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(This document is a product of the IETF RMT WG and follo)54 192 Q
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288 Q(ets o)-.1 E -.15(ve)-.15 G 2.5(ran).15 G(etw)-2.5 E
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(Announcement Protocol \(SAP\) [6], etc\).)54 360 Q
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(3\))54 546 Q(non-\214nite streams of continuous data content \(NORM_OB\
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576 Q -1.21 -1.11(AT A)-.4 H(and NORM_OBJECT_FILE is simply to pro)3.61
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54 84 Q(produced content.)54 96 Q(The NORM_OBJECT_STREAM pro)5 E
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288 Q(Each sender maintains its NormT)5 E(ransportId assignments)-.35 E
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312 Q 2.5(ransportId. The)-.35 F(NormT)2.5 E(ransportIds are assigned)
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(group of this in an ef)54 348 Q(\214cient manner)-.25 E 5(.O)-.55 G(th\
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 that reliable multicast application v)54 360 Q
(ariants may construct dif)-.25 E(ferent, complete b)-.25 E(ulk)-.2 E
(transfer communication models to meet their goals.)54 372 Q(In summary)
54 396 Q 2.5(,t)-.65 G(he NORM protocol')-2.5 E 2.5(sg)-.55 G
(oal is to pro)-2.5 E(vide reliable transport of dif)-.15 E
(ferent types of data content \(including)-.25 E(potentially mix)54 408
Q(ed types\).)-.15 E(The senders enqueue and transmit b)5 E
(ulk content in the form of static data or \214les and/or non-\214nite,)
-.2 E(ongoing stream types.)54 420 Q(The sender will pro)5 E
(vide for repair transmission of this content in response to N)-.15 E
-.4(AC)-.35 G 2.5(Km).4 G(essages)-2.5 E(recei)54 432 Q -.15(ve)-.25 G
2.5(df).15 G(rom the recei)-2.5 E -.15(ve)-.25 G 2.5(rg).15 G 2.5
(roup. Mechanisms)-2.5 F(for "out-of-band" information and other transp\
ort control mechanisms are)2.5 E(speci\214ed for use by applications to\
 form complete reliable multicast solutions for dif)54 444 Q
(ferent purposes.)-.25 E/F2 10/Times-Bold@0 SF(1.2 NORM Scalability)36
468 Q F0
(Group communication scalability requirements lead to adaptation of ne)
54 492 Q -.05(ga)-.15 G(ti).05 E .3 -.15(ve a)-.25 H(ckno).15 E
(wledgement \(N)-.25 E -.4(AC)-.35 G(K\) based protocol).4 E
(schemes when feedback for reliability is required [7].)54 504 Q
(NORM is a protocol centered around the use of selecti)5 E .3 -.15(ve N)
-.25 H -.4(AC)-.2 G(Ks to).4 E(request repairs of missing data.)54 516 Q
(NORM pro)5 E(vides for the use of pack)-.15 E(et-le)-.1 E -.15(ve)-.25
G 2.5(lf).15 G(orw)-2.5 E(ard error correction \(FEC\) techniques for)
-.1 E(ef)54 528 Q(\214cient multicast repair and optional proacti)-.25 E
.3 -.15(ve t)-.25 H(ransmission rob).15 E 2.5(ustness[8]. FEC-based)-.2
F(repair can be used to greatly reduce)2.5 E(the quantity of reliable m\
ulticast repair requests and repair transmissions[9].)54 540 Q
(The principal f)5 E(actor in NORM scalability is the)-.1 E -.2(vo)54
552 S(lume of feedback traf).2 E(\214c generated by the recei)-.25 E
-.15(ve)-.25 G 2.5(rs).15 G(et to f)-2.5 E
(acilitate reliability and congestion control.)-.1 E(NORM uses)5 E
(probabilistic suppression of redundant feedback based on e)54 564 Q
(xponentially distrib)-.15 E(uted random back)-.2 E(of)-.1 E 2.5(ft)-.25
G 2.5(imers. The)-2.5 F(performance of this type of suppression relati)
54 576 Q .3 -.15(ve t)-.25 H 2.5(oo).15 G
(ther techniques is described in [10].)-2.5 E
(NORM dynamically measures the)5 E(group')54 588 Q 2.5(sr)-.55 G(oundtr\
ip timing status to set its suppression and other protocol timers.)-2.5
E(This allo)5 E(ws NORM to scale well while)-.25 E
(maintaining reliable data deli)54 600 Q -.15(ve)-.25 G
(ry transport with lo).15 E 2.5(wl)-.25 G(atenc)-2.5 E 2.5(yr)-.15 G
(elati)-2.5 E .3 -.15(ve t)-.25 H 2.5(ot).15 G(he netw)-2.5 E
(ork topology o)-.1 E -.15(ve)-.15 G 2.5(rw).15 G(hich it is operating.)
-2.5 E(Feedback messages can be either multicast to the group at lar)54
612 Q(ge or sent via unicast routing to the sender)-.18 E 5(.I)-.55 G
2.5(nt)-5 G(he case of)-2.5 E(unicast feedback, the sender "adv)54 624 Q
(ertises" the feedback state to the group to f)-.15 E
(acilitate feedback suppression.)-.1 E(In typical)5 E(Internet en)54 636
Q(vironments, it is e)-.4 E(xpected that the NORM protocol will readily\
 scale to group sizes on the order of tens of)-.15 E(thousands of recei)
54 648 Q -.15(ve)-.25 G 2.5(rs. A).15 F(study of the quantity of feedba\
ck for this type of protocol is described in [11].)2.5 E
(NORM is able to)5 E(Adamson, Borman, et al.)36 696 Q
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(operate with a smaller amount of feedback than a \
single TCP connection, e)54 84 Q -.15(ve)-.25 G 2.5(nw).15 G(ith relati)
-2.5 E -.15(ve)-.25 G(ly lar).15 E(ge numbers of recei)-.18 E -.15(ve)
-.25 G(rs.).15 E(Thus, depending upon the netw)54 96 Q(ork topology)-.1
E 2.5(,i)-.65 G 2.5(ti)-2.5 G 2.5(sp)-2.5 G
(ossible that NORM may scale to lar)-2.5 E(ger group sizes.)-.18 E -.4
(Wi)5 G(th respect to).4 E(computer resource usage, the NORM protocol d\
oes _not require that state be k)54 108 Q(ept on all recei)-.1 E -.15
(ve)-.25 G(rs in the group.).15 E(NORM)5 E
(senders maintain state only for recei)54 120 Q -.15(ve)-.25 G(rs pro)
.15 E(viding e)-.15 E(xplicit congestion control feedback.)-.15 E
(NORM recei)5 E -.15(ve)-.25 G(rs must maintain).15 E
(state for for each acti)54 132 Q .3 -.15(ve s)-.25 H(ender).15 E 5(.T)
-.55 G(his may constrain the number of simultaneous senders in some use\
s of NORM.)-5 E/F1 10/Times-Bold@0 SF(1.3 NORM En)36 156 Q(vir)-.4 E
(onmental Requir)-.18 E(ements and Considerations)-.18 E F0
(All of the en)54 180 Q(vironmental requirements and considerations tha\
t apply to the RMT FEC Building Block and the the RMT)-.4 E(TCP-Friendl\
y Multicast Congestion Control \(TFMCC\) Building Block also apply to N\
ORM.)54 192 Q(When the RMT GRA)5 E
(Building Block is used with NORM, its en)54 204 Q
(vironmental requirements and considerations SHALL also apply)-.4 E(.)
-.65 E
(The NORM protocol SHALL be capable of operating in an end-to-end f)54
228 Q(ashion with no assistance from intermediate systems)-.1 E(be)54
240 Q(yond basic IP multicast group management, routing, and forw)-.15 E
(arding services.)-.1 E(The NORM protocol SHOULD be)5 E
(compatible with techniques lik)54 252 Q 2.5(eG)-.1 G(eneric Router Ass\
ist \(GRA\) [12] for performance bene\214ts when applicable.)-2.5 E
(While the)5 E(techniques utilized in NORM are principally applicable t\
o "\215at" end-to-end IP multicast multicast topologies, the)54 264 Q
2.5(yc)-.15 G(ould)-2.5 E(also be applied in the sub-le)54 276 Q -.15
(ve)-.25 G(ls of hierarchical \(e.g. tree-based\) multicast distrib).15
E(ution if so desired.)-.2 E(NORM can mak)5 E 2.5(eu)-.1 G(se of)-2.5 E
(reciprocal \(among senders and recei)54 288 Q -.15(ve)-.25 G
(rs\) multicast communication under the An).15 E
(y-Source Multicast \(ASM\) model de\214ned in)-.15 E(RFC 1112 [13], b)
54 300 Q(ut SHALL also be capable of scalable operation in asymmetric t\
opologies such as Source Speci\214c)-.2 E(Multicast \(SSM\) [14] where \
there may only be unicast routing service from the recei)54 312 Q -.15
(ve)-.25 G(rs to the sender\(s\).).15 E
(NORM is compatible with IPv4 and IPv6.)54 336 Q(Additionally)5 E 2.5
(,N)-.65 G(ORM may be used with netw)-2.5 E(orks emplo)-.1 E(ying Netw)
-.1 E(ork Address)-.1 E -.35(Tr)54 348 S(anslation \(N).35 E -1.11(AT)
-.35 G 2.5(\)p)1.11 G(ro)-2.5 E(viding the N)-.15 E 2.22 -1.11(AT d)-.35
H -.25(ev)1.11 G(ice supports IP multicast and/or can cache UDP traf).25
E(\214c source port numbers for)-.25 E(remapping feedback traf)54 360 Q
(\214c from recei)-.25 E -.15(ve)-.25 G(rs to the sender\(s\).).15 E F1
(2.0 NORM Ar)36 384 Q(chitectur)-.18 E 2.5(eD)-.18 G(e\214nition)-2.5 E
F0(A)54 408 Q/F2 10/Times-Italic@0 SF(NormSession)2.5 E F0
(is comprised of participants \()2.5 E F2(NormNodes)A F0 2.5(\)a)C
(cting as senders and/or recei)-2.5 E -.15(ve)-.25 G 2.5(rs. NORM).15 F
(senders transmit data)2.5 E(content in the form of)54 420 Q F2
(NormObjects)2.5 E F0
(to the session destination address and the NORM recei)2.5 E -.15(ve)
-.25 G(rs attempt to reliably recei).15 E -.15(ve)-.25 G
(the transmitted content using ne)54 432 Q -.05(ga)-.15 G(ti).05 E .3
-.15(ve a)-.25 H(ckno).15 E(wledgments to request repair)-.25 E 5(.E)
-.55 G(ach NormNode within a NormSession is)-5 E(assumed to ha)54 444 Q
.3 -.15(ve a p)-.2 H(reselected unique 32-bit identi\214er \().15 E F2
(NormNodeId)A F0 2.5(\). NormNodes)B(MUST ha)2.5 E .3 -.15(ve u)-.2 H
(niquely assigned).15 E
(identi\214ers within a single NormSession to distinquish)54 456 Q
(between possible multiple senders and to distinguish feedback)5 E
(information from dif)54 468 Q(ferent recei)-.25 E -.15(ve)-.25 G 2.5
(rs. There).15 F(are tw)2.5 E 2.5(or)-.1 G(eserv)-2.5 E(ed NormNodeId v)
-.15 E 2.5(alues. A)-.25 F -.25(va)2.5 G(lue of).25 E/F3 10/Courier@0 SF
(0x00000000)2.5 E F0(is considered)2.5 E(an in)54 480 Q -.25(va)-.4 G
(lid NormNodeId v).25 E(alue and a v)-.25 E(alue of)-.25 E F3
(0xffffffff)2.5 E F0(is a "wildcard" NormNodeId.)2.5 E
(Whilte, the protocol does not)5 E(preclude multiple sender nodes concu\
rrently transmitting within the conte)54 492 Q
(xt of a single NORM session \(i.e. man)-.15 E(y- to-man)-.15 E(y)-.15 E
(operation\), an)54 504 Q 2.5(yt)-.15 G(ype of interacti)-2.5 E .3 -.15
(ve c)-.25 H(oordination among NORM senders is assumed to be controlled\
 by the application or).15 E(higher protocol layer)54 516 Q 5(.T)-.55 G
(here are some optional mechanisms speci\214ed in this document which c\
an be le)-5 E -.15(ve)-.25 G(raged for such).15 E
(application layer coordination.)54 528 Q(As pre)54 552 Q
(viusly noted, NORM allo)-.25 E
(ws for reliable transmission of three dif)-.25 E
(ferent basic types of data content.)-.25 E(The \214rst type is)5 E F3
(NORM_OBJECT_DATA)54 564 Q F0(which is used for static, persistent bloc\
ks of data content maintained in the sender')2.5 E 2.5(sa)-.55 G
(pplication)-2.5 E(memory storage.)54 576 Q(The second type is)5 E F3
(NORM_OBJECT_FILE)2.5 E F0
(which corresponds to data stored in the sender')2.5 E 2.5(sn)-.55 G
(on-v)-2.5 E(olatile)-.2 E(\214le system.)54 588 Q(The)5 E F3
(NORM_OBJECT_DATA)2.5 E F0(and)2.5 E F3(NORM_OBJECT_FILE)2.5 E F0
(types both represent "NormObjects" of \214nite b)2.5 E(ut)-.2 E
(potentially v)54 600 Q(ery lar)-.15 E(ge size.)-.18 E
(The third type of data content is)5 E F3(NORM_OBJECT_STREAM)2.5 E F0
(which corresponds to an ongoing)2.5 E
(transmission of unde\214ned length.)54 612 Q
(This is analogous to the reliable streaming content pro)5 E
(vide by TCP for unicast data)-.15 E 2.5(transport. The)54 624 R(format\
 of the stream content is application-de\214ned and may be byte or mess\
age oriented.)2.5 E(The NORM)5 E(protocol pro)54 636 Q
(vides for "\215ushing" of the stream to e)-.15 E(xpedite deli)-.15 E
-.15(ve)-.25 G(ry or possible enforce application message boundaries.)
.15 E(NORM protocol implementations may of)54 648 Q
(fer either \(or both\) in-order deli)-.25 E -.15(ve)-.25 G
(ry of the stream data to the recei).15 E .3 -.15(ve a)-.25 H
(pplication or).15 E(Adamson, Borman, et al.)36 696 Q
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(out-of-order \(more immediate\) deli)54 84 Q -.15
(ve)-.25 G(ry of recei).15 E -.15(ve)-.25 G 2.5(ds).15 G -.15(eg)-2.5 G
(ments of the stream to the recei).15 E -.15(ve)-.25 G 2.5(ra).15 G 2.5
(pplication. In)-2.5 F(either case,)2.5 E(NORM sender and recei)54 96 Q
-.15(ve)-.25 G 2.5(ri).15 G(mplementations pro)-2.5 E(vide b)-.15 E(uf)
-.2 E(fering to f)-.25 E
(acilitate repair of the stream as it is transported.)-.1 E(All)5 E
(NormObjects are logically se)54 108 Q
(gmented into FEC coding blocks and se)-.15 E
(gments for transmission by the sender)-.15 E(.)-.55 E
(NormObjects and associated transmission se)54 132 Q(gments are tempora\
rily yet uniquely identi\214ed within the NormSession conte)-.15 E(xt)
-.15 E(using the gi)54 144 Q -.15(ve)-.25 G 2.5(ns).15 G(ender')-2.5 E
2.5(sN)-.55 G(ormNodeId and a temporarily unique NormObjectT)-2.5 E 2.5
(ransportId. These)-.35 F(data content identi\214ers are)2.5 E(sender)54
156 Q(-assigned and applicable and v)-.2 E
(alid only during a NormObject')-.25 E 2.5(sa)-.55 G
(ctual _transport_ \(i.e. for as long as the sender is)-2.5 E
(transmitting and pro)54 168 Q
(viding repair of the indicated NormObject\).)-.15 E -.15(Fo)5 G 2.5
(ral).15 G(ong-li)-2.5 E -.15(ve)-.25 G 2.5(ds).15 G
(ession, the NormObjectT)-2.5 E(ransportId \214eld)-.35 E
(can wrap and pre)54 180 Q(viously-used identi\214ers may be re-used.)
-.25 E
(Note that globally unique identi\214cation of transported data content)
5 E(is not pro)54 192 Q(vided by NORM and, if required, must be managed\
 by the NORM application.)-.15 E(Indi)5 E(vidual NormObject se)-.25 E
(gments)-.15 E
(are further identi\214ed with FEC coding block and symbol \(se)54 204 Q
(gment\) indenti\214ers.)-.15 E
(This is discussed in detail later in this)5 E(document.)54 216 Q/F1 10
/Times-Bold@0 SF(2.1 NORM Pr)36 240 Q(otocol Operation Ov)-.18 E(er)-.1
E(view)-.1 E F0 2.5(AN)54 264 S
(ORM sender primarily generates messages of type)-2.5 E/F2 10/Courier@0
SF(NORM_DATA)2.5 E F0(that carry the NormObject data content se)2.5 E
(gments and)-.15 E(related FEC parity-based repair se)54 276 Q
(gments for the b)-.15 E
(ulk data/\214le or stream objects being transferred.)-.2 E(By def)5 E
(ault, FEC)-.1 E(se)54 288 Q(gments are sent only in response to recei)
-.15 E -.15(ve)-.25 G 2.5(rr).15 G(epair requests \(N)-2.5 E -.4(AC)-.35
G(Ks\) and thus normally impose no additional transmission).4 E -.15
(ove)54 300 S 2.5(rhead. Ho).15 F(we)-.25 E -.15(ve)-.25 G .8 -.4(r, t)
.15 H(he NORM implementation MA).4 E 2.5(Yb)-1.05 G 2.5(eo)-2.5 G
(ptionally con\214gured to proacti)-2.5 E -.15(ve)-.25 G
(ly transmit some amount of FEC).15 E(se)54 312 Q(gments along with the\
 data content to potentially enhance performance \(e.g., impro)-.15 E
-.15(ve)-.15 G 2.5(dd).15 G(elay\) at the cost of additional)-2.5 E -.15
(ove)54 324 S(rhead with initial data transmission.).15 E
(This con\214guration may be sensible for certain netw)5 E
(ork conditions and can allo)-.1 E 2.5(wf)-.25 G(or)-2.5 E(rob)54 336 Q
(ust, asymmetric multicast \(e.g., unidirectional routing, satellite, c\
able\) [19] with reduced recei)-.2 E -.15(ve)-.25 G 2.5(rf).15 G
(eedback, or)-2.5 E 2.5(,i)-.4 G 2.5(ns)-2.5 G(ome)-2.5 E
(cases, no feedback.)54 348 Q 2.5(As)54 372 S(ender message of type)-2.5
E F2(NORM_INFO)2.5 E F0(is also de\214ned and is used to carry an)2.5 E
2.5(yo)-.15 G(ptional "out-of-band" conte)-2.5 E(xt information)-.15 E
(for a gi)54 384 Q -.15(ve)-.25 G 2.5(nt).15 G(ransport object.)-2.5 E
2.5(As)5 G(ingle)-2.5 E F2(NORM_INFO)2.5 E F0
(message can be associated with a NormObject.)2.5 E
(Because of its atomic)5 E(nature, missing)54 396 Q F2(NORM_INFO)2.5 E
F0(messages can be N)2.5 E -.4(AC)-.35 G -.25(Ke).4 G 2.5(da).25 G
(nd repaired with a slightly lo)-2.5 E(wer delay process than NORM')-.25
E(s)-.55 E(general FEC-encoded data content.)54 408 Q F2(NORM_INFO)2.5 E
F0(may serv)2.5 E 2.5(es)-.15 G(pecial purposes for some b)-2.5 E
(ulk transfer)-.2 E 2.5(,r)-.4 G(eliable multicast)-2.5 E
(applications where recei)54 420 Q -.15(ve)-.25 G
(rs join the group mid-stream and need to ascertain conte).15 E
(xtual information on the current content)-.15 E(being transmitted.)54
432 Q(The N)5 E -.4(AC)-.35 G 2.5(Kp).4 G(rocess for)-2.5 E F2
(NORM_INFO)2.5 E F0(will be described later)2.5 E(.)-.55 E
(The sender also generates messages of type)54 456 Q F2(NORM_CMD)2.5 E
F0(to assist in certain protocol operations such as congestion control,)
2.5 E(end-of-transmission \215ushing, round trip time estimation, recei)
54 468 Q -.15(ve)-.25 G 2.5(rs).15 G
(ynchronization, and optional positi)-2.5 E .3 -.15(ve a)-.25 H(ckno).15
E(wledgement)-.25 E(requests or application de\214ned commands.)54 480 Q
(The transmission of)5 E F2(NORM_CMD)2.5 E F0
(messages from the sender is accomplished by)2.5 E(one of three dif)54
492 Q(ferent processes.)-.25 E(These are: single, best ef)5 E
(fort unreliable transmission of the command; repeated redundant)-.25 E
(transmissions of the command; and positi)54 504 Q -.15(ve)-.25 G
(ly-ackno).15 E(wledged commands.)-.25 E
(The transmission technique used for a gi)5 E -.15(ve)-.25 G(n).15 E
(command depends upon the function of the command.)54 516 Q(Se)5 E -.15
(ve)-.25 G
(ral core commands are de\214ned for basic protocol operation.).15 E
(Additionally)54 528 Q 2.5(,i)-.65 G(mplementations MA)-2.5 E 2.5(Yw)
-1.05 G(ish to consider pro)-2.5 E(viding the OPTION)-.15 E
(AL application-de\214ned commands that can)-.35 E(tak)54 540 Q 2.5(ea)
-.1 G(dv)-2.5 E(antage of the transmission methodologies a)-.25 E -.25
(va)-.2 G(ilable for commands.).25 E(This allo)5 E
(ws for application-le)-.25 E -.15(ve)-.25 G 2.5(ls).15 G(ession)-2.5 E
(management mechanisms which can mak)54 552 Q 2.5(eu)-.1 G
(se of information a)-2.5 E -.25(va)-.2 G
(ilable to the underlying NORM protocol engine \(e.g.).25 E
(round-trip timing, transmission rate, etc\).)54 564 Q(NORM recei)54 588
Q -.15(ve)-.25 G(rs generate messages of type).15 E F2(NORM_NACK)2.5 E
F0(or)2.5 E F2(NORM_ACK)2.5 E F0
(in response to transmissions of data and)2.5 E(commands from a sender)
54 600 Q 5(.T)-.55 G(he)-5 E F2(NORM_NACK)2.5 E F0(messages are generat\
ed to request repair of detected data transmission losses.)2.5 E(Recei)
54 612 Q -.15(ve)-.25 G(rs generally detect losses by tracking the sequ\
ence of transmission from a sender).15 E 5(.S)-.55 G
(equencing information is)-5 E(embedded in the transmitted data pack)54
624 Q(ets and end-of-transmission commands from the sender)-.1 E(.)-.55
E F2(NORM_ACK)5 E F0(messages are)2.5 E
(generated in response to certain commands transmitted by the sender)54
636 Q 5(.I)-.55 G 2.5(nt)-5 G
(he general \(and most scalable\) protocol mode,)-2.5 E F2(NORM_ACK)54
648 Q F0(messages are sent only in response to congestion control comma\
nds from the sender)2.5 E 5(.T)-.55 G(he feedback v)-5 E(olume of)-.2 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)123.25 E(age 5])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(these congestion control)54 84 Q/F1 10/Courier@0
SF(NORM_ACK)2.5 E F0(messages is controlled using the same timer)2.5 E
(-based probabilistic suppression techniques)-.2 E(as for)54 96 Q F1
(NORM_NACK)2.5 E F0(messages to a)2.5 E -.2(vo)-.2 G
(id feedback implosion.).2 E
(In order to meet potential application requirements for positi)5 E -.15
(ve)-.25 G(ackno)54 108 Q(wledgement from recei)-.25 E -.15(ve)-.25 G
(rs, other).15 E F1(NORM_ACK)2.5 E F0(messages are de\214ned and a)2.5 E
-.25(va)-.2 G(ilable for use.).25 E(All sender and recei)5 E -.15(ve)
-.25 G(r).15 E(transmissions are subject to rate control go)54 120 Q
-.15(ve)-.15 G(rned by a peak transmission rate set for each participan\
t by the application.).15 E(This can be used to limit the quantity of m\
ulticast data transmitted by the group.)54 132 Q(When NORM')5 E 2.5(sc)
-.55 G(ongestion control)-2.5 E
(algorithm is enabled the rate for senders is automatically adjusted.)54
144 Q(In some netw)5 E(orks, it may be desirable to establish)-.1 E(min\
imum and maximum bounds for the rate adjustment depending upon the appl\
ication e)54 156 Q -.15(ve)-.25 G 2.5(nw).15 G(hen dynamic congestion)
-2.5 E(control is enabled.)54 168 Q(Ho)5 E(we)-.25 E -.15(ve)-.25 G .8
-.4(r, i).15 H 2.5(nt).4 G
(he case of the general Internet, congestion control polic)-2.5 E 2.5
(yS)-.15 G(HALL be observ)-2.5 E(ed which is)-.15 E(compatible with coe)
54 180 Q(xistent TCP \215o)-.15 E(ws.)-.25 E/F2 10/Times-Bold@0 SF
(2.2 NORM Pr)36 204 Q(otocol Building Blocks)-.18 E F0(The operation of\
 the NORM protocol is based upon the concepts presented in the Nack-Ori\
ented Reliable Multicast)54 228 Q(\(NORM\) Building Block document[15].)
54 240 Q(This includes the basic NORM architecture and the data transmi\
ssion, repair)5 E 2.5(,a)-.4 G(nd)-2.5 E(feedback strate)54 252 Q
(gies discussed in that document.)-.15 E(NORM also mak)5 E(es use of F)
-.1 E(orw)-.15 E(ard Error Correction encoding techiques for)-.1 E
(repair messaging and optional transmission rob)54 264 Q
(ustness as described in [16].)-.2 E(NORM uses the FEC P)5 E
(ayload ID as speci\214ed)-.15 E
(by the FEC Building Block Document[17].)54 276 Q(Additionally)5 E 2.5
(,f)-.65 G
(or congestion control, the NORM protocol speci\214es a mechanism)-2.5 E
(based on the TCP-Friendly Multicast Congestion Control \(TFMCC\) Build\
ing Block described in [18].)54 288 Q F2(2.3 NORM Design T)36 312 Q
(radeoffs)-.74 E F0(While the v)54 336 Q
(arious features of NORM are designed to pro)-.25 E
(vide some measure of general purpose utility)-.15 E 2.5(,i)-.65 G 2.5
(ti)-2.5 G 2.5(si)-2.5 G(mportant to)-2.5 E(emphasize the understanding\
 that "no one size \214ts all" in the reliable multicast transport aren\
a.)54 348 Q(There are numerous)5 E(engineering tradeof)54 360 Q(fs in)
-.25 E -.2(vo)-.4 G(lv).2 E(ed in reliable multicast transport design a\
nd this requires an increased a)-.15 E -.1(wa)-.15 G
(reness of application).1 E(and netw)54 372 Q
(ork architecture considerations.)-.1 E(Performance requirements af)5 E
(fecting design can include:)-.25 E(group size, heterogeneity)5 E
(\(e.g., capacity and/or delay\), asymmetric deli)54 384 Q -.15(ve)-.25
G(ry).15 E 2.5(,d)-.65 G(ata ordering, deli)-2.5 E -.15(ve)-.25 G
(ry delay).15 E 2.5(,g)-.65 G(roup dynamics, mobility)-2.5 E 2.5(,c)-.65
G(ongestion)-2.5 E(control, and transport across lo)54 396 Q 2.5(wc)-.25
G(apacity connections.)-2.5 E(NORM contains v)5 E
(arious parameters to accommodate man)-.25 E 2.5(yo)-.15 G 2.5(ft)-2.5 G
(hese)-2.5 E(dif)54 408 Q(fering requirements.)-.25 E
(The NORM protocol and its mechanisms MA)5 E 2.5(Yb)-1.05 G 2.5(ea)-2.5
G(pplied in multicast applications outside of b)-2.5 E(ulk)-.2 E
(data transfer)54 420 Q 2.5(,b)-.4 G(ut there is an assumed model of b)
-2.7 E(ulk transfer transport service that dri)-.2 E -.15(ve)-.25 G 2.5
(st).15 G(he trade-of)-2.5 E(fs that determine the)-.25 E
(scalability and performance described in this document.)54 432 Q
(The ability of NORM to pro)54 456 Q(vide reliable data deli)-.15 E -.15
(ve)-.25 G(ry is also go).15 E -.15(ve)-.15 G(rned by an).15 E 2.5(yb)
-.15 G(uf)-2.7 E(fer constraints of the sender and recei)-.25 E -.15(ve)
-.25 G(r).15 E 2.5(applications. NORM)54 468 R(protocol implementations\
 SHOULD be designed to operate with the greatest ef)2.5 E(\214cienc)-.25
E 2.5(ya)-.15 G(nd rob)-2.5 E(ustness)-.2 E
(possible within application-de\214ned b)54 480 Q(uf)-.2 E
(fer constraints.)-.25 E(Buf)5 E(fer requirements for reliability)-.25 E
2.5(,a)-.65 G 2.5(sa)-2.5 G -.1(lwa)-2.5 G(ys, are a function of the).1
E(delay-bandwidth product of the netw)54 492 Q(ork topology)-.1 E 5(.N)
-.65 G(ORM performs best with additional b)-5 E(uf)-.2 E
(fering as compared to typical)-.25 E(point-to-point transport NORM fee\
dback suppression based upon randomly-delayed transmissions from the re\
cei)54 504 Q -.15(ve)-.25 G 2.5(rs).15 G(et.)-2.5 E
(There are de\214niti)54 516 Q .3 -.15(ve t)-.25 H(radeof).15 E
(fs between b)-.25 E(uf)-.2 E(fer utilization, group size scalability)
-.25 E 2.5(,a)-.65 G(nd ef)-2.5 E(\214cienc)-.25 E 2.5(yo)-.15 G 2.5(fp)
-2.5 G 2.5(erformance. Lar)-2.5 F(ge b)-.18 E(uf)-.2 E(fer)-.25 E
(sizes allo)54 528 Q 2.5(wt)-.25 G(he NORM protocol to perform most ef)
-2.5 E(\214ciently in lar)-.25 E(ge delay-bandwidth topologies and allo)
-.18 E 2.5(wf)-.25 G(or longer)-2.5 E(feedback suppression back)54 540 Q
(of)-.1 E 2.5(ft)-.25 G 2.5(imeouts. This)-2.5 F(yields impro)2.5 E -.15
(ve)-.15 G 2.5(dg).15 G(roup size scalability)-2.5 E 5(.N)-.65 G
(ORM can operate with reduced)-5 E -.2(bu)54 552 S -.25(ff).2 G(ering b)
.25 E(ut at a cost of decreased ef)-.2 E(\214cienc)-.25 E 2.5(y\()-.15 G
(lo)-2.5 E(wer relati)-.25 E .3 -.15(ve g)-.25 H
(oodput\) and reduced group size scalability).15 E(.)-.65 E F2(3.0 Conf)
36 576 Q(ormance Statement)-.25 E F0
(This Protocol Instantiation document, in conjunction with the follo)54
600 Q(wing Building Block documents identi\214ed in [15], [16],)-.25 E
([17], and [18] completely speci\214es a w)54 612 Q(orking reliable mul\
ticast transport protocol that conforms to the requirements)-.1 E
(described in RFC 2357 [3].)54 624 Q F2(4.0 NORM Message F)36 648 Q
(ormats)-.25 E F0(Adamson, Borman, et al.)36 696 Q
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(As mentioned in Section 2.1, there are tw)54 84 Q
2.5(op)-.1 G(rimary classes of NORM messages: sender messages and recei)
-2.5 E -.15(ve)-.25 G 2.5(rm).15 G(essages.)-2.5 E/F1 10/Courier@0 SF
(NORM_CMD)54 96 Q 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 are generated by senders of data content, and)2.5 E F1
(NORM_NACK)2.5 E F0(and)2.5 E F1(NORM_ACK)54 108 Q F0
(messages generated by recei)2.5 E -.15(ve)-.25 G
(rs within a NormSession.).15 E(An auxillary message type of NORM_REPOR)
5 E 2.5(Ti)-.6 G 2.5(sa)-2.5 G(lso)-2.5 E(pro)54 120 Q(vided for e)-.15
E(xperimental purposes.)-.15 E
(This section described the message formats used by the NORM protocol.)5
E(These)5 E(messages and their \214elds are referenced in the detailed \
functional description of the NORM protocol gi)54 132 Q -.15(ve)-.25 G
2.5(ni).15 G 2.5(nS)-2.5 G(ection 5.0.)-2.5 E(Indi)54 144 Q(vidual NORM\
 messages are designed to be compatible with the MTU limitations of enc\
apsulating Internet protocols)-.25 E(including IPv4, IPv6, and UDP)54
156 Q 5(.T)-1.11 G(he current NORM protocol speci\214cation assumes UDP\
 encapsulation and le)-5 E -.15(ve)-.25 G(rages the).15 E
(transport features of UDP)54 168 Q 5(.T)-1.11 G
(he NORM messages are independent of netw)-5 E
(ork addresses and can be used in IPv4 and IPv6)-.1 E(netw)54 180 Q
(orks.)-.1 E/F2 10/Times-Bold@0 SF(4.1 NORM Common Message Header)36 204
Q F0(There are some common message \214elds contained in all NORM messa\
ge types.)54 228 Q(All NORM protocol messages be)5 E(gin with a)-.15 E
(common header with information \214elds as follo)54 240 Q(ws:)-.25 E/F3
10/Times-BoldItalic@0 SF(NORM Common Message Header F)54 276 Q(ormat:)
-.7 E F1 114(0123)60 300 S 6(01234567890123456789012345678901)60 312 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
324 Q 24(|v)54 336 S 18(ersion |)-24 F 30(type |)30 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
348 Q 162(|s)54 360 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
372 Q 180(|.)54 384 S 174(.. |)-180 F F0(The "v)54 408 Q
(ersion" \214eld is a 8-bit v)-.15 E(alue indicating the protocol v)-.25
E(ersion number)-.15 E 5(.C)-.55 G(urrently)-5 E 2.5(,N)-.65 G
(ORM implementations SHOULD)-2.5 E(ignore recei)54 420 Q -.15(ve)-.25 G
2.5(dm).15 G(essages with a dif)-2.5 E(ferent protocol v)-.25 E
(ersion number than their o)-.15 E
(wn. This number is intended to indicate and)-.25 E
(distinguish upgrades of the protocol which may be non-interoperable.)54
432 Q(The message "type" \214eld is a 8-bit v)54 456 Q
(alue indicating the NORM protocol message type.)-.25 E
(These types are de\214ned as follo)5 E(ws:)-.25 E 28.005(Message V)
267.82 486 R(alue)-1.11 E 29.055(NORM_INFO 1)252.315 510 R F1(NORM_DATA)
252.315 522 Q F0(2)35.885 E F1(NORM_CMD)252.315 534 Q F0(3)41.885 E F1
(NORM_NACK)252.315 546 Q F0(4)35.885 E F1(NORM_ACK)252.315 558 Q F0(5)
41.885 E F1(NORM_REPORT)252.315 570 Q F0(6)23.885 E
(The "sequence" \214eld is a 16-bit v)54 600 Q(alue that is set by the \
message originator as a monotonically increasing number)-.25 E
(incremented with each NORM message transmitted to the session')54 612 Q
2.5(sd)-.55 G(estination address.)-2.5 E
(The "sequence" \214eld SHOULD not)5 E(be incremented for messages not \
sent to the session group address \(e.g. unicast N)54 624 Q -.4(AC)-.35
G(Ks or unicast A).4 E 2.5(CKs\). This)-.4 F -.25(va)2.5 G(lue can be)
.25 E(monitored by recei)54 636 Q(ving nodes to detect pack)-.25 E
(et losses in the transmission from a sender)-.1 E 5(.N)-.55 G
(ote that this v)-5 E(alue is NO)-.25 E 2.5(Tu)-.4 G(sed in)-2.5 E
(the NORM protocol to detect missing reliable data content and does NO)
54 648 Q 2.5(Ti)-.4 G(dentify the application data or FEC payload that)
-2.5 E(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(may be attached.)54 84 Q
(This sequence number is intended for use in estimating ra)5 E 2.5(wp)
-.15 G(ack)-2.5 E(et loss for congestion control purposes.)-.1 E
(The size of this \214eld is intended to be suf)54 96 Q
(\214cient to allo)-.25 E 2.5(wd)-.25 G
(etection of a reasonable range of pack)-2.5 E
(et loss within the delay-)-.1 E(bandwidth product of e)54 108 Q
(xpected netw)-.15 E(ork connections.)-.1 E
(The "source_id" \214eld is a 32-bit v)54 132 Q
(alue identifying the node that sent the message.)-.25 E 2.5(Ap)5 G
(articipant')-2.5 E 2.5(sN)-.55 G(ORM node identi\214er)-2.5 E
(\(NormNodeId\) can be set according to the application needs b)54 144 Q
(ut unique identi\214ers must be assigned within a single)-.2 E 2.5
(NormSession. In)54 156 R
(some cases, use of the host IP address or a hash of it can suf)2.5 E
(\214ce, b)-.25 E(ut alternati)-.2 E .3 -.15(ve m)-.25 H
(ethodologies for).15 E(assignment and potential collision resolution o\
f node identi\214ers within a multicast session need to be considered.)
54 168 Q -.15(Fo)5 G(r).15 E -.15(ex)54 180 S
(ample, the "source identi\214er" mechanism de\214ned in the Real-T).15
E(ime Protocol \(R)-.35 E
(TP\) speci\214cation [20] may be applicable to)-.6 E
(use for NORM node identi\214ers.)54 192 Q
(At this point in time, the protocol mak)5 E(es no assumptions about ho)
-.1 E 2.5(wt)-.25 G(hese unique identi\214ers)-2.5 E
(are actually assigned.)54 204 Q/F1 10/Times-Bold@0 SF
(4.2 NORM Sender Messages)36 228 Q F0(NORM sender messages include the)
54 252 Q/F2 10/Courier@0 SF(NORM_DATA)2.5 E F0(type, the)2.5 E F2
(NORM_INFO)2.5 E F0(type, and the)2.5 E F2(NORM_CMD)2.5 E F0(type.)2.5 E
F2(NORM_DATA)5 E F0(and)2.5 E F2(NORM_INFO)54 264 Q F0
(messages contain application data content while)2.5 E F2(NORM_CMD)2.5 E
F0(messages for v)2.5 E(arious protocol functions.)-.25 E F1
(4.2.1 NORM_D)54 288 Q -1.5 -.95(AT A)-.35 H(Message)3.45 E F0(The)54
312 Q F2(NORM_DATA)2.5 E F0(message is e)2.5 E
(xpected to be the predominant type transmitted by NORM senders.)-.15 E
(These messages are used)5 E(to encapsulate se)54 324 Q
(gmented data content for objects of type NORM_OBJECT_D)-.15 E -1.21
-1.11(AT A)-.4 H 2.5(,N)1.11 G(ORM_OBJECT_FILE, and)-2.5 E
(NORM_OBJECT_STREAM.)54 336 Q F2(NORM_DATA)5 E F0
(messages may contain original or FEC-encoded application data content.)
2.5 E(The)5 E(payload size of these messages SHALL be limited to a maxi\
mum of the sender')54 348 Q(s)-.55 E/F3 10/Times-Italic@0 SF(NormSe)2.5
E(gmentSize)-.4 E F0 5(.A)C(sender')-2.5 E(s)-.55 E(NormSe)54 360 Q
(gmentSize is assumed to be constant for the duration of a gi)-.15 E
-.15(ve)-.25 G 2.5(ns).15 G(ender')-2.5 E 2.5(st)-.55 G
(erm of participation in the session.)-2.5 E(The)5 E(NormSe)54 372 Q
(gmentSize is e)-.15 E(xpected to be con\214gurable by the sender appli\
cation prior to session participation as needed for)-.15 E(netw)54 384 Q
(ork topology maximum transmission unit \(MTU\) considerations.)-.1 E
-.15(Fo)5 G 2.5(rI).15 G(Pv6, MTU disco)-2.5 E -.15(ve)-.15 G
(ry may be le).15 E -.15(ve)-.25 G(raged at).15 E(session startup)54 396
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-BoldItalic@0 SF(NORM_D)54 84 Q 1.1
-.55(ATA M)-.25 H(essage F).55 E(ormat)-.7 E/F2 10/Courier@0 SF 114
(0123)60 108 S 6(01234567890123456789012345678901)60 120 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
132 Q 24(|v)54 144 S 18(ersion |)-24 F(type = 2)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
156 Q 162(|s)54 168 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
180 Q 30(|f)54 192 S 24(lags | grtt)-30 F 30(|g)36 G 24(size |)-30 F
(fec_id = 129)6 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
204 Q 42(|f)54 216 S 48(ec_instance_id |)-42 F 48(fec_num_parity |)48 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
228 Q 36(|f)54 240 S 42(ec_max_block_len |)-36 F 54(segment_size |)54 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
252 Q 30(|o)54 264 S 36(bject_transport_id |)-30 F(object_size \(msb\))
36 E(|)48 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
276 Q 144(|o)54 288 S(bject_size \(lsb\))-144 E(|)132 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
300 Q 144(|f)54 312 S 132(ec_block_number |)-144 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
324 Q 54(|f)54 336 S 48(ec_block_len | fec_symbol_id |)-54 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
348 Q 60(|p)54 360 S 48(ayload_len* |)-60 F(offset \(msb\)*)60 E(|)48 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
372 Q 156(|o)54 384 S(ffset \(lsb\)*)-156 E(|)144 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
396 Q 156(|p)54 408 S 138(ayload_data* |)-156 F/F3 10/Times-Italic@0 SF
2.5(*Note: The)54 432 R("payload_len" and "of)2.5 E
(fset" \214elds for NORM_D)-.18 E -.37(AT)-.35 G 2.5(Am)-.13 G(essa)-2.5
E -.1(ge)-.1 G 2.5(sc).1 G(ontaining parity information ar)-2.5 E 2.5
(ea)-.37 G(ctually values)-2.5 E(computed fr)54 444 Q
(om FEC encoding of the "payload_len" and "of)-.45 E
(fset" \214elds of the data se)-.18 E
(gments of the applicable coding bloc)-.4 E(k.)-.2 E(So, for parity se)
54 456 Q(gments, these do _not_ r)-.4 E(epr)-.37 E(esent actual values.)
-.37 E -.8(Pa)5 G(rity pac).8 E -.1(ke)-.2 G
(ts can be identi\214ed as pac).1 E -.1(ke)-.2 G(ts wher).1 E(e)-.37 E
("fec_symbol_id >= fec_bloc)54 468 Q(k_len".)-.2 E F0(The "v)54 492 Q(e\
rsion", "type", "sequence", and "source_id" \214elds form the NORM Comm\
on Message Header asdescribed in Section)-.15 E(4.1.)54 504 Q
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(The "\215ags" \214eld contains a number of dif)54
84 Q(ferent binary \215ags pro)-.25 E(viding information and hints re)
-.15 E -.05(ga)-.15 G(rding ho).05 E 2.5(wt)-.25 G(he recei)-2.5 E -.15
(ve)-.25 G(r).15 E(should handle the identi\214ed object.)54 96 Q
(De\214ned \215ags in this \214eld include:)5 E .4 LW 543.825 118.5
64.575 118.5 DL 67.85(Flag V)124.925 128 R 140.39(alue Purpose)-1.11 F
543.825 132.5 64.575 132.5 DL(NORM_FLA)69.575 142 Q(G_REP)-.4 E 42.015
(AIR 0x01)-.92 F(Indicates message is a repair transmission)250.825 142
Q 543.825 146.5 64.575 146.5 DL(NORM_FLA)69.575 156 Q 32.215
(G_EXPLICIT 0x02)-.4 F(Indicates a repair se)250.825 156 Q
(gment intended which meets a speci\214c recei)-.15 E -.15(ve)-.25 G(r)
.15 E(erasure, as compared to parity se)250.825 168 Q(gments pro)-.15 E
(vided by the sender for)-.15 E(general purpose \(with respect to an FE\
C coding block\) erasure \214lling.)250.825 180 Q 543.825 184.5 64.575
184.5 DL(NORM_FLA)69.575 194 Q 53.325(G_INFO 0x04)-.4 F(Indicates a)
250.825 194 Q -.25(va)-.2 G(ilability of).25 E/F1 10/Courier@0 SF
(NORM_INFO)2.5 E F0(for object)2.5 E 543.825 198.5 64.575 198.5 DL
(NORM_FLA)69.575 208 Q 13.885(G_UNRELIABLE 0x08)-.4 F
(Indicates that repair transmissions for the speci\214ed object will be)
250.825 208 Q(una)250.825 220 Q -.25(va)-.2 G
(ilable. \(One-shot, best ef).25 E(fort transmission\))-.25 E 543.825
224.5 64.575 224.5 DL(NORM_FLA)69.575 234 Q 55.545(G_FILE 0x10)-.4 F
(Indicates object is "\214le-based" data \(hint to use disk storage for)
250.825 234 Q(reception\))250.825 246 Q 543.825 250.5 64.575 250.5 DL
(NORM_FLA)69.575 260 Q 36.095(G_STREAM 0x20)-.4 F
(Indicates object is of type NORM_OBJECT_STREAM.)250.825 260 Q 543.825
264.5 64.575 264.5 DL 543.825 118.5 543.825 264.5 DL 64.575 118.5 64.575
264.5 DL 243.325 118.5 243.325 264.5 DL 205.555 118.5 205.555 264.5 DL
(The)54 290 Q F1(NORM_FLAG_REPAIR)2.5 E F0
(\215ag is set when the associated message is a repair transmission.)2.5
E(This information can be used)5 E(by recei)54 302 Q -.15(ve)-.25 G
(rs to help observ).15 E 2.5(eaj)-.15 G(oin polic)-2.5 E 2.5(yw)-.15 G
(here it is desired that ne)-2.5 E(wly joining recei)-.25 E -.15(ve)-.25
G(rs only be).15 E(gin participating in the)-.15 E -.35(NA)54 314 S
(CK process upon receipt of ne)-.05 E 2.5(w\()-.25 G
(non-repair\) data content.)-2.5 E(The)5 E F1(NORM_FLAG_EXPLICIT)2.5 E
F0(\215ag is used to mark repair)2.5 E
(messages sent when the data sender has e)54 326 Q
(xhausted its ability to pro)-.15 E(vide "fresh" \(pre)-.15 E
(viously untransmitted\) parity se)-.25 E(gments as)-.15 E(repair)54 338
Q 5(.T)-.55 G(his \215ag may be used by intermediate systems implementi\
ng Generic Router Assist \(GRA\) functionality to control)-5 E
(subcasting of repair content to dif)54 350 Q(ferent le)-.25 E
(gs of a reliable multicast topology with disparate repair needs. The)
-.15 E F1(NORM_FLAG_INFO)54 362 Q F0
(\215ag is set only when there optional)2.5 E F1(NORM_INFO)2.5 E F0
(content is a)2.5 E -.25(va)-.2 G(ilable for the associated object.).25
E(Thus,)5 E(recei)54 374 Q -.15(ve)-.25 G(rs will N).15 E -.4(AC)-.35 G
2.5(Kf).4 G(or retransmission of)-2.5 E F1(NORM_INFO)2.5 E F0
(only when it is a)2.5 E -.25(va)-.2 G 2.5(ilable. The).25 F F1
(NORM_FLAG_UNRELIABLE)2.5 E F0(\215ag is)2.5 E
(set when the sender wishes to transmit an object with only "best ef)54
386 Q(fort" deli)-.25 E -.15(ve)-.25 G
(ry and will not supply repair transmissions for).15 E(the object.)54
398 Q(The)5 E F1(NORM_FLAG_FILE)2.5 E F0(\215ag can be set as a "hint" \
from the sender that the associated object should be stored in)2.5 E
(non-v)54 410 Q(olatile storage.)-.2 E(The)5 E F1(NORM_FLAG_STREAM)2.5 E
F0(\215ag is set when the identi\214ed object is of type)2.5 E F1
(NORM_OBJECT_STREAM)2.5 E F0(.)A(The "grtt" \214eld contains a non-line\
ar quantized representation of the sender')54 434 Q 2.5(sc)-.55 G
(urrent estimate of group round-trip time)-2.5 E(\(GR)54 446 Q(TT\) \(T\
his is also referred to as R_max in the TFMCC Building Block [18]\).)-.6
E(This v)5 E(alue is used to control timing of the)-.25 E -.35(NA)54 458
S(CK repair process and other aspects of protocol operation as describe\
d in this document.)-.05 E(The algorithm for encoding and)5 E(decoding \
this \214eld is described in the RMT NORM Building Block document[15].)
54 470 Q(The "gsize" \214eld contains a representation of the sender')54
494 Q 2.5(sc)-.55 G(urrent estimate of group size.)-2.5 E(This v)5 E
(alue is used to control)-.25 E(feedback suppression mechanisms within \
the protocol for more optimized performance for dif)54 506 Q
(ferent group sizes.)-.25 E(The 8-bit)5 E("gsize" \214eld consists of 4\
 bits of mantissa in the 4 most signi\214cant bits and 4 bits of base 1\
0 e)54 518 Q(xponent \(order of magnitude\))-.15 E
(information in the 4 least signi\214cant bits.)54 530 Q -.15(Fo)7.5 G
2.5(re).15 G(xample, to represent an approximate group size of 100 \(or\
 1e02\), the v)-2.65 E(alue)-.25 E(of the upper 4 bits is 0x01 \(to rep\
resent the mantissa of 1\) and the lo)54 542 Q(wer 4 bits v)-.25 E
(alue w)-.25 E(ould be 0x02 for an 8-bit)-.1 E
(representation of "0x12". As another e)54 554 Q
(xample, a group size of 9000 \(9e03\) w)-.15 E
(ould be represented by the v)-.1 E(alue 0x93.)-.25 E(The)5 E
(group size does not need to be represented with a high de)54 566 Q
(gree of precision to appropriately scale back)-.15 E(of)-.1 E 2.5(ft)
-.25 G(imers, etc.)-2.5 E(The "fec_id" \214eld corresponds to the FEC E\
ncoding Identi\214er described in the FEC Building Block document [17].)
54 590 Q(Note)5 E(the pack)54 602 Q(et format illustrated abo)-.1 E .3
-.15(ve a)-.15 H(ssumes "Small Block Systematic Codes" that corresponds\
 to an FEC Encoding Identi\214er).15 E(equal to 129.)54 614 Q
(The other "fec_" \214elds may be interpreted or sized dif)5 E
(ferently to supportother FEC Encoding Identi\214er types)-.25 E
(in the future.)54 626 Q(The "fec_instance_id" corresponds to the "FEC \
Instance ID" of the FEC Object T)54 650 Q(ransmission Informatiom gi)
-.35 E -.15(ve)-.25 G 2.5(ni).15 G 2.5(nt)-2.5 G(he FEC)-2.5 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 10])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(Building Block document[17].)54 84 Q
(The "fec_instance_id" SHALL be a v)5 E
(alue corresponding to the particular type of Small)-.25 E(Block System\
atic Code being used \(e.g. Reed-Solomon GF\(2^8\), Reed-Solomon GF\(2^\
16\), etc\).)54 96 Q(The standardized)5 E
(assignment of FEC Instance ID v)54 108 Q(alues is described in [17].)
-.25 E(The "fec_num_parity" corresponds to the "maximum number of of en\
coding symbols that can be generated for an)54 132 Q 2.5(ys)-.15 G
(ource)-2.5 E(block" as described in for FEC Object T)54 144 Q(ransmiss\
ion Information for Small Block Systematic Codes in the FEC Building)
-.35 E(Block document [17].)54 156 Q -.15(Fo)5 G 2.5(re).15 G
(xample, Reed-Solomon codes may be arbitrarily shortened to create dif)
-2.65 E(ferent code v)-.25 E(ariations for)-.25 E 2.5(ag)54 168 S -2.15
-.25(iv e)-2.5 H 2.5(nb).25 G(lock length.)-2.5 E
(In the case of Reed-Solomon \(GF\(2^8\) and GF\(2^16\) codes, this v)5
E(alue indicates the maximum number)-.25 E(of parity se)54 180 Q
(gments a)-.15 E -.25(va)-.2 G
(ilable from the sender for the coding blocks.).25 E(This \214eld MA)5 E
2.5(Yb)-1.05 G 2.5(ei)-2.5 G(nterpreted dif)-2.5 E(ferently for other)
-.25 E(systematic codes as the)54 192 Q 2.5(ya)-.15 G(re de\214ned.)-2.5
E(The "fec_max_block_len" indicates the current maximum number of user \
data se)54 216 Q(gments per FEC coding block to be used by)-.15 E
(the sender during the session.)54 228 Q(This allo)5 E(ws recei)-.25 E
-.15(ve)-.25 G(rs to allocate appropriate b).15 E(uf)-.2 E
(fer space for b)-.25 E(uf)-.2 E(fering blocks transmitted by)-.25 E
(the sender)54 240 Q(.)-.55 E(The "se)54 264 Q
(gment_size" \214eld indicates the sender')-.15 E 2.5(sc)-.55 G
(urrent setting for maximum message payload content \(in bytes\).)-2.5 E
(This)5 E(allo)54 276 Q(ws recei)-.25 E -.15(ve)-.25 G
(rs to allocate appropriate b).15 E(uf)-.2 E(fering resources and to de\
termine other information in order to properly process)-.25 E(recei)54
288 Q -.15(ve)-.25 G 2.5(dd).15 G(ata messaging.)-2.5 E(The "object_tra\
nsport_id" \214eld is a monotonically and incrementally increasing v)54
312 Q(alue assigned by a sender to the object)-.25 E(being transmitted.)
54 324 Q -.35(Tr)5 G(ansmissions and repair requests related to that ob\
ject use the same "object_transport_id" v).35 E 2.5(alue. F)-.25 F(or)
-.15 E(sessions of v)54 336 Q(ery long or inde\214nite duration, the "o\
bject_transport_id" \214eld may be repeated, b)-.15 E
(ut it is presumed that the 16-bit)-.2 E(\214eld size pro)54 348 Q
(vides an adequate enough sequence space to pre)-.15 E -.15(ve)-.25 G
(nt temporary object confusion amongst recei).15 E -.15(ve)-.25 G
(rs and sources).15 E(\(i.e. recei)54 360 Q -.15(ve)-.25 G
(rs SHOULD re-synchronize with a serv).15 E(er when recei)-.15 E
(ving object sequence identi\214ers suf)-.25 E(\214ciently out-of-range)
-.25 E(with the current state k)54 372 Q(ept for a gi)-.1 E -.15(ve)-.25
G 2.5(ns).15 G 2.5(ource\). During)-2.5 F
(the course of its transmission within a NORM session, an object is)2.5
E(uniquely identi\214ed by the concatenation of the sender "node_id" an\
d the gi)54 384 Q -.15(ve)-.25 G 2.5(n").15 G 2.5
(object_transport_id". Note)-2.5 F(that)2.5 E/F1 10/Courier@0 SF
(NORM_INFO)54 396 Q F0(messages associated with the identi\214ed object\
 carry the same "object_transport_id" v)2.5 E(alue.)-.25 E(The 48-bit "\
object_size" \214eld indicates the total size of the object \(in bytes\
\) for the static object types of)54 420 Q F1(NORM_OBJECT_FILE)54 432 Q
F0(and)2.5 E F1(NORM_OBJECT_DATA)2.5 E F0 5(.T)C
(his information is used by recei)-5 E -.15(ve)-.25 G
(rs to determine storage).15 E
(requirements and/or allocate storage for the recei)54 444 Q -.15(ve)
-.25 G 2.5(do).15 G 2.5(bject. Recei)-2.5 F -.15(ve)-.25 G
(rs with insuf).15 E(\214cient storage capability may wish to)-.25 E
(fore)54 456 Q(go reliable reception \(i.e. not N)-.15 E -.4(AC)-.35 G
2.5(Kf).4 G(or\) of the indicated object.)-2.5 E
(In the case of objects of type)5 E F1(NORM_OBJECT_STREAM)54 468 Q F0
2.5(,t)C(he "object_size" \214eld is used to by the sender to indicate \
the size of its stream b)-2.5 E(uf)-.2 E(fer to the)-.25 E(recei)54 480
Q -.15(ve)-.25 G 2.5(rg).15 G 2.5(roup. In)-2.5 F(turn, the recei)2.5 E
-.15(ve)-.25 G(rs SHOULD use this information to allocate a stream b).15
E(uf)-.2 E(fer for reception of)-.25 E(corresponding size.)54 492 Q(The\
 "fec_block_number", "fec_block_len", and "fec_symbol_id" \214elds corr\
espond to the "Source Block Number", "Source)54 516 Q
(Block Length, and "Encoding Symbol ID" \214elds of the FEC P)54 528 Q
(ayload ID format gi)-.15 E -.15(ve)-.25 G 2.5(nb).15 G 2.5(yt)-2.5 G
(he FEC Building Block)-2.5 E 2.5(document[17]. The)54 540 R
("fec_block_number" identi\214es the coding block')2.5 E 2.5(sr)-.55 G
(elati)-2.5 E .3 -.15(ve p)-.25 H(osition with a NormObject.).15 E
(Note that, for)5 E(NormObjects of type NORM_OBJECT_STREAM, the "fec_bl\
ock_number" may wrap for v)54 552 Q(ery long li)-.15 E -.15(ve)-.25 G
2.5(ds).15 G 2.5(essions. The)-2.5 F
("fec_block_len" indicates the number of user data se)54 564 Q
(gments in the identi\214ed coding block.)-.15 E(Gi)5 E -.15(ve)-.25 G
2.5(nt).15 G(he "fec_block_len")-2.5 E
(\(Source block length\) information of ho)54 576 Q 2.5(wm)-.25 G(an)
-2.5 E 2.5(ys)-.15 G
(ymbols of application data is contained in the block, the recei)-2.5 E
-.15(ve)-.25 G 2.5(rc).15 G(an)-2.5 E(determine whether the attached se)
54 588 Q(gment is data or parity content and treat it appropriately)-.15
E 5(.T)-.65 G(he "fec_symbol_id" identi\214es)-5 E
(which speci\214c symbol \(se)54 600 Q
(gment\) within the coding block the attached payload con)-.15 E -.15
(vey)-.4 G 2.5(s. Depending).15 F(upon the v)2.5 E(alue of the)-.25 E("\
fec_symbol_id" and the associated "fec_block_len" and "fec_num_parity" \
parameters for the block, the symbol \(se)54 612 Q(gment\))-.15 E
(referenced may be a user data or an FEC parity se)54 624 Q 2.5
(gment. F)-.15 F(or systematic codes, symbols numbered 0 through)-.15 E
F1(\(fec_block_len-1\))54 636 Q F0(contain application data while se)2.5
E(gments numbered)-.15 E F1(\(fec_block_len\))2.5 E F0(through)2.5 E F1
(\(fec_block_len+fec_num_parity-1\))54 648 Q F0
(contain the parity symbols calculated for the block.)2.5 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 11])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(The concatenation of)54 84 Q/F1 10/Times-Italic@0
SF(object_tr)2.5 E(anport_id::fec_bloc)-.15 E(k_number::fec_symbol_id)
-.2 E F0(can be vie)2.5 E(wed as a unique transport data unit)-.25 E
(\(TPDU\) identi\214er for the attached se)54 96 Q
(gment with respect to the NORM sender)-.15 E(.)-.55 E
(The "payload_len" and "of)54 120 Q
(fset" \214elds are used to identify the relati)-.25 E .3 -.15(ve p)-.25
H(osition and quantity of the content of the message).15 E 2.5
(payload. F)54 132 R(or senders emplo)-.15 E(ying systematic FEC encodi\
ng, these \214elds will correspond to actual length and of)-.1 E(fset v)
-.25 E(alues for)-.25 E/F2 10/Courier@0 SF(NORM_DATA)54 144 Q F0
(messages which contain original data content.)2.5 E -.15(Fo)5 G(r).15 E
F2(NORM_DATA)2.5 E F0(messages containing calculated parity)2.5 E
(content, these \214elds will actually contain v)54 156 Q
(alues computed by FEC encoding of the "payload_len" and "of)-.25 E
(fset" v)-.25 E(alues of the)-.25 E F2(NORM_DATA)54 168 Q F0(se)2.5 E
(gments of the corresponding FEC coding block.)-.15 E
(Thus, the "payload_len" and "of)5 E(fset" v)-.25 E
(alues of missing data)-.25 E
(content can be determined when decoding an FEC coding block.)54 180 Q(\
The "payload_data" \214eld contains original data or computed parity co\
ntent of the identi\214ed se)54 204 Q 2.5(gment. The)-.15 F
(maximum length)2.5 E(of this \214eld corresponds to the sender')54 216
Q 2.5(sN)-.55 G(ormSe)-2.5 E 2.5(gmentSize. The)-.15 F
(length of this \214eld for messages containing parity content)2.5 E
(will al)54 228 Q -.1(wa)-.1 G(ys be of the length NormSe).1 E 2.5
(gmentSize. When)-.15 F(encoding data se)2.5 E(gments of v)-.15 E
(arying sizes, the FEC encoder SHALL)-.25 E(assume zero v)54 240 Q
(alue padding for data se)-.25 E
(gments with length less than the NormSe)-.15 E 2.5(gmentSize. The)-.15
F(recei)2.5 E -.15(ve)-.25 G 2.5(rw).15 G(ill use the)-2.5 E
("payload_len" information to properly retrie)54 252 Q .3 -.15(ve r)-.25
H(ecei).15 E -.15(ve)-.25 G 2.5(dd).15 G(ata content and deli)-2.5 E
-.15(ve)-.25 G 2.5(ri).15 G 2.5(tt)-2.5 G 2.5(ot)-2.5 G(he application.)
-2.5 E/F3 10/Times-Bold@0 SF(4.2.2 NORM_INFO Message)54 276 Q F0(The)54
300 Q F2(NORM_INFO)2.5 E F0(message is used to con)2.5 E .3 -.15(vey O)
-.4 H(PTION).15 E(AL, application-de\214ned, "out-of-band" conte)-.35 E
(xt information for)-.15 E(transmitted NormObjects.)54 312 Q(An e)5 E
(xample)-.15 E F2(NORM_INFO)2.5 E F0(use for b)2.5 E
(ulk \214le transfer is to place MIME type information for the)-.2 E
(associated \214le, data, or stream object into the)54 324 Q F2
(NORM_INFO)2.5 E F0 2.5(payload. Recei)2.5 F -.15(ve)-.25 G
(rs may use the).15 E F2(NORM_INFO)2.5 E F0(content to mak)2.5 E 2.5(ea)
-.1 G(decision as whether to participate in reliable reception of the a\
ssociated object.)54 336 Q(Each NormObject can ha)5 E .3 -.15(ve a)-.2 H
2.5(ni).15 G(ndependent)-2.5 E(unit of)54 348 Q F2(NORM_INFO)2.5 E F0
(associated with it.)2.5 E F2(NORM_DATA)5 E F0
(messages contain a \215ag to indicate the a)2.5 E -.25(va)-.2 G
(ilability of).25 E F2(NORM_INFO)2.5 E F0(for a gi)54 360 Q -.15(ve)-.25
G 2.5(nN).15 G 2.5(ormObject. NORM)-2.5 F(recei)2.5 E -.15(ve)-.25 G
(rs may N).15 E -.4(AC)-.35 G 2.5(Kf).4 G(or retransmission of)-2.5 E F2
(NORM_INFO)2.5 E F0(when the)2.5 E 2.5(yh)-.15 G -2.25 -.2(av e)-2.5 H
(not recei)2.7 E -.15(ve)-.25 G 2.5(di).15 G(t)-2.5 E(for a gi)54 372 Q
-.15(ve)-.25 G 2.5(nN).15 G 2.5(ormObject. The)-2.5 F(size of the)2.5 E
F2(NORM_INFO)2.5 E F0(content is limited to that of a single NormSe)2.5
E(gmentSize for the gi)-.15 E -.15(ve)-.25 G(n).15 E(sender)54 384 Q 5
(.T)-.55 G(his atomic nature allo)-5 E(ws the)-.25 E F2(NORM_INFO)2.5 E
F0(to be rapidly and ef)2.5 E
(\214ciently repaired within the NORM reliable)-.25 E
(transmission process.)54 396 Q(When)54 420 Q F2(NORM_INFO)2.5 E F0
(content is a)2.5 E -.25(va)-.2 G(ilable for a NormObject, the NORM_FLA)
.25 E(G_INFO \215ag SHALL be set in)-.4 E F2(NORM_DATA)2.5 E F0
(messages for the corresponding "object_transport_id" and the)54 432 Q
F2(NORM_INFO)2.5 E F0
(message shall be transmitted as the \214rst message)2.5 E
(for the NormObject.)54 444 Q(Adamson, Borman, et al.)36 696 Q
(Expires September 2003)110.05 E([P)118.25 E(age 12])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-BoldItalic@0 SF(NORM_INFO Message F)54
84 Q(ormat)-.7 E/F2 10/Courier@0 SF 114(0123)60 108 S 6
(01234567890123456789012345678901)60 120 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
132 Q 24(|v)54 144 S 18(ersion |)-24 F(type = 1)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
156 Q 162(|s)54 168 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
180 Q 30(|f)54 192 S 24(lags | grtt)-30 F 30(|g)36 G 24(size |)-30 F
(fec_id = 129)6 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
204 Q 42(|f)54 216 S 36(ec_encoding_name |)-42 F 42(fec_num_parity |)54
F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
228 Q 42(|f)54 240 S 36(ec_max_block_len |)-42 F 48(segment_size |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
252 Q 36(|o)54 264 S 30(bject_transport_id |)-36 F(object_size \(msb\))
48 E(|)36 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
276 Q 144(|o)54 288 S(bject_size \(lsb\))-144 E(|)132 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
300 Q 150(|p)54 312 S 150(ayload_data |)-150 F F0(The "v)54 336 Q(ersio\
n", "type", "sequence", and "source_id" \214elds form the NORM Common M\
essage Header asdescribed in Section)-.15 E(4.1.)54 348 Q(The "\215ags"\
, "grtt", "gsize", "fec_id", "fec_encoding_name", "fec_num_parity", "fe\
c_max_block_len", "se)54 372 Q(gment_size",)-.15 E("object_transport_id\
", and "object_size" \214elds carry the same information and serv)54 384
Q 2.5(et)-.15 G(he same purpose as with)-2.5 E F2(NORM_DATA)2.5 E F0 2.5
(messages. These)54 396 R -.25(va)2.5 G(lues allo).25 E 2.5(wt)-.25 G
(he recei)-2.5 E -.15(ve)-.25 G 2.5(rt).15 G 2.5(op)-2.5 G
(repare appropriate b)-2.5 E(uf)-.2 E
(fering, etc, for further transmissions from the sender)-.25 E(when)54
408 Q F2(NORM_INFO)2.5 E F0(is the \214rst message recei)2.5 E -.15(ve)
-.25 G(d.).15 E(The)54 432 Q F2(NORM_INFO)2.5 E F0("payload_data" \214e\
ld contains sender application-de\214ned content which can be used by r\
ecei)2.5 E -.15(ve)-.25 G(r).15 E(applications for v)54 444 Q
(arious purposes as described abo)-.25 E -.15(ve)-.15 G(.).15 E/F3 10
/Times-Bold@0 SF(4.2.3 NORM_CMD Message)54 468 Q F2(NORM_CMD)54 492 Q F0
(messages are transmitted by senders to perform a number of dif)2.5 E
(ferent protocol functions.)-.25 E(This includes)5 E(functions such as \
round-trip timing collection, congestion control functions, synchroniza\
tion of sender/recei)54 504 Q -.15(ve)-.25 G 2.5(rr).15 G(epair)-2.5 E
("windo)54 516 Q(ws", and noti\214cation of sender status.)-.25 E 2.5
(Ac)5 G(ore set of)-2.5 E F2(NORM_CMD)2.5 E F0(messages is enumerated.)
2.5 E(Additionally)5 E 2.5(,ar)-.65 G(ange of)-2.5 E
(command types remain a)54 528 Q -.25(va)-.2 G
(ilable for potential application-speci\214c use.).25 E(Some)5 E F2
(NORM_CMD)2.5 E F0(types may ha)2.5 E .3 -.15(ve d)-.2 H(ynamic content)
.15 E 2.5(attached. An)54 540 R 2.5(ya)-.15 G
(ttached content will be limited to maximum length of the sender NormSe)
-2.5 E(gmentSize to retain the atomic)-.15 E(nature of commands.)54 552
Q(All)5 E F2(NORM_CMD)2.5 E F0(message be)2.5 E(gins with a common set \
of \214elds, after the usual NORM message common)-.15 E(header)54 564 Q
5(.T)-.55 G(he standard)-5 E F2(NORM_CMD)2.5 E F0(\214elds are:)2.5 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 13])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-BoldItalic@0 SF(NORM_CMD Standard F)54
84 Q(ields)-.4 E/F2 10/Courier@0 SF 114(0123)60 108 S 6
(01234567890123456789012345678901)60 120 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
132 Q 24(|v)54 144 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
156 Q 162(|s)54 168 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
180 Q 36(|g)54 192 S 24(rtt | gsize |)-36 F 24(flavor |)24 F(...)54 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
204 Q F0(The "v)54 228 Q(ersion", "type", "sequence", and "source_id" \
\214elds form the NORM Common Message Header as described in)-.15 E
(Section 4.1.)54 240 Q(The "grtt" and "gsize" \214elds pro)54 264 Q
(vide the same information and serv)-.15 E 2.5(et)-.15 G
(he same purpose as with)-2.5 E F2(NORM_DATA)2.5 E F0(and)2.5 E F2
(NORM_INFO)54 276 Q F0 2.5(messages. The)2.5 F("\215a)2.5 E -.2(vo)-.2 G
(r" \214eld indicates the type of command to follo).2 E 3.8 -.65(w. T)
-.25 H(he remainder of the).65 E F2(NORM_CMD)2.5 E F0
(message is dependent upon the command type \("\215a)54 288 Q -.2(vo)-.2
G 2.5(r"\). The).2 F(command \215a)2.5 E -.2(vo)-.2 G(rs include:).2 E
.4 LW 526.24 310.5 82.16 310.5 DL 51.215(Command Fla)125.875 320 R -.2
(vo)-.2 G 2.5(rV).2 G 109.64(alue Purpose)-3.61 F 526.24 324.5 82.16
324.5 DL F2(NORM_CMD)87.16 334 Q F0 68.26(\(FLUSH\) 1)B
(Used to indicate sender temporary or permanent end-of-)287.24 334 Q 2.5
(transmission. \(Assists)287.24 346 R(in rob)2.5 E
(ustly initiating outstanding)-.2 E(repair requests from recei)287.24
358 Q -.15(ve)-.25 G(rs\).).15 E 526.24 362.5 82.16 362.5 DL F2
(NORM_CMD)87.16 372 Q F0(\(SQ)A 53.92(UELCH\) 2)-.1 F(Used to adv)287.24
372 Q(ertise sender')-.15 E 2.5(sc)-.55 G(urrent repair windo)-2.5 E 2.5
(wi)-.25 G(n)-2.5 E(response to out-of-range N)287.24 384 Q -.4(AC)-.35
G(Ks from recei).4 E -.15(ve)-.25 G(rs.).15 E 526.24 388.5 82.16 388.5
DL F2(NORM_CMD)87.16 398 Q F0(\(A)A 54.22(CK_REQ\) 3)-.4 F
(Used to request positi)287.24 398 Q .3 -.15(ve a)-.25 H(ckno).15 E
(wledgement from a list of)-.25 E(recei)287.24 410 Q -.15(ve)-.25 G(rs.)
.15 E 526.24 414.5 82.16 414.5 DL F2(NORM_CMD)87.16 424 Q F0(\(REP)A
(AIR_AD)-.92 E 39.03(V\) 4)-.4 F(USed to adv)287.24 424 Q
(ertise sender')-.15 E 2.5(sa)-.55 G(ggre)-2.5 E -.05(ga)-.15 G
(ted repair state for).05 E(suppression of unicast recei)287.24 436 Q
-.15(ve)-.25 G 2.5(rf).15 G(eedback.)-2.5 E 526.24 440.5 82.16 440.5 DL
F2(NORM_CMD)87.16 450 Q F0 86.59(\(CC\) 5)B(Used for GR)287.24 450 Q
(TT measurement and e)-.6 E(xplicitly collection of)-.15 E
(congestion control feedback.)287.24 462 Q 526.24 466.5 82.16 466.5 DL
F2(NORM_CMD)87.16 476 Q F0(\(APPLICA)A 35.49(TION\) 6)-1.11 F
(Used for application-de\214ned purposes which may need to)287.24 476 Q
(temporarily preempt data transmission.)287.24 488 Q 526.24 492.5 82.16
492.5 DL 526.24 310.5 526.24 492.5 DL 82.16 310.5 82.16 492.5 DL 279.74
310.5 279.74 492.5 DL 213.76 310.5 213.76 492.5 DL F1
(NORM_CMD\(FLUSH\) Message)54 518 Q F0(The)54 542 Q F2(NORM_CMD)2.5 E F0
(\(FLUSH\) command is sent when the sender reaches the end of all data \
content and pending repairs it has)A(queued for transmission.)54 554 Q
(This command is repeated once per 2*GR)5 E(TT to e)-.6 E
(xcite the recei)-.15 E -.15(ve)-.25 G 2.5(rs).15 G(et for an)-2.5 E 2.5
(yo)-.15 G(utstanding repair)-2.5 E(requests up to and including the tr\
ansmission point indicated within the)54 566 Q F2(NORM_CMD)2.5 E F0
(\(FLUSH\) message.)A(The number of)5 E(repeats is equal to)54 578 Q F2
(NORM_ROBUST_FACTOR)2.5 E F0 5(.T)C(he greater the)-5 E F2
(NORM_ROBUST_FACTOR)2.5 E F0 2.5(,t)C
(he greater the probability that all)-2.5 E(applicable recei)54 590 Q
-.15(ve)-.25 G(rs will be e).15 E(xcited for repair requests \(N)-.15 E
-.4(AC)-.35 G(Ks\) _and_ that the corresponding N).4 E -.4(AC)-.35 G
(Ks are deli).4 E -.15(ve)-.25 G(red to the).15 E(sender)54 602 Q 5(.I)
-.55 G 2.5(fa)-5 G F2(NORM_NACK)A F0(message interrupts its \215ush pro\
cess, the sender will re-initiate the \215ush process when an)2.5 E 2.5
(yr)-.15 G(esulting)-2.5 E(repair transmissions are completed.)54 614 Q
(Note that recei)5 E -.15(ve)-.25 G(rs also emplo).15 E 2.5(yat)-.1 G
(imeout mechanism to self-initiate N)-2.5 E -.4(AC)-.35 G(King when no)
.4 E(messages are recei)54 626 Q -.15(ve)-.25 G 2.5(df).15 G
(rom a sender)-2.5 E 5(.T)-.55 G(his inacti)-5 E
(vity timeout is related to)-.25 E F2(2*GRTT*NORM_ROBUST_FACTOR)2.5 E F0
(and will be)2.5 E(discussed more later)54 638 Q 5(.W)-.55 G(ith a suf)
-5.4 E(\214cient)-.25 E F2(NORM_ROBUST_FACTOR)2.5 E F0 -.25(va)2.5 G
(lue, data content is deli).25 E -.15(ve)-.25 G
(red with a high assurance of).15 E(reliability)54 650 Q 5(.T)-.65 G
(he penalty of a lar)-5 E(ge)-.18 E F2(NORM_ROBUST_FACTOR)2.5 E F0 -.25
(va)2.5 G(lue is potentially e).25 E(xcess sender)-.15 E F2(NORM_CMD)2.5
E F0(\(FLUSH\))A(Adamson, Borman, et al.)36 696 Q
(Expires September 2003)110.05 E([P)118.25 E(age 14])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(transmissions and a longer timeout for recei)54 84
Q -.15(ve)-.25 G(rs to self-initiate the terminal N).15 E -.4(AC)-.35 G
2.5(Kp).4 G(rocess.)-2.5 E -.15(Fo)54 108 S 2.5<728c>.15 G
(nite-size transport objects such)-2.5 E/F1 10/Courier@0 SF
(NORM_OBJECT_DATA)2.5 E F0(and)2.5 E F1(NORM_OBJECT_FILE)2.5 E F0 2.5
(,t)C(he \215ush process \(if there are no)-2.5 E(further pending trans\
missions\) will occur at the end of these objects and thus an)54 120 Q
2.5(yF)-.15 G(EC repair information is a)-2.5 E -.25(va)-.2 G
(ilable for).25 E(repairs in response to repair requests elicited by th\
e \215ush command.)54 132 Q(Ho)5 E(we)-.25 E -.15(ve)-.25 G .8 -.4(r, f)
.15 H(or).4 E F1(NORM_OBJECT_STREAM)2.5 E F0 2.5(,t)C(he \215ush may)
-2.5 E(occur at an)54 144 Q 2.5(yt)-.15 G(ime, including in the middle \
of an FEC coding block if systematic FEC codes are emplyed.)-2.5 E
(In this case, the)5 E(sender will not yet be able to pro)54 156 Q(vide\
 FEC parity content as repair for the concurrent coding block and will \
be limited to)-.15 E -.15(ex)54 168 S
(plicitly repairing stream data content for that block.).15 E
(Applications that anticipate frequent \215ushing of stream content)5 E
(SHOULD be judicious in the selection of the FEC coding block size \(i.\
e. do not use a v)54 180 Q(ery lar)-.15 E(ge coding block size if)-.18 E
(frequent \215ushing occurs\).)54 192 Q -.15(Fo)5 G 2.5(re).15 G(xample\
, a reliable multicast application transmitting an on-going series of i\
ntermittent,)-2.65 E(relati)54 204 Q -.15(ve)-.25 G
(ly small messaging content will need to trade-of).15 E 2.5(fu)-.25 G
(sing the)-2.5 E F1(NORM_OBJECT_DATA)5 E F0(paradigm v)2.5 E(ersus the)
-.15 E F1(NORM_OBJECT_STREAM)54 216 Q F0
(paradigm with an appropriate FEC coding block size.)2.5 E
(This is analogous to application trade-of)5 E(fs)-.25 E
(for other transport protocols such as the selection of dif)54 228 Q
(ferent TCP modes of operation such as "no delay", etc.)-.25 E/F2 10
/Times-BoldItalic@0 SF(NORM_CMD\(FLUSH\) Message F)54 252 Q(ormat)-.7 E
F1 114(0123)60 276 S 6(01234567890123456789012345678901)60 288 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
300 Q 24(|v)54 312 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
324 Q 162(|s)54 336 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
348 Q 36(|g)54 360 S 24(rtt |)-36 F 18(gsize |)36 F(flavor = 1 |)12 E 30
(flags |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
372 Q 36(|o)54 384 S 30(bject_transport_id |)-36 F
(fec_block_number \(msb\))24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
396 Q 30(|f)54 408 S(ec_block_number \(lsb\))-30 E 48(|f)24 G 54
(ec_symbol_id |)-48 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
420 Q F0(In addition to the NORM common message header and standard)54
444 Q F1(NORM_CMD)2.5 E F0(\214elds, the)2.5 E F1(NORM_CMD)2.5 E F0
(\(FLUSH\) message)A(contains \214elds to identify the current status a\
nd logical transmit position of the sender)54 456 Q(.)-.55 E
(The "\215ags" \214eld contains sender status information.)54 480 Q 2.5
(As)5 G(ingle)-2.5 E F1(NORM_CMD)2.5 E F0
(\(FLUSH\) \215ag is currently de\214ned:)A F1
(NORM_FLUSH_FLAG_EOT = 0x01)226.2 504 Q F0(When the)54 528 Q F1
(NORM_FLUSH_FLAG_EOT)2.5 E F0(\215ag is set, this indicates the sender \
is preparing to terminate transmission and will no)2.5 E(longer pro)54
540 Q(vide response to repair requests.)-.15 E(This allo)5 E
(ws the recei)-.25 E -.15(ve)-.25 G 2.5(rs).15 G
(et to gracefully reach closure of operation with this)-2.5 E
(sender and free an)54 552 Q 2.5(yr)-.15 G
(esources that are no longer needed.)-2.5 E(The "object_transport_id", \
"fec_block_number", and "fec_symbol_id" \214elds indicate the sender')54
576 Q 2.5(sc)-.55 G(urrent logical "transmit)-2.5 E 2.5
(position". These)54 588 R(\214elds are interpreted in the same manner \
as the \214elds of the same names in the)2.5 E F1(NORM_DATA)2.5 E F0
(message type.)2.5 E(Upon receipt of the the)54 600 Q F1(NORM_CMD)2.5 E
F0(\(FLUSH\), recei)A -.15(ve)-.25 G(rs are e).15 E
(xpected to check their completion state _through_ \(including\))-.15 E
(this transmission position.)54 612 Q(If recei)5 E -.15(ve)-.25 G(rs ha)
.15 E .3 -.15(ve o)-.2 H(utstanding repair needs in this range, the).15
E 2.5(yS)-.15 G(HALL initiate the NORM N)-2.5 E -.4(AC)-.35 G(K).4 E
(Repair Process as described in Section 5.3.)54 624 Q(If recei)5 E -.15
(ve)-.25 G(rs ha).15 E .3 -.15(ve n)-.2 H 2.5(oo).15 G
(utstanding repair needs, no response is generated.)-2.5 E -.15(Fo)54
648 S(r).15 E F1(NORM_OBJECT_STREAM)2.5 E F0(objects, recei)2.5 E -.15
(ve)-.25 G(rs MUST request "e).15 E
(xplicit-only" repair of the identi\214ed "fec_block_number")-.15 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 15])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(if the gi)54 84 Q -.15(ve)-.25 G 2.5(n").15 G
(fec_symbol_id" is less than the sender')-2.5 E 2.5(s")-.55 G
(fec_max_block_len - 1".)-2.5 E
(This condition indicates the sender has not)5 E(yet completed encoding\
 the corresponding FEC block and parity content is not yet a)54 96 Q
-.25(va)-.2 G 2.5(ilable. An).25 F("e)2.5 E(xplicit-only" repair)-.15 E
(request consists of N)54 108 Q -.4(AC)-.35 G 2.5(Kc).4 G
(ontent for the applicable "fec_block_number" which does not include an)
-2.5 E 2.5(yr)-.15 G(equests for parity-)-2.5 E(based repair)54 120 Q 5
(.T)-.55 G(his allo)-5 E(ws NORM sender applications to "\215ush" an on\
going stream of transmission when needed, e)-.25 E -.15(ve)-.25 G 2.5
(ni).15 G 2.5(fi)-2.5 G(n)-2.5 E(the middle of an FEC block.)54 132 Q(O\
nce the sender resumes stream transmission and passes the end of the pe\
nding coding block,)5 E(subsequent N)54 144 Q -.4(AC)-.35 G
(Ks from recei).4 E -.15(ve)-.25 G
(rs SHALL request parity-based repair as normal.).15 E
(Note that the use of a systematic FEC)5 E(code is assumed here.)54 156
Q(Normal recei)5 E -.15(ve)-.25 G 2.5(rN).15 G -.4(AC)-2.85 G 2.5(Ki).4
G(nititation and construction is discussed in detail in Section 5.3.)
-2.5 E/F1 10/Times-BoldItalic@0 SF(NORM_CMD\(SQ)54 180 Q
(UELCH\) Message)-.1 E F0(The)54 204 Q/F2 10/Courier@0 SF(NORM_CMD)2.5 E
F0(\(SQ)A(UELCH\) command is transmitted in response to in)-.1 E -.25
(va)-.4 G(lid).25 E F2(NORM_NACK)2.5 E F0(content recei)2.5 E -.15(ve)
-.25 G 2.5(db).15 G 2.5(yt)-2.5 G(he sender)-2.5 E(.)-.55 E(In)54 216 Q
-.25(va)-.4 G(lid).25 E F2(NORM_NACK)2.5 E F0(content consists of repai\
r requests for NormObjects for which the sender is unable or unwilling \
to)2.5 E(pro)54 228 Q(vide repair)-.15 E 5(.T)-.55 G(his includes repai\
r requests for outdated objects, aborted objects, or those objects whic\
h the sender)-5 E(pre)54 240 Q(viously transmitted mark)-.25 E
(ed with the NORM_FLA)-.1 E(G_UNRELIABLE \215ag.)-.4 E
(This command indicates to recei)5 E -.15(ve)-.25 G(rs what).15 E
(content is a)54 252 Q -.25(va)-.2 G(ilable for repair).25 E 2.5(,t)-.4
G(hus serving as a description of the sender')-2.5 E 2.5(sc)-.55 G
(urrent "repair windo)-2.5 E 2.5(w". Recei)-.25 F -.15(ve)-.25 G
(rs SHALL not).15 E
(generate repair requests for content identi\214ed as in)54 264 Q -.25
(va)-.4 G(lid by a).25 E F2(NORM_CMD)2.5 E F0(\(SQ)A(UELCH\).)-.1 E(The)
54 288 Q F2(NORM_CMD)2.5 E F0(\(SQ)A
(UELCH\) command is sent once per 2*GR)-.1 E(TT at the most.)-.6 E(The)5
E F2(NORM_CMD)2.5 E F0(\(SQ)A(UELCH\) adv)-.1 E(ertises the)-.15 E
(current "repair windo)54 300 Q
(w" of the sender by identifying the earliest \(lo)-.25 E
(west\) transmission point for which it will pro)-.25 E(vide repair)-.15
E(,)-.4 E(along with an encoded list of objects from that point forw)54
312 Q(ard that are no longer v)-.1 E(alid for repair)-.25 E 5(.T)-.55 G
(his mechanism allo)-5 E(ws the)-.25 E(sender application to cancel or \
abort transmission and/or repair of pre)54 324 Q
(viously enqueued objects.)-.25 E(The list also contains the)5 E
(identi\214ers for an)54 336 Q 2.5(yo)-.15 G
(bjects within the repair windo)-2.5 E 2.5(ww)-.25 G
(hich were sent with the)-2.5 E F2(NORM_FLAG_UNRELIABLE)2.5 E F0
(\215ag set.)2.5 E(In)5 E(normal conditions, it is e)54 348 Q
(xpected the)-.15 E F2(NORM_CMD)2.5 E F0(\(SQ)A
(UELCH\) will be needed infrequently)-.1 E 2.5(,a)-.65 G
(nd generally only to pro)-2.5 E(vide a)-.15 E(reference repair windo)54
360 Q 2.5(wf)-.25 G(or recei)-2.5 E -.15(ve)-.25 G(rs who ha).15 E .3
-.15(ve f)-.2 H(allen "out-of-sync" with the sender due to e).05 E
(xtremely poor netw)-.15 E(ork)-.1 E(conditions.)54 372 Q
(The starting point of the in)54 396 Q -.25(va)-.4 G
(lid NormObject list be).25 E(gins with the lo)-.15 E(west in)-.25 E
-.25(va)-.4 G(lid NormT).25 E(ransportId greater than the current)-.35 E
("repair windo)54 408 Q(w" start from the in)-.25 E -.25(va)-.4 G(lid N)
.25 E -.4(AC)-.35 G(K\(s\) that prompted the generation of the squelch.)
.4 E(The length of the list is limited)5 E(by the sender')54 420 Q 2.5
(sN)-.55 G(ormSe)-2.5 E 2.5(gmentSize. This)-.15 F(allo)2.5 E
(ws the recei)-.25 E -.15(ve)-.25 G
(rs to learn the status of the sender').15 E 2.5(sa)-.55 G
(pplicable object repair)-2.5 E(windo)54 432 Q 2.5(ww)-.25 G
(ith minimal transmission of)-2.5 E F2(NORM_CMD)2.5 E F0(\(SQ)A
(UELCH\) commands.)-.1 E(The format of the)5 E F2(NORM_CMD)2.5 E F0
(\(SQ)A(UELCH\))-.1 E(message is:)54 444 Q(Adamson, Borman, et al.)36
696 Q(Expires September 2003)110.05 E([P)118.25 E(age 16])-.15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-BoldItalic@0 SF(NORM_CMD\(SQ)54 84 Q
(UELCH\) Message F)-.1 E(ormat)-.7 E/F2 10/Courier@0 SF 114(0123)60 108
S 6(01234567890123456789012345678901)60 120 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
132 Q 24(|v)54 144 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
156 Q 162(|s)54 168 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
180 Q 36(|g)54 192 S 24(rtt | gsize |)-36 F(flavor = 2)12 E 24(|r)18 G
12(eserved |)-24 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
204 Q 36(|o)54 216 S 30(bject_transport_id |)-36 F
(fec_block_number \(msb\))24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
228 Q 30(|f)54 240 S(ec_block_number \(lsb\))-30 E 48(|f)24 G 54
(ec_symbol_id |)-48 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
252 Q 144(|i)54 264 S 6(nvalid_object_list ...)-144 F(|)90 E F0
(In addition to the NORM common message header and standard)54 288 Q F2
(NORM_CMD)2.5 E F0(\214elds, the)2.5 E F2(NORM_CMD)2.5 E F0(\(SQ)A
(UELCH\) message)-.1 E(contains \214elds to identify the earliest logic\
al transmit position of the sender')54 300 Q 2.5(sc)-.55 G
(urrent repair windo)-2.5 E 2.5(wa)-.25 G(nd an "in)-2.5 E -.25(va)-.4 G
(lid object).25 E(list" be)54 312 Q(ginning with the inde)-.15 E 2.5(xo)
-.15 G 2.5(ft)-2.5 G(he logically earliest in)-2.5 E -.25(va)-.4 G
(lid repair request from the of).25 E(fending N)-.25 E -.4(AC)-.35 G 2.5
(Km).4 G(essage which)-2.5 E(initiated the squelch transmission.)54 324
Q(The "object_transport_id", "fec_block_number", and "fec_symbol_id" \
\214elds are concatenated to indicate the be)54 348 Q(ginning of)-.15 E
(the sender')54 360 Q 2.5(sc)-.55 G(urrent repair windo)-2.5 E 2.5(w\()
-.25 G(i.e. the logically earliest point in its transmission history fo\
r which the sender can)-2.5 E(pro)54 372 Q(vide repair\).)-.15 E
(This serv)5 E(es as an adv)-.15 E
(ertisement of a "synchronization point" for recei)-.15 E -.15(ve)-.25 G
(rs to request repair).15 E 5(.N)-.55 G(ote, that while)-5 E
(the "fec_symbol_id" is pro)54 384 Q(vided here, the sender')-.15 E 2.5
(sr)-.55 G(epair windo)-2.5 E 2.5(ww)-.25 G
(ill generally be incremented on an FEC coding block)-2.5 E
(basis and the "fec_symbol_id" will be zero.)54 396 Q(The "in)54 420 Q
-.25(va)-.4 G(lid_object_list" is a list of 16-bit NormT).25 E
(ransportIds that, although the)-.35 E 2.5(ya)-.15 G
(re within the sender')-2.5 E 2.5(sc)-.55 G(urrent repair)-2.5 E(windo)
54 432 Q 1.3 -.65(w, a)-.25 H(re no longer a).65 E -.25(va)-.2 G
(ilable for repair from the sender).25 E 2.5(.F)-.55 G(or e)-2.65 E
(xample, a sender application may dequeue an out-of-date)-.15 E
(object e)54 444 Q -.15(ve)-.25 G 2.5(nt).15 G
(hough it is still within the repair windo)-2.5 E 3.8 -.65(w. T)-.25 H
(he total size of the "in).65 E -.25(va)-.4 G
(lid_object_list" content is implied by the).25 E(pack)54 456 Q
(ets payload length and is limited to a maximum of the NormSe)-.1 E
(gmentSize of the sender)-.15 E 5(.T)-.55 G(hus, for v)-5 E(ery lar)-.15
E(ge repair)-.18 E(windo)54 468 Q(ws, it is possible that a single)-.25
E F2(NORM_CMD)2.5 E F0(\(SQ)A
(UELCH\) message may not be capable of listing the entire set of in)-.1
E -.25(va)-.4 G(lid).25 E(objects in the repair windo)54 480 Q 3.8 -.65
(w. I)-.25 H 2.5(nt).65 G
(his case, the sender SHALL ensure that the list be)-2.5 E
(gins with a NormObjectId that is greater)-.15 E
(than or equal to the lo)54 492 Q(west ordinal in)-.25 E -.25(va)-.4 G
(lid NormObjectId from the N).25 E -.4(AC)-.35 G 2.5(Km).4 G
(essage\(s\) that prompted the)-2.5 E F2(NORM_CMD)54 504 Q F0(\(SQ)A
(UELCH\) generation.)-.1 E(The NormObjectIds in the "in)5 E -.25(va)-.4
G(lid_object_list" must be greater than the).25 E
("object_transport_id" marking the be)54 516 Q(ginning of the sender')
-.15 E 2.5(sr)-.55 G(epair windo)-2.5 E 3.8 -.65(w. T)-.25 H
(his insures con).65 E -.15(ve)-.4 G -.18(rg).15 G(ence of the squelch)
.18 E(process, e)54 528 Q -.15(ve)-.25 G 2.5(ni).15 G 2.5(fm)-2.5 G
(ultiple in)-2.5 E -.25(va)-.4 G(lid N).25 E -.4(AC)-.35 G
(K/ squelch iterations are required.).4 E(This e)5 E
(xplicit description of in)-.15 E -.25(va)-.4 G(lid content within).25 E
(the sender')54 540 Q 2.5(sc)-.55 G(urrent windo)-2.5 E 2.5(wa)-.25 G
(llo)-2.5 E(ws the sender application \(most notably for discrete "obje\
ct" based transport\) to arbitrarily)-.25 E(in)54 552 Q -.25(va)-.4 G(l\
idate \(i.e. dequeue\) portions of enqueued content \(e.g. certain obje\
cts\) for which it no longer wishes to pro).25 E(vide reliable)-.15 E
(transport.)54 564 Q F1(NORM_CMD\(REP)54 588 Q(AIR_AD)-.85 E
(V\) Message)-.5 E F0(The)54 612 Q F2(NORM_CMD)2.5 E F0(\(REP)A(AIR_AD)
-.92 E(V\) message is used by the sender to "adv)-.4 E
(ertise" its aggre)-.15 E -.05(ga)-.15 G
(ted repair state from accumulated).05 E F2(NORM_NACK)54 624 Q F0
(messages accumulated during a repair c)2.5 E
(ycle and/or congestion control feedback recei)-.15 E -.15(ve)-.25 G 2.5
(d. This).15 F(message is)2.5 E(sent only when the sender has recei)54
636 Q -.15(ve)-.25 G(d).15 E F2(NORM_NACK)2.5 E F0(and/or)2.5 E F2
(NORM_ACK)2.5 E F0(\(R)A(TT\) \(when congestion control is enabled\))-.6
E(messages via unicast transmission instead of multicast.)54 648 Q
(By "echoing" this information to the recei)5 E -.15(ve)-.25 G 2.5(rs)
.15 G(et, suppression of)-2.5 E(Adamson, Borman, et al.)36 696 Q
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(feedback can be achie)54 84 Q -.15(ve)-.25 G 2.5
(de).15 G -.15(ve)-2.75 G 2.5(nw).15 G(hen recei)-2.5 E -.15(ve)-.25 G(\
rs are unicasting that feedback instead of multicasting it among the gr\
oup[11].).15 E/F1 10/Times-BoldItalic@0 SF(NORM_CMD\(REP)54 108 Q
(AIR_AD)-.85 E(V\) Message F)-.5 E(ormat)-.7 E/F2 10/Courier@0 SF 114
(0123)60 132 S 6(01234567890123456789012345678901)60 144 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
156 Q 24(|v)54 168 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
180 Q 162(|s)54 192 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
204 Q 36(|g)54 216 S 24(rtt | gsize |)-36 F(flavor = 4)12 E 30(|f)18 G
24(lags |)-30 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
228 Q 24(|c)54 240 S 12(c_flags |)-24 F 18(cc_rtt |)30 F 66(cc_rate |)72
F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
252 Q 138(|r)54 264 S(epair_adv_content ...)-138 E(|)108 E F0
(The "grtt", "gsize" and "\215a)54 288 Q -.2(vo)-.2 G(r" \214elds serv)
.2 E 2.5(et)-.15 G(he same purpose as in other)-2.5 E F2(NORM_CMD)2.5 E
F0(messages.)2.5 E(The "\215ags" \214eld pro)54 312 Q
(vide information on the)-.15 E F2(NORM_CMD)2.5 E F0(\(REP)A(AIR_AD)-.92
E(V\) content.)-.4 E(There is currently one)5 E F2(NORM_CMD)54 324 Q F0
(\(REP)A(AIR_AD)-.92 E(V\) \215ag de\214ned:)-.4 E F2
(NORM_REPAIR_ADV_FLAG_LIMIT = 0x01)205.2 348 Q F0(This \215ag is set by\
 the sender when it is unable to \214ts its full current repair state i\
nto a single NormSe)54 372 Q 2.5(gmentSize. If)-.15 F(this \215ag)2.5 E
(is set, recei)54 384 Q -.15(ve)-.25 G(rs should limit their N).15 E -.4
(AC)-.35 G(King to generating N).4 E -.4(AC)-.35 G
(Ks only up through the maximum ordinal transmission).4 E(position)54
396 Q/F3 10/Times-Italic@0 SF(\(objectId::fecBloc)2.5 E
(kId::fecSymbolId\))-.2 E F0(included in the "repair_adv_content".)2.5 E
(When congestion control operation is enabled, the "cc_\215ags", "cc_rt\
t", and "cc_rate" \214elds contain v)54 420 Q(alues for the recei)-.25 E
-.15(ve)-.25 G(r).15 E(with the lo)54 432 Q
(west calculated congestion control rate from which feedback w)-.25 E
(as recei)-.1 E -.15(ve)-.25 G 2.5(ds).15 G(ince the last)-2.5 E F2
(NORM_CMD)54 444 Q F0(\(REP)A(AIR_AD)-.92 E(V\) transmission.)-.4 E
(These \214elds are used by recei)5 E -.15(ve)-.25 G
(rs to suppress rounds of congestion control).15 E 2.5(feedback. The)54
456 R(de\214nition of these \214elds is gi)2.5 E -.15(ve)-.25 G 2.5(ni)
.15 G 2.5(nt)-2.5 G(he description of the)-2.5 E F2(NORM_CMD)2.5 E F0
(\(CC\) message belo)A -.65(w.)-.25 G(The "repair_adv_content" is in e)
54 480 Q(xactly the same form as the "nack_content" of)-.15 E F2
(NORM_NACK)2.5 E F0(messages and can be processed)2.5 E(by recei)54 492
Q -.15(ve)-.25 G
(rs for suppression purposes in the same manner with the e).15 E
(xception of the condition when the)-.15 E(NORM_REP)54 504 Q(AIR_AD)-.92
E(V_FLA)-.4 E(G_LIMIT is set.)-.4 E F1(NORM_CMD\(CC\) Message)54 528 Q
F0(The)54 552 Q F2(NORM_CMD)2.5 E F0
(\(CC\) messages contains \214elds to enable sender)A(->recei)-.2 E -.15
(ve)-.25 G 2.5(rg).15 G(roup greatest round-trip time \(GR)-2.5 E(TT\))
-.6 E(measurement and pro)54 564 Q
(vide congestion control information to the group.)-.15 E(The)5 E F2
(NORM_CMD)2.5 E F0(\(CC\) message is usually transmitted)A
(as part of NORM congestion control operation.)54 576 Q
(If NORM is operated in a pri)5 E -.25(va)-.25 G(te netw).25 E
(ork with congestion control operation)-.1 E(disabled, the)54 588 Q F2
(NORM_CMD)2.5 E F0(\(CC\) message is then used to f)A(acilitate GR)-.1 E
(TT measurement by the sender)-.6 E(.)-.55 E(Adamson, Borman, et al.)36
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-BoldItalic@0 SF
(NORM_CMD\(CC\) Message F)54 84 Q(ormat)-.7 E/F2 10/Courier@0 SF 114
(0123)60 108 S 6(01234567890123456789012345678901)60 120 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
132 Q 24(|v)54 144 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
156 Q 162(|s)54 168 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
180 Q 36(|g)54 192 S 24(rtt | gsize |)-36 F(flavor = 5)12 E 30(|f)18 G
24(lags |)-30 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
204 Q 150(|s)54 216 S 144(end_time_sec |)-150 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
228 Q 150(|s)54 240 S 138(end_time_usec |)-150 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
252 Q 66(|s)54 264 S 60(end_rate |)-66 F 6(cc_sequence |)12 F 12
(reserved |)24 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
276 Q 150(|c)54 288 S(c_node_list ...)-150 E(|)132 E F0
(The NORM common message header and standard)54 312 Q F2(NORM_CMD)2.5 E
F0(\214elds serv)2.5 E 2.5(et)-.15 G(heir usual purposes.)-2.5 E
(The "\215ags" \214eld is used to indicate)54 336 Q F2(NORM_CMD)2.5 E F0
(\(CC\) options.)A(Currently a single)5 E F2(NORM_CMD)2.5 E F0
(\(CC\) \215ag is de\214ned:)A F2(NORM_CC_FLAG_ENABLE = 0x01)226.2 360 Q
F0(When set, this indicates the sender has enabled congestion control f\
eedback collection, and recei)54 384 Q -.15(ve)-.25 G(rs should respond)
.15 E(observing the procedures describe in Section 5.5.2, "NORM Congest\
ion Control Operation".)54 396 Q(When this \215ag is cleared \(i.e.)5 E
(congestion control feedback collection is disabled\), this indicates t\
he sender is not observing congestion control operation)54 408 Q
(and the)54 420 Q F2(NORM_CMD)2.5 E F0
(\(CC\) message is being used only to pro)A
(vide a reference timestamp for GR)-.15 E(TT measurement via recei)-.6 E
-.15(ve)-.25 G(r).15 E F2(NORM_NACK)54 432 Q F0(feedback.)2.5 E
(The "send_time" \214eld is a timestamp indicating the time that the)54
456 Q F2(NORM_CMD)2.5 E F0(\(CC\) message w)A(as transmitted.)-.1 E
(This consists of)5 E 2.5(a6)54 468 S(4-bit \214eld containing 32-bits \
with the time in seconds \("sent_time_sec"\) and 32-bits with the time \
in microseconds)-2.5 E(\("send_time_usec"\) since some reference time t\
he source maintains \(usually 00:00:00, 1 January 1970\).)54 480 Q
(The byte ordering)5 E(of the \214elds is "Big Endian" netw)54 492 Q
(ork order)-.1 E 5(.R)-.55 G(ecei)-5 E -.15(ve)-.25 G
(rs use this timestamp adjusted by the amount of delay from when the).15
E(y)-.15 E(recei)54 504 Q -.15(ve)-.25 G 2.5(dt).15 G(he)-2.5 E F2
(NORM_CMD)2.5 E F0(\(CC\) message to when the)A 2.5(yr)-.15 G
(espond for the "grtt_response" portion of)-2.5 E F2(NORM_ACK)2.5 E F0
(and)2.5 E F2(NORM_NACK)54 516 Q F0(messages generated.)2.5 E(This allo)
5 E(ws the sender to e)-.25 E -.25(va)-.25 G
(luate the round-trip time to dif).25 E(ferent recei)-.25 E -.15(ve)-.25
G(rs for).15 E(congestion control and other \(e.g. GR)54 528 Q
(TT determination\) purposes.)-.6 E
(The "send_rate" \214eld indicates the sender')54 552 Q 2.5(sc)-.55 G
(urrent transmission rate in bytes per second.)-2.5 E
(The 16-bit "send_rate" \214eld)5 E(consists of 12 bits of mantissa in \
the most signi\214cant byte and 4 bits of base 10 e)54 564 Q
(xponent \(order of magnitude\) information)-.15 E
(in the least signi\214cant byte.)54 576 Q(The 12-bit mantissa portion \
of the \214eld is scaled such that a \215oating point v)5 E(alue of 0.0)
-.25 E(corresponds to 0 and a \215oating point v)54 588 Q
(alue of 10.0 corresponds to 4096.)-.25 E(Thus:)5 E F2
(value = \(int\) \(mantissa * 4096.0 / 10.0 + 0.5\))166.2 612 Q F0 -.15
(Fo)54 636 S 2.5(re).15 G(xample, to represent a transmission rate of 2\
56kbps \(3.2e+04 bytes per second\), the lo)-2.65 E
(wer 4 bits of the 16-bit \214eld)-.25 E(contain a v)54 648 Q
(alue of 0x04 to represent the e)-.25 E
(xponent while the upper 12 bits contain a v)-.15 E
(alue of 0x51f as determined from the)-.25 E(Adamson, Borman, et al.)36
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(equation gi)54 84 Q -.15(ve)-.25 G 2.5(na).15 G
(bo)-2.5 E -.15(ve)-.15 G(:).15 E/F1 10/Courier@0 SF
(value = \(int\)\(\(3.2 * 4096.0 / 10.0\) + 0.5\) = 1311 = 0x51f)133.2
108 Q F0 1.6 -.8(To d)54 132 T(ecode the "send_rate" \214eld, the follo)
.8 E(wing equation can be used:)-.25 E F1
(sendRate = <upper12bits> * 10.0 / 4096.0 * power\(10.0, <lower4bits>\))
100.2 156 Q F0(Note the maximum transmission rate representable by this\
 scheme is approximately 9.99e+15 bytes per second.)54 180 Q(The "cc_se\
quence" \214eld is a sequence number applied by the sender to congestio\
n control command messages.)54 204 Q(The greatest)5 E(recei)54 216 Q
-.15(ve)-.25 G 2.5(d").15 G(cc_sequence" v)-2.5 E
(alue is recorded by recei)-.25 E -.15(ve)-.25 G
(rs and fed back to the sender in an).15 E(y)-.15 E F1(NORM_ACK)2.5 E F0
(or)2.5 E F1(NORM_NACK)2.5 E F0(messages generated by the recei)54 228 Q
-.15(ve)-.25 G(rs for that sender).15 E(.)-.55 E(The "reserv)54 252 Q(e\
d" \214eld is for potential future use and should be set to zero in thi\
s v)-.15 E(ersion of the NORM protocol.)-.15 E(The "cc_node_list" consi\
sts of a list of NormNodeIds and their associated congestion control st\
atus.)54 276 Q(This includes the)5 E(current limiting recei)54 288 Q
-.15(ve)-.25 G 2.5(r\().15 G(CLR\) node, an)-2.5 E 2.5(yp)-.15 G
(otential limiting recei)-2.5 E -.15(ve)-.25 G 2.5(r\().15 G
(PLR\) nodes which ha)-2.5 E .3 -.15(ve b)-.2 H
(een identi\214ed, and some).15 E(number of recei)54 300 Q -.15(ve)-.25
G(rs for which congestion control status is being pro).15 E
(vided, most notably including the recei)-.15 E -.15(ve)-.25 G
(rs' current R).15 E(TT)-.6 E 2.5(measurement. The)54 312 R
(length of the "cc_node_list" pro)2.5 E
(vides for at least the CLR and one other recei)-.15 E -.15(ve)-.25 G .8
-.4(r, b).15 H(ut may be).2 E
(con\214gurable for more timely feedback to the group.)54 324 Q
(The list length can be inferred from the length of the)5 E F1(NORM_CMD)
2.5 E F0(\(CC\))A(message.)54 336 Q
(Each item in the "cc_node_list" is in the follo)54 360 Q(wing format:)
-.25 E/F2 10/Times-BoldItalic@0 SF(Congestion Control Node List Item F)
54 384 Q(ields)-.4 E F1 114(0123)60 408 S 6
(01234567890123456789012345678901)60 420 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
432 Q 156(|c)54 444 S 156(c_node_id |)-156 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
456 Q 24(|c)54 468 S 12(c_flags |)-24 F 18(cc_rtt |)30 F 66(cc_rate |)72
F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
480 Q F0(The "cc_node_id" is the NormNodeId of the recei)54 504 Q -.15
(ve)-.25 G 2.5(rw).15 G(hich the item represents.)-2.5 E(The "cc_\215ag\
s" \214eld contains \215ags indicating the congestion control status of\
 the indicated recei)54 528 Q -.15(ve)-.25 G 3.6 -.55(r. T).15 H
(he follo).55 E(wing \215ags are)-.25 E(de\214ned:)54 540 Q
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E .4 LW 537.32 76.5 71.08 76.5 DL 61.345(Flag V)
124.925 86 R 140.39(alue Purpose)-1.11 F 537.32 90.5 71.08 90.5 DL
(NORM_CC_FLA)76.08 100 Q 25.855(G_CLR 0x01)-.4 F(Recei)244.32 100 Q -.15
(ve)-.25 G 2.5(ri).15 G 2.5(st)-2.5 G(he current limiting recei)-2.5 E
-.15(ve)-.25 G 2.5(r\().15 G(CLR\))-2.5 E 537.32 104.5 71.08 104.5 DL
(NORM_CC_FLA)76.08 114 Q 26.965(G_PLR 0x02)-.4 F(Recei)244.32 114 Q -.15
(ve)-.25 G 2.5(ri).15 G 2.5(sap)-2.5 G(otential limiting recei)-2.5 E
-.15(ve)-.25 G 2.5(r\().15 G(PLR\))-2.5 E 537.32 118.5 71.08 118.5 DL
(NORM_CC_FLA)76.08 128 Q(G_R)-.4 E 27.015(TT 0x04)-.6 F(Recei)244.32 128
Q -.15(ve)-.25 G 2.5(rh).15 G(as measured R)-2.5 E
(TT with respect to sender)-.6 E 537.32 132.5 71.08 132.5 DL
(NORM_CC_FLA)76.08 142 Q(G_ST)-.4 E(AR)-.93 E 17.665(T0)-.6 G(x08)
-17.665 E(Sender/recei)244.32 142 Q -.15(ve)-.25 G 2.5(ri).15 G 2.5(si)
-2.5 G 2.5(n")-2.5 G(slo)-2.5 E 2.5(ws)-.25 G
(tart" phase of congestion control operation)-2.5 E(\(i.e. The recei)
244.32 154 Q -.15(ve)-.25 G 2.5(rh).15 G(as not yet detected an)-2.5 E
2.5(yp)-.15 G(ack)-2.5 E(et loss and the "cc_rate")-.1 E
(\214eld is a function of the recei)244.32 166 Q -.15(ve)-.25 G(r').15 E
2.5(sm)-.55 G(easured recei)-2.5 E .3 -.15(ve r)-.25 H(ate\).).15 E
537.32 170.5 71.08 170.5 DL(NORM_CC_FLA)76.08 180 Q(G_LEA)-.4 E 13.885
(VE 0x10)-1.35 F(Recei)244.32 180 Q -.15(ve)-.25 G 2.5(ri).15 G 2.5(si)
-2.5 G(mminently lea)-2.5 E
(ving the session and its feedback should not)-.2 E
(be considered in congestion control operation.)244.32 192 Q 537.32
196.5 71.08 196.5 DL 537.32 76.5 537.32 196.5 DL 71.08 76.5 71.08 196.5
DL 236.82 76.5 236.82 196.5 DL 199.05 76.5 199.05 196.5 DL
(The "cc_rtt" contains a quantized representation of the recei)54 222 Q
-.15(ve)-.25 G(r').15 E 2.5(si)-.55 G(ndi)-2.5 E(vidual sender<->recei)
-.25 E -.15(ve)-.25 G 2.5(rR).15 G(TT as measured by the)-3.1 E(sender)
54 234 Q 5(.T)-.55 G(his \214eld is v)-5 E(alid only if the)-.25 E/F1 10
/Courier@0 SF(NORM_FLAG_RTT)2.5 E F0
(\215ag is set in the "cc_\215ags" \214eld.)2.5 E
(This one byte \214eld is a quantized)5 E(representation of the R)54 246
Q(TT using the algorithm described in the NORM Building Block document \
[15].)-.6 E
(The "cc_rate" \214eld contains a representation of the recei)54 270 Q
-.15(ve)-.25 G(r').15 E 2.5(sc)-.55 G
(urrent calculated \(during steady-state congestion control)-2.5 E
(operation\) or twice its measured \(during the "slo)54 282 Q 2.5(ws)
-.25 G(tart" phase\) congestion control rate.)-2.5 E
(This \214eld is encoded and decoded)5 E
(using the same technique as described for the)54 294 Q F1(NORM_CMD)2.5
E F0(\(CC\) "send_rate" \214eld.)A/F2 10/Times-BoldItalic@0 SF
(NORM_CMD\(A)54 318 Q(CK_REQ\) Message)-.65 E F0(The)54 342 Q F1
(NORM_CMD)2.5 E F0(\(A)A
(CK_REQ\) message is used by the sender to request ackno)-.4 E
(wledgement from a speci\214ed list of recei)-.25 E -.15(ve)-.25 G(rs.)
.15 E(This message is used in pro)54 354 Q(viding a lightweight positi)
-.15 E .3 -.15(ve a)-.25 H(ckno).15 E
(wledgement mechanism that is OPTION)-.25 E(AL for use by the)-.35 E
(reliable multicast application.)54 366 Q
(The NORM protocol de\214nes a speci\214c ackno)5 E
(wledgement mechanism to determine that)-.25 E -.1(wa)54 378 S
(termark points in the reliable transmission ha).1 E .3 -.15(ve b)-.2 H
(een achie).15 E -.15(ve)-.25 G 2.5(db).15 G 2.5(ys)-2.5 G
(peci\214c recei)-2.5 E -.15(ve)-.25 G 2.5(rs. Addtionally).15 F 2.5
(,ar)-.65 G(ange of)-2.5 E(ackno)54 390 Q
(wledgement request types is pro)-.25 E
(vided for use at the application')-.15 E 2.5(sd)-.55 G 2.5
(iscretion. Pro)-2.5 F(vision for application-de\214ned,)-.15 E(positi)
54 402 Q -.15(ve)-.25 G(ly-ackno).15 E(wledged commands allo)-.25 E
(ws the application to automatically tak)-.25 E 2.5(ea)-.1 G(dv)-2.5 E
(antage of transmission and round-trip)-.25 E(timing information a)54
414 Q -.25(va)-.2 G(ilable to the NORM protocol.).25 E
(The details of the NORM positi)5 E .3 -.15(ve a)-.25 H(ckno).15 E
(wledgement process including)-.25 E(transmission of the)54 426 Q F1
(NORM_CMD)2.5 E F0(\(A)A(CK_REQ\) messages and the recei)-.4 E -.15(ve)
-.25 G 2.5(rr).15 G(esponse \()-2.5 E F1(NORM_ACK)A F0 2.5(\)a)C
(re described in Section)-2.5 E 2.5(5.5.3. The)54 438 R(format of the)
2.5 E F1(NORM_CMD)2.5 E F0(\(A)A(CK_REQ\) message is:)-.4 E F2
(NORM_CMD\(A)54 462 Q(CK_REQ\) Message F)-.65 E(ormat)-.7 E F1 114(0123)
60 486 S 6(01234567890123456789012345678901)60 498 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
510 Q 24(|v)54 522 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
534 Q 162(|s)54 546 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
558 Q 36(|g)54 570 S 24(rtt | gsize |)-36 F(flavor = 3)12 E 24(|a)18 G
12(ck_type |)-24 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
582 Q 144(|a)54 594 S 138(ck_req_content |)-144 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
606 Q 132(|a)54 618 S(ck_req_content \(cont'd\))-132 E(|)102 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
630 Q 138(|a)54 642 S(cking_node_list ...)-138 E(|)120 E F0
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 21])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(The NORM common message header and standard)54 84
Q/F1 10/Courier@0 SF(NORM_CMD)2.5 E F0(\214elds serv)2.5 E 2.5(et)-.15 G
(heir usual purposes.)-2.5 E
(The "ack_type" \214eld indicates type of ackno)54 108 Q
(wledemgent being requested and thus implies rules for ho)-.25 E 2.5(wt)
-.25 G(he recei)-2.5 E -.15(ve)-.25 G 2.5(rw).15 G(ill)-2.5 E
(treat this request.)54 120 Q(The follo)5 E(wing "ack_type" v)-.25 E
(alues are de\214ned and are also used in)-.25 E F1(NORM_ACK)2.5 E F0
(messages described later:)2.5 E .4 LW 514.915 142.5 93.485 142.5 DL -.4
(AC)136.555 152 S 2.5(KT).4 G 53.35(ype V)-3.3 F 112.42(alue Purpose)
-1.11 F 514.915 156.5 93.485 156.5 DL F1(NORM_ACK)98.485 166 Q F0(\(W)A
-1.11(AT)-1.2 G 37.03(ERMARK\) 1)1.11 F(Used to request ackno)275.915
166 Q(wledgement of reliable reception of)-.25 E -.1(wa)275.915 178 S
(termark transmission point.).1 E 514.915 182.5 93.485 182.5 DL F1
(NORM_ACK)98.485 192 Q F0 86.93(\(CC\) 2)B(Used to identify)275.915 192
Q F1(NORM_ACK)2.5 E F0(messages sent for congestion)2.5 E(control only)
275.915 204 Q(.)-.65 E 514.915 208.5 93.485 208.5 DL F1(NORM_ACK)98.485
218 Q F0(\(RESER)A 36.07(VED\) 3-15)-.8 F(Reserv)275.915 218 Q
(ed for possible future NORM protocol use.)-.15 E 514.915 222.5 93.485
222.5 DL F1(NORM_ACK)98.485 232 Q F0(\(APPLICA)A 12.5(TION\) 16-255)
-1.11 F(Used at application')275.915 232 Q 2.5(sd)-.55 G(iscretion.)-2.5
E 514.915 236.5 93.485 236.5 DL 514.915 142.5 514.915 236.5 DL 93.485
142.5 93.485 236.5 DL 268.415 142.5 268.415 236.5 DL 225.085 142.5
225.085 236.5 DL(The "ack_req_content" \214eld consists of 8 bytes whic\
h is interpreted dif)54 262 Q(ferently for dif)-.25 E
(ferent "ack_type" v)-.25 E(alues.)-.25 E
(The "acking_node_list" \214eld is a list of NormNodeIds.)54 286 Q
(The listed NormNodes are e)5 E(xpected to e)-.15 E
(xplicitly respond to the)-.15 E(ackno)54 298 Q
(wledgement request according the rules for the type of ackno)-.25 E
(wledgment requested and the NORM Positi)-.25 E -.15(ve)-.25 G(Ackno)54
310 Q(wledgment procedure described in Section 5.3.3.)-.25 E(The)54 334
Q F1(NORM_ACK)2.5 E F0(\(W)A -1.11(AT)-1.2 G
(ERMARK\) type indicates the sender wishes to recei)1.11 E .3 -.15(ve a)
-.25 H(ckno).15 E(wledgement from recei)-.25 E -.15(ve)-.25 G(rs in the)
.15 E("acking_node_list" who ha)54 346 Q .3 -.15(ve a)-.2 H(chie).15 E
-.15(ve)-.25 G 2.5(dc).15 G
(ompletion of reception through a speci\214c "w)-2.5 E
(atermark point" in terms of a logical)-.1 E(transmission position.)54
358 Q(This "w)5 E(atermark point" is gi)-.1 E -.15(ve)-.25 G 2.5(ni).15
G 2.5(nt)-2.5 G(he "ack_req_content" \214eld.)-2.5 E(The format of the)
54 382 Q F1(NORM_CMD)2.5 E F0(\(A)A(CK_REQ\(W)-.4 E -1.11(AT)-1.2 G
(ERMARK\)\) message is:)1.11 E/F2 10/Times-BoldItalic@0 SF(NORM_CMD\(A)
54 406 Q(CK_REQ\(W)-.65 E -.55(AT)-.74 G(ERMARK\)\) Message F).55 E
(ormat)-.7 E F1 114(0123)60 430 S 6(01234567890123456789012345678901)60
442 S(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
54 454 Q 24(|v)54 466 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
478 Q 162(|s)54 490 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
502 Q 36(|g)54 514 S 24(rtt | gsize |)-36 F(flavor = 3)12 E 6(|a)18 G
(ck_flavor = 1|)-6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
526 Q 36(|o)54 538 S 30(bject_transport_id |)-36 F
(fec_block_number \(msb\))24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
550 Q 30(|f)54 562 S(ec_block_number \(lsb\))-30 E 48(|f)24 G 54
(ec_symbol_id |)-48 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
574 Q 132(|a)54 586 S(cking_node_list ...)-132 E(|)126 E F0
(The NORM common message header and standard)54 610 Q F1(NORM_CMD)2.5 E
F0(\214elds serv)2.5 E 2.5(et)-.15 G(heir usual purposes.)-2.5 E
(The "ack_\215a)5 E -.2(vo)-.2 G(r" is set to).2 E 2.5(av)54 622 S
(alue of one.)-2.75 E(The "object_transport_id", "fec_block_number", an\
d "fec_symbol_id" are used to identify the w)54 646 Q
(atermark point for which)-.1 E(positi)54 658 Q .3 -.15(ve a)-.25 H
(ckno).15 E(wledgement is requested.)-.25 E(This w)5 E
(atermark point is similar to the transmission position gi)-.1 E -.15
(ve)-.25 G 2.5(ni).15 G(n)-2.5 E(Adamson, Borman, et al.)36 696 Q
(Expires September 2003)110.05 E([P)118.25 E(age 22])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Courier@0 SF(NORM_CMD)54 84 Q F0
(\(FLUSH\) messages.)A(Furthermore, NORM recei)5 E -.15(ve)-.25 G
(rs \(whether or not the).15 E 2.5(ya)-.15 G
(re included in the "acking_node_list"\))-2.5 E(SHALL treat the A)54 96
Q(CK_REQ\(W)-.4 E -1.11(AT)-1.2 G(ERMARK\) command as equi)1.11 E -.25
(va)-.25 G(lent to a).25 E F1(NORM_CMD)2.5 E F0(\(FLUSH\) command and)A
(appropriately initiate N)54 108 Q -.4(AC)-.35 G 2.5(Kr).4 G(epair c)
-2.5 E(ycles in response to an)-.15 E 2.5(yd)-.15 G
(etected missing data up through the indicated w)-2.5 E(atermark)-.1 E
(point.)54 120 Q(The "acking_node_list" \214eld contains the NormNodeId\
s of the current NORM recei)54 144 Q -.15(ve)-.25 G
(rs which should positi).15 E .3 -.15(ve a)-.25 H(ckno).15 E(wledge)-.25
E(\()54 156 Q F1(NORM_ACK)A F0 2.5(\)t)C(his request.)-2.5 E(The pack)5
E(et payload length implies the length of the "acking_node_list" and it\
s length is limited)-.1 E(to the NormSe)54 168 Q 2.5(gmentSize. The)-.15
F(indi)2.5 E(vidual NormNodeId items are listed in netw)-.25 E
(ork \(Big Endian\) order)-.1 E 5(.I)-.55 G 2.5(far)-5 G(ecei)-2.5 E
-.15(ve)-.25 G 2.5(ri).15 G(s)-2.5 E(included in the "acking_node_list"\
 and it has no repair needs up through the w)54 180 Q
(atermark point, it SHALL schedule)-.1 E(transmission of a)54 192 Q F1
(NORM_ACK)2.5 E F0(message as described in Section 5.5.3.)2.5 E(The)54
216 Q F1(NORM_ACK)2.5 E F0(\(CC\) type is pro)A
(vided only for when recei)-.15 E -.15(ve)-.25 G(rs generate).15 E F1
(NORM_ACK)2.5 E F0(messages in response to)2.5 E F1(NORM_CMD)54 228 Q F0
(\(CC\) messages for congestion control operation.)A
(There is no corresponding)5 E F1(NORM_CMD)2.5 E F0(\(A)A
(CK_REQ\(CC\)\))-.4 E(message.)54 240 Q(The)54 264 Q F1(NORM_ACK)2.5 E
F0(\(RESER)A(VED\) range of types is pro)-.8 E
(vided for possible future NORM protocol use.)-.15 E(The)54 288 Q F1
(NORM_ACK)2.5 E F0(\(APPLICA)A(TION\) range of types is pro)-1.11 E
(vided so that NORM applications may implement application-)-.15 E
(de\214ned, positi)54 300 Q -.15(ve)-.25 G(ly-ackno).15 E
(wledged commands which are able to le)-.25 E -.15(ve)-.25 G
(rage internal transmission and round-trip timing).15 E(information a)54
312 Q -.25(va)-.2 G(ilable to the NORM protocol implementation.).25 E
(The interpretation of the "ack_req_content" is application-)5 E
(de\214ned in this case.)54 324 Q/F2 10/Times-BoldItalic@0 SF
(NORM_CMD\(APPLICA)54 348 Q(TION\) Message)-.55 E F0(This command allo)
54 372 Q(ws the NORM application to rob)-.25 E
(ustly transmit application-de\214ned commands.)-.2 E
(The command message)5 E(preempts an)54 384 Q 2.5(yo)-.15 G
(ngoing data transmission and is repeated)-2.5 E F1(NORM_ROBUST_FACTOR)
2.5 E F0(times at a rate of once per 2*GR)2.5 E(TT)-.6 E(.)-.74 E
(This rate of repetition allo)54 396 Q(ws the application to collect an)
-.25 E 2.5(yr)-.15 G(esponse \(if that is the application')-2.5 E 2.5
(sp)-.55 G(urpose for the command\))-2.5 E(before it is repeated.)54 408
Q(Possible responses might include initiation of data transmission ,)5 E
F1(NORM_CMD)2.5 E F0(\(APPLICA)A(TION\))-1.11 E(messages, or e)54 420 Q
-.15(ve)-.25 G 2.5(na).15 G(pplication-de\214ned, positi)-2.5 E -.15(ve)
-.25 G(ly-ackno).15 E
(wledge commands from other NormSession participants.)-.25 E(The)5 E
(transmission of these commands will preempt data transmission when the)
54 432 Q 2.5(ya)-.15 G(re scheduled and may be multiple)-2.5 E -.15(xe)
-.15 G 2.5(dw).15 G(ith)-2.5 E(ongoing data transmission.)54 444 Q
(This type of rob)5 E(ustly transmitted command allo)-.2 E
(ws NORM applications to de\214ne a complete set)-.25 E(of session cont\
rol mechanisms with less state than the transfer of FEC encoded reliabl\
e content requires while taking)54 456 Q(adv)54 468 Q
(antage of NORM transmission and round-trip timing information.)-.25 E
F2(NORM_CMD\(APPLICA)54 492 Q(TION\) Message F)-.55 E(ormat)-.7 E F1 114
(0123)60 504 S 6(01234567890123456789012345678901)60 516 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
528 Q 24(|v)54 540 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
552 Q 162(|s)54 564 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
576 Q 36(|g)54 588 S 24(rtt | gsize |)-36 F(flavor = 6)12 E 18(|r)18 G
18(eserved |)-18 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
600 Q 114(|a)54 612 S(pplication defined content ...)-114 E(|)78 E F0
(The NORM common message header and)54 648 Q F1(NORM_CMD)2.5 E F0
(\214elds are interpreted as pre)2.5 E(viously described.)-.25 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 23])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(The "application-de\214ned content" contains info\
rmation in a format at the discretion of the application.)54 84 Q
(The size of this)5 E(payload is limited a maximum of the sender')54 96
Q 2.5(sN)-.55 G(ormSe)-2.5 E(gmentSize setting.)-.15 E/F1 10
/Times-Bold@0 SF(4.3 Recei)36 120 Q -.1(ve)-.1 G 2.5(rM).1 G(essages)
-2.5 E F0(The NORM message types generated by pariticipating recei)54
144 Q -.15(ve)-.25 G(rs consist of).15 E/F2 10/Courier@0 SF(NORM_NACK)
2.5 E F0(and)2.5 E F2(NORM_ACK)2.5 E F0(message types.)2.5 E F2
(NORM_NACK)54 156 Q F0(messages are sent to request repair of missing d\
ata content from sender transmission and)2.5 E F2(NORM_ACK)2.5 E F0(mes\
sages are generated in response to certain sender commands including)54
168 Q F2(NORM_CMD)2.5 E F0(\(CC\) and NORM_CMD\(A)A(CK_REQ\).)-.4 E/F3
10/Times-BoldItalic@0 SF(4.3.1 NORM_N)54 192 Q -.65(AC)-.3 G 2.5(KM).65
G(essage)-2.5 E F0(The principal purpose of)54 216 Q F2(NORM_NACK)2.5 E
F0(messages is for recei)2.5 E -.15(ve)-.25 G
(rs to request repair of sender content via selecti).15 E -.15(ve)-.25 G
2.5(,n).15 G -2.25 -.15(eg a)-2.5 H(ti).15 E -.15(ve)-.25 G(ackno)54 228
Q(wledgement upon detection of incomplete data.)-.25 E F2(NORM_NACK)5 E
F0(messages will be transmitted according to the rules of)2.5 E F2
(NORM_NACK)54 240 Q F0
(generation and suppression described in Section 5.3.)2.5 E
(The content of these messages is in a format that can)5 E
(potentially be used by compatible intermediate systems [12] to pro)54
252 Q(vide assistance in promoting protocol scalability and)-.15 E(ef)54
264 Q(\214cienc)-.25 E 2.5(yw)-.15 G(hen a)-2.5 E -.25(va)-.2 G(ilable.)
.25 E F2(NORM_NACK)5 E F0
(messages also contain additional \214elds to pro)2.5 E
(vide feedback to the sender\(s\) for)-.15 E
(purposes of round-trip timing collection and congestion control.)54 276
Q(The payload of)54 300 Q F2(NORM_NACK)2.5 E F0
(messages contains one or more repair requests for dif)2.5 E
(ferent objects or portions of those)-.25 E 2.5(objects. The)54 312 R F2
(NORM_NACK)2.5 E F0(message format is as follo)2.5 E(ws:)-.25 E F3
(NORM_N)54 336 Q -.65(AC)-.3 G 2.5(KM).65 G(essage F)-2.5 E(ormat)-.7 E
F2 114(0123)60 360 S 6(01234567890123456789012345678901)60 372 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
384 Q 24(|v)54 396 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
408 Q 162(|s)54 420 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
432 Q 162(|s)54 444 S 156(erver_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
456 Q 138(|g)54 468 S 132(rtt_response_sec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
480 Q 138(|g)54 492 S 126(rtt_response_usec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
504 Q 24(|c)54 516 S 12(c_flags |)-24 F 18(cc_rtt |)30 F 66(cc_loss |)72
F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
528 Q 72(|c)54 540 S 66(c_rate |)-72 F 6(cc_sequence |)12 F 12
(reserved |)24 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
552 Q 156(|n)54 564 S(ack_content ...)-156 E(|)126 E F0
(The NORM common message header \214elds serv)54 588 Q 2.5(et)-.15 G
(heir usual purposes.)-2.5 E(The "serv)54 612 Q
(er_id" \214eld identi\214es the NORM sender to which the)-.15 E F2
(NORM_NACK)2.5 E F0(message is destined.)2.5 E
(The "grtt_response" \214elds contain an adjusted v)54 636 Q
(ersion of the timestamp from the most recently recei)-.15 E -.15(ve)
-.25 G(d).15 E F2(NORM_CMD\(CC\))2.5 E F0
(message for the indicated NORM sender)54 648 Q 5(.T)-.55 G
(he format of the "grtt_response" is the same as the)-5 E
("send_time" \214eld of the)5 E(Adamson, Borman, et al.)36 696 Q
(Expires September 2003)110.05 E([P)118.25 E(age 24])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Courier@0 SF(NORM_CMD)54 84 Q F0 2.5
(\(CC\). The "grtt_response")B -.25(va)2.5 G(lue is _relati).25 E -.15
(ve)-.25 G 2.5(_t).15 G 2.5(ot)-2.5 G(he "send_time" the source pro)-2.5
E(vided with a corresponding)-.15 E F1(NORM_CMD)54 96 Q F0
(\(CC\) command.)A(The recei)5 E -.15(ve)-.25 G 2.5(ra).15 G
(djusts the source')-2.5 E(s)-.55 E F1(NORM_CMD)2.5 E F0
(\(CC\) "send_time" timestamp by adding the time)A(dif)54 108 Q
(ferential from)-.25 E(when the recei)5 E -.15(ve)-.25 G 2.5(rr).15 G
(ecei)-2.5 E -.15(ve)-.25 G 2.5(dt).15 G(he)-2.5 E F1(NORM_CMD)2.5 E F0
(\(CC\) to when the)A F1(NORM_NACK)2.5 E F0
(is transmitted to calculate the)2.5 E -.25(va)54 120 S
(lue in the "grtt_response" \214eld.).25 E(This is the "recei)5 E -.15
(ve)-.25 G(_to_response_dif).15 E(ferential" v)-.25 E
(alue used in the follo)-.25 E(wing formula:)-.25 E F1("grtt_response" \
= NORM_CMD\(CC\) "send_time" + receive_to_response_differential)73.2 144
Q F0(The recei)54 168 Q -.15(ve)-.25 G 2.5(rS).15 G
(HALL set the "grtt_response" to a ZER)-2.5 E 2.5(Ov)-.4 G
(alue, to indicate that the it has not yet recei)-2.75 E -.15(ve)-.25 G
2.5(da).15 G F1(NORM_CMD)A F0(\(CC\))A(message from the indicated sende\
r and that the sender should ignore the "grtt_response" in this message\
.)54 180 Q
(The "cc_\215ags" \214eld contains bits representing the recei)54 204 Q
-.15(ve)-.25 G(r').15 E 2.5(ss)-.55 G
(tate with respect to congestion control operation.)-2.5 E(The possible)
5 E -.25(va)54 216 S
(lues for the "cc_\215ags" \214eld are those speci\214ed for the).25 E
F1(NORM_CMD)2.5 E F0(\(CC\) message node list item \215ags.)A
(The "cc_rtt" \214eld SHALL be set to a def)54 240 Q(ault maximum v)-.1
E(alue and the)-.25 E F1(NORM_CC_FLAG_RTT)2.5 E F0
(\215ag SHALL be cleared when)2.5 E(the recei)54 252 Q -.15(ve)-.25 G
2.5(rh).15 G(as not yet recei)-2.5 E -.15(ve)-.25 G 2.5(dR).15 G
(TT measurement information.)-3.1 E(When the recei)5 E -.15(ve)-.25 G
2.5(rh).15 G(as recei)-2.5 E -.15(ve)-.25 G 2.5(dR).15 G(TT measurement)
-3.1 E(information, it shall set the "cc_rtt" v)54 264 Q
(alue accordingly and set the)-.25 E F1(NORM_CC_FLAG_RTT)2.5 E F0
(\215ag in the "cc_\215ags" \214eld.)2.5 E
(The "cc_loss" \214eld is the recei)54 288 Q -.15(ve)-.25 G(r').15 E 2.5
(sc)-.55 G(urrent pack)-2.5 E
(et loss fraction estimate for the indicated source.)-.1 E
(The loss fraction is a v)5 E(alue)-.25 E
(from 0.0 to 1.0 corresponding to a range of zero to 100 percent pack)54
300 Q(et loss. The 16-bit "cc_loss" v)-.1 E(alue is calculated by the)
-.25 E(follo)54 312 Q(wing formula:)-.25 E F1
("cc_loss" = decimal_loss_fraction * 65535.0)175.2 336 Q F0
(The "cc_rate" \214eld represents the recei)54 360 Q -.15(ve)-.25 G
(rs current local congestion control rate.).15 E(During "slo)5 E 2.5(ws)
-.25 G(tart", when the recei)-2.5 E -.15(ve)-.25 G 2.5(rh).15 G(as)-2.5
E(detected no loss, this v)54 372 Q(alue is set to twice the actual rat\
e it has measured from the corresponding sender and the)-.25 E
(NORM_CC_FLA)54 384 Q(G_ST)-.4 E(AR)-.93 E 2.5(Ti)-.6 G 2.5(ss)-2.5 G
(et in the "cc_\215ags' \214eld.)-2.5 E(Otherwise, the recei)5 E -.15
(ve)-.25 G 2.5(rc).15 G(alculates a congestion control rate based)-2.5 E
(on its loss measurement and R)54 396 Q(TT measurement information \(e)
-.6 E -.15(ve)-.25 G 2.5(ni).15 G 2.5(fd)-2.5 G(ef)-2.5 E
(ault\) for the "cc_rate" \214eld.)-.1 E(The "cc_sequence" \214eld cont\
ains the current greatest "cc_sequence" number of recei)54 420 Q -.15
(ve)-.25 G(d).15 E F1(NORM_CMD)2.5 E F0(\(CC\) messages from)A
(the corresponding sender)54 432 Q 5(.T)-.55 G(his information can assi\
st the sender in congestion control operation by pro)-5 E
(viding an indicator)-.15 E(of ho)54 444 Q 2.5(wc)-.25 G
(urrent \("fresh"\) the recei)-2.5 E -.15(ve)-.25 G(r').15 E 2.5(sr)-.55
G(ound-trip measurement reference time is and whether the recei)-2.5 E
-.15(ve)-.25 G 2.5(rh).15 G(as been)-2.5 E(successfully recei)54 456 Q
(ving recent congestion control probes.)-.25 E -.15(Fo)5 G 2.5(re).15 G
(xample, if it is apparent the recei)-2.65 E -.15(ve)-.25 G 2.5(rh).15 G
(as not been recei)-2.5 E(ving)-.25 E(recent congestion control probes \
\(and thus possibly other messages from the sender\), the sender may ch\
oose to tak)54 468 Q(e)-.1 E(congestion a)54 480 Q -.2(vo)-.2 G
(idance measures.).2 E(The "reserv)54 504 Q
(ed" \214eld is for potential future NORM)-.15 E
(use and SHALL be set to ZER)5 E 2.5(Of)-.4 G(or this v)-2.5 E
(ersion of the protocol.)-.15 E(The "nack_content" of the)54 528 Q F1
(NORM_NACK)2.5 E F0(message speci\214es the repair needs of the recei)
2.5 E -.15(ve)-.25 G 2.5(rw).15 G(ith respect to the NORM sender)-2.5 E
(indicated by the "serv)54 540 Q(er_id" \214eld.)-.15 E(The recei)5 E
-.15(ve)-.25 G 2.5(rc).15 G(onstructs repair requests based on the)-2.5
E F1(NORM_DATA)2.5 E F0(and/or)2.5 E F1(NORM_INFO)2.5 E F0(se)54 552 Q(\
gments it requires from the sender in order to complete reliable recept\
ion.)-.15 E 2.5(As)5 G(ingle repair request consists of a list of)-2.5 E
(items, ranges, and/or FEC coding block erasure counts for needed)54 564
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(repair requests may be concatenated within the\
 "nack_content" \214eld of a)54 576 Q F1(NORM_NACK)2.5 E F0 2.5
(message. Note)2.5 F(that a single repair)2.5 E(request can possibly in\
clude multiple "items", "ranges", or "erasure_counts".)54 588 Q
(In turn, the "nack_content" \214eld may contain)5 E
(multiple repair request.)54 600 Q 2.5(As)5 G
(ingle repair request has the follo)-2.5 E(wing format:)-.25 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 25])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-BoldItalic@0 SF -.3(NA)54 84 S
(CK Repair Request F)-.35 E(ormat)-.7 E/F2 10/Courier@0 SF 114(0123)60
108 S 6(01234567890123456789012345678901)60 120 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
132 Q 24(|f)54 144 S 36(orm |)-24 F 30(flags |)24 F 78(length |)66 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
156 Q 30(|o)54 168 S 36(bject_transport_id |)-30 F
(fec_block_number \(msb\))30 E(|)24 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
180 Q 30(|f)54 192 S(ec_block_number \(lsb\))-30 E 6(|f)24 G
(ec_symbol_id or erasure_count|)-6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
204 Q 180(|.)54 216 S 174(.. |)-180 F F0(The "form" \214eld indicates c\
urrently whether the repair request content that follo)54 240 Q
(ws is a list of)-.25 E F2(NORM_NACK_ITEMS)2.5 E F0(,)A F2
(NORM_NACK_RANGES)54 252 Q F0 2.5(,o)C(r)-2.5 E F2(NORM_NACK_ERASURES)
2.5 E F0 5(.P)C(ossible v)-5 E(alues for the "form" \214eld include:)
-.25 E -.15(Fo)274.555 294 S 55.74(rm V).15 F(alue)-1.11 E F2
(NORM_NACK_ITEMS)231.315 306 Q F0(1)41.885 E F2(NORM_NACK_RANGES)231.315
318 Q F0(2)35.885 E F2(NORM_NACK_ERASURES)231.315 330 Q F0(3)23.885 E
(When the repair request consists of indi)54 360 Q(vidual)-.25 E F2
(NORM_NACK_ITEMS)2.5 E F0 2.5(,e)C(ach concatenation of)-2.5 E/F3 10
/Times-Italic@0 SF(object_tr)54 372 Q(ansport_id::fec_bloc)-.15 E
(k_number::fec_symbol_id)-.2 E F0(identi\214es an indi)2.5 E
(vidual repair need. When the repair request "form")-.25 E(is)54 384 Q
F2(NORM_NACK_RANGES)5 E F0 2.5(,t)C(he inclusi)-2.5 E .3 -.15(ve r)-.25
H(ange of sender information needed by the recei).15 E .3 -.15(ve i)-.25
H 2.5(sg).15 G -2.15 -.25(iv e)-2.5 H 2.5(ni).25 G 2.5(np)-2.5 G
(airs of)-2.5 E F3(object_tr)54 396 Q(ansport_id::fec_bloc)-.15 E
(k_number::fec_symbol_id)-.2 E F0 5(.W)C(hen the repair request form is)
-5 E F2(NORM_NACK_ERASURES)2.5 E F0 2.5(,e)C(ach)-2.5 E F3(object_tr)54
408 Q(ansport_id::fec_bloc)-.15 E(k_number::er)-.2 E(asur)-.15 E
(e_count)-.37 E F0(concatenation listed)2.5 E(indicates the recei)5 E
-.15(ve)-.25 G(r').15 E 2.5(sF)-.55 G(EC erasure count for)-2.5 E
(the identi\214ed object and FEC encoding block.)54 420 Q
(The "\215ags" \214eld is currently used to indicate if the N)54 444 Q
-.4(AC)-.35 G 2.5(Kc).4 G(ontent applies to)-2.5 E F2(NORM_DATA)2.5 E F0
(content,)2.5 E F2(NORM_INFO)2.5 E F0(content, or)2.5 E 2.5(both. Thus,)
54 456 R(de\214ned \215ags in this \214eld include:)2.5 E .4 LW 530.585
478.5 77.815 478.5 DL 54.61(Flag V)124.925 488 R 140.39(alue Purpose)
-1.11 F 530.585 492.5 77.815 492.5 DL F2(NORM_NACK_SEGMENT)82.815 502 Q
F0(0x01)16.385 E(Indicates the listed se)237.585 502 Q
(gment\(s\) are required as repair)-.15 E(.)-.55 E 530.585 506.5 77.815
506.5 DL F2(NORM_NACK_BLOCK)82.815 516 Q F0(0x02)28.385 E
(Indicates the entire listed block\(s\) are required as repair)237.585
516 Q(.)-.55 E 530.585 520.5 77.815 520.5 DL F2(NORM_NACK_INFO)82.815
530 Q F0(0x04)34.385 E(Indicates the object')237.585 530 Q(s)-.55 E F2
(NORM_INFO)2.5 E F0(is required as repair)2.5 E(.)-.55 E 530.585 534.5
77.815 534.5 DL F2(NORM_NACK_OBJECT)82.815 544 Q F0(0x08)22.385 E
(Indicates the entire listed object\(s\) are required as repair)237.585
544 Q(.)-.55 E 530.585 548.5 77.815 548.5 DL 530.585 478.5 530.585 548.5
DL 77.815 478.5 77.815 548.5 DL 230.085 478.5 230.085 548.5 DL 192.315
478.5 192.315 548.5 DL(When the)54 574 Q F2(NORM_FLAG_SEGMENT)2.5 E F0(\
\215ag is set, the "object_transport_id", "fec_block_number" and "fec_s\
ymbol_id" \214elds)2.5 E
(are concatenated to determine which sets or ranges of indi)54 586 Q
(vidual)-.25 E F2(NORM_DATA)2.5 E F0(se)2.5 E
(gments are needed to repair complete)-.15 E(content at this recei)54
598 Q -.15(ve)-.25 G 3.6 -.55(r. W).15 H(hen the).55 E F2
(NORM_FLAG_BLOCK)2.5 E F0(\215ag is set, this indicates the recei)2.5 E
-.15(ve)-.25 G 2.5(ri).15 G 2.5(sc)-2.5 G(ompletely missing the)-2.5 E
(indicated coding block\(s\) and requires transmissions suf)54 610 Q
(\214cient to repair the indicated block\(s\) in their entirety)-.25 E 5
(.I)-.65 G 2.5(nt)-5 G(his case)-2.5 E
(the "fec_symbol_id" repair request \214elds are ignored.)54 622 Q
(When the)5 E F2(NORM_NACK_INFO)2.5 E F0
(\215ag is set, this indicates the recei)2.5 E -.15(ve)-.25 G 2.5(ri).15
G(s)-2.5 E(missing the)54 634 Q F2(NORM_INFO)2.5 E F0(se)2.5 E
(gment for the indicated "object_transport_id".)-.15 E(Note the)5 E F2
(NORM_NACK_INFO)2.5 E F0(may be set in)2.5 E(combination with the)54 646
Q F2(NORM_NACK_BLOCK)2.5 E F0(or)2.5 E F2(NORM_NACK_SEGMENT)2.5 E F0
(\215ags, or may be set alone.)2.5 E(When the)5 E F2(NORM_NACK_OBJECT)54
658 Q F0(\215ag is set, this indicates the recei)2.5 E -.15(ve)-.25 G
2.5(ri).15 G 2.5(sm)-2.5 G(issing the entire NormT)-2.5 E
(ransportObject referenced by the)-.35 E(Adamson, Borman, et al.)36 696
Q(Expires September 2003)110.05 E([P)118.25 E(age 26])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E 2.5("object_transport_id". This)54 84 R
(also implicitly requests an)2.5 E 2.5(ya)-.15 G -.25(va)-2.7 G(ilable)
.25 E/F1 10/Courier@0 SF(NORM_INFO)2.5 E F0
(for the NormObject, if applicable.)2.5 E(The)5 E("fec_block_number" an\
d "fec_symbol_id" \214elds are ignored when the \215ag)54 96 Q F1
(NORM_NACK_OBJECT)2.5 E F0(is set.)2.5 E(The "length" \214eld is gi)54
120 Q -.15(ve)-.25 G 2.5(n\().15 G(in bytes\) to indicate the length of\
 the list of repair request items or ranges.)-2.5 E(Multiple lists of)5
E(repair request items and/or ranges may be concatenated together withi\
n a single)54 132 Q F1(NORM_NACK)2.5 E F0(message.)2.5 E
(The "object_transport_id", "fec_block_number)54 156 Q 2.5(,a)-.4 G
(nd "fec_symbol_id" \214elds comprise repair request list items to be)
-2.5 E(interpreted according to the repair request "form" and "\215ags"\
 \214elds.)54 168 Q(As noted, when the "form" is)5 E F1
(NORM_NACK_RANGES)2.5 E F0(,)A(pairs of)54 180 Q/F2 10/Times-Italic@0 SF
(object_tr)2.5 E(ansport_id::fec_bloc)-.15 E(k_number::er)-.2 E(asur)
-.15 E(e_count)-.37 E F0(de\214ne each repair request list item.)2.5 E
/F3 10/Times-BoldItalic@0 SF(NORM_N)54 204 Q -.65(AC)-.3 G 2.5(KC).65 G
(ontent Examples:)-2.5 E F0(In Example 1, a list of indi)54 228 Q
(vidual)-.25 E F1(NORM_NACK_ITEM)2.5 E F0(repair requests is gi)2.5 E
-.15(ve)-.25 G 2.5(n. In).15 F(Example 2, a list of)2.5 E F1
(NORM_NACK_RANGE)54 240 Q F0(requests _and_ a single)2.5 E F1
(NORM_NACK_ITEM)2.5 E F0
(request are concatenated to illustrate the possible)2.5 E(content of a)
54 252 Q F1(NORM_NACK)2.5 E F0 2.5(message. Note)2.5 F
(that FEC coding block erasure counts are pro)2.5 E(vided in each case.)
-.15 E(The erasure)5 E(counts are not really necessary since the sender\
 can easily determine the erasure count while processing the N)54 264 Q
-.4(AC)-.35 G 2.5(Kc).4 G(ontent.)-2.5 E(Ho)54 276 Q(we)-.25 E -.15(ve)
-.25 G .8 -.4(r, t).15 H(he erasure count option may be useful for oper\
ation with Generic Router Assist \(GRA\).).4 E(Example 1:)54 300 Q F1
(NORM_NACK)54 312 Q F0(content for: Object 12, Coding Block 3, Se)2.5 E
(gments 2,5,8)-.15 E F1 114(0123)60 336 S 6
(01234567890123456789012345678901)60 348 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
360 Q 18(|f)54 372 S(orm = 3)-18 E 6(|f)24 G(lags = 0x01)-6 E 42(|l)12 G
6(ength =)-42 F 78(8|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
384 Q 18(|o)54 396 S(bject_transport_id = 12)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
408 Q 18(|f)54 420 S(ec_block_number\(lsb\) = 3)-18 E 24(|e)18 G 6
(rasure_count =)-24 F 54(3|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
432 Q 18(|f)54 444 S(orm = 1)-18 E 6(|f)24 G(lags = 0x01)-6 E 42(|l)12 G
6(ength =)-42 F 66(24 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
456 Q 18(|o)54 468 S(bject_transport_id = 12)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
480 Q 18(|f)54 492 S(ec_block_number \(lsb\) = 3)-18 E 24(|f)12 G 6
(ec_symbol_id =)-24 F 54(2|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
504 Q 18(|o)54 516 S(bject_transport_id = 12)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
528 Q 18(|f)54 540 S(ec_block_number \(lsb\) = 3)-18 E 24(|f)12 G 6
(ec_symbol_id =)-24 F 54(5|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
552 Q 18(|o)54 564 S(bject_transport_id = 12)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
576 Q 18(|f)54 588 S(ec_block_number \(lsb\) = 3)-18 E 24(|f)12 G 6
(ec_symbol_id =)-24 F 54(8|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
600 Q F0(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05
E([P)118.25 E(age 27])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(Example 2:)54 84 Q/F1 10/Courier@0 SF(NORM_NACK)54
96 Q F0(content for: Object 18 Coding Block 6, Se)2.5 E
(gments 5, 6, 7, 8, 9, 10; and Object 19)-.15 E F1(NORM_INFO)2.5 E F0
(and Coding Block 1, se)2.5 E(gment 3)-.15 E F1 114(0123)60 120 S 6
(01234567890123456789012345678901)60 132 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
144 Q 18(|f)54 156 S(orm = 3)-18 E 6(|f)24 G(lags = 0x01)-6 E 42(|l)12 G
6(ength =)-42 F 78(8|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
168 Q 18(|o)54 180 S(bject_transport_id = 18)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
192 Q 18(|f)54 204 S(ec_block_number \(lsb\) = 6)-18 E 24(|e)12 G 6
(rasure_count =)-24 F 54(6|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
216 Q 18(|f)54 228 S(orm = 2)-18 E 6(|f)24 G(lags = 0x01)-6 E 42(|l)12 G
6(ength =)-42 F 66(16 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
240 Q 18(|o)54 252 S(bject_transport_id = 18)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
264 Q 18(|f)54 276 S(ec_block_number \(lsb\) = 6)-18 E 24(|f)12 G 6
(ec_symbol_id =)-24 F 54(5|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
288 Q 18(|o)54 300 S(bject_transport_id = 18)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
312 Q 18(|f)54 324 S(ec_block_number \(lsb\) = 6)-18 E 24(|f)12 G 6
(ec_symbol_id =)-24 F 42(10 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
336 Q 18(|f)54 348 S(orm = 3)-18 E 6(|f)24 G(lags = 0x05)-6 E 42(|l)12 G
6(ength =)-42 F 78(8|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
360 Q 18(|o)54 372 S(bject_transport_id = 19)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
384 Q 18(|f)54 396 S(ec_block_number \(lsb\) = 1)-18 E 24(|e)12 G 6
(rasure_count =)-24 F 54(1|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
408 Q 18(|f)54 420 S(orm = 1)-18 E 6(|f)24 G(lags = 0x05)-6 E 48(|l)12 G
6(ength =)-48 F 72(8|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
432 Q 18(|o)54 444 S(bject_transport_id = 19)-18 E 18(|f)24 G
(ec_block_number \(msb\) = 0)-18 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
456 Q 18(|f)54 468 S(ec_block_number \(lsb\) = 1)-18 E 24(|f)12 G 6
(ec_symbol_id =)-24 F 54(3|)6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
480 Q/F2 10/Times-BoldItalic@0 SF(4.3.2 NORM_A)54 504 Q(CK Message)-.65
E F0(The)54 528 Q F1(NORM_ACK)2.5 E F0(message is primarily used as par\
t of NORM congestion control operation and round-trip timing)2.5 E 7.5
(measurement. The)54 540 R(generation of)2.5 E F1(NORM_ACK)2.5 E F0(mes\
sages for round-trip timing and congestion-control operation is describ\
ed)2.5 E(in Sections 5.5.1 and 5.5.2, respeccti)54 552 Q -.15(ve)-.25 G
(ly).15 E 5(.S)-.65 G
(ome applications may bene\214t from some limited form of positi)-5 E
-.15(ve)-.25 G(ackno)54 564 Q(wledgement for certain functions.)-.25 E
2.5(As)5 G(imple, scalable positi)-2.5 E .3 -.15(ve a)-.25 H(ckno).15 E
(wledgement scheme is de\214ned in Section 5.5.3)-.25 E(which can be le)
54 576 Q -.15(ve)-.25 G
(raged by protocol implementations when appropriate.).15 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 28])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-BoldItalic@0 SF(NORM_A)54 84 Q
(CK Message F)-.65 E(ormat)-.7 E/F2 10/Courier@0 SF 114(0123)60 108 S 6
(01234567890123456789012345678901)60 120 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
132 Q 24(|v)54 144 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
156 Q 162(|s)54 168 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
180 Q 162(|s)54 192 S 156(erver_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
204 Q 138(|g)54 216 S 132(rtt_response_sec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
228 Q 138(|g)54 240 S 126(rtt_response_usec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
252 Q 24(|c)54 264 S 12(c_flags |)-24 F 18(cc_rtt |)30 F 66(cc_loss |)72
F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
276 Q 72(|c)54 288 S 66(c_rate |)-72 F 6(cc_sequence |)12 F 12
(ack_type |)24 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
300 Q 150(|a)54 312 S(ck_content ...)-150 E(|)138 E F0
(The NORM common message header \214elds serv)54 336 Q 2.5(et)-.15 G
(heir usual purposes.)-2.5 E(The "serv)54 360 Q(er_id", "grtt_response"\
, "cc_\215ags", "cc_rtt", "cc_loss", "cc_rate", and "cc_sequence" \214e\
lds serv)-.15 E 2.5(et)-.15 G(he same purpose)-2.5 E
(as the corresponding \214elds in)54 372 Q F2(NORM_NACK)2.5 E F0
(messages.)2.5 E(The "ack_type" \214eld indicates the nature of the)54
396 Q F2(NORM_ACK)2.5 E F0 2.5(message. This)2.5 F
(directly corresponds to the "ack_type" \214eld of)2.5 E(the)54 408 Q F2
(NORM_CMD)2.5 E F0(\(A)A(CK_REQ\) message.)-.4 E
(The "ack_content" format is a function of the "ack_type".)54 432 Q(The)
7.5 E F2(NORM_ACK)2.5 E F0(\(CC\) message has no attached content.)A
(Only the)5 E F2(NORM_ACK)54 444 Q F0(header applies.)2.5 E
(In the case of)5 E F2(NORM_ACK)2.5 E F0(\(W)A -1.11(AT)-1.2 G
(ERMARK\), a speci\214c "ack_content" format is de\214ned:)1.11 E F1
(NORM_A)54 468 Q(CK\(W)-.65 E -.55(AT)-.74 G(ERMARK\) Ac).55 E 2.5(kC)
-.1 G(ontent)-2.5 E F2
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
492 Q 36(|o)54 504 S 30(bject_transport_id |)-36 F
(fec_block_number \(msb\))24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
516 Q 30(|f)54 528 S(ec_block_number \(lsb\))-30 E 48(|f)24 G 54
(ec_symbol_id |)-48 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
540 Q F0(The "object_transport_id", "fec_block_number", and "fec_symbol\
_id" are used by the recei)54 564 Q -.15(ve)-.25 G 2.5(rt).15 G 2.5(oa)
-2.5 G(ckno)-2.5 E(wledge a)-.25 E F2(NORM_CMD)54 576 Q F0(\(A)A
(CK_REQ\(W)-.4 E -1.11(AT)-1.2 G
(ERMARK\)\) transmitted by the sender identi\214ed by the "serv)1.11 E
(er_id" \214eld.)-.15 E(The "ack_content" of)54 600 Q F2(NORM_ACK)2.5 E
F0(messages for application-de\214ned "ack_type" v)2.5 E
(alues is speci\214c to the application b)-.25 E(ut is)-.2 E
(limited in size to a maximum the NormSe)54 612 Q
(gmentSize of the sender referenced by the "serv)-.15 E(er_id".)-.15 E
/F3 10/Times-Bold@0 SF(4.4 General Messages)36 636 Q F0
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-BoldItalic@0 SF(4.4.1 NORM_REPOR)54 84
Q(T)-.3 E F0
(This is an optional message generated by NORM participants.)54 108 Q
(This message could be used for periodic performance reports)5 E
(from recei)54 120 Q -.15(ve)-.25 G(rs in e).15 E
(xperimental NORM implementations.)-.15 E
(The format of this message is currently unde\214ned.)5 E(Experimental)5
E(NORM implementations may de\214ne NORM_REPOR)54 132 Q 2.5(Tf)-.6 G
(ormats as needed for test purposes.)-2.5 E/F2 10/Times-Bold@0 SF
(5.0 Functionality De\214nition)36 156 Q F0
(This section describes the detailed interactions of senders and recei)
54 180 Q -.15(ve)-.25 G(rs participating in a NORM session.).15 E 2.5
(As)5 G(imple synopsis)-2.5 E(of protocol operation is gi)54 192 Q -.15
(ve)-.25 G 2.5(ni).15 G 2.5(nt)-2.5 G(he follo)-2.5 E(wing items.)-.25 E
(1\))54 222 Q(The sender periodically transmits)77.33 222 Q/F3 10
/Courier@0 SF(NORM_CMD)2.5 E F0
(\(CC\) messages as needed to initialize and collect roundtrip)A
(timing and congestion control feedback from the recei)77.33 234 Q -.15
(ve)-.25 G 2.5(rs).15 G(et.)-2.5 E(2\))54 258 Q
(The sender transmits an ordinal set of NormObjects se)77.33 258 Q
(gmented in the form of)-.15 E F3(NORM_DATA)2.5 E F0(\(and optional)2.5
E F3(NORM_INFO)77.33 270 Q F0 2.5(\)m)C(essages labeled with NormT)-2.5
E(ransportIds and logically identi\214ed with FEC encoding block)-.35 E
(numbers and symbol identi\214ers.)77.33 282 Q(3\))54 306 Q(As recei)
77.33 306 Q -.15(ve)-.25 G(rs detect missing content from the sender).15
E 2.5(,t)-.4 G(he)-2.5 E 2.5(yi)-.15 G(nitiate repair requests with)-2.5
E F3(NORM_NACK)2.5 E F0 2.5(messages. Note)77.33 318 R(the recei)2.5 E
-.15(ve)-.25 G(rs track the sender').15 E 2.5(sm)-.55 G(ost recent)-2.5
E/F4 10/Times-Italic@0 SF(object_tr)77.33 330 Q(ansport_id::fec_bloc)
-.15 E(k_number::fec_symbol_id)-.2 E F0(transmit position and N)2.5 E
-.4(AC)-.35 G 2.5(K_).4 G(only_ for content)-2.5 E
(ordinally prior to that transmit position.)77.33 342 Q(The recei)5 E
-.15(ve)-.25 G(rs use random back).15 E(of)-.1 E 2.5(ft)-.25 G
(imeouts before generating)-2.5 E F3(NORM_NACK)77.33 354 Q F0
(messages and w)2.5 E
(ait an appropriate amount of time before repeating the)-.1 E F3
(NORM_NACK)2.5 E F0(if their)2.5 E(repair request is not satisi\214ed.)
77.33 366 Q(4\))54 390 Q(The sender aggre)77.33 390 Q -.05(ga)-.15 G
(tes repair requests from the recei).05 E -.15(ve)-.25 G 2.5(rs).15 G
(et and logically "re)-2.5 E(winds" to send appropriate)-.25 E
(repair messages.)77.33 402 Q(The sender sends repairs for the earliest\
 ordinal transmit position \214rst and maintains this)5 E
(ordinal repair transmission sequence.)77.33 414 Q(Pre)5 E
(viously untransmitted FEC parity content for the applicable FEC)-.25 E
(coding block is used for repair transmissions to the greatest e)77.33
426 Q(xtent possible.)-.15 E(If the sender e)5 E(xhausts its)-.15 E -.2
(av)77.33 438 S(ailable FEC parity content on multiple repair c)-.05 E
(ycles for the same coding block, it resorts to an e)-.15 E(xplicit)-.15
E(repair strate)77.33 450 Q(gy \(ag)-.15 E
(ain using parity content\) to complete repairs.)-.05 E(\(The use of e)5
E(xplicit repair is e)-.15 E(xpected to be)-.15 E(an e)77.33 462 Q
(xception in general protocol operation, b)-.15 E
(ut the possibility does e)-.2 E(xist for e)-.15 E(xtreme conditions\).)
-.15 E(The)5 E(sender immediately assumes transmission of ne)77.33 474 Q
2.5(wc)-.25 G(ontent once it has sent pending repair transmissions.)-2.5
E(5\))54 498 Q(The sender transmits)77.33 498 Q F3(NORM_CMD)2.5 E F0
(\(FLUSH\) messages when it reaches the end of ne)A(wly a)-.25 E -.25
(va)-.2 G(ilable transmit).25 E 2.5(content. Recei)77.33 510 R -.15(ve)
-.25 G(rs respond to the).15 E F3(NORM_CMD)2.5 E F0
(\(FLUSH\) messages with)A F3(NORM_NACK)2.5 E F0(transmissions)2.5 E
(\(follo)77.33 522 Q(wing the same suppression back)-.25 E(of)-.1 E 2.5
(ft)-.25 G(imeout strate)-2.5 E(gy as for data\) if the)-.15 E 2.5(yr)
-.15 G(equire further repair)-2.5 E(.)-.55 E(6\))54 546 Q(The sender tr\
ansmission rate is subject to rate control limits determined by congest\
ion control.)77.33 546 Q(Each sender)5 E
(in a NormSession maintains its o)77.33 558 Q
(wn independent congestion control state.)-.25 E(Recei)5 E -.15(ve)-.25
G(rs pro).15 E(vide congestion)-.15 E(control feedback in)77.33 570 Q F3
(NORM_NACK)2.5 E F0(and)2.5 E F3(NORM_ACK)2.5 E F0 2.5(messages. This)
2.5 F(feedback is controlled using suppression)2.5 E
(mechanism similar to that for)77.33 582 Q F3(NORM_NACK)2.5 E F0
(messages.)2.5 E(While the o)54 612 Q -.15(ve)-.15 G
(rall concept of the protocol is relati).15 E -.15(ve)-.25 G
(ly simple, there are details to each of these aspects that need to be)
.15 E(addressed for successful, rob)54 624 Q
(ust, and scalable operation.)-.2 E(Adamson, Borman, et al.)36 696 Q
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E/F1 10/Times-Bold@0 SF
(5.1 NORM Sender Initialization and T)36 84 Q(ransmission)-.74 E F0
(Upon startup, the NORM sender immediately be)54 108 Q(gins sending)-.15
E/F2 10/Courier@0 SF(NORM_CMD)2.5 E F0(\(CC\) messages to collect GR)A
(TT and other)-.6 E(information from the potential group.)54 120 Q
(If congestion control operation is enabled the NORM_CC_FLA)5 E(G_EN)-.4
E(ABLE MUST)-.35 E(be set.)54 132 Q
(Congestion control operation SHALL be observ)5 E
(ed at all times when operating in the general Internet.)-.15 E(Ev)5 E
(en if)-.15 E(congestion control operation is disabled at the sender)54
144 Q 2.5(,i)-.4 G 2.5(tm)-2.5 G
(ay be desirable to set the the NORM_CC_FLA)-2.5 E(G_EN)-.4 E(ABLE to)
-.35 E(proacti)54 156 Q -.15(ve)-.25 G
(ly collect feedback from the recei).15 E -.15(ve)-.25 G(rs to ha).15 E
.3 -.15(ve i)-.2 H(nput to GR).15 E(TT measurement prior to N)-.6 E -.4
(AC)-.35 G 2.5(Ki).4 G(nitiation.)-2.5 E(In some cases, applications ma\
y wish for the sender to also proceed with data transmission immediatel\
y)54 180 Q 5(.I)-.65 G 2.5(no)-5 G(ther cases, the)-2.5 E
(sender may wish to defer data transmission until it has recei)54 192 Q
-.15(ve)-.25 G 2.5(ds).15 G(ome feedback or request from the recei)-2.5
E -.15(ve)-.25 G 2.5(rs).15 G(et indicating)-2.5 E(that recei)54 204 Q
-.15(ve)-.25 G(rs are indeed present.).15 E(Note, in some applications \
\(e.g. web push\), this indication may come out-of-band with)5 E
(respect to the multicast session via other means.)54 216 Q
(The periodic transmission of)5 E F2(NORM_CMD)2.5 E F0
(\(CC\) messages may precede)A(actual data transmission in order to ha)
54 228 Q .3 -.15(ve i)-.2 H(nitial GR).15 E(TT measurement.)-.6 E(The N\
ORM protocol sender message headers contain all information necessary t\
o con\214gure recei)54 252 Q -.15(ve)-.25 G(rs for subsequent reliable)
.15 E 2.5(reception. This)54 264 R
(includes FEC coding parameters, the sender NormSe)2.5 E
(gmentSize, and other information.)-.15 E(Additionally)5 E(,)-.65 E
(applications may le)54 276 Q -.15(ve)-.25 G(rage the use of).15 E F2
(NORM_INFO)2.5 E F0
(messages associated with the session data objects in the session to)2.5
E(pro)54 288 Q(vide application-speci\214c conte)-.15 E
(xt information for the session and data being transmitted.)-.15 E
(The NORM sender be)54 312 Q(gins se)-.15 E
(gmenting application-enqueued data into)-.15 E F2(NORM_DATA)2.5 E F0
(se)2.5 E(gments and transmitting it to the)-.15 E 2.5(group. The)54 324
R(rate of transmission is controlled via the congestion control mechani\
sms described in this document or at a \214x)2.5 E(ed)-.15 E
(rate if desired for closed netw)54 336 Q(ork operations.)-.1 E
(The recei)5 E -.15(ve)-.25 G
(rs participating in the multicast group pro).15 E(vide feedback to the)
-.15 E(sender as needed.)54 348 Q(When the sender reaches the end of da\
ta it has enqueued for transmission or an)5 E 2.5(yp)-.15 G
(ending repairs, it)-2.5 E(transmits a series of)54 360 Q F2(NORM_CMD)
2.5 E F0(\(FLUSH\) messages at a rate of one per 2*GR)A(TT)-.6 E 5(.R)
-.74 G(ecei)-5 E -.15(ve)-.25 G(rs may respond to these).15 E F2
(NORM_CMD)54 372 Q F0
(\(FLUSH\) messages with additional repair requests.)A 2.5(Ap)5 G
(rotocol parameter ")-2.5 E F2(NORM_ROBUST_FACTOR)A F0(")A
(determines the number of \215ush messages sent.)54 384 Q(If recei)5 E
-.15(ve)-.25 G(rs request repair).15 E 2.5(,t)-.4 G(he repair is pro)
-2.5 E(vided and \215ushing occurs ag)-.15 E(ain at)-.05 E
(the end of repair transmission.)54 396 Q F1(5.2 NORM Recei)36 420 Q -.1
(ve)-.1 G 2.5(rI).1 G(nitialization and Reception)-2.5 E F0
(The NORM protocol is designed such that recei)54 444 Q -.15(ve)-.25 G
(rs may join and lea).15 E .3 -.15(ve t)-.2 H(he group at will.).15 E
(Ho)5 E(we)-.25 E -.15(ve)-.25 G .8 -.4(r, s).15 H(ome applications may)
.4 E(be constrained such that recei)54 456 Q -.15(ve)-.25 G(rs need to \
be members of the group prior to start of data transmission.).15 E
(NORM applications)5 E(may use dif)54 468 Q
(ferent policies to constrain the impact of ne)-.25 E 2.5(wr)-.25 G
(ecei)-2.5 E -.15(ve)-.25 G
(rs joining the group in the middle of a session.).15 E -.15(Fo)5 G(r)
.15 E -.15(ex)54 480 S(ample, a useful implementation polic).15 E 2.5
(yi)-.15 G 2.5(sf)-2.5 G(or ne)-2.5 E 2.5(wr)-.25 G(ecei)-2.5 E -.15(ve)
-.25 G(rs joining the group to restrain requesting repair of transport)
.15 E(objects in progress.)54 492 Q(The NORM sender implementation may \
wish to impose additional constraints to limit the ability of)5 E(recei)
54 504 Q -.15(ve)-.25 G
(rs to disrupt reliable multicast performance by joining, lea).15 E
(ving, and rejoining the group often.)-.2 E(Dif)5 E(ferent recei)-.25 E
-.15(ve)-.25 G(r).15 E("join policies" may be appropriate for dif)54 516
Q(ferent applications and/or scenarios.)-.25 E 2.5(Ad)5 G(ef)-2.5 E
(ault polic)-.1 E 2.5(yo)-.15 G 2.5(fa)-2.5 G(llo)-2.5 E(wing recei)-.25
E -.15(ve)-.25 G(rs to).15 E
(request repair only for coding blocks with a NormT)54 528 Q
(ransportId and FEC coding block number greater than or equal to the)
-.35 E(\214rst non-repair)54 540 Q F2(NORM_DATA)2.5 E F0(or)2.5 E F2
(NORM_INFO)2.5 E F0(message recei)2.5 E -.15(ve)-.25 G 2.5(du).15 G
(pon joining the group is RECOMMENDED for general)-2.5 E
(purpose operation.)54 552 Q F1(5.3 NORM Recei)36 576 Q -.1(ve)-.1 G 2.5
(rN).1 G -.55(AC)-2.7 G 2.5(KP).55 G -.18(ro)-2.5 G(cedur).18 E(e)-.18 E
F0(When the recei)54 600 Q -.15(ve)-.25 G 2.5(rd).15 G
(etects it is missing data from a sender')-2.5 E 2.5(sN)-.55 G
(ORM transmissions, it initiates its N)-2.5 E -.4(AC)-.35 G
(King procedure.).4 E(The)5 E -.35(NA)54 612 S(CKing procedure SHALL be\
 initiated _only_ at NormObject boundaries, FEC coding block boundaries\
, or upon receipt)-.05 E(of a)54 624 Q F2(NORM_CMD)2.5 E F0
(\(FLUSH\) or)A F2(NORM_CMD)2.5 E F0(\(A)A(CK_REQ\(W)-.4 E -1.11(AT)-1.2
G(ERMARK\)\) message.)1.11 E(The N)54 648 Q -.4(AC)-.35 G
(King procedure be).4 E(gins with a random back)-.15 E(of)-.1 E 2.5(ft)
-.25 G 2.5(imeout. The)-2.5 F(duration of the back)2.5 E(of)-.1 E 2.5
(ft)-.25 G(imeout is chosen using the)-2.5 E(Adamson, Borman, et al.)36
696 Q(Expires September 2003)110.05 E([P)118.25 E(age 31])-.15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E("RandomBack)54 84 Q(of)-.1 E(f" algorithm describ\
ed in the NORM Building Block document [15] using \()-.25 E/F1 10
/Courier@0 SF(K*GRTTsender)A F0 2.5(\)f)C(or the)-2.5 E("maxT)54 96 Q
(ime" parameter and the sender adv)-.35 E(ertised group size \()-.15 E
F1(GSIZEsender)A F0 2.5(\)a)C 2.5(st)-2.5 G(he "groupSize" parameter)
-2.5 E 5(.T)-.55 G(he back)-5 E(of)-.1 E(f)-.25 E -.1(fa)54 108 S
(ctor ").1 E F1(K)A F0 2.5("M)C(UST be greater than one to pro)-2.5 E
(vide for feedback suppression.)-.15 E 2.5(Av)5 G(alue of)-2.75 E F1 6
(K=4)2.5 G F0(is RECOMMENDED for the)-3.5 E(An)54 120 Q 2.5(yS)-.15 G
(ource Multicast \(ASM\) model while a v)-2.5 E(alue of)-.25 E F1 6(K=6)
2.5 G F0(is RECOMMENDED for Single Source Multicast \(SSM\))-3.5 E 2.5
(operation. Thus:)54 132 R F1
(T_backoff = RandomBackoff\(K*GRTTsender, GSIZEsender\))148.2 156 Q F0
(During this back)54 180 Q(of)-.1 E 2.5(ft)-.25 G(ime, the recei)-2.5 E
-.15(ve)-.25 G 2.5(ra).15 G(ccumulates e)-2.5 E
(xternal pending repair state from)-.15 E F1(NORM_NACK)2.5 E F0
(messages and)2.5 E F1(NORM_CMD)54 192 Q F0(\(REP)A(AIR_AD)-.92 E
(V\) messages recei)-.4 E -.15(ve)-.25 G 2.5(d. At).15 F
(the end of the back)2.5 E(of)-.1 E 2.5(ft)-.25 G(ime, the recei)-2.5 E
-.15(ve)-.25 G 2.5(rS).15 G(HALL generate a)-2.5 E F1(NORM_NACK)54 204 Q
F0(message only if the follo)2.5 E(wing conditions are met:)-.25 E(1\))
54 234 Q(The sender')77.33 234 Q 2.5(sc)-.55 G
(urrent transmit position \(in terms of)-2.5 E/F2 10/Times-Italic@0 SF
(object_tr)2.5 E(ansport_id::fec_bloc)-.15 E(k_number::fec_symbol_id)-.2
E F0(\))A -.15(ex)77.33 246 S
(ceeds the earliest repair position of the recei).15 E -.15(ve)-.25 G
-.55(r.).15 G(2\))54 270 Q(The repair state accumulated from)77.33 270 Q
F1(NORM_NACK)2.5 E F0(and)2.5 E F1(NORM_CMD)2.5 E F0(\(REP)A(AIR_AD)-.92
E(V\) messages do not equal or)-.4 E(supersede the recei)77.33 282 Q
-.15(ve)-.25 G(r').15 E 2.5(sr)-.55 G(epair needs.)-2.5 E
(If these conditions are met, the recei)54 312 Q -.15(ve)-.25 G 2.5(ri)
.15 G(mmediately generates a)-2.5 E F1(NORM_NACK)2.5 E F0
(message when the back)2.5 E(of)-.1 E 2.5(ft)-.25 G(imeout e)-2.5 E
(xpires.)-.15 E(The content of the)54 336 Q F1(NORM_NACK)2.5 E F0
(message contains repair request content be)2.5 E(ginning with lo)-.15 E
(west ordinal repair position for)-.25 E(the recei)54 348 Q -.15(ve)-.25
G 2.5(ru).15 G 2.5(pt)-2.5 G 2.5(ot)-2.5 G
(he most recently heard ordinal transmission position for the sender)
-2.5 E 5(.I)-.55 G 2.5(ft)-5 G(he size of the)-2.5 E F1(NORM_NACK)2.5 E
F0(content e)54 360 Q(xceeds the NormSe)-.15 E(gmentSize, the N)-.15 E
-.4(AC)-.35 G 2.5(Kc).4 G
(ontent is limited to that point so that the recei)-2.5 E -.15(ve)-.25 G
2.5(ro).15 G(nly generates a single)-2.5 E F1(NORM_NACK)54 372 Q F0
(message per N)2.5 E -.4(AC)-.35 G 2.5(Kc).4 G(ycle for a gi)-2.65 E
-.15(ve)-.25 G 2.5(ns).15 G(ender)-2.5 E(.)-.55 E -.15(Fo)54 396 S 2.5
(re).15 G(ach partially-recei)-2.5 E -.15(ve)-.25 G 2.5(dF).15 G
(EC coding block requiring repair)-2.5 E 2.5(,t)-.4 G(he recei)-2.5 E
-.15(ve)-.25 G 2.5(rS).15 G
(HALL, on its _\214rst_ repair attempt for the)-2.5 E
(block, request the parity portion of the FEC coding block be)54 408 Q
(ginning with the lo)-.15 E(west ordinal _parity_ "fec_symbol_id" and)
-.25 E(request the number of symbols corresponding to its data se)54 420
Q(gment erasure count for the block.)-.15 E(On _subsequent_ repair c)5 E
(ycles)-.15 E(for the same coding block, the recei)54 432 Q -.15(ve)-.25
G 2.5(rS).15 G(HALL request only those repair symbols from the \214rst \
set it has not yet recei)-2.5 E -.15(ve)-.25 G 2.5(du).15 G(p)-2.5 E
(to the remaining erasure count for that applicable coding block.)54 444
Q(Note that the sender may ha)5 E .3 -.15(ve p)-.2 H(ro).15 E
(vided other additional)-.15 E(parity se)54 456 Q
(gments for other recei)-.15 E -.15(ve)-.25 G
(rs that could also be used to satisfy the local recei).15 E -.15(ve)
-.25 G(r').15 E 2.5(se)-.55 G(rasure-\214lling needs.)-2.5 E
(In the case)5 E(where the erasure count for a partially-recei)54 468 Q
-.15(ve)-.25 G 2.5(dF).15 G(EC coding block e)-2.5 E
(xceeds the maximum number of parity symbols a)-.15 E -.25(va)-.2 G
(ilable).25 E(from the sender for the block \(as indicated by the)54 480
Q F1(NORM_DATA)2.5 E F0("fec_num_parity" \214eld\), the recei)2.5 E -.15
(ve)-.25 G 2.5(rS).15 G(HALL request all)-2.5 E -.2(av)54 492 S
(ailable parity se)-.05 E
(gments and the ordinally highest missing data se)-.15 E
(gments required to satisfy its erasure needs for the block.)-.15 E
(The goal of this strate)54 504 Q(gy is for the o)-.15 E -.15(ve)-.15 G
(rall recei).15 E -.15(ve)-.25 G 2.5(rs).15 G(et to request a lo)-2.5 E
(west common denominator set of repair symbols for a)-.25 E(gi)54 516 Q
-.15(ve)-.25 G 2.5(nF).15 G(EC coding block.)-2.5 E(This allo)5 E
(ws the sender to construct the most ef)-.25 E
(\214cient repair transmission se)-.25 E(gment set and enables)-.15 E
(ef)54 528 Q(fecti)-.25 E .3 -.15(ve N)-.25 H -.4(AC)-.2 G 2.5(Ks).4 G
(uppression among the recei)-2.5 E -.15(ve)-.25 G(rs e).15 E -.15(ve)
-.25 G 2.5(nw).15 G(ith uncorrelated pack)-2.5 E(et loss.)-.1 E
(This approach also requires no)5 E(synchronization among the recei)54
540 Q -.15(ve)-.25 G 2.5(rs).15 G
(et in their repair requests for the sender)-2.5 E(.)-.55 E -.15(Fo)54
564 S 2.5(rF).15 G
(EC coding blocks or NormObjects missing in their entirety)-2.5 E 2.5
(,t)-.65 G(he NORM recei)-2.5 E -.15(ve)-.25 G 2.5(rc).15 G
(onstructs repair requests with)-2.5 E F1(NORM_NACK_BLOCK)54 576 Q F0
(or)2.5 E F1(NORM_NACK_OBJECT)2.5 E F0(\215ags set as appropriate.)2.5 E
(The request for retransmission of)5 E F1(NORM_INFO)2.5 E F0(is)2.5 E
(accomplished by setting the)54 588 Q F1(NORM_NACK_INFO)2.5 E F0
(\215ag in a corresponding repair request.)2.5 E/F3 10/Times-Bold@0 SF
(5.4 NORM Sender N)36 612 Q -.55(AC)-.2 G 2.5(KP).55 G -.18(ro)-2.5 G
(cessing and Repair T).18 E(ransmission)-.74 E F0
(The principle goal of the sender is to mak)54 636 Q 2.5(ef)-.1 G(orw)
-2.5 E
(ard progress in the transmission of data its application has enqueued.)
-.1 E(Ho)54 648 Q(we)-.25 E -.15(ve)-.25 G .8 -.4(r, t).15 H
(he sender must occasionally "re).4 E
(wind" to satisfy the repair needs of recei)-.25 E -.15(ve)-.25 G
(rs who ha).15 E .3 -.15(ve N)-.2 H -.4(AC)-.2 G -.25(Ke).4 G 2.5
(d. Aggre).25 F -.05(ga)-.15 G(tion of).05 E(Adamson, Borman, et al.)36
696 Q(Expires September 2003)110.05 E([P)118.25 E(age 32])-.15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(multiple N)54 84 Q -.4(AC)-.35 G
(Ks is used to determine an optimal repair strate).4 E(gy when a N)-.15
E -.4(AC)-.35 G 2.5(Ke).4 G -.15(ve)-2.75 G(nt occurs.).15 E
(Since recei)5 E -.15(ve)-.25 G(rs initiate the).15 E -.35(NA)54 96 S(C\
K process on coding block or object boundaries, there is some loose de)
-.05 E(gree of synchronization of the repair process.)-.15 E/F1 10
/Times-BoldItalic@0 SF(5.4.1 NORM Sender Repair State Aggregation)54 120
Q F0(When a sender is in its normal state of transmitting ne)54 144 Q
2.5(wd)-.25 G(ata and recei)-2.5 E -.15(ve)-.25 G 2.5(saN).15 G -.4(AC)
-2.85 G(K, it be).4 E(gins a procedure to accumulate)-.15 E -.35(NA)54
156 S(CK repair state from)-.05 E/F2 10/Courier@0 SF(NORM_NACK)2.5 E F0
(messages before be)2.5 E(ginning repair transmissions.)-.15 E
(Note that this period of aggre)5 E -.05(ga)-.15 G(ting).05 E
(repair state does _not_ interfere with its ongoing transmission of ne)
54 168 Q 2.5(wd)-.25 G(ata.)-2.5 E
(The period of time during which the sender aggre)54 192 Q -.05(ga)-.15
G(tes).05 E F2(NORM_NACK)2.5 E F0(messages is equal to K*GR)2.5 E
(TT where "K" is the same)-.6 E(back)54 204 Q(of)-.1 E 2.5(fs)-.25 G
(caling v)-2.5 E(alue used by the recei)-.25 E -.15(ve)-.25 G
(rs and "GR).15 E(TT" is the sender')-.6 E 2.5(sc)-.55 G
(urrent estimate of the group')-2.5 E 2.5(sg)-.55 G(reatest round-trip)
-2.5 E 2.5(time. When)54 216 R(this period ends, the sender "re)2.5 E
(winds" by incorporating the accumulated repair state into its pending)
-.25 E(transmission state and be)54 228 Q
(gins transmitting repair messages, then continues with ne)-.15 E 2.5
(wt)-.25 G(ransmissions of an)-2.5 E 2.5(ye)-.15 G(nqueued data.)-2.5 E
(Also, at this point in time, the sender be)54 240 Q(gins a "holdof)-.15
E(f" timeout of 1*GR)-.25 E
(TT during which time the sender constrains itself)-.6 E
(from initiating a ne)54 252 Q 2.5(wr)-.25 G(epair aggre)-2.5 E -.05(ga)
-.15 G(tion c).05 E(ycle, e)-.15 E -.15(ve)-.25 G 2.5(ni).15 G(f)-2.5 E
F2(NORM_NACK)2.5 E F0(messages arri)2.5 E -.15(ve)-.25 G 5(.I).15 G 2.5
(fa)-5 G(dditional)-2.5 E F2(NORM_NACK)2.5 E F0(messages)2.5 E
(are recei)54 264 Q -.15(ve)-.25 G 2.5(dd).15 G(uring this hold-of)-2.5
E 2.5(fp)-.25 G(eriod, the sender will immediately incorporate these "l\
ate messages" into its pending)-2.5 E(transmission state ONL)54 276 Q
2.5(Yi)-1 G 2.5(ft)-2.5 G(he N)-2.5 E -.4(AC)-.35 G 2.5(Kc).4 G
(ontent is ordinally greater than the sender')-2.5 E 2.5(sc)-.55 G
(urrent transmission position.)-2.5 E(This)5 E("holdof)54 288 Q
(f" time allo)-.25 E(ws w)-.25 E
(orst case time for the sender to propag)-.1 E
(ate its current transmission sequence position to the group,)-.05 E
(thus a)54 300 Q -.2(vo)-.2 G(iding redundant repair transmissions.).2 E
(After the holdof)5 E 2.5(ft)-.25 G(imeout e)-2.5 E(xpires, a ne)-.15 E
2.5(wN)-.25 G -.4(AC)-2.85 G 2.5(Ka).4 G(ccumulation period can be)-2.5
E(be)54 312 Q(gun \(upon arri)-.15 E -.25(va)-.25 G 2.5(lo).25 G 2.5
(faN)-2.5 G -.4(AC)-2.85 G
(K\) in concert with the pending repair and ne).4 E 2.5(wd)-.25 G
(ata transmission.)-2.5 E(The sender repeats the same)5 E(process of in\
corporating accumulated repair state into its transmission plan during \
the the ne)54 324 Q 2.5(wa)-.25 G(ggre)-2.5 E -.05(ga)-.15 G
(tion period and).05 E(subsequently "re)54 336 Q
(winding" to transmit the lo)-.25 E(west ordinal repair data.)-.25 E F1
(5.4.2 NORM Sender FEC Repair T)54 360 Q(ransmission Strategy)-.37 E F0
(The NORM sender should le)54 384 Q -.15(ve)-.25 G
(rage transmission of FEC parity content for repair to the greatest e)
.15 E(xtent possible.)-.15 E(Recall that)5 E(the recei)54 396 Q -.15(ve)
-.25 G(rs use a strate).15 E(gy to request a lo)-.15 E
(west common denominator of e)-.25 E
(xplicit repair \(including parity content\) in the)-.15 E
(formation of their)54 408 Q F2(NORM_NACK)2.5 E F0 2.5(messages. Before)
2.5 F -.1(fa)2.5 G(lling back to e).1 E
(xplicitly satisfying all of the dif)-.15 E(ferent recei)-.25 E -.15(ve)
-.25 G(rs' repair).15 E(needs, the sender can mak)54 420 Q 2.5(eu)-.1 G
(se of the general erasure-\214lling capability of FEC-generated parity\
 se)-2.5 E 2.5(gments. The)-.15 F(sender can)2.5 E
(determine the maximum erasure \214lling needs for indi)54 432 Q
(vidual FEC coding blocks from the)-.25 E F2(NORM_NACK)2.5 E F0
(messages recei)2.5 E -.15(ve)-.25 G(d).15 E(during the repair aggre)54
444 Q -.05(ga)-.15 G(tion period.).05 E(Then, if the sender has a suf)5
E(\214cient number \(less than or equal to the maximum erasure)-.25 E
(count\) of pre)54 456 Q(viously unsent parity se)-.25 E(gments a)-.15 E
-.25(va)-.2 G(ilable for the applicable coding blocks, the sender can t\
ransmit these in lieu).25 E(of the speci\214c pack)54 468 Q
(ets the recei)-.1 E -.15(ve)-.25 G 2.5(rs).15 G(et has requested.)-2.5
E(Only after e)5 E(xhausting its supply of "fresh" \(unsent\) parity se)
-.15 E(gments for)-.15 E 2.5(ag)54 480 S -2.15 -.25(iv e)-2.5 H 2.5(nc)
.25 G(oding block should the sender resort to e)-2.5 E
(xplicit transmission of the recei)-.15 E -.15(ve)-.25 G 2.5(rs).15 G
(et')-2.5 E 2.5(sr)-.55 G(epair needs.)-2.5 E(In general, if a)5 E(suf)
54 492 Q(\214ciently po)-.25 E(werful FEC code is used, the need for e)
-.25 E(xplicit repair will be an e)-.15 E
(xception, and the ful\214llment of reliable)-.15 E
(multicast can be accomplished quite ef)54 504 Q(\214ciently)-.25 E 5
(.H)-.65 G -.25(ow)-5 G -2.15 -.25(ev e).25 H .8 -.4(r, t).25 H
(he ability to resort to e).4 E(xplicit repair allo)-.15 E
(ws the protocol to be)-.25 E(reliable under e)54 516 Q -.15(ve)-.25 G
2.5(nv).15 G(ery e)-2.65 E(xtreme circumstances.)-.15 E F2(NORM_DATA)54
540 Q F0
(messages sent as repair transmissions are \215agged with the NORM_FLA)
2.5 E(G_REP)-.4 E(AIR \215ag.)-.92 E(This allo)5 E(ws recei)-.25 E -.15
(ve)-.25 G(rs).15 E(to obe)54 552 Q 2.5(ya)-.15 G .3 -.15(ny p)-2.5 H
(olicies that limit ne).15 E 2.5(wr)-.25 G(ecei)-2.5 E -.15(ve)-.25 G
(rs from joining the reliable transmission on repair transmissions.).15
E 1.6 -.8(To f)54 576 T(acilitate operation with Generic Router Assist \
\(GRA\) [12], the sender can additionally \215ag).7 E F2(NORM_DATA)2.5 E
F0(transmissions)2.5 E(sent as e)54 588 Q
(xplicit repair with the NORM_FLA)-.15 E(G_EXPLICIT \215ag.)-.4 E
(The GRA router needs to only subcast a suf)5 E(\214cient count of)-.25
E(non-e)54 600 Q(xplicit parity repairs to satisfy the sub-tree')-.15 E
2.5(se)-.55 G(rasure \214lling needs for a gi)-2.5 E -.15(ve)-.25 G 2.5
(nF).15 G(EC coding block.)-2.5 E(When the sender has)5 E(resorted to e)
54 612 Q(xplicit repair)-.15 E 2.5(,t)-.4 G
(he GRA router will subcast all of the e)-2.5 E(xplicit repair pack)-.15
E(ets to those portions of the routing tree)-.1 E
(still requiring repair for a gi)54 624 Q -.15(ve)-.25 G 2.5(nc).15 G
(oding block.)-2.5 E(\(Note the GRA router will be required to conduct \
repair state accumulation)5 E
(for sub-routes in a manner similar to the sender')54 636 Q 2.5(sr)-.55
G(epair state accumulation in order to ha)-2.5 E .3 -.15(ve s)-.2 H(uf)
.15 E(\214cient information to perform)-.25 E(the subcasting.)54 648 Q
(Additionally)5 E 2.5(,t)-.65 G(he GRA router can perform additional)
-2.5 E F2(NORM_NACK)2.5 E F0(suppression/aggre)2.5 E -.05(ga)-.15 G
(tion as it conducts).05 E(Adamson, Borman, et al.)36 696 Q
(Expires September 2003)110.05 E([P)118.25 E(age 33])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(this repair state accumulation for NORM repair c)
54 84 Q(ycles\).)-.15 E/F1 10/Times-BoldItalic@0 SF
(5.4.3 NORM Sender NORM_CMD\(SQ)54 108 Q(UELCH\) Generation)-.1 E F0
(If the sender recei)54 132 Q -.15(ve)-.25 G 2.5(sa).15 G/F2 10
/Courier@0 SF(NORM_NACK)A F0(message for repair of data it is no longer\
 supporting, the sender generates a)2.5 E F2(NORM_CMD)54 144 Q F0(\(SQ)A
(UELCH\) message to adv)-.1 E(ertise its repair windo)-.15 E 2.5(wa)-.25
G(nd squelch an)-2.5 E 2.5(yr)-.15 G(ecei)-2.5 E -.15(ve)-.25 G
(rs from additional N).15 E -.4(AC)-.35 G(King of).4 E(in)54 156 Q -.25
(va)-.4 G(lid data.).25 E(The transmission rate of)5 E F2(NORM_CMD)2.5 E
F0(\(SQ)A(UELCH\) messages is limited to once per 2*GR)-.1 E(TT)-.6 E 5
(.T)-.74 G(he)-5 E("in)54 168 Q -.25(va)-.4 G
(lid_object_list" \(if applicable\) of the).25 E F2(NORM_CMD)2.5 E F0
(\(SQ)A(UELCH\) message SHALL be)-.1 E(gin with the lo)-.15 E(west)-.25
E("object_transport_id" from the in)54 180 Q -.25(va)-.4 G(lid).25 E F2
(NORM_NACK)2.5 E F0(messages recei)2.5 E -.15(ve)-.25 G 2.5(ds).15 G
(ince the last)-2.5 E F2(NORM_CMD)2.5 E F0(\(SQ)A(UELCH\) transmission.)
-.1 E(Lo)54 192 Q(wer ordinal in)-.25 E -.25(va)-.4 G
(lid "object_transport_ids" should be included only while the).25 E F2
(NORM_CMD)2.5 E F0(\(SQ)A(UELCH\) payload is less than)-.1 E
(the sender')54 204 Q 2.5(sN)-.55 G(ormSe)-2.5 E(gmentSize parameter)
-.15 E(.)-.55 E F1(5.4.4 NORM Sender NORM_CMD\(REP)54 228 Q(AIR_AD)-.85
E(V\) Generation)-.5 E F0(When a NORM sender recei)54 252 Q -.15(ve)-.25
G(s).15 E F2(NORM_NACK)2.5 E F0(messages from recei)2.5 E -.15(ve)-.25 G
(rs via unicast transmission, it uses).15 E F2(NORM_CMD)54 264 Q F0
(\(REP)A(AIR_AD)-.92 E(V\) messages to adv)-.4 E
(ertise its accumulated repair state to the recei)-.15 E -.15(ve)-.25 G
2.5(rs).15 G(et since the recei)-2.5 E -.15(ve)-.25 G 2.5(rs).15 G
(et is not)-2.5 E
(directly sharing their repair needs via multicast communication.)54 276
Q(The)5 E F2(NORM_CMD)2.5 E F0(\(REP)A(AIR_AD)-.92 E
(V\) message is multicast to)-.4 E(the recei)54 288 Q -.15(ve)-.25 G 2.5
(rs).15 G(et by the sender)-2.5 E 5(.T)-.55 G(he payload portion of thi\
s message has content in the same format as the)-5 E F2(NORM_NACK)2.5 E
F0(recei)54 300 Q -.15(ve)-.25 G 2.5(rm).15 G(essage payload.)-2.5 E
(Recei)5 E -.15(ve)-.25 G(rs are then able to perform feedback suppress\
ion in the same manner as with).15 E F2(NORM_NACK)54 312 Q F0
(messages directly recei)2.5 E -.15(ve)-.25 G 2.5(df).15 G
(rom other recei)-2.5 E -.15(ve)-.25 G 2.5(rs. Note).15 F
(the sender does not merely retransmit N)2.5 E -.4(AC)-.35 G 2.5(Kc).4 G
(ontent it)-2.5 E(recei)54 324 Q -.15(ve)-.25 G(s, b).15 E
(ut instead transmits a representation of its aggre)-.2 E -.05(ga)-.15 G
(ted repair state.).05 E(The transmission of)5 E F2(NORM_CMD)54 336 Q F0
(\(REP)A(AIR_AD)-.92 E
(V\) messages are subject to the sender transmit rate limit and NormSe)
-.4 E(gmentSize limitation.)-.15 E(When)5 E(the)54 348 Q F2(NORM_CMD)2.5
E F0(\(REP)A(AIR_AD)-.92 E(V\) message is of maximum size, recei)-.4 E
-.15(ve)-.25 G(rs SHALL consider the maximum ordinal).15 E
(transmission position v)54 360 Q(alue embedded in the message as the s\
enders "current" transmission position and suppress requests)-.25 E
(for ordinally higher repair)54 372 Q 5(.F)-.55 G
(or congestion control operation, the)-5.15 E F2(NORM_CMD)2.5 E F0
(\(REP)A(AIR_AD)-.92 E(V\) \214elds of "cc_\215ags", "cc_rtt",)-.4 E
(and "cc_rate" contain the "w)54 384 Q(orst case" v)-.1 E(alues recei)
-.25 E -.15(ve)-.25 G 2.5(df).15 G(or each \214eld since the last)-2.5 E
F2(NORM_CMD)2.5 E F0(\(REP)A(AIR_AD)-.92 E(V\) transmission.)-.4 E
(This means the minimum recei)54 396 Q -.15(ve)-.25 G 2.5(d").15 G
(cc_rate" and the set of "cc_\215ag" v)-2.5 E
(alues resulting in the most suppression \(i.e. the)-.25 E F2
(NORM_CC_FLAG_RTT)54 408 Q F0(\215ag is unset if _an)2.5 E
(y_ congestion control feedback w)-.15 E(as recei)-.1 E -.15(ve)-.25 G
2.5(dw).15 G(ith that \215ag unset since the last)-2.5 E F2(NORM_CMD)54
420 Q F0(\(REP)A(AIR_AD)-.92 E(V\) transmission\).)-.4 E/F3 10
/Times-Bold@0 SF(5.5 Additional NORM Pr)36 444 Q(otocol Mechanisms)-.18
E F0(In addition to the principal function of data content transmission\
 and repair)54 468 Q 2.5(,t)-.4 G
(here are some other protocol mechanisms that)-2.5 E
(help NORM to adapt to netw)54 480 Q(ork conditions and play f)-.1 E
(airly with other coe)-.1 E(xistent protocols.)-.15 E F1
(5.5.1 NORM Greatest Round-trip T)54 504 Q(ime \(GR)-.37 E
(TT\) Collection)-.3 E F0 -.15(Fo)54 528 S 2.5(rN).15 G(ORM recei)-2.5 E
-.15(ve)-.25 G(rs to appropriately scale back).15 E(of)-.1 E 2.5(ft)-.25
G(imeouts and the senders to use proper corresponding timeouts, the)-2.5
E(participants must agree on a common timeout basis.)54 540 Q
(Each NORM sender monitors the round-trip time of acti)5 E .3 -.15(ve r)
-.25 H(ecei).15 E -.15(ve)-.25 G(rs).15 E
(and determines the group greatest round-trip time \(GR)54 552 Q 2.5
(TT\). The)-.6 F(sender adv)2.5 E(ertises this GR)-.15 E
(TT estimate in e)-.6 E -.15(ve)-.25 G(ry message it).15 E
(transmits so that recei)54 564 Q -.15(ve)-.25 G(rs ha).15 E .3 -.15
(ve t)-.2 H(his v).15 E(alue a)-.25 E -.25(va)-.2 G
(ilable for scaling their timers.).25 E 1.6 -.8(To m)5 H
(easure the current GR).8 E(TT)-.6 E 2.5(,t)-.74 G(he sender)-2.5 E
(periodically sends)54 576 Q F2(NORM_CMD)2.5 E F0
(\(CC\) messages which contain a locally generated timestamp.)A(Recei)5
E -.15(ve)-.25 G(rs are e).15 E(xpected to)-.15 E
(record this timestamp along with the time the)54 588 Q F2(NORM_CMD)2.5
E F0(\(CC\) message is recei)A -.15(ve)-.25 G 2.5(d. Then,).15 F
(when the recei)2.5 E -.15(ve)-.25 G(rs generate).15 E
(feedback messages to the sender)54 600 Q 2.5(,a)-.4 G 2.5(na)-2.5 G
(djusted v)-2.5 E
(ersion of the sender timestamp is embedded in the feedback message)-.15
E(\()54 612 Q F2(NORM_NACK)A F0(or)2.5 E F2(NORM_ACK)2.5 E F0 2.5
(\). The)B(adjustment adds the amount of time the recei)2.5 E -.15(ve)
-.25 G 2.5(rh).15 G(eld the timestamp before generating)-2.5 E
(its response.)54 624 Q(Upon receipt of this adjusted timestamp, the se\
nder is able to calculate the round-trip time to that recei)5 E -.15(ve)
-.25 G -.55(r.).15 G(The round-trip time for each recei)54 648 Q -.15
(ve)-.25 G 2.5(ri).15 G 2.5(sf)-2.5 G
(ed into an algorithm that weights and smooths the v)-2.5 E
(alues for a conserv)-.25 E(ati)-.25 E .3 -.15(ve e)-.25 H(stimate).15 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 34])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(of the GR)54 84 Q(TT)-.6 E 5(.T)-.74 G(he algorit\
hm and methodology is described in the NORM Building Block document [11\
] in the section)-5 E(entitled "One-to-Man)54 96 Q 2.5(yS)-.15 G
(ender GR)-2.5 E(TT Measurement".)-.6 E 2.5(Ac)5 G(onserv)-2.5 E(ati)
-.25 E .3 -.15(ve e)-.25 H
(stimate helps feedback suppression at a small cost in).15 E -.15(ove)54
108 S(rall protocol repair delay).15 E 5(.T)-.65 G(he sender')-5 E 2.5
(sc)-.55 G(urrent estimate of GR)-2.5 E(TT is adv)-.6 E
(ertised in the "grtt" \214eld found in all NORM)-.15 E
(sender messages.)54 120 Q(The adv)5 E(ertised GR)-.15 E
(TT is also limited to be at least as big as the nominal inter)-.6 E
(-pack)-.2 E(et transmission time)-.1 E(gi)54 132 Q -.15(ve)-.25 G 2.5
(nt).15 G(he sender')-2.5 E 2.5(sc)-.55 G(urrent transmission rate.)-2.5
E(The reason for this additional limit is to k)5 E(eep the recei)-.1 E
-.15(ve)-.25 G 2.5(rs).15 G(ome)-2.5 E(what "e)-.25 E -.15(ve)-.25 G(nt)
.15 E(dri)54 144 Q -.15(ve)-.25 G
(n" by making sure the sender has had adequate time to generate an).15 E
2.5(yr)-.15 G(esponse to repair requests from recei)-2.5 E -.15(ve)-.25
G(rs gi).15 E -.15(ve)-.25 G(n).15 E(transmit rate limitations due to c\
ongestion control or con\214guration.)54 156 Q(When the NORM_CC_FLA)54
180 Q(G_EN)-.4 E(ABLE is set in)-.35 E/F1 10/Courier@0 SF(NORM_CMD)2.5 E
F0(\(CC\) messages, the recei)A -.15(ve)-.25 G(rs respond to).15 E F1
(NORM_CMD)2.5 E F0(\(CC\))A(messages as described in Section 5.5.2, "NO\
RM Congestion Control Operation".)54 192 Q(The)5 E F1(NORM_CMD)2.5 E F0
(\(CC\) messages are)A(periodically generated by the sender as describe\
d for congestion control operation.)54 204 Q(This pro)5 E
(vides for acti)-.15 E -.15(ve)-.25 G 2.5(,b).15 G(ut controlled,)-2.7 E
(feedback from the group in the form of)54 216 Q F1(NORM_ACK)2.5 E F0
(messages and can pro)2.5 E(vide GR)-.15 E(TT feedback e)-.6 E -.15(ve)
-.25 G 2.5(ni).15 G 2.5(fn)-2.5 G(o)-2.5 E F1(NORM_NACK)2.5 E F0
(messages are being sent.)54 228 Q
(If operating without congestion control in a closed netw)5 E(ork, the)
-.1 E F1(NORM_CMD)2.5 E F0(\(CC\) messages may be)A
(sent periodically with the NORM_CC_FLA)54 240 Q(G_EN)-.4 E
(ABLE \215ag cleared.)-.35 E(In this case, recei)5 E -.15(ve)-.25 G
(rs will only pro).15 E(vide GR)-.15 E(TT)-.6 E
(measurement feedback when)54 252 Q F1(NORM_NACK)2.5 E F0
(messages are generated as no)2.5 E F1(NORM_ACK)2.5 E F0
(messages are generated in response to)2.5 E(the)54 264 Q F1(NORM_CMD)
2.5 E F0 2.5(\(CC\). In)B(this case, the)2.5 E F1(NORM_CMD)2.5 E F0
(\(CC\) messages may be sent less frequently)A 2.5(,a)-.65 G 2.5(sl)-2.5
G(ittle as once per minute, to)-2.5 E(conserv)54 276 Q 2.5(en)-.15 G
(etw)-2.5 E(ork capacity)-.1 E 5(.N)-.65 G(ote that the NORM_CC_FLA)-5 E
(G_EN)-.4 E(ABLE can also be set to acti)-.35 E -.15(ve)-.25 G
(ly solicit R).15 E(TT feedback)-.6 E(from the recei)54 288 Q -.15(ve)
-.25 G 2.5(rg).15 G(roup per congestion control operation e)-2.5 E -.15
(ve)-.25 G 2.5(nt).15 G
(hough the sender may not be observing congestion control)-2.5 E
(rate adjustment.)54 300 Q(NORM operation without congestion control sh\
ould only be considered in closed netw)5 E(orks.)-.1 E/F2 10
/Times-BoldItalic@0 SF(5.5.2 NORM Congestion Control Operation)54 324 Q
F0(This section describes congestion control operation for the NORM pro\
tocol.)54 348 Q(The supporting NORM message formats and)5 E(approach de\
scribed here are an adaptation of the equation-based TCP-Friendly Multi\
cast Congestion Control \(TFMCC\))54 360 Q
(approach described in [18] and [21].)54 372 Q -.4(Wi)5 G
(th this TFMCC-based approach, the transmission rate of NORM senders is)
.4 E(controlled in a rate-based manner as opposed to windo)54 384 Q
(w-based congestion control algorithms as in TCP)-.25 E 5(.H)-1.11 G
-.25(ow)-5 G -2.15 -.25(ev e).25 H .8 -.4(r, i).25 H 2.5(ti).4 G(s)-2.5
E(possible that the NORM protocol message set may alternati)54 396 Q
-.15(ve)-.25 G(ly be used to support a windo).15 E
(w-based multicast congestion)-.25 E(control scheme such as PGMCC [22].)
54 408 Q(The details of that alternati)5 E .3 -.15(ve m)-.25 H
(ay be described separately or in a future re).15 E(vision of)-.25 E
(this document.)54 420 Q(In either case \(rate-based TFMCC or windo)5 E
(w-based PGMCC\), successful control of sender transmission)-.25 E
(depends upon collection of sender)54 432 Q(->recei)-.2 E -.15(ve)-.25 G
2.5(rp).15 G(ack)-2.5 E(et loss estimates and sender<->recei)-.1 E -.15
(ve)-.25 G 2.5(rR).15 G(TT to identify the congestion)-3.1 E(control bo\
ttleneck path\(s\) within the multicast topology and adjust the sender \
rate accordingly)54 444 Q 5(.T)-.65 G(he recei)-5 E -.15(ve)-.25 G 2.5
(rw).15 G(ith loss and)-2.5 E -.6(RT)54 456 S 2.5(Te).6 G
(stimates that correspond to the lo)-2.5 E(west result transmission rat\
e is identi\214ed as the "current limiting recei)-.25 E -.15(ve)-.25 G
(r" \(CLR\).).15 E(The steady-state sender transmission rate, to be "fr\
iendly" with competing TCP \215o)54 480 Q(ws is calculated as:)-.25 E F1
(S)288 504 Q(Rsender = ------------------------------------------------\
---------------)54 516 Q(tRTT * \(sqrt\(\(2/3\)*p\) + 12 * sqrt\(\(3/8\
\)*p\) * p * \(1 + 32*\(p^2\)\)\))114 528 Q F0(where)106.5 540 Q 2.5(S=)
69.51 570 S(Nominal transmitted pack)88.21 570 Q
(et size. \(The "nominal" pack)-.1 E
(et size is determined by the sender as an)-.1 E -.15(ex)88.21 582 S
(ponentially weighted mo).15 E(ving a)-.15 E -.15(ve)-.2 G
(rage \(EWMA\) of transmitted pack).15 E(et sizes to account for v)-.1 E
(ariable)-.25 E(message sizes\).)88.21 594 Q(tR)54 618 Q(TT =)-.6 E
(The R)88.21 618 Q(TT estimate of the current "current limiting recei)
-.6 E -.15(ve)-.25 G(r" \(CLR\).).15 E 2.5(p=)70.07 642 S(The loss e)
88.21 642 Q -.15(ve)-.25 G(nt fraction of the CLR.).15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E 1.6 -.8(To s)54 84 T(upport congestion control fe\
edback collection and operation, the NORM sender periodically transmits)
.8 E/F1 10/Courier@0 SF(NORM_CMD)2.5 E F0(\(CC\))A(command messages.)54
96 Q(The GR)5 E
(TT is determined from congestion control feedback included in N)-.6 E
-.4(AC)-.35 G(Ks and A).4 E(CKs from the)-.4 E(recei)54 108 Q -.15(ve)
-.25 G 2.5(rs).15 G 2.5(et. The)-2.5 F
(NORM_CMD\(CC\) messages are multiple)2.5 E -.15(xe)-.15 G 2.5(dw).15 G
(ith NORM data and repair transmissions and serv)-2.5 E 2.5(es)-.15 G
-2.15 -.25(ev e)-2.5 H(ral).25 E(purposes:)54 120 Q(1\))54 150 Q
(Stimulate e)67.33 150 Q(xplicit feedback from the general recei)-.15 E
-.15(ve)-.25 G 2.5(rs).15 G
(et to collect congestion control information.)-2.5 E(2\))54 174 Q
(Communicate state to the recei)67.33 174 Q -.15(ve)-.25 G 2.5(rs).15 G
(et on the sender')-2.5 E 2.5(sc)-.55 G
(urrent congestion control status including details of)-2.5 E(the CLR.)
67.33 186 Q(3\))54 210 Q(Initiate rapid \(immediate\) feedback from the\
 CLR in order to closely track the dynamics of congestion)67.33 210 Q
(control for that "w)67.33 222 Q(orst path" in the sender)-.1 E(->recei)
-.2 E -.15(ve)-.25 G 2.5(rm).15 G(ulticast topology)-2.5 E(.)-.65 E
(The format of the)54 252 Q F1(NORM_CMD)2.5 E F0
(\(CC\) message is describe in Section 4.2.3 of this document.)A(The)5 E
F1(NORM_CMD)2.5 E F0(\(CC\) message)A(contains information to allo)54
264 Q 2.5(wf)-.25 G(or determination of sender<->recei)-2.5 E -.15(ve)
-.25 G 2.5(rR).15 G(TTs, to inform the group of the congestion control)
-3.1 E(CLR, and to pro)54 276 Q(vide feedback of indi)-.15 E(vidual R)
-.25 E(TT information to recei)-.6 E -.15(ve)-.25 G(rs in the group.).15
E(The)5 E F1(NORM_CMD)2.5 E F0(\(CC\) also pro)A(vides)-.15 E(for e)54
288 Q(xciting feedback from a set of potential limiting recei)-.15 E
-.15(ve)-.25 G 2.5(r\().15 G
(PLR\) nodes that may be determined administrati)-2.5 E -.15(ve)-.25 G
(ly or).15 E
(possibly algorithmically based on congestion control feedback.)54 300 Q
(The details of PLR selection are not discussed in this)5 E(document.)54
312 Q/F2 10/Times-BoldItalic@0 SF 2.5(5.5.2.1 NORM_CMD\(CC\))54 336 R
-.37(Tr)2.5 G(ansmission).37 E F0(The)54 360 Q F1(NORM_CMD)2.5 E F0(\(C\
C\) message is tranmitted periodically by the sender along with its nor\
mal data transmission.)A(Note that)5 E(the repeated transmission of)54
372 Q F1(NORM_CMD)2.5 E F0(\(CC\) messages may be initiated some time b\
efore transmission of user data content)A(at session startup.)54 384 Q(\
This may be done to collect some estimation of the current state of the\
 multicast topology with respect to)5 E(group and indi)54 396 Q
(vidual R)-.25 E(TT and congestion control state.)-.6 E(A)54 420 Q F1
(NORM_CMD)2.5 E F0
(\(CC\) message is immediately transmitted at sender startup.)A
(The interv)5 E(al of subsequent)-.25 E F1(NORM_CMD)2.5 E F0(\(CC\))A
(message transmission is determined as follo)54 432 Q(ws:)-.25 E(1\))54
462 Q(By def)67.33 462 Q(ault, the interv)-.1 E
(al is set according to the current sender GR)-.25 E(TT estimate.)-.6 E
2.5(As)5 G(tartup GR)-2.5 E(TT of 0.5)-.6 E
(seconds is recommended when no feedback has yet been recei)67.33 474 Q
-.15(ve)-.25 G 2.5(df).15 G(rom the group.)-2.5 E(2\))54 498 Q
(If a CLR has been identi\214ed \(based on pre)67.33 498 Q(vious recei)
-.25 E -.15(ve)-.25 G 2.5(rf).15 G(eedback\), the interv)-2.5 E
(al is the sender<->recei)-.25 E -.15(ve)-.25 G(r).15 E -.6(RT)67.33 510
S 2.5(Tf).6 G(or the CLR.)-2.5 E(3\))54 534 Q(Additionally)67.33 534 Q
2.5(,i)-.65 G 2.5(ft)-2.5 G(he interv)-2.5 E
(al of nominal data message transmission is greater than the GR)-.25 E
(TT or CLR R)-.6 E(TT)-.6 E(interv)67.33 546 Q(al, the)-.25 E F1
(NORM_CMD)2.5 E F0(\(CC\) interv)A(al is set to this greater v)-.25 E
2.5(alue. This)-.25 F(ensures that the transmission of this)2.5 E
(control message is not done to the e)67.33 558 Q
(xclusion of user data transmission.)-.15 E(The)54 588 Q F1(NORM_CMD)2.5
E F0(\(CC\) "cc_sequence" \214eld is incremented with each transmission\
 of a)A F1(NORM_CMD)2.5 E F0(\(CC\) command.)A(The)5 E
(greatest "cc_sequence" recently recei)54 600 Q -.15(ve)-.25 G 2.5(db)
.15 G 2.5(yr)-2.5 G(ecei)-2.5 E -.15(ve)-.25 G
(rs is included in their feedback to the sender).15 E 5(.T)-.55 G
(his allo)-5 E(ws the sender to)-.25 E
(determine the "age" of feedback to assist in congestion a)54 612 Q -.2
(vo)-.2 G(idance.).2 E(The sender adv)54 636 Q(ertises its current tran\
smission rate in the "send_rate" \214eld of the)-.15 E F1(NORM_CMD)2.5 E
F0(\(CC\) message.)A(This rate)5 E(information is used by recei)54 648 Q
-.15(ve)-.25 G(rs to bias the timing of e).15 E
(xplicit feedback and to initialize loss estimation during congestion)
-.15 E(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 36])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(control startup or restart.)54 84 Q
(The "cc_node_list" contains a list of entries identifying recei)54 108
Q -.15(ve)-.25 G
(rs and their current congestion control state \(status "\215ags",).15 E
("rtt" and "loss" estimates\).)54 120 Q
(The list may be empty if the sender has not yet recei)5 E -.15(ve)-.25
G 2.5(da).15 G .3 -.15(ny f)-2.5 H(eedback from the group.).15 E(If the)
5 E(sender has recei)54 132 Q -.15(ve)-.25 G 2.5(df).15 G
(eedback, the list will minimally contain an entry identifying the CLR.)
-2.5 E(A)5 E/F1 10/Courier@0 SF(NORM_CC_FLAG_CLR)2.5 E F0(\215ag)2.5 E
-.25(va)54 144 S(lue is pro).25 E
(vided for the "cc_\215ags" \214eld to identify the CLR entry)-.15 E 5
(.I)-.65 G 2.5(ti)-5 G 2.5(sr)-2.5 G
(ecommended that the CLR entry be the \214rst in the)-2.5 E
(list for implementation ef)54 156 Q(\214cienc)-.25 E 3.8 -.65(y. A)-.15
H(dditional entries in the list are used to pro).65 E(vide sender)-.15 E
(-measured indi)-.2 E(vidual R)-.25 E(TT)-.6 E(estimates to recei)54 168
Q -.15(ve)-.25 G(rs in the group.).15 E(The number of additional entrie\
s in this list is dependent upon the percentage of control)5 E(traf)54
180 Q(\214c the sender application is willing to send with respect to u\
ser data message transmissions.)-.25 E(More entries in the list may)5 E
(allo)54 192 Q 2.5(wt)-.25 G(he sender to be more responsi)-2.5 E .3
-.15(ve t)-.25 H 2.5(oc).15 G(ongestion control dynamics.)-2.5 E
(The length of the list may be dynamically)5 E(determined according to \
the current transmission rate and scheduling of)54 204 Q F1(NORM_CMD)2.5
E F0(\(CC\) messages.)A(The maximum length)5 E
(of the list corresponds to the sender')54 216 Q 2.5(s")-.55 G(NormSe)
-2.5 E(gmentSize" parameter for the session.)-.15 E
(The inclusion of additional entries in)5 E(the list based on recei)54
228 Q -.15(ve)-.25 G 2.5(rf).15 G(eedback are prioritized with follo)
-2.5 E(wing rules:)-.25 E(1\))54 258 Q(Recei)67.33 258 Q -.15(ve)-.25 G
(rs that ha).15 E .3 -.15(ve n)-.2 H(ot yet been pro).15 E(vided R)-.15
E(TT feedback get \214rst priority)-.6 E 5(.O)-.65 G 2.5(ft)-5 G
(hese, those with the greatest)-2.5 E(loss fraction recei)67.33 270 Q .3
-.15(ve p)-.25 H(recedence for list inclusion.).15 E(2\))54 294 Q
(Secondly)67.33 294 Q 2.5(,r)-.65 G(ecei)-2.5 E -.15(ve)-.25 G
(rs that ha).15 E .3 -.15(ve p)-.2 H(re).15 E(viously been pro)-.25 E
(vided R)-.15 E(TT are included with)-.6 E(recei)5 E -.15(ve)-.25 G
(rs yielding the lo).15 E(west)-.25 E
(calculated congestion rate getting precedence.)67.33 306 Q
(There are also "cc_\215ag" v)54 336 Q(alues in addition to)-.25 E F1
(NORM_CC_FLAG_CLR)2.5 E F0
(that are used for other congestion control functions.)2.5 E(The)54 348
Q F1(NORM_CC_FLAG_CLR)2.5 E F0(\215ag v)2.5 E
(alue is used to mark additional recei)-.25 E -.15(ve)-.25 G
(rs from which the sender w).15 E(ould lik)-.1 E 2.5(et)-.1 G 2.5(oh)
-2.5 G -2.25 -.2(av e)-2.5 H(immediate, non-suppressed feedback.)54 360
Q(These may be recei)5 E -.15(ve)-.25 G
(rs which the sender algorithmically identi\214ed as potential,).15 E
(future CLRs or which ha)54 372 Q .3 -.15(ve b)-.2 H(een pre-con\214gur\
ed as potential congestion control points in the netw).15 E 2.5
(ork. The)-.1 F F1(NORM_CC_FLAG_RTT)54 384 Q F0(indicates the v)2.5 E
(alidity of the "cc_rtt" \214eld for the associated recei)-.25 E -.15
(ve)-.25 G 2.5(rn).15 G 2.5(ode. Normally)-2.5 F 2.5(,t)-.65 G
(his \215ag will)-2.5 E(be set since the recei)54 396 Q -.15(ve)-.25 G
(rs in the list will typically be recei).15 E -.15(ve)-.25 G
(rs from which the sender has recei).15 E -.15(ve)-.25 G 2.5(df).15 G
2.5(eedback. Ho)-2.5 F(we)-.25 E -.15(ve)-.25 G .8 -.4(r, i).15 H 2.5
(nt).4 G(he)-2.5 E(case that the NORM sender has been pre-con\214gured \
with a set of PLR nodes, feedback from those recei)54 408 Q -.15(ve)-.25
G(rs may not yet).15 E(ha)54 420 Q .3 -.15(ve b)-.2 H(een collected and\
 thus the "cc_rtt" and "cc_rate" \214elds do not contain v).15 E(alid v)
-.25 E(alues.)-.25 E/F2 10/Times-BoldItalic@0 SF 2.5
(5.5.2.2 NORM_CMD\(CC\))54 444 R -1(Fe)2.5 G(edbac)1 E 2.5(kR)-.1 G
(esponse)-2.5 E F0(Recei)54 468 Q -.15(ve)-.25 G(rs e).15 E
(xplicitly respond to)-.15 E F1(NORM_CMD)2.5 E F0
(\(CC\) messages in the form of a)A F1(NORM_ACK)2.5 E F0(\(R)A
(TT\) message.)-.6 E(Recei)5 E -.15(ve)-.25 G(rs that are).15 E
(are mark)54 480 Q(ed as CLR or PLR nodes in the)-.1 E F1(NORM_CMD)2.5 E
F0(\(CC\) "cc_node_list" immeditately pro)A
(vide feedback in the form of a)-.15 E F1(NORM_ACK)54 492 Q F0
(to this message.)2.5 E(When a)5 E F1(NORM_CMD)2.5 E F0(\(CC\) is recei)
A -.15(ve)-.25 G(d, non-CLR or non-PLR nodes initiate random feedback)
.15 E(back)54 504 Q(of)-.1 E 2.5(ft)-.25 G
(imeouts similar to that used when the recei)-2.5 E -.15(ve)-.25 G 2.5
(ri).15 G(nitiates a repair c)-2.5 E
(ycle \(see Section 5.3\) in response to detection of)-.15 E(data loss.)
54 516 Q
(The goal of the congestion control feedback is to determine the recei)5
E -.15(ve)-.25 G(rs with the lo).15 E(west congestion control rates.)
-.25 E(As described in [21], the recei)54 528 Q -.15(ve)-.25 G 2.5(rc)
.15 G(ongestion control feedback \(A)-2.5 E
(CK\) timeouts can be biased in f)-.4 E -.2(avo)-.1 G 2.5(ro).2 G 2.5
(fl)-2.5 G -.25(ow)-2.5 G(er rate recei).25 E -.15(ve)-.25 G(rs).15 E
(\(while maintaining ef)54 540 Q(fecti)-.25 E .3 -.15(ve f)-.25 H
(eedback suppression\).).15 E
(Such biasing is not necessarily possible with suppression of)5 E F1
(NORM_NACK)54 552 Q F0(messages since pre)2.5 E(vious data and repair l\
oss history may not be correlated with the current data loss.)-.25 E
(The back)54 576 Q(of)-.1 E 2.5(ft)-.25 G
(imeout for the congestion control response is pick)-2.5 E
(ed and biased as follo)-.1 E(ws:)-.25 E F1(T_backoff = y*r*\(K*GRTTsen\
der\) + \(1 - y\)*RandomBackoff\(K*GRTTsender, GSIZEsender\))61.2 600 Q
F0(where)54 624 Q("y" is the)54 648 Q(fraction of \(K*GR)5 E
(TT\) used to of)-.6 E(fset the back)-.25 E(of)-.1 E 2.5(fw)-.25 G
(ith respect to the sender')-2.5 E 2.5(sc)-.55 G
(urrent transmission rate.)-2.5 E 2.5(Av)5 G(alue of)-2.75 E
(Adamson, Borman, et al.)36 696 Q(Expires September 2003)110.05 E
([P)118.25 E(age 37])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E 2.5(y=0)54 84 S(.25 is recommended.)-2.5 E("r" is)
54 108 Q(adjusted ratio of the local recei)5 E -.15(ve)-.25 G(r').15 E
2.5(sc)-.55 G(alculated rate to the sender')-2.5 E 2.5(sc)-.55 G
(urrent rate. During steady-state congestion control)-2.5 E
(operation, "r" is determined as:)54 120 Q/F1 10/Courier@0 SF 6(r=\()
139.2 144 S(MAX\(MIN\(\(Rcalc / Rsender\), 0.9\), 0.5\) - 0.5\) / 0.4)-6
E F0(During the "slo)54 168 Q 2.5(ws)-.25 G(tart" phase of congestion c\
ontrol operation, "r" is determined simply as:)-2.5 E F1 6(r=R)247.2 192
S(recv / Rsender)-6 E F0(where "Rrecv" is the measured recei)54 216 Q
-.15(ve)-.25 G 2.5(dr).15 G 2.5(ate. The)-2.5 F(recei)2.5 E -.15(ve)-.25
G 2.5(rp).15 G(laces a v)-2.5 E(alue equal to tw)-.25 E 2.5(ot)-.1 G
(imes this "Rrecv" rate in the)-2.5 E("cc_rate" \214eld of its)54 228 Q
F1(NORM_NACK)2.5 E F0(or)2.5 E F1(NORM_ACK)2.5 E F0
(feedback messages during the "slo)2.5 E 2.5(ws)-.25 G
(tart" phase of congestion control)-2.5 E 2.5(operation. If)54 240 R
(the sender chooses this rate as its congestion control rate, this pre)
2.5 E -.15(ve)-.25 G(nts the sender from o).15 E -.15(ve)-.15 G
(rshooting an).15 E(appropriate rate by more than a f)54 252 Q
(actor of tw)-.1 E 2.5(od)-.1 G(uring this "slo)-2.5 E 2.5(ws)-.25 G
(tart" period when recei)-2.5 E -.15(ve)-.25 G(rs ha).15 E .3 -.15
(ve ex)-.2 H(perienced no loss.).15 E(The)54 276 Q F1(RandomBackoff\(\))
2.5 E F0(algorithm pro)2.5 E(vides a truncated e)-.15 E
(xponentially distrib)-.15 E(uted random number and is described in the)
-.2 E(NORM Building Block document [11].)54 288 Q(The same back)5 E(of)
-.1 E 2.5(ff)-.25 G(actor "K" used with the GR)-2.6 E(TT as for)-.6 E F1
(NORM_NACK)2.5 E F0(suppression.)2.5 E(As pre)54 300 Q
(viously noted, a v)-.25 E(alue of)-.25 E F1 6(K=4)2.5 G F0
(is generally recommended for ASM operation and)-3.5 E F1 6(K=6)2.5 G F0
(for SSM operation.)-3.5 E(A)5 E(recei)54 312 Q -.15(ve)-.25 G 2.5(rS)
.15 G(HALL cancel the back)-2.5 E(of)-.1 E 2.5(ft)-.25 G
(imeout and thus its pending transmission of a)-2.5 E F1(NORM_ACK)2.5 E
F0(\(R)A(TT\) message under the)-.6 E(follo)54 324 Q(wing conditions:)
-.25 E(1\))54 354 Q(The recei)67.33 354 Q -.15(ve)-.25 G 2.5(rp).15 G
(ro)-2.5 E(vides another feedback message \()-.15 E F1(NORM_NACK)A F0
(or)2.5 E F1(NORM_ACK)2.5 E F0 2.5(\)b)C(efore the congestion)-2.5 E
(control feedback timeout e)67.33 366 Q(xpires,)-.15 E(2\))54 390 Q 2.5
(A")67.33 390 S(suppressing")-2.5 E F1(NORM_ACK)2.5 E F0(\(R)A
(TT\) message is heard from another recei)-.6 E -.15(ve)-.25 G 2.5(ro)
.15 G 2.5(rv)-2.5 G(ia a)-2.5 E F1(NORM_CMD)67.33 402 Q F0(\(REP)A
(AIR_AD)-.92 E(V\) message from the sender)-.4 E 5(.T)-.55 G
(he local recei)-5 E -.15(ve)-.25 G(r').15 E 2.5(sf)-.55 G
(eedback is canceled if the rate)-2.5 E
(of the competing feedback \(Rfb\) is suf)67.33 414 Q
(\214ciently close to or less than the local recei)-.25 E -.15(ve)-.25 G
(r').15 E 2.5(sc)-.55 G(alculated rate)-2.5 E 2.5(\(Rcalc\). The)67.33
426 R(local recei)2.5 E -.15(ve)-.25 G(r').15 E 2.5(sf)-.55 G
(eedback is canceled when:)-2.5 E F1(Rcalc > \(0.9 * Rfb\))226.33 450 Q
F0(According to [21], this bias of suppression is recommended to help e\
nsure that the recei)54 480 Q -.15(ve)-.25 G 2.5(rw).15 G(ith the lo)
-2.5 E(west rate reports,)-.25 E(while still maintaining a lo)54 492 Q
2.5(wv)-.25 G(olume of feedback from the recei)-2.7 E -.15(ve)-.25 G 2.5
(rs).15 G(et.)-2.5 E(When the back)54 516 Q(of)-.1 E 2.5(ft)-.25 G
(imer e)-2.5 E(xpires, the recei)-.15 E -.15(ve)-.25 G 2.5(rg).15 G
(enerates a)-2.5 E F1(NORM_ACK)2.5 E F0(\(R)A(TT\) message to pro)-.6 E
(vide feedback to the sender and)-.15 E 2.5(group. This)54 528 R
(message may be multicast to the group for most ef)2.5 E(fecti)-.25 E .3
-.15(ve s)-.25 H(uppression in ASM topologies or unicast to the).15 E
(sender depending upon ho)54 540 Q 2.5(wt)-.25 G
(he NORM protocol is deplo)-2.5 E(yed and con\214gured.)-.1 E
(In the congestion control feedback \214elds of)5 E(an)54 552 Q(y)-.15 E
F1(NORM_ACK)2.5 E F0(or)2.5 E F1(NORM_NACK)2.5 E F0(messages, recei)2.5
E -.15(ve)-.25 G(rs will include an adjusted v).15 E
(ersion of the sender timestamp from the most)-.15 E(recently recei)54
564 Q -.15(ve)-.25 G(d).15 E F1(NORM_CMD)2.5 E F0
(\(CC\) message and the greatest "cc_sequence" recei)A -.15(ve)-.25 G
2.5(d. The).15 F(recei)2.5 E -.15(ve)-.25 G 2.5(rS).15 G
(HALL also set an)-2.5 E(y)-.15 E(applicable "cc_\215ags", its current \
"cc_rate", and its "cc_rtt" if kno)54 576 Q 2.5(wn. The)-.25 F
(sender can use the recei)2.5 E -.15(ve)-.25 G -.2(r-).15 G(pro).2 E
(vided pre)-.15 E(vious)-.25 E("cc_rtt" v)54 588 Q(alue to smooth its R)
-.25 E(TT estimate when it is v)-.6 E 2.5(alid. As)-.25 F
(noted in [18], a smoothing constant of 0.5 is recommended for)2.5 E(re)
54 600 Q(gular recei)-.15 E -.15(ve)-.25 G
(rs and 0.9 for CLR \(and PLR\) recei).15 E -.15(ve)-.25 G
(rs from which more rapid feedback is recei).15 E -.15(ve)-.25 G(d.).15
E(During "slo)54 624 Q 2.5(ws)-.25 G(tart" \(when the recei)-2.5 E -.15
(ve)-.25 G 2.5(rh).15 G
(as not yet detected loss from the sender\), the recei)-2.5 E -.15(ve)
-.25 G 2.5(ru).15 G(ses a v)-2.5 E(alue equal to tw)-.25 E 2.5(ot)-.1 G
(imes)-2.5 E
(its measured rate from the sender in the "cc_rate" \214eld.)54 636 Q
-.15(Fo)5 G 2.5(rs).15 G
(teady-state congestion control operation, the recei)-2.5 E -.15(ve)-.25
G 2.5(r").15 G(cc_rate")-2.5 E -.25(va)54 648 S
(lue is based on the equation based v).25 E
(alue using its current loss e)-.25 E -.15(ve)-.25 G
(nt estimate and sender<->recei).15 E -.15(ve)-.25 G 2.5(rR).15 G
(TT information.)-3.1 E(Adamson, Borman, et al.)36 696 Q
(Expires September 2003)110.05 E([P)118.25 E(age 38])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(After a congestion control feedback message is ge\
nerated or when the feedback is suppressed, the recei)54 84 Q -.15(ve)
-.25 G 2.5(rb).15 G -.15(eg)-2.5 G(ins a).15 E("holdof)54 96 Q(f" timeo\
ut period during which it will restrain itself from initiating another \
feedback c)-.25 E(ycle, e)-.15 E -.15(ve)-.25 G 2.5(ni).15 G(f)-2.5 E/F1
10/Courier@0 SF(NORM_CMD)2.5 E F0(\(CC\))A(messages are recei)54 108 Q
-.15(ve)-.25 G 2.5(df).15 G(rom the sender \(unless the recei)-2.5 E .3
-.15(ve b)-.25 H(ecomes mark).15 E(ed as a CLR or PLR node\).)-.1 E
(The v)5 E(alue of this)-.25 E(holdof)54 120 Q 2.5(ft)-.25 G
(imeout period is:)-2.5 E F1(T_holdoff = \(K*GRTT\))244.2 144 Q F0
(Thus, non-CLR recei)54 168 Q -.15(ve)-.25 G(rs are constrained to pro)
.15 E(viding e)-.15 E(xplicit congestion control feedback once per)-.15
E F1(K*GRTT)2.5 E F0(interv)2.5 E(als.)-.25 E(Note, ho)54 180 Q(we)-.25
E -.15(ve)-.25 G .8 -.4(r, t).15 H(hat as the session progresses, dif).4
E(ferent recei)-.25 E -.15(ve)-.25 G(rs will be responding to dif).15 E
(ferent)-.25 E F1(NORM_CMD)2.5 E F0(\(CC\) messages)A
(and there will be relati)54 192 Q -.15(ve)-.25 G(ly continuous feedbac\
k of congestion control information while the sender is acti).15 E -.15
(ve)-.25 G(.).15 E/F2 10/Times-BoldItalic@0 SF 2.5(5.5.2.3 Congestion)54
216 R(Control Rate Adjustment)2.5 E F0(During steady-state operation, t\
he sender will directly adjust its transmission rate to the rate indica\
ted by the feedback from)54 240 Q
(its currently selected CLR according to an)54 252 Q 2.5(yl)-.15 G
(imitations described in [18].)-2.5 E
(As noted there, the estimation of parameters \(loss)5 E(and R)54 264 Q
(TT\) for the CLR will generally constrain the rate changes possible wi\
thin acceptable bounds.)-.6 E -.15(Fo)5 G 2.5(rr).15 G
(ate increases, the)-2.5 E(sender SHALL observ)54 276 Q 2.5(eam)-.15 G
(aximum rate of increase of one pack)-2.5 E(et per R)-.1 E
(TT at all times during steady-state operation.)-.6 E(Note)5 E
(that the sender SHALL maintain a smoothed R)54 288 Q
(TT estimate for the CLR upon ne)-.6 E 2.5(wf)-.25 G
(eedback from the CLR where:)-2.5 E F1
(RTT_clr = 0.9 * RTT_clr + 0.1 * RTT_clrNew)178.2 312 Q F0(")54 336 Q F1
(RTT_clrNew)A F0 2.5("i)C 2.5(st)-2.5 G(he ne)-2.5 E 2.5(wR)-.25 G
(TT calculated from the timestamp in the feedback message recei)-3.1 E
-.15(ve)-.25 G 2.5(df).15 G(rom the CLR.)-2.5 E(The)5 E F1(RTTclr)54 348
Q F0(is initialized to)2.5 E F1(RTT_clrNew)2.5 E F0
(on the \214rst feedback message recei)2.5 E -.15(ve)-.25 G 2.5(d. Note)
.15 F(that the same procedure is observ)2.5 E(ed)-.15 E
(by the sender for PLR recei)54 360 Q -.15(ve)-.25 G(rs and that if a P\
LR is "promoted" to PLR status, the smoothed estimate can be continued.)
.15 E(There are some additional periods besides steady-state operation \
which need to be considered in this protocol operation.)54 384 Q
(These periods aare:)54 396 Q 25.17(1\) during)90 420 R
(session startup,)2.5 E 25.17(2\) when)90 432 R(no feedback is recei)2.5
E -.15(ve)-.25 G 2.5(df).15 G(rom the CLR, and)-2.5 E 25.17(3\) when)90
444 R(the sender has a break in data transmission.)2.5 E
(During session startup, the congestion control operation SHALL observ)
72 468 Q 2.5(ea")-.15 G(slo)-2.5 E 2.5(ws)-.25 G
(tart" procedure to quickly approach)-2.5 E(its f)72 480 Q
(air bandwidth share.)-.1 E
(An initial sender startup rate is assumed where:)5 E F1(Rinitial = MIN\
\(NormSegmentSize / GRTT, NormSegmentSize\) bytes/second.)106.2 504 Q F0
(The rate is increased only when feedback is recei)72 528 Q -.15(ve)-.25
G 2.5(df).15 G(rom the recei)-2.5 E -.15(ve)-.25 G 2.5(rs).15 G 2.5
(et. The)-2.5 F("slo)2.5 E 2.5(ws)-.25 G(tart" phase proceeds until an)
-2.5 E(y)-.15 E(recei)72 540 Q -.15(ve)-.25 G 2.5(rp).15 G(ro)-2.5 E
(vides feedback indicating that loss has occurred.)-.15 E
(Rate increase during "slo)5 E 2.5(ws)-.25 G(tart" is applied as:)-2.5 E
F1(Rnew = Rrecv_min)265.2 564 Q F0
(where "Rrecv_min" is the minimum reported recei)72 588 Q -.15(ve)-.25 G
2.5(rr).15 G
(ate in the "cc_rate" \214eld of congestion control feedback)-2.5 E
(messages recei)72 600 Q -.15(ve)-.25 G 2.5(df).15 G(rom the group.)-2.5
E(Note that during "slo)5 E 2.5(ws)-.25 G(tart", recei)-2.5 E -.15(ve)
-.25 G(rs use tw).15 E 2.5(ot)-.1 G(imes their measured rate from the)
-2.5 E(sender in the "cc_rate" \214eld of their feedback.)72 612 Q
(Rate increase adjustment is limited to once per GR)5 E(TT during slo)
-.6 E 2.5(ws)-.25 G(tart.)-2.5 E(If the CLR or an)72 636 Q 2.5(yr)-.15 G
(ecei)-2.5 E -.15(ve)-.25 G 2.5(ri).15 G(ntends to lea)-2.5 E .3 -.15
(ve t)-.2 H(he group, it will set the NORM_CC_FLA).15 E(G_LEA)-.4 E
(VE in its congestion)-1.35 E(control feedback message as an indication\
 that the sender should not select it as the CLR.)72 648 Q
(When the CLR changes to a)5 E(Adamson, Borman, et al.)36 696 Q
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(lo)72 84 Q(wer rate recei)-.25 E -.15(ve)-.25 G .8
-.4(r, t).15 H(he sender should immediately adjust to the ne).4 E 2.5
(wl)-.25 G -.25(ow)-2.5 G(er rate.).25 E
(The sender is limited to increasing its)5 E
(rate at one additional pack)72 96 Q(et per R)-.1 E(TT to)-.6 E -.1(wa)
-.25 G(rds a ne).1 E 1.3 -.65(w, h)-.25 H(igher CLR rate.).65 E
(The sender should also track the "age" of the feedback it has recei)72
120 Q -.15(ve)-.25 G 2.5(df).15 G(rom the CLR by comparing its current)
-2.5 E("cc_sequence" v)72 132 Q
(alue \(Ssender\) to the last "cc_sequence" v)-.25 E(alue recei)-.25 E
-.15(ve)-.25 G 2.5(df).15 G(rom the CLR \(Sclr\).)-2.5 E
(As the "age" of the CLR)5 E(feedback increases with no ne)72 144 Q 2.5
(wf)-.25 G(eedback, the sender SHALL be)-2.5 E
(gin reducing its rate once per CLR R)-.15 E(TT as a congestion)-.6 E
-.2(avo)72 156 S(idance measure.).2 E(The follo)72 180 Q(wing algorithm\
 is used to determine the decrease in sender rate \(Rsender bytes/sec\)\
 as the CLR feedback,)-.25 E(une)72 192 Q(xpectedly)-.15 E 2.5(,e)-.65 G
(xcessi)-2.65 E -.15(ve)-.25 G(ly ages:).15 E/F1 10/Courier@0 SF
(Age = Ssender - Sclr;)72 216 Q
(rate1 = MAX\(\(Rsender - NormSegmentSize\), 0.0\);)72 228 Q
(// bytes per sec)12 E(rate2 = Rsender * 0.5)72 240 Q(if \(Age > 4\))72
252 Q(Rsender = MIN\(rate1, rate2\);)108 264 Q(else if \(Age > 2\))72
276 Q(Rsender = MAX\(rate1, rate2\);)108 288 Q F0
(This rate reduction occurs limited to the lo)72 312 Q
(wer bound on NORM transmission rate.)-.25 E(After)5 E F1
(NORM_ROBUST_FACTOR)2.5 E F0(consecuti)72 324 Q -.15(ve)-.25 G F1
(NORM_CMD)2.65 E F0(\(CC\) rounds without an)A 2.5(yf)-.15 G
(eedback from the CLR, the sender SHOULD assume the CLR has)-2.5 E
(left the group and pick the recei)72 336 Q -.15(ve)-.25 G 2.5(rw).15 G
(ith the ne)-2.5 E(xt lo)-.15 E(west rate as the ne)-.25 E 2.5(wC)-.25 G
2.5(LR. Note)-2.5 F(this assumes that the sender does)2.5 E(not ha)72
348 Q .3 -.15(ve ex)-.2 H(plicit kno).15 E
(wledge that the CLR intentionally left the group.)-.25 E
(After such a CLR timeout, the sender will be)5 E
(transmitting with a minimal rate and should return to slo)72 360 Q 2.5
(ws)-.25 G(tart as described here for a break in data transmission.)-2.5
E(When the sender has a break in its data transmission, it can continue\
 to probe the group with)72 384 Q F1(NORM_CMD)2.5 E F0(\(CC\) messages)A
(to maintain R)72 396 Q(TT collection from the group.)-.6 E(This will e\
nable the sender to quickly determine an appropriate CLR upon)5 E
(data transmission restart.)72 408 Q(Ho)5 E(we)-.25 E -.15(ve)-.25 G .8
-.4(r, t).15 H(he sender should e).4 E(xponentially reduce its tar)-.15
E(get rate to be used for transmission)-.18 E
(restart as time since the break elapses.)72 420 Q(The tar)5 E
(get rate SHOULD be recalculated once per CLR R)-.18 E(TT as:)-.6 E F1
(Rsender = Rsender * 0.5;)241.2 444 Q F0
(Upon restart, the sender should set the NORM_FLA)72 468 Q(G_ST)-.4 E
(AR)-.93 E 2.5<548d>-.6 G(ag in its)-2.5 E F1(NORM_CMD)2.5 E F0
(\(CC\) messages and the group)A(should observ)72 480 Q(er "slo)-.15 E
2.5(ws)-.25 G(tart" congestion control procedures until an)-2.5 E 2.5
(yr)-.15 G(ecei)-2.5 E -.15(ve)-.25 G 2.5(re).15 G(xperiences a ne)-2.65
E 2.5(wl)-.25 G(oss e)-2.5 E -.15(ve)-.25 G(nt.).15 E/F2 10
/Times-BoldItalic@0 SF(5.5.3 NORM P)72 504 Q(ositiv)-.55 E 2.5(eA)-.15 G
-.1(ck)-2.5 G(no).1 E(wledgment Procedure)-.25 E F0(NORM pro)72 528 Q
(vides an option for the source application to request positi)-.15 E .3
-.15(ve a)-.25 H(ckno).15 E(wledgment \(A)-.25 E(CK\) of)-.4 E F1
(NORM_CMD)72 540 Q F0(\(A)A
(CK_REQ\) messages from members of the group.)-.4 E(There are a fe)5 E
2.5(wt)-.25 G(ypes of speci\214c ackno)-2.5 E(wledgement)-.25 E
(requests that are de\214ned for the NORM protocol and a range of ackno)
72 552 Q(wledgment request types which left to be de\214ned)-.25 E
(by the application.)72 564 Q(One prede\214ned ackno)5 E
(wledgement type is the)-.25 E F1(NORM_ACK)2.5 E F0(\(W)A -1.11(AT)-1.2
G(ERMARK\) that is used to determine)1.11 E(if recei)72 576 Q -.15(ve)
-.25 G(rs ha).15 E .3 -.15(ve a)-.2 H(chei).15 E -.15(ve)-.25 G 2.5(dc)
.15 G(ompletion of reliable reception up through an identi\214ed transm\
ission point with respect to)-2.5 E(the sender')72 588 Q 2.5(sl)-.55 G
(ogical sequence of transmission.)-2.5 E(The)5 E F1(NORM_ACK)2.5 E F0
(\(W)A -1.11(AT)-1.2 G(ERMARK\) ackno)1.11 E(wledgement may be used to)
-.25 E(assist in application \215o)72 600 Q 2.5(wc)-.25 G
(ontrol when the sender has information on a portion of the recei)-2.5 E
-.15(ve)-.25 G 2.5(rs).15 G 2.5(et. Another)-2.5 F(prede\214ned)2.5 E
(ackno)72 612 Q(wledgement type is)-.25 E F1(NORM_ACK)2.5 E F0
(\(CC\), which is used to e)A(xplicitly pro)-.15 E
(vide congestion control feedback in response)-.15 E(to)72 624 Q F1
(NORM_CMD)2.5 E F0(\(CC\) messages transmitted by the sender)A 5(.N)-.55
G(ote the)-5 E F1(NORM_ACK)2.5 E F0(\(CC\) response does NO)A 2.5(Tf)-.4
G(ollo)-2.5 E 2.5(wt)-.25 G(he)-2.5 E(positi)72 636 Q .3 -.15(ve a)-.25
H(ckno).15 E(wledgement procedure described here.)-.25 E(The)5 E F1
(NORM_CMD)2.5 E F0(\(A)A(CK_REQ\) and)-.4 E F1(NORM_ACK)2.5 E F0
(messages contain)2.5 E
(an "ack_type" \214eld to identify the type of ackno)72 648 Q
(wledgement requested and pro)-.25 E 2.5(vided. A)-.15 F
(range of "ack_type" v)2.5 E(alues is)-.25 E(Adamson, Borman, et al.)36
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(pro)72 84 Q(vided for application-de\214ned use.)
-.15 E(While the application initiates the ackno)5 E
(wledgement request and interprets)-.25 E
(application-de\214ned "ack_type" v)72 96 Q(alues, the ackno)-.25 E
(wledgment request and response is conducted with the follo)-.25 E(wing)
-.25 E(procedure.)72 108 Q(The NORM positi)72 132 Q .3 -.15(ve a)-.25 H
(ckno).15 E
(wledgement procedure uses polling by the sender to query the recei)-.25
E -.15(ve)-.25 G 2.5(rg).15 G(roup for response.)-2.5 E
(Note this polling procedure is not intended to scale to v)72 144 Q
(ery lar)-.15 E(ge recei)-.18 E -.15(ve)-.25 G 2.5(rg).15 G(roups, b)
-2.5 E(ut could be used in lar)-.2 E(ge group)-.18 E
(setting to query a critical subset of the group.)72 156 Q(The)5 E/F1 10
/Courier@0 SF(NORM_CMD)2.5 E F0(\(A)A
(CK_REQ\) message is used for polling and contains a)-.4 E
(list of NormNodeIds for recei)72 168 Q -.15(ve)-.25 G
(rs that should respond to the command.).15 E(The list of recei)5 E -.15
(ve)-.25 G(rs pro).15 E(viding)-.15 E(ackno)72 180 Q
(wledgement is determined by the source application with "a priori" kno)
-.25 E(wledge of participating nodes or via some)-.25 E
(other application-le)72 192 Q -.15(ve)-.25 G 2.5(lm).15 G(echanism.)
-2.5 E(The A)72 216 Q
(CK process is initiated by the sender who generates)-.4 E F1(NORM_CMD)
2.5 E F0(\(A)A(CK_REQ\) messages in periodic "rounds".)-.4 E -.15(Fo)5 G
(r).15 E F1(NORM_ACK)72 228 Q F0(\(W)A -1.11(AT)-1.2 G(ERMARK\), these \
requests contain the "object_transport_id", "fec_block_number", and)1.11
E("fec_symbol_id" denoting the w)72 240 Q(atermark transmission point.)
-.1 E -.15(Fo)5 G 2.5(ra).15 G
(pplication-de\214ned requests, the "ack_req_content")-2.5 E
(\214eld of the)72 252 Q F1(NORM_CMD)2.5 E F0(\(A)A
(CK_REQ\) is set and interpreted by the sender and recei)-.4 E -.15(ve)
-.25 G 2.5(ra).15 G(pplications, respecti)-2.5 E -.15(ve)-.25 G(ly).15 E
5(.I)-.65 G(n)-5 E(response to the)72 264 Q F1(NORM_CMD)2.5 E F0(\(A)A
(CK_REQ\), the listed recei)-.4 E -.15(ve)-.25 G(rs randomly spread).15
E F1(NORM_ACK)2.5 E F0(messages uniformly in time)2.5 E -.15(ove)72 276
S 2.5(raw).15 G(indo)-2.5 E 2.5(wo)-.25 G 2.5(f\()-2.5 G(1*GR)-2.5 E 2.5
(TT\). These)-.6 F F1(NORM_ACK)2.5 E F0
(messages are typically unicast to the sender)2.5 E(.)-.55 E(The A)72
300 Q(CK process is self-limiting and a)-.4 E -.2(vo)-.2 G(ids A).2 E
(CK implosion in that:)-.4 E 25.17(1\) Only)90 324 R 2.5(as)2.5 G(ingle)
-2.5 E F1(NORM_CMD)2.5 E F0(\(A)A
(CK_REQ\) message is generated once per \(2*GR)-.4 E(TT\), and)-.6 E
25.17(2\) The)90 348 R
(size of the "acking_node_list" of NormNodeIds from which A)2.5 E
(CK is requested is limited to a)-.4 E(maximum of the sender NormSe)126
360 Q(gmentSize setting per round of the positi)-.15 E .3 -.15(ve a)-.25
H(ckno).15 E(wledgement process.)-.25 E
(Because the size of the included list is limited to the sender')72 384
Q 2.5(sN)-.55 G(ormSe)-2.5 E(gmentSize setting, multiple)-.15 E F1
(NORM_CMD)72 396 Q F0(\(A)A(CK_REQ\) rounds may be required to achie)-.4
E .3 -.15(ve r)-.25 H(esponses from all recei).15 E -.15(ve)-.25 G
(rs speci\214ed.).15 E(The content of the)7.5 E(attached NormNodeId lis\
t will be dynamically updated as this process progresses and A)72 408 Q
(CKs are recei)-.4 E -.15(ve)-.25 G 2.5(df).15 G(rom the)-2.5 E
(speci\214ed recei)72 420 Q -.15(ve)-.25 G 2.5(rs).15 G 2.5(et. Thus,)
-2.5 F(as the sender recei)2.5 E -.15(ve)-.25 G 2.5(sr).15 G
(esponses from recei)-2.5 E -.15(ve)-.25 G
(rs, it eliminates them from the subsequent).15 E F1(NORM_CMD)72 432 Q
F0(\(A)A(CK_REQ\) message payload list and adds in an)-.4 E 2.5(yp)-.15
G(ending recei)-2.5 E -.15(ve)-.25 G 2.5(rN).15 G(ormNodeIds k)-2.5 E
(eeping within the)-.1 E(NormSe)72 444 Q
(gmentSize limitation of the list size.)-.15 E(Each recei)5 E -.15(ve)
-.25 G 2.5(ri).15 G 5(sq)-2.5 G(ueried a maximum number of times)-5 E
(\()72 456 Q F1(NORM_ROBUST_FACTOR)A F0 2.5(,b)C 2.5(yd)-2.5 G(ef)-2.5 E
2.5(ault\). Recei)-.1 F -.15(ve)-.25 G
(rs not responding within this number of repeated requests are remo).15
E -.15(ve)-.15 G(d).15 E(from the payload list to mak)72 468 Q 2.5(ep)
-.1 G(otential room for other recei)-2.5 E -.15(ve)-.25 G
(rs pending ackno).15 E 2.5(wledgement. The)-.25 F(transmission of the)
2.5 E F1(NORM_CMD)72 480 Q F0(\(A)A(CK_REQ\) is repeated until no furth\
er responses are required or until the repeat threshold is e)-.4 E
(xceeded for)-.15 E(all pending recei)72 492 Q -.15(ve)-.25 G 2.5
(rs. The).15 F(transmission of)2.5 E F1(NORM_CMD)2.5 E F0(\(A)A
(CK_REQ\) messages to conduct the positi)-.4 E .3 -.15(ve a)-.25 H(ckno)
.15 E(wledgment)-.25 E(process is multiple)72 504 Q -.15(xe)-.15 G 2.5
(dw).15 G(ith ongoing sender data transmissions.)-2.5 E(Ho)5 E(we)-.25 E
-.15(ve)-.25 G .8 -.4(r, t).15 H(he positi).4 E .3 -.15(ve a)-.25 H
(ckno).15 E(wledgment process may be)-.25 E
(interrupted in response to ne)72 516 Q -.05(ga)-.15 G(ti).05 E .3 -.15
(ve a)-.25 H(ckno).15 E(wledgement repair requests \(N)-.25 E -.4(AC)
-.35 G(Ks\) recei).4 E -.15(ve)-.25 G 2.5(df).15 G(rom recei)-2.5 E -.15
(ve)-.25 G(rs during the).15 E(ackno)72 528 Q(wledgment period.)-.25 E
(The A)5 E(CK process is resumed once an)-.4 E 2.5(yp)-.15 G
(ending repairs ha)-2.5 E .3 -.15(ve b)-.2 H(een transmitted.).15 E
(In the case of)72 552 Q F1(NORM_CMD)2.5 E F0(\(A)A(CK_REQ\(W)-.4 E
-1.11(AT)-1.2 G(ERMARK\)\) commands, recei)1.11 E -.15(ve)-.25 G
(rs will not A).15 E(CK until the)-.4 E 2.5(yh)-.15 G -2.25 -.2(av e)
-2.5 H(recei)2.7 E -.15(ve)-.25 G(d).15 E
(complete transmission of all data up to and including the w)72 564 Q
(atermark transmission point.)-.1 E(All recei)5 E -.15(ve)-.25 G
(rs SHALL interpret).15 E(the w)72 576 Q(atermark point pro)-.1 E
(vided in the request in the same manner as the transmission point gi)
-.15 E -.15(ve)-.25 G 2.5(ni).15 G(n)-2.5 E F1(NORM_CMD)2.5 E F0
(\(FLUSH\))A(messages and N)72 588 Q -.4(AC)-.35 G 2.5(Kf).4 G
(or repairs if needed.)-2.5 E/F2 10/Times-BoldItalic@0 SF
(5.5.4 Group Size Estimation)72 612 Q F0(NORM sender messages contain a\
 "gsize" \214eld that is a representation of the group size and is used\
 in scaling random)72 636 Q(back)72 648 Q(of)-.1 E 2.5(ft)-.25 G
(imer ranges.)-2.5 E(The use of the group size estimate within the NORM\
 protocol does not require a precise)5 E(Adamson, Borman, et al.)36 696
Q(Expires September 2003)110.05 E([P)118.25 E(age 41])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(estimation and w)72 84 Q(orks reasonably well if \
the estimate is within an order of magnitude of the actual group size.)
-.1 E(By)5 E(def)72 96 Q
(ault, the NORM sender group size estimate may be administrati)-.1 E
-.15(ve)-.25 G(ly con\214gured.).15 E(Also gi)5 E -.15(ve)-.25 G 2.5(nt)
.15 G(he e)-2.5 E(xpected scalability)-.15 E
(of the NORM protocol for general use, a def)72 108 Q(ault v)-.1 E
(alue of 10,000 is recommended for use as the group size estimate.)-.25
E(It is possible that group size may be algorithmically approximated fr\
om the v)72 132 Q(olume of congestion control feedback)-.2 E
(messages which follo)72 144 Q 2.5(wt)-.25 G(he e)-2.5 E
(xponentially weighted random back)-.15 E(of)-.1 E 2.5(f. Ho)-.25 F(we)
-.25 E -.15(ve)-.25 G .8 -.4(r, t).15 H
(he speci\214cation of such an algorithm is).4 E(currently be)72 156 Q
(yond the scope of this document.)-.15 E/F1 10/Times-BoldItalic@0 SF
(5.5.5 Operation with Generic Router Assist \(GRA\))72 180 Q F0
(NORM pack)72 204 Q(et formats will be e)-.1 E(xtended to allo)-.15 E
2.5(wf)-.25 G(or operation with GRA reliable multicast functions.)-2.5 E
(Additional)5 E -.35(NA)72 216 S(CK suppression and selecti)-.05 E .3
-.15(ve s)-.25 H(ub-casting of repair transmissions in the netw).15 E
(ork will be possible with GRA.)-.1 E
(\(Section 5.4.2 discusses some NORM mechanisms related to this\).)72
228 Q(Additional details will be pro)5 E(vide in future v)-.15 E
(ersions)-.15 E(of this document as GRA speci\214cations mature.)72 240
Q/F2 10/Times-Bold@0 SF(6.0 Security Considerations)36 264 Q F0(The sam\
e security considerations that apply to the NORM, FEC, and TFMCC)72 288
Q -.2(bu)5 G(ilding blocks also apply to the NORM).2 E 2.5(protocol. In)
72 300 R(addition to vulnerabilities that an)2.5 E 2.5(yI)-.15 G 2.5(Pa)
-2.5 G(nd IP multicast protocol implementation may be generally subject)
-2.5 E(to, the N)72 312 Q -.4(AC)-.35 G 2.5(Kb).4 G
(ased feedback of NORM may be e)-2.5 E
(xploited by replay attacks which force the NORM sender to)-.15 E
(unnecessarily transmit repair information.)72 324 Q(This MA)5 E 2.5(Yb)
-1.05 G 2.5(ea)-2.5 G(ddressed by netw)-2.5 E
(ork layer IP security implementations that)-.1 E(guard ag)72 336 Q
(ainst this potential security e)-.05 E 2.5(xploitation. It)-.15 F
(is RECOMMENDED that such IP security mechanisms be used)2.5 E(when a)72
348 Q -.25(va)-.2 G 2.5(ilable. Another).25 F(possible approach is for \
NORM senders to use the "sequence" \214eld from the NORM Common)2.5 E
(Message Header to detect replay attacks.)72 360 Q
(This can be accomplished if the sender is willing to maintain state on)
5 E(recei)72 372 Q -.15(ve)-.25 G(rs which are N).15 E -.4(AC)-.35 G 2.5
(King. A).4 F(cache of recei)2.5 E -.15(ve)-.25 G 2.5(rs).15 G
(tate may pro)-2.5 E(vide some protection ag)-.15 E
(ainst replay attacks.)-.05 E(Note that)5 E(the "sequence" \214eld shou\
ld be incremented by NormNodes with independent v)72 384 Q
(alues for "sender" messages v)-.25 E(ersus)-.15 E("recei)72 396 Q -.15
(ve)-.25 G(r" messages so that the congestion control loss estimation f\
unction of the "sequence" \214eld can be preserv).15 E(ed for)-.15 E
(sender messages when recei)72 408 Q -.15(ve)-.25 G 2.5(rm).15 G
(essages are unicast to the sender)-2.5 E(.)-.55 E(While NORM does le)72
432 Q -.15(ve)-.25 G(rage FEC-based repair for scalability).15 E 2.5(,t)
-.65 G(his does not alone guarantee inte)-2.5 E(grity of recei)-.15 E
-.15(ve)-.25 G 2.5(dd).15 G(ata.)-2.5 E(Application-le)72 444 Q -.15(ve)
-.25 G 2.5(li).15 G(nte)-2.5 E
(grity-checking of data content is highly RECOMMENDED.)-.15 E(The NORM \
protocol is compatible with the use of the IP security \(IPSEC\) archit\
ecture described in [23].)72 468 Q F2(7.0 Suggested Use)36 492 Q F0
(The present NORM protocol is seen as useful tool for the)72 516 Q
(reliable data transfer o)5 E -.15(ve)-.15 G 2.5(rg).15 G
(eneric IP multicast)-2.5 E 2.5(services. It)5 F(is)2.5 E
(not the intention of the authors to suggest it is suitable for)72 528 Q
(supporting all en)5 E(visioned multicast reliability requirements.)-.4
E(NORM pro)72 540 Q(vides a simple and \215e)-.15 E(xible frame)-.15 E
-.1(wo)-.25 G(rk for multicast applications with a de).1 E
(gree of concern for netw)-.15 E(ork traf)-.1 E<8c63>-.25 E
(implosion and protocol o)72 552 Q -.15(ve)-.15 G(rhead ef).15 E
(\214cienc)-.25 E 3.8 -.65(y. N)-.15 H(ORM-lik).65 E 2.5(ep)-.1 G
(rotocols ha)-2.5 E .3 -.15(ve b)-.2 H
(een successfully demonstrated within the).15 E(MBone for b)72 564 Q(ul\
k data dissemination applications, including weather satellite compress\
ed imagery updates servicing a)-.2 E(lar)72 576 Q(ge group of recei)-.18
E -.15(ve)-.25 G
(rs and a generic web content reliable "push" application.).15 E
(In addition, this frame)72 600 Q -.1(wo)-.25 G
(rk approach has some design features making it attracti).1 E .3 -.15
(ve f)-.25 H(or b).15 E(ulk transfer in asymmetric and)-.2 E
(wireless internetw)72 612 Q(ork applications.)-.1 E
(NORM is capable of successfully operating independent of netw)5 E
(ork structure and in)-.1 E(en)72 624 Q(vironments with high pack)-.4 E
(et loss, delay)-.1 E 2.5(,a)-.65 G(nd misordering.)-2.5 E
(Hybrid proacti)7.5 E -.15(ve)-.25 G(/reacti).15 E .3 -.15(ve F)-.25 H
(EC-based repairing impro).15 E -.15(ve)-.15 G
(protocol performance in some multicast scenarios.)72 636 Q 2.5(As)5 G
(ender)-2.5 E(-only repair approach often mak)-.2 E
(es additional engineering)-.1 E(sense in asymmetric netw)72 648 Q 2.5
(orks. NORM')-.1 F 2.5(su)-.55 G
(nicast feedback capability may be suitable for use in asymmetric netw)
-2.5 E(orks or)-.1 E(Adamson, Borman, et al.)36 696 Q
(Expires September 2003)110.05 E([P)118.25 E(age 42])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E(in netw)72 84 Q
(orks where only unidirectional multicast routing/deli)-.1 E -.15(ve)
-.25 G(ry service e).15 E(xists. Asymmetric architectures supporting)
-.15 E(multicast deli)72 96 Q -.15(ve)-.25 G(ry are lik).15 E
(ely to mak)-.1 E 2.5(eu)-.1 G 2.5(pa)-2.5 G 2.5(ni)-2.5 G(mportant por\
tion of the future Internet structure \(e.g., DBS/cable/PSTN)-2.5 E -.05
(hy)72 108 S(brids\) and ef).05 E(\214cient, reliable b)-.25 E
(ulk data transfer will be an important capability for servicing lar)-.2
E(ge groups of subscribed)-.18 E(recei)72 120 Q -.15(ve)-.25 G(rs.).15 E
/F1 10/Times-Bold@0 SF(8.0 Refer)36 180 Q(ences)-.18 E F0([1])77 210 Q
-.25(Ke)122.398 210 S(rmode, R., V).25 E
(icisano, L., "Author Guidelines for Reliable Multicast T)-.6 E
(ransport \(RMT\) Building Blocks)-.35 E
(and Protocol Instantiation documents", RFC 3269, April 2002.)122.398
222 Q([2])77 246 Q(Bradner)122.398 246 Q 2.5(,S)-.4 G(., "K)-2.5 E .3
-.15(ey w)-.25 H(ords for use in RFCs to Indicate Requirement Le).05 E
-.15(ve)-.25 G(ls", BCP 14, RFC 2119, March).15 E(1997.)122.398 258 Q
([3])77 282 Q(Mankin, A., Romano)122.398 282 Q 1.3 -.65(w, A)-.25 H
(., Bradner).65 E 2.5(,S)-.4 G 2.5(.a)-2.5 G(nd V)-2.5 E 2.5(.P)-1.29 G
(axson, "IETF Criteria for Ev)-2.65 E(aluating Reliable Multicast)-.25 E
-.35(Tr)122.398 294 S
(ansport and Application Protocols", RFC 2357, June 1998.).35 E([4])77
318 Q(Whetten, B., V)122.398 318 Q(icisano, L., K)-.6 E
(ermode, R., Handle)-.25 E 1.3 -.65(y, M)-.15 H(., Flo).65 E
(yd S. and Luby)-.1 E 2.5(,M)-.65 G(., "Reliable Multicast T)-2.5 E
(ransport)-.35 E(Building Blocks for One-to-Man)122.398 330 Q 2.5(yB)
-.15 G(ulk-Data T)-2.5 E(ransfer", RFC 3048, January 2001.)-.35 E([5])77
354 Q(Handle)122.398 354 Q 1.3 -.65(y, M)-.15 H 2.5(.a).65 G(nd V)-2.5 E
2.5(.J)-1.29 G
(acobson, "SDP: Session Description Protocol", RFC 2327, April 1998.)
-2.5 E([6])77 378 Q(Handle)122.398 378 Q 1.3 -.65(y, M)-.15 H(., Perkin\
s, C. and E. Whelan, "Session Announcement Protocol", RFC 2974, October\
 2000.).65 E([7])77 402 Q(S. Ping)122.398 402 Q(ali, D. T)-.05 E -.25
(ow)-.8 G(sle).25 E 1.3 -.65(y, J)-.15 H 2.5(.K).65 G
(urose, "A Comparison of Sender)-2.65 E(-Initiated and Recei)-.2 E -.15
(ve)-.25 G -.2(r-).15 G(Initiated Reliable).2 E(Multicast Protocols", I\
n Proc. INFOCOM, San Francisco CA, October 1993.)122.398 414 Q([8])77
438 Q(Luby)122.398 438 Q 2.5(,M)-.65 G(., V)-2.5 E
(icisano, L., Gemmell, J., Rizzo, L., Handle)-.6 E 1.3 -.65(y, M)-.15 H
2.5(.a).65 G(nd J. Cro)-2.5 E(wcroft, "The Use of F)-.25 E(orw)-.15 E
(ard Error)-.1 E
(Correction \(FEC\) in Reliable Multicast", RFC 3453, December 2002.)
122.398 450 Q([9])77 474 Q(J. Mack)122.398 474 Q(er)-.1 E 2.5(,R)-.4 G
2.5(.A)-2.5 G(damson, "The Multicast Dissemination Protocol \(MDP\) T)
-2.5 E(oolkit", Proc. IEEE MILCOM 99,)-.8 E(October 1999.)122.398 486 Q
([10])72 510 Q(J. Nonnenmacher and E. Biersack, "Optimal Multicast Feed\
back", Proc. IEEE INFOCOMM, p. 964,)122.398 510 Q(March/April 1998.)
122.398 522 Q([11])72 546 Q(J. Mack)122.398 546 Q(er)-.1 E 2.5(,R)-.4 G
2.5(.A)-2.5 G(damson, "Quantitati)-2.5 E .3 -.15(ve P)-.25 H
(rediction of Nack Oriented Reliable Multicast \(NORM\) Feedback",).15 E
(Proc. IEEE MILCOM 2002, October 2002.)122.398 558 Q([12])72 582 Q 1.48
-.74(T. S)122.398 582 T(peakman, L. V).74 E
(icisano, "Reliable Multicast T)-.6 E
(ransport Building Block Generic Roouter Assist -)-.35 E(Signalling Pro\
tocol Speci\214cation", Internet Draft draft-ietf-rmt-bb-gra-signalling\
-01.txt, January 2003,)122.398 594 Q -.1(wo)122.398 606 S
(rk in progress.).1 E(Citation for informational purposes only)5 E(.)
-.65 E([13])72 630 Q(Deering, S., "Host Extensions for IP Multicasting"\
, STD 5, RFC 1112, August 1989.)122.398 630 Q(Adamson, Borman, et al.)36
696 Q(Expires September 2003)110.05 E([P)118.25 E(age 43])-.15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(March 2003)177.405 E([14])72 84 Q(Holbrook, H. W)122.398 84 Q
(., "A Channel Model for Multicast", Ph.D. Dissertation, Stanford Uni)
-.92 E -.15(ve)-.25 G(rsity).15 E 2.5(,D)-.65 G(epartment of)-2.5 E
(Computer Science, Stanford, California, August 2001.)122.398 96 Q([15])
72 120 Q(B. Adamson, C. Bormann, M. Handle)122.398 120 Q 1.3 -.65(y, a)
-.15 H(nd J. Mack).65 E(er)-.1 E 2.5(,")-.4 G -.35(NA)-2.5 G
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122.398 432 Q(ent and R. Atkinson, "Security Architecture for the Inter\
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