.6 711.6 Q F0
(message shall be transmitted as the first message for the)2.5 E F2
(NormObject)2.5 E F0(.)A(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q(|version| type=1|)93.6 156 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 162(|s)93.6 180 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 60(|i)93.6 204 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 30(|f)93.6 228 S 24(lags | fec_id)-30 F 30(|o)24 G 36
(bject_transport_id |)-30 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
240 Q 96(|h)93.6 252 S(eader_extensions \(if applicable\))-96 E(|)84 E
180(|.)93.6 264 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
276 Q 150(|p)93.6 288 S 150(ayload_data |)-150 F 180(|.)93.6 300 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
312 Q/F2 10/Palatino-Italic@0 SF(NORM_INFO Message Format)233.8 336 Q F0
(The "version", "type", "hdr_len", "sequence", and "sour)93.6 360 Q
(ce_id" fields form the NORM)-.18 E
(Common Message Header as described in Section 4.1.)93.6 372 Q
(The value of "hdr_len" field when no)5 E(header extensions ar)93.6 384
Q 2.5(ep)-.18 G -.18(re)-2.5 G(sent is 4.).18 E
(The "instance_id", "grtt", "backof)93.6 408 Q
(f", "gsize", "flags", "fec_id", and "object_transport_id" fields)-.18 E
(carry the same information and serve the same purpose as with)93.6 420
Q F1(NORM_DATA)2.5 E F0(messages.)2.5 E(These values allow the r)93.6
432 Q(eceiver to pr)-.18 E(epar)-.18 E 2.5(ea)-.18 G(ppr)-2.5 E
(opriate buf)-.18 E(fering, etc, for further)-.18 E(transmissions fr)
93.6 444 Q(om the sender when)-.18 E F1(NORM_INFO)2.5 E F0
(is the first message r)2.5 E(eceived.)-.18 E(As with)93.6 468 Q F1
(NORM_DATA)2.5 E F0
(messages, the NORM FTI Header Extension \(EXT_FTI\) may be)2.5 E
(optionally applied to)93.6 480 Q F1(NORM_INFO)2.5 E F0 2.5(messages. T)
2.5 F 2.5(oc)-.92 G(onserve pr)-2.5 E(otocol over)-.18 E
(head, some NORM)-.18 E
(implementations may wish to apply the EXT_FTI when used to)93.6 492 Q
F1(NORM_INFO)2.5 E F0(messages only)2.5 E(and not to)93.6 504 Q F1
(NORM_DATA)2.5 E F0(messages.)2.5 E(The)93.6 528 Q F1(NORM_INFO)2.5 E F0
("payload_data" field contains sender application-defined content which\
 can)2.5 E(be used by r)93.6 540 Q
(eceiver applications for various purposes as described above.)-.18 E/F3
10/Palatino-Bold@0 SF 2.5(4.2.3. NORM_CMD)72 564 R(Messages)2.5 E F1
(NORM_CMD)93.6 579.6 Q F0(messages ar)2.5 E 2.5(et)-.18 G
(ransmitted by senders to perform a number of dif)-2.5 E(fer)-.18 E
(ent pr)-.18 E(otocol)-.18 E 2.5(functions. This)93.6 591.6 R
(includes functions such as r)2.5 E
(ound-trip timing collection, congestion contr)-.18 E(ol)-.18 E
(functions, synchr)93.6 603.6 Q(onization of sender/r)-.18 E(eceiver r)
-.18 E(epair "windows", and notification of sender)-.18 E 2.5(status. A)
93.6 615.6 R(cor)2.5 E 2.5(es)-.18 G(et of)-2.5 E F1(NORM_CMD)2.5 E F0
(messages is enumerated.)2.5 E(Additionally)5 E 2.5(,ar)-1.11 G
(ange of command)-2.5 E(types r)93.6 627.6 Q
(emain available for potential application-specific use.)-.18 E(Some)5 E
F1(NORM_CMD)2.5 E F0(types may)2.5 E(have dynamic content attached.)93.6
639.6 Q(Any attached content will be limited to maximum length of)5 E
(the sender)93.6 651.6 Q F2(NormSegmentSize)2.5 E F0(to r)2.5 E
(etain the atomic natur)-.18 E 2.5(eo)-.18 G 2.5(fc)-2.5 G 2.5
(ommands. All)-2.5 F F1(NORM_CMD)2.5 E F0(messages begin with a common \
set of fields, after the usual NORM message common)93.6 663.6 Q(header)
93.6 675.6 Q 5(.T)-.74 G(he standar)-5 E(d)-.18 E F1(NORM_CMD)2.5 E F0
(fields ar)2.5 E(e:)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
(es: 31 December 2007)-.18 E([Page 23])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q(|version| type=3|)93.6 156 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 162(|s)93.6 180 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 60(|i)93.6 204 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 30(|f)93.6 228 S 18(lavor |)-30 F(|)282 E 42
(+-+-+-+-+-+-+-+-+ NORM_CMD)93.6 240 R 132(Content +)6 F 180(|.)93.6 252
S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
264 Q/F2 10/Palatino-Italic@0 SF(NORM_CMD Standard Fields)235.46 288 Q
F0(The "version", "type", "hdr_len", "sequence", and "sour)93.6 312 Q
(ce_id" fields form the NORM)-.18 E
(Common Message Header as described in Section 4.1.)93.6 324 Q
(The value of the "hdr_len" field for)5 E F1(NORM_CMD)93.6 336 Q F0
(messages without header extensions pr)2.5 E
(esent depends upon the "flavor" field.)-.18 E
(The "instance_id", "grtt", "backof)93.6 360 Q
(f", and "gsize" fields pr)-.18 E(ovide the same information and)-.18 E
(serve the same purpose as with)93.6 372 Q F1(NORM_DATA)2.5 E F0(and)2.5
E F1(NORM_INFO)2.5 E F0 2.5(messages. The)2.5 F("flavor" field)2.5 E
(indicates the type of command to follow)93.6 384 Q 5(.T)-.92 G(he r)-5
E(emainder of the)-.18 E F1(NORM_CMD)2.5 E F0(message is)2.5 E
(dependent upon the command type \("flavor"\).)93.6 396 Q
(NORM command flavors include:)5 E .4 LW 501.905 418.5 74.095 418.5 DL
51.93(Command Flavor)118.525 428 R(Purpose)109.63 E 501.905 432.5 74.095
432.5 DL F1(NORM_CMD\(FLUSH\))79.095 442 Q F0(1)62.765 E
(Used to indicate sender temporary end-of-)263.625 442 Q 2.5
(transmission. \(Assists)263.625 454 R(in r)2.5 E(obustly initiating)
-.18 E(outstanding r)263.625 466 Q(epair r)-.18 E(equests fr)-.18 E
(om r)-.18 E 2.5(eceivers\). May)-.18 F
(also be optionally used to collect positive)263.625 478 Q
(acknowledgment of r)263.625 490 Q(eliable r)-.18 E(eception fr)-.18 E
(om subset of)-.18 E -.18(re)263.625 502 S(ceivers.).18 E 501.905 506.5
74.095 506.5 DL F1(NORM_CMD\(EOT\))79.095 516 Q F0(2)74.765 E
(Used to indicate sender permanent end-of-)263.625 516 Q(transmission.)
263.625 528 Q 501.905 532.5 74.095 532.5 DL F1(NORM_CMD\(SQUELCH\))
79.095 542 Q F0(3)50.765 E(Used to advertise sender)263.625 542 Q
('s curr).74 E(ent r)-.18 E(epair window in)-.18 E -.18(re)263.625 554 S
(sponse to out-of-range NACKs fr).18 E(om r)-.18 E(eceivers.)-.18 E
501.905 558.5 74.095 558.5 DL F1(NORM_CMD\(CC\))79.095 568 Q F0(4)80.765
E(Used for GR)263.625 568 Q(TT measur)-.37 E(ement and collection of)
-.18 E(congestion contr)263.625 580 Q(ol feedback.)-.18 E 501.905 584.5
74.095 584.5 DL F1(NORM_CMD\(REPAIR_ADV\))79.095 594 Q F0(5)32.765 E
(Used to advertise sender)263.625 594 Q('s aggr).74 E(egated)-.18 E -.18
(re)263.625 606 S(pair/feedback state for suppr).18 E(ession of unicast)
-.18 E(feedback fr)263.625 618 Q(om r)-.18 E(eceivers.)-.18 E 501.905
622.5 74.095 622.5 DL F1(NORM_CMD\(ACK_REQ\))79.095 632 Q F0(6)50.765 E
(Used to r)263.625 632 Q(equest application-defined positive)-.18 E
(acknowledgment fr)263.625 644 Q(om a list of r)-.18 E(eceivers)-.18 E
(\(OPTIONAL\).)263.625 656 Q 501.905 660.5 74.095 660.5 DL F1
(NORM_CMD\(APPLICATION\))79.095 670 Q F0(7)26.765 E
(Used for application-defined purposes which may)263.625 670 Q
(need to temporarily pr)263.625 682 Q(eempt data transmission)-.18 E
(\(OPTIONAL\).)263.625 694 Q 501.905 698.5 74.095 698.5 DL 501.905 418.5
501.905 698.5 DL 74.095 418.5 74.095 698.5 DL 256.125 418.5 256.125
698.5 DL 212.595 418.5 212.595 698.5 DL(Adamson, et al.)72 768 Q(Expir)
87.875 E(es: 31 December 2007)-.18 E([Page 24])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Palatino-Bold@0 SF 2.5
(4.2.3.1. NORM_CMD\(FLUSH\))72 120 R(Message)2.5 E F0(The)93.6 135.6 Q
/F2 10/Courier@0 SF(NORM_CMD\(FLUSH\))2.5 E F0
(command is sent when the sender r)2.5 E(eaches the end of all data)-.18
E(content and pending r)93.6 147.6 Q
(epairs it has queued for transmission.)-.18 E
(This may indicate a temporary)5 E(or permanent end of data transmissio\
n, but the sender is still willing to r)93.6 159.6 Q(espond to r)-.18 E
(epair)-.18 E -.18(re)93.6 171.6 S 2.5(quests. This).18 F(command is r)
2.5 E(epeated once per)-.18 E F2(2*GRTT)2.5 E F0(to excite the r)2.5 E
(eceiver set for any)-.18 E(outstanding r)93.6 183.6 Q(epair r)-.18 E(e\
quests up to and including the transmission point indicated within the)
-.18 E F2(NORM_CMD\(FLUSH\))93.6 195.6 Q F0 2.5(message. The)2.5 F
(number of r)2.5 E(epeats is equal to)-.18 E F2(NORM_ROBUST_FACTOR)2.5 E
F0(unless a list of r)93.6 207.6 Q(eceivers fr)-.18 E
(om which explicit positive acknowledgment is expected)-.18 E
(\("acking_node_list"\) is given.)93.6 219.6 Q
(In that case, the "acking_node_list" is updated as)5 E
(acknowledgments ar)93.6 231.6 Q 2.5(er)-.18 G(eceived and the)-2.68 E
F2(NORM_CMD\(FLUSH\))2.5 E F0(is r)2.5 E(epeated accor)-.18 E
(ding to the)-.18 E(mechanism described in Section 5.5.3.)93.6 243.6 Q
(The gr)5 E(eater the)-.18 E F2(NORM_ROBUST_FACTOR)2.5 E F0 2.5(,t)C
(he gr)-2.5 E(eater)-.18 E(the pr)93.6 255.6 Q
(obability that all applicable r)-.18 E
(eceivers will be excited for acknowledgment or r)-.18 E(epair)-.18 E
-.18(re)93.6 267.6 S(quests \(NACKs\) _and_ that the corr).18 E
(esponding NACKs ar)-.18 E 2.5(ed)-.18 G(eliver)-2.5 E(ed to the sender)
-.18 E 5(.A)-.74 G(default value of)93.6 279.6 Q F2(NORM_ROBUST_FACTOR)
2.5 E F0(equal to 20 is RECOMMENDED.)2.5 E(If a)5 E F2(NORM_NACK)2.5 E
F0(message interr)93.6 291.6 Q(upts the flush pr)-.08 E
(ocess, the sender SHALL r)-.18 E(e-initiate the flush pr)-.18 E
(ocess after)-.18 E(any r)93.6 303.6 Q(esulting r)-.18 E
(epair transmissions ar)-.18 E 2.5(ec)-.18 G(ompleted.)-2.5 E
(Note that r)93.6 327.6 Q(eceivers also employ a timeout mechanism to s\
elf-initiate NACKing \(if ther)-.18 E 2.5(ea)-.18 G -.18(re)-2.5 G
(outstanding r)93.6 339.6 Q
(epair needs\) when no messages of any type ar)-.18 E 2.5(er)-.18 G
(eceived fr)-2.68 E(om a sender)-.18 E 5(.T)-.74 G(his)-5 E
(inactivity timeout is r)93.6 351.6 Q(elated to the)-.18 E F2
(NORM_CMD\(FLUSH\))2.5 E F0(and)2.5 E F2(NORM_ROBUST_FACTOR)2.5 E F0
(and is)2.5 E(specified in Section 5.3.)93.6 363.6 Q
(Receivers SHALL self-initiate the NACK r)5 E(epair pr)-.18 E
(ocess when the)-.18 E(inactivity has expir)93.6 375.6 Q
(ed for a specific sender and the r)-.18 E(eceiver has pending r)-.18 E
(epairs needed fr)-.18 E(om)-.18 E(that sender)93.6 387.6 Q 5(.W)-.74 G
(ith a suf)-5.55 E(ficiently lar)-.18 E(ge)-.18 E F2(NORM_ROBUST_FACTOR)
2.5 E F0(value, data content is)2.5 E(deliver)93.6 399.6 Q
(ed with a high assurance of r)-.18 E(eliability)-.18 E 5(.T)-1.11 G
(he penalty of a lar)-5 E(ge)-.18 E F2(NORM_ROBUST_FACTOR)2.5 E F0
(value is the potential transmission of excess)93.6 411.6 Q F2
(NORM_CMD\(FLUSH\))2.5 E F0(messages and a longer)2.5 E
(inactivity timeout for r)93.6 423.6 Q
(eceivers to self-initiate a terminal NACK pr)-.18 E(ocess.)-.18 E
(For finite-size transport objects such as)93.6 447.6 Q F2
(NORM_OBJECT_DATA)2.5 E F0(and)2.5 E F2(NORM_OBJECT_FILE)2.5 E F0 2.5
(,t)C(he)-2.5 E(flush pr)93.6 459.6 Q(ocess \(if ther)-.18 E 2.5(ea)-.18
G .36 -.18(re n)-2.5 H 2.5(of).18 G
(urther pending objects\) occurs at the end of these objects.)-2.5 E
(Thus, FEC r)93.6 471.6 Q(epair information is always available for r)
-.18 E(epairs in r)-.18 E(esponse to r)-.18 E(epair r)-.18 E(equests)
-.18 E(elicited by the flush command.)93.6 483.6 Q(However)5 E 2.5(,f)
-.74 G(or)-2.5 E F2(NORM_OBJECT_STREAM)2.5 E F0 2.5(,t)C
(he flush may occur)-2.5 E(at any time, including in the middle of an F\
EC coding block if systematic FEC codes ar)93.6 495.6 Q(e)-.18 E 2.5
(employed. In)93.6 507.6 R
(this case, the sender will not yet be able to pr)2.5 E
(ovide FEC parity content for the)-.18 E(concurr)93.6 519.6 Q
(ent coding block and will be limited to explicitly r)-.18 E
(epairing the str)-.18 E(eam with sour)-.18 E(ce)-.18 E
(data content for that block.)93.6 531.6 Q
(Applications that anticipate fr)5 E(equent flushing of str)-.18 E
(eam content)-.18 E(SHOULD be judicious in the selection of the FEC cod\
ing block size \(i.e., do not use a very)93.6 543.6 Q(lar)93.6 555.6 Q
(ge coding block size if fr)-.18 E(equent flushing occurs\).)-.18 E
(For example, a r)5 E(eliable multicast)-.18 E
(application transmitting an on-going series of intermittent, r)93.6
567.6 Q(elatively small messages will)-.18 E(need to trade-of)93.6 579.6
Q 2.5(fu)-.18 G(sing the)-2.5 E F2(NORM_OBJECT_DATA)2.5 E F0
(paradigm versus the)2.5 E F2(NORM_OBJECT_STREAM)93.6 591.6 Q F0
(paradigm with an appr)2.5 E(opriate FEC coding block size.)-.18 E
(This is)5 E(analogous to application trade-of)93.6 603.6 Q
(fs for other transport pr)-.18 E(otocols such as the selection of)-.18
E(dif)93.6 615.6 Q(fer)-.18 E
(ent TCP modes of operation such as "no delay", etc.)-.18 E
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q(|version| type=3|)93.6 156 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 162(|s)93.6 180 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 60(|i)93.6 204 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 18(|f)93.6 228 S(lavor = 1)-18 E 24(|f)12 G 24(ec_id |)-24 F 30
(object_transport_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
240 Q 150(|f)93.6 252 S 138(ec_payload_id |)-150 F 180(|.)93.6 264 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
276 Q 96(|a)93.6 288 S(cking_node_list \(if applicable\))-96 E(|)90 E
180(|.)93.6 300 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
312 Q/F2 10/Palatino-Italic@0 SF(NORM_CMD\(FLUSH\) Message Format)214.63
336 Q F0(The "version", "type", "hdr_len", "sequence", and "sour)93.6
360 Q(ce_id" fields form the NORM)-.18 E
(Common Message Header as described in Section 4.1.)93.6 372 Q
(In addition to the NORM common)5 E(message header and standar)93.6 384
Q(d)-.18 E F1(NORM_CMD)2.5 E F0(fields, the)2.5 E F1(NORM_CMD\(FLUSH\))
2.5 E F0(message contains)2.5 E(fields to identify the curr)93.6 396 Q
(ent status and logical transmit position of the sender)-.18 E(.)-.74 E
(The "fec_id" field indicates the FEC type used for the flushing "objec\
t_transport_id" and)93.6 420 Q
(implies the size and format of the "fec_payload_id" field.)93.6 432 Q
(Note the "hdr_len" value for the)5 E F1(NORM_CMD\(FLUSH\))93.6 444 Q F0
(message is 4 plus the size of the "fec_payload_id" field when no heade\
r)2.5 E(extensions ar)93.6 456 Q 2.5(ep)-.18 G -.18(re)-2.5 G(sent.).18
E(The "object_transport_id" and "fec_payload_id" fields indicate the se\
nder)93.6 480 Q('s curr).74 E(ent logical)-.18 E("transmit position".)
93.6 492 Q(These fields ar)5 E 2.5(ei)-.18 G(nterpr)-2.5 E
(eted in the same manner as in the)-.18 E F1(NORM_DATA)2.5 E F0
(message type.)93.6 504 Q(Upon r)5 E(eceipt of the)-.18 E F1
(NORM_CMD\(FLUSH\))2.5 E F0 2.5(,r)C(eceivers ar)-2.68 E 2.5(ee)-.18 G
(xpected to check their)-2.5 E(completion state _thr)93.6 516 Q
(ough_ \(including\) this transmission position.)-.18 E(If r)5 E
(eceivers have)-.18 E(outstanding r)93.6 528 Q
(epair needs in this range, they SHALL initiate the NORM NACK Repair)
-.18 E(Pr)93.6 540 Q(ocess as described in Section 5.3.)-.18 E(If r)5 E
(eceivers have no outstanding r)-.18 E(epair needs, no)-.18 E -.18(re)
93.6 552 S(sponse to the).18 E F1(NORM_CMD\(FLUSH\))2.5 E F0
(is generated.)2.5 E(For)93.6 576 Q F1(NORM_OBJECT_STREAM)2.5 E F0
(objects using systematic FEC codes, r)2.5 E(eceivers MUST r)-.18 E
(equest)-.18 E("explicit-only" r)93.6 588 Q
(epair of the identified "sour)-.18 E(ce_block_number" if the given)-.18
E("encoding_symbol_id" is less than the "sour)93.6 600 Q 2.5
(ce_block_len". This)-.18 F(condition indicates the)2.5 E
(sender has not yet completed encoding the corr)93.6 612 Q
(esponding FEC block and parity content is)-.18 E(not yet available.)
93.6 624 Q(An "explicit-only" r)5 E(epair r)-.18 E
(equest consists of NACK content for the)-.18 E(applicable "sour)93.6
636 Q(ce_block_number" which does not include any r)-.18 E
(equests for parity-based)-.18 E -.18(re)93.6 648 S(pair).18 E 5(.T)-.74
G(his allows NORM sender applications to "flush" an ongoing str)-5 E
(eam of transmission)-.18 E
(when needed, even if in the middle of an FEC block.)93.6 660 Q
(Once the sender r)5 E(esumes str)-.18 E(eam)-.18 E(transmission and pa\
sses the end of the pending coding block, subsequent NACKs fr)93.6 672 Q
(om)-.18 E -.18(re)93.6 684 S(ceivers SHALL r).18 E
(equest parity-based r)-.18 E(epair as usual.)-.18 E
(Note that the use of a systematic FEC)5 E(code is assumed her)93.6 696
Q 2.5(e. It)-.18 F
(should also be noted that a sender has the option of arbitrarily)2.5 E
(shortening a given code block when such an application "flush" occurs.)
93.6 708 Q(In this case, the)5 E -.18(re)93.6 720 S(ceiver will r).18 E
(equest explicit r)-.18 E(epair)-.18 E 2.5(,b)-.74 G(ut the sender MA)
-2.5 E 2.5(Yp)-1.11 G -.18(ro)-2.5 G(vide FEC-based r).18 E
(epair \(parity)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(segments\) in r)93.6 120 Q 2.5
(esponse. These)-.18 F(parity segments MUST contain the corr)2.5 E
(ected)-.18 E("sour)93.6 132 Q
(ce_block_len" for the shortened block and that "sour)-.18 E
(ce_block_len" associated with)-.18 E
(segments containing parity content SHALL overrride the pr)93.6 144 Q
(eviously advertised)-.18 E("sour)93.6 156 Q 2.5
(ce_block_len". Similarly)-.18 F 2.5(,t)-1.11 G(he "sour)-2.5 E
(ce_block_len" associated with the highest or)-.18 E(dinal)-.18 E
("encoding_symbol_id" shall take pr)93.6 168 Q
(ecedence over prior symbols when a dif)-.18 E(fer)-.18 E
(ence \(e.g., due)-.18 E(to code shortening at the sender\) occurs.)93.6
180 Q(Normal r)5 E(eceiver NACK initiation and constr)-.18 E(uction)-.08
E(is discussed in detail in Section 5.3.)93.6 192 Q
(The OPTIONAL "acking_node_list" field contains a list)5 E(of)93.6 204 Q
/F1 10/Palatino-Italic@0 SF(NormNodeIds)2.5 E F0(for r)2.5 E
(eceivers fr)-.18 E(om which the sender is r)-.18 E
(equesting explicit positive)-.18 E(acknowledgment of r)93.6 216 Q
(eception up thr)-.18 E(ough the transmission point identified by the)
-.18 E("object_transport_id" and "fec_payload_id" fields.)93.6 228 Q
(The length of the list can be inferr)5 E(ed fr)-.18 E(om)-.18 E
(the length of the r)93.6 240 Q(eceived)-.18 E/F2 10/Courier@0 SF
(NORM_CMD\(FLUSH\))2.5 E F0 2.5(message. When)2.5 F
(the "acking_node_list" is)2.5 E(pr)93.6 252 Q
(esent, the lightweight positive acknowledgment pr)-.18 E
(ocess described in Section 5.5.3 SHALL)-.18 E(be observed.)93.6 264 Q
/F3 10/Palatino-Bold@0 SF 2.5(4.2.3.2. NORM_CMD\(EOT\))72 300 R(Message)
2.5 E F0(The)93.6 315.6 Q F2(NORM_CMD\(EOT\))2.5 E F0
(command is sent when the sender r)2.5 E(eaches permanent end-of-)-.18 E
(transmission with r)93.6 327.6 Q(espect to the)-.18 E F1(NormSession)
2.5 E F0(and will not r)2.5 E(espond to further r)-.18 E(epair r)-.18 E
(equests.)-.18 E(This allows r)93.6 339.6 Q(eceivers to gracefully r)
-.18 E(each closur)-.18 E 2.5(eo)-.18 G 2.5(fo)-2.5 G
(peration with this sender \(without)-2.5 E -.18(re)93.6 351.6 S
(quiring any timeout\) and fr).18 E(ee any r)-.18 E(esour)-.18 E
(ces that ar)-.18 E 2.5(en)-.18 G 2.5(ol)-2.5 G(onger needed.)-2.5 E
(The)5 E F2(NORM_CMD\(EOT\))93.6 363.6 Q F0
(command SHOULD be sent with the same r)2.5 E
(obust mechanism as used for)-.18 E F2(NORM_CMD\(FLUSH\))93.6 375.6 Q F0
(commands to pr)2.5 E(ovide a high assurance of r)-.18 E
(eception by the r)-.18 E(eceiver set.)-.18 E F2 114(0123)99.6 399.6 S 6
(01234567890123456789012345678901)99.6 411.6 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
423.6 Q(|version| type=3|)93.6 435.6 Q 18(hdr_len |)24 F 72(sequence |)
60 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
93.6 447.6 Q 162(|s)93.6 459.6 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
471.6 Q 60(|i)93.6 483.6 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
495.6 Q 18(|f)93.6 507.6 S(lavor = 2)-18 E 120(|r)12 G 108(eserved |)
-120 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
519.6 Q F1(NORM_CMD\(EOT\) Message Format)220.75 543.6 Q F0
(The value of the "hdr_len" field for)93.6 567.6 Q F2(NORM_CMD\(EOT\))
2.5 E F0(messages without header extensions)2.5 E(pr)93.6 579.6 Q
(esent is 4.)-.18 E(The "r)5 E(eserved" field is r)-.18 E
(eserved for futur)-.18 E 2.5(eu)-.18 G
(se and MUST be set to an all ZERO)-2.5 E 2.5(value. Receivers)93.6
591.6 R(MUST ignor)2.5 E 2.5(et)-.18 G(he "r)-2.5 E(eserved" field.)-.18
E F3 2.5(4.2.3.3. NORM_CMD\(SQUELCH\))72 627.6 R(Message)2.5 E F0(The)
93.6 643.2 Q F2(NORM_CMD\(SQUELCH\))2.5 E F0
(command is transmitted in r)2.5 E(esponse to outdated or invalid)-.18 E
F2(NORM_NACK)93.6 655.2 Q F0(content r)2.5 E(eceived by the sender)-.18
E 5(.I)-.74 G(nvalid)-5 E F2(NORM_NACK)2.5 E F0(content consists of r)
2.5 E(epair)-.18 E -.18(re)93.6 667.2 S(quests for).18 E F1(NormObjects)
2.5 E F0(for which the sender is unable or unwilling to pr)2.5 E
(ovide r)-.18 E(epair)-.18 E 5(.T)-.74 G(his)-5 E(includes r)93.6 679.2
Q(epair r)-.18 E(equests for outdated objects, aborted objects, or thos\
e objects which the)-.18 E(sender pr)93.6 691.2 Q
(eviously transmitted marked with the)-.18 E F2(NORM_FLAG_UNRELIABLE)2.5
E F0 2.5(flag. This)2.5 F(command indicates to r)93.6 703.2 Q
(eceivers what content is available for r)-.18 E(epair)-.18 E 2.5(,t)
-.74 G(hus serving as a)-2.5 E(description of the sender)93.6 715.2 Q
('s curr).74 E(ent "r)-.18 E(epair window".)-.18 E
(Receivers SHALL not generate r)5 E(epair)-.18 E(Adamson, et al.)72 768
Q(Expir)87.875 E(es: 31 December 2007)-.18 E([Page 27])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E -.18(re)93.6 120 S
(quests for content identified as invalid by a).18 E/F1 10/Courier@0 SF
(NORM_CMD\(SQUELCH\))2.5 E F0(.)A(The)93.6 144 Q F1(NORM_CMD\(SQUELCH\))
2.5 E F0(command is sent once per)2.5 E F1(2*GRTT)2.5 E F0(at the most.)
2.5 E(The)5 E F1(NORM_CMD\(SQUELCH\))93.6 156 Q F0(advertises the curr)
2.5 E(ent "r)-.18 E(epair window" of the sender by identifying)-.18 E
(the earliest \(lowest\) transmission point for which it will pr)93.6
168 Q(ovide r)-.18 E(epair)-.18 E 2.5(,a)-.74 G(long with an)-2.5 E
(encoded list of objects fr)93.6 180 Q(om that point forwar)-.18 E 2.5
(dt)-.18 G(hat ar)-2.5 E 2.5(en)-.18 G 2.5(ol)-2.5 G(onger valid for r)
-2.5 E(epair)-.18 E 5(.T)-.74 G(his)-5 E(mechanism allows the sender ap\
plication to cancel or abort transmission and/or r)93.6 192 Q(epair of)
-.18 E(specific pr)93.6 204 Q(eviously enqueued objects.)-.18 E
(The list also contains the identifiers for any objects)5 E
(within the r)93.6 216 Q(epair window that wer)-.18 E 2.5(es)-.18 G
(ent with the)-2.5 E F1(NORM_FLAG_UNRELIABLE)2.5 E F0(flag set.)2.5 E
(In)5 E(normal conditions, it is expected the)93.6 228 Q F1
(NORM_CMD\(SQUELCH\))2.5 E F0(will be needed infr)2.5 E(equently)-.18 E
2.5(,a)-1.11 G(nd)-2.5 E(generally only to pr)93.6 240 Q(ovide a r)-.18
E(efer)-.18 E(ence r)-.18 E(epair window for r)-.18 E
(eceivers who have fallen "out-of-)-.18 E
(sync" with the sender due to extr)93.6 252 Q
(emely poor network conditions.)-.18 E
(The starting point of the invalid)93.6 276 Q/F2 10/Palatino-Italic@0 SF
(NormObject)2.5 E F0(list begins with the lowest invalid)2.5 E F2(NormT)
93.6 288 Q(ransportId)-1.11 E F0(gr)2.5 E(eater than the curr)-.18 E
(ent "r)-.18 E(epair window" start fr)-.18 E(om the invalid NACK\(s\))
-.18 E(that pr)93.6 300 Q(ompted the generation of the squelch.)-.18 E
(The length of the list is limited by the sender)5 E('s).74 E F2
(NormSegmentSize)93.6 312 Q F0 5(.T)C(his allows the r)-5 E
(eceivers to learn the status of the sender)-.18 E('s applicable).74 E
(object r)93.6 324 Q(epair window with minimal transmission of)-.18 E F1
(NORM_CMD\(SQUELCH\))2.5 E F0 2.5(commands. The)2.5 F(format of the)93.6
336 Q F1(NORM_CMD\(SQUELCH\))2.5 E F0(message is:)2.5 E F1 114(0123)99.6
360 S 6(01234567890123456789012345678901)99.6 372 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
384 Q(|version| type=3|)93.6 396 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
408 Q 162(|s)93.6 420 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
432 Q 60(|i)93.6 444 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
456 Q 12(|f)93.6 468 S(lavor = 3)-12 E 30(|f)18 G 18(ec_id |)-30 F 30
(object_transport_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
480 Q 150(|f)93.6 492 S 138(ec_payload_id |)-150 F 180(|.)93.6 504 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
516 Q 144(|i)93.6 528 S 114(nvalid_object_list |)-144 F 180(|.)93.6 540
S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
552 Q F2(NORM_CMD\(SQUELCH\) Message Format)207.13 576 Q F0
(In addition to the NORM common message header and standar)93.6 600 Q(d)
-.18 E F1(NORM_CMD)2.5 E F0(fields, the)2.5 E F1(NORM_CMD\(SQUELCH\))
93.6 612 Q F0
(message contains fields to identify the earliest logical transmit)2.5 E
(position of the sender)93.6 624 Q('s curr).74 E(ent r)-.18 E
(epair window and an "invalid object list" beginning with)-.18 E
(the index of the logically earliest invalid r)93.6 636 Q(epair r)-.18 E
(equest fr)-.18 E(om the of)-.18 E(fending NACK message)-.18 E
(which initiated the squelch transmission.)93.6 648 Q
(The value of the "hdr_len" field when no)5 E(extensions ar)93.6 660 Q
2.5(ep)-.18 G -.18(re)-2.5 G(sent is 4 plus the size of the "fec_payloa\
d_id" field that is dependent upon).18 E
(the FEC scheme identified by the "fec_id" field.)93.6 672 Q
(The "object_transport_id" and "fec_payload_id" fields ar)93.6 696 Q 2.5
(ec)-.18 G(oncatenated to indicate the)-2.5 E(beginning of the sender)
93.6 708 Q('s curr).74 E(ent r)-.18 E
(epair window \(i.e., the logically earliest point in its)-.18 E
(transmission history for which the sender can pr)93.6 720 Q(ovide r)
-.18 E 2.5(epair\). The)-.18 F("fec_id" field implies the)2.5 E
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(size and format of the "fec_payload_id" field.)93.6 120 Q
(This serves as an advertisement of a)5 E("synchr)93.6 132 Q
(onization point" for r)-.18 E(eceivers to r)-.18 E(equest r)-.18 E
(epair)-.18 E 5(.N)-.74 G(ote, that while an)-5 E("encoding_symbol_id" \
may be included in the "fec_payload_id" field, the sender)93.6 144 Q
('s r).74 E(epair)-.18 E
(window SHOULD be aligned on FEC coding block boundaries and thus the)
93.6 156 Q("encoding_symbol_id" SHOULD be zer)93.6 168 Q(o.)-.18 E
(The "invalid_object_list" is a list of 16-bit)93.6 192 Q/F1 10
/Palatino-Italic@0 SF(NormT)2.5 E(ransportIds)-1.11 E F0
(that, although they ar)2.5 E 2.5(ew)-.18 G(ithin the)-2.5 E
(range of the sender)93.6 204 Q('s curr).74 E(ent r)-.18 E(epair window)
-.18 E 2.5(,a)-.92 G .36 -.18(re n)-2.5 H 2.5(ol).18 G
(onger available for r)-2.5 E(epair fr)-.18 E(om the)-.18 E(sender)93.6
216 Q 5(.F)-.74 G(or example, a sender application may dequeue an out-o\
f-date object even though it)-5 E(is still within the r)93.6 228 Q
(epair window)-.18 E 5(.T)-.92 G
(he total size of the "invalid_object_list" content is can be)-5 E
(determined fr)93.6 240 Q
(om the packet's payload length and is limited to a maximum of the)-.18
E F1(NormSegmentSize)93.6 252 Q F0(of the sender)2.5 E 5(.T)-.74 G
(hus, for very lar)-5 E(ge r)-.18 E
(epair windows, it is possible that a)-.18 E(single)93.6 264 Q/F2 10
/Courier@0 SF(NORM_CMD\(SQUELCH\))2.5 E F0
(message may not be capable of listing the entir)2.5 E 2.5(es)-.18 G
(et of invalid)-2.5 E(objects in the r)93.6 276 Q(epair window)-.18 E 5
(.I)-.92 G 2.5(nt)-5 G(his case, the sender SHALL ensur)-2.5 E 2.5(et)
-.18 G(hat the list begins with)-2.5 E(a)93.6 288 Q F1(NormObjectId)2.5
E F0(that is gr)2.5 E(eater than or equal to the lowest or)-.18 E
(dinal invalid)-.18 E F1(NormObjectId)2.5 E F0(fr)2.5 E(om)-.18 E
(the NACK message\(s\) that pr)93.6 300 Q(ompted the)-.18 E F2
(NORM_CMD\(SQUELCH\))2.5 E F0 2.5(generation. The)2.5 F F1
(NormObjectIds)93.6 312 Q F0(in the "invalid_object_list" MUST be gr)2.5
E(eater than the "object_transport_id")-.18 E
(marking the beginning of the sender)93.6 324 Q('s r).74 E(epair window)
-.18 E 5(.T)-.92 G(his insur)-5 E(es conver)-.18 E(gence of the)-.18 E
(squelch pr)93.6 336 Q
(ocess, even if multiple invalid NACK/ squelch iterations ar)-.18 E 2.5
(er)-.18 G(equir)-2.68 E 2.5(ed. This)-.18 F
(explicit description of invalid content within the sender)93.6 348 Q
('s curr).74 E(ent window allows the sender)-.18 E
(application \(most notably for discr)93.6 360 Q
(ete "object" based transport\) to arbitrarily invalidate \(i.e.,)-.18 E
(dequeue\) portions of enqueued content \(e.g., certain objects\) for w\
hich it no longer wishes to)93.6 372 Q(pr)93.6 384 Q(ovide r)-.18 E
(eliable transport.)-.18 E/F3 10/Palatino-Bold@0 SF 2.5
(4.2.3.4. NORM_CMD\(CC\))72 420 R(Message)2.5 E F0(The)93.6 435.6 Q F2
(NORM_CMD\(CC\))2.5 E F0(messages contains fields to enable sender)2.5 E
(-to-r)-.18 E(eceiver gr)-.18 E(oup gr)-.18 E(eatest)-.18 E -.18(ro)93.6
447.6 S(und-trip time \(GR).18 E(TT\) measur)-.37 E
(ement and to excite the gr)-.18 E(oup for congestion contr)-.18 E(ol)
-.18 E 2.5(feedback. A)93.6 459.6 R(baseline NORM congestion contr)2.5 E
(ol scheme \(NORM-CC\), based on the TCP-)-.18 E
(Friendly Multicast Congestion Contr)93.6 471.6 Q
(ol \(TFMCC\) scheme of [5] is described in Section 5.5.2)-.18 E
(of this document.)93.6 483.6 Q(The)5 E F2(NORM_CMD\(CC\))2.5 E F0
(message is usually transmitted as part of NORM-CC)2.5 E
(congestion contr)93.6 495.6 Q(ol operation.)-.18 E 2.5(AN)5 G
(ORM header extension is defined below to be used with)-2.5 E(the)93.6
507.6 Q F2(NORM_CMD\(CC\))2.5 E F0
(message to support NORM-CC operation.)2.5 E(Dif)5 E(fer)-.18 E
(ent header extensions)-.18 E(may be defined for the)93.6 519.6 Q F2
(NORM_CMD\(CC\))2.5 E F0(\(and/or other NORM messages as needed\) to)2.5
E(support alternative congestion contr)93.6 531.6 Q
(ol schemes in the futur)-.18 E 2.5(e. If)-.18 F(NORM is operated in a)
2.5 E(private network with congestion contr)93.6 543.6 Q
(ol operation disabled, the)-.18 E F2(NORM_CMD\(CC\))2.5 E F0
(message is)2.5 E(then used for GR)93.6 555.6 Q(TT measur)-.37 E
(ement only and may optionally be sent less fr)-.18 E
(equently than with)-.18 E(congestion contr)93.6 567.6 Q(ol operation.)
-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q(|version| type=3|)93.6 156 Q 18(hdr_len |)24 F 60(sequence |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 162(|s)93.6 180 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 60(|i)93.6 204 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 18(|f)93.6 228 S(lavor = 4)-18 E 24(|r)12 G 12(eserved |)-24 F 54
(cc_sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
240 Q 150(|s)93.6 252 S 144(end_time_sec |)-150 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
264 Q 144(|s)93.6 276 S 144(end_time_usec |)-144 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
288 Q 90(|h)93.6 300 S(eader extensions \(if applicable\))-90 E(|)90 E
180(|.)93.6 312 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
324 Q 108(|c)93.6 336 S(c_node_list \(if applicable\))-108 E(|)102 E 180
(|.)93.6 348 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
360 Q/F2 10/Palatino-Italic@0 SF(NORM_CMD\(CC\) Message Format)224.08
384 Q F0(The NORM common message header and standar)93.6 408 Q(d)-.18 E
F1(NORM_CMD)2.5 E F0(fields serve their usual)2.5 E 2.5(purposes. The)
93.6 420 R(value of the "hdr_len" field when no header extensions ar)2.5
E 2.5(ep)-.18 G -.18(re)-2.5 G(sent is 6.).18 E(The "r)93.6 444 Q
(eserved" field is for potential futur)-.18 E 2.5(eu)-.18 G
(se and MUST be set to ZERO in this version of)-2.5 E(the NORM pr)93.6
456 Q(otocol and its baseline NORM-CC congestion contr)-.18 E
(ol scheme.)-.18 E(It may be)5 E
(possible that alternative congestion contr)93.6 468 Q
(ol schemes may use the)-.18 E F1(NORM_CMD\(CC\))2.5 E F0(message)2.5 E
(defined her)93.6 480 Q 2.5(ea)-.18 G(nd leverage the "r)-2.5 E
(eserved" field for scheme-specific purposes.)-.18 E
(The "cc_sequence" field is a sequence number applied by the sender)93.6
504 Q 5(.F)-.74 G(or NORM-CC)-5 E(operation, it is used to pr)93.6 516 Q
(ovide functionality equivalent to the "feedback r)-.18 E(ound number")
-.18 E(\()93.6 528 Q F1(fb_nr)A F0(\)described in [5].)A(The most r)5 E
(ecently r)-.18 E(eceived "cc_sequence" value is r)-.18 E(ecor)-.18 E
(ded by)-.18 E -.18(re)93.6 540 S
(ceivers and can be fed back to the sender in congestion contr).18 E
(ol feedback generated by the)-.18 E -.18(re)93.6 552 S
(ceivers for that sender).18 E 5(.T)-.74 G
(he "cc_sequence" number can also be used in NORM)-5 E
(implementations to assess how r)93.6 564 Q(ecently a r)-.18 E
(eceiver has r)-.18 E(eceived)-.18 E F1(NORM_CMD\(CC\))2.5 E F0(pr)2.5 E
(obes fr)-.18 E(om)-.18 E(the sender)93.6 576 Q 5(.T)-.74 G
(his can be useful instr)-5 E
(umentation for complex or experimental multicast)-.08 E -.18(ro)93.6
588 S(uting envir).18 E(onments.)-.18 E
(The "send_time" field is a timestamp indicating the time that the)93.6
612 Q F1(NORM_CMD\(CC\))2.5 E F0(message)2.5 E(was transmitted.)93.6 624
Q(This consists of a 64-bit field containing 32-bits with the time in s\
econds)5 E(\("send_time_sec"\) and 32-bits with the time in micr)93.6
636 Q(oseconds \("send_time_usec"\) since some)-.18 E -.18(re)93.6 648 S
(fer).18 E(ence time the sour)-.18 E
(ce maintains \(usually 00:00:00, 1 January 1970\).)-.18 E(The byte or)5
E(dering of)-.18 E(the fields is "Big Endian" network or)93.6 660 Q(der)
-.18 E 5(.R)-.74 G(eceivers use this timestamp adjusted by the)-5 E
(amount of delay fr)93.6 672 Q(om the time they r)-.18 E(eceived the)
-.18 E F1(NORM_CMD\(CC\))2.5 E F0(message to the time of)2.5 E(their r)
93.6 684 Q(esponse as the "grtt_r)-.18 E(esponse" portion of)-.18 E F1
(NORM_ACK)2.5 E F0(and)2.5 E F1(NORM_NACK)2.5 E F0(messages)2.5 E 2.5
(generated. This)93.6 696 R(allows the sender to evaluate r)2.5 E
(ound-trip times to dif)-.18 E(fer)-.18 E(ent r)-.18 E(eceivers for)-.18
E(congestion contr)93.6 708 Q(ol and other \(e.g., GR)-.18 E
(TT determination\) purposes.)-.37 E(Adamson, et al.)72 768 Q(Expir)
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E 1.84 -.92(To f)93.6 120 T(acil\
itate the baseline NORM-CC scheme described in Section 5.5.2, a NORM-CC\
 Rate).92 E(header extension \(EXT_RA)93.6 132 Q
(TE\) is defined to inform the gr)-.74 E(oup of the sender)-.18 E
('s curr).74 E(ent)-.18 E(transmission rate.)93.6 144 Q(This is used al\
ong with the loss detection "sequence" field of all NORM)5 E
(sender messages and the)93.6 156 Q/F1 10/Courier@0 SF(NORM_CMD\(CC\))
2.5 E F0(GR)2.5 E(TT collection pr)-.37 E(ocess to support NORM-CC)-.18
E(congestion contr)93.6 168 Q(ol operation.)-.18 E
(The format of this header extension is as follows:)5 E F1 114(0123)99.6
192 S 6(01234567890123456789012345678901)99.6 204 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 24(|h)93.6 228 S(et = 128)-24 E 24(|r)12 G 12(eserved |)-24 F 60
(send_rate |)66 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
240 Q/F2 10/Palatino-Italic@0 SF
(NORM-CC Rate Header Extension Format \(EXT_RA)181.44 264 Q(TE\))-.55 E
F0(The "send_rate" field indicates the sender)93.6 288 Q('s curr).74 E
(ent transmission rate in bytes per second.)-.18 E(The 16-bit "send_rat\
e" field consists of 12 bits of mantissa in the most significant portio\
n and)93.6 300 Q 2.5(4b)93.6 312 S(its of base 10 integer exponent \(E\
\) information in the least significant portion.)-2.5 E(The 12-bit)5 E(\
mantissa portion of the field is scaled such that a base 10 mantissa \(\
M\) floating point value)93.6 324 Q(of 0.0 corr)93.6 336 Q
(esponds to 0 and a value of 10.0 corr)-.18 E
(esponds to 4096 in the upper 12 bits of the)-.18 E
(16-bit "send_rate" field .)93.6 348 Q(Thus:)5 E F1
(send_rate = \(\(\(int\)\(M * 4096.0 / 10.0 + 0.5\)\) << 4\) | E;)130.8
372 Q F0(For example, to r)93.6 396 Q(epr)-.18 E
(esent a transmission rate of 256kbps \(3.2e+04 bytes per second\), the)
-.18 E(lower 4 bits of the 16-bit field contain a value of 0x04 to r)
93.6 408 Q(epr)-.18 E(esent the exponent \(E\) while the)-.18 E
(upper 12 bits contain a value of 0x51f \(M\) as determined fr)93.6 420
Q(om the equation given above:)-.18 E F1
(send_rate = \(\(\(int\)\(\(3.2 * 4096.0 / 10.0\) + 0.5\)\) << 4\) | 4;)
93.6 444 Q 6(=\()153.6 468 S(0x51f << 4\) | 0x4)-6 E 6(=0)153.6 492 S
(x51f4)-6 E F0 1.84 -.92(To d)93.6 516 T
(ecode the "send_rate" field, the following equation can be used:).92 E
F1(value = \(send_rate >> 4\) * \(10/4096\) * power\(10, \(send_rate & \
x000f\)\))93.6 540 Q F0
(Note the maximum transmission rate that can be r)93.6 564 Q(epr)-.18 E
(esented by this scheme is)-.18 E(appr)93.6 576 Q
(oximately 9.99e+15 bytes per second.)-.18 E(When this extension is pr)
93.6 600 Q
(esent, a "cc_node_list" may be attached as the payload of the)-.18 E F1
(NORM_CMD\(CC\))93.6 612 Q F0 2.5(message. The)2.5 F(pr)2.5 E
(esence of this header extension also implies that NORM)-.18 E -.18(re)
93.6 624 S(ceivers should r).18 E(espond accor)-.18 E(ding to the pr)
-.18 E(ocedur)-.18 E(es described in Section 5.5.2.)-.18 E(The)5 E
("cc_node_list" consists of a list of)93.6 636 Q F2(NormNodeIds)2.5 E F0
(and their associated congestion contr)2.5 E(ol status.)-.18 E
(This includes the curr)93.6 648 Q(ent limiting r)-.18 E
(eceiver \(CLR\) node, any potential limiting r)-.18 E(eceiver \(PLR\))
-.18 E(nodes that have been identified, and some number of r)93.6 660 Q
(eceivers for which congestion contr)-.18 E(ol)-.18 E
(status is being pr)93.6 672 Q(ovided, most notably including the r)-.18
E(eceivers' curr)-.18 E(ent R)-.18 E(TT measur)-.37 E(ement.)-.18 E
(The maximum length of the "cc_node_list" pr)93.6 684 Q
(ovides for at least the CLR and one other)-.18 E -.18(re)93.6 696 S
(ceiver).18 E 2.5(,b)-.74 G(ut may be configurable for mor)-2.5 E 2.5
(et)-.18 G(imely feedback to the gr)-2.5 E 2.5(oup. The)-.18 F
(list length can)2.5 E(be inferr)93.6 708 Q(ed fr)-.18 E
(om the length of the)-.18 E F1(NORM_CMD\(CC\))2.5 E F0(message.)2.5 E
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(Each item in the "cc_node_list" is in the following format:)93.6 120 Q
/F1 10/Courier@0 SF 114(0123)99.6 144 S 6
(01234567890123456789012345678901)99.6 156 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 156(|c)93.6 180 S 156(c_node_id |)-156 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 24(|c)93.6 204 S 12(c_flags |)-24 F 18(cc_rtt |)30 F 66(cc_rate |)
72 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
93.6 216 Q/F2 10/Palatino-Italic@0 SF(Congestion Contr)212.085 240 Q
(ol Node List Item Format)-.18 E F0(The "cc_node_id" is the)93.6 264 Q
F2(NormNodeId)2.5 E F0(of the r)2.5 E(eceiver which the item r)-.18 E
(epr)-.18 E(esents.)-.18 E
(The "cc_flags" field contains flags indicating the congestion contr)
93.6 288 Q(ol status of the indicated)-.18 E -.18(re)93.6 300 S(ceiver)
.18 E 5(.T)-.74 G(he following flags ar)-5 E 2.5(ed)-.18 G(efined:)-2.5
E .4 LW 533.03 322.5 72 322.5 DL 56.985(Flag V)121.485 332 R 138.24
(alue Purpose)-.92 F 533.03 336.5 72 336.5 DL F1(NORM_FLAG_CC_CLR)77 346
Q F0(0x01)29.435 E(Receiver is the curr)240.03 346 Q(ent limiting r)-.18
E(eceiver \(CLR\).)-.18 E 533.03 350.5 72 350.5 DL F1(NORM_FLAG_CC_PLR)
77 360 Q F0(0x02)29.435 E(Receiver is a potential limiting r)240.03 360
Q(eceiver \(PLR\).)-.18 E 533.03 364.5 72 364.5 DL F1(NORM_FLAG_CC_RTT)
77 374 Q F0(0x04)29.435 E(Receiver has measur)240.03 374 Q(ed R)-.18 E
(TT with r)-.37 E(espect to sender)-.18 E(.)-.74 E 533.03 378.5 72 378.5
DL F1(NORM_FLAG_CC_START)77 388 Q F0(0x08)17.435 E(Sender/r)240.03 388 Q
(eceiver is in "slow start" phase of congestion contr)-.18 E(ol)-.18 E
(operation \(i.e., The r)240.03 400 Q
(eceiver has not yet detected any packet loss)-.18 E
(and the "cc_rate" field is the r)240.03 412 Q -1.76(eceiver 's)-.18 F
(actual measur)2.5 E(ed r)-.18 E(eceive)-.18 E(rate\).)240.03 424 Q
533.03 428.5 72 428.5 DL F1(NORM_FLAG_CC_LEAVE)77 438 Q F0(0x10)17.435 E
(Receiver is imminently leaving the session and its feedback)240.03 438
Q(should not be consider)240.03 450 Q(ed in congestion contr)-.18 E
(ol operation.)-.18 E 533.03 454.5 72 454.5 DL 533.03 322.5 533.03 454.5
DL 72 322.5 72 454.5 DL 232.53 322.5 232.53 454.5 DL 192.5 322.5 192.5
454.5 DL(The "cc_rtt" contains a quantized r)93.6 480 Q(epr)-.18 E
(esentation of the R)-.18 E(TT as measur)-.37 E(ed by the sender with)
-.18 E -.18(re)93.6 492 S(spect to the indicated r).18 E(eceiver)-.18 E
5(.T)-.74 G(his field is valid only if the)-5 E F1(NORM_FLAG_CC_RTT)2.5
E F0(flag is)2.5 E(set in the "cc_flags" field.)93.6 504 Q
(This one byte field is a quantized r)5 E(epr)-.18 E
(esentation of the R)-.18 E(TT using)-.37 E
(the algorithm described in the NORM Building Block document [3].)93.6
516 Q(The "cc_rate" field)5 E(contains a r)93.6 528 Q(epr)-.18 E
(esentation of the r)-.18 E -1.76(eceiver 's)-.18 F(curr)2.5 E
(ent calculated \(during steady-state congestion)-.18 E(contr)93.6 540 Q
(ol operation\) or twice its measur)-.18 E
(ed \(during the "slow start" phase\) congestion contr)-.18 E(ol)-.18 E
2.5(rate. This)93.6 552 R(field is encoded and decoded using the same t\
echnique as described for the)2.5 E F1(NORM_CMD\(CC\))93.6 564 Q F0
("send_rate" field.)2.5 E/F3 10/Palatino-Bold@0 SF 2.5
(4.2.3.5. NORM_CMD\(REP)72 600 R(AIR_ADV\) Message)-.74 E F0(The)93.6
615.6 Q F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(message is used by the sender to "advertise" its aggr)2.5 E(egated)-.18
E -.18(re)93.6 627.6 S(pair state fr).18 E(om)-.18 E F1(NORM_NACK)2.5 E
F0(messages accumulated during a r)2.5 E(epair cycle and/or)-.18 E
(congestion contr)93.6 639.6 Q(ol feedback r)-.18 E 2.5(eceived. This)
-.18 F(message is sent only when the sender has)2.5 E -.18(re)93.6 651.6
S(ceived).18 E F1(NORM_NACK)2.5 E F0(and/or)2.5 E F1(NORM_ACK\(CC\))2.5
E F0(\(when congestion contr)2.5 E(ol is enabled\))-.18 E
(messages via unicast transmission instead of multicast.)93.6 663.6 Q
(By "echoing" this information to the)5 E -.18(re)93.6 675.6 S
(ceiver set, suppr).18 E(ession of feedback can be achieved even when r)
-.18 E(eceivers ar)-.18 E 2.5(eu)-.18 G(nicasting)-2.5 E
(that feedback instead of multicasting it among the gr)93.6 687.6 Q
(oup [17].)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
(es: 31 December 2007)-.18 E([Page 32])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q(|version| type=3|)93.6 156 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 162(|s)93.6 180 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 60(|i)93.6 204 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 12(|f)93.6 228 S(lavor = 5)-12 E 30(|f)18 G 24(lags |)-30 F 60
(reserved |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
240 Q 90(|h)93.6 252 S(eader extensions \(if applicable\))-90 E(|)90 E
180(|.)93.6 264 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
276 Q 138(|r)93.6 288 S 126(epair_adv_payload |)-138 F 180(|.)93.6 300 S
174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
312 Q/F2 10/Palatino-Italic@0 SF(NORM_CMD\(REP)199.73 336 Q
(AIR_ADV\) Message Format)-1.29 E F0(The "instance_id", "grtt", "backof)
93.6 360 Q
(f", "gsize", and "flavor" fields serve the same purpose as in)-.18 E
(other)93.6 372 Q F1(NORM_CMD)2.5 E F0 2.5(messages. The)2.5 F
(value of the "hdr_len" field when no extensions ar)2.5 E 2.5(ep)-.18 G
-.18(re)-2.5 G(sent).18 E(is 4.)93.6 384 Q(The "flags" field pr)93.6 408
Q(ovide information on the)-.18 E F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0 2.5
(content. Ther)2.5 F 2.5(ei)-.18 G(s)-2.5 E(curr)93.6 420 Q(ently one)
-.18 E F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0(flag defined:)2.5 E F1
(NORM_REPAIR_ADV_FLAG_LIMIT = 0x01)199.8 444 Q F0
(This flag is set by the sender when it is unable to fit its full curr)
93.6 468 Q(ent r)-.18 E(epair state into a single)-.18 E F2
(NormSegmentSize)93.6 480 Q F0 5(.I)C 2.5(ft)-5 G(his flag is set, r)
-2.5 E(eceivers should limit their NACK r)-.18 E(esponse to)-.18 E
(generating NACK content only up thr)93.6 492 Q(ough the maximum or)-.18
E(dinal transmission position)-.18 E F2(\(objectId::fecPayloadId\))93.6
504 Q F0(included in the "r)2.5 E(epair_adv_content".)-.18 E
(When congestion contr)93.6 528 Q
(ol operation is enabled, a header extension may be applied to the)-.18
E F1(NORM_CMD\(REPAIR_ADV\))93.6 540 Q F0 -.18(re)2.5 G(pr).18 E
(esenting the most limiting \(in terms of congestion contr)-.18 E(ol)
-.18 E(feedback suppr)93.6 552 Q(ession\) congestion contr)-.18 E(ol r)
-.18 E 2.5(esponse. This)-.18 F(allows the)2.5 E F1
(NORM_CMD\(REPAIR_ADV\))93.6 564 Q F0(message to suppr)2.5 E(ess r)-.18
E(eceiver congestion contr)-.18 E(ol r)-.18 E(esponses as)-.18 E
(well as NACK feedback messages.)93.6 576 Q
(The field is defined as a header extension so that)5 E
(alternative congestion contr)93.6 588 Q
(ol schemes may be used with NORM without r)-.18 E(evision to this)-.18
E 2.5(document. A)93.6 600 R
(NORM-CC Feedback Header Extension \(EXT_CC\) is defined to encapsulate)
2.5 E(congestion contr)93.6 612 Q(ol feedback within)-.18 E F1
(NORM_NACK)2.5 E F0(,)A F1(NORM_ACK)2.5 E F0 2.5(,a)C(nd)-2.5 E F1
(NORM_CMD\(REPAIR_ADV\))2.5 E F0 2.5(messages. If)93.6 624 R
(another congestion contr)2.5 E
(ol technique \(e.g., Pragmatic General Multicast)-.18 E
(Congestion Contr)93.6 636 Q(ol \(PGMCC\) [26]\) is used within a NORM \
implementation, an additional)-.18 E(header extension MA)93.6 648 Q 2.5
(Yn)-1.11 G(eed to be defined encapsulate any r)-2.5 E(equir)-.18 E
(ed feedback content.)-.18 E(The)5 E
(NORM-CC Feedback Header Extension format is:)93.6 660 Q
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q 30(|h)93.6 156 S(et = 3)-30 E 24(|h)18 G(el = 3)-24 E 60(|c)24 G
54(c_sequence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 24(|c)93.6 180 S 12(c_flags |)-24 F 18(cc_rtt |)30 F 66(cc_loss |)
72 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
93.6 192 Q 72(|c)93.6 204 S 66(c_rate |)-72 F 54(cc_reserved |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q/F2 10/Palatino-Italic@0 SF
(NORM-CC Feedback Header Extension \(EXT_CC\) Format)178.755 240 Q F0
(The "cc_sequence" field contains the curr)93.6 264 Q(ent gr)-.18 E
(eatest "cc_sequence" value r)-.18 E(eceivers have)-.18 E -.18(re)93.6
276 S(ceived in).18 E F1(NORM_CMD\(CC\))2.5 E F0(messages fr)2.5 E
(om the sender)-.18 E 5(.T)-.74 G(his information assists the sender)-5
E(in congestion contr)93.6 288 Q(ol operation by pr)-.18 E
(oviding an indicator of how curr)-.18 E(ent \("fr)-.18 E(esh"\) the)
-.18 E -.18(re)93.6 300 S -1.76(ceiver 's).18 F -.18(ro)2.5 G
(und-trip measur).18 E(ement r)-.18 E(efer)-.18 E
(ence time is and whether the r)-.18 E(eceiver has been)-.18 E
(successfully r)93.6 312 Q(eceiving r)-.18 E(ecent congestion contr)-.18
E(ol pr)-.18 E 2.5(obes. For)-.18 F(example, if it is appar)2.5 E
(ent the)-.18 E -.18(re)93.6 324 S(ceiver has not been r).18 E
(eceiving r)-.18 E(ecent congestion contr)-.18 E(ol pr)-.18 E
(obes \(and thus possibly other)-.18 E(messages fr)93.6 336 Q(om the se\
nder\), the sender may choose to take congestion avoidance measur)-.18 E
(es.)-.18 E(For)93.6 348 Q F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(messages, the sender SHALL set the "cc_sequence" field)2.5 E
(value to the value set in the last)93.6 360 Q F1(NORM_CMD\(CC\))2.5 E
F0(message sent.)2.5 E(The "cc_flags" field contains bits r)93.6 384 Q
(epr)-.18 E(esenting the r)-.18 E -1.76(eceiver 's)-.18 F(state with r)
2.5 E(espect to congestion)-.18 E(contr)93.6 396 Q(ol operation.)-.18 E
(The possible values for the "cc_flags" field ar)5 E 2.5(et)-.18 G
(hose specified for the)-2.5 E F1(NORM_CMD\(CC\))93.6 408 Q F0
(message node list item flags.)2.5 E(These fields ar)5 E 2.5(eu)-.18 G
(sed by r)-2.5 E(eceivers in)-.18 E(contr)93.6 420 Q(olling \(suppr)-.18
E(essing as necessary\) their congestion contr)-.18 E(ol feedback.)-.18
E(For)5 E F1(NORM_CMD\(REPAIR_ADV\))93.6 432 Q F0
(messages, the NORM_FLAG_CC_R)2.5 E(TT should be set)-.37 E F2(only)2.5
E F0(when)2.5 E F2(all)93.6 444 Q F0(feedback messages r)2.5 E
(eceived by the sender have the flag set.)-.18 E(Similarly)5 E 2.5(,t)
-1.11 G(he)-2.5 E
(NORM_FLAG_CC_CLR or NORM_FLAG_CC_PLR should be set only when)93.6 456 Q
F2(no)2.5 E F0(feedback)2.5 E(has been r)93.6 468 Q(eceived fr)-.18 E
(om non-CLR or non-PLR r)-.18 E 2.5(eceivers. And)-.18 F
(the NORM_FLAG_CC_LEA)2.5 E(VE)-1.11 E
(should be set only when all feedback messages the sender has r)93.6 480
Q(eceived have this flag set.)-.18 E
(These heuristics for setting the flags in)93.6 492 Q F1
(NORM_CMD\(REPAIR_ADV\))2.5 E F0(ensur)2.5 E 2.5(et)-.18 G(he most ef)
-2.5 E(fective)-.18 E(suppr)93.6 504 Q(ession of r)-.18 E(eceivers pr)
-.18 E(oviding unicast feedback messages.)-.18 E
(The "cc_rtt" field SHALL be set to a default maximum value and the)93.6
528 Q F1(NORM_FLAG_CC_RTT)2.5 E F0(flag SHALL be clear)93.6 540 Q
(ed when no r)-.18 E(eceiver has yet r)-.18 E(eceived R)-.18 E
(TT measur)-.37 E(ement information.)-.18 E(When a r)93.6 552 Q
(eceiver has r)-.18 E(eceived R)-.18 E(TT measur)-.37 E
(ement information, it shall set the "cc_rtt" value)-.18 E(accor)93.6
564 Q(dingly and set the)-.18 E F1(NORM_FLAG_CC_RTT)2.5 E F0
(flag in the "cc_flags" field.)2.5 E(For)5 E F1(NORM_CMD\(REPAIR_ADV\))
93.6 576 Q F0
(messages, the sender SHALL set the "cc_rtt" field value to the)2.5 E
(lar)93.6 588 Q(gest non-CLR/non-PLR R)-.18 E(TT it has measur)-.37 E
(ed fr)-.18 E(om r)-.18 E(eceivers for the curr)-.18 E(ent feedback)-.18
E -.18(ro)93.6 600 S(und.).18 E(The "cc_loss" field r)93.6 624 Q(epr)
-.18 E(esents the r)-.18 E -1.76(eceiver 's)-.18 F(curr)2.5 E
(ent packet loss fraction estimate for the)-.18 E(indicated sour)93.6
636 Q 2.5(ce. The)-.18 F(loss fraction is a value fr)2.5 E
(om 0.0 to 1.0 corr)-.18 E(esponding to a range of zer)-.18 E(o)-.18 E
(to 100 per)93.6 648 Q(cent packet loss.)-.18 E
(The 16-bit "cc_loss" value is calculated by the following formula:)5 E
F1("cc_loss" = decimal_loss_fraction * 65535.0)169.8 672 Q F0(For)93.6
696 Q F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(messages, the sender SHALL set the "cc_loss" field value to)2.5 E
(the lar)93.6 708 Q(gest non-CLR/non-PLR loss estimate it has r)-.18 E
(eceived fr)-.18 E(om r)-.18 E(eceivers for the curr)-.18 E(ent)-.18 E
(feedback r)93.6 720 Q(ound.)-.18 E(Adamson, et al.)72 768 Q(Expir)
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(The "cc_rate" field r)93.6 120
Q(epr)-.18 E(esents the r)-.18 E(eceivers curr)-.18 E
(ent local congestion contr)-.18 E(ol rate.)-.18 E(During)5 E
("slow start", when the r)93.6 132 Q(eceiver has detected no loss, this\
 value is set to twice the actual rate it)-.18 E(has measur)93.6 144 Q
(ed fr)-.18 E(om the corr)-.18 E
(esponding sender and the NORM_FLAG_CC_ST)-.18 E(AR)-.74 E 2.5(Ti)-.37 G
2.5(ss)-2.5 G(et in the)-2.5 E("cc_flags' field.)93.6 156 Q
(Otherwise, the r)5 E(eceiver calculates a congestion contr)-.18 E
(ol rate based on its loss)-.18 E(measur)93.6 168 Q(ement and R)-.18 E
(TT measur)-.37 E
(ement information \(even if default\) for the "cc_rate" field.)-.18 E
(For)5 E/F1 10/Courier@0 SF(NORM_CMD\(REPAIR_ADV\))93.6 180 Q F0
(messages, the sender SHALL set the "cc_loss" field value to the)2.5 E
(lowest non-CLR/non-PLR "cc_rate" r)93.6 192 Q(eport it has r)-.18 E
(eceived fr)-.18 E(om r)-.18 E(eceivers for the curr)-.18 E(ent)-.18 E
(feedback r)93.6 204 Q(ound.)-.18 E(The "cc_r)93.6 228 Q
(eserved" field is r)-.18 E(eserved for futur)-.18 E 2.5(eN)-.18 G
(ORM pr)-2.5 E(otocol use.)-.18 E(Curr)5 E(ently)-.18 E 2.5(,s)-1.11 G
(enders)-2.5 E(SHALL set this field to ZERO, and r)93.6 240 Q
(eceivers SHALL ignor)-.18 E 2.5(et)-.18 G(he content of this field.)
-2.5 E(The "r)93.6 264 Q(epair_adv_payload" is in exactly the same form\
 as the "nack_content" of)-.18 E F1(NORM_NACK)2.5 E F0
(messages and can be pr)93.6 276 Q(ocessed by r)-.18 E
(eceivers for suppr)-.18 E(ession purposes in the same manner)-.18 E(,)
-.74 E(with the exception of the condition when the NORM_REP)93.6 288 Q
(AIR_ADV_FLAG_LIMIT is set.)-.92 E/F2 10/Palatino-Bold@0 SF 2.5
(4.2.3.6. NORM_CMD\(ACK_REQ\))72 324 R(Message)2.5 E F0(The)93.6 339.6 Q
F1(NORM_CMD\(ACK_REQ\))2.5 E F0(message is used by the sender to r)2.5 E
(equest acknowledgment fr)-.18 E(om)-.18 E 2.5(as)93.6 351.6 S
(pecified list of r)-2.5 E 2.5(eceivers. This)-.18 F
(message is used in pr)2.5 E(oviding a lightweight positive)-.18 E
(acknowledgment mechanism that is OPTIONAL for use by the r)93.6 363.6 Q
(eliable multicast)-.18 E 2.5(application. A)93.6 375.6 R
(range of acknowledgment r)2.5 E(equest types is pr)-.18 E
(ovided for use at the)-.18 E(application's discr)93.6 387.6 Q 2.5
(etion. Pr)-.18 F
(ovision for application-defined, positively-acknowledged)-.18 E(comman\
ds allows the application to automatically take advantage of transmissi\
on and)93.6 399.6 Q -.18(ro)93.6 411.6 S
(und-trip timing information available to the NORM pr).18 E 2.5
(otocol. The)-.18 F(details of the NORM)2.5 E
(positive acknowledgment pr)93.6 423.6 Q
(ocess including transmission of the)-.18 E F1(NORM_CMD\(ACK_REQ\))2.5 E
F0(messages and the r)93.6 435.6 Q(eceiver r)-.18 E(esponse \()-.18 E F1
(NORM_ACK)A F0 2.5(\)a)C .36 -.18(re d)-2.5 H
(escribed in Section 5.5.3.).18 E(The format)5 E(of the)93.6 447.6 Q F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(message is:)2.5 E F1 114(0123)99.6 471.6 S
6(01234567890123456789012345678901)99.6 483.6 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
495.6 Q(|version| type=3|)93.6 507.6 Q 18(hdr_len |)24 F 72(sequence |)
60 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
93.6 519.6 Q 162(|s)93.6 531.6 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
543.6 Q 60(|i)93.6 555.6 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
567.6 Q 12(|f)93.6 579.6 S(lavor = 6)-12 E 24(|r)18 G 12(eserved |)-24 F
12(ack_type |)24 F 24(ack_id |)24 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
591.6 Q 138(|a)93.6 603.6 S 138(cking_node_list |)-138 F 180(|.)93.6
615.6 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
627.6 Q/F3 10/Palatino-Italic@0 SF(NORM_CMD\(ACK_REQ\) Message Format)
207.69 651.6 Q F0(The NORM common message header and standar)93.6 675.6
Q(d)-.18 E F1(NORM_CMD)2.5 E F0(fields serve their usual)2.5 E 2.5
(purposes. The)93.6 687.6 R(value of the "hdr_len" field for)2.5 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(messages with no)2.5 E
(header extension pr)93.6 699.6 Q(esent is 4.)-.18 E(Adamson, et al.)72
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(The "ack_type" field indicates the type of acknowledgment being r)93.6
120 Q(equested and thus implies)-.18 E -.08(ru)93.6 132 S
(les for how the r).08 E(eceiver will tr)-.18 E(eat this r)-.18 E 2.5
(equest. The)-.18 F(following "ack_type" values ar)2.5 E(e)-.18 E
(defined and ar)93.6 144 Q 2.5(ea)-.18 G(lso used in)-2.5 E/F1 10
/Courier@0 SF(NORM_ACK)2.5 E F0(messages described later:)2.5 E .4 LW
499.165 166.5 76.835 166.5 DL(ACK T)118.725 176 Q 51.04(ype V)-.9 F
109.14(alue Purpose)-.92 F 499.165 180.5 76.835 180.5 DL F1(NORM_ACK_CC)
81.835 190 Q F0(1)92.33 E(Used to identify)260.165 190 Q F1(NORM_ACK)2.5
E F0(messages sent in)2.5 E -.18(re)260.165 202 S(sponse to).18 E F1
(NORM_CMD\(CC\))2.5 E F0(messages.)2.5 E 499.165 206.5 76.835 206.5 DL
F1(NORM_ACK_FLUSH)81.835 216 Q F0(2)74.33 E(Used to identify)260.165 216
Q F1(NORM_ACK)2.5 E F0(messages sent in)2.5 E -.18(re)260.165 228 S
(sponse to).18 E F1(NORM_CMD\(FLUSH\))2.5 E F0(messages.)2.5 E 499.165
232.5 76.835 232.5 DL F1(NORM_ACK_RESERVED)81.835 242 Q F0(3-15)43 E
(Reserved for possible futur)260.165 242 Q 2.5(eN)-.18 G(ORM pr)-2.5 E
(otocol use.)-.18 E 499.165 246.5 76.835 246.5 DL F1
(NORM_ACK_APPLICATION)81.835 256 Q F0(16-255)15 E
(Used at application's discr)260.165 256 Q(etion.)-.18 E 499.165 260.5
76.835 260.5 DL 499.165 166.5 499.165 260.5 DL 76.835 166.5 76.835 260.5
DL 252.665 166.5 252.665 260.5 DL 209.335 166.5 209.335 260.5 DL(The)
93.6 286 Q F1(NORM_ACK_CC)2.5 E F0(value is pr)2.5 E
(ovided for use only in)-.18 E F1(NORM_ACKs)2.5 E F0(generated in r)2.5
E(esponse to)-.18 E(the)93.6 298 Q F1(NORM_CMD\(CC\))2.5 E F0
(messages used in congestion contr)2.5 E(ol operation.)-.18 E(Similarly)
5 E 2.5(,t)-1.11 G(he)-2.5 E F1(NORM_ACK_FLUSH)93.6 310 Q F0(is pr)2.5 E
(ovided for use only in)-.18 E F1(NORM_ACKs)2.5 E F0(generated in r)2.5
E(esponse to)-.18 E(applicable)93.6 322 Q F1(NORM_CMD\(FLUSH\))2.5 E F0
(messages.)2.5 E F1(NORM_CMD)5 E F0
(\(ACK_REQ\) messages with "ack_type")A(of)93.6 334 Q F1(NORM_ACK_CC)2.5
E F0(or)2.5 E F1(NORM_ACK_FLUSH)2.5 E F0
(SHALL NOT be generated by the sender)2.5 E(.)-.74 E(The)93.6 358 Q F1
(NORM_ACK_RESERVED)2.5 E F0(range of "ack_type" values is pr)2.5 E
(ovided for possible futur)-.18 E(e)-.18 E(NORM pr)93.6 370 Q
(otocol use.)-.18 E(The)93.6 394 Q F1(NORM_ACK_APPLICATION)2.5 E F0
(range of "ack_type" values is pr)2.5 E(ovided so that NORM)-.18 E(appl\
ications may implement application-defined, positively-acknowledged com\
mands that)93.6 406 Q(ar)93.6 418 Q 2.5(ea)-.18 G
(ble to leverage internal transmission and r)-2.5 E
(ound-trip timing information available to the)-.18 E(NORM pr)93.6 430 Q
(otocol implementation.)-.18 E(The "ack_id" pr)93.6 454 Q
(ovides a sequenced identifier for the given)-.18 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(message.)2.5 E(This "ack_id" is r)93.6 466
Q(eturned in)-.18 E F1(NORM_ACK)2.5 E F0(messages generated by the r)2.5
E(eceivers so that the)-.18 E(sender may associate the r)93.6 478 Q
(esponse with its corr)-.18 E(esponding r)-.18 E(equest.)-.18 E(The "r)
93.6 502 Q(eserved" field is r)-.18 E(eserved for possible futur)-.18 E
2.5(ep)-.18 G -.18(ro)-2.5 G(tocol use and SHALL be set to ZERO).18 E
(by senders and ignor)93.6 514 Q(ed by r)-.18 E(eceivers.)-.18 E
(The "acking_node_list" field contains the)93.6 538 Q/F2 10
/Palatino-Italic@0 SF(NormNodeIds)2.5 E F0(of the curr)2.5 E(ent NORM r)
-.18 E(eceivers that)-.18 E(ar)93.6 550 Q 2.5(ed)-.18 G(esir)-2.5 E
(ed to pr)-.18 E(ovide positive acknowledge \()-.18 E F1(NORM_ACK)A F0
2.5(\)t)C 2.5(ot)-2.5 G(his r)-2.5 E 2.5(equest. The)-.18 F(packet)2.5 E
(payload length implies the length of the "acking_node_list" and its le\
ngth is limited to the)93.6 562 Q(sender)93.6 574 Q F2(NormSegmentSize)
2.5 E F0 5(.T)C(he individual)-5 E F2(NormNodeId)2.5 E F0(items ar)2.5 E
2.5(el)-.18 G(isted in network \(Big)-2.5 E(Endian\) byte or)93.6 586 Q
(der)-.18 E 5(.I)-.74 G 2.5(far)-5 G -1.76(eceiver 's)-2.68 F F2
(NormNodeId)2.5 E F0(is included in the "acking_node_list", it)2.5 E
(SHALL schedule transmission of a)93.6 598 Q F1(NORM_ACK)2.5 E F0
(message as described in Section 5.5.3.)2.5 E/F3 10/Palatino-Bold@0 SF
2.5(4.2.3.7. NORM_CMD\(APPLICA)72 622 R(TION\) Message)-.92 E F0
(This command allows the NORM application to r)93.6 637.6 Q
(obustly transmit application-defined)-.18 E 2.5(commands. The)93.6
649.6 R(command message pr)2.5 E
(eempts any ongoing data transmission and is)-.18 E -.18(re)93.6 661.6 S
(peated up to).18 E F1(NORM_ROBUST_FACTOR)2.5 E F0
(times at a rate of once per)2.5 E F1(2*GRTT)2.5 E F0 5(.T)C
(his rate of)-5 E -.18(re)93.6 673.6 S
(petition allows the application to observe any r).18 E
(esponse \(if that is the application's purpose)-.18 E
(for the command\) befor)93.6 685.6 Q 2.5(ei)-.18 G 2.5(ti)-2.5 G 2.5
(sr)-2.5 G 2.5(epeated. Possible)-2.68 F -.18(re)2.5 G
(sponses may include initiation of data).18 E(transmission, other)93.6
697.6 Q F1(NORM_CMD\(APPLICATION\))2.5 E F0
(messages, or even application-defined,)2.5 E
(positively-acknowledge commands fr)93.6 709.6 Q(om other)-.18 E F2
(NormSession)2.5 E F0 2.5(participants. The)2.5 F(transmission)2.5 E
(of these commands will pr)93.6 721.6 Q
(eempt data transmission when they ar)-.18 E 2.5(es)-.18 G
(cheduled and may be)-2.5 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(multiplexed with ongoing data transmission.)93.6 120 Q(This type of r)5
E(obustly transmitted command)-.18 E
(allows NORM applications to define a complete set of session contr)93.6
132 Q(ol mechanisms with less)-.18 E
(state than the transfer of FEC encoded r)93.6 144 Q(eliable content r)
-.18 E(equir)-.18 E(es while taking advantage of)-.18 E
(NORM transmission and r)93.6 156 Q(ound-trip timing information.)-.18 E
/F1 10/Courier@0 SF 114(0123)99.6 180 S 6
(01234567890123456789012345678901)99.6 192 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
204 Q(|version| type=3|)93.6 216 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
228 Q 162(|s)93.6 240 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
252 Q 60(|i)93.6 264 S 54(nstance_id |)-60 F 30(grtt |backoff|)30 F
(gsize |)6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
276 Q 12(|f)93.6 288 S(lavor = 7)-12 E 120(|r)18 G 108(eserved |)-120 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
300 Q 114(|A)93.6 312 S(pplication-Defined Content)-114 E(|)102 E 180
(|.)93.6 324 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
336 Q/F2 10/Palatino-Italic@0 SF(NORM_CMD\(APPLICA)197.415 360 Q
(TION\) Message Format)-.55 E F0(The NORM common message header and)93.6
384 Q F1(NORM_CMD)2.5 E F0(fields ar)2.5 E 2.5(ei)-.18 G(nterpr)-2.5 E
(eted as pr)-.18 E(eviously)-.18 E 2.5(described. The)93.6 396 R
(value of the)2.5 E F1(NORM_CMD\(APPLICATION\))2.5 E F0
("hdr_len" field when no header)2.5 E(extensions ar)93.6 408 Q 2.5(ep)
-.18 G -.18(re)-2.5 G(sent is 4.).18 E
(The "Application-Defined Content" ar)93.6 432 Q
(ea contains information in a format at the discr)-.18 E(etion of)-.18 E
(the application.)93.6 444 Q
(The size of this payload SHALL be limited to a maximum of the sender)5
E('s).74 E F2(NormSegmentSize)93.6 456 Q F0(setting.)2.5 E/F3 10
/Palatino-Bold@0 SF(4.3.)72 480 Q/F4 12/Palatino-Bold@0 SF
(Receiver Messages)5 E F0
(The NORM message types generated by participating r)93.6 495.6 Q
(eceivers consist of)-.18 E F1(NORM_NACK)2.5 E F0(and)2.5 E F1(NORM_ACK)
93.6 507.6 Q F0(message types.)2.5 E F1(NORM_NACK)5 E F0(messages ar)2.5
E 2.5(es)-.18 G(ent to r)-2.5 E(equest r)-.18 E(epair of missing data)
-.18 E(content fr)93.6 519.6 Q(om sender transmission and)-.18 E F1
(NORM_ACK)2.5 E F0(messages ar)2.5 E 2.5(eg)-.18 G(enerated in r)-2.5 E
(esponse to)-.18 E(certain sender commands including)93.6 531.6 Q F1
(NORM_CMD\(CC\))2.5 E F0(and)2.5 E F1(NORM_CMD\(ACK_REQ\))2.5 E F0(.)A
F3 2.5(4.3.1. NORM_NACK)72 555.6 R(Message)2.5 E F0
(The principal purpose of)93.6 571.2 Q F1(NORM_NACK)2.5 E F0
(messages is for r)2.5 E(eceivers to r)-.18 E(equest r)-.18 E
(epair of sender)-.18 E(content via selective, negative acknowledgment \
upon detection of incomplete data.)93.6 583.2 Q F1(NORM_NACK)93.6 595.2
Q F0(messages will be transmitted accor)2.5 E(ding to the r)-.18 E
(ules of)-.08 E F1(NORM_NACK)2.5 E F0(generation)2.5 E(and suppr)93.6
607.2 Q(ession described in Section 5.3.)-.18 E F1(NORM_NACK)5 E F0
(messages also contain additional)2.5 E(fields to pr)93.6 619.2 Q
(ovide feedback to the sender\(s\) for purposes of r)-.18 E
(ound-trip timing collection and)-.18 E(congestion contr)93.6 631.2 Q
(ol.)-.18 E(The payload of)93.6 655.2 Q F1(NORM_NACK)2.5 E F0
(messages contains one or mor)2.5 E 2.5(er)-.18 G(epair r)-2.68 E
(equests for dif)-.18 E(fer)-.18 E(ent)-.18 E
(objects or portions of those objects.)93.6 667.2 Q(The)5 E F1
(NORM_NACK)2.5 E F0(message format is as follows:)2.5 E(Adamson, et al.)
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q(|version| type=4|)93.6 156 Q 18(hdr_len |)24 F 60(sequence |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 162(|s)93.6 180 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 162(|s)93.6 204 S 156(erver_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 66(|i)93.6 228 S 48(nstance_id |)-66 F 60(reserved |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
240 Q 138(|g)93.6 252 S 132(rtt_response_sec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
264 Q 138(|g)93.6 276 S 126(rtt_response_usec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
288 Q 90(|h)93.6 300 S(eader extensions \(if applicable\))-90 E(|)90 E
180(|.)93.6 312 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
324 Q 156(|n)93.6 336 S 144(ack_payload |)-156 F 180(|.)93.6 348 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
360 Q/F2 10/Palatino-Italic@0 SF(NORM_NACK Message Format)231.855 384 Q
F0(The NORM common message header fields serve their usual purposes.)
93.6 408 Q(The value of the)5 E("hdr_len" field for)93.6 420 Q F1
(NORM_NACK)2.5 E F0(messages without header extensions pr)2.5 E
(esent is 6.)-.18 E
(The "server_id" field identifies the NORM sender to which the)93.6 444
Q F1(NORM_NACK)2.5 E F0(message is)2.5 E(destined.)93.6 456 Q
(The "instance_id" field contains the curr)93.6 480 Q
(ent session identifier given by the sender identified)-.18 E
(by the "server_id" field in its sender messages.)93.6 492 Q
(The sender SHOULD ignor)5 E 2.5(ef)-.18 G(eedback)-2.5 E
(messages which contain an invalid "instance_id" value.)93.6 504 Q
(The "grtt_r)93.6 528 Q
(esponse" fields contain an adjusted version of the timestamp fr)-.18 E
(om the most)-.18 E -.18(re)93.6 540 S(cently r).18 E(eceived)-.18 E F1
(NORM_CMD\(CC\))2.5 E F0(message for the indicated NORM sender)2.5 E 5
(.T)-.74 G(he format of)-5 E(the "grtt_r)93.6 552 Q
(esponse" is the same as the "send_time" field of the)-.18 E F1
(NORM_CMD\(CC\))2.5 E F0 5(.T)C(he)-5 E("grtt_r)93.6 564 Q
(esponse" value is _r)-.18 E(elative_ to the "send_time" the sour)-.18 E
(ce pr)-.18 E(ovided with a)-.18 E(corr)93.6 576 Q(esponding)-.18 E F1
(NORM_CMD\(CC\))2.5 E F0 2.5(command. The)2.5 F -.18(re)2.5 G
(ceiver adjusts the sour).18 E(ce's)-.18 E F1(NORM_CMD\(CC\))93.6 588 Q
F0("send_time" timestamp by adding the time delta fr)2.5 E
(om when the r)-.18 E(eceiver)-.18 E -.18(re)93.6 600 S(ceived the).18 E
F1(NORM_CMD\(CC\))2.5 E F0(to when the)2.5 E F1(NORM_NACK)2.5 E F0
(is transmitted in r)2.5 E(esponse to calculate)-.18 E
(the value in the "grtt_r)93.6 612 Q(esponse" field.)-.18 E
(This is the "r)5 E(eceive_to_r)-.18 E(esponse_delta" value used in)-.18
E(the following formula:)93.6 624 Q F1
(grtt_response = NORM_CMD\(CC\) send_time + receive_to_response_delta)
100.8 648 Q F0(The r)93.6 672 Q(eceiver SHALL set the "grtt_r)-.18 E
(esponse" to a ZERO value, to indicate that it has not yet)-.18 E -.18
(re)93.6 684 S(ceived a).18 E F1(NORM_CMD\(CC\))2.5 E F0(message fr)2.5
E(om the indicated sender and that the sender should)-.18 E(ignor)93.6
696 Q 2.5(et)-.18 G(he "grtt_r)-2.5 E(esponse" in this message.)-.18 E(\
For NORM-CC operation, the NORM-CC Feedback Header Extension, as descri\
bed in the)93.6 720 Q(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF
(NORM_CMD\(REPAIR_ADV})93.6 120 Q F0(message description, is added to)
2.5 E F1(NORM_NACK)2.5 E F0(messages to)2.5 E(pr)93.6 132 Q
(ovide feedback on the r)-.18 E(eceivers curr)-.18 E(ent state with r)
-.18 E(espect to congestion contr)-.18 E(ol operation.)-.18 E
(Note that alternative header extensions for congestion contr)93.6 144 Q
(ol feedback may be defined for)-.18 E(alternative congestion contr)93.6
156 Q(ol schemes for NORM use in the futur)-.18 E(e.)-.18 E(The "r)93.6
180 Q(eserved" field is for potential futur)-.18 E 2.5(eN)-.18 G 2.5
(ORM use)-2.5 F(and SHALL be set to ZERO for this)2.5 E
(version of the pr)93.6 192 Q(otocol.)-.18 E(The "nack_content" of the)
93.6 216 Q F1(NORM_NACK)2.5 E F0(message specifies the r)2.5 E
(epair needs of the r)-.18 E(eceiver)-.18 E(with r)93.6 228 Q
(espect to the NORM sender indicated by the "server_id" field.)-.18 E
(The r)5 E(eceiver constr)-.18 E(ucts)-.08 E -.18(re)93.6 240 S(pair r)
.18 E(equests based on the)-.18 E F1(NORM_DATA)2.5 E F0(and/or)2.5 E F1
(NORM_INFO)2.5 E F0(segments it r)2.5 E(equir)-.18 E(es fr)-.18 E
(om the)-.18 E(sender in or)93.6 252 Q(der to complete r)-.18 E
(eliable r)-.18 E(eception up to the sender)-.18 E
('s transmission position at the).74 E(moment the r)93.6 264 Q
(eceiver initiates the NACK Pr)-.18 E(ocedur)-.18 E 2.5(ea)-.18 G 2.5
(sd)-2.5 G(escribed in Section 5.3.)-2.5 E 2.5(As)5 G(ingle)-2.5 E(NORM\
 Repair Request consists of a list of items, ranges, and/or FEC coding \
block erasur)93.6 276 Q(e)-.18 E(counts for needed)93.6 288 Q F1
(NORM_DATA)2.5 E F0(and/or)2.5 E F1(NORM_INFO)2.5 E F0 2.5
(content. Multiple)2.5 F -.18(re)2.5 G(pair r).18 E(equests may)-.18 E
(be concatenated within the "nack_payload" field of a)93.6 300 Q F1
(NORM_NACK)2.5 E F0 2.5(message. Note)2.5 F(that a)2.5 E(single NORM Re\
pair Request can possibly include multiple "items", "ranges", or)93.6
312 Q("erasur)93.6 324 Q 2.5(e_counts". In)-.18 F
(turn, the "nack_payload" field may contain multiple r)2.5 E(epair r)
-.18 E 2.5(equests. A)-.18 F
(single NORM Repair Request has the following format:)93.6 336 Q F1 114
(0123)99.6 360 S 6(01234567890123456789012345678901)99.6 372 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
384 Q 36(|f)93.6 396 S 24(orm | flags |)-36 F 66(length |)78 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
408 Q 132(|r)93.6 420 S 120(epair_request_items |)-132 F 174(|.)93.6 432
S 180(.. |)-174 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
444 Q/F2 10/Palatino-Italic@0 SF(NORM Repair Request Format)235.23 468 Q
F0(The "form" field indicates the type of r)93.6 492 Q(epair r)-.18 E
(equest items given in the)-.18 E("r)93.6 504 Q(epair_r)-.18 E
(equest_items" list.)-.18 E
(Possible values for the "form" field include:)5 E 54.6(Form V)256.085
534 R(alue)-.92 E F1(NORM_NACK_ITEMS)213.985 546 Q F0(1)43.015 E F1
(NORM_NACK_RANGES)213.985 558 Q F0(2)37.015 E F1(NORM_NACK_ERASURES)
213.985 570 Q F0(3)25.015 E 2.5(A")93.6 600 S(form" value of)-2.5 E F1
(NORM_NACK_ITEMS)2.5 E F0(indicates each r)2.5 E(epair r)-.18 E
(equest item in the)-.18 E("r)93.6 612 Q(epair_r)-.18 E
(equest_items" list is to be tr)-.18 E(eated as an individual r)-.18 E
2.5(equest. A)-.18 F(value of)2.5 E F1(NORM_NACK_RANGES)93.6 624 Q F0
(indicates that the "r)2.5 E(epair_r)-.18 E
(equest_items" list consists of)-.18 E F2(pairs)2.5 E F0(of r)2.5 E
(epair)-.18 E -.18(re)93.6 636 S(quest items that corr).18 E
(espond to inclusive ranges of r)-.18 E(epair needs.)-.18 E(And the)5 E
F1(NORM_NACK_ERASURES)93.6 648 Q F0("form" indicates that the r)2.5 E
(epair r)-.18 E(equest items ar)-.18 E 2.5(et)-.18 G 2.5(ob)-2.5 G 2.5
(et)-2.5 G -.18(re)-2.5 G(ated).18 E(individually and that the "encodin\
g_symbol_id" portion of the "fec_payload_id" field of the)93.6 660 Q
-.18(re)93.6 672 S(pair r).18 E
(equest item \(see below\) is to be interpr)-.18 E(eted as an "erasur)
-.18 E 2.5(ec)-.18 G(ount" for the FEC coding)-2.5 E
(block identified by the r)93.6 684 Q(epair r)-.18 E
(equest item's "sour)-.18 E(ce_block_number".)-.18 E(Adamson, et al.)72
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(The "flags" field is curr)93.6
120 Q(ently used to indicate the level of data content for which the r)
-.18 E(epair)-.18 E -.18(re)93.6 132 S
(quest items apply \(i.e., an individual segment, entir).18 E 2.5(eF)
-.18 G(EC coding block, or entir)-2.5 E 2.5(et)-.18 G(ransport)-2.5 E
2.5(object\). Possible)93.6 144 R(flag values include:)2.5 E .4 LW
527.03 166.5 72 166.5 DL 53.985(Flag V)118.485 176 R 138.24
(alue Purpose)-.92 F 527.03 180.5 72 180.5 DL/F1 10/Courier@0 SF
(NORM_NACK_SEGMENT)77 190 Q F0(0x01)17.435 E
(Indicates the listed segment\(s\) or range of segments ar)234.03 190 Q
2.5(er)-.18 G(equir)-2.68 E(ed)-.18 E(as r)234.03 202 Q(epair)-.18 E(.)
-.74 E 527.03 206.5 72 206.5 DL F1(NORM_NACK_BLOCK)77 216 Q F0(0x02)
29.435 E(Indicates the listed block\(s\) or range of blocks in entir)
234.03 216 Q(ety ar)-.18 E(e)-.18 E -.18(re)234.03 228 S(quir).18 E
(ed as r)-.18 E(epair)-.18 E(.)-.74 E 527.03 232.5 72 232.5 DL F1
(NORM_NACK_INFO)77 242 Q F0(0x04)35.435 E(Indicates that)234.03 242 Q F1
(NORM_INFO)2.5 E F0(is r)2.5 E(equir)-.18 E(ed as r)-.18 E
(epair for the listed)-.18 E(object\(s\).)234.03 254 Q 527.03 258.5 72
258.5 DL F1(NORM_NACK_OBJECT)77 268 Q F0(0x08)23.435 E
(Indicates the listed object\(s\) or range of objects in entir)234.03
268 Q(ety ar)-.18 E(e)-.18 E -.18(re)234.03 280 S(quir).18 E(ed as r)
-.18 E(epair)-.18 E(.)-.74 E 527.03 284.5 72 284.5 DL 527.03 166.5
527.03 284.5 DL 72 166.5 72 284.5 DL 226.53 166.5 226.53 284.5 DL 186.5
166.5 186.5 284.5 DL(When the)93.6 310 Q F1(NORM_NACK_SEGMENT)2.5 E F0
(flag is set, the "object_transport_id" and "fec_payload_id")2.5 E
(fields ar)93.6 322 Q 2.5(eu)-.18 G
(sed to determine which sets or ranges of individual)-2.5 E F1
(NORM_DATA)2.5 E F0(segments ar)2.5 E(e)-.18 E(needed to r)93.6 334 Q
(epair content at the r)-.18 E(eceiver)-.18 E 5(.W)-.74 G(hen the)-5 E
F1(NORM_NACK_BLOCK)2.5 E F0(flag is set, this)2.5 E(indicates the r)93.6
346 Q
(eceiver is completely missing the indicated coding block\(s\) and r)
-.18 E(equir)-.18 E(es)-.18 E(transmissions suf)93.6 358 Q(ficient to r)
-.18 E(epair the indicated block\(s\) in their entir)-.18 E(ety)-.18 E 5
(.W)-1.11 G(hen the)-5 E F1(NORM_NACK_INFO)93.6 370 Q F0
(flag is set, this indicates the r)2.5 E(eceiver is missing the)-.18 E
F1(NORM_INFO)2.5 E F0(segment)2.5 E
(for the indicated "object_transport_id".)93.6 382 Q(Note the)5 E F1
(NORM_NACK_INFO)2.5 E F0(may be set in)2.5 E(combination with the)93.6
394 Q F1(NORM_NACK_BLOCK)2.5 E F0(or)2.5 E F1(NORM_NACK_SEGMENT)2.5 E F0
(flags, or may be set)2.5 E 2.5(alone. When)93.6 406 R(the)2.5 E F1
(NORM_NACK_OBJECT)2.5 E F0(flag is set, this indicates the r)2.5 E
(eceiver is missing the)-.18 E(entir)93.6 418 Q(e)-.18 E/F2 10
/Palatino-Italic@0 SF(NormT)2.5 E(ransportObject)-1.11 E F0 -.18(re)2.5
G(fer).18 E(enced by the "object_transport_id".)-.18 E
(This also implicitly)5 E -.18(re)93.6 430 S(quests any available).18 E
F1(NORM_INFO)2.5 E F0(for the)2.5 E F2(NormObject)2.5 E F0 2.5(,i)C 2.5
(fa)-2.5 G 2.5(pplicable. The)-2.5 F("fec_payload_id")2.5 E
(field is ignor)93.6 442 Q(ed when the flag)-.18 E F1(NORM_NACK_OBJECT)
2.5 E F0(is set.)2.5 E
(The "length" field value is the length in bytes of the "r)93.6 466 Q
(epair_r)-.18 E(equest_items" field.)-.18 E(The "r)93.6 490 Q(epair_r)
-.18 E(equest_items" field consists of a list of individual or range pa\
irs of transport)-.18 E(data unit identifiers in the following format.)
93.6 502 Q F1 114(0123)99.6 526 S 6(01234567890123456789012345678901)
99.6 538 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
550 Q 30(|f)93.6 562 S 18(ec_id |)-30 F 18(reserved |)18 F 30
(object_transport_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
574 Q 144(|f)93.6 586 S 144(ec_payload_id |)-144 F 180(|.)93.6 598 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
610 Q F2(NORM Repair Request Item Format)224.815 634 Q F0(The "fec_id" \
indicates the FEC type and can be used to determine the format of the)
93.6 658 Q("fec_payload_id" field.)93.6 670 Q(The "r)5 E
(eserved" field is kept for possible futur)-.18 E 2.5(eu)-.18 G
(se and SHALL be set)-2.5 E(to a ZERO value and ignor)93.6 682 Q
(ed by NORM nodes pr)-.18 E(ocessing NACK content.)-.18 E
(The "object_transport_id" corr)93.6 706 Q(esponds to the)-.18 E F2
(NormObject)2.5 E F0(for which r)2.5 E(epair is being r)-.18 E(equested)
-.18 E(and the "fec_payload_id" identifies the specific FEC coding bloc\
k and/or segment being)93.6 718 Q(Adamson, et al.)72 768 Q(Expir)87.875
E(es: 31 December 2007)-.18 E([Page 40])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E -.18(re)93.6 120 S 2.5
(quested. When).18 F(the)2.5 E/F1 10/Courier@0 SF(NORM_NACK_OBJECT)2.5 E
F0(flag is set, the value of the "fec_payload_id" field)2.5 E(is ignor)
93.6 132 Q 2.5(ed. When)-.18 F(the)2.5 E F1(NORM_NACK_BLOCK)2.5 E F0
(flag is set, only the FEC code block identifier)2.5 E
(portion of the "fec_payload_id" is to be interpr)93.6 144 Q(eted.)-.18
E(The format of the "fec_payload_id" field depends upon the "fec_id" fi\
eld value.)93.6 168 Q(When the r)93.6 192 Q -1.76(eceiver 's)-.18 F -.18
(re)2.5 G(pair needs dictate that dif).18 E(fer)-.18 E
(ent forms \(mixed ranges and/or)-.18 E(individual items\) or types \(m\
ixed specific segments and/or blocks or objects in entir)93.6 204 Q
(ety\) ar)-.18 E(e)-.18 E -.18(re)93.6 216 S(quir).18 E
(ed to complete r)-.18 E
(eliable transmission, multiple NORM Repair Requests with dif)-.18 E
(fer)-.18 E(ent)-.18 E
("form" and or "flags" values can be concatenated within a single)93.6
228 Q F1(NORM_NACK)2.5 E F0(message.)2.5 E(Additionally)93.6 240 Q 2.5
(,N)-1.11 G(ORM r)-2.5 E(eceivers SHALL constr)-.18 E(uct)-.08 E F1
(NORM_NACK)2.5 E F0(messages with their r)2.5 E(epair)-.18 E -.18(re)
93.6 252 S(quests in or).18 E(dinal or)-.18 E(der with r)-.18 E
(espect to "object_transport_id" and "fec_payload_id" values.)-.18 E
(The "nack_payload" size SHALL NOT exceed the)93.6 264 Q/F2 10
/Palatino-Italic@0 SF(NormSegmentSize)2.5 E F0(for the sender to which)
2.5 E(the)93.6 276 Q F1(NORM_NACK)2.5 E F0(is destined.)2.5 E/F3 10
/Palatino-BoldItalic@0 SF(NORM_NACK Content Examples:)93.6 300 Q F0(In \
these examples, a small block, systematic FEC code \("fec_id" = 129\) i\
s assumed with a user)93.6 324 Q(data block length of 32 segments.)93.6
336 Q(In Example 1, a list of individual)5 E F1(NORM_NACK_ITEMS)2.5 E F0
-.18(re)93.6 348 S(pair r).18 E(equests is given.)-.18 E
(In Example 2, a list of)5 E F1(NORM_NACK_RANGES)2.5 E F0 -.18(re)2.5 G
(quests _and_ a single).18 E F1(NORM_NACK_ITEMS)93.6 360 Q F0 -.18(re)
2.5 G(quest ar).18 E 2.5(ec)-.18 G
(oncatenated to illustrate the possible content of a)-2.5 E F1
(NORM_NACK)93.6 372 Q F0 2.5(message. Note)2.5 F
(that FEC coding block erasur)2.5 E 2.5(ec)-.18 G
(ounts could also be pr)-2.5 E(ovided in)-.18 E(each case.)93.6 384 Q
(However)5 E 2.5(,t)-.74 G(he erasur)-2.5 E 2.5(ec)-.18 G(ounts ar)-2.5
E 2.5(en)-.18 G(ot r)-2.5 E(eally necessary since the sender can easily)
-.18 E(determine the erasur)93.6 396 Q 2.5(ec)-.18 G(ount while pr)-2.5
E(ocessing the NACK content.)-.18 E(However)5 E 2.5(,t)-.74 G(he erasur)
-2.5 E(e)-.18 E(count option may be useful for operation with other FEC\
 codes or for intermediate system)93.6 408 Q(purposes.)93.6 420 Q
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(Example 1:)93.6 120 Q/F1 10
/Courier@0 SF(NORM_NACK)5 E F0
("nack_payload" for: Object 12, Coding Block 3, Segments 2,5,8)2.5 E F1
114(0123)99.6 132 S 6(01234567890123456789012345678901)99.6 144 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
156 Q 18(|f)93.6 168 S(orm = 1)-18 E 6(|f)24 G(lags = 0x01)-6 E 42(|l)12
G 6(ength =)-42 F 66(36 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
180 Q 12(|f)93.6 192 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(2|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
204 Q 120(|s)93.6 216 S(ource_block_number = 3)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
228 Q 24(|s)93.6 240 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 2)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
252 Q 12(|f)93.6 264 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(2|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
276 Q 120(|s)93.6 288 S(ource_block_number = 3)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
300 Q 24(|s)93.6 312 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 5)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
324 Q 12(|f)93.6 336 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(2|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
348 Q 120(|s)93.6 360 S(ource_block_number = 3)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
372 Q 24(|s)93.6 384 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 8)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
396 Q F0(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)
-.18 E([Page 42])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(Example 2:)93.6 120 Q/F1 10
/Courier@0 SF(NORM_NACK)5 E F0
("nack_payload" for: Object 18 Coding Block 6, Segments 5, 6, 7, 8, 9,)
2.5 E(10; and Object 19)93.6 132 Q F1(NORM_INFO)2.5 E F0
(and Coding Block 1, segment 3)2.5 E F1 114(0123)99.6 144 S 6
(01234567890123456789012345678901)99.6 156 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 18(|f)93.6 180 S(orm = 2)-18 E 6(|f)24 G(lags = 0x01)-6 E 42(|l)12
G 6(ength =)-42 F 66(24 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 12(|f)93.6 204 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(8|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 120(|s)93.6 228 S(ource_block_number = 6)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
240 Q 24(|s)93.6 252 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 5)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
264 Q 12(|f)93.6 276 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(8|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
288 Q 120(|s)93.6 300 S(ource_block_number = 6)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
312 Q 24(|s)93.6 324 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 10)-24 E(|)24 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
336 Q 18(|f)93.6 348 S(orm = 1)-18 E 6(|f)24 G(lags = 0x05)-6 E 42(|l)12
G 6(ength =)-42 F 66(12 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
360 Q 12(|f)93.6 372 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(9|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
384 Q 120(|s)93.6 396 S(ource_block_number = 1)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
408 Q 24(|s)93.6 420 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 3)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
432 Q/F2 10/Palatino-Bold@0 SF 2.5(4.3.2. NORM_ACK)72 456 R(Message)2.5
E F0(The)93.6 471.6 Q F1(NORM_ACK)2.5 E F0
(message is intended to be used primarily as part of NORM congestion)2.5
E(contr)93.6 483.6 Q(ol operation and r)-.18 E(ound-trip timing measur)
-.18 E 2.5(ement. As)-.18 F(mentioned in the)2.5 E F1
(NORM_CMD\(ACK_REQ\))93.6 495.6 Q F0
(message description, the acknowledgment type)2.5 E F1(NORM_ACK_CC)2.5 E
F0(is)2.5 E(pr)93.6 507.6 Q(ovided for this purpose.)-.18 E
(The generation of)5 E F1(NORM_ACK\(CC\))2.5 E F0(messages for r)2.5 E
(ound-trip)-.18 E(timing estimation and congestion-contr)93.6 519.6 Q
(ol operation is described in Sections 5.5.1 and 5.5.2,)-.18 E -.18(re)
93.6 531.6 S(spectively).18 E 5(.H)-1.11 G(owever)-5 E 2.5(,s)-.74 G
(ome multicast applications may benefit fr)-2.5 E
(om some limited form of)-.18 E
(positive acknowledgment for certain functions.)93.6 543.6 Q 2.5(As)5 G
(imple, scalable positive acknowledgment)-2.5 E
(scheme is defined in Section 5.5.3 that can be leveraged by pr)93.6
555.6 Q(otocol implementations when)-.18 E(appr)93.6 567.6 Q 2.5
(opriate. The)-.18 F F1(NORM_CMD\(FLUSH\))2.5 E F0
(may be used for OPTIONAL collection of positive)2.5 E
(acknowledgment of r)93.6 579.6 Q(eliable r)-.18 E
(eception to a certain "watermark" transmission point fr)-.18 E(om)-.18
E(specific r)93.6 591.6 Q(eceivers using this mechanism.)-.18 E
(The NORM_ACK type)5 E F1(NORM_ACK_FLUSH)2.5 E F0(is)2.5 E(pr)93.6 603.6
Q(ovided for this purpose and the format of the "nack_payload" for this\
 acknowledgment)-.18 E(type is given below)93.6 615.6 Q 5(.B)-.92 G
(eyond that, a range of application-defined "ack_type" values is)-5 E
(pr)93.6 627.6 Q(ovided for use at the NORM application's discr)-.18 E
2.5(etion. Implementations)-.18 F(making use of)2.5 E(application-defin\
ed positive acknowledgments may also make use the "nack_payload" as)93.6
639.6 Q(needed, observing the constraint that the "nack_payload" field \
size be limited to a maximum)93.6 651.6 Q(of the)93.6 663.6 Q/F3 10
/Palatino-Italic@0 SF(NormSegmentSize)2.5 E F0
(for the sender to which the)2.5 E F1(NORM_ACK)2.5 E F0(is destined.)2.5
E(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q(|version| type=5|)93.6 156 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 162(|s)93.6 180 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
192 Q 162(|s)93.6 204 S 156(erver_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
216 Q 66(|i)93.6 228 S 48(nstance_id |)-66 F 6(ack_type |)24 F 24
(ack_id |)30 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
240 Q 138(|g)93.6 252 S 132(rtt_response_sec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
264 Q 138(|g)93.6 276 S 126(rtt_response_usec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
288 Q 90(|h)93.6 300 S(eader extensions \(if applicable\))-90 E(|)90 E
180(|.)93.6 312 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
324 Q 114(|a)93.6 336 S(ck_payload \(if applicable\))-114 E(|)102 E 180
(|.)93.6 348 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
360 Q/F2 10/Palatino-Italic@0 SF(NORM_ACK Message Format)235.745 384 Q
F0(The NORM common message header fields serve their usual purposes.)
93.6 408 Q(The value of the)5 E
("hdr_len" field when no header extensions ar)93.6 420 Q 2.5(ep)-.18 G
-.18(re)-2.5 G(sent is 6.).18 E(The "server_id", "instance_id",)93.6 444
Q(and "grtt_r)5 E(esponse" fields serve the same purpose as the)-.18 E
(corr)93.6 456 Q(esponding fields in)-.18 E F1(NORM_NACK)2.5 E F0 2.5
(messages. And)2.5 F(header extensions may be applied to)2.5 E
(support congestion contr)93.6 468 Q
(ol feedback or other functions in the same manner)-.18 E(.)-.74 E
(The "ack_type" field indicates the natur)93.6 492 Q 2.5(eo)-.18 G 2.5
(ft)-2.5 G(he)-2.5 E F1(NORM_ACK)2.5 E F0 2.5(message. This)2.5 F(dir)
2.5 E(ectly)-.18 E(corr)93.6 504 Q
(esponds to the "ack_type" field of the)-.18 E F1(NORM_CMD\(ACK_REQ\))
2.5 E F0(message to which this)2.5 E(acknowledgment applies.)93.6 516 Q
(The "ack_id" field serves as a sequence number so that the sender can \
verify that a)93.6 540 Q F1(NORM_ACK)93.6 552 Q F0(message r)2.5 E
(eceived actually applies to a curr)-.18 E(ent acknowledgment r)-.18 E
2.5(equest. The)-.18 F("ack_id" field is not used in the case of the)
93.6 564 Q F1(NORM_ACK_CC)2.5 E F0(and)2.5 E F1(NORM_ACK_FLUSH)2.5 E F0
(acknowledgment types.)93.6 576 Q
(The "ack_payload" format is a function of the "ack_type".)93.6 600 Q
(The)7.5 E F1(NORM_ACK_CC)2.5 E F0(message has)2.5 E
(no attached content.)93.6 612 Q(Only the)5 E F1(NORM_ACK)2.5 E F0
(header applies.)2.5 E(In the case of)5 E F1(NORM_ACK_FLUSH)2.5 E F0(,)A
2.5(as)93.6 624 S(pecific "ack_payload" format is defined:)-2.5 E
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Courier@0 SF 114(0123)
99.6 120 S 6(01234567890123456789012345678901)99.6 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
144 Q 30(|f)93.6 156 S 18(ec_id |)-30 F 18(reserved |)18 F 30
(object_transport_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
168 Q 144(|f)93.6 180 S 144(ec_payload_id |)-144 F 180(|.)93.6 192 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)93.6
204 Q/F2 10/Palatino-Italic@0 SF(NORM_ACK_FLUSH "ack_payload" Format)
204.82 228 Q F0(The "object_transport_id" and "fec_payload_id" ar)93.6
252 Q 2.5(eu)-.18 G(sed by the r)-2.5 E(eceiver to acknowledge)-.18 E
(applicable)93.6 264 Q F1(NORM_CMD\(FLUSH\))2.5 E F0
(messages transmitted by the sender identified by the)2.5 E
("server_id" field.)93.6 276 Q(The "ack_payload" of)93.6 300 Q F1
(NORM_ACK)2.5 E F0
(messages for application-defined "ack_type" values is)2.5 E
(specific to the application but is limited in size to a maximum the)
93.6 312 Q F2(NormSegmentSize)2.5 E F0(of the)2.5 E(sender r)93.6 324 Q
(efer)-.18 E(enced by the "server_id".)-.18 E/F3 10/Palatino-Bold@0 SF
(4.4.)72 348 Q/F4 12/Palatino-Bold@0 SF(General Purpose Messages)5 E F0
(Some additional message formats ar)93.6 363.6 Q 2.5(ed)-.18 G
(efined for general purpose in NORM multicast)-2.5 E
(sessions whether the participant is acting as a sender and/or r)93.6
375.6 Q(eceiver within the gr)-.18 E(oup.)-.18 E F3 2.5
(4.4.1. NORM_REPOR)72 399.6 R 2.5(TM)-.55 G(essage)-2.5 E F0
(This is an optional message generated by NORM participants.)93.6 415.2
Q(This message could be used)5 E(for periodic performance r)93.6 427.2 Q
(eports fr)-.18 E(om r)-.18 E
(eceivers in experimental NORM implementations.)-.18 E
(The format of this message is curr)93.6 439.2 Q(ently undefined.)-.18 E
(Experimental NORM implementations)5 E(may define NORM_REPOR)93.6 451.2
Q 2.5(Tf)-.37 G(ormats as needed for test purposes.)-2.5 E(These r)5 E
(eport messages)-.18 E(SHOULD be disabled for inter)93.6 463.2 Q
(operability testing between dif)-.18 E(fer)-.18 E
(ent NORM implementations.)-.18 E F3(5.)72 487.2 Q/F5 13/Palatino-Bold@0
SF(Detailed Protocol Operation)5 E F0
(This section describes the detailed interactions of senders and r)93.6
502.8 Q(eceivers participating in a)-.18 E(NORM session.)93.6 514.8 Q
2.5(As)5 G(imple synopsis of pr)-2.5 E(otocol operation is given her)
-.18 E(e:)-.18 E(1\))72 544.8 Q(The sender periodically transmits)95.33
544.8 Q F1(NORM_CMD\(CC\))2.5 E F0
(messages as needed to initialize and collect)2.5 E -.18(ro)95.33 556.8
S(undtrip timing and congestion contr).18 E(ol feedback fr)-.18 E
(om the r)-.18 E(eceiver set.)-.18 E(2\))72 580.8 Q
(The sender transmits an or)95.33 580.8 Q(dinal set of)-.18 E F2
(NormObjects)2.5 E F0(segmented in the form of)2.5 E F1(NORM_DATA)2.5 E
F0(messages labeled with)95.33 592.8 Q F2(NormT)2.5 E(ransportIds)-1.11
E F0(and logically identified with FEC encoding block)2.5 E
(numbers and symbol identifiers.)95.33 604.8 Q F1(NORM_INFO)5 E F0
(messages may optionally pr)2.5 E(ecede the transmission)-.18 E
(of data content for NORM transport objects.)95.33 616.8 Q(3\))72 640.8
Q(As r)95.33 640.8 Q(eceivers detect missing content fr)-.18 E
(om the sender)-.18 E 2.5(,t)-.74 G(hey initiate r)-2.5 E(epair r)-.18 E
(equests with)-.18 E F1(NORM_NACK)95.33 652.8 Q F0 2.5(messages. Note)
2.5 F(the r)2.5 E(eceivers track the sender)-.18 E('s most r).74 E
(ecent)-.18 E F2(objectId::fecPayloadId)2.5 E F0
(transmit position and NACK _only_ for content or)95.33 664.8 Q
(dinally prior to that transmit position.)-.18 E(The)5 E -.18(re)95.33
676.8 S(ceivers schedule random backof).18 E 2.5(ft)-.18 G
(imeouts befor)-2.5 E 2.5(eg)-.18 G(enerating)-2.5 E F1(NORM_NACK)2.5 E
F0(messages and wait an)2.5 E(appr)95.33 688.8 Q
(opriate amount of time befor)-.18 E 2.5(er)-.18 G(epeating the)-2.68 E
F1(NORM_NACK)2.5 E F0(if their r)2.5 E(epair r)-.18 E(equest is not)-.18
E(satisfied.)95.33 700.8 Q(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(4\))72 120 Q(The sender aggr)
95.33 120 Q(egates r)-.18 E(epair r)-.18 E(equests fr)-.18 E(om the r)
-.18 E(eceivers and logically "r)-.18 E(ewinds" its transmit)-.18 E
(position to send appr)95.33 132 Q(opriate r)-.18 E(epair messages.)-.18
E(The sender sends r)5 E(epairs for the earliest or)-.18 E(dinal)-.18 E
(transmit position first and maintains this or)95.33 144 Q(dinal r)-.18
E(epair transmission sequence.)-.18 E(Pr)5 E(eviously)-.18 E(untransmit\
ted FEC parity content for the applicable FEC coding block is used for \
r)95.33 156 Q(epair)-.18 E(transmissions to the gr)95.33 168 Q
(eatest extent possible.)-.18 E
(If the sender exhausts its available FEC parity)5 E
(content on multiple r)95.33 180 Q
(epair cycles for the same coding block, it r)-.18 E
(esorts to an explicit r)-.18 E(epair strategy)-.18 E
(\(possibly using parity content\) to complete r)95.33 192 Q 2.5
(epairs. \(The)-.18 F(use of explicit r)2.5 E
(epair is expected to be an)-.18 E(exception in general pr)95.33 204 Q
(otocol operation, but the possibility does exist for extr)-.18 E
(eme conditions\).)-.18 E(The sender immediately assumes transmission o\
f new content once it has sent pending r)95.33 216 Q(epairs.)-.18 E(5\))
72 240 Q(The sender transmits)95.33 240 Q/F1 10/Courier@0 SF
(NORM_CMD\(FLUSH\))2.5 E F0(messages when it r)2.5 E
(eaches the end of enqueued)-.18 E(transmit content and pending r)95.33
252 Q 2.5(epairs. Receivers)-.18 F -.18(re)2.5 G(spond to the).18 E F1
(NORM_CMD\(FLUSH\))2.5 E F0(messages)2.5 E(with)95.33 264 Q F1
(NORM_NACK)2.5 E F0(transmissions \(following the same suppr)2.5 E
(ession backof)-.18 E 2.5(ft)-.18 G(imeout strategy as for)-2.5 E
(data\) if they r)95.33 276 Q(equir)-.18 E 2.5(ef)-.18 G(urther r)-2.5 E
(epair)-.18 E(.)-.74 E(6\))72 300 Q(The sender transmissions ar)95.33
300 Q 2.5(es)-.18 G(ubject to rate contr)-2.5 E
(ol limits determined by congestion contr)-.18 E(ol)-.18 E 2.5
(mechanisms. In)95.33 312 R
(the baseline NORM-CC operation, each sender in a)2.5 E/F2 10
/Palatino-Italic@0 SF(NormSession)2.5 E F0(maintains its)2.5 E
(own independent congestion contr)95.33 324 Q(ol state.)-.18 E
(Receivers pr)5 E(ovide congestion contr)-.18 E(ol feedback in)-.18 E F1
(NORM_NACK)95.33 336 Q F0(and)2.5 E F1(NORM_ACK)2.5 E F0(messages.)2.5 E
F1(NORM_ACK)5 E F0(feedback for congestion contr)2.5 E(ol purposes is)
-.18 E(governed using a suppr)95.33 348 Q
(ession mechanism similar to that for)-.18 E F1(NORM_NACK)2.5 E F0
(messages.)2.5 E(While this overall concept is r)93.6 378 Q
(elatively simple, ther)-.18 E 2.5(ea)-.18 G .36 -.18(re d)-2.5 H
(etails to each of these aspects that).18 E(need to be addr)93.6 390 Q
(essed for successful, ef)-.18 E(ficient, r)-.18 E
(obust, and scalable NORM pr)-.18 E(otocol operation.)-.18 E/F3 10
/Palatino-Bold@0 SF(5.1.)72 414 Q/F4 12/Palatino-Bold@0 SF
(Sender Initialization and T)5 E(ransmission)-1.332 E F0
(Upon startup, the NORM sender immediately begins sending)93.6 429.6 Q
F1(NORM_CMD\(CC\))2.5 E F0(messages to)2.5 E(collect r)93.6 441.6 Q
(ound trip timing and other information fr)-.18 E(om the potential gr)
-.18 E 2.5(oup. If)-.18 F(NORM-CC)2.5 E(congestion contr)93.6 453.6 Q
(ol operation is enabled, the NORM-CC Rate header extension MUST be)-.18
E(included in these messages.)93.6 465.6 Q(Congestion contr)5 E
(ol operation SHALL be observed at all times)-.18 E
(when operating in the general Internet.)93.6 477.6 Q
(Even if congestion contr)5 E(ol operation is disabled at)-.18 E
(the sender)93.6 489.6 Q 2.5(,i)-.74 G 2.5(tm)-2.5 G
(ay be desirable to use the)-2.5 E F1(NORM_CMD\(CC\))2.5 E F0
(messaging to collect feedback)2.5 E(fr)93.6 501.6 Q(om the gr)-.18 E
(oup using the baseline NORM-CC feedback mechanisms.)-.18 E(This pr)5 E
(oactive)-.18 E(feedback collection can be used to establish a GR)93.6
513.6 Q(TT estimate prior to data transmission and)-.37 E
(potential NACK operation.)93.6 525.6 Q
(In some cases, applications may wish for the sender to also pr)93.6
549.6 Q(oceed with data transmission)-.18 E(immediately)93.6 561.6 Q 5
(.I)-1.11 G 2.5(no)-5 G(ther cases, the sender may wish to defer data t\
ransmission until it has)-2.5 E -.18(re)93.6 573.6 S
(ceived some feedback or r).18 E(equest fr)-.18 E(om the r)-.18 E
(eceiver set indicating that r)-.18 E(eceivers ar)-.18 E 2.5(ei)-.18 G
(ndeed)-2.5 E(pr)93.6 585.6 Q 2.5(esent. Note,)-.18 F(in some applicati\
ons \(e.g., web push\), this indication may come out-of-band)2.5 E
(with r)93.6 597.6 Q(espect to the multicast session via other means.)
-.18 E(As noted, the periodic transmission of)5 E F1(NORM_CMD\(CC\))93.6
609.6 Q F0(messages may pr)2.5 E(ecede actual data transmission in or)
-.18 E(der to have an initial)-.18 E(GR)93.6 621.6 Q(TT estimate.)-.37 E
-.55(Wi)93.6 645.6 S(th inclusion of the OPTIONAL NORM FEC Object T).55
E(ransmission Information Header)-.9 E
(Extension \(EXT_FTI\), the NORM pr)93.6 657.6 Q
(otocol sender message headers can contain all)-.18 E
(information necessary to pr)93.6 669.6 Q(epar)-.18 E 2.5(er)-.18 G
(eceivers for subsequent r)-2.68 E(eliable r)-.18 E 2.5(eception. This)
-.18 F(includes)2.5 E(FEC coding parameters, the sender)93.6 681.6 Q F2
(NormSegmentSize)2.5 E F0 2.5(,a)C(nd other information.)-2.5 E
(If this header)5 E(extension is not used, it is pr)93.6 693.6 Q
(esumed that r)-.18 E(eceivers have r)-.18 E(eceived the FEC Object)-.18
E -.9(Tr)93.6 705.6 S(ansmission Information via other means.).9 E
(Additionally)7.5 E 2.5(,a)-1.11 G(pplications may leverage the use)-2.5
E(of)93.6 717.6 Q F1(NORM_INFO)2.5 E F0
(messages associated with the session data objects in the session to pr)
2.5 E(ovide)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(application-specific context i\
nformation for the session and data being transmitted.)93.6 120 Q(These)
5 E(mechanisms allow for operation with minimal pr)93.6 132 Q(e-coor)
-.18 E(dination among the senders and)-.18 E -.18(re)93.6 144 S
(ceivers.).18 E
(The NORM sender begins segmenting application-enqueued data into)93.6
168 Q/F1 10/Courier@0 SF(NORM_DATA)2.5 E F0
(segments and transmitting it to the gr)93.6 180 Q 2.5(oup. For)-.18 F
(objects of type)2.5 E F1(NORM_OBJECT_DATA)2.5 E F0(and)2.5 E F1
(NORM_OBJECT_FILE)93.6 192 Q F0 2.5(,t)C
(he segmentation algorithm described in FEC Building Block)-2.5 E 2.5
(document. [4]. is)93.6 204 R 2.5(RECOMMENDED. For)2.5 F
(objects of type)2.5 E F1(NORM_OBJECT_STREAM)2.5 E F0(,)A(segmentation \
will typically be done into uniform FEC coding block sizes, with indivi\
dual)93.6 216 Q(segment sizes contr)93.6 228 Q
(olled by the application, although in many cases, the application and)
-.18 E(NORM implementation should strive to pr)93.6 240 Q
(oduce full-sized \(NormSegmentSize\) segments)-.18 E(when possible.)
93.6 252 Q(The rate of transmission is contr)5 E
(olled via congestion contr)-.18 E(ol mechanisms or)-.18 E
(is a fixed rate if desir)93.6 264 Q(ed for closed network operations.)
-.18 E(The r)5 E(eceivers participating in the)-.18 E(multicast gr)93.6
276 Q(oup pr)-.18 E(ovide feedback to the sender as needed.)-.18 E
(When the sender r)5 E(eaches the end)-.18 E
(of data it has enqueued for transmission or any pending r)93.6 288 Q
(epairs, it transmits a series of)-.18 E F1(NORM_CMD\(FLUSH\))93.6 300 Q
F0(messages at a rate of one per)2.5 E F1(2*GRTT)2.5 E F0 5(.R)C
(eceivers may r)-5 E(espond to these)-.18 E F1(NORM_CMD\(FLUSH\))93.6
312 Q F0(messages with additional r)2.5 E(epair r)-.18 E 2.5(equests. A)
-.18 F(pr)2.5 E(otocol parameter)-.18 E(")93.6 324 Q F1
(NORM_ROBUST_FACTOR)A F0 2.5("d)C
(etermines the number of flush messages sent.)-2.5 E(If r)5 E(eceivers)
-.18 E -.18(re)93.6 336 S(quest r).18 E(epair)-.18 E 2.5(,t)-.74 G(he r)
-2.5 E(epair is pr)-.18 E
(ovided and flushing occurs again at the end of r)-.18 E(epair)-.18 E
2.5(transmission. The)93.6 348 R
(sender may attach an OPTIONAL "acking_node_list" to)2.5 E F1
(NORM_CMD\(FLUSH\))93.6 360 Q F0(containing the)2.5 E/F2 10
/Palatino-Italic@0 SF(NormNodeIds)2.5 E F0(for r)2.5 E(eceivers fr)-.18
E(om which it expects explicit)-.18 E(positive acknowledgment of r)93.6
372 Q 2.5(eception. The)-.18 F F1(NORM_CMD\(FLUSH\))2.5 E F0
(message may be also used)2.5 E(for this optional function any time pri\
or to the end of data enqueued for transmission with)93.6 384 Q(the)93.6
396 Q F1(NORM_CMD\(FLUSH\))2.5 E F0
(messages multiplexed with ongoing data transmissions.)2.5 E(The)5 E
(OPTIONAL NORM positive acknowledgment pr)93.6 408 Q(ocedur)-.18 E 2.5
(ei)-.18 G 2.5(sd)-2.5 G(escribed in Section 5.5.3.)-2.5 E/F3 10
/Palatino-Bold@0 SF 2.5(5.1.1. Object)72 432 R(Segmentation Algorithm)
2.5 E F0(NORM senders and r)93.6 447.6 Q
(eceivers MUST use a common algorithm for logically segmenting)-.18 E
(transport data into FEC encoding blocks and symbols so that appr)93.6
459.6 Q(opriate NACKs can be)-.18 E(constr)93.6 471.6 Q(ucted to r)-.08
E(equest r)-.18 E(epair of missing data.)-.18 E
(NORM FEC coding blocks ar)5 E 2.5(ec)-.18 G(omprised of)-2.5 E
(multi-byte symbols \(segments\) that ar)93.6 483.6 Q 2.5(et)-.18 G
(ransmitted in the payload of)-2.5 E F1(NORM_DATA)2.5 E F0(messages.)2.5
E(Each)93.6 495.6 Q F1(NORM_DATA)2.5 E F0
(message will contain one or mor)2.5 E 2.5(es)-.18 G(our)-2.5 E
(ce or encoding symbol\(s\) identified)-.18 E
(by the "fec_payload_id" field and the)93.6 507.6 Q F2(NormSegmentSize)
2.5 E F0(sender parameter defines the)2.5 E(maximum size \(in bytes\) o\
f the "payload_data" field containing the content \(a "segment"\).)93.6
519.6 Q(The FEC encoding type and associated parameters govern the sour)
93.6 531.6 Q(ce block size \(number of)-.18 E(sour)93.6 543.6 Q
(ce symbols per coding block, etc.\).)-.18 E(NORM senders and r)5 E
(eceivers use these FEC)-.18 E(parameters, along with the)93.6 555.6 Q
F2(NormSegmentSize)2.5 E F0
(and transport object size to compute the sour)2.5 E(ce)-.18 E
(block str)93.6 567.6 Q(uctur)-.08 E 2.5(ef)-.18 G
(or transport objects.)-2.5 E(These parameters ar)5 E 2.5(ep)-.18 G -.18
(ro)-2.5 G(vided in the FEC Object).18 E -.9(Tr)93.6 579.6 S
(ansmission Information for each object.).9 E
(The block partioning algorithm described in the)5 E
(FEC Building Block document [4])93.6 591.6 Q
(is RECOMMENDED for use to compute a sour)5 E(ce block)-.18 E(str)93.6
603.6 Q(uctur)-.08 E 2.5(es)-.18 G(uch that all sour)-2.5 E
(ce blocks ar)-.18 E 2.5(ea)-.18 G 2.5(sc)-2.5 G
(lose to being equal length as possible.)-2.5 E(This helps)5 E
(avoid the performance disadvantages of "short" FEC blocks.)93.6 615.6 Q
(Note this algorithm applies)5 E(only to the statically-sized)93.6 627.6
Q F1(NORM_OBJECT_DATA)2.5 E F0(and)2.5 E F1(NORM_OBJECT_FILE)2.5 E F0
(transport object)2.5 E(types wher)93.6 639.6 Q 2.5(et)-.18 G
(he object size is fixed and pr)-2.5 E 2.5(edetermined. For)-.18 F F1
(NORM_OBJECT_STREAM)2.5 E F0(objects,)2.5 E
(the object is segmented accor)93.6 651.6 Q(ding to the maximum sour)
-.18 E(ce block length given in the FEC)-.18 E -.9(Tr)93.6 663.6 S(ansm\
ission Information, unless the FEC Payload ID indicates an alternative \
size for a).9 E(given block.)93.6 675.6 Q(Adamson, et al.)72 768 Q
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Palatino-Bold@0 SF(5.2.)
72 120 Q/F2 12/Palatino-Bold@0 SF(Receiver Initialization and Reception)
5 E F0(The NORM pr)93.6 135.6 Q(otocol is designed such that r)-.18 E
(eceivers may join and leave the gr)-.18 E(oup at will.)-.18 E(However)
93.6 147.6 Q 2.5(,s)-.74 G
(ome applications may be constrained such that r)-2.5 E
(eceivers need to be members of)-.18 E(the gr)93.6 159.6 Q
(oup prior to start of data transmission.)-.18 E
(NORM applications may use dif)5 E(fer)-.18 E(ent policies)-.18 E
(to constrain the impact of new r)93.6 171.6 Q(eceivers joining the gr)
-.18 E(oup in the middle of a session.)-.18 E(For)5 E
(example, a useful implementation policy is for new r)93.6 183.6 Q
(eceivers joining the gr)-.18 E(oup to limit or)-.18 E(avoid r)93.6
195.6 Q(epair r)-.18 E(equests for transport objects alr)-.18 E
(eady in pr)-.18 E(ogr)-.18 E 2.5(ess. The)-.18 F(NORM sender)2.5 E(imp\
lementation may wish to impose additional constraints to limit the abil\
ity of r)93.6 207.6 Q(eceivers to)-.18 E(disr)93.6 219.6 Q(upt r)-.08 E
(eliable multicast performance by joining, leaving, and r)-.18 E
(ejoining the gr)-.18 E(oup often.)-.18 E(Dif)93.6 231.6 Q(fer)-.18 E
(ent r)-.18 E(eceiver "join policies" may be appr)-.18 E
(opriate for dif)-.18 E(fer)-.18 E(ent applications and/or)-.18 E 2.5
(scenarios. For)93.6 243.6 R
(general purpose operation, a default policy wher)2.5 E 2.5(er)-.18 G
(eceivers ar)-2.68 E 2.5(ea)-.18 G(llowed to)-2.5 E -.18(re)93.6 255.6 S
(quest r).18 E(epair only for coding blocks with a)-.18 E/F3 10
/Palatino-Italic@0 SF(NormT)2.5 E(ransportId)-1.11 E F0
(and FEC coding block number)2.5 E(gr)93.6 267.6 Q
(eater than or equal to the first non-r)-.18 E(epair)-.18 E/F4 10
/Courier@0 SF(NORM_DATA)2.5 E F0(or)2.5 E F4(NORM_INFO)2.5 E F0
(message r)2.5 E(eceived)-.18 E(upon joining the gr)93.6 279.6 Q
(oup is RECOMMENDED.)-.18 E(For objects of type)5 E F4
(NORM_OBJECT_STREAM)2.5 E F0(it)2.5 E
(is RECOMMENDED that the join policy constrain r)93.6 291.6 Q
(eceivers to start r)-.18 E(eliable r)-.18 E(eception at the)-.18 E
(curr)93.6 303.6 Q(ent FEC coding block for which non-r)-.18 E
(epair content is r)-.18 E(eceived.)-.18 E
(For typical operation, it is expected that NORM r)93.6 327.6 Q
(eceivers will join a specified multicast)-.18 E(gr)93.6 339.6 Q
(oup and/or listen on an specific port number for sender transmissions.)
-.18 E(As the NORM)5 E -.18(re)93.6 351.6 S(ceiver r).18 E(eceives)-.18
E F4(NORM_DATA)2.5 E F0(messages it will pr)2.5 E
(ovide content to its application as)-.18 E(appr)93.6 363.6 Q(opriate.)
-.18 E F1(5.3.)72 399.6 Q F2(Receiver NACK Procedure)5 E F0(When the r)
93.6 415.2 Q(eceiver detects it is missing data fr)-.18 E(om a sender)
-.18 E('s NORM transmissions, it initiates).74 E(its NACKing pr)93.6
427.2 Q(ocedur)-.18 E 2.5(e. The)-.18 F(NACKing pr)2.5 E(ocedur)-.18 E
2.5(eS)-.18 G(HALL be initiated _only_ at FEC coding)-2.5 E
(block boundaries,)93.6 439.2 Q F3(NormObject)2.5 E F0
(boundaries, upon r)2.5 E(eceipt of a)-.18 E F4(NORM_CMD\(FLUSH\))2.5 E
F0(message, or)2.5 E(upon an "inactivity" timeout when)93.6 451.2 Q F4
(NORM_DATA)2.5 E F0(or)2.5 E F4(NORM_INFO)2.5 E F0(transmissions ar)2.5
E 2.5(en)-.18 G 2.5(ol)-2.5 G(onger)-2.5 E -.18(re)93.6 463.2 S
(ceived fr).18 E(om a pr)-.18 E(eviously active sender)-.18 E 5(.T)-.74
G(he RECOMMENDED value of such an inactivity)-5 E(timeout is:)93.6 475.2
Q F4(T_inactivity = NORM_ROBUST_FACTOR * 2 * GRTTSender)148.8 487.2 Q F0
(wher)93.6 511.2 Q 2.5(et)-.18 G(he ")-2.5 E F4(GRTTsender)A F0 2.5("v)C
(alue corr)-2.5 E(esponds to the GR)-.18 E
(TT estimate advertised in the "grtt")-.37 E
(field of NORM sender messages.)93.6 523.2 Q 2.5(Am)5 G(inimum ")-2.5 E
F4(T_inactivity)A F0 2.5("v)C(alue of 1 second is)-2.5 E 2.5
(RECOMMENDED. The)93.6 535.2 R(NORM r)2.5 E(eceiver SHOULD r)-.18 E
(eset this inactivity timer and r)-.18 E(epeat)-.18 E
(NACK initiation upon timeout for up to)93.6 547.2 Q F4
(NORM_ROBUST_FACTOR)2.5 E F0(times or mor)2.5 E 2.5(ed)-.18 G(epending)
-2.5 E(upon the application's need for persistence by its r)93.6 559.2 Q
2.5(eceivers. It)-.18 F(is also important that)2.5 E -.18(re)93.6 571.2
S(ceivers r).18 E(escale the ")-.18 E F4(T_inactivity)A F0 2.5("t)C
(imeout as the sender)-2.5 E('s advertised GR).74 E(TT changes.)-.37 E
(The NACKing pr)93.6 595.2 Q(ocedur)-.18 E 2.5(eb)-.18 G
(egins with a random backof)-2.5 E 2.5(ft)-.18 G 2.5(imeout. The)-2.5 F
(duration of the)2.5 E(backof)93.6 607.2 Q 2.5(ft)-.18 G
(imeout is chosen using the "RandomBackof)-2.5 E
(f" algorithm described in the NORM)-.18 E
(Building Block document [3] using \()93.6 619.2 Q F4
(Ksender*GRTTsender)A F0 2.5(\)f)C(or the "maxT)-2.5 E(ime" parameter)
-.55 E(and the sender advertised gr)93.6 631.2 Q(oup size \()-.18 E F4
(GSIZEsender)A F0 2.5(\)a)C 2.5(st)-2.5 G(he "gr)-2.5 E
(oupSize" parameter)-.18 E 5(.N)-.74 G(ORM)-5 E(senders pr)93.6 643.2 Q
(ovide values for)-.18 E F4(GRTTsender)2.5 E F0(,)A F4(Ksender)2.5 E F0
(and)2.5 E F4(GSIZEsender)2.5 E F0(via the "grtt",)2.5 E("backof)93.6
655.2 Q(f", and "gsize" fields of transmitted messages.)-.18 E(The)5 E
F4(GRTTsender)2.5 E F0(value is determined)2.5 E
(by the sender based on feedback it has r)93.6 667.2 Q(eceived fr)-.18 E
(om the gr)-.18 E(oup while the)-.18 E F4(Ksender)2.5 E F0(and)2.5 E F4
(GSIZEsender)93.6 679.2 Q F0(values may determined by application r)2.5
E(equir)-.18 E(ements and expectations or)-.18 E(ancillary information.)
93.6 691.2 Q(The backof)5 E 2.5(ff)-.18 G(actor ")-2.5 E F4(Ksender)A F0
2.5("M)C(UST be gr)-2.5 E(eater than)-.18 E F4(one)2.5 E F0(to pr)2.5 E
(ovide)-.18 E(for ef)93.6 703.2 Q(fective feedback suppr)-.18 E 2.5
(ession. A)-.18 F(value of)2.5 E F4 6(K=4)2.5 G F0
(is RECOMMENDED for the Any)-3.5 E(Sour)93.6 715.2 Q
(ce Multicast \(ASM\) model while a value of)-.18 E F4 6(K=6)2.5 G F0
(is RECOMMENDED for Single)-3.5 E(Adamson, et al.)72 768 Q(Expir)87.875
E(es: 31 December 2007)-.18 E([Page 48])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(Sour)93.6 120 Q
(ce Multicast \(SSM\) operation.)-.18 E(Thus:)93.6 144 Q/F1 10/Courier@0
SF(T_backoff = RandomBackoff\(Ksender*GRTTsender, GSIZEsender\))124.8
168 Q F0 1.84 -.92(To a)93.6 192 T(void the possibility of NACK implosi\
on in the case of sender or network failur).92 E 2.5(ed)-.18 G(uring)
-2.5 E(SSM operation, the r)93.6 204 Q
(eceiver SHALL automatically suppr)-.18 E(ess its NACK and immediately)
-.18 E(enter the "holdof)93.6 216 Q(f" period described below when)-.18
E F1(T_backoff)2.5 E F0(is gr)2.5 E(eater than)-.18 E F1
(\(Ksender-1\)*GRTTsender)93.6 228 Q F0 5(.O)C(therwise, the backof)-5 E
2.5(fp)-.18 G(eriod is enter)-2.5 E(ed and the r)-.18 E(eceiver)-.18 E
(MUST accumulate external pending r)93.6 240 Q(epair state fr)-.18 E(om)
-.18 E F1(NORM_NACK)2.5 E F0(messages and)2.5 E F1
(NORM_CMD\(REPAIR_ADV\))93.6 252 Q F0(messages r)2.5 E 2.5(eceived. At)
-.18 F(the end of the backof)2.5 E 2.5(ft)-.18 G(ime, the r)-2.5 E
(eceiver)-.18 E(SHALL generate a)93.6 264 Q F1(NORM_NACK)2.5 E F0
(message only if the following conditions ar)2.5 E 2.5(em)-.18 G(et:)
-2.5 E(1\))93.6 294 Q(The sender)116.93 294 Q('s curr).74 E
(ent transmit position \(in terms of)-.18 E/F2 10/Palatino-Italic@0 SF
(objectId::fecPayloadId)2.5 E F0 2.5(\)e)C(xceeds the earliest)-2.5 E
-.18(re)116.93 306 S(pair position of the r).18 E(eceiver)-.18 E(.)-.74
E(2\))93.6 330 Q(The r)116.93 330 Q(epair state accumulated fr)-.18 E
(om)-.18 E F1(NORM_NACK)2.5 E F0(and)2.5 E F1(NORM_CMD\(REPAIR_ADV\))2.5
E F0(messages do not)2.5 E(equal or supersede the r)116.93 342 Q -1.76
(eceiver 's)-.18 F -.18(re)2.5 G
(pair needs up to the sender transmission position at the time).18 E
(the NACK pr)116.93 354 Q(ocedur)-.18 E 2.5(e\()-.18 G(backof)-2.5 E 2.5
(ft)-.18 G(imeout\) was initiated.)-2.5 E(If these conditions ar)93.6
384 Q 2.5(em)-.18 G(et, the r)-2.5 E(eceiver immediately generates a)
-.18 E F1(NORM_NACK)2.5 E F0(message when)2.5 E(the backof)93.6 396 Q
2.5(ft)-.18 G(imeout expir)-2.5 E 2.5(es. Otherwise,)-.18 F(the r)2.5 E
-1.76(eceiver 's)-.18 F(NACK is consider)2.5 E(ed to be)-.18 E("suppr)
93.6 408 Q(essed" and the message is not sent.)-.18 E
(At this time, the r)5 E(eceiver begins a "holdof)-.18 E(f" period)-.18
E(during which it constrains itself to not r)93.6 420 Q
(einitiate the NACKing pr)-.18 E 2.5(ocess. The)-.18 F(purpose of this)
2.5 E(timeout is to allow the sender worst-case time to r)93.6 432 Q
(espond to the r)-.18 E(epair needs befor)-.18 E 2.5(et)-.18 G(he)-2.5 E
-.18(re)93.6 444 S(ceiver r).18 E(equests r)-.18 E(epair again.)-.18 E
(The value of this "holdof)5 E(f" timeout)-.18 E(\()5 E F1
(T_rcvrHoldoff)A F0 2.5(\)a)C(s)-2.5 E(described in [3] is:)93.6 456 Q
F1(T_rcvrHoldoff =\(Ksender+2\)*GRTTsender)187.8 480 Q F0(The)93.6 504 Q
F1(NORM_NACK)2.5 E F0(message contains r)2.5 E(epair r)-.18 E
(equest content beginning with lowest or)-.18 E(dinal)-.18 E -.18(re)
93.6 516 S(pair position of the r).18 E(eceiver up thr)-.18 E
(ough the coding block prior to the most r)-.18 E(ecently hear)-.18 E(d)
-.18 E(or)93.6 528 Q(dinal transmission position for the sender)-.18 E 5
(.I)-.74 G 2.5(ft)-5 G(he size of the)-2.5 E F1(NORM_NACK)2.5 E F0
(content exceeds)2.5 E(the sender)93.6 540 Q('s).74 E F2
(NormSegmentSize)2.5 E F0 2.5(,t)C(he NACK content is tr)-2.5 E
(uncated so that the r)-.08 E(eceiver only)-.18 E(generates a single)
93.6 552 Q F1(NORM_NACK)2.5 E F0
(message per NACK cycle for a given sender)2.5 E 5(.I)-.74 G 2.5(ns)-5 G
(ummary)-2.5 E 2.5(,a)-1.11 G
(single NACK message is generated containing the r)93.6 564 Q -1.76
(eceiver 's)-.18 F(lowest or)2.5 E(dinal r)-.18 E(epair needs.)-.18 E
(For each partially-r)93.6 588 Q(eceived FEC coding block r)-.18 E
(equiring r)-.18 E(epair)-.18 E 2.5(,t)-.74 G(he r)-2.5 E
(eceiver SHALL, on its)-.18 E(_first_ r)93.6 600 Q
(epair attempt for the block, r)-.18 E
(equest the parity portion of the FEC coding block)-.18 E
(beginning with the lowest or)93.6 612 Q
(dinal _parity_ "encoding_symbol_id" \(i.e.,)-.18 E
("encoding_symbol_id" = "sour)93.6 624 Q(ce_block_len"\) and r)-.18 E
(equest the number of FEC symbols)-.18 E(corr)93.6 636 Q
(esponding to its data segment erasur)-.18 E 2.5(ec)-.18 G
(ount for the block.)-2.5 E(On _subsequent_ r)5 E(epair)-.18 E
(cycles for the same coding block, the r)93.6 648 Q(eceiver SHALL r)-.18
E(equest only those r)-.18 E(epair symbols)-.18 E(fr)93.6 660 Q
(om the first set it has not yet r)-.18 E(eceived up to the r)-.18 E
(emaining erasur)-.18 E 2.5(ec)-.18 G(ount for that applicable)-2.5 E
(coding block.)93.6 672 Q(Note that the sender may have pr)5 E
(ovided other dif)-.18 E(fer)-.18 E(ent, additional parity)-.18 E
(segments for other r)93.6 684 Q
(eceivers that could also be used to satisfy the local r)-.18 E -1.76
(eceiver 's)-.18 F(erasur)2.5 E(e-)-.18 E(filling needs.)93.6 696 Q
(In the case wher)5 E 2.5(et)-.18 G(he erasur)-2.5 E 2.5(ec)-.18 G
(ount for a partially-r)-2.5 E(eceived FEC coding block)-.18 E
(exceeds the maximum number of parity symbols available fr)93.6 708 Q
(om the sender for the block \(as)-.18 E(indicated by the)93.6 720 Q F1
(NORM_DATA)2.5 E F0("fec_num_parity" field\), the r)2.5 E
(eceiver SHALL r)-.18 E(equest all)-.18 E(Adamson, et al.)72 768 Q
(Expir)87.875 E(es: 31 December 2007)-.18 E([Page 49])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(available parity segments plus the or)93.6 120 Q
(dinally highest missing data segments r)-.18 E(equir)-.18 E(ed to)-.18
E(satisfy its total erasur)93.6 132 Q 2.5(en)-.18 G(eeds for the block.)
-2.5 E(The goal of this strategy is for the overall)5 E -.18(re)93.6 144
S(ceiver set to r).18 E(equest a lowest common denominator set of r)-.18
E(epair symbols for a given FEC)-.18 E(coding block.)93.6 156 Q
(This allows the sender to constr)5 E(uct the most ef)-.08 E(ficient r)
-.18 E(epair transmission)-.18 E(segment set and enables ef)93.6 168 Q
(fective NACK suppr)-.18 E(ession among the r)-.18 E(eceivers even with)
-.18 E(uncorr)93.6 180 Q(elated packet loss.)-.18 E(This appr)5 E
(oach also r)-.18 E(equir)-.18 E(es no synchr)-.18 E
(onization among the)-.18 E -.18(re)93.6 192 S(ceiver set in their r).18
E(epair r)-.18 E(equests for the sender)-.18 E(.)-.74 E
(For FEC coding blocks or)93.6 216 Q/F1 10/Palatino-Italic@0 SF
(NormObjects)2.5 E F0(missed in their entir)2.5 E(ety)-.18 E 2.5(,t)
-1.11 G(he NORM r)-2.5 E(eceiver)-.18 E(constr)93.6 228 Q(ucts r)-.08 E
(epair r)-.18 E(equests with)-.18 E/F2 10/Courier@0 SF(NORM_NACK_BLOCK)
2.5 E F0(or)2.5 E F2(NORM_NACK_OBJECT)2.5 E F0(flags set as)2.5 E(appr)
93.6 240 Q 2.5(opriate. The)-.18 F -.18(re)2.5 G(quest for r).18 E
(etransmission of)-.18 E F2(NORM_INFO)2.5 E F0
(is accomplished by setting the)2.5 E F2(NORM_NACK_INFO)93.6 252 Q F0
(flag in a corr)2.5 E(esponding r)-.18 E(epair r)-.18 E(equest.)-.18 E
/F3 10/Palatino-Bold@0 SF(5.4.)72 276 Q/F4 12/Palatino-Bold@0 SF
(Sender NACK Processing and Response)5 E F0
(The principle goal of the sender is to make forwar)93.6 291.6 Q 2.5(dp)
-.18 G -.18(ro)-2.5 G(gr).18 E(ess in the transmission of data its)-.18
E(application has enqueued.)93.6 303.6 Q(However)5 E 2.5(,t)-.74 G
(he sender must occasionally "r)-2.5 E(ewind" its logical)-.18 E
(transmission point to satisfy the r)93.6 315.6 Q(epair needs of r)-.18
E(eceivers who have NACKed.)-.18 E(Aggr)5 E(egation)-.18 E
(of multiple NACKs is used to determine an optimal r)93.6 327.6 Q
(epair strategy when a NACK event)-.18 E 2.5(occurs. Since)93.6 339.6 R
-.18(re)2.5 G(ceivers initiate the NACK pr).18 E
(ocess on coding block or object boundaries,)-.18 E(ther)93.6 351.6 Q
2.5(ei)-.18 G 2.5(ss)-2.5 G(ome loose degr)-2.5 E(ee of synchr)-.18 E
(onization of the r)-.18 E(epair pr)-.18 E(ocess even when r)-.18 E
(eceivers)-.18 E(experience uncorr)93.6 363.6 Q(elated data loss.)-.18 E
F3 2.5(5.4.1. Sender)72 387.6 R(Repair State Aggregation)2.5 E F0
(When a sender is in its normal state of transmitting new data and r)
93.6 403.2 Q(eceives a NACK, it begins)-.18 E 2.5(ap)93.6 415.2 S -.18
(ro)-2.5 G(cedur).18 E 2.5(et)-.18 G 2.5(oa)-2.5 G(ccumulate NACK r)-2.5
E(epair state fr)-.18 E(om)-.18 E F2(NORM_NACK)2.5 E F0(messages befor)
2.5 E 2.5(eb)-.18 G(eginning)-2.5 E -.18(re)93.6 427.2 S
(pair transmissions.).18 E(Note that this period of aggr)5 E(egating r)
-.18 E(epair state does _not_ interfer)-.18 E(e)-.18 E
(with its ongoing transmission of new data.)93.6 439.2 Q
(As described in [3], the period of time during which the sender aggr)
93.6 463.2 Q(egates)-.18 E F2(NORM_NACK)2.5 E F0(messages is equal to:)
93.6 475.2 Q F2(T_sndrAggregate = \(Ksender+1\)*GRTT)196.8 499.2 Q F0
(wher)93.6 523.2 Q 2.5(e")-.18 G F2(Ksender)-2.5 E F0 2.5("i)C 2.5(st)
-2.5 G(he same backof)-2.5 E 2.5(fs)-.18 G(caling value used by the r)
-2.5 E(eceivers, and "GR)-.18 E(TT" is the)-.37 E -1.76(sender 's)93.6
535.2 R(curr)2.5 E(ent estimate of the gr)-.18 E(oup's gr)-.18 E
(eatest r)-.18 E(ound-trip time.)-.18 E(Note that for NORM)5 E
(unicast sessions the ")93.6 547.2 Q F2(T_sndrAggregate)A F0 2.5("t)C
(ime can be set to ZERO since ther)-2.5 E 2.5(ei)-.18 G 2.5(so)-2.5 G
(nly one)-2.5 E -.18(re)93.6 559.2 S(ceiver).18 E 5(.S)-.74 G(imilarly)
-5 E 2.5(,t)-1.11 G(he ")-2.5 E F2(Ksender)A F0 2.5("v)C
(alue should be set to ZERO for NORM unicast sessions)-2.5 E
(to minimize r)93.6 571.2 Q(epair latency)-.18 E(.)-1.11 E
(When this period ends, the sender "r)93.6 595.2 Q
(ewinds" by incorporating the accumulated r)-.18 E(epair state)-.18 E
(into its pending transmission state and begins transmitting r)93.6
607.2 Q(epair messages.)-.18 E(After pending)5 E -.18(re)93.6 619.2 S
(pair transmissions ar).18 E 2.5(ec)-.18 G
(ompleted, the sender continues with new transmissions of any)-2.5 E
(enqueued data.)93.6 631.2 Q
(Also, at this point in time, the sender begins a "holdof)5 E
(f" timeout during)-.18 E(which time the sender constrains itself fr)
93.6 643.2 Q(om initiating a new r)-.18 E(epair aggr)-.18 E
(egation cycle, even if)-.18 E F2(NORM_NACK)93.6 655.2 Q F0
(messages arrive.)2.5 E
(As described in [3], the value of this sender "holdof)5 E(f" period)
-.18 E(is:)93.6 667.2 Q F2(T_sndrHoldoff = \(1*GRTT\))226.8 691.2 Q F0
(If additional)93.6 715.2 Q F2(NORM_NACK)2.5 E F0(messages ar)2.5 E 2.5
(er)-.18 G(eceived during this sender "holdof)-2.68 E(f" period, the)
-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(sender will immediately incorp\
orate these "late messages" into its pending transmission)93.6 120 Q
(state ONL)93.6 132 Q 2.5(Yi)-.92 G 2.5(ft)-2.5 G(he NACK content is or)
-2.5 E(dinally gr)-.18 E(eater than the sender)-.18 E('s curr).74 E
(ent transmission)-.18 E 2.5(position. This)93.6 144 R("holdof)2.5 E
(f" time allows worst case time for the sender to pr)-.18 E
(opagate its curr)-.18 E(ent)-.18 E
(transmission sequence position to the gr)93.6 156 Q
(oup, thus avoiding r)-.18 E(edundant r)-.18 E(epair transmissions.)-.18
E(After the holdof)93.6 168 Q 2.5(ft)-.18 G(imeout expir)-2.5 E
(es, a new NACK accumulation period can be begun \(upon)-.18 E
(arrival of a NACK\) in concert with the pending r)93.6 180 Q
(epair and new data transmission.)-.18 E(Recall)5 E(that r)93.6 192 Q
(eceivers ar)-.18 E 2.5(en)-.18 G(ot to initiate the NACK r)-2.5 E
(epair pr)-.18 E(ocess until the sender)-.18 E('s logical).74 E
(transmission position exceeds the lowest or)93.6 204 Q
(dinal position of their r)-.18 E(epair needs.)-.18 E -.55(Wi)5 G
(th the).55 E(new NACK aggr)93.6 216 Q(egation period, the sender r)-.18
E(epeats the same pr)-.18 E(ocess of incorporating)-.18 E(accumulated r)
93.6 228 Q(epair state into its transmission plan and subsequently "r)
-.18 E(ewinding" to)-.18 E(transmit the lowest or)93.6 240 Q(dinal r)
-.18 E(epair data when the aggr)-.18 E(egation period expir)-.18 E 2.5
(es. Again,)-.18 F(this is)2.5 E
(conducted in concert with ongoing new data and/or pending r)93.6 252 Q
(epair transmissions.)-.18 E/F1 10/Palatino-Bold@0 SF 2.5(5.4.2. Sender)
72 276 R(FEC Repair T)2.5 E(ransmission Strategy)-1.11 E F0(The NORM se\
nder should leverage transmission of FEC parity content for r)93.6 291.6
Q(epair to the)-.18 E(gr)93.6 303.6 Q(eatest extent possible.)-.18 E
(Recall that the r)5 E(eceivers use a strategy to r)-.18 E
(equest a lowest common)-.18 E(denominator of explicit r)93.6 315.6 Q
(epair \(including parity content\) in the formation of their)-.18 E/F2
10/Courier@0 SF(NORM_NACK)93.6 327.6 Q F0 2.5(messages. Befor)2.5 F 2.5
(ef)-.18 G(alling back to explicitly satisfying dif)-2.5 E(fer)-.18 E
(ent r)-.18 E(eceivers' r)-.18 E(epair)-.18 E
(needs, the sender can make use of the general erasur)93.6 339.6 Q
(e-filling capability of FEC-generated)-.18 E(parity segments.)93.6
351.6 Q(The sender can determine the maximum erasur)5 E 2.5(ef)-.18 G
(illing needs for)-2.5 E(individual FEC coding blocks fr)93.6 363.6 Q
(om the)-.18 E F2(NORM_NACK)2.5 E F0(messages r)2.5 E
(eceived during the r)-.18 E(epair)-.18 E(aggr)93.6 375.6 Q
(egation period.)-.18 E(Then, if the sender has a suf)5 E
(ficient number \(less than or equal to the)-.18 E(maximum erasur)93.6
387.6 Q 2.5(ec)-.18 G(ount\) of pr)-2.5 E
(eviously unsent parity segments available for the applicable)-.18 E(co\
ding blocks, the sender can transmit these in lieu of the specific pack\
ets the r)93.6 399.6 Q(eceiver set)-.18 E(has r)93.6 411.6 Q 2.5
(equested. Only)-.18 F(after exhausting its supply of "fr)2.5 E
(esh" \(unsent\) parity segments for a)-.18 E
(given coding block should the sender r)93.6 423.6 Q
(esort to explicit transmission of the r)-.18 E(eceiver set's)-.18 E
-.18(re)93.6 435.6 S(pair needs.).18 E(In general, if a suf)5 E
(ficiently powerful FEC code is used, the need for explicit)-.18 E -.18
(re)93.6 447.6 S(pair will be an exception, and the fulfillment of r).18
E(eliable multicast can be accomplished)-.18 E(quite ef)93.6 459.6 Q
(ficiently)-.18 E 5(.H)-1.11 G(owever)-5 E 2.5(,t)-.74 G
(he ability to r)-2.5 E(esort to explicit r)-.18 E(epair allows the pr)
-.18 E(otocol to be)-.18 E -.18(re)93.6 471.6 S
(liable under even very extr).18 E(eme cir)-.18 E(cumstances.)-.18 E F2
(NORM_DATA)93.6 495.6 Q F0(messages sent as r)2.5 E
(epair transmissions SHALL be flagged with the)-.18 E F2
(NORM_FLAG_REPAIR)93.6 507.6 Q F0 2.5(flag. This)2.5 F(allows r)2.5 E
(eceivers to obey any policies that limit new)-.18 E -.18(re)93.6 519.6
S(ceivers fr).18 E(om joining the r)-.18 E
(eliable transmission when only r)-.18 E(epair transmissions have been)
-.18 E -.18(re)93.6 531.6 S 2.5(ceived. Additionally).18 F 2.5(,t)-1.11
G(he sender SHOULD additionally flag)-2.5 E F2(NORM_DATA)2.5 E F0
(transmissions)2.5 E(sent as explicit r)93.6 543.6 Q(epair with the)-.18
E F2(NORM_FLAG_EXPLICIT)2.5 E F0(flag.)2.5 E(Although NORM end system r)
93.6 567.6 Q(eceivers do not make use of the)-.18 E F2
(NORM_FLAG_EXPLICIT)2.5 E F0(flag,)2.5 E(this message transmission stat\
us could be leveraged by intermediate systems wishing to)93.6 579.6 Q
("assist" NORM pr)93.6 591.6 Q(otocol performance.)-.18 E
(If such systems ar)5 E 2.5(ep)-.18 G -.18(ro)-2.5 G
(perly positioned with r).18 E(espect)-.18 E(to r)93.6 603.6 Q(ecipr)
-.18 E(ocal r)-.18 E(everse-path multicast r)-.18 E
(outing, they need to sub-cast only a suf)-.18 E(ficient count of)-.18 E
(non-explicit parity r)93.6 615.6 Q(epairs to satisfy a multicast r)-.18
E(outing sub-tr)-.18 E(ee's erasur)-.18 E 2.5(ef)-.18 G
(illing needs for a)-2.5 E(given FEC coding block.)93.6 627.6 Q
(When the sender has r)5 E(esorted to explicit r)-.18 E(epair)-.18 E 2.5
(,t)-.74 G(hen the)-2.5 E
(intermediate systems should sub-cast all of the explicit r)93.6 639.6 Q
(epair packets to those portions of)-.18 E(the r)93.6 651.6 Q(outing tr)
-.18 E(ee still r)-.18 E(equiring r)-.18 E
(epair for a given coding block.)-.18 E(Note the intermediate)5 E
(systems will be r)93.6 663.6 Q(equir)-.18 E(ed to conduct r)-.18 E
(epair state accumulation for sub-r)-.18 E(outes in a manner)-.18 E
(similar to the sender)93.6 675.6 Q('s r).74 E
(epair state accumulation in or)-.18 E(der to have suf)-.18 E
(ficient information to)-.18 E(perform the sub-casting.)93.6 687.6 Q
(Additionally)5 E 2.5(,t)-1.11 G
(he intermediate systems could perform additional)-2.5 E F2(NORM_NACK)
93.6 699.6 Q F0(suppr)2.5 E(ession/aggr)-.18 E
(egation as it conducts this r)-.18 E(epair state accumulation for)-.18
E(NORM r)93.6 711.6 Q(epair cycles.)-.18 E
(The detail of this type of operation ar)5 E 2.5(eb)-.18 G
(eyond the scope of this)-2.5 E(document, but this information is pr)
93.6 723.6 Q(ovided for possible futur)-.18 E 2.5(ec)-.18 G
(onsideration.)-2.5 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Palatino-Bold@0 SF 2.5
(5.4.3. Sender)72 120 R(NORM_CMD\(SQUELCH\) Generation)2.5 E F0
(If the sender r)93.6 135.6 Q(eceives a)-.18 E/F2 10/Courier@0 SF
(NORM_NACK)2.5 E F0(message for r)2.5 E
(epair of data it is no longer supporting, the)-.18 E
(sender generates a)93.6 147.6 Q F2(NORM_CMD\(SQUELCH\))2.5 E F0
(message to advertise its r)2.5 E(epair window and)-.18 E(squelch any r)
93.6 159.6 Q(eceivers fr)-.18 E(om additional NACKing of invalid data.)
-.18 E(The transmission rate of)5 E F2(NORM_CMD\(SQUELCH\))93.6 171.6 Q
F0(messages is limited to once per)2.5 E F2(2*GRTT)2.5 E F0 5(.T)C
(he "invalid_object_list" \(if)-5 E(applicable\) of the)93.6 183.6 Q F2
(NORM_CMD\(SQUELCH\))2.5 E F0(message SHALL begin with the lowest)2.5 E
("object_transport_id" fr)93.6 195.6 Q(om the invalid)-.18 E F2
(NORM_NACK)2.5 E F0(messages r)2.5 E(eceived since the last)-.18 E F2
(NORM_CMD\(SQUELCH\))93.6 207.6 Q F0 2.5(transmission. Lower)2.5 F(or)
2.5 E(dinal invalid "object_transport_ids" should)-.18 E
(be included only while the)93.6 219.6 Q F2(NORM_CMD\(SQUELCH\))2.5 E F0
(payload is less than the sender)2.5 E('s).74 E/F3 10/Palatino-Italic@0
SF(NormSegmentSize)93.6 231.6 Q F0(parameter)2.5 E(.)-.74 E F1 2.5
(5.4.4. Sender)72 255.6 R(NORM_CMD\(REP)2.5 E(AIR_ADV\) Generation)-.74
E F0(When a NORM sender r)93.6 271.2 Q(eceives)-.18 E F2(NORM_NACK)2.5 E
F0(messages fr)2.5 E(om r)-.18 E(eceivers via unicast)-.18 E
(transmission, it uses)93.6 283.2 Q F2(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(messages to advertise its accumulated)2.5 E -.18(re)93.6 295.2 S
(pair state to the r).18 E(eceiver set since the r)-.18 E
(eceiver set is not dir)-.18 E(ectly sharing their r)-.18 E(epair needs)
-.18 E(via multicast communication.)93.6 307.2 Q 2.5(AN)5 G
(ORM sender implementation MA)-2.5 E 2.5(Yu)-1.11 G(se a separate port)
-2.5 E(number fr)93.6 319.2 Q(om the)-.18 E F3(NormSession)2.5 E F0
(port number as the sour)2.5 E(ce port for its transmissions.)-.18 E
(Thus)5 E(NORM r)93.6 331.2 Q(eceivers can dir)-.18 E
(ect any _unicast_ feedback messages to this sender port number that)
-.18 E(is distinct fr)93.6 343.2 Q(om the "session" port number)-.18 E 5
(.T)-.74 G(hen, the NORM sender implementation can)-5 E
(discriminate unicast feedback messages fr)93.6 355.2 Q
(om multicast feedback messages when ther)-.18 E 2.5(ei)-.18 G 2.5(sa)
-2.5 G(mix of multicast and unicast feedback r)93.6 367.2 Q 2.5
(eceivers. The)-.18 F F2(NORM_CMD\(REPAIR_ADV\))2.5 E F0(message is)2.5
E(multicast to the r)93.6 379.2 Q(eceiver set by the sender)-.18 E 5(.T)
-.74 G(he payload portion of this message has content)-5 E
(in the same format as the)93.6 391.2 Q F2(NORM_NACK)2.5 E F0 -.18(re)
2.5 G(ceiver message payload.).18 E(Receivers ar)5 E 2.5(et)-.18 G
(hen able to)-2.5 E(perform feedback suppr)93.6 403.2 Q
(ession in the same manner as with)-.18 E F2(NORM_NACK)2.5 E F0
(messages dir)2.5 E(ectly)-.18 E -.18(re)93.6 415.2 S(ceived fr).18 E
(om other r)-.18 E 2.5(eceivers. Note)-.18 F(the sender does not mer)2.5
E(ely r)-.18 E(etransmit NACK content it)-.18 E -.18(re)93.6 427.2 S
(ceives, but instead transmits a r).18 E(epr)-.18 E
(esentation of its aggr)-.18 E(egated r)-.18 E(epair state.)-.18 E(The)5
E(transmission of)93.6 439.2 Q F2(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(messages ar)2.5 E 2.5(es)-.18 G(ubject to the sender transmit rate)-2.5
E(limit and)93.6 451.2 Q F3(NormSegmentSize)2.5 E F0 2.5
(limitation. When)2.5 F(the)2.5 E F2(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(message is of)2.5 E(maximum size, r)93.6 463.2 Q
(eceivers SHALL consider the maximum or)-.18 E
(dinal transmission position value)-.18 E
(embedded in the message as the senders "curr)93.6 475.2 Q
(ent" transmission position and implicitly)-.18 E(suppr)93.6 487.2 Q
(ess r)-.18 E(equests for or)-.18 E(dinally higher r)-.18 E(epair)-.18 E
5(.F)-.74 G(or congestion contr)-5 E(ol operation, the sender)-.18 E
(may also need to pr)93.6 499.2 Q
(ovide information so that dynamic congestion contr)-.18 E
(ol feedback can be)-.18 E(suppr)93.6 511.2 Q(essed as needed among r)
-.18 E 2.5(eceivers. This)-.18 F
(document specifies the NORM-CC Feedback)2.5 E
(Header Extension that is applied for baseline NORM-CC operation.)93.6
523.2 Q(If other congestion)5 E(contr)93.6 535.2 Q(ol mechanisms ar)-.18
E 2.5(eu)-.18 G
(sed within a NORM implementation, other header extensions may)-2.5 E
(be defined.)93.6 547.2 Q
(Whatever content format is used for this purpose should ensur)5 E 2.5
(et)-.18 G(hat maximum)-2.5 E(possible suppr)93.6 559.2 Q
(ession state is conveyed to the r)-.18 E(eceiver set.)-.18 E F1(5.5.)72
583.2 Q/F4 12/Palatino-Bold@0 SF(Additional Protocol Mechanisms)5 E F0(\
In addition to the principal function of data content transmission and \
r)93.6 598.8 Q(epair)-.18 E 2.5(,t)-.74 G(her)-2.5 E 2.5(ea)-.18 G .36
-.18(re s)-2.5 H(ome).18 E(other pr)93.6 610.8 Q(otocol mechanisms that\
 help NORM to adapt to network conditions and play fairly)-.18 E
(with other coexistent pr)93.6 622.8 Q(otocols.)-.18 E F1 2.5
(5.5.1. Greatest)72 646.8 R(Round-trip T)2.5 E(ime Collection)-.55 E F0
(For NORM r)93.6 662.4 Q(eceivers to appr)-.18 E(opriately scale backof)
-.18 E 2.5(ft)-.18 G(imeouts and the senders to use pr)-2.5 E(oper)-.18
E(corr)93.6 674.4 Q(esponding timeouts, the participants must agr)-.18 E
(ee on a common timeout basis.)-.18 E(Each)5 E
(NORM sender monitors the r)93.6 686.4 Q(ound-trip time of active r)-.18
E(eceivers and determines the gr)-.18 E(oup)-.18 E(gr)93.6 698.4 Q
(eatest r)-.18 E(ound-trip time \(GR)-.18 E 2.5(TT\). The)-.37 F
(sender advertises this GR)2.5 E(TT estimate in every)-.37 E
(message it transmits so that r)93.6 710.4 Q
(eceivers have this value available for scaling their timers.)-.18 E
-.92(To)5 G(measur)93.6 722.4 Q 2.5(et)-.18 G(he curr)-2.5 E(ent GR)-.18
E(TT)-.37 E 2.5(,t)-.74 G(he sender periodically sends)-2.5 E F2
(NORM_CMD\(CC\))2.5 E F0(messages that)2.5 E(Adamson, et al.)72 768 Q
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(contain a locally generated timestamp.)93.6 120 Q(Receivers ar)5 E 2.5
(ee)-.18 G(xpected to r)-2.5 E(ecor)-.18 E 2.5(dt)-.18 G(his timestamp)
-2.5 E(along with the time the)93.6 132 Q/F1 10/Courier@0 SF
(NORM_CMD\(CC\))2.5 E F0(message is r)2.5 E 2.5(eceived. Then,)-.18 F
(when the r)2.5 E(eceivers)-.18 E
(generate feedback messages to the sender)93.6 144 Q 2.5(,a)-.74 G 2.5
(na)-2.5 G(djusted version of the sender timestamp is)-2.5 E
(embedded in the feedback message \()93.6 156 Q F1(NORM_NACK)A F0(or)2.5
E F1(NORM_ACK)2.5 E F0 2.5(\). The)B(adjustment adds the)2.5 E
(amount of time the r)93.6 168 Q(eceiver held the timestamp befor)-.18 E
2.5(eg)-.18 G(enerating its r)-2.5 E 2.5(esponse. Upon)-.18 F -.18(re)
2.5 G(ceipt).18 E
(of this adjusted timestamp, the sender is able to calculate the r)93.6
180 Q(ound-trip time to that r)-.18 E(eceiver)-.18 E(.)-.74 E(The r)93.6
204 Q(ound-trip time for each r)-.18 E
(eceiver is fed into an algorithm that weights and smoothes the)-.18 E
(values for a conservative estimate of the GR)93.6 216 Q(TT)-.37 E 5(.T)
-.74 G(he algorithm and methodology ar)-5 E(e)-.18 E(described in the N\
ORM Building Block document [3] in the section entitled "One-to-Many)
93.6 228 Q(Sender GR)93.6 240 Q(TT Measur)-.37 E 2.5(ement". A)-.18 F
(conservative estimate helps feedback suppr)2.5 E(ession at a small)-.18
E(cost in overall pr)93.6 252 Q(otocol r)-.18 E(epair delay)-.18 E 5(.T)
-1.11 G(he sender)-5 E('s curr).74 E(ent estimate of GR)-.18 E
(TT is advertised in)-.37 E
(the "grtt" field found in all NORM sender messages.)93.6 264 Q
(The advertised GR)5 E(TT is also limited to)-.37 E 2.5(am)93.6 276 S
(inimum of the nominal inter)-2.5 E
(-packet transmission time given the sender)-.18 E('s curr).74 E(ent)
-.18 E(transmission rate and system clock granularity)93.6 288 Q 5(.T)
-1.11 G(he r)-5 E(eason for this additional limit is to)-.18 E
(keep the r)93.6 300 Q(eceiver somewhat "event driven" by making sur)
-.18 E 2.5(et)-.18 G(he sender has had adequate)-2.5 E
(time to generate any r)93.6 312 Q(esponse to r)-.18 E(epair r)-.18 E
(equests fr)-.18 E(om r)-.18 E(eceivers given transmit rate)-.18 E
(limitations due to congestion contr)93.6 324 Q(ol or configuration.)
-.18 E(When the NORM-CC Rate header extension is pr)93.6 348 Q(esent in)
-.18 E F1(NORM_CMD\(CC\))2.5 E F0(messages, the)2.5 E -.18(re)93.6 360 S
(ceivers r).18 E(espond to)-.18 E F1(NORM_CMD\(CC\))2.5 E F0
(messages as described in Section 5.5.2, "NORM)2.5 E(Congestion Contr)
93.6 372 Q(ol Operation".)-.18 E(The)5 E F1(NORM_CMD\(CC\))2.5 E F0
(messages ar)2.5 E 2.5(ep)-.18 G(eriodically generated)-2.5 E
(by the sender as described for congestion contr)93.6 384 Q
(ol operation.)-.18 E(This pr)5 E(ovides for pr)-.18 E(oactive, but)-.18
E(contr)93.6 396 Q(olled, feedback fr)-.18 E(om the gr)-.18 E
(oup in the form of)-.18 E F1(NORM_ACK)2.5 E F0 2.5(messages. This)2.5 F
(pr)2.5 E(ovides for)-.18 E(GR)93.6 408 Q(TT feedback even if no)-.37 E
F1(NORM_NACK)2.5 E F0(messages ar)2.5 E 2.5(eb)-.18 G(eing sent.)-2.5 E
(If operating without)5 E(congestion contr)93.6 420 Q
(ol in a closed network, the)-.18 E F1(NORM_CMD\(CC\))2.5 E F0
(messages may be sent)2.5 E
(periodically without the NORM-CC Rate header extension.)93.6 432 Q
(In this case, r)5 E(eceivers will only)-.18 E(pr)93.6 444 Q(ovide GR)
-.18 E(TT measur)-.37 E(ement feedback when)-.18 E F1(NORM_NACK)2.5 E F0
(messages ar)2.5 E 2.5(eg)-.18 G(enerated since no)-2.5 E F1(NORM_ACK)
93.6 456 Q F0(messages ar)2.5 E 2.5(eg)-.18 G 2.5(enerated. In)-2.5 F
(this case, the)2.5 E F1(NORM_CMD\(CC\))2.5 E F0(messages may be sent)
2.5 E(less fr)93.6 468 Q(equently)-.18 E 2.5(,p)-1.11 G(er)-2.5 E
(haps as little as once per minute, to conserve network capacity)-.18 E
5(.N)-1.11 G(ote that)-5 E
(the NORM-CC Rate header extension may also be used pr)93.6 480 Q
(oactively solicit R)-.18 E(TT feedback)-.37 E(fr)93.6 492 Q(om the r)
-.18 E(eceiver gr)-.18 E(oup per congestion contr)-.18 E
(ol operation even though the sender may not be)-.18 E
(conducting congestion contr)93.6 504 Q(ol rate adjustment.)-.18 E
(NORM operation without congestion)5 E(contr)93.6 516 Q
(ol should be consider)-.18 E(ed only in closed networks.)-.18 E/F2 10
/Palatino-Bold@0 SF 2.5(5.5.2. NORM)72 540 R
(Congestion Control Operation)2.5 E F0
(This section describes baseline congestion contr)93.6 555.6 Q
(ol operation for the NORM pr)-.18 E(otocol)-.18 E 2.5(\(NORM-CC\). The)
93.6 567.6 R(supporting NORM message formats and appr)2.5 E
(oach described her)-.18 E 2.5(ea)-.18 G .36 -.18(re a)-2.5 H(n).18 E(a\
daptation of the equation-based TCP-Friendly Multicast Congestion Contr)
93.6 579.6 Q(ol \(TFMCC\))-.18 E(appr)93.6 591.6 Q
(oach described in [5].)-.18 E(This congestion contr)5 E
(ol scheme is REQUIRED for operation)-.18 E(within the general Internet\
 unless the NORM implementation is adapted to use another)93.6 603.6 Q
(IETF-sanctioned r)93.6 615.6 Q(eliable multicast congestion contr)-.18
E(ol mechanism \(e.g., PGMCC [26]\).)-.18 E -.55(Wi)5 G(th).55 E
(this TFMCC-based appr)93.6 627.6 Q
(oach, the transmissions of NORM senders ar)-.18 E 2.5(ec)-.18 G(ontr)
-2.5 E(olled in a rate-)-.18 E
(based manner as opposed to window-based congestion contr)93.6 639.6 Q
(ol algorithms as in TCP)-.18 E(.)-1.29 E(However)93.6 651.6 Q 2.5(,i)
-.74 G 2.5(ti)-2.5 G 2.5(sp)-2.5 G(ossible that the NORM pr)-2.5 E
(otocol message set may alternatively be used to)-.18 E
(support a window-based multicast congestion contr)93.6 663.6 Q
(ol scheme such as PGMCC.)-.18 E(The details)5 E
(of that alternative may be described separately or in a futur)93.6
675.6 Q 2.5(er)-.18 G(evision of this document.)-2.68 E(In)5 E(either c\
ase \(rate-based TFMCC or window-based PGMCC\), successful contr)93.6
687.6 Q(ol of sender)-.18 E
(transmission depends upon collection of sender)93.6 699.6 Q(-to-r)-.18
E(eceiver packet loss estimates and R)-.18 E(TT)-.37 E(s)-.9 E
(to identify the congestion contr)93.6 711.6 Q
(ol bottleneck path\(s\) within the multicast topology and adjust)-.18 E
(the sender rate accor)93.6 723.6 Q(dingly)-.18 E 5(.T)-1.11 G(he r)-5 E
(eceiver with loss and R)-.18 E(TT estimates that corr)-.37 E
(espond to the)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(lowest r)93.6 120 Q
(esulting calculated transmission rate is identified as the "curr)-.18 E
(ent limiting r)-.18 E(eceiver")-.18 E 2.5(\(CLR\). In)93.6 132 R
(the case of a "tie" \(wher)2.5 E 2.5(ec)-.18 G(andidate CLRs ar)-2.5 E
2.5(ew)-.18 G(ithin 10% of the same calculated)-2.5 E(rate\), the r)93.6
144 Q(eceiver with the lar)-.18 E(gest R)-.18 E
(TT value SHOULD be designated as the CLR.)-.37 E(As described in [27],)
93.6 168 Q 2.5(as)5 G
(teady-state sender transmission rate, to be "friendly" with)-2.5 E
(competing TCP flows can be calculated as:)93.6 180 Q/F1 10/Courier@0 SF
(S)306 204 Q(Rsender = ------------------------------------------------\
--------------)72 216 Q(tRTT*\(sqrt\(\(2/3\)*p\) + 12 * sqrt\(\(3/8\)*p\
\) * p * \(1 + 32*\(p^2\)\)\))132 228 Q F0(wher)93.6 252 Q(e)-.18 E F1
(S)111.6 282 Q F0(=)2.5 E(Nominal transmitted packet size. \(In NORM, t\
he "nominal" packet size can be determined by the)131.16 282 Q(sender a\
s an exponentially weighted moving average \(EWMA\) of transmitted pack\
et sizes to)131.16 294 Q(account for variable message sizes\).)131.16
306 Q F1(tRTT)93.6 330 Q F0(=)2.5 E(The R)131.16 330 Q
(TT estimate of the curr)-.37 E(ent "curr)-.18 E(ent limiting r)-.18 E
(eceiver" \(CLR\).)-.18 E F1(p)111.6 354 Q F0(=)2.5 E
(The loss event fraction of the CLR.)131.16 354 Q 1.84 -.92(To s)93.6
387.6 T(upport congestion contr).92 E
(ol feedback collection and operation, the NORM sender)-.18 E
(periodically transmits)93.6 399.6 Q F1(NORM_CMD\(CC\))2.5 E F0
(command messages.)2.5 E(NORM_CMD\(CC\) messages)5 E(ar)93.6 411.6 Q 2.5
(em)-.18 G(ultiplexed with NORM data and r)-2.5 E
(epair transmissions and serve several purposes:)-.18 E(1\))93.6 441.6 Q
(Stimulate explicit feedback fr)106.93 441.6 Q(om the general r)-.18 E
(eceiver set to collect congestion contr)-.18 E(ol information.)-.18 E
(2\))93.6 465.6 Q(Communicate state to the r)106.93 465.6 Q
(eceiver set on the sender)-.18 E('s curr).74 E(ent congestion contr)
-.18 E(ol status including)-.18 E(details of the CLR.)106.93 477.6 Q
(3\))93.6 501.6 Q(Initiate rapid \(immediate\) feedback fr)106.93 501.6
Q(om the CLR in or)-.18 E(der to closely track the dynamics of)-.18 E
(congestion contr)106.93 513.6 Q(ol for that curr)-.18 E
(ent "worst path" in the gr)-.18 E(oup multicast topology)-.18 E(.)-1.11
E(The format of the)93.6 543.6 Q F1(NORM_CMD\(CC\))2.5 E F0
(message is describe in Section 4.2.3 of this document.)2.5 E(The)5 E F1
(NORM_CMD\(CC\))93.6 555.6 Q F0
(message contains information to allow measur)2.5 E(ement of R)-.18 E
(TT)-.37 E(s, to inform the)-.9 E(gr)93.6 567.6 Q
(oup of the congestion contr)-.18 E(ol CLR, and to pr)-.18 E
(ovide feedback of individual R)-.18 E(TT)-.37 E(measur)93.6 579.6 Q
(ements to the r)-.18 E(eceivers in the gr)-.18 E 2.5(oup. The)-.18 F F1
(NORM_CMD\(CC\))2.5 E F0(also pr)2.5 E(ovides for exciting)-.18 E
(feedback fr)93.6 591.6 Q(om OPTIONAL "potential limiting r)-.18 E
(eceiver" \(PLR\) nodes that may be determined)-.18 E
(administratively or possibly algorithmically based on congestion contr)
93.6 603.6 Q(ol feedback.)-.18 E(PLR)5 E(nodes ar)93.6 615.6 Q 2.5(er)
-.18 G(eceivers that have been identified to have potential for \(per)
-2.68 E(haps soon\) becoming)-.18 E(the CLR and thus immediate, up-to-d\
ate feedback is beneficial for congestion contr)93.6 627.6 Q(ol)-.18 E
2.5(performance. The)93.6 639.6 R(details of PLR selection ar)2.5 E 2.5
(en)-.18 G(ot discussed in this document.)-2.5 E/F2 10/Palatino-Bold@0
SF 2.5(5.5.2.1. NORM_CMD\(CC\))72 675.6 R -1.11(Tr)2.5 G(ansmission)1.11
E F0(The)93.6 691.2 Q F1(NORM_CMD\(CC\))2.5 E F0(message is transmitted\
 periodically by the sender along with its normal)2.5 E
(data transmission.)93.6 703.2 Q(Note that the r)5 E
(epeated transmission of)-.18 E F1(NORM_CMD\(CC\))2.5 E F0
(messages may be)2.5 E(initiated some time befor)93.6 715.2 Q 2.5(et)
-.18 G(ransmission of user data content at session startup.)-2.5 E
(This may be)5 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(done to collect some estimation of the curr)93.6 120 Q
(ent state of the multicast topology with r)-.18 E(espect to)-.18 E(gr)
93.6 132 Q(oup and individual R)-.18 E(TT and congestion contr)-.37 E
(ol state.)-.18 E(A)93.6 156 Q/F1 10/Courier@0 SF(NORM_CMD\(CC\))2.5 E
F0(message is immediately transmitted at sender startup.)2.5 E
(The interval of)5 E(subsequent)93.6 168 Q F1(NORM_CMD\(CC\))2.5 E F0
(message transmission is determined as follows:)2.5 E(1\))93.6 198 Q
(By default, the interval is set accor)106.93 198 Q(ding to the curr)
-.18 E(ent sender GR)-.18 E(TT estimate.)-.37 E 2.5(As)5 G(tartup GR)
-2.5 E(TT of)-.37 E(0.5 seconds is r)106.93 210 Q
(ecommended when no feedback has yet been r)-.18 E(eceived fr)-.18 E
(om the gr)-.18 E(oup.)-.18 E(2\))93.6 234 Q
(Until a CLR has been identified \(based on pr)106.93 234 Q(evious r)
-.18 E(eceiver feedback\) or when no data)-.18 E
(transmission is pending, the)106.93 246 Q F1(NORM_CMD\(CC\))2.5 E F0
(interval is doubled up fr)2.5 E(om its curr)-.18 E(ent interval to a)
-.18 E(maximum of once per 30 seconds.)106.93 258 Q(This r)5 E
(esults in a low duty cycle for)-.18 E F1(NORM_CMD\(CC\))2.5 E F0(pr)2.5
E(obing)-.18 E(when no CLR is identified or ther)106.93 270 Q 2.5(ei)
-.18 G 2.5(sn)-2.5 G 2.5(op)-2.5 G(ending data to transmit.)-2.5 E
(T}.sp 3\))5 E(T{ When a CLR has)16.67 E(been identified \(based on r)
106.93 282 Q
(eceiver feedback\) and data transmission is pending, the pr)-.18 E
(obing)-.18 E(interval is set to the R)106.93 294 Q
(TT between the sender and the CLR \(R)-.37 E(TT_clr\).)-.37 E(4\))93.6
318 Q(Additionally)106.93 318 Q 2.5(,w)-1.11 G
(hen the data transmission rate is low with r)-2.5 E(espect to the R)
-.18 E(TT_clr interval used for)-.37 E(pr)106.93 330 Q
(obing, the implementation should ensur)-.18 E 2.5(et)-.18 G(hat no mor)
-2.5 E 2.5(et)-.18 G(han one)-2.5 E F1(NORM_CMD\(CC\))2.5 E F0
(message is)2.5 E(sent per NORM_DA)106.93 342 Q 1.48 -.74(TA m)-.74 H
(essage when ther).74 E 2.5(ei)-.18 G 2.5(sd)-2.5 G
(ata pending transmission.)-2.5 E(This ensur)5 E(es that the)-.18 E
(transmission of this contr)106.93 354 Q
(ol message is not done to the exclusion of user data transmission.)-.18
E(The)93.6 384 Q F1(NORM_CMD\(CC\))2.5 E F0("cc_sequence" field is incr)
2.5 E(emented with each transmission of a)-.18 E F1(NORM_CMD\(CC\))93.6
396 Q F0 2.5(command. The)2.5 F(gr)2.5 E(eatest "cc_sequence" r)-.18 E
(ecently r)-.18 E(eceived by r)-.18 E(eceivers is)-.18 E
(included in their feedback to the sender)93.6 408 Q 5(.T)-.74 G
(his allows the sender to determine the "age" of)-5 E
(feedback to assist in congestion avoidance.)93.6 420 Q
(The NORM-CC Rate Header Extension is applied to the)93.6 444 Q F1
(NORM_CMD\(CC\))2.5 E F0(message and the)2.5 E
(sender advertises its curr)93.6 456 Q
(ent transmission rate in the "send_rate" field.)-.18 E
(The rate information)5 E(is used by r)93.6 468 Q
(eceivers to initialize loss estimation during congestion contr)-.18 E
(ol startup or r)-.18 E(estart.)-.18 E
(The "cc_node_list" contains a list of entries identifying r)93.6 492 Q
(eceivers and their curr)-.18 E(ent congestion)-.18 E(contr)93.6 504 Q
(ol state \(status "flags", "rtt" and "loss" estimates\).)-.18 E
(The list may be empty if the sender)5 E(has not yet r)93.6 516 Q
(eceived any feedback fr)-.18 E(om the gr)-.18 E 2.5(oup. If)-.18 F
(the sender has r)2.5 E(eceived feedback, the)-.18 E
(list will minimally contain an entry identifying the CLR.)93.6 528 Q(A)
5 E F1(NORM_FLAG_CC_CLR)2.5 E F0(flag value)2.5 E(is pr)93.6 540 Q
(ovided for the "cc_flags" field to identify the CLR entry)-.18 E 5(.I)
-1.11 G 2.5(ti)-5 G 2.5(sR)-2.5 G(ECOMMENDED that the)-2.5 E
(CLR entry be the first in the list for implementation ef)93.6 552 Q
(ficiency)-.18 E 5(.A)-1.11 G(dditional entries in the list)-5 E(ar)93.6
564 Q 2.5(eu)-.18 G(sed to pr)-2.5 E(ovide sender)-.18 E(-measur)-.18 E
(ed individual R)-.18 E(TT estimates to r)-.37 E(eceivers in the gr)-.18
E(oup.)-.18 E(The number of additional entries in this list is dependen\
t upon the per)93.6 576 Q(centage of contr)-.18 E(ol)-.18 E(traf)93.6
588 Q(fic the sender application is willing to send with r)-.18 E
(espect to user data message)-.18 E 2.5(transmissions. Mor)93.6 600 R
2.5(ee)-.18 G(ntries in the list may allow the sender to be mor)-2.5 E
2.5(er)-.18 G(esponsive to)-2.68 E(congestion contr)93.6 612 Q
(ol dynamics.)-.18 E
(The length of the list may be dynamically determined)5 E(accor)93.6 624
Q(ding to the curr)-.18 E(ent transmission rate and scheduling of)-.18 E
F1(NORM_CMD\(CC\))2.5 E F0 2.5(messages. The)2.5 F
(maximum length of the list corr)93.6 636 Q(esponds to the sender)-.18 E
('s).74 E/F2 10/Palatino-Italic@0 SF(NormSegmentSize)2.5 E F0
(parameter for the)2.5 E 2.5(session. The)93.6 648 R
(inclusion of additional entries in the list based on r)2.5 E
(eceiver feedback ar)-.18 E(e)-.18 E(prioritized with following r)93.6
660 Q(ules:)-.08 E(1\))93.6 690 Q(Receivers that have not yet been pr)
106.93 690 Q(ovided a R)-.18 E(TT measur)-.37 E
(ement get first priority)-.18 E 5(.O)-1.11 G 2.5(ft)-5 G(hese, those)
-2.5 E(with the gr)106.93 702 Q(eatest loss fraction r)-.18 E(eceive pr)
-.18 E(ecedence for list inclusion.)-.18 E(Adamson, et al.)72 768 Q
(Expir)87.875 E(es: 31 December 2007)-.18 E([Page 55])116.525 E 0 Cg EP
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(2\))93.6 120 Q(Secondly)106.93
120 Q 2.5(,r)-1.11 G(eceivers that have pr)-2.68 E(eviously been pr)-.18
E(ovided a R)-.18 E(TT measur)-.37 E(ement ar)-.18 E 2.5(ei)-.18 G
(ncluded with)-2.5 E -.18(re)106.93 132 S
(ceivers yielding the lowest calculated congestion rate getting pr).18 E
(ecedence.)-.18 E(Ther)93.6 162 Q 2.5(ea)-.18 G .36 -.18(re ")-2.5 H
(cc_flag" values in addition to).18 E/F1 10/Courier@0 SF
(NORM_FLAG_CC_CLR)2.5 E F0(that ar)2.5 E 2.5(eu)-.18 G(sed for other)
-2.5 E(congestion contr)93.6 174 Q(ol functions.)-.18 E(The)5 E F1
(NORM_FLAG_CC_PLR)2.5 E F0(flag value is used to mark)2.5 E
(additional r)93.6 186 Q(eceivers fr)-.18 E
(om that the sender would like to have immediate, non-suppr)-.18 E
(essed)-.18 E 2.5(feedback. These)93.6 198 R(may be r)2.5 E
(eceivers that the sender algorithmically identified as potential)-.18 E
(futur)93.6 210 Q 2.5(eC)-.18 G(LRs or that have been pr)-2.5 E
(e-configur)-.18 E(ed as potential congestion contr)-.18 E
(ol points in the)-.18 E 2.5(network. The)93.6 222 R F1
(NORM_FLAG_CC_RTT)2.5 E F0
(indicates the validity of the "cc_rtt" field for the)2.5 E
(associated r)93.6 234 Q(eceiver node.)-.18 E(Normally)5 E 2.5(,t)-1.11
G(his flag will be set since the r)-2.5 E(eceivers in the list will)-.18
E(typically be r)93.6 246 Q(eceivers fr)-.18 E
(om which the sender has r)-.18 E(eceived feedback.)-.18 E(However)5 E
2.5(,i)-.74 G 2.5(nt)-2.5 G(he case)-2.5 E
(that the NORM sender has been pr)93.6 258 Q(e-configur)-.18 E
(ed with a set of PLR nodes, feedback fr)-.18 E(om)-.18 E(those r)93.6
270 Q(eceivers may not yet have been collected and thus the "cc_rtt" fi\
eld does not contain a)-.18 E(valid value when this flag is not set.)
93.6 282 Q(Similarly)5 E 2.5(,av)-1.11 G
(alue of ZERO for the "cc_rate" field her)-2.5 E(e)-.18 E(should be tr)
93.6 294 Q(eated as an invalid value and be ignor)-.18 E
(ed for the purposes of feedback)-.18 E(suppr)93.6 306 Q(ession, etc.)
-.18 E/F2 10/Palatino-Bold@0 SF 2.5(5.5.2.2. NORM_CMD\(CC\))72 342 R
(Feedback Response)2.5 E F0(Receivers explicitly r)93.6 357.6 Q
(espond to)-.18 E F1(NORM_CMD\(CC\))2.5 E F0(messages in the form of a)
2.5 E F1(NORM_ACK)2.5 E F0(\(R)A(TT\))-.37 E 2.5(message. The)93.6 369.6
R(goal of the congestion contr)2.5 E(ol feedback is to determine the r)
-.18 E(eceivers with the)-.18 E(lowest congestion contr)93.6 381.6 Q
(ol rates.)-.18 E(Receivers that ar)5 E 2.5(em)-.18 G
(arked as CLR or PLR nodes in the)-2.5 E F1(NORM_CMD\(CC\))93.6 393.6 Q
F0("cc_node_list" immediately pr)2.5 E(ovide feedback in the form of a)
-.18 E F1(NORM_ACK)2.5 E F0(to)2.5 E(this message.)93.6 405.6 Q(When a)5
E F1(NORM_CMD\(CC\))2.5 E F0(is r)2.5 E
(eceived, non-CLR or non-PLR nodes initiate)-.18 E
(random feedback backof)93.6 417.6 Q 2.5(ft)-.18 G
(imeouts similar to that used when the r)-2.5 E(eceiver initiates a r)
-.18 E(epair)-.18 E(cycle \(see Section 5.3\) in r)93.6 429.6 Q
(esponse to detection of data loss.)-.18 E(The backof)5 E 2.5(ft)-.18 G
(imeout for the)-2.5 E(congestion contr)93.6 441.6 Q(ol r)-.18 E
(esponse is generated as follows:)-.18 E F1
(T_backoff = RandomBackoff\(K*GRTTsender, GSIZEsender\))142.8 465.6 Q F0
(The ")93.6 489.6 Q F1(RandomBackoff\(\))A F0 2.5("a)C(lgorithm pr)-2.5
E(ovides a tr)-.18 E(uncated exponentially distributed random)-.08 E
(number and is described in the NORM Building Block document [3].)93.6
501.6 Q(The same backof)5 E(f)-.18 E(factor)93.6 513.6 Q F1 6(K=K)2.5 G
(sender)-6 E F0(MA)2.5 E 2.5(Yb)-1.11 G 2.5(eu)-2.5 G(sed as with)-2.5 E
F1(NORM_NACK)2.5 E F0(suppr)2.5 E 2.5(ession. However)-.18 F 2.5(,i)-.74
G 2.5(nc)-2.5 G(ases)-2.5 E(wher)93.6 525.6 Q 2.5(et)-.18 G
(he application purposefully specifies a very small)-2.5 E F1(Ksender)
2.5 E F0(backof)2.5 E 2.5(ff)-.18 G(actor to)-2.5 E(minimize the NACK r)
93.6 537.6 Q(epair pr)-.18 E(ocess latency \(trading of)-.18 E 2.5(fg)
-.18 G -.18(ro)-2.5 G(up size scalability\), it is).18 E
(RECOMMENDED that a lar)93.6 549.6 Q(ger backof)-.18 E 2.5(ff)-.18 G
(actor for congestion contr)-2.5 E(ol feedback is maintained,)-.18 E
(since ther)93.6 561.6 Q 2.5(em)-.18 G(ay often be a lar)-2.5 E
(ger volume of congestion contr)-.18 E(ol feedback than NACKs in)-.18 E
(many cases and some congestion contr)93.6 573.6 Q
(ol feedback latency may be tolerable wher)-.18 E 2.5(er)-.18 G(eliable)
-2.68 E(delivery latency is not.)93.6 585.6 Q(As pr)5 E
(eviously noted, a backof)-.18 E 2.5(ff)-.18 G(actor value of)-2.5 E F1
6(K=4)2.5 G F0(is generally)-3.5 E -.18(re)93.6 597.6 S
(commended for ASM operation and).18 E F1 6(K=6)2.5 G F0
(for SSM operation.)-3.5 E 2.5(Ar)5 G(eceiver SHALL cancel)-2.68 E
(the backof)93.6 609.6 Q 2.5(ft)-.18 G
(imeout and thus its pending transmission of a)-2.5 E F1(NORM_ACK)2.5 E
F0(\(R)A(TT\) message under)-.37 E(the following conditions:)93.6 621.6
Q(1\))93.6 663.6 Q(The r)106.93 663.6 Q
(eceiver generates another feedback message \()-.18 E F1(NORM_NACK)A F0
(or other)2.5 E F1(NORM_ACK)2.5 E F0 2.5(\)b)C(efor)-2.5 E 2.5(et)-.18 G
(he)-2.5 E(congestion contr)106.93 675.6 Q(ol feedback timeout expir)
-.18 E(es \(these messages will convey the curr)-.18 E(ent congestion)
-.18 E(contr)106.93 687.6 Q(ol feedback information\),)-.18 E
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(2\))93.6 120 Q(A)106.93 120 Q
/F1 10/Courier@0 SF(NORM_CMD\(CC\))2.5 E F0(or other r)2.5 E
(eceiver feedback with an or)-.18 E(dinally gr)-.18 E
(eater "cc_sequence" field value)-.18 E(is r)106.93 132 Q(eceived befor)
-.18 E 2.5(et)-.18 G(he congestion contr)-2.5 E
(ol feedback timeout expir)-.18 E(es \(this is similar to the TFMCC)-.18
E(feedback r)106.93 144 Q(ound number\),)-.18 E(3\))93.6 168 Q(When the)
106.93 168 Q F1(T_backoff)2.5 E F0(is gr)2.5 E(eater than)-.18 E F1
(1*GRTTsender)2.5 E F0 5(.T)C(his pr)-5 E(events NACK implosion in the)
-.18 E(event of sender or network failur)106.93 180 Q(e,)-.18 E(4\))93.6
204 Q("Suppr)106.93 204 Q(essing" congestion contr)-.18 E
(ol feedback is hear)-.18 E 2.5(df)-.18 G -.18(ro)-2.5 G 2.5(ma).18 G
(nother r)-2.5 E(eceiver \(in a)-.18 E F1(NORM_ACK)2.5 E F0(or)2.5 E F1
(NORM_NACK)106.93 216 Q F0 2.5(\)o)C 2.5(rv)-2.5 G(ia a)-2.5 E F1
(NORM_CMD\(REPAIR_ADV\))2.5 E F0(message fr)2.5 E(om the sender)-.18 E 5
(.T)-.74 G(he local r)-5 E -1.76(eceiver 's)-.18 F(feedback is "suppr)
106.93 228 Q
(essed" if the rate of the competing feedback \(Rfb\) is suf)-.18 E
(ficiently close to or less)-.18 E(than the local r)106.93 240 Q -1.76
(eceiver 's)-.18 F(calculated rate \(Rcalc\).)2.5 E(The local r)5 E
-1.76(eceiver 's)-.18 F(feedback is canceled when:)2.5 E F1
(Rcalc > \(0.9 * Rfb\))265.93 264 Q F0(Also note r)106.93 288 Q
(eceivers that have not yet r)-.18 E(eceived an R)-.18 E(TT measur)-.37
E(ement fr)-.18 E(om the sender ar)-.18 E(e)-.18 E(suppr)106.93 300 Q
(essed only by other r)-.18 E(eceivers that have not yet measur)-.18 E
(ed R)-.18 E(TT)-.37 E 5(.A)-.74 G(dditionally)-5 E 2.5(,r)-1.11 G
(eceivers)-2.68 E(whose R)106.93 312 Q(TT estimate has "aged" considera\
bly \(i.e., they haven't been included in the)-.37 E(NORM_CMD\(CC\) "cc\
_node_list" in a long time\) may wish to compete as a r)106.93 324 Q
(eceiver with no prior)-.18 E -.37(RT)106.93 336 S 2.5(Tm).37 G(easur)
-2.5 E(ement after some long term expiration period.)-.18 E
(When the backof)93.6 378 Q 2.5(ft)-.18 G(imer expir)-2.5 E(es, the r)
-.18 E(eceiver SHALL generate a)-.18 E F1(NORM_ACK\(RTT\))2.5 E F0
(message to)2.5 E(pr)93.6 390 Q(ovide feedback to the sender and gr)-.18
E 2.5(oup. This)-.18 F(message may be multicast to the gr)2.5 E(oup for)
-.18 E(most ef)93.6 402 Q(fective suppr)-.18 E
(ession in ASM topologies or unicast to the sender depending upon how)
-.18 E(the NORM pr)93.6 414 Q(otocol is deployed and configur)-.18 E
(ed.)-.18 E(Whenever any feedback is generated \(including this)93.6 438
Q F1(NORM_ACK\(RTT\))2.5 E F0(message\), r)2.5 E(eceivers)-.18 E
(include an adjusted version of the sender timestamp fr)93.6 450 Q
(om the most r)-.18 E(ecently r)-.18 E(eceived)-.18 E F1(NORM_CMD\(CC\))
93.6 462 Q F0(message and the "cc_sequence" value fr)2.5 E
(om that command in the applicable)-.18 E F1(NORM_ACK)93.6 474 Q F0(or)
2.5 E F1(NORM_NACK)2.5 E F0(message fields.)2.5 E
(For NORM-CC operation, any generated)5 E(feedback message SHALL also c\
ontain the NORM-CC Feedback header extension.)93.6 486 Q(The)5 E -.18
(re)93.6 498 S(ceiver pr).18 E(ovides its curr)-.18 E
(ent "cc_rate" estimate, "cc_loss" estimate, "cc_rtt" if known, and any)
-.18 E(applicable "cc_flags" via this header extension.)93.6 510 Q
(During)93.6 534 Q/F2 10/Palatino-Italic@0 SF(slow start)2.5 E F0
(\(when the r)2.5 E(eceiver has not yet detected loss fr)-.18 E
(om the sender\), the r)-.18 E(eceiver)-.18 E
(uses a value equal to two times its measur)93.6 546 Q(ed rate fr)-.18 E
(om the sender in the "cc_rate" field.)-.18 E(For)5 E
(steady-state congestion contr)93.6 558 Q(ol operation, the r)-.18 E
(eceiver "cc_rate" value is fr)-.18 E(om the equation-)-.18 E
(based value using its curr)93.6 570 Q
(ent loss event estimate and sender<->r)-.18 E(eceiver R)-.18 E
(TT information.)-.37 E(\(The GR)93.6 582 Q(TT is used when the r)-.37 E
(eceiver has not yet measur)-.18 E(ed its individual R)-.18 E(TT\).)-.37
E(The "cc_loss" field value r)93.6 606 Q(eflects the r)-.18 E -1.76
(eceiver 's)-.18 F(curr)2.5 E(ent loss event estimate with r)-.18 E
(espect to the)-.18 E(sender in question.)93.6 618 Q(When the r)93.6 642
Q(eceiver has a valid individual R)-.18 E(TT measur)-.37 E
(ement, it SHALL include this value in)-.18 E(the "cc_rtt" field.)93.6
654 Q(The)5 E F1(NORM_FLAG_CC_RTT)2.5 E F0
(MUST be set when the "cc_rtt" field is valid.)2.5 E
(After a congestion contr)93.6 678 Q
(ol feedback message is generated or when the feedback is)-.18 E(suppr)
93.6 690 Q(essed, a non-CLR r)-.18 E(eceiver begins a "holdof)-.18 E
(f" timeout period during which it will)-.18 E -.18(re)93.6 702 S
(strain itself fr).18 E(om pr)-.18 E(oviding congestion contr)-.18 E
(ol feedback, even if)-.18 E F1(NORM_CMD\(CC\))2.5 E F0(messages)2.5 E
(ar)93.6 714 Q 2.5(er)-.18 G(eceived fr)-2.68 E
(om the sender \(unless the r)-.18 E
(eceive becomes marked as a CLR or PLR node\).)-.18 E(Adamson, et al.)72
768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E([Page 57])116.525 E 0
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(The value of this holdof)93.6
120 Q 2.5(ft)-.18 G(imeout \()-2.5 E/F1 10/Courier@0 SF(T_ccHoldoff)A F0
2.5(\)p)C(eriod is:)-2.5 E F1(T_ccHoldoff = \(K*GRTT\))232.8 144 Q F0
(Thus, non-CLR r)93.6 168 Q(eceivers ar)-.18 E 2.5(ec)-.18 G
(onstrained to pr)-2.5 E(oviding explicit congestion contr)-.18 E
(ol feedback)-.18 E(once per)93.6 180 Q F1(K*GRTT)2.5 E F0 2.5
(intervals. Note,)2.5 F(however)2.5 E 2.5(,t)-.74 G
(hat as the session pr)-2.5 E(ogr)-.18 E(esses, dif)-.18 E(fer)-.18 E
(ent r)-.18 E(eceivers)-.18 E(will be r)93.6 192 Q(esponding to dif)-.18
E(fer)-.18 E(ent)-.18 E F1(NORM_CMD\(CC\))2.5 E F0(messages and ther)2.5
E 2.5(ew)-.18 G(ill be r)-2.5 E(elatively)-.18 E
(continuous feedback of congestion contr)93.6 204 Q
(ol information while the sender is active.)-.18 E/F2 10/Palatino-Bold@0
SF 2.5(5.5.2.3. Congestion)72 240 R(Control Rate Adjustment)2.5 E F0
(During steady-state operation, the sender will dir)93.6 255.6 Q
(ectly adjust its transmission rate to the rate)-.18 E
(indicated by the feedback fr)93.6 267.6 Q(om its curr)-.18 E
(ently selected CLR.)-.18 E(As noted in [24], the estimation of)5 E
(parameters \(loss and R)93.6 279.6 Q
(TT\) for the CLR will generally constrain the rate changes possible)
-.37 E(within acceptable bounds.)93.6 291.6 Q(For rate incr)5 E
(eases, the sender SHALL observe a maximum rate of)-.18 E(incr)93.6
303.6 Q(ease of one packet per R)-.18 E
(TT at all times during steady-state operation.)-.37 E(The sender pr)
93.6 327.6 Q(ocesses congestion contr)-.18 E(ol feedback fr)-.18 E
(om the r)-.18 E(eceivers and selects the CLR)-.18 E
(based on the lowest rate r)93.6 339.6 Q(eceiver)-.18 E 5(.R)-.74 G
(eceiver rates ar)-5 E 2.5(ee)-.18 G(ither determined dir)-2.5 E
(ectly fr)-.18 E(om the)-.18 E/F3 10/Palatino-Italic@0 SF(slow)2.5 E
(start)93.6 351.6 Q F0("cc_rate" pr)2.5 E(ovided by the r)-.18 E
(eceiver in the NORM-CC Feedback header extension or by)-.18 E
(performing the equation-based calculation using individual R)93.6 363.6
Q(TT and loss estimates)-.37 E(\("cc_loss"\) as feedback is r)93.6 375.6
Q(eceived.)-.18 E(The sender can calculate a curr)93.6 399.6 Q(ent R)
-.18 E(TT for a r)-.37 E(eceiver \()-.18 E F1(RTT_rcvrNew)A F0 2.5(\)u)C
(sing the)-2.5 E("grtt_r)93.6 411.6 Q
(esponse" timestamp included in feedback messages.)-.18 E
(When the "cc_rtt" value in a)5 E -.18(re)93.6 423.6 S
(sponse is not valid, the sender simply uses this).18 E F1(RTT_rcvrNew)
2.5 E F0(value as the r)2.5 E -1.76(eceiver 's)-.18 F(curr)93.6 435.6 Q
(ent R)-.18 E(TT \()-.37 E F1(RTT_rcvr)A F0 2.5(\). For)B
(non-CLR and non-PLR r)2.5 E(eceivers, the sender can use the)-.18 E
("cc_rtt" value pr)93.6 447.6 Q
(ovided in the NORM-CC Feedback header extension as the r)-.18 E -1.76
(eceiver 's)-.18 F(pr)93.6 459.6 Q(evious R)-.18 E(TT measur)-.37 E
(ement \()-.18 E F1(RTT_rcvrPrev)A F0 2.5(\)t)C 2.5(os)-2.5 G
(mooth accor)-2.5 E(ding to:)-.18 E F1
(RTT_rcvr = 0.5 * RTT_rcvrPrev + 0.5 * RTT_rcvrNew)151.8 483.6 Q F0
(For CLR r)93.6 507.6 Q(eceivers wher)-.18 E 2.5(ef)-.18 G(eedback is r)
-2.5 E(eceived mor)-.18 E 2.5(er)-.18 G(egularly)-2.68 E 2.5(,t)-1.11 G
(he sender SHOULD maintain)-2.5 E 2.5(am)93.6 519.6 S(or)-2.5 E 2.5(es)
-.18 G(moothed R)-2.5 E(TT estimate upon new feedback fr)-.37 E
(om the CLR wher)-.18 E(e:)-.18 E F1
(RTT_clr = 0.9 * RTT_clr + 0.1 * RTT_clrNew)172.8 543.6 Q F0(")93.6
567.6 Q F1(RTT_clrNew)A F0 2.5("i)C 2.5(st)-2.5 G(he new R)-2.5 E
(TT calculated fr)-.37 E(om the timestamp in the feedback message)-.18 E
-.18(re)93.6 579.6 S(ceived fr).18 E(om the CLR.)-.18 E(The)5 E F1
(RTT_clr)2.5 E F0(is initialized to)2.5 E F1(RTT_clrNew)2.5 E F0
(on the first feedback)2.5 E(message r)93.6 591.6 Q 2.5(eceived. Note)
-.18 F(that the same pr)2.5 E(ocedur)-.18 E 2.5(ei)-.18 G 2.5(so)-2.5 G
(bserved by the sender for PLR r)-2.5 E(eceivers)-.18 E
(and that if a PLR is "pr)93.6 603.6 Q
(omoted" to CLR status, the smoothed estimate can be continued.)-.18 E
(Ther)93.6 627.6 Q 2.5(ea)-.18 G .36 -.18(re s)-2.5 H(ome additional pe\
riods besides steady-state operation that need to be consider).18 E(ed)
-.18 E(in NORM-CC operation.)93.6 639.6 Q(These periods ar)5 E(e:)-.18 E
14.17(1\) during)97 667.2 R(session startup,)2.5 E 14.17(2\) when)97
682.8 R(no feedback is r)2.5 E(eceived fr)-.18 E(om the CLR, and)-.18 E
14.17(3\) when)97 698.4 R(the sender has a br)2.5 E
(eak in data transmission.)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(During session startup, the congestion contr)93.6 120 Q
(ol operation SHALL observe a "slow start")-.18 E(pr)93.6 132 Q(ocedur)
-.18 E 2.5(et)-.18 G 2.5(oq)-2.5 G(uickly appr)-2.5 E
(oach its fair bandwidth shar)-.18 E 2.5(e. An)-.18 F
(initial sender startup rate is)2.5 E(assumed wher)93.6 144 Q(e:)-.18 E
/F1 10/Courier@0 SF(Rinitial = MIN\(NormSegmentSize / GRTT, NormSegment\
Size\) bytes/second.)93.6 168 Q F0(The rate is incr)93.6 192 Q
(eased only when feedback is r)-.18 E(eceived fr)-.18 E(om the r)-.18 E
(eceiver set.)-.18 E(The "slow start")5 E(phase pr)93.6 204 Q
(oceeds until any r)-.18 E(eceiver pr)-.18 E
(ovides feedback indicating that loss has occurr)-.18 E 2.5(ed. Rate)
-.18 F(incr)93.6 216 Q(ease during)-.18 E/F2 10/Palatino-Italic@0 SF
(slow start)2.5 E F0(is applied as:)2.5 E F1(Rnew = Rrecv_min)250.8 240
Q F0(wher)93.6 264 Q 2.5(e")-.18 G F1(Rrecv_min)-2.5 E F0 2.5("i)C 2.5
(st)-2.5 G(he minimum r)-2.5 E(eported r)-.18 E
(eceiver rate in the "cc_rate" field of)-.18 E(congestion contr)93.6 276
Q(ol feedback messages r)-.18 E(eceived fr)-.18 E(om the gr)-.18 E 2.5
(oup. Note)-.18 F(that during "slow)2.5 E(start", r)93.6 288 Q
(eceivers use two times their measur)-.18 E(ed rate fr)-.18 E
(om the sender in the "cc_rate" field of)-.18 E(their feedback.)93.6 300
Q(Rate incr)5 E(ease adjustment is limited to once per GR)-.18 E
(TT during slow start.)-.37 E(If the CLR or any r)93.6 324 Q
(eceiver intends to leave the gr)-.18 E(oup, it will set the)-.18 E
(NORM_FLAG_CC_LEA)93.6 336 Q(VE in its congestion contr)-1.11 E
(ol feedback message as an indication that)-.18 E
(the sender should not select it as the CLR.)93.6 348 Q
(When the CLR changes to a lower rate r)5 E(eceiver)-.18 E(,)-.74 E
(the sender should immediately adjust to the new lower rate.)93.6 360 Q
(The sender is limited to)5 E(incr)93.6 372 Q
(easing its rate at one additional packet per R)-.18 E(TT towar)-.37 E
(ds any new)-.18 E 2.5(,h)-.92 G(igher CLR rate.)-2.5 E
(The sender should also track the "age" of the feedback it has r)93.6
396 Q(eceived fr)-.18 E(om the CLR by)-.18 E(comparing its curr)93.6 408
Q
(ent "cc_sequence" value \(Seq_sender\) to the last "cc_sequence" value)
-.18 E -.18(re)93.6 420 S(ceived fr).18 E(om the CLR \(Seq_clr\).)-.18 E
(As the "age" of the CLR feedback incr)5 E(eases with no new)-.18 E
(feedback, the sender SHALL begin r)93.6 432 Q
(educing its rate once per)-.18 E F1(RTT_clr)2.5 E F0(as a congestion)
2.5 E(avoidance measur)93.6 444 Q 2.5(e. The)-.18 F
(following algorithm is used to determine the decr)2.5 E(ease in sender)
-.18 E(rate \(Rsender bytes/sec\) as the CLR feedback, unexpectedly)93.6
456 Q 2.5(,e)-1.11 G(xcessively ages:)-2.5 E F1
(Age = Seq_sender - Seq_clr;)93.6 480 Q
(if \(Age > 4\) Rsender = Rsender * 0.5;)93.6 492 Q F0(This rate r)93.6
516 Q(eduction is limited to the lower bound on NORM transmission rate.)
-.18 E(After)5 E F1(NORM_ROBUST_FACTOR)93.6 528 Q F0(consecutive)2.5 E
F1(NORM_CMD\(CC\))2.5 E F0 -.18(ro)2.5 G(unds without any feedback fr)
.18 E(om the)-.18 E
(CLR, the sender SHOULD assume the CLR has left the gr)93.6 540 Q
(oup and pick the r)-.18 E(eceiver with the)-.18 E
(next lowest rate as the new CLR.)93.6 552 Q
(Note this assumes that the sender does not have explicit)5 E
(knowledge that the CLR intentionally left the gr)93.6 564 Q 2.5
(oup. If)-.18 F(no r)2.5 E(eceiver feedback is r)-.18 E(eceived, the)
-.18 E(sender MA)93.6 576 Q 2.5(Yw)-1.11 G
(ish to withhold further transmissions of)-2.5 E F1(NORM_DATA)2.5 E F0
(segments and maintain)2.5 E F1(NORM_CMD\(CC\))93.6 588 Q F0
(transmissions only until feedback is detected.)2.5 E
(After such a CLR timeout,)5 E
(the sender will be transmitting with a minimal rate and should r)93.6
600 Q(eturn to slow start as)-.18 E(described her)93.6 612 Q 2.5(ef)-.18
G(or a br)-2.5 E(eak in data transmission.)-.18 E
(When the sender has a br)93.6 636 Q
(eak in its data transmission, it can continue to pr)-.18 E(obe the gr)
-.18 E(oup with)-.18 E F1(NORM_CMD\(CC\))93.6 648 Q F0
(messages to maintain R)2.5 E(TT collection fr)-.37 E(om the gr)-.18 E
2.5(oup. This)-.18 F(will enable the)2.5 E
(sender to quickly determine an appr)93.6 660 Q
(opriate CLR upon data transmission r)-.18 E 2.5(estart. However)-.18 F
(,)-.74 E(the sender should exponentially r)93.6 672 Q(educe its tar)
-.18 E(get rate to be used for transmission r)-.18 E(estart as)-.18 E
(time since the br)93.6 684 Q(eak elapses.)-.18 E(The tar)5 E
(get rate SHOULD be r)-.18 E(ecalculated once per)-.18 E F1(RTT_clr)2.5
E F0(as:)2.5 E F1(Rsender = Rsender * 0.5;)226.8 708 Q F0
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(If the minimum NORM rate is r)
93.6 120 Q(eached, the sender should set the NORM_FLAG_ST)-.18 E(AR)-.74
E 2.5(Tf)-.37 G(lag)-2.5 E(in its)93.6 132 Q/F1 10/Courier@0 SF
(NORM_CMD\(CC\))2.5 E F0(messages upon r)2.5 E(estart and the gr)-.18 E
(oup should observer "slow start")-.18 E(congestion contr)93.6 144 Q
(ol pr)-.18 E(ocedur)-.18 E(es until any r)-.18 E
(eceiver experiences a new loss event.)-.18 E/F2 10/Palatino-Bold@0 SF
2.5(5.5.3. NORM)72 168 R(Positive Acknowledgment Procedure)2.5 E F0
(NORM pr)93.6 183.6 Q(ovides options for the sour)-.18 E
(ce application to r)-.18 E(equest positive acknowledgment)-.18 E
(\(ACK\) of)93.6 195.6 Q F1(NORM_CMD\(FLUSH\))2.5 E F0(and)2.5 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(messages fr)2.5 E(om members of the)-.18 E
(gr)93.6 207.6 Q 2.5(oup. Ther)-.18 F 2.5(ea)-.18 G .36 -.18(re s)-2.5 H
(ome specific acknowledgment r).18 E(equests defined for the NORM pr)
-.18 E(otocol)-.18 E(and a range of acknowledgment r)93.6 219.6 Q
(equest types that ar)-.18 E 2.5(el)-.18 G
(eft to be defined by the application.)-2.5 E(One pr)93.6 231.6 Q
(edefined acknowledgment type is the)-.18 E F1(NORM_ACK_FLUSH)2.5 E F0
2.5(type. This)2.5 F(acknowledgment is used to determine if r)93.6 243.6
Q(eceivers have achieved completion of r)-.18 E(eliable)-.18 E -.18(re)
93.6 255.6 S(ception up thr).18 E
(ough a specific logical transmission point with r)-.18 E
(espect to the sender)-.18 E('s).74 E(sequence of transmission.)93.6
267.6 Q(The)5 E F1(NORM_ACK_FLUSH)2.5 E F0
(acknowledgment may be used to assist in)2.5 E(application flow contr)
93.6 279.6 Q(ol when the sender has information on a portion of the r)
-.18 E(eceiver set.)-.18 E(Another pr)93.6 291.6 Q
(edefined acknowledgment type is)-.18 E F1(NORM_ACK\(CC\))2.5 E F0 2.5
(,w)C(hich is used to explicitly)-2.5 E(pr)93.6 303.6 Q
(ovide congestion contr)-.18 E(ol feedback in r)-.18 E(esponse to)-.18 E
F1(NORM_CMD\(CC\))2.5 E F0(messages transmitted)2.5 E
(by the sender for NORM-CC operation.)93.6 315.6 Q(Note the)5 E F1
(NORM_ACK\(CC\))2.5 E F0 -.18(re)2.5 G(sponse does NOT).18 E
(follow the positive acknowledgment pr)93.6 327.6 Q(ocedur)-.18 E 2.5
(ed)-.18 G(escribed her)-2.5 E 2.5(e. The)-.18 F F1(NORM_CMD\(ACK_REQ\))
2.5 E F0(and)93.6 339.6 Q F1(NORM_ACK)2.5 E F0(messages contain an "ack\
_type" field to identify the type of acknowledgment)2.5 E -.18(re)93.6
351.6 S(quested and pr).18 E 2.5(ovided. A)-.18 F
(range of "ack_type" values is pr)2.5 E(ovided for application-defined)
-.18 E 2.5(use. While)93.6 363.6 R(the application is r)2.5 E
(esponsible for initiating the acknowledgment r)-.18 E(equest and)-.18 E
(interpr)93.6 375.6 Q
(ets application-defined "ack_type" values, the acknowledgment pr)-.18 E
(ocedur)-.18 E 2.5(eS)-.18 G(HOULD)-2.5 E(be conducted within the pr)
93.6 387.6 Q(otocol implementation to take advantage of timing and)-.18
E(transmission scheduling information available to the NORM transport.)
93.6 399.6 Q(The NORM positive acknowledgment pr)93.6 423.6 Q(ocedur)
-.18 E 2.5(eu)-.18 G(ses polling by the sender to query the)-2.5 E -.18
(re)93.6 435.6 S(ceiver gr).18 E(oup for r)-.18 E 2.5(esponse. Note)-.18
F(this polling pr)2.5 E(ocedur)-.18 E 2.5(ei)-.18 G 2.5(sn)-2.5 G
(ot intended to scale to very)-2.5 E(lar)93.6 447.6 Q(ge r)-.18 E
(eceiver gr)-.18 E(oups, but could be used in lar)-.18 E(ge gr)-.18 E
(oup setting to query a critical subset of)-.18 E(the gr)93.6 459.6 Q
2.5(oup. Either)-.18 F(the)2.5 E F1(NORM_CMD\(ACK_REQ\))2.5 E F0 2.5(,o)
C 2.5(rw)-2.5 G(hen applicable, the)-2.5 E F1(NORM_CMD\(FLUSH\))2.5 E F0
(message is used for polling and contains a list of)93.6 471.6 Q/F3 10
/Palatino-Italic@0 SF(NormNodeIds)2.5 E F0(for r)2.5 E
(eceivers that should)-.18 E -.18(re)93.6 483.6 S(spond to the command.)
.18 E(The list of r)5 E(eceivers pr)-.18 E
(oviding acknowledgment is determined by)-.18 E(the sour)93.6 495.6 Q(c\
e application with "a priori" knowledge of participating nodes or via s\
ome other)-.18 E(application-level mechanism.)93.6 507.6 Q(The ACK pr)
93.6 531.6 Q(ocess is initiated by the sender that generates)-.18 E F1
(NORM_CMD\(FLUSH\))2.5 E F0(or)2.5 E F1(NORM_CMD\(ACK_REQ\))93.6 543.6 Q
F0(messages in periodic "r)2.5 E 2.5(ounds". For)-.18 F F1
(NORM_ACK_FLUSH)2.5 E F0 -.18(re)2.5 G(quests, the).18 E F1
(NORM_CMD\(FLUSH\))93.6 555.6 Q F0
(contain a "object_transport_id" and "fec_payload_id" denoting the)2.5 E
(watermark transmission point for which acknowledgment is r)93.6 567.6 Q
2.5(equested. This)-.18 F(watermark)2.5 E
(transmission point is "echoed" in the corr)93.6 579.6 Q
(esponding fields of the)-.18 E F1(NORM_ACK\(FLUSH\))2.5 E F0
(message sent by the r)93.6 591.6 Q(eceiver in r)-.18 E(esponse.)-.18 E
F1(NORM_CMD\(ACK_REQ\))5 E F0(messages contain an)2.5 E
("ack_id" field which is similarly "echoed" in r)93.6 603.6 Q
(esponse so that the sender may match the)-.18 E -.18(re)93.6 615.6 S
(sponse to the appr).18 E(opriate r)-.18 E(equest.)-.18 E(In r)93.6
639.6 Q(esponse to the)-.18 E F1(NORM_CMD\(ACK_REQ\))2.5 E F0 2.5(,t)C
(he listed r)-2.5 E(eceivers randomly spr)-.18 E(ead)-.18 E F1(NORM_ACK)
2.5 E F0(messages uniformly in time over a window of \(1*GR)93.6 651.6 Q
2.5(TT\). These)-.37 F F1(NORM_ACK)2.5 E F0(messages ar)2.5 E(e)-.18 E
(typically unicast to the sender)93.6 663.6 Q 5(.\()-.74 G(Note that)-5
E F1(NORM_ACK\(CC\))2.5 E F0(messages SHALL be multicast or)2.5 E
(unicast in the same manner as)93.6 675.6 Q F1(NORM_NACK)2.5 E F0
(messages\).)2.5 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(The ACK pr)93.6 120 Q
(ocess is self-limiting and avoids ACK implosion in that:)-.18 E 14.17
(1\) Only)97 135.6 R 2.5(as)2.5 G(ingle)-2.5 E/F1 10/Courier@0 SF
(NORM_CMD\(ACK_REQ\))2.5 E F0(message is generated once per \(2*GR)2.5 E
(TT\), and,)-.37 E 14.17(2\) The)97 151.2 R
(size of the "acking_node_list" of)2.5 E/F2 10/Palatino-Italic@0 SF
(NormNodeIds)2.5 E F0(fr)2.5 E(om which acknowledgment is)-.18 E -.18
(re)122 163.2 S(quested is limited to a maximum of the sender).18 E F2
(NormSegmentSize)2.5 E F0(setting per r)2.5 E(ound)-.18 E
(of the positive acknowledgment pr)122 175.2 Q(ocess.)-.18 E
(Because the size of the included list is limited to the sender)93.6
202.8 Q('s).74 E F2(NormSegmentSize)2.5 E F0(setting,)2.5 E(multiple)
93.6 214.8 Q F1(NORM_CMD\(ACK_REQ\))2.5 E F0 -.18(ro)2.5 G
(unds may be r).18 E(equir)-.18 E(ed to achieve r)-.18 E(esponses fr)
-.18 E(om all)-.18 E -.18(re)93.6 226.8 S(ceivers specified.).18 E
(The content of the attached)7.5 E F2(NormNodeId)2.5 E F0
(list will be dynamically)2.5 E(updated as this pr)93.6 238.8 Q
(ocess pr)-.18 E(ogr)-.18 E(esses and)-.18 E F1(NORM_ACK)2.5 E F0 -.18
(re)2.5 G(sponses ar).18 E 2.5(er)-.18 G(eceived fr)-2.68 E
(om the specified)-.18 E -.18(re)93.6 250.8 S(ceiver set.).18 E
(As the sender r)5 E(eceives valid r)-.18 E
(esponses \(i.e., matching watermark point or)-.18 E("ack_id"\) fr)93.6
262.8 Q(om r)-.18 E(eceivers, it SHALL eliminate those r)-.18 E
(eceivers fr)-.18 E(om the subsequent)-.18 E F1(NORM_CMD\(ACK_REQ\))93.6
274.8 Q F0(message "acking_node_list" and add in any pending r)2.5 E
(eceiver)-.18 E F2(NormNodeIds)93.6 286.8 Q F0(while keeping within the)
2.5 E F2(NormSegmentSize)2.5 E F0(limitation of the list size.)2.5 E
(Each)5 E -.18(re)93.6 298.8 S
(ceiver is queried a maximum number of times \().18 E F1
(NORM_ROBUST_FACTOR)A F0 2.5(,b)C 2.5(yd)-2.5 G(efault\).)-2.5 E
(Receivers not r)93.6 310.8 Q(esponding within this number of r)-.18 E
(epeated r)-.18 E(equests ar)-.18 E 2.5(er)-.18 G(emoved fr)-2.68 E
(om the)-.18 E(payload list to make r)93.6 322.8 Q
(oom for other potential r)-.18 E(eceivers pending acknowledgment.)-.18
E(The)5 E(transmission of the)93.6 334.8 Q F1(NORM_CMD\(ACK_REQ\))2.5 E
F0(is r)2.5 E(epeated until no further r)-.18 E(esponses ar)-.18 E(e)
-.18 E -.18(re)93.6 346.8 S(quir).18 E(ed or until the r)-.18 E
(epeat thr)-.18 E(eshold is exceeded for all pending r)-.18 E 2.5
(eceivers. The)-.18 F(transmission of)93.6 358.8 Q F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(or)2.5 E F1(NORM_CMD\(FLUSH\))2.5 E F0
(messages to conduct the)2.5 E(positive acknowledgment pr)93.6 370.8 Q
(ocess is multiplexed with ongoing sender data transmissions.)-.18 E
(However)93.6 382.8 Q 2.5(,t)-.74 G(he)-2.5 E F1(NORM_CMD\(FLUSH\))2.5 E
F0(positive acknowledgment pr)2.5 E(ocess may be interr)-.18 E(upted in)
-.08 E -.18(re)93.6 394.8 S(sponse to negative acknowledgment r).18 E
(epair r)-.18 E(equests \(NACKs\) r)-.18 E(eceived fr)-.18 E(om r)-.18 E
(eceivers)-.18 E(during the acknowledgment period.)93.6 406.8 Q(The)5 E
F1(NORM_CMD\(FLUSH\))2.5 E F0(positive acknowledgment)2.5 E(pr)93.6
418.8 Q(ocess is r)-.18 E(estarted for r)-.18 E
(eceivers pending acknowledgment once any the r)-.18 E(epairs have been)
-.18 E(transmitted.)93.6 430.8 Q(In the case of)93.6 454.8 Q F1
(NORM_CMD\(FLUSH\))2.5 E F0
(commands with an attached "acking_node_list", r)2.5 E(eceivers)-.18 E
(will not ACK until they have r)93.6 466.8 Q
(eceived complete transmission of all data up to and including)-.18 E
(the given watermark transmission point.)93.6 478.8 Q(All r)5 E
(eceivers SHALL interpr)-.18 E(et the watermark)-.18 E(point pr)93.6
490.8 Q(ovided in the r)-.18 E(equest NACK for r)-.18 E
(epairs if needed as for)-.18 E F1(NORM_CMD\(FLUSH\))2.5 E F0
(commands with no attached "acking_node_list".)93.6 502.8 Q/F3 10
/Palatino-Bold@0 SF 2.5(5.5.4. Group)72 526.8 R(Size Estimate)2.5 E F0
(NORM sender messages contain a "gsize" field that is a r)93.6 542.4 Q
(epr)-.18 E(esentation of the gr)-.18 E(oup size and)-.18 E
(is used in scaling random backof)93.6 554.4 Q 2.5(ft)-.18 G
(imer ranges.)-2.5 E(The use of the gr)5 E(oup size estimate within)-.18
E(the NORM pr)93.6 566.4 Q(otocol does not r)-.18 E(equir)-.18 E 2.5
(eap)-.18 G -.18(re)-2.5 G(cise estimation and works r).18 E
(easonably well if the)-.18 E(estimate is within an or)93.6 578.4 Q
(der of magnitude of the actual gr)-.18 E(oup size.)-.18 E
(By default, the NORM)5 E(sender gr)93.6 590.4 Q
(oup size estimate may be administratively configur)-.18 E 2.5
(ed. Also,)-.18 F(given the expected)2.5 E(scalability of the NORM pr)
93.6 602.4 Q(otocol for general use, a default value of 10,000 is)-.18 E
(RECOMMENDED for use as the gr)93.6 614.4 Q(oup size estimate.)-.18 E
(It is possible that gr)93.6 638.4 Q
(oup size may be algorithmically appr)-.18 E(oximated fr)-.18 E
(om the volume of)-.18 E(congestion contr)93.6 650.4 Q
(ol feedback messages which follow the exponentially weighted random)
-.18 E(backof)93.6 662.4 Q 2.5(f. However)-.18 F 2.5(,t)-.74 G
(he specification of such an algorithm is curr)-2.5 E
(ently beyond the scope of)-.18 E(this document.)93.6 674.4 Q
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Palatino-Bold@0 SF(6.)72
120 Q/F2 13/Palatino-Bold@0 SF(Security Considerations)5 E F0(The same \
security considerations that apply to the NORM, TFMCC, and FEC Building)
93.6 135.6 Q(Blocks also apply to the NORM pr)93.6 147.6 Q 2.5
(otocol. In)-.18 F(addition to vulnerabilities that any IP and IP)2.5 E
(multicast pr)93.6 159.6 Q(otocol implementation may be generally subje\
ct to, the NACK-based feedback of)-.18 E(NORM may be exploited by r)93.6
171.6 Q(eplay attacks which for)-.18 E
(ce the NORM sender to unnecessarily)-.18 E(transmit r)93.6 183.6 Q
(epair information.)-.18 E(This MA)5 E 2.5(Yb)-1.11 G 2.5(ea)-2.5 G(ddr)
-2.5 E(essed by network layer IP security)-.18 E
(implementations that guar)93.6 195.6 Q 2.5(da)-.18 G
(gainst this potential security exploitation.)-2.5 E(The NORM pr)5 E
(otocol)-.18 E
(is compatible with the use of the IP security \(IPsec\) ar)93.6 207.6 Q
(chitectur)-.18 E 2.5(ed)-.18 G(escribed in [6]. and the)-2.5 E
(IPSec Encapsulating Security Payload \(ESP\) pr)93.6 219.6 Q
(otocol or Authentication Header \(AF\))-.18 E(extension MA)93.6 231.6 Q
2.5(Yb)-1.11 G 2.5(eu)-2.5 G(sed to secur)-2.5 E 2.5(eI)-.18 G 2.5(Pp)
-2.5 G(ackets transmitted by NORM participants.)-2.5 E(Alternatively)
93.6 255.6 Q 2.5(,ah)-1.11 G
(eader extension may be applied to the NORM pr)-2.5 E(otocol to pr)-.18
E(ovide)-.18 E(authentication of NORM messages.)93.6 267.6 Q
(For this purpose the)5 E/F3 10/Courier@0 SF(EXT_AUTH)2.5 E F0
(header extension \(HET)2.5 E 2.5(=1)93.6 279.6 S 2.5(\)i)-2.5 G 2.5(sd)
-2.5 G 2.5(efined. The)-2.5 F
(format of this header extension and its pr)2.5 E
(ocessing is outside the scope of)-.18 E(this document and is to be com\
municated out-of-band as part of the session description.)93.6 291.6 Q
(It)5 E(is possible that an EXT_AUTH implementation of MA)93.6 303.6 Q
2.5(Ya)-1.11 G(lso pr)-2.5 E(ovide for encryption of)-.18 E
(NORM message payloads as well as authentication.)93.6 315.6 Q
(The use of this appr)5 E(oach as compar)-.18 E(ed)-.18 E
(to IPSec can allow for header compr)93.6 327.6 Q
(ession techniques to be applied jointly to IP and NORM)-.18 E(pr)93.6
339.6 Q(otocol headers.)-.18 E(In cases wher)5 E 2.5(es)-.18 G
(ecurity analysis deems that encryption of NORM pr)-2.5 E(otocol)-.18 E
(header content is beneficial or necessary)93.6 351.6 Q 2.5(,t)-1.11 G
(he afor)-2.5 E(ementioned use of IPSec ESP may be mor)-.18 E(e)-.18 E
(appr)93.6 363.6 Q 2.5(opriate. If)-.18 F(EXT_AUTH is pr)2.5 E
(esent, whatever packet authentication checks that can be)-.18 E
(performed immediately upon r)93.6 375.6 Q
(eception of the packet SHOULD be performed befor)-.18 E(e)-.18 E
(accepting the packet and performing any congestion contr)93.6 387.6 Q
(ol-r)-.18 E(elated action on it.)-.18 E(Some)5 E(packet authentication\
 schemes impose a delay of several seconds between when a packet is)93.6
399.6 Q -.18(re)93.6 411.6 S
(ceived and when the packet is fully authenticated.).18 E
(Any congestion contr)5 E(ol r)-.18 E(elated action)-.18 E(that is appr)
93.6 423.6 Q
(opriate MUST NOT be postponed by any such full packet authentication.)
-.18 E(Consideration SHOULD also be given to the potential for r)93.6
435.6 Q(eplay-attacks that would)-.18 E
(transplant authenticated packets fr)93.6 447.6 Q
(om one NORM session to another to disr)-.18 E(upt service.)-.08 E -.92
(To)5 G(avoid this potential, unique keys SHOULD be used on a per)93.6
459.6 Q(-session basis or NORM sender)-.18 E
(nodes SHOULD use unique "instance_id" identifiers that ar)93.6 471.6 Q
2.5(em)-.18 G(anaged as part of the security)-2.5 E
(association for the sessions.)93.6 483.6 Q(It is RECOMMENDED that such\
 security mechanisms be used when available.)93.6 507.6 Q(It should be)5
E(noted that NORM participants can use the "sequence" field fr)93.6
519.6 Q(om the NORM Common)-.18 E(Message Header to detect r)93.6 531.6
Q(eplay attacks.)-.18 E(This can be accomplished if the NORM sender is)5
E(willing to maintain state on r)93.6 543.6 Q(eceivers which ar)-.18 E
2.5(eN)-.18 G 2.5(ACKing. A)-2.5 F(cache of such r)2.5 E(eceiver state)
-.18 E(can be used to pr)93.6 555.6 Q(ovide pr)-.18 E
(otection against NACK r)-.18 E(eplay attacks.)-.18 E(NORM r)5 E
(eceivers SHOULD)-.18 E(also also maintain similar state for pr)93.6
567.6 Q(otection against possible r)-.18 E(eplay of other r)-.18 E
(eceiver)-.18 E(messages in ASM operation as well.)93.6 579.6 Q
(For example, a r)5 E(eceiver could be suppr)-.18 E(essed fr)-.18 E(om)
-.18 E(pr)93.6 591.6 Q(oviding NACK or congestion contr)-.18 E
(ol feedback by r)-.18 E(eplay of certain r)-.18 E(eceiver messages.)
-.18 E(For)5 E(these r)93.6 603.6 Q(easons, authentication of NORM mess\
ages \(e.g., via IPSec\) is RECOMMENDED for)-.18 E(pr)93.6 615.6 Q
(otection against similar attacks that might use fabricated messages.)
-.18 E(Also, encryption of)5 E(messages to pr)93.6 627.6 Q
(ovide confidientiality of application data and pr)-.18 E
(otect privacy of users MA)-.18 E(Y)-1.11 E
(also be applied using IPSec or similar mechanisms.)93.6 639.6 Q
(When any such cryptographic measur)5 E(es)-.18 E(ar)93.6 651.6 Q 2.5
(eu)-.18 G(sed, it is RECOMMENDED that an appr)-2.5 E
(oach such as described in the Gr)-.18 E(oup Domain of)-.18 E(Interpr)
93.6 663.6 Q(etation \(GDOI\) [28], Multimedia Internet KEY)-.18 E
(ing \(MIKEY\) [29] or Gr)-.55 E(oup Secur)-.18 E(e)-.18 E
(Association Key Management Pr)93.6 675.6 Q
(otocol \(GSAKMP\) [30] specifications for automated key)-.18 E
(management is applied.)93.6 687.6 Q
(It is also important to note that while NORM does leverage FEC-based r)
93.6 711.6 Q(epair for scalability)-.18 E(,)-1.11 E
(this does not alone guarantee integrity of r)93.6 723.6 Q
(eceived data.)-.18 E(Application-level integrity-)5 E(Adamson, et al.)
72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E([Page 62])116.525 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(checking of data content is highly RECOMMENDED.)93.6 120 Q/F1 10
/Palatino-Bold@0 SF(6.1.)72 156 Q/F2 12/Palatino-Bold@0 SF
(Baseline Secure NORM Operation)5 E F0
(This section describes a baseline mode of secur)93.6 171.6 Q 2.5(eN)
-.18 G(ORM pr)-2.5 E(otocol operation based on)-.18 E
(application of the IPSec security pr)93.6 183.6 Q 2.5(otocol. This)-.18
F(appr)2.5 E(oach is documented her)-.18 E 2.5(et)-.18 G 2.5(op)-2.5 G
-.18(ro)-2.5 G(vide a).18 E -.18(re)93.6 195.6 S(fer).18 E(ence, inter)
-.18 E(operable secur)-.18 E 2.5(em)-.18 G(ode of operation.)-2.5 E
(However)5 E 2.5(,a)-.74 G(dditional appr)-2.5 E(oaches to)-.18 E
(NORM security)93.6 207.6 Q 2.5(,i)-1.11 G
(ncluding other forms of IPSec application, MA)-2.5 E 2.5(Yb)-1.11 G 2.5
(es)-2.5 G(pecified in the futur)-2.5 E(e.)-.18 E(For example, the use \
of the EXT_AUTH header extension could enable NORM-specific)93.6 219.6 Q
(authentication or security encapsulation headers similar to those of I\
PSec to be specified and)93.6 231.6 Q(inserted into the NORM pr)93.6
243.6 Q(otocol message headers.)-.18 E(This would allow header compr)5 E
(ession)-.18 E(techniques to be applied to IP and NORM pr)93.6 255.6 Q
(otocol headers when needed in a similar)-.18 E(fashion to that of R)
93.6 267.6 Q(TP [22] and as pr)-.37 E
(eserved in the specification for Secur)-.18 E 2.5(eR)-.18 G(eal T)-2.5
E(ime)-.55 E(Pr)93.6 279.6 Q(otocol \(SR)-.18 E(TP\) [23].)-.37 E
(The baseline appr)5 E(oach described is applicable to NORM operation)
-.18 E(configur)93.6 291.6 Q(ed for SSM \(or SSM-like\) operation wher)
-.18 E 2.5(et)-.18 G(her)-2.5 E 2.5(ei)-.18 G 2.5(sas)-2.5 G
(ingle sender and the r)-2.5 E(eceivers)-.18 E(ar)93.6 303.6 Q 2.5(ep)
-.18 G -.18(ro)-2.5 G(viding unicast feedback.).18 E
(This form of NORM operation allows for IPSec to be used)5 E
(with a manageable number of security associations \(SA\).)93.6 315.6 Q
F1 2.5(6.1.1. IPSec)72 351.6 R(Approach)2.5 E F0
(For NORM one-to-many SSM operation with unicast feedback fr)93.6 367.2
Q(om r)-.18 E(eceivers, each node)-.18 E(SHALL be configur)93.6 379.2 Q
(ed with two transport mode IPSec security associations and)-.18 E(corr)
93.6 391.2 Q(esponding Security Policy Database \(SDP\) entries.)-.18 E
(One entry will be used for sender)5 E(-to-)-.18 E(gr)93.6 403.2 Q(oup \
multicast packet authentication and optionally encryption while the oth\
er entry will)-.18 E(be used to pr)93.6 415.2 Q
(ovide security for the unicast feedback messaging fr)-.18 E(om the r)
-.18 E(eceiver\(s\) to the)-.18 E(sender)93.6 427.2 Q(.)-.74 E
(The NORM sender SHALL use an IPSec SA configur)93.6 451.2 Q
(ed for ESP pr)-.18 E(otocol [7])-.18 E(operation with)5 E
(the option for data origination authentication enabled.)93.6 463.2 Q
(It is also RECOMMENDED that this)5 E(IPSec ESP SA be also configur)93.6
475.2 Q(ed to pr)-.18 E(ovide confidentiality pr)-.18 E
(otection for IP packets)-.18 E(containing NORM pr)93.6 487.2 Q
(otocol messages.)-.18 E(This is suggested to make the r)5 E
(ealization of complex)-.18 E -.18(re)93.6 499.2 S
(play attacks much mor).18 E 2.5(ed)-.18 G(if)-2.5 E 2.5(ficult. The)
-.18 F(encryption key for this SA SHALL be pr)2.5 E(eplaced at)-.18 E
(the sender and r)93.6 511.2 Q(eceiver\(s\) prior to NORM pr)-.18 E
(otocol operation.)-.18 E(Use of automated key)5 E
(management is RECOMMENDED as a r)93.6 523.2 Q(ekey SHALL be r)-.18 E
(equir)-.18 E(ed prior to expiration of the)-.18 E
(sequence space for the SA.)93.6 535.2 Q(This is necessary so that r)5 E
(eceivers may use the built-in IPSec)-.18 E -.18(re)93.6 547.2 S
(play attack pr).18 E
(otection possible for an IPSec SA with a single sour)-.18 E
(ce \(the NORM sender\).)-.18 E(Thus the r)93.6 559.2 Q
(eceivers SHALL enable r)-.18 E(eplay attack pr)-.18 E
(otection for this SA used to secur)-.18 E 2.5(eN)-.18 G(ORM)-2.5 E
(sender traf)93.6 571.2 Q 2.5(fic. An)-.18 F
(IPSec SPD entry MUST be configur)2.5 E(ed to pr)-.18 E
(ocess outbound packets to the)-.18 E(session \(destination\) addr)93.6
583.2 Q(ess and UDP port number of the applicable \()-.18 E/F3 10
/Palatino-Italic@0 SF(NormSession)A F0(\).)A(The NORM r)93.6 607.2 Q
(eceiver\(s\) MUST be configur)-.18 E
(ed with the SA and SPD entry to pr)-.18 E(operly pr)-.18 E(ocess)-.18 E
(the IPSec-secur)93.6 619.2 Q(ed packets fr)-.18 E(om the sender)-.18 E
5(.T)-.74 G(he NORM r)-5 E(eceiver\(s\) SHALL also use a)-.18 E(common,\
 second IPSec SA \(common Security Parameter Index \(SPI\) and encrypti\
on key\))93.6 631.2 Q(configur)93.6 643.2 Q(ed for ESP operation with t\
he option for data origination authentication enabled.)-.18 E
(Similar to the NORM sender)93.6 655.2 Q 2.5(,i)-.74 G 2.5(si)-2.5 G 2.5
(sR)-2.5 G(ECOMMENDED this IPSec ESP SA be also configur)-2.5 E(ed to)
-.18 E(pr)93.6 667.2 Q(ovide confidentiality pr)-.18 E
(otection for IP packets containing NORM pr)-.18 E(otocol messages.)-.18
E(The)5 E -.18(re)93.6 679.2 S
(ceivers MUST have an IPSec SPD entry configur).18 E(ed to pr)-.18 E
(ocess outbound NORM/UDP)-.18 E(packets dir)93.6 691.2 Q
(ected to the NORM sender sour)-.18 E(ce addr)-.18 E
(ess and port number using this second SA.)-.18 E
(As noted for NORM unicast feedback, the sender)93.6 703.2 Q
('s transmission port number SHOULD be).74 E(distinct fr)93.6 715.2 Q(o\
m the multicast session port number to allow discrimination between uni\
cast and)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(multicast feedback messages when access to the IP destination addr)93.6
120 Q(ess is not possible \(e.g., a)-.18 E(user)93.6 132 Q
(-space NORM implementation\).)-.18 E(For pr)5 E(ocessing of packets fr)
-.18 E(om r)-.18 E(eceivers, the NORM)-.18 E(sender SHALL be configur)
93.6 144 Q(ed with this common, second SA \(and the corr)-.18 E
(esponding SPD)-.18 E(entry needed\) in or)93.6 156 Q(der to pr)-.18 E
(operly pr)-.18 E(ocess messages fr)-.18 E(om the r)-.18 E(eceiver)-.18
E 5(.N)-.74 G(ote that built-in)-5 E(IPSec r)93.6 168 Q(eplay attack pr)
-.18 E(otection for this second SA at the sender MUST be disabled.)-.18
E(Multiple r)93.6 192 Q(eceivers using a common IPSec SA for traf)-.18 E
(fic dir)-.18 E(ected to the NORM sender \(i.e.,)-.18 E
(many-to-one\) pr)93.6 204 Q(events the use of built-in IPSec r)-.18 E
(eplay attack pr)-.18 E(otection by the NORM)-.18 E(sender with curr)
93.6 216 Q(ent IPSec implementations.)-.18 E
(So, to support a fully secur)5 E 2.5(em)-.18 G(ode of operation,)-2.5 E
(the NORM sender implementation MUST pr)93.6 228 Q(ovide r)-.18 E
(eplay attack pr)-.18 E(otection based upon the)-.18 E
("sequence" field of NORM pr)93.6 240 Q(otocol messages fr)-.18 E(om r)
-.18 E 2.5(eceivers. This)-.18 F(can be accomplished with)2.5 E
(high assurance of security)93.6 252 Q 2.5(,e)-1.11 G
(ven with the limited size \(16-bits\) of this field, because)-2.5 E
(1\))93.6 282 Q(NORM r)106.93 282 Q
(eceiver NACK and non-CLR ACK feedback messages ar)-.18 E 2.5(es)-.18 G
(parse.)-2.5 E(2\))93.6 306 Q(The mor)106.93 306 Q 2.5(ef)-.18 G -.18
(re)-2.5 G(quent NORM ACK feedback fr).18 E(om CLR or PLR nodes ar)-.18
E 2.5(eo)-.18 G(nly a small set of)-2.5 E -.18(re)106.93 318 S
(ceivers for which the sender must keep mor).18 E 2.5(ep)-.18 G
(ersistent r)-2.5 E(eplay attack state.)-.18 E(3\))93.6 342 Q
(NORM NACK feedback messages that pr)106.93 342 Q(ecede the sender)-.18
E('s curr).74 E(ent r)-.18 E(epair window do not)-.18 E
(significantly impact pr)106.93 354 Q
(otocol operation \(generation of NORM_CMD\(SQUELCH\) is limited\) and)
-.18 E(could be in fact ignor)106.93 366 Q 2.5(ed. This)-.18 F
(means the sender can pr)2.5 E(une any r)-.08 E
(eplay attack state for r)-.18 E(eceivers)-.18 E(that pr)106.93 378 Q
(ecede the curr)-.18 E(ent r)-.18 E(epair window)-.18 E(.)-.92 E(4\))
93.6 402 Q(NORM ACK messages corr)106.93 402 Q
(espond to either a specific sender "ack_id", the sender "cc_sequence")
-.18 E(for ACKs sent in r)106.93 414 Q
(esponse to NORM_CMD\(CC\), or the sender)-.18 E('s curr).74 E(ent r)
-.18 E(epair window in the)-.18 E(case of ACKs sent in r)106.93 426 Q
(esponse to NORM_CMD\(FLUSH\).)-.18 E(Thus, the sender can pr)5 E
(une any r)-.08 E(eplay)-.18 E(attack state for r)106.93 438 Q
(eceivers that pr)-.18 E(ecede the curr)-.18 E
(ent applicable sequence or r)-.18 E(epair window space.)-.18 E
(Note that use of ESP confidentiality)93.6 459.6 Q 2.5(,a)-1.11 G 2.5
(sR)-2.5 G(ECOMMENDED, for secur)-2.5 E 2.5(eN)-.18 G(ORM pr)-2.5 E
(otocol)-.18 E(operation makes it mor)93.6 471.6 Q 2.5(ed)-.18 G(if)-2.5
E(ficult for adversaries to conduct ef)-.18 E(fective r)-.18 E
(eplay attacks.)-.18 E(Additionally)93.6 483.6 Q 2.5(,i)-1.11 G 2.5(ts)
-2.5 G(hould be noted that a NORM sender implementation with access to \
the full)-2.5 E(ESP pr)93.6 495.6 Q(otocol header could also use the ES\
P sequence information to make this form of)-.18 E -.18(re)93.6 507.6 S
(play attack pr).18 E(otection even mor)-.18 E 2.5(er)-.18 G 2.5
(obust. The)-2.68 F(design of this baseline security appr)2.5 E
(oach for)-.18 E(NORM intentionally places any mor)93.6 519.6 Q 2.5(ec)
-.18 G(omplex pr)-2.5 E(ocessing state or pr)-.18 E(ocessing \(e.g. r)
-.18 E(eplay)-.18 E(attack pr)93.6 531.6 Q(otection given multiple r)
-.18 E(eceivers\) at the NORM sender since NORM r)-.18 E(eceiver)-.18 E
(implementations may need to have a mor)93.6 543.6 Q 2.5(e")-.18 G
(light-weight" r)-2.5 E(ealization in many cases.)-.18 E
(This baseline appr)93.6 567.6 Q(oach can be used for NORM pr)-.18 E
(otocol sessions with multiple senders if the)-.18 E
(SA pairs described ar)93.6 579.6 Q 2.5(ee)-.18 G
(stablished for each sender)-2.5 E 5(.F)-.74 G(or small-sized gr)-5 E
(oups, it is even)-.18 E(possible that many-to-many \(ASM\) IPSec confi\
guration could be achieved wher)93.6 591.6 Q 2.5(ee)-.18 G(ach)-2.5 E
(participant uses a unique SA \(with a unique SPI\).)93.6 603.6 Q
(This does not scale to lar)5 E(ger gr)-.18 E(oup sizes)-.18 E(given th\
e complex set of SA and SPD entries each participant would need to main\
tain.)93.6 615.6 Q
(It is anticipated in early deployments of this baseline appr)93.6 639.6
Q(oach to NORM security that key)-.18 E
(management will be conducted out-of-band with r)93.6 651.6 Q
(espect to NORM pr)-.18 E(otocol operation.)-.18 E(In)5 E
(the case of one-to-many NORM operation, it is possible that r)93.6
663.6 Q(eceivers may r)-.18 E(etrieve keying)-.18 E(information fr)93.6
675.6 Q(om a central server as needed or otherwise conduct gr)-.18 E
(oup key updates with a)-.18 E(similar centralized appr)93.6 687.6 Q 2.5
(oach. However)-.18 F 2.5(,i)-.74 G 2.5(tm)-2.5 G
(ay be possible with some key management)-2.5 E(schemes for r)93.6 699.6
Q(ekey messages to be transmitted to the gr)-.18 E
(oup as a message or transport object)-.18 E(within the NORM r)93.6
711.6 Q(eliable transfer session.)-.18 E(Similarly)5 E 2.5(,f)-1.11 G
(or gr)-2.5 E(oup-wise communication)-.18 E
(sessions it is possible that potential gr)93.6 723.6 Q
(oup participants may r)-.18 E(equest keying and/or r)-.18 E(ekeying)
-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18
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126.705(otocol Mar)-.18 F(ch 2007)-.18 E
(as part of NORM communications.)93.6 120 Q
(Additional specification is necessary to define an in-)5 E
(band key managment scheme for NORM sessions per)93.6 132 Q
(haps using the mechanisms of the)-.18 E(automated gr)93.6 144 Q
(oup key management specifications cited in this document.)-.18 E/F1 10
/Palatino-Bold@0 SF 2.5(6.1.2. IPSec)72 180 R(Requirements)2.5 E F0
(In or)93.6 195.6 Q(der to implement this secur)-.18 E 2.5(em)-.18 G
(ode of NORM pr)-2.5 E(otocol operation, the following IPSec)-.18 E
(capabilities ar)93.6 207.6 Q 2.5(er)-.18 G(equir)-2.68 E(ed.)-.18 E F1
2.5(6.1.2.1. Selectors)72 231.6 R F0
(The implementation MUST be able to use the sour)93.6 247.2 Q(ce addr)
-.18 E(ess, destination addr)-.18 E(ess, pr)-.18 E(otocol)-.18 E
(\(UDP\), and UDP port numbers as selectors in the SPD.)93.6 259.2 Q F1
2.5(6.1.2.2. Mode)72 283.2 R F0
(IPSec in transport mode MUST be supported.)93.6 298.8 Q
(The use of IPSec pr)5 E(ocessing for secur)-.18 E 2.5(eN)-.18 G(ORM)
-2.5 E(traf)93.6 310.8 Q(fic SHOULD also be "r)-.18 E(equir)-.18 E
(ed" such that unauthenticated packets ar)-.18 E 2.5(en)-.18 G(ot r)-2.5
E(eceived by the)-.18 E(NORM pr)93.6 322.8 Q(otocol implementation.)-.18
E([6].)5 E F1 2.5(6.1.2.3. Key)72 346.8 R(Management)2.5 E F0
(An automated key management scheme for gr)93.6 362.4 Q
(oup key distribution and r)-.18 E(ekeying such as)-.18 E
(GDOI [28], GSAKMP [30], or MIKEY [29] SHOULD be used.)93.6 374.4 Q
(Relatively short-lived NORM)5 E(sessions MA)93.6 386.4 Q 2.5(Yb)-1.11 G
2.5(ea)-2.5 G(ble to use Manual Keying with a single, pr)-2.5 E
(eplaced key)-.18 E 2.5(,p)-1.11 G(articularly if)-2.5 E(Extended Seque\
nce Numbering \(ESN\) [7] is available in the IPSec implementation used\
.)93.6 398.4 Q(It)5 E(should also be noted that it may be possible for \
key update messages \(e.g., the GDOI)93.6 410.4 Q(GROUPKEY)93.6 422.4 Q
(-PUSH message\) to be included in the NORM application r)-.92 E
(eliable data)-.18 E(transmission if appr)93.6 434.4 Q
(opriate interfaces wer)-.18 E 2.5(ea)-.18 G
(vailable between the NORM application and)-2.5 E
(the key management daemon.)93.6 446.4 Q F1 2.5(6.1.2.4. Security)72
470.4 R(Policy)2.5 E F0(Receivers SHOULD accept connections only fr)93.6
486 Q(om the designated, authorized sender\(s\).)-.18 E(It is)5 E
(expected that appr)93.6 498 Q(opriate key management will pr)-.18 E
(ovide encryption keys only to r)-.18 E(eceivers)-.18 E
(authorized to participate in a designated session.)93.6 510 Q(The appr)
5 E(oach outlined her)-.18 E 2.5(ea)-.18 G(llows)-2.5 E -.18(re)93.6 522
S(ceiver sets to be contr).18 E(olled on a per)-.18 E(-sender basis.)
-.18 E F1 2.5(6.1.2.5. Authentication)72 546 R(and Encryption)2.5 E F0
(Lar)93.6 561.6 Q(ge NORM gr)-.18 E
(oup sizes will necessitate some form of key management that does r)-.18
E(ely)-.18 E(upon shar)93.6 573.6 Q(ed secr)-.18 E 2.5(ets. The)-.18 F
(GDOI and GSAKMP pr)2.5 E(otocols mentioned her)-.18 E 2.5(ea)-.18 G
(llow for)-2.5 E(certificate-based authentication.)93.6 585.6 Q
(These certificates SHOULD use IP addr)5 E(esses for)-.18 E(authenticat\
ion although it may alternatively possible to have authentication assoc\
iated with)93.6 597.6 Q(pr)93.6 609.6 Q(e-assigned NormNodeId values.)
-.18 E(However)5 E 2.5(,i)-.74 G 2.5(ti)-2.5 G 2.5(sl)-2.5 G
(ikely that available gr)-2.5 E(oup key)-.18 E
(management implementations will not be NORM-specific.)93.6 621.6 Q F1
2.5(6.1.2.6. A)72 645.6 R(vailability)-.7 E F0(The IPSec r)93.6 661.2 Q
(equir)-.18 E(ements pr)-.18 E(ofile outlined her)-.18 E 2.5(ei)-.18 G
2.5(sc)-2.5 G(ommonly available on many potential)-2.5 E(NORM hosts.)
93.6 673.2 Q(The principal issue is that configuration and operation of\
 IPSec typically)5 E -.18(re)93.6 685.2 S(quir).18 E
(es privileged user authorization.)-.18 E
(Automated key management implementations ar)5 E(e)-.18 E
(typically configur)93.6 697.2 Q(ed with the privileges necessary to ef)
-.18 E(fect system IPSec configuration)-.18 E(needed.)93.6 709.2 Q
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Palatino-Bold@0 SF(7.)72
120 Q/F2 13/Palatino-Bold@0 SF(IANA Considerations)5 E F0
(Header extension identifiers for the NORM pr)93.6 135.6 Q(otocol ar)
-.18 E 2.5(es)-.18 G(ubject to IANA r)-2.5 E(egistration.)-.18 E
(Additionally)93.6 147.6 Q 2.5(,b)-1.11 G
(uilding blocks components used by this NORM Pr)-2.5 E
(otocol specification may)-.18 E(intr)93.6 159.6 Q
(oduce additional IANA considerations.)-.18 E(In particular)5 E 2.5(,t)
-.74 G(he FEC Building Block used by)-2.5 E(NORM does r)93.6 171.6 Q
(equir)-.18 E 2.5(eI)-.18 G(ANA r)-2.5 E
(egistration of the FEC codecs used.)-.18 E(The r)5 E(egistration instr)
-.18 E(uctions)-.08 E(for FEC codecs ar)93.6 183.6 Q 2.5(ep)-.18 G -.18
(ro)-2.5 G(vided in [4].).18 E F1(7.1.)72 207.6 Q F0
(This document defines a name-space for NORM Header Extensions named:)
93.6 235.2 Q/F3 10/Courier@0 SF(ietf:rmt:norm:extensions)226.8 247.2 Q
F0(These values r)93.6 271.2 Q(epr)-.18 E
(esent extended header fields that allow the pr)-.18 E
(otocol functionality to be)-.18 E
(expanded to include additional optional featur)93.6 283.2 Q
(es and operating modes.)-.18 E(The values that can)5 E
(be assigned within the ")93.6 295.2 Q F3(ietf:rmt:norm:extension)A F0
2.5("n)C(ame-space ar)-2.5 E 2.5(en)-.18 G(umeric indexes in)-2.5 E
(the range {0, 255}, boundaries included.)93.6 307.2 Q -.92(Va)5 G
(lues in the range {0,127} indicate variable length).92 E(extended head\
er fields while values in the range {128,255} indicate extension of a f\
ixed)93.6 319.2 Q(4-byte length.)93.6 331.2 Q
(NORM header extension indentifier value assignment r)5 E(equests ar)
-.18 E 2.5(eg)-.18 G(ranted)-2.5 E(on a "Specification Requir)93.6 343.2
Q(ed" basis as defined in [8].)-.18 E(Additional header extension)5 E
(specifications MUST include a description of pr)93.6 355.2 Q
(otocol actions to be taken when the the)-.18 E
(extended header is encounter)93.6 367.2 Q(ed by a pr)-.18 E
(otocol implementation not supporting that specific)-.18 E 2.5
(option. For)93.6 379.2 R(example, it may be possible for pr)2.5 E
(otocol implementations to ignor)-.18 E 2.5(eu)-.18 G(nknown)-2.5 E
(header extensions in many cases.)93.6 391.2 Q(This specification r)93.6
415.2 Q(egisters the following NORM Header Extension types in namespace)
-.18 E(")93.6 427.2 Q F3(ietf:rmt:norm:extensions)A F0(":)A .4 LW 511.53
449.7 72 449.7 DL -.92(Va)77 459.2 S 24.285(lue Name).92 F(Refer)167.185
E(ence)-.18 E 511.53 463.7 72 463.7 DL(1)94.53 473.2 Q F3(EXT_AUTH)17.5
E F0(This specification)17.5 E 511.53 477.7 72 477.7 DL(3)94.53 487.2 Q
F3(EXT_CC)23.5 E F0(This specification)23.5 E 511.53 491.7 72 491.7 DL
(64)89.53 501.2 Q F3(EXT_FTI)20.5 E F0(This specification)20.5 E 511.53
505.7 72 505.7 DL(128)84.53 515.2 Q F3(EXT_RATE)17.5 E F0
(This specification)17.5 E 511.53 519.7 72 519.7 DL 511.53 449.7 511.53
519.7 DL 72 449.7 72 519.7 DL 175.03 449.7 175.03 519.7 DL 109.53 449.7
109.53 519.7 DL F1(8.)72 557.2 Q F2(Suggested Use)5 E F0(The pr)93.6
572.8 Q(esent NORM pr)-.18 E(otocol is seen as useful tool for the r)
-.18 E(eliable data transfer over generic)-.18 E(IP multicast services.)
93.6 584.8 Q
(It is not the intention of the authors to suggest it is suitable for)5
E(supporting all envisioned multicast r)93.6 596.8 Q(eliability r)-.18 E
(equir)-.18 E 2.5(ements. NORM)-.18 F(pr)2.5 E(ovides a simple and)-.18
E(flexible framework for multicast applications with a degr)93.6 608.8 Q
(ee of concern for network traf)-.18 E(fic)-.18 E(implosion and pr)93.6
620.8 Q(otocol over)-.18 E(head ef)-.18 E(ficiency)-.18 E 5(.N)-1.11 G
(ORM-like pr)-5 E(otocols have been successfully)-.18 E(demonstrated wi\
thin the MBone for bulk data dissemination applications, including)93.6
632.8 Q(weather satellite compr)93.6 644.8 Q
(essed imagery updates servicing a lar)-.18 E(ge gr)-.18 E(oup of r)-.18
E(eceivers and a)-.18 E(generic web content r)93.6 656.8 Q
(eliable "push" application.)-.18 E(In addition, this framework appr)
93.6 680.8 Q(oach has some design featur)-.18 E
(es making it attractive for bulk)-.18 E(transfer in asymmetric and wir)
93.6 692.8 Q(eless internetwork applications.)-.18 E(NORM is capable of)
5 E(successfully operating independent of network str)93.6 704.8 Q
(uctur)-.08 E 2.5(ea)-.18 G(nd in envir)-2.5 E(onments with high)-.18 E
(packet loss, delay)93.6 716.8 Q 2.5(,a)-1.11 G(nd misor)-2.5 E 2.5
(dering. Hybrid)-.18 F(pr)2.5 E(oactive/r)-.18 E(eactive FEC-based r)
-.18 E(epairing)-.18 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E(impr)93.6 120 Q(ove pr)-.18 E
(otocol performance in some multicast scenarios.)-.18 E 2.5(As)5 G
(ender)-2.5 E(-only r)-.18 E(epair appr)-.18 E(oach)-.18 E
(often makes additional engineering sense in asymmetric networks.)93.6
132 Q(NORM's unicast)5 E(feedback capability may be suitable for use in\
 asymmetric networks or in networks wher)93.6 144 Q(e)-.18 E
(only unidir)93.6 156 Q(ectional multicast r)-.18 E
(outing/delivery service exists. Asymmetric ar)-.18 E(chitectur)-.18 E
(es)-.18 E(supporting multicast delivery ar)93.6 168 Q 2.5(el)-.18 G
(ikely to make up an important portion of the futur)-2.5 E(e)-.18 E
(Internet str)93.6 180 Q(uctur)-.08 E 2.5(e\()-.18 G
(e.g., DBS/cable/PSTN hybrids\) and ef)-2.5 E(ficient, r)-.18 E
(eliable bulk data transfer)-.18 E
(will be an important capability for servicing lar)93.6 192 Q(ge gr)-.18
E(oups of subscribed r)-.18 E(eceivers.)-.18 E/F1 10/Palatino-Bold@0 SF
(9.)72 216 Q/F2 13/Palatino-Bold@0 SF(Changes from RFC3940)5 E F0(This \
section lists the changes between the Experimental version of this spec\
ification, [10],)93.6 231.6 Q(and this version:)93.6 243.6 Q 25.17
(1\) Removal)97 259.2 R(of the)2.5 E/F3 10/Courier@0 SF
(NORM_FLAG_MSG_START)2.5 E F0(for)2.5 E F3(NORM_OBJECT_STREAM)2.5 E F0
2.5(,r)C(eplacing it)-2.68 E
(with the "payload_msg_start" field in the FEC-encoded pr)133 271.2 Q
(eamble of the)-.18 E F3(NORM_OBJECT_STREAM NORM_DATA)133 283.2 Q F0
(payload,)2.5 E 25.17(2\) Definition)97 298.8 R
(of IANA namespace for header extension assignment,)2.5 E 25.17
(3\) Removal)97 314.4 R
(of file blocking scheme description that is now specified in the FEC)
2.5 E(Building Block document [4],)133 326.4 Q 25.17(4\) Removal)97 342
R(of r)2.5 E(estriction of NORM r)-.18 E
(eceiver feedback message rate to local NORM)-.18 E
(sender rate \(this caused congestion contr)133 354 Q(ol failur)-.18 E
(es in high speed operation and the)-.18 E(extr)133 366 Q
(emely low feedback rate of the NORM pr)-.18 E(otocol as compar)-.18 E
(ed to TCP avoids any)-.18 E -.18(re)133 378 S
(sultant impact to the network [31]\),).18 E 25.17(5\) Corr)97 393.6 R
(ection of err)-.18 E(ors in some message format descriptions, and)-.18
E 25.17(6\) Corr)97 409.2 R
(ection of inconsistency in specification of the inactivity timeout.)
-.18 E 25.17(7\) Addition)97 424.8 R(of IPSec secur)2.5 E 2.5(em)-.18 G
(ode description with IPSec r)-2.5 E(equir)-.18 E(ements.)-.18 E 25.17
(8\) Clarification)97 440.4 R(of interpr)2.5 E(etation of "Sour)-.18 E
(ce Block Length" when FEC codes ar)-.18 E(e)-.18 E
(arbitrarily shortened by the sender)133 452.4 Q(.)-.74 E F1(10.)72
476.4 Q F2(Acknowledgments)5 E/F4 10/Palatino-Italic@0 SF
(\(and these ar)2.5 E 2.5(en)-.18 G(ot Negative\))-2.5 E F0
(The authors would like to thank Rick Jones, V)93.6 492 Q
(incent Roca, Rod W)-.55 E(alsh, T)-.92 E(oni Paila, Michael)-.92 E
(Luby)93.6 504 Q 2.5(,a)-1.11 G(nd Joer)-2.5 E 2.5(gW)-.18 G
(idmer for their valuable input and comments on this document.)-3.05 E
(The)5 E(authors would also like to thank the RMT working gr)93.6 516 Q
(oup chairs, Roger Kermode and)-.18 E(Lor)93.6 528 Q(enzo V)-.18 E(icis\
ano, for their support in development of this specification, and Sally \
Floyd for)-.55 E(her early input into this document.)93.6 540 Q F1 -.37
(11)72 564 S(.).37 E F2(References)5 E F1 -.37(11)72 588 S(.1.).37 E/F5
12/Palatino-Bold@0 SF(Normative References)5 E F0([1] Bradner)93.6 603.6
Q 2.5(,S)-.74 G 2.5(., "Key)-2.5 F(wor)2.5 E
(ds for use in RFCs to Indicate Requir)-.18 E
(ement Levels", BCP 14, RFC)-.18 E(21)93.6 615.6 Q(19, Mar)-.55 E
(ch 1997.)-.18 E
([2] Deering, S., "Host Extensions for IP Multicasting", STD 5, RFC 1)
93.6 639.6 Q -.55(11)-.55 G(2, August 1989.).55 E
([3] Adamson, B., Bormann, C., Handley)93.6 663.6 Q 2.5(,M)-1.11 G
(., and J. Macker)-2.5 E 2.5(,")-.74 G(Multicast Negative-)-2.5 E
(Acknowledgement \(NACK\) Building Blocks", draft-ietf-rmt-bb-norm-r)
93.6 675.6 Q(evised-03, July 2007.)-.18 E([4] W)93.6 699.6 Q
(atson, M., Luby)-.92 E 2.5(,M)-1.11 G(., and L. V)-2.5 E
(icisano, "Forwar)-.55 E 2.5(dE)-.18 G(rr)-2.5 E(or Corr)-.18 E
(ection \(FEC\) Building Block",)-.18 E(draft-ietf-rmt-fec-bb-r)93.6
711.6 Q(evised-07, April 2007.)-.18 E(Adamson, et al.)72 768 Q(Expir)
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/F0 10/Palatino-Roman@0 SF 116.025(Internet-Draft NORM)72 66 R(Pr)2.5 E
126.705(otocol Mar)-.18 F(ch 2007)-.18 E([5] J. W)93.6 120 Q
(idmer and M. Handley)-.55 E 2.5(,")-1.11 G
(TCP-Friendly Multicast Congestion Contr)-2.5 E(ol \(TFMCC\))-.18 E(Pr)
93.6 132 Q(otocol Specification", RFC 4654, August 2006.)-.18 E
([6] S. Kent and K. Seo, "Security Ar)93.6 156 Q(chitectur)-.18 E 2.5
(ef)-.18 G(or the Internet Pr)-2.5 E(otocol", RFC 4301, December)-.18 E
(2005.)93.6 168 Q([7] S. Kent, "IP Encapsulating Security Payload \(ESP\
\)", RFC 4303, December 2005.)93.6 192 Q([8] Narten, T)93.6 216 Q 2.5
(.a)-.74 G(nd H. Alvestrand, "Guidelines for W)-2.5 E
(riting an IANA Considerations Section in)-.74 E
(RFCs", BCP 26, RFC 2434, October 1998.)93.6 228 Q/F1 10/Palatino-Bold@0
SF -.37(11)72 264 S(.2.).37 E/F2 12/Palatino-Bold@0 SF
(Informative References)5 E F0([9] Kermode, R. and L. V)93.6 279.6 Q
(icisano, "Author Guidelines for Reliable Multicast T)-.55 E
(ransport \(RMT\))-.9 E(Building Blocks and Pr)93.6 291.6 Q
(otocol Instantiation documents", RFC 3269, April 2002.)-.18 E
([10] Adamson, B., Bormann, C., Handley)93.6 303.6 Q 2.5(,M)-1.11 G
(., and J. Macker)-2.5 E 2.5(,")-.74 G(Negative-Acknowledgement)-2.5 E
(\(NACK\)-Oriented Reliable Multicast \(NORM\) Pr)93.6 315.6 Q
(otocol", RFC 3940, November 2004.)-.18 E([1)93.6 339.6 Q(1] Handley)
-.55 E 2.5(,M)-1.11 G(., Jacobson, V)-2.5 E 2.5(.a)-1.29 G
(nd C. Perkins, "SDP: Session Description Pr)-2.5 E(otocol", RFC 4566,)
-.18 E(July 2006.)93.6 351.6 Q([12] Handley)93.6 375.6 Q 2.5(,M)-1.11 G
(., Perkins, C., and E. Whelan, "Session Announcement Pr)-2.5 E
(otocol", RFC 2974,)-.18 E(October 2000.)93.6 387.6 Q
([13] S. Pingali, D. T)93.6 411.6 Q(owsley)-.92 E 2.5(,J)-1.11 G 2.5(.K)
-2.5 G(ur)-2.5 E(ose, "A Comparison of Sender)-.18 E
(-Initiated and Receiver)-.18 E(-)-.18 E
(Initiated Reliable Multicast Pr)93.6 423.6 Q(otocols", In Pr)-.18 E
(oc. INFOCOM, San Francisco CA, October 1993.)-.18 E([14] Luby)93.6
447.6 Q 2.5(,M)-1.11 G(., V)-2.5 E
(icisano, L., Gemmell, J., Rizzo, L., Handley)-.55 E 2.5(,M)-1.11 G
(., and J. Cr)-2.5 E(owcr)-.18 E(oft, "The Use of)-.18 E(Forwar)93.6
459.6 Q 2.5(dE)-.18 G(rr)-2.5 E(or Corr)-.18 E
(ection \(FEC\) in Reliable Multicast", RFC 3453, December 2002.)-.18 E
([15] Macker)93.6 483.6 Q 2.5(,J)-.74 G 2.5(.a)-2.5 G
(nd B. Adamson, "The Multicast Dissemination Pr)-2.5 E(otocol \(MDP\) T)
-.18 E(oolkit",)-.92 E(Pr)93.6 495.6 Q
(oc. IEEE MILCOM 99, October 1999.)-.18 E([16] Nonnenmacher)93.6 519.6 Q
2.5(,J)-.74 G 2.5(.a)-2.5 G
(nd E. Biersack, "Optimal Multicast Feedback", Pr)-2.5 E(oc. IEEE)-.18 E
(INFOCOMM, p. 964, Mar)93.6 531.6 Q(ch/April 1998.)-.18 E
([17] J. Macker)93.6 555.6 Q 2.5(,B)-.74 G 2.5(.A)-2.5 G
(damson, "Quantitative Pr)-2.5 E
(ediction of Nack Oriented Reliable Multicast)-.18 E
(\(NORM\) Feedback", Pr)93.6 567.6 Q
(oc. IEEE MILCOM 2002, October 2002.)-.18 E([18] H.W)93.6 591.6 Q 2.5
(.H)-.92 G(olbr)-2.5 E
(ook, "A Channel Model for Multicast", Ph.D. Dissertation, Stanfor)-.18
E(d)-.18 E(University)93.6 603.6 Q 2.5(,D)-1.11 G
(epartment of Computer Science, Stanfor)-2.5 E
(d, California, August 2001.)-.18 E([19] D. Gossink, J. Macker)93.6
627.6 Q 2.5(,")-.74 G
(Reliable Multicast and Integrated Parity Retransmission with)-2.5 E
(Channel Estimation", IEEE GLOBECOMM 98', September 1998.)93.6 639.6 Q
([20] Whetten, B., V)93.6 663.6 Q(icisano, L., Kermode, R., Handley)-.55
E 2.5(,M)-1.11 G(., Floyd, S., and M. Luby)-2.5 E 2.5(,")-1.11 G
(Reliable)-2.5 E(Multicast T)93.6 675.6 Q
(ransport Building Blocks for One-to-Many Bulk-Data T)-.9 E
(ransfer", RFC 3048,)-.9 E(January 2001.)93.6 687.6 Q(Adamson, et al.)72
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126.705(otocol Mar)-.18 F(ch 2007)-.18 E([21] Mankin, A., Romanow)93.6
120 Q 2.5(,A)-.92 G(., Bradner)-2.5 E 2.5(,S)-.74 G(., and V)-2.5 E 2.5
(.P)-1.29 G(axson, "IETF Criteria for Evaluating)-2.5 E
(Reliable Multicast T)93.6 132 Q(ransport and Application Pr)-.9 E
(otocols", RFC 2357, June 1998.)-.18 E([22] Schulzrinne, H., Casner)93.6
156 Q 2.5(,S)-.74 G(., Fr)-2.5 E(ederick, R., and V)-.18 E 2.5(.J)-1.29
G(acobson, "R)-2.5 E(TP: A T)-.37 E(ransport Pr)-.9 E(otocol)-.18 E
(for Real-T)93.6 168 Q(ime Applications", STD 64, RFC 3550, July 2003.)
-.55 E([23] Baugher)93.6 192 Q 2.5(,M)-.74 G(., McGr)-2.5 E(ew)-.18 E
2.5(,D)-.92 G(., Naslund, M., Carrara, E., and K. Norrman, "The Secur)
-2.5 E 2.5(eR)-.18 G(eal)-2.5 E -.55(Ti)93.6 204 S(me T).55 E
(ransport Pr)-.9 E(otocol", RFC 371)-.18 E(1, Mar)-.55 E(ch 2004.)-.18 E
([24] J. W)93.6 228 Q(idmer and M. Handley)-.55 E 2.5(,")-1.11 G
(Extending Equation-Based Congestion Contr)-2.5 E(ol to Multicast)-.18 E
(Applications", Pr)93.6 240 Q
(oc ACM SIGCOMM 2001, San Diego, August 2001.)-.18 E([25] W)93.6 276 Q
(atson, M., "Basic Forwar)-.92 E 2.5(dE)-.18 G(rr)-2.5 E(or Corr)-.18 E
(ection \(FEC\) Schemes", Internet-Draft draft-ietf-)-.18 E
(rmt-bb-fec-basic-schemes-r)93.6 288 Q(evised-03, Febr)-.18 E
(uary 2007.)-.08 E([26] L. Rizzo, "pgmcc: A TCP-Friendly Single-Rate Mu\
lticast Congestion Contr)93.6 312 Q(ol Scheme",)-.18 E(Pr)93.6 324 Q
(oc ACM SIGCOMM 2000, Stockholm, August 2000.)-.18 E([27] J. Padhye, V)
93.6 348 Q 2.5(.F)-1.29 G(ir)-2.5 E(oiu, D. T)-.18 E(owsley)-.92 E 2.5
(,a)-1.11 G(nd J. Kur)-2.5 E(ose, "Modeling TCP Thr)-.18 E
(oughput: A Simple)-.18 E(Model and its Empirical V)93.6 360 Q
(alidation", Pr)-.92 E(oc ACM SIGCOMM 1998.)-.18 E([28] Baugher)93.6 384
Q 2.5(,M)-.74 G(., W)-2.5 E(eis, B., Har)-.92 E(djono, T)-.18 E
(., and H. Harney)-.74 E 2.5(,")-1.11 G(The Gr)-2.5 E(oup Domain of)-.18
E(Interpr)93.6 396 Q(etation", RFC 3547, July 2003.)-.18 E
([29] Arkko, J., Carrara, E., Lindholm, F)93.6 420 Q
(., Naslund, M., and K. Norrman, "MIKEY)-.92 E 2.5(:M)-.74 G(ultimedia)
-2.5 E(Internet KEY)93.6 432 Q(ing", RFC 3830, August 2004.)-.55 E
([30] Harney)93.6 456 Q 2.5(,H)-1.11 G(., Meth, U., Colegr)-2.5 E
(ove, A., and G. Gr)-.18 E(oss, "GSAKMP: Gr)-.18 E(oup Secur)-.18 E(e)
-.18 E(Association Key Management Pr)93.6 468 Q
(otocol", RFC 4535, June 2006.)-.18 E([31] Adamson, B. and J. Macker)
93.6 492 Q 2.5(,")-.74 G 2.5(AT)-2.5 G(CP-Friendly)-2.5 E 2.5(,R)-1.11 G
(ate-based Mechanism for NACK-)-2.5 E
(Oriented Reliable Multicast Congestion Contr)93.6 504 Q
(ol", IEEE GLOBECOMM 2001, November)-.18 E(2001.)93.6 516 Q
(Adamson, et al.)72 768 Q(Expir)87.875 E(es: 31 December 2007)-.18 E
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126.705(otocol Mar)-.18 F(ch 2007)-.18 E/F1 10/Palatino-Bold@0 SF(12.)72
120 Q/F2 13/Palatino-Bold@0 SF(Authors' Addresses)5 E F0(Brian Adamson)
93.6 135.6 Q(Naval Resear)93.6 147.6 Q(ch Laboratory)-.18 E -.92(Wa)93.6
159.6 S(shington, DC, USA, 20375).92 E(EMail: adamson@itd.nrl.navy)93.6
183.6 Q(.mil)-1.11 E(Carsten Bormann)93.6 219.6 Q(Universitaet Br)93.6
231.6 Q(emen TZI)-.18 E(Postfach 330440)93.6 243.6 Q(D-28334 Br)93.6
255.6 Q(emen, Germany)-.18 E(EMail: cabo@tzi.or)93.6 279.6 Q(g)-.18 E
(Mark Handley)93.6 315.6 Q(Department of Computer Science)93.6 327.6 Q
(University College London)93.6 339.6 Q(Gower Str)93.6 351.6 Q(eet)-.18
E(London)93.6 363.6 Q(WC1E 6BT)93.6 375.6 Q(UK)93.6 387.6 Q
(EMail: M.Handley@cs.ucl.ac.uk)93.6 411.6 Q(Joe Macker)93.6 447.6 Q
(Naval Resear)93.6 459.6 Q(ch Laboratory)-.18 E -.92(Wa)93.6 471.6 S
(shington, DC, USA, 20375).92 E(EMail: macker@itd.nrl.navy)93.6 495.6 Q
(.mil)-1.11 E(Adamson, et al.)72 768 Q(Expir)87.875 E
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