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(nsportId).15 E F0(assignments)2.5 E(independently so that indi)54 276 Q
(vidual)-.25 E F2(NormObjects)2.5 E F0(may be uniquely identi\214ed dur\
ing transport with the concatenation of the)2.5 E
(sender session-unique identi\214er \()54 288 Q F2(NormNodeId)A F0 2.5
(\)a)C(nd the assigned)-2.5 E F2(NormT)2.5 E -.15(ra)-.55 G(nsportId).15
E F0 5(.T)C(he)-5 E F2(NormT)2.5 E -.15(ra)-.55 G(nsportId).15 E F0 2.5
(sa)C(re assigned)-2.5 E(from a lar)54 300 Q(ge, b)-.18 E(ut \214x)-.2 E
(ed, numeric space in increasing order and may be reassigned during lon\
g-li)-.15 E -.15(ve)-.25 G 2.5(ds).15 G 2.5(essions. The)-2.5 F(NORM)2.5
E(protocol pro)54 312 Q(vides mechanisms so that the sender application\
 may terminate transmission of data content and inform the)-.15 E
(group of this in an ef)54 324 Q(\214cient manner)-.25 E 5(.O)-.55 G(th\
er similar protocol control mechanisms \(e.g., session termination, rec\
ei)-5 E -.15(ve)-.25 G(r).15 E(synchronization, etc\) are speci\214ed s\
o that reliable multicast application v)54 336 Q
(ariants may construct dif)-.25 E(ferent, complete b)-.25 E(ulk)-.2 E
(transfer communication models to meet their goals.)54 348 Q 1.6 -.8
(To s)54 372 T(ummarize, the NORM protocol pro).8 E
(vides reliable transport of dif)-.15 E
(ferent types of data content \(including potentially mix)-.25 E(ed)-.15
E 2.5(types\). The)54 384 R(senders enqueue and transmit b)2.5 E(ulk co\
ntent in the form of static data or \214les and/or non-\214nite, ongoin\
g stream)-.2 E 2.5(types. NORM)54 396 R(senders pro)2.5 E(vide for repa\
ir transmission of data and/or FEC content in response to N)-.15 E -.4
(AC)-.35 G 2.5(Km).4 G(essages recei)-2.5 E -.15(ve)-.25 G(d).15 E
(from the recei)54 408 Q -.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 speci\214ed)2.5 E(for use by applications to\
 form complete reliable multicast solutions for dif)54 420 Q
(ferent purposes.)-.25 E/F3 10/Times-Bold@0 SF(1.2 NORM Scalability)36
444 Q F0
(Group communication scalability requirements lead to adaptation of ne)
54 468 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].)54 480 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.)54 492 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)54 504 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].)54 516 Q
(The principal f)5 E(actor in NORM scalability is the)-.1 E -.2(vo)54
528 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)54 540 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)
54 552 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')54 564 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)54 576 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
600 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)54 612 Q
(ertises" the feedback state to the group to f)-.15 E
(acilitate feedback suppression.)-.1 E(In typical)5 E(Internet en)54 624
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)
54 636 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(operate with a smaller amount of feedback than a s\
ingle TCP connection, e)54 648 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(Adamson, Bormann, 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
(June 2003)185.175 E(Thus, depending upon the netw)54 84 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 96 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)54 108 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)54 120 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)36 144 Q(vir)-.4 E
(onmental Requir)-.18 E(ements and Considerations)-.18 E F0
(All of the en)54 168 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 [18] also apply\
 to NORM.)54 180 Q(When the RMT Generic)5 E
(Router Assist \(GRA\) Building Block [12] is used with NORM, its en)54
192 Q(vironmental requirements and considerations SHALL)-.4 E
(also apply)54 204 Q(.)-.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
(RA for performance bene\214ts when applicable.)-2.5 E
(While the techniques utilized in NORM)5 E(are principally applicable t\
o "\215at" end-to-end IP multicast multicast topologies, the)54 264 Q
2.5(yc)-.15 G(ould also be applied in the sub-le)-2.5 E -.15(ve)-.25 G
(ls).15 E(of hierarchical \(e.g., tree-based\) multicast distrib)54 276
Q(ution if so desired.)-.2 E(NORM can mak)5 E 2.5(eu)-.1 G
(se of reciprocal \(among senders and)-2.5 E(recei)54 288 Q -.15(ve)-.25
G(rs\) multicast communication under the An).15 E
(y-Source Multicast \(ASM\) model de\214ned in RFC 1112 [13], b)-.15 E
(ut SHALL)-.2 E(also be capable of scalable operation in asymmetric top\
ologies such as Source Speci\214c Multicast \(SSM\) [14] where there)54
300 Q(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)-5 E F2(NormNode)2.5 E F0(within a)2.5 E F2(NormSession)2.5 E
F0(is)2.5 E(assumed to ha)54 444 Q .3 -.15(ve a p)-.2 H
(reselected unique 32-bit identi\214er \().15 E F2(NormNodeId)A F0(\).)A
F2(NormNodes)5 E F0(MUST ha)2.5 E .3 -.15(ve u)-.2 H
(niquely assigned identi\214ers).15 E(within a single)54 456 Q F2
(NormSession)2.5 E F0(to distinquish)2.5 E(between possible multiple se\
nders and to distinguish feedback information from)5 E(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)-.15 E F2(NormNodeId)2.5 E F0 -.25(va)2.5 G
2.5(lues. A).25 F -.25(va)2.5 G(lue of).25 E/F3 10/Courier@0 SF
(0x00000000)2.5 E F0(is considered an in)2.5 E -.25(va)-.4 G(lid).25 E
F2(NormNodeId)54 480 Q F0 -.25(va)2.5 G(lue and a v).25 E(alue of)-.25 E
F3(0xffffffff)2.5 E F0(is a "wildcard")2.5 E F2(NormNodeId)2.5 E F0 5
(.W)C(hile the protocol does not preclude)-5 E
(multiple sender nodes concurrently 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 that ca\
n 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 2.5(,w)C(hich is used for static, persist\
ent blocks 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 2.5(,w)C
(hich 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 ")2.5 E F2(NormObjects)A F0 2.5("o)C 2.5<668c>-2.5
G(nite 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 2.5(,w)C(hich corresponds to an ongoing)-2.5 E
(transmission of unde\214ned length.)54 612 Q
(This is analogous to the reliable stream service pro)5 E
(vide by TCP for unicast data transport.)-.15 E(The format of the strea\
m content is application-de\214ned and may be byte or message oriented.)
54 624 Q(The NORM protocol pro)5 E(vides)-.15 E
(for "\215ushing" of the stream to e)54 636 Q(xpedite deli)-.15 E -.15
(ve)-.25 G(ry or possibly enforce application message boundaries.).15 E
(NORM protocol)5 E(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 out-of-order).15 E(Adamson, Bormann, 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
(June 2003)185.175 E(\(more immediate\) 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, NORM sender and)2.5 E(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/F1
10/Times-Italic@0 SF(NormObjects)2.5 E F0(are)2.5 E(logically se)54 108
Q(gmented into FEC coding blocks and se)-.15 E
(gments for transmission by the sender)-.15 E(.)-.55 E F1(NormObjects)54
132 Q F0(and associated transmission se)2.5 E
(gments are temporarily yet uniquely identi\214ed within the)-.15 E F1
(NormSession)2.5 E F0(conte)2.5 E(xt)-.15 E(using the gi)54 144 Q -.15
(ve)-.25 G 2.5(ns).15 G(ender')-2.5 E(s)-.55 E F1(NormNodeId)2.5 E F0
(and a temporarily unique)2.5 E F1(NormObjectT)2.5 E -.15(ra)-.55 G
(nsportId).15 E F0 5(.T)C(hese data content identi\214ers are)-5 E
(sender)54 156 Q(-assigned and applicable and v)-.2 E
(alid only during a)-.25 E F1(NormObject)2.5 E F0 1.1 -.55('s a)D
(ctual _transport_ \(i.e. for as long as the sender is).55 E
(transmitting and pro)54 168 Q(viding repair of the indicated)-.15 E F1
(NormObject)2.5 E F0 2.5(\). F)B(or a long-li)-.15 E -.15(ve)-.25 G 2.5
(ds).15 G(ession, the)-2.5 E F1(NormObjectT)2.5 E -.15(ra)-.55 G
(nsportId).15 E F0(\214eld)2.5 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)-.25 E F1(NormObject)
2.5 E F0(se)2.5 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/F2 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/F3 10/Courier@0
SF(NORM_DATA)2.5 E F0(that carry the)2.5 E F1(NormObject)2.5 E F0
(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 F3(NORM_INFO)2.5 E F0(is also de\214ned and is used to carry an)2.5 E
2.5(yO)-.15 G(PTION)-2.5 E(AL "out-of-band" conte)-.35 E(xt)-.15 E
(information 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 F3(NORM_INFO)2.5 E F0
(message can be associated with a)2.5 E F1(NormObject)2.5 E F0 5(.B)C
(ecause of)-5 E(its atomic nature, missing)54 396 Q F3(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)-.25 E
(NORM')54 408 Q 2.5(sg)-.55 G(eneral FEC-encoded data content.)-2.5 E F3
(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)-2.5 E(multicast 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)-.15 E(content being transmitted.)54
432 Q(The N)5 E -.4(AC)-.35 G 2.5(Kp).4 G(rocess for)-2.5 E F3
(NORM_INFO)2.5 E F0(will be described later)2.5 E 5(.W)-.55 G(hen the)-5
E F3(NORM_INFO)2.5 E F0(message)2.5 E
(type is used, its transmission should precede transmisson of an)54 444
Q(y)-.15 E F3(NORM_DATA)2.5 E F0(message for the associated)2.5 E F1
(NormObject)2.5 E F0(.)A(The sender also generates messages of type)54
468 Q F3(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)
54 480 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.)54 492 Q
(The transmission of)5 E F3(NORM_CMD)2.5 E F0
(messages from the sender is accomplished by)2.5 E(one of three dif)54
504 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)54 516 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.)54 528 Q(Se)5 E -.15
(ve)-.25 G
(ral core commands are de\214ned for basic protocol operation.).15 E
(Additionally)54 540 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)54 552 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 that can mak)54 564 Q 2.5(eu)-.1 G
(se of information a)-2.5 E -.25(va)-.2 G
(ilable to the underlying NORM protocol engine \(e.g., round-).25 E
(trip timing, transmission rate, etc\).)54 576 Q(NORM recei)54 600 Q
-.15(ve)-.25 G(rs generate messages of type).15 E F3(NORM_NACK)2.5 E F0
(or)2.5 E F3(NORM_ACK)2.5 E F0(in response to transmissions of data and)
2.5 E(commands from a sender)54 612 Q 5(.T)-.55 G(he)-5 E F3(NORM_NACK)
2.5 E F0(messages are generated to request repair of detected data tran\
smission losses.)2.5 E(Recei)54 624 Q -.15(ve)-.25 G(rs generally detec\
t losses by tracking the sequence of transmission from a sender).15 E 5
(.S)-.55 G(equencing information is)-5 E
(embedded in the transmitted data pack)54 636 Q
(ets and end-of-transmission commands from the sender)-.1 E(.)-.55 E F3
(NORM_ACK)5 E F0(messages are)2.5 E
(generated in response to certain commands transmitted by the sender)54
648 Q 5(.I)-.55 G 2.5(nt)-5 G
(he general \(and most scalable\) protocol mode,)-2.5 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Courier@0 SF(NORM_ACK)54 84 Q F0(messages ar\
e sent only in response to congestion control commands from the sender)
2.5 E 5(.T)-.55 G(he feedback v)-5 E(olume of)-.2 E
(these congestion control)54 96 Q F1(NORM_ACK)2.5 E F0
(messages is controlled using the same timer)2.5 E
(-based probabilistic suppression techniques)-.2 E(as for)54 108 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)54 120 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)54 132 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.)54 144 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
156 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)54 168 Q -.15(ve)-.25 G 2.5(nw).15 G(hen dynamic congestion)
-2.5 E(control is enabled.)54 180 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)
54 192 Q(xistent TCP \215o)-.15 E(ws.)-.25 E/F2 10/Times-Bold@0 SF
(2.2 NORM Pr)36 216 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)54 240 Q(\(NORM\) Building Block document[15].)
54 252 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)54 264 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)54 276 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].)54 288 Q(Additionally)5 E 2.5
(,f)-.65 G(or congestion control, this document includes a baseline)-2.5
E(congestion control mechanism \(NORM-CC\) based on the TCP-Friendly Mu\
lticast Congestion Control \(TFMCC\) Building)54 300 Q
(Block described in [18].)54 312 Q F2(2.3 NORM Design T)36 336 Q
(radeoffs)-.74 E F0(While the v)54 360 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.)54 372 Q(There are numerous)5 E(engineering tradeof)54 384 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)54 396 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)54 408 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)54 420 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)54 432 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)54 444 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.)54 456 Q
(The ability of NORM to pro)54 480 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)54 492 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)54 504 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)54 516 Q(ork topology)-.1 E 5(.N)
-.65 G(ORM performs best when allo)-5 E(wed more b)-.25 E(uf)-.2 E
(fering resources than)-.25 E
(typical point-to-point transport protocols.)54 528 Q(This is because N\
ORM feedback suppression is based upon randomly-delayed)5 E
(transmissions from the recei)54 540 Q -.15(ve)-.25 G 2.5(rs).15 G
(et, rather than immediately transmitted feedback.)-2.5 E
(There are de\214niti)5 E .3 -.15(ve t)-.25 H(radeof).15 E(fs between)
-.25 E -.2(bu)54 552 S -.25(ff).2 G
(er 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 sizes allo)-.25 E 2.5(wt)-.25 G
(he NORM protocol to)-2.5 E(perform most ef)54 564 Q(\214ciently in lar)
-.25 E(ge delay-bandwidth topologies and allo)-.18 E 2.5(wf)-.25 G
(or longer feedback suppression back)-2.5 E(of)-.1 E 2.5(ft)-.25 G
(imeouts.)-2.5 E(This yields impro)54 576 Q -.15(ve)-.15 G 2.5(dg).15 G
(roup size scalability)-2.5 E 5(.N)-.65 G
(ORM can operate with reduced b)-5 E(uf)-.2 E(fering b)-.25 E
(ut at a cost of decreased ef)-.2 E(\214cienc)-.25 E(y)-.15 E(\(lo)54
588 Q(wer relati)-.25 E .3 -.15(ve g)-.25 H
(oodput\) and reduced group size scalability).15 E(.)-.65 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Times-Bold@0 SF(3.0 Conf)36 84 Q
(ormance Statement)-.25 E F0(This Protocol Instantiation document, in c\
onjunction with the Building Block documents identi\214ed in [15], [16]\
, [17], and)54 108 Q([18] completely speci\214es a w)54 120 Q(orking re\
liable multicast transport protocol that conforms to the requirements d\
escribed in RFC)-.1 E(2357 [3].)54 132 Q
(This document speci\214es the follo)54 156 Q
(wing message types and mechanisms which are REQ)-.25 E
(UIRED in complying NORM protocol)-.1 E(implementations:)54 168 Q .4 LW
538.7 190.5 69.7 190.5 DL(Message T)106.08 200 Q 189.77(ype Purpose)-.8
F 538.7 204.5 69.7 204.5 DL/F2 10/Courier@0 SF(NORM_DATA)74.7 214 Q F0
(Sender message for application data transmission.)209.7 214 Q
(Implementations must)5 E(support at least one of the)209.7 226 Q F2
(NORM_OBJECT_DATA)2.5 E F0(,)A F2(NORM_OBJECT_FILE)2.5 E F0 2.5(,o)C(r)
-2.5 E F2(NORM_OBJECT_STREAM)209.7 238 Q F0(deli)2.5 E -.15(ve)-.25 G
(ry services.).15 E(The use of the NORM FEC)5 E(Object T)209.7 250 Q
(ransmission Information header e)-.35 E(xtension is OPTION)-.15 E
(AL with)-.35 E F2(NORM_DATA)209.7 262 Q F0(messages.)2.5 E 538.7 266.5
69.7 266.5 DL F2(NORM_CMD\(FLUSH\))74.7 276 Q F0(Sender command to e)
209.7 276 Q(xcite recei)-.15 E -.15(ve)-.25 G
(rs for repair requests in lieu of ongoing).15 E(NORM_D)209.7 288 Q
-1.21 -1.11(AT A)-.4 H 2.5(transmissions. Note)3.61 F
(the use of the NORM_CMD\(FLUSH\) for)2.5 E(positi)209.7 300 Q .3 -.15
(ve a)-.25 H(ckno).15 E(wledgment of data receipt is OPTION)-.25 E(AL.)
-.35 E 538.7 304.5 69.7 304.5 DL F2(NORM_CMD\(SQUELCH\))74.7 314 Q F0
(Sender command to adv)209.7 314 Q(ertise its current v)-.15 E
(alid repair windo)-.25 E 2.5(wi)-.25 G 2.5(nr)-2.5 G(esponse to)-2.5 E
(in)209.7 326 Q -.25(va)-.4 G(lid requests for repair).25 E(.)-.55 E
538.7 330.5 69.7 330.5 DL F2(NORM_CMD\(REPAIR_ADV\))74.7 340 Q F0
(Sender command to adv)209.7 340 Q
(ertise current repair \(and congestion control state\) to)-.15 E
(group when unicast feedback messages are detected.)209.7 352 Q
(Used to control/suppress)5 E -.15(ex)209.7 364 S(cessi).15 E .3 -.15
(ve r)-.25 H(ecei).15 E -.15(ve)-.25 G 2.5(rf).15 G
(eedback in asymmetric multicast topologies.)-2.5 E 538.7 368.5 69.7
368.5 DL F2(NORM_CMD\(CC\))74.7 378 Q F0(Sender command used in collect\
ion of round trip timing and congestion control)209.7 378 Q
(status from group \(This may be OPTION)209.7 390 Q(AL if alternati)-.35
E .3 -.15(ve c)-.25 H(ongestion control).15 E
(mechanism and round trip timing collection is used\).)209.7 402 Q 538.7
406.5 69.7 406.5 DL F2(NORM_NACK)74.7 416 Q F0(Recei)209.7 416 Q -.15
(ve)-.25 G 2.5(rm).15 G
(essage used to request repair of missing transmitted content.)-2.5 E
538.7 420.5 69.7 420.5 DL F2(NORM_ACK)74.7 430 Q F0(Recei)209.7 430 Q
-.15(ve)-.25 G 2.5(rm).15 G(essage used to proacti)-2.5 E -.15(ve)-.25 G
(ly pro).15 E(vide feedback for congestion control)-.15 E 2.5
(purposes. Also)209.7 442 R(used with the OPTION)2.5 E(AL NORM Positi)
-.35 E .3 -.15(ve A)-.25 H(ckno).15 E(wledgement)-.25 E(Process.)209.7
454 Q 538.7 458.5 69.7 458.5 DL 538.7 190.5 538.7 458.5 DL 69.7 190.5
69.7 458.5 DL 202.2 190.5 202.2 458.5 DL(Adamson, Bormann, et al.)36 696
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(This document also describes the follo)54 84 Q
(wing message types and associated mechanisms which are OPTION)-.25 E
(AL for complying)-.35 E(NORM protocol implementations:)54 96 Q .4 LW
542.95 118.5 65.45 118.5 DL(Message T)106.08 128 Q 194.02(ype Purpose)
-.8 F 542.95 132.5 65.45 132.5 DL/F1 10/Courier@0 SF(NORM_INFO)70.45 142
Q F0(Sender message for pro)213.95 142 Q(viding ancillary conte)-.15 E
(xt information associated with)-.15 E(NORM transport objects.)213.95
154 Q(The use of the NORM FEC Object T)5 E(ransmission)-.35 E
(Information header e)213.95 166 Q(xtension is OPTION)-.15 E(AL with)
-.35 E F1(NORM_INFO)2.5 E F0(messages.)2.5 E 542.95 170.5 65.45 170.5 DL
F1(NORM_CMD\(EOT\))70.45 180 Q F0(Sender command to indicate it has rea\
ch end-of-transmission and will no longer)213.95 180 Q
(respond to repair requests.)213.95 192 Q 542.95 196.5 65.45 196.5 DL F1
(NORM_CMD\(ACK_REQ\))70.45 206 Q F0
(Sender command to support application-de\214ned, positi)213.95 206 Q
-.15(ve)-.25 G(ly ackno).15 E(wledged)-.25 E
(commands sent outside of the conte)213.95 218 Q(xt of the b)-.15 E
(ulk data content being transmitted.)-.2 E(The NORM Positi)213.95 230 Q
.3 -.15(ve A)-.25 H(ckno).15 E
(wledgement Procedure associated with this message)-.25 E
(type is OPTION)213.95 242 Q(AL.)-.35 E 542.95 246.5 65.45 246.5 DL F1
(NORM_CMD\(APPLICATION\))70.45 256 Q F0(Sender command containing appli\
cation-de\214ned commands sent outside of the)213.95 256 Q(conte)213.95
268 Q(xt of the b)-.15 E(ulk data content being transmitted.)-.2 E
542.95 272.5 65.45 272.5 DL F1(NORM_REPORT)70.45 282 Q F0
(Optional message type reserv)213.95 282 Q(ed for e)-.15 E
(xperimental implementations of the NORM)-.15 E(protocol.)213.95 294 Q
542.95 298.5 65.45 298.5 DL 542.95 118.5 542.95 298.5 DL 65.45 118.5
65.45 298.5 DL 206.45 118.5 206.45 298.5 DL/F2 10/Times-Bold@0 SF
(4.0 NORM Message F)36 324 Q(ormats)-.25 E F0
(As mentioned in Section 2.1, there are tw)54 348 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(NORM_CMD)54 360 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)54 372 Q F0
(messages generated by recei)2.5 E -.15(ve)-.25 G(rs within a).15 E/F3
10/Times-Italic@0 SF(NormSession)2.5 E F0 5(.A)C 2.5(na)-5 G
(uxillary message type of NORM_REPOR)-2.5 E 2.5(Ti)-.6 G 2.5(sa)-2.5 G
(lso)-2.5 E(pro)54 384 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)54 396 Q -.15(ve)-.25 G
2.5(ni).15 G 2.5(nS)-2.5 G(ection 5.0.)-2.5 E(Indi)54 408 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
420 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)54 432 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)54 444 Q
(orks.)-.1 E F2(4.1 NORM Common Message Header and Extensions)36 468 Q
F0(There are some common message \214elds contained in all NORM message\
 types.)54 492 Q(Additionally)5 E 2.5(,ah)-.65 G(eader e)-2.5 E
(xtension)-.15 E(mechanism is de\214ned to e)54 504 Q
(xpand the functionality of the NORM protocol without re)-.15 E
(vision to this document.)-.25 E(All NORM)5 E(protocol messages be)54
516 Q(gin with a common header with information \214elds as follo)-.15 E
(ws:)-.25 E F1 114(0123)124.2 540 S 6(01234567890123456789012345678901)
118.2 552 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
564 Q 6(|version| type)109.2 576 R 24(|h)6 G 18(dr_len |)-24 F 72
(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
588 Q 162(|s)109.2 600 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
612 Q F3(NORM Common Messa)220.115 636 Q .2 -.1(ge H)-.1 H(eader F).1 E
(ormat)-1.05 E F0(Adamson, Bormann, 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
(June 2003)185.175 E(The "v)54 84 Q(ersion" \214eld is a 4-bit v)-.15 E
(alue indicating the protocol v)-.25 E(ersion number)-.15 E 5(.N)-.55 G
(ORM implementations SHOULD ignore)-5 E(recei)54 96 Q -.15(ve)-.25 G 2.5
(dm).15 G(essages with v)-2.5 E(ersion numbers dif)-.15 E
(ferent from their o)-.25 E
(wn. This number is intended to indicate and distinguish)-.25 E
(upgrades of the protocol which may be non-interoperable.)54 108 Q
(The NORM v)5 E(ersion number for this speci\214cation is 1.)-.15 E
(The message "type" \214eld is a 4-bit v)54 132 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)
267.82 162 R(alue)-1.11 E/F1 10/Courier@0 SF(NORM_INFO)252.315 186 Q F0
(1)35.885 E F1(NORM_DATA)252.315 198 Q F0(2)35.885 E F1(NORM_CMD)252.315
210 Q F0(3)41.885 E F1(NORM_NACK)252.315 222 Q F0(4)35.885 E F1
(NORM_ACK)252.315 234 Q F0(5)41.885 E F1(NORM_REPORT)252.315 246 Q F0(6)
23.885 E(The 8-bit "hdr_len" \214eld indicates the number of 32-bit w)54
276 Q(ords that comprise the gi)-.1 E -.15(ve)-.25 G 2.5(nm).15 G
(essage')-2.5 E 2.5(sh)-.55 G(eader portion.)-2.5 E(This is)5 E
(used to f)54 288 Q(acilitate header e)-.1 E
(xtensions that may be applied.)-.15 E(The presence of header e)5 E
(xtensions are implied when the "hdr_len")-.15 E -.25(va)54 300 S
(lue is greater than the base v).25 E(alue for the gi)-.25 E -.15(ve)
-.25 G 2.5(nm).15 G(essage "type".)-2.5 E
(The "sequence" \214eld is a 16-bit v)54 324 Q(alue that is set by the \
message originator as a monotonically increasing number)-.25 E
(incremented with each NORM message transmitted to a gi)54 336 Q -.15
(ve)-.25 G 2.5(nd).15 G(estination address.)-2.5 E 2.5(A")5 G
(sequence" \214eld number space)-2.5 E
(SHOULD be maintained for messages sent to the)54 348 Q/F2 10
/Times-Italic@0 SF(NormSession)2.5 E F0(group address.)2.5 E(This v)5 E
(alue can be monitored by recei)-.25 E(ving)-.25 E(nodes to detect pack)
54 360 Q
(et losses in the transmission from a sender and used in estimating ra)
-.1 E 2.5(wp)-.15 G(ack)-2.5 E(et loss for congestion control)-.1 E 2.5
(purposes. Note)54 372 R(that this v)2.5 E(alue is NO)-.25 E 2.5(Tu)-.4
G(sed in the NORM protocol to detect missing reliable data content and \
does NO)-2.5 E(T)-.4 E
(identify the application data or FEC payload that may be attached.)54
384 Q -.4(Wi)5 G(th message authentication, the "sequence" \214eld may)
.4 E(also be le)54 396 Q -.15(ve)-.25 G(raged for protection from messa\
ge "replay" attacks, particularly of NORM_N).15 E -.4(AC)-.35 G 2.5(Ko)
.4 G 2.5(ro)-2.5 G(ther feedback messages.)-2.5 E
(In this case, the recei)54 408 Q -.15(ve)-.25 G 2.5(rn).15 G(ode shoul\
d maintain a monotonically increasing "sequence" \214eld space for each\
 destination to)-2.5 E(which it transmits \(This may be multiple destin\
ations when unicast feedback is used\).)54 420 Q
(The size of this \214eld is intended to be)5 E(suf)54 432 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-bandwidth product of e)-.1 E(xpected netw)-.15
E(ork)-.1 E(connections.)54 444 Q(The "source_id" \214eld is a 32-bit v)
54 468 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(\()54
480 Q F2(NormNodeId)A F0 2.5(\)c)C
(an be set according to application needs b)-2.5 E
(ut unique identi\214ers must be assigned within a single)-.2 E F2
(NormSession)54 492 Q F0 5(.I)C 2.5(ns)-5 G
(ome 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.)
54 504 Q -.15(Fo)5 G(r).15 E -.15(ex)54 516 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.)54 528 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.)54 540 Q/F3 10/Times-BoldItalic@0 SF
(NORM Header Extensions)54 564 Q F0(When header e)54 588 Q
(xtensions are applied, the)-.15 E 2.5(yf)-.15 G(ollo)-2.5 E 2.5(wt)-.25
G(he message type')-2.5 E 2.5(sb)-.55 G(ase header and precede an)-2.5 E
2.5(yp)-.15 G(ayload portion.)-2.5 E(There are)5 E(tw)54 600 Q 2.5(of)
-.1 G(ormats for header e)-2.5 E(xtensions, both of which be)-.15 E
(gin with an 8-bit "e)-.15 E(xt_type" \(header e)-.15 E
(xtension type\) \214eld.)-.15 E(One format is)5 E(pro)54 612 Q
(vided for v)-.15 E(ariable-length e)-.25 E(xtensions with "e)-.15 E
(xt_type" v)-.15 E(alues in the range from 0 through 127.)-.25 E
(The other format is for)5 E<8c78>54 624 Q(ed length \(one 32-bit w)-.15
E(ord\) e)-.1 E(xtensions with "e)-.15 E(xt_type" v)-.15 E
(alues in the range from 128 through 255.)-.25 E(These formats are)5 E
(gi)54 636 Q -.15(ve)-.25 G 2.5(nh).15 G(ere:)-2.5 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q 6(|e)109.2 120 S(xt_type <=127|)-6 E 18(ext_len |)24 F(|)186 E 180
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |)109.2 132 R 120(|H)109.2 144 S
(eader Extension Content)-120 E(|)114 E 180(|.)109.2 156 S 174(.. |)-180
F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 168 Q/F2 10/Times-Italic@0 SF(NORM V)203.76 192 Q
(ariable Length Header Extension F)-1.11 E(ormat)-1.05 E F1 114(0123)
124.2 216 S 6(01234567890123456789012345678901)118.2 228 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
240 Q 6(|e)109.2 252 S(xt_type >=128|)-6 E 18(ext_len | Header)24 F
(Extension Content)6 E(|)18 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
264 Q F2(NORM F)193.02 276 Q(ixed Length \(32-bit\) Header Extension F)
-.45 E(ormat)-1.05 E F0
(The "Header Extension Content" portion of these header e)54 300 Q
(xtension format is de\214ned for each header e)-.15 E
(xtension type de\214ned)-.15 E(for NORM messages.)54 312 Q
(Some header e)5 E(xtensions are de\214ned within this document for NOR\
M baseline FEC and congestion)-.15 E(control operations.)54 324 Q/F3 10
/Times-Bold@0 SF(4.2 NORM Sender Messages)36 360 Q F0
(NORM sender messages include the)54 384 Q F1(NORM_DATA)2.5 E F0
(type, the)2.5 E F1(NORM_INFO)2.5 E F0(type, and the)2.5 E F1(NORM_CMD)
2.5 E F0(type.)2.5 E F1(NORM_DATA)5 E F0(and)2.5 E F1(NORM_INFO)54 396 Q
F0(messages contain application data content while)2.5 E F1(NORM_CMD)2.5
E F0(messages are used for v)2.5 E(arious protocol control)-.25 E
(functions.)54 408 Q F3(4.2.1 NORM_D)54 432 Q -1.5 -.95(AT A)-.35 H
(Message)3.45 E F0(The)54 456 Q F1(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)54 468 Q
(gmented data content for objects of type)-.15 E F1(NORM_OBJECT_DATA)2.5
E F0(,)A F1(NORM_OBJECT_FILE)2.5 E F0 2.5(,a)C(nd)-2.5 E F1
(NORM_OBJECT_STREAM)54 480 Q F0(.)A F1(NORM_DATA)5 E F0
(messages may contain original or FEC-encoded application data content.)
2.5 E(The format of)54 504 Q F1(NORM_DATA)2.5 E F0
(messages is comprised of three logical portions: 1\) a \214x)2.5 E
(ed-format)-.15 E F1(NORM_DATA)2.5 E F0(header portion,)2.5 E
(2\) an FEC P)54 516 Q(ayload ID portion with a format dependent upon t\
he FEC encoding used, and 3\) a payload portion that includes)-.15 E
(length and of)54 528 Q
(fset \214elds as well as application data content.)-.25 E(Additionally)
5 E 2.5(,N)-.65 G(ORM implementations MA)-2.5 E 2.5(Ye)-1.05 G
(xtend the)-2.65 E F1(NORM_DATA)54 540 Q F0
(header to include an FEC Object T)2.5 E
(ransmission Information \(FTI\) header e)-.35 E 2.5(xtension. This)-.15
F(allo)2.5 E(ws NORM)-.25 E(recei)54 552 Q -.15(ve)-.25 G(rs to automat\
ically allocate resources and properly perform FEC decoding without the\
 need for pre-con\214guration or).15 E(out-of-band information.)54 564 Q
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 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
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q(|version| type=2|)109.2 120 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 162(|s)109.2 144 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 60(|s)109.2 168 S 60(ession_id |)-60 F 30(grtt |)30 F 24(gsize |)
30 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 180 Q 30(|f)109.2 192 S 24(lags |)-30 F 24
(fec_id | object_transport_id)24 F(|)42 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 150(|f)109.2 216 S 138(ec_payload_id |)-150 F 180(|.)109.2 228 S
174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
240 Q 96(|h)109.2 252 S(eader_extensions \(if applicable\))-96 E(|)84 E
180(|.)109.2 264 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
276 Q 60(|p)109.2 288 S 48(ayload_len* |)-60 F(payload_offset \(msb\)*)
30 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
300 Q 132(|p)109.2 312 S(ayload_offset \(lsb\)*)-132 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
324 Q 156(|p)109.2 336 S 138(ayload_data* |)-156 F 180(|.)109.2 348 S
174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
360 Q/F2 10/Times-Italic@0 SF(NORM_D)241.275 384 Q -.37(AT)-.35 G 2.5
(AM)-.13 G(essa)-2.5 E .2 -.1(ge F)-.1 H(ormat)-.95 E(*NO)54 408 Q 2.5
(TE: The)-.4 F("payload_len" and "payload_of)2.5 E
(fset" \214elds in the payload portion of)-.18 E F1(NORM_DATA)2.5 E F2
(messa)2.5 E -.1(ge)-.1 G 2.5(sa).1 G .74 -.37(re p)-2.5 H -.37(re).37 G
(sent only).37 E(when systematic FEC codes \(e)54 420 Q(.g)-.15 E
(., "fec_id" = 129\) ar)-.15 E 2.5(eu)-.37 G 2.5(sed. F)-2.5 F(or suc)
-1.05 E 2.5(hF)-.15 G
(EC codes, these \214elds contain actual length and)-2.5 E(of)54 432 Q
(fset values for the encapsulated application data se)-.18 E(gment for)
-.4 E F1(NORM_DATA)2.5 E F2(messa)2.5 E -.1(ge)-.1 G 2.5(sc).1 G
(ontaining original data information.)-2.5 E(Howe)54 444 Q(ver)-.15 E
2.5(,i)-1.11 G(n)-2.5 E F1(NORM_DATA)2.5 E F2(messa)2.5 E -.1(ge)-.1 G
2.5(sc).1 G(ontaining parity information for a coding bloc)-2.5 E
(k, these \214elds ar)-.2 E 2.5(en)-.37 G(ot actual length or)-2.5 E(of)
54 456 Q(fset values b)-.18 E(ut ar)-.2 E 2.5(ei)-.37 G
(nstead values computed fr)-2.5 E
(om FEC encoding of the "payload_len" and "payload_of)-.45 E
(fset" \214elds of the)-.18 E(_data_ se)54 468 Q
(gments of the applicable coding bloc)-.4 E 2.5(k. F)-.2 F
(or systematic FEC codes, parity se)-1.05 E
(gments can be identi\214ed as se)-.4 E(gments)-.4 E(wher)54 480 Q 2.5
(e")-.37 G(encoding_symbol_id >= sour)-2.5 E(ce_bloc)-.37 E
(k_len", while data se)-.2 E(gments ar)-.4 E 2.5(et)-.37 G(hose wher)
-2.5 E 2.5(e")-.37 G(encoding_symbol_id <)-2.5 E(sour)54 492 Q(ce_bloc)
-.37 E(k_len".)-.2 E F0(The "v)54 516 Q(ersion", "type", "hdr_len", "se\
quence", and "source_id" \214elds form the NORM Common Message Header a\
s)-.15 E(described in Section 4.1.)54 528 Q(The v)5 E(alue of the)-.25 E
F1(NORM_DATA)2.5 E F0("type" \214eld is 2.)2.5 E(The)5 E F1(NORM_DATA)
2.5 E F0(_base_ "hdr_len" v)2.5 E(alue is 4)-.25 E(\(32-bit w)54 540 Q
(ords\) plus the size of the "fec_payload_id" \214eld.)-.1 E
(The "fec_payload_id" \214eld size depends upon the FEC encoding)5 E
(used for the referenced)54 552 Q F2(NormObject)2.5 E F0 5(.T)C
(he "fec_id" \214eld is used to indicate the FEC coding type.)-5 E -.15
(Fo)5 G 2.5(re).15 G(xample, when small)-2.65 E
(block, systematic codes are used, a "fec_id" v)54 564 Q
(alue of 129 is indicated and the size of the "fec_payload_id" is tw)
-.25 E 2.5(o3)-.1 G(2-bit)-2.5 E -.1(wo)54 576 S 2.5(rds. In).1 F
(this case the)2.5 E F1(NORM_DATA)2.5 E F0(base "hdr_len" v)2.5 E
(alue is 6.)-.25 E(The cumulati)5 E .3 -.15(ve s)-.25 H(ize of an).15 E
2.5(yh)-.15 G(eader e)-2.5 E(xtensions applied is)-.15 E
(added into the "hdr_len" \214eld.)54 588 Q
(The "session_id" \214eld contains a v)54 612 Q(alue generated by the s\
ender to uniquely identify its current instance of parcipitation in the)
-.25 E F2(NormSession)54 624 Q F0 5(.T)C(his allo)-5 E(ws recei)-.25 E
-.15(ve)-.25 G(rs to detect senders who ha).15 E .3 -.15(ve p)-.2 H
(erhaps left and rejoined a session in progress.).15 E(When a)5 E
(sender \(identi\214ed by its "source_id"\) is detected to ha)54 636 Q
.3 -.15(ve a n)-.2 H .5 -.25(ew ").15 H(session_id", the NORM recei).25
E -.15(ve)-.25 G(rs SHALL drop their).15 E(pre)54 648 Q
(vious state on the sender and be)-.25 E(gin reception ane)-.15 E -.65
(w.)-.25 G(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)
105.89 E([P)119.09 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
(June 2003)185.175 E(The "grtt" \214eld contains a non-linear quantized\
 representation of the sender')54 84 Q 2.5(sc)-.55 G
(urrent estimate of group round-trip time)-2.5 E(\(GR)54 96 Q
(TT\) \(This is also referred to as)-.6 E/F1 10/Courier@0 SF(R_max)2.5 E
F0(in the TFMCC Building Block [18]\).)2.5 E(This v)5 E
(alue is used to control timing of the)-.25 E -.35(NA)54 108 S(CK repai\
r process and other aspects of protocol operation as described in this \
document.)-.05 E(The algorithm for encoding and)5 E(decoding this \214e\
ld is described in the RMT NORM Building Block document[15].)54 120 Q
(The "gsize" \214eld contains a representation of the sender')54 144 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)54 156 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)54 168 Q(xponent \(order of magnitude\))-.15 E
(information in the 4 least signi\214cant bits.)54 180 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)54 192 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)54 204 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)54 216 Q
(gree of precision to appropriately scale back)-.15 E(of)-.1 E 2.5(ft)
-.25 G(imers, etc.)-2.5 E
(The "\215ags" \214eld contains a number of dif)54 252 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.)54 264 Q
(De\214ned \215ags in this \214eld include:)5 E .4 LW 539.585 286.5
68.815 286.5 DL 63.61(Flag V)124.925 296 R 140.39(alue Purpose)-1.11 F
539.585 300.5 68.815 300.5 DL F1(NORM_FLAG_REPAIR)73.815 310 Q F0(0x01)
40.385 E(Indicates message is a repair transmission)246.585 310 Q
539.585 314.5 68.815 314.5 DL F1(NORM_FLAG_EXPLICIT)73.815 324 Q F0
(0x02)28.385 E(Indicates a repair se)246.585 324 Q
(gment intended to meet a speci\214c recei)-.15 E -.15(ve)-.25 G 2.5(re)
.15 G(rasure,)-2.5 E(as compared to parity se)246.585 336 Q(gments pro)
-.15 E(vided by the sender for general)-.15 E
(purpose \(with respect to an FEC coding block\) erasure \214lling.)
246.585 348 Q 539.585 352.5 68.815 352.5 DL F1(NORM_FLAG_INFO)73.815 362
Q F0(0x04)52.385 E(Indicates a)246.585 362 Q -.25(va)-.2 G(ilability of)
.25 E F1(NORM_INFO)2.5 E F0(for object.)2.5 E 539.585 366.5 68.815 366.5
DL F1(NORM_FLAG_UNRELIABLE)73.815 376 Q F0(0x08)16.385 E
(Indicates that repair transmissions for the speci\214ed object will be)
246.585 376 Q(una)246.585 388 Q -.25(va)-.2 G
(ilable \(One-shot, best ef).25 E(fort transmission\).)-.25 E 539.585
392.5 68.815 392.5 DL F1(NORM_FLAG_FILE)73.815 402 Q F0(0x10)52.385 E
(Indicates object is "\214le-based" data \(hint to use disk storage for)
246.585 402 Q(reception\).)246.585 414 Q 539.585 418.5 68.815 418.5 DL
F1(NORM_FLAG_STREAM)73.815 428 Q F0(0x20)40.385 E
(Indicates object is of type NORM_OBJECT_STREAM.)246.585 428 Q 539.585
432.5 68.815 432.5 DL F1(NORM_FLAG_MSG_START)73.815 442 Q F0(0x20)22.385
E(Marks the \214rst se)246.585 442 Q
(gment of application messages embedded in)-.15 E(NORM_OBJECT_STREAMs.)
246.585 454 Q 539.585 458.5 68.815 458.5 DL 539.585 286.5 539.585 458.5
DL 68.815 286.5 68.815 458.5 DL 239.085 286.5 239.085 458.5 DL 201.315
286.5 201.315 458.5 DL(The)54 484 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)54 496 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)54 508 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)54 520 Q
(xhausted its ability to pro)-.15 E(vide "fresh" \(pre)-.15 E
(viously untransmitted\) parity se)-.25 E(gments as)-.15 E(repair)54 532
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)54 544 Q(ferent le)-.25 E
(gs of a reliable multicast topology with disparate repair needs. The)
-.15 E F1(NORM_FLAG_INFO)54 556 Q F0(\215ag is set only when optional)
2.5 E F1(NORM_INFO)2.5 E F0(content is actually a)2.5 E -.25(va)-.2 G
(ilable for the associated object.).25 E(Thus, recei)54 568 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
(ilable for a gi).25 E -.15(ve)-.25 G 2.5(no).15 G 2.5(bject. The)-2.5 F
F1(NORM_FLAG_UNRELIABLE)54 580 Q F0(\215ag is set when the sender wishe\
s to transmit an object with only "best ef)2.5 E(fort" deli)-.25 E -.15
(ve)-.25 G(ry and).15 E
(will not supply repair transmissions for the object.)54 592 Q
(NORM recei)5 E -.15(ve)-.25 G(rs SHOULD NO).15 E 2.5(Te)-.4 G -.15(xe)
-2.65 G(cute repair requests for objects).15 E(mark)54 604 Q
(ed with the)-.1 E F1(NORM_FLAG_UNRELIABLE)2.5 E F0 2.5(\215ag. Note)2.5
F(that recei)2.5 E -.15(ve)-.25 G(rs may inadv).15 E
(ertently request repair of such objects)-.15 E(when all se)54 616 Q
(gments \(or info content\) for those objects are not recei)-.15 E -.15
(ve)-.25 G 2.5(d\().15 G(i.e. a g)-2.5 E
(ap in the "object_transport_id" sequence is)-.05 E 2.5(noted\). In)54
628 R(this case, the sender should in)2.5 E -.2(vo)-.4 G .2 -.1(ke t).2
H(he).1 E F1(NORM_CMD\(SQUELCH\))2.5 E F0
(process as described in Section 4.2.3.)2.5 E(The)54 652 Q 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 non-)2.5 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 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
(June 2003)185.175 E -.2(vo)54 84 S(latile storage.).2 E(The)5 E/F1 10
/Courier@0 SF(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(When the)54 96 Q F1(NORM_FLAG_STREAM)
2.5 E F0(\215ag is set, the)2.5 E F1(NORM_FLAG_MSG_START)2.5 E F0
(can be optionally used to mark the \214rst data)2.5 E(se)54 108 Q(gmen\
ts of application-layer messages transported within the NORM stream.)
-.15 E(This allo)5 E(ws NORM recei)-.25 E -.15(ve)-.25 G 2.5(ra).15 G
(pplications to)-2.5 E("synchronize" with NORM senders and to be able t\
o properly interpret application layer data when joining a NORM session)
54 120 Q(already in progress.)54 132 Q
(In practice, the NORM implementation MA)5 E 2.5(Ys)-1.05 G
(et this \215ag for the se)-2.5 E(gment transmitted follo)-.15 E
(wing an)-.25 E -.15(ex)54 144 S
(plicit "\215ush" of the stream by the application.).15 E(The "fec_id" \
\214eld corresponds to the FEC Encoding Identi\214er described in the F\
EC Building Block document [17].)54 168 Q(The)5 E("fec_id" v)54 180 Q(a\
lue implies the format of the "fec_payload_id" \214eld and, coupled wit\
h FEC Object T)-.25 E(ransmission Information, the)-.35 E
(procedures to decode FEC encoded content.)54 192 Q
(Small block, systematic codes \("fec_id" = 129\) are e)5 E
(xpected to be used for)-.15 E(most NORM purposes and the)54 204 Q F1
(NORM_OBJECT_STREAM)2.5 E F0(requires systematic FEC codes for most ef)
2.5 E(\214cient performance.)-.25 E(The "object_transport_id" \214eld i\
s a monotonically and incrementally increasing v)54 228 Q
(alue assigned by the sender to)-.25 E/F2 10/Times-Italic@0 SF
(NormObjects)54 240 Q F0(being transmitted.)2.5 E -.35(Tr)5 G(ansmissio\
ns and repair requests related to that object use the same "object_tran\
sport_id").35 E -.25(va)54 252 S 2.5(lue. F).25 F(or sessions of v)-.15
E(ery long or inde\214nite duration, the "object_transport_id" \214eld \
may be repeated, b)-.15 E(ut it is presumed)-.2 E
(that the 16-bit \214eld size pro)54 264 Q
(vides an adequate enough sequence space to a)-.15 E -.2(vo)-.2 G
(id object confusion amongst recei).2 E -.15(ve)-.25 G(rs and).15 E
(sources \(i.e. recei)54 276 Q -.15(ve)-.25 G
(rs SHOULD re-synchronize with a serv).15 E(er when recei)-.15 E
(ving object sequence identi\214ers suf)-.25 E(\214ciently out-of-)-.25
E(range with the current state k)54 288 Q(ept for a gi)-.1 E -.15(ve)
-.25 G 2.5(ns).15 G 2.5(ource\). During)-2.5 F
(the course of its transmission within a NORM session, an)2.5 E(object \
is uniquely identi\214ed by the concatenation of the sender "source_id"\
 and the gi)54 300 Q -.15(ve)-.25 G 2.5(n").15 G 2.5
(object_transport_id". Note)-2.5 F(that)2.5 E F1(NORM_INFO)54 312 Q F0(\
messages associated with the identi\214ed object carry the same "object\
_transport_id" v)2.5 E(alue.)-.25 E
(The "fec_payload_id" identi\214es the attached)54 336 Q F1(NORM_DATA)
2.5 E F0("payload" content.)2.5 E(The size and format of of the)5 E("fe\
c_payload_id" \214eld depends upon the FEC type indicated by the "fec_i\
d" \214eld.)54 348 Q(These formats are gi)5 E -.15(ve)-.25 G 2.5(ni).15
G 2.5(nt)-2.5 G(he FEC)-2.5 E(Building Block document [17] and an)54 360
Q 2.5(ys)-.15 G(ubsequent e)-2.5 E(xtensions of that document.)-.15 E
(As an e)5 E(xample, the format of the)-.15 E("fec_payload_id" format s\
mall block, systematic codes \("fec_id" = 129\) gi)54 372 Q -.15(ve)-.25
G 2.5(nh).15 G(ere:)-2.5 E F1
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
396 Q 138(|s)109.2 408 S 120(ource_block_number |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
420 Q 48(|s)109.2 432 S 36(ource_block_len |)-48 F 36
(encoding_symbol_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
444 Q F2(Small Bloc)158.205 468 Q
(k, Systematic Code \("fec_id" = 129\) "fec_payload_id" F)-.2 E(ormat)
-1.05 E F0(The "source_block_number", "source_block_len", and "encoding\
_symbol_id" \214elds correspond to the "Source Block)54 492 Q(Number", \
"Source Block Length, and "Encoding Symbol ID" \214elds of the FEC P)54
504 Q(ayload ID format gi)-.15 E -.15(ve)-.25 G 2.5(nb).15 G 2.5(yt)-2.5
G(he FEC)-2.5 E(Building Block document[17].)54 516 Q
(The "source_block_number" identi\214es the coding block')5 E 2.5(sr)
-.55 G(elati)-2.5 E .3 -.15(ve p)-.25 H(osition with a).15 E F2
(NormObject)54 528 Q F0 5(.N)C(ote that, for)-5 E F2(NormObjects)2.5 E
F0(of type)2.5 E F1(NORM_OBJECT_STREAM)2.5 E F0 2.5(,t)C
(he "source_block_number" may wrap for)-2.5 E -.15(ve)54 540 S
(ry long li).15 E -.15(ve)-.25 G 2.5(ds).15 G 2.5(essions. The)-2.5 F
("source_block_len" indicates the number of user data se)2.5 E
(gments in the identi\214ed coding block.)-.15 E(Gi)54 552 Q -.15(ve)
-.25 G 2.5(nt).15 G(he "source_block_len" information of ho)-2.5 E 2.5
(wm)-.25 G(an)-2.5 E 2.5(ys)-.15 G
(ymbols of application data are contained in the block, the recei)-2.5 E
-.15(ve)-.25 G(r).15 E(can determine whether the attached se)54 564 Q
(gment is data or parity content and treat it appropriately)-.15 E 5(.T)
-.65 G(he "encoding_symbol_id")-5 E
(identi\214es which speci\214c symbol \(se)54 576 Q
(gment\) 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)-.25 E(of the "\
encoding_symbol_id" and the associated "source_block_len" parameters fo\
r the block, the symbol \(se)54 588 Q(gment\))-.15 E
(referenced may be a user data or an FEC parity se)54 600 Q 2.5
(gment. F)-.15 F
(or systematic codes, encoding symbols numbered less than the)-.15 E F1
(source_block_len)54 612 Q F0
(contain original application data while se)2.5 E
(gments greater than or equal to)-.15 E F1(source_block_len)2.5 E F0
(contain parity symbols calculated for the block.)54 624 Q
(Additional FEC Object T)54 648 Q(ransmission Information \(as describe\
d in the FEC Building Block document[17]\) is required to)-.35 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 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
(June 2003)185.175 E(properly recei)54 84 Q .3 -.15(ve a)-.25 H
(nd decode NORM transport objects.).15 E(This information MA)5 E 2.5(Yb)
-1.05 G 2.5(ep)-2.5 G(ro)-2.5 E(vided as out-of-band session)-.15 E 2.5
(information. Ho)54 96 R(we)-.25 E -.15(ve)-.25 G .8 -.4(r, i).15 H 2.5
(ns).4 G(ome cases, it may be useful for the sender to include this inf\
ormation "in band" to f)-2.5 E(acilitate)-.1 E(recei)54 108 Q -.15(ve)
-.25 G 2.5(ro).15 G(peration with minimal precon\214guration.)-2.5 E
-.15(Fo)5 G 2.5(rt).15 G(his purpose, the NORM FEC Object T)-2.5 E
(ransmission Information \(FTI\))-.35 E(Header Extension is de\214ned.)
54 120 Q(This header e)5 E(xtension MA)-.15 E 2.5(Yb)-1.05 G 2.5(ea)-2.5
G(pplied to)-2.5 E/F1 10/Courier@0 SF(NORM_DATA)2.5 E F0(and)2.5 E F1
(NORM_INFO)2.5 E F0(messages to pro)2.5 E(vide)-.15 E
(this necessary information.)54 132 Q(The e)5 E(xact format of the e)
-.15 E(xtension depends upon the FEC code in use, b)-.15 E
(ut in general it SHOULD)-.2 E(contain an)54 144 Q 2.5(yr)-.15 G(equire\
d details on the FEC code in use \(e.g., FEC Instance ID, etc\) and the\
 byte size of the associated)-2.5 E/F2 10/Times-Italic@0 SF(NormObject)
54 156 Q F0(\(F)2.5 E(or the)-.15 E F1(NORM_OBJECT_STREAM)2.5 E F0
(type, this size corresponds to the stream b)2.5 E(uf)-.2 E
(fer size maintained by the)-.25 E(NORM sender\).)54 168 Q(As an e)5 E(\
xample, the format of the FTI Header Extension for small block systemat\
ic codes \("fec_id" = 129\))-.15 E(is gi)54 180 Q -.15(ve)-.25 G 2.5(nh)
.15 G(ere:)-2.5 E F1
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 12(|e)109.2 216 S(xt_type = 1 |)-12 E(ext_len = 4)12 E 48(|f)12 G
42(ec_instance_id |)-48 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
228 Q 36(|f)109.2 240 S 42(ec_max_block_len |)-36 F 42(fec_num_parity |)
54 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 252 Q 60(|s)109.2 264 S 48(egment_size |)-60 F
(object_size \(msb\))42 E(|)42 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
276 Q 138(|o)109.2 288 S(bject_size \(lsb\))-138 E(|)138 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
300 Q F2(NORM FEC Object T)71.535 324 Q -.15(ra)-.55 G
(nsmission Information Header Extension for Small Bloc).15 E 2.5(kS)-.2
G(ystematic Codes \("fec_id" = 129\))-2.5 E F0(The "e)54 348 Q
(xt_type" v)-.15 E(alue for this header e)-.25 E(xtension is 1.)-.15 E
(The "e)5 E
(xt_len" depends upon the format of the FTI for FEC code type)-.15 E
(identifed by the "fec_id" \214eld.)54 360 Q(The "fec_instance_id" corr\
esponds to the "FEC Instance ID" described in the FEC Building Block do\
cument[17].)54 384 Q(In this)5 E
(case, the "fec_instance_id" SHALL be a v)54 396 Q(alue corresponding t\
o the particular type of Small Block Systematic Code being)-.25 E
(used \(e.g., Reed-Solomon GF\(2^8\), Reed-Solomon GF\(2^16\), etc\).)54
408 Q(The standardized assignment of FEC Instance ID v)5 E(alues)-.25 E
(is described in [17].)54 420 Q(The "fec_max_block_len" indicates the c\
urrent maximum number of user data se)54 444 Q
(gments per FEC coding block to be used by)-.15 E
(the sender during the session.)54 456 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)54 468 Q(.)-.55 E(The "fec_num_parity" corresponds to the "\
maximum number of of encoding symbols that can be generated for an)54
492 Q 2.5(ys)-.15 G(ource)-2.5 E
(block" as described in for FEC Object T)54 504 Q(ransmission Informati\
on for Small Block Systematic Codes in the FEC Building)-.35 E
(Block document [17].)54 516 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)54 528 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)54 540 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)54 552 Q 2.5(ya)-.15 G(re de\214ned.)-2.5
E(The "se)54 576 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)54 588 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
600 Q -.15(ve)-.25 G 2.5(dd).15 G(ata messaging.)-2.5 E(The 48-bit "obj\
ect_size" \214eld indicates the total size of the object \(in bytes\) f\
or the static object types of)54 624 Q F1(NORM_OBJECT_FILE)54 636 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)54 648 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
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(fore)54 84 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 10/Courier@0 SF
(NORM_OBJECT_STREAM)54 96 Q F0 2.5(,t)C(he "object_size" \214eld is use\
d by the sender to indicate the size of its stream b)-2.5 E(uf)-.2 E
(fer to the)-.25 E(recei)54 108 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.)54 120 Q
(The concatenation of)54 144 Q/F2 10/Times-Italic@0 SF(objectId::fecP)
2.5 E(ayloadId)-.8 E F0(can be vie)2.5 E(wed as a unique transport data\
 unit \(TPDU\) identi\214er for the attached)-.25 E(se)54 156 Q
(gment with respect to the NORM sender)-.15 E(.)-.55 E
(The "payload_len" and "payload_of)54 180 Q
(fset" \214elds are used to specify the size and relati)-.25 E .3 -.15
(ve p)-.25 H(osition \(within the).15 E F2(NormObject)2.5 E F0 2.5(\)o)C
(f)-2.5 E(the application content included in the message payload.)54
192 Q -.15(Fo)5 G 2.5(rs).15 G(enders emplo)-2.5 E
(ying systematic FEC encoding, these \214elds)-.1 E
(correspond to actual length and of)54 204 Q(fset v)-.25 E
(alues for the payload of messages which contain original data content.)
-.25 E -.15(Fo)5 G(r).15 E F1(NORM_DATA)54 216 Q F0(messages containing\
 calculated parity content, these \214elds will actually contain v)2.5 E
(alues computed by FEC)-.25 E
(encoding of the "payload_len" and "payload_of)54 228 Q(fset" v)-.25 E
(alues of the)-.25 E F1(NORM_DATA)2.5 E F0(data se)2.5 E
(gments of the corresponding FEC)-.15 E(coding block.)54 240 Q
(Thus, the "payload_len" and "payload_of)5 E(fset" v)-.25 E
(alues of missing data content can be determined when)-.25 E
(decoding an FEC coding block.)54 252 Q
(Note that these \214elds are present in)5 E F1(NORM_DATA)2.5 E F0
(messages only when small block,)2.5 E(systematic FEC encoding is used.)
54 264 Q(Also, these \214elds do _not_ contrib)5 E(ute to the v)-.2 E
(alue of the)-.25 E F1(NORM_DATA)2.5 E F0("hdr_len" \214eld.)2.5 E(The \
"payload_data" \214eld contains the original application data or comput\
ed parity content associated with the se)54 288 Q 2.5(gment. The)-.15 F
(maximum length of this \214eld SHALL be limited to a maximum of the se\
nder')54 300 Q(s)-.55 E F2(NormSe)2.5 E(gmentSize)-.4 E F0(as gi)2.5 E
-.15(ve)-.25 G 2.5(ni).15 G 2.5(nt)-2.5 G(he FTI for the)-2.5 E 2.5
(object. The)54 312 R
(length of this \214eld for messages containing parity content will al)
2.5 E -.1(wa)-.1 G(ys be of length).1 E F2(NormSe)2.5 E(gmentSize)-.4 E
F0 5(.W)C(hen)-5 E(encoding data se)54 324 Q(gments of v)-.15 E
(arying sizes, the FEC encoder SHALL assume ZER)-.25 E 2.5(Ov)-.4 G
(alue padding for data se)-2.75 E(gments with)-.15 E
(length less than the)54 336 Q F2(NormSe)2.5 E(gmentSize)-.4 E F0 5(.W)C
(hen applicable, the recei)-5 E -.15(ve)-.25 G 2.5(rM).15 G 2.1 -1.05
(AY u)-2.5 H(se the "payload_len" information to properly)1.05 E(retrie)
54 348 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 2.5(As)5 G(ender')-2.5 E(s)-.55 E
F2(NormSe)2.5 E(gmentSize)-.4 E F0(SHOULD generally be constant)2.5 E
(for the duration of a gi)54 360 Q -.15(ve)-.25 G 2.5(ns).15 G(ender')
-2.5 E 2.5(st)-.55 G(erm of participation in the session, b)-2.5 E
(ut may possibly v)-.2 E(ary on a per)-.25 E(-object basis.)-.2 E(The)5
E F2(NormSe)54 372 Q(gmentSize)-.4 E F0(is e)2.5 E(xpected to be con\
\214gurable by the sender application 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 possibly le).15 E -.15(ve)-.25 G(raged).15 E
(at session startup to perform this con\214guration.)54 396 Q/F3 10
/Times-Bold@0 SF(4.2.2 NORM_INFO Message)54 420 Q F0(The)54 444 Q F1
(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)54 456 Q F2(NormObjects)2.5 E F0
5(.A)C 2.5(ne)-5 G(xample)-2.65 E F1(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)54 468 Q F1
(NORM_INFO)2.5 E F0 2.5(payload. Recei)2.5 F -.15(ve)-.25 G
(rs may use the).15 E F1(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.)54 480 Q(Each)5 E F2(NormObject)2.5 E F0(can ha)2.5 E
.3 -.15(ve a)-.2 H 2.5(ni).15 G(ndependent)-2.5 E(unit of)54 492 Q F1
(NORM_INFO)2.5 E F0(associated with it.)2.5 E F1(NORM_DATA)5 E F0
(messages contain a \215ag to indicate the a)2.5 E -.25(va)-.2 G
(ilability of).25 E F1(NORM_INFO)2.5 E F0(for a gi)54 504 Q -.15(ve)-.25
G(n).15 E F2(NormObject)2.5 E F0 5(.N)C(ORM recei)-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 F1
(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)54 516 Q
-.15(ve)-.25 G(n).15 E F2(NormObject)2.5 E F0 5(.T)C(he size of the)-5 E
F1(NORM_INFO)2.5 E F0(content is limited to that of a single)2.5 E F2
(NormSe)2.5 E(gmentSize)-.4 E F0(for the gi)2.5 E -.15(ve)-.25 G(n).15 E
(sender)54 528 Q 5(.T)-.55 G(his atomic nature allo)-5 E(ws the)-.25 E
F1(NORM_INFO)2.5 E F0(to be rapidly and ef)2.5 E
(\214ciently repaired within the NORM reliable)-.25 E
(transmission process.)54 540 Q(When)54 564 Q F1(NORM_INFO)2.5 E F0
(content is a)2.5 E -.25(va)-.2 G(ilable for a).25 E F2(NormObject)2.5 E
F0 2.5(,t)C(he NORM_FLA)-2.5 E(G_INFO \215ag SHALL be set in)-.4 E F1
(NORM_DATA)2.5 E F0
(messages for the corresponding "object_transport_id" and the)54 576 Q
F1(NORM_INFO)2.5 E F0
(message shall be transmitted as the \214rst message)2.5 E(for the)54
588 Q F2(NormObject)2.5 E F0(.)A(Adamson, Bormann, 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
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)127.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q(|version| type=1|)109.2 120 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 162(|s)109.2 144 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 60(|s)109.2 168 S 60(ession_id |)-60 F 30(grtt |)30 F 24(gsize |)
30 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 180 Q 30(|f)109.2 192 S 24(lags | fec_id)-30 F 30(|o)24 G 36
(bject_transport_id |)-30 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 96(|h)109.2 216 S(eader_extensions \(if applicable\))-96 E(|)84 E
180(|.)109.2 228 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
240 Q 150(|p)109.2 252 S 150(ayload_data |)-150 F 180(|.)109.2 264 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
276 Q/F2 10/Times-Italic@0 SF(NORM_INFO Messa)241.5 300 Q .2 -.1(ge F)
-.1 H(ormat)-.95 E F0(The "v)54 324 Q(ersion", "type","hdr_len", "seque\
nce", and "source_id" \214elds form the NORM Common Message Header as d\
escribed)-.15 E(in Section 4.1.)54 336 Q(The v)5 E
(alue of "hdr_len" \214eld when no header e)-.25 E
(xtensions are present is 4.)-.15 E(The "session_id", "grtt", "gsize", \
"\215ags", "fec_id", and "object_transport_id" \214elds carry the same \
information and serv)54 360 Q 2.5(et)-.15 G(he)-2.5 E
(same purpose as with)54 372 Q F1(NORM_DATA)2.5 E F0 2.5
(messages. These)2.5 F -.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)-.25 E
(further transmissions from the sender when)54 384 Q F1(NORM_INFO)2.5 E
F0(is the \214rst message recei)2.5 E -.15(ve)-.25 G(d.).15 E(As with)54
408 Q F1(NORM_DATA)2.5 E F0
(messages, the NORM FTI Header Extension may be optionally applied to)
2.5 E F1(NORM_INFO)2.5 E F0(messages.)2.5 E 1.6 -.8(To c)54 420 T
(onserv).8 E 2.5(ep)-.15 G(rotocol o)-2.5 E -.15(ve)-.15 G(rhead, some \
NORM implementations may wish to apply the FTI Header Extension when us\
ed to).15 E F1(NORM_INFO)54 432 Q F0(messages only)2.5 E(.)-.65 E(The)54
456 Q F1(NORM_INFO)2.5 E F0("payload_data" \214eld contains sender appl\
ication-de\214ned content which can be used by recei)2.5 E -.15(ve)-.25
G(r).15 E(applications for v)54 468 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)54 492 Q F1(NORM_CMD)54 516 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)54 528 Q -.15(ve)-.25 G 2.5(rr).15 G(epair)-2.5 E
("windo)54 540 Q(ws", and noti\214cation of sender status.)-.25 E 2.5
(Ac)5 G(ore set of)-2.5 E F1(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)54 552 Q -.25(va)-.2 G
(ilable for potential application-speci\214c use.).25 E(Some)5 E F1
(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)54 564 R 2.5(ya)-.15 G
(ttached content will be limited to maximum length of the sender)-2.5 E
F2(NormSe)2.5 E(gmentSize)-.4 E F0(to retain the atomic)2.5 E
(nature of commands.)54 576 Q(All)5 E F1(NORM_CMD)2.5 E F0(messages be)
2.5 E
(gin with a common set of \214elds, after the usual NORM message common)
-.15 E(header)54 588 Q 5(.T)-.55 G(he standard)-5 E F1(NORM_CMD)2.5 E F0
(\214elds are:)2.5 E(Adamson, Bormann, 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
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q(|version| type=3|)109.2 120 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 162(|s)109.2 144 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 60(|s)109.2 168 S 60(ession_id |)-60 F 30(grtt |)30 F 24(gsize |)
30 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 180 Q 30(|f)109.2 192 S 18(lavor |)-30 F(|)282 E 42
(+-+-+-+-+-+-+-+-+ NORM_CMD)109.2 204 R 132(Content +)6 F 180(|.)109.2
216 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
228 Q/F2 10/Times-Italic@0 SF(NORM_CMD Standar)243.5 252 Q 2.5(dF)-.37 G
(ields)-2.95 E F0(The "v)54 276 Q(ersion", "type", "hdr_len", "sequence\
", and "source_id" \214elds form the NORM Common Message Header as)-.15
E(described in Section 4.1.)54 288 Q(The v)5 E
(alue of the "hdr_len" \214eld for)-.25 E F1(NORM_CMD)2.5 E F0
(messages without header e)2.5 E(xtensions present)-.15 E
(depends upon the "\215a)54 300 Q -.2(vo)-.2 G(r" \214eld.).2 E
(The "session_id", "grtt" and "gsize" \214elds pro)54 324 Q
(vide the same information and serv)-.15 E 2.5(et)-.15 G
(he same purpose as with)-2.5 E F1(NORM_DATA)2.5 E F0(and)54 336 Q F1
(NORM_INFO)2.5 E 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 F1(NORM_CMD)2.5 E F0
(message is dependent upon the command type \("\215a)54 348 Q -.2(vo)-.2
G 2.5(r"\). NORM).2 F(command \215a)2.5 E -.2(vo)-.2 G(rs include:).2 E
.4 LW 529.69 370.5 78.71 370.5 DL 54.665(Command Fla)125.875 380 R -.2
(vo)-.2 G 2.5(rV).2 G 109.64(alue Purpose)-3.61 F 529.69 384.5 78.71
384.5 DL F1(NORM_CMD\(FLUSH\))83.71 394 Q F0(1)73.99 E
(Used to indicate sender temporary end-of-transmission.)290.69 394 Q
(\(Assists in rob)290.69 406 Q
(ustly initiating outstanding repair requests)-.2 E(from recei)290.69
418 Q -.15(ve)-.25 G 2.5(rs\). May).15 F
(also be optionally used to collect)2.5 E(positi)290.69 430 Q .3 -.15
(ve a)-.25 H(ckno).15 E(wledgement of reliable reception from)-.25 E
(subset of recei)290.69 442 Q -.15(ve)-.25 G(rs.).15 E 529.69 446.5
78.71 446.5 DL F1(NORM_CMD\(EOT\))83.71 456 Q F0(2)85.99 E
(Used to indicate sender permanent end-of-transmission.)290.69 456 Q
529.69 460.5 78.71 460.5 DL F1(NORM_CMD\(SQUELCH\))83.71 470 Q F0(3)
61.99 E(Used to adv)290.69 470 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)290.69 482 Q -.4(AC)-.35 G(Ks from recei).4
E -.15(ve)-.25 G(rs.).15 E 529.69 486.5 78.71 486.5 DL F1
(NORM_CMD\(CC\))83.71 496 Q F0(4)91.99 E(Used for GR)290.69 496 Q
(TT measurement and collection of)-.6 E(congestion control feedback.)
290.69 508 Q 529.69 512.5 78.71 512.5 DL F1(NORM_CMD\(REPAIR_ADV\))83.71
522 Q F0(5)43.99 E(Used to adv)290.69 522 Q(ertise sender')-.15 E 2.5
(sa)-.55 G(ggre)-2.5 E -.05(ga)-.15 G(ted repair/feedback).05 E
(state for suppression of unicast feedback from recei)290.69 534 Q -.15
(ve)-.25 G(rs.).15 E 529.69 538.5 78.71 538.5 DL F1(NORM_CMD\(ACK_REQ\))
83.71 548 Q F0(6)61.99 E(Used to request application-de\214ned positi)
290.69 548 Q -.15(ve)-.25 G(ackno)290.69 560 Q
(wledgement from a list of recei)-.25 E -.15(ve)-.25 G(rs \(OPTION).15 E
(AL\).)-.35 E 529.69 564.5 78.71 564.5 DL F1(NORM_CMD\(APPLICATION\))
83.71 574 Q F0(7)37.99 E
(Used for application-de\214ned purposes which may need to)290.69 574 Q
(temporarily preempt data transmission \(OPTION)290.69 586 Q(AL\).)-.35
E 529.69 590.5 78.71 590.5 DL 529.69 370.5 529.69 590.5 DL 78.71 370.5
78.71 590.5 DL 283.19 370.5 283.19 590.5 DL 217.21 370.5 217.21 590.5 DL
/F3 10/Times-BoldItalic@0 SF(NORM_CMD\(FLUSH\) Message)54 616 Q F0(The)
54 640 Q F1(NORM_CMD\(FLUSH\))2.5 E F0(command is sent when the sender \
reaches the end of all data content and pending repairs it has)2.5 E
(queued for transmission.)54 652 Q
(This may indicate a temporary or permanent end of data transmission, b)
5 E(ut the sender is still willing)-.2 E(Adamson, Bormann, et al.)36 696
Q(Expires December 2003)105.89 E([P)119.09 E(age 17])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(to respond to repair requests.)54 84 Q
(This command is repeated once per)5 E/F1 10/Courier@0 SF(2*GRTT)2.5 E
F0(to e)2.5 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)-2.5 E(repair requests up to\
 and including the transmission point indicated within the)54 96 Q F1
(NORM_CMD\(FLUSH\))2.5 E F0 2.5(message. The)2.5 F(number)2.5 E
(of repeats is equal to)54 108 Q F1(NORM_ROBUST_FACTOR)2.5 E F0
(unless a list of recei)2.5 E -.15(ve)-.25 G(rs from which e).15 E
(xplicit positi)-.15 E .3 -.15(ve a)-.25 H(ckno).15 E(wledgement)-.25 E
(\("acking_node_list"\) is gi)54 120 Q -.15(ve)-.25 G 2.5(n. In).15 F
(that case, the "acking_node_list" is updated as ackno)2.5 E
(wledgements are recei)-.25 E -.15(ve)-.25 G 2.5(da).15 G(nd the)-2.5 E
F1(NORM_CMD\(FLUSH\))54 132 Q F0
(is repeated according to the mechanism described in Section 5.5.3.)2.5
E(The greater the)5 E F1(NORM_ROBUST_FACTOR)54 144 Q F0 2.5(,t)C
(he greater the probability that all applicable recei)-2.5 E -.15(ve)
-.25 G(rs will be e).15 E(xcited for ackno)-.15 E(wledgement or)-.25 E
(repair requests \(N)54 156 Q -.4(AC)-.35 G
(Ks\) _and_ that the corresponding N).4 E -.4(AC)-.35 G(Ks are deli).4 E
-.15(ve)-.25 G(red to the sender).15 E 5(.I)-.55 G 2.5(fa)-5 G F1
(NORM_NACK)A F0(message)2.5 E(interrupts the \215ush process, the sende\
r will re-initiate the \215ush process after an)54 168 Q 2.5(yr)-.15 G
(esulting repair transmissions are)-2.5 E(completed.)54 180 Q
(Note that recei)54 204 Q -.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 \(if there are outstanding repair needs\) when).4 E
(no messages of an)54 216 Q 2.5(yt)-.15 G(ype are recei)-2.5 E -.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 F1(2*GRTT*NORM_ROBUST_FACTOR)54 228 Q
F0(and will be discussed more later)2.5 E 5(.W)-.55 G(ith a suf)-5.4 E
(\214cient)-.25 E F1(NORM_ROBUST_FACTOR)2.5 E F0 -.25(va)2.5 G(lue,).25
E(data content is deli)54 240 Q -.15(ve)-.25 G
(red with a high assurance of reliability).15 E 5(.T)-.65 G
(he penalty of a lar)-5 E(ge)-.18 E F1(NORM_ROBUST_FACTOR)2.5 E F0 -.25
(va)2.5 G(lue is).25 E(potentially e)54 252 Q(xcess sender)-.15 E F1
(NORM_CMD\(FLUSH\))2.5 E F0
(transmissions and a longer timeout for recei)2.5 E -.15(ve)-.25 G
(rs to self-initiate the terminal).15 E -.35(NA)54 264 S(CK process.)
-.05 E -.15(Fo)54 288 S 2.5<728c>.15 G
(nite-size transport objects such as)-2.5 E F1(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 \(if there are)-2.5 E
(no further pending objects\) occurs at the end of these objects.)54 300
Q(Thus, FEC repair information is al)5 E -.1(wa)-.1 G(ys a).1 E -.25(va)
-.2 G(ilable for repairs).25 E
(in response to repair requests elicited by the \215ush command.)54 312
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 occur)-2.5 E(at an)
54 324 Q 2.5(yt)-.15 G(ime, including in the middle of an FEC coding bl\
ock if systematic FEC codes are emplo)-2.5 E 2.5(yed. In)-.1 F
(this case, the sender)2.5 E(will not yet be able to pro)54 336 Q(vide \
FEC parity content as repair for the concurrent coding block and will b\
e limited to e)-.15 E(xplicitly)-.15 E
(repairing stream data content for that block.)54 348 Q(Applications th\
at anticipate frequent \215ushing of stream content SHOULD be)5 E(judic\
ious in the selection of the FEC coding block size \(i.e., do not use a\
 v)54 360 Q(ery lar)-.15 E(ge coding block size if frequent \215ushing)
-.18 E 2.5(occurs\). F)54 372 R(or e)-.15 E(xample, a reliable multicas\
t application transmitting an on-going series of intermittent, relati)
-.15 E -.15(ve)-.25 G(ly small).15 E
(messaging content will need to trade-of)54 384 Q 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)2.5 E F0
(paradigm with an appropriate FEC coding block size.)54 396 Q
(This is analogous to application trade-of)5 E(fs for other transport)
-.25 E(protocols such as the selection of dif)54 408 Q
(ferent TCP modes of operation such as "no delay", etc.)-.25 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 E(age 18])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q(|version| type=3|)109.2 120 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 162(|s)109.2 144 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 66(|s)109.2 168 S 54(ession_id |)-66 F 24(grtt | gsize |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
180 Q 18(|f)109.2 192 S(lavor = 1)-18 E 24(|f)12 G 24(ec_id |)-24 F 30
(object_transport_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 150(|f)109.2 216 S 138(ec_payload_id |)-150 F 180(|.)109.2 228 S
174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
240 Q 96(|a)109.2 252 S(cking_node_list \(if applicable\))-96 E(|)90 E
180(|.)109.2 264 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
276 Q/F2 10/Times-Italic@0 SF(NORM_CMD\(FLUSH\) Messa)223.17 300 Q .2
-.1(ge F)-.1 H(ormat)-.95 E F0
(In addition to the NORM common message header and standard)54 324 Q F1
(NORM_CMD)2.5 E F0(\214elds, the)2.5 E F1(NORM_CMD\(FLUSH\))2.5 E F0
(message)2.5 E(contains \214elds to identify the current status and log\
ical transmit position of the sender)54 336 Q(.)-.55 E(The "fec_id" \
\214eld indicates the FEC type used for the \215ushing "object_transpor\
t_id" and implies the size and format of the)54 360 Q
("fec_payload_is" \214eld.)54 372 Q(Note the "hdr_len" v)5 E
(alue for the)-.25 E F1(NORM_CMD\(FLUSH\))2.5 E F0
(message is 4 plus the size of the)2.5 E
("fec_payload_id" \214eld when no header e)54 384 Q
(xtensions are present.)-.15 E(The "object_transport_id" and "fec_paylo\
ad_id" \214elds indicate the sender')54 408 Q 2.5(sc)-.55 G
(urrent logical "transmit position".)-2.5 E(These \214elds)5 E
(are interpreted in the same manner as in the)54 420 Q F1(NORM_DATA)2.5
E F0(message type.)2.5 E(Upon receipt of the the)5 E F1
(NORM_CMD\(FLUSH\))2.5 E F0(,)A(recei)54 432 Q -.15(ve)-.25 G(rs are e)
.15 E(xpected to check their completion state _through_ \(including\) t\
his transmission position.)-.15 E(If recei)5 E -.15(ve)-.25 G(rs ha).15
E -.15(ve)-.2 G(outstanding repair needs in this range, the)54 444 Q 2.5
(yS)-.15 G(HALL initiate the NORM N)-2.5 E -.4(AC)-.35 G 2.5(KR).4 G
(epair Process as described in Section 5.3.)-2.5 E(If)5 E(recei)54 456 Q
-.15(ve)-.25 G(rs ha).15 E .3 -.15(ve n)-.2 H 2.5(oo).15 G
(utstanding repair needs, no response to the)-2.5 E F1
(NORM_CMD\(FLUSH\))2.5 E F0(is generated.)2.5 E -.15(Fo)54 480 S(r).15 E
F1(NORM_OBJECT_STREAM)2.5 E F0
(objects using systematic FEC codes, recei)2.5 E -.15(ve)-.25 G
(rs MUST request "e).15 E(xplicit-only" repair of the)-.15 E
(identi\214ed "source_block_number" if the gi)54 492 Q -.15(ve)-.25 G
2.5(n").15 G(encoding_symbol_id" is less than the "source_block_len".)
-2.5 E(This condition)5 E(indicates the sender has not yet completed en\
coding the corresponding FEC block and parity content is not yet a)54
504 Q -.25(va)-.2 G 2.5(ilable. An).25 F("e)54 516 Q
(xplicit-only" repair request consists of N)-.15 E -.4(AC)-.35 G 2.5(Kc)
.4 G
(ontent for the applicable "source_block_number" which does not include)
-2.5 E(an)54 528 Q 2.5(yr)-.15 G(equests for parity-based repair)-2.5 E
5(.T)-.55 G(his allo)-5 E(ws NORM sender applications to "\215ush" an o\
ngoing stream of transmission)-.25 E(when needed, e)54 540 Q -.15(ve)
-.25 G 2.5(ni).15 G 2.5(fi)-2.5 G 2.5(nt)-2.5 G
(he middle of an FEC block.)-2.5 E
(Once the sender resumes stream transmission and passes the end of the)5
E(pending coding block, subsequent N)54 552 Q -.4(AC)-.35 G
(Ks from recei).4 E -.15(ve)-.25 G
(rs SHALL request parity-based repair as usual.).15 E
(Note that the use of)5 E 2.5(as)54 564 S
(ystematic FEC code is assumed here.)-2.5 E(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)-2.5 E
(5.3.)54 576 Q(The OPTION)54 600 Q
(AL "acking_node_list" \214eld contains a list of)-.35 E F2(NormNodeIds)
2.5 E F0(for recei)2.5 E -.15(ve)-.25 G
(rs from which the sender is requesting).15 E -.15(ex)54 612 S
(plicit positi).15 E .3 -.15(ve a)-.25 H(ckno).15 E(wledgement of recep\
tion up through the transmission point identi\214ed by the "object_tran\
sport_id" and)-.25 E("fec_payload_id" \214elds.)54 624 Q
(The length of the list can be inferred from the length of the recei)5 E
-.15(ve)-.25 G(d).15 E F1(NORM_CMD\(FLUSH\))2.5 E F0 2.5(message. When)
54 636 R(the "acking_node_list" is present, the lightweight positi)2.5 E
.3 -.15(ve a)-.25 H(ckno).15 E(wledgement process described in Section)
-.25 E(5.5.3 SHALL be observ)54 648 Q(ed.)-.15 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 E(age 19])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Times-BoldItalic@0 SF(NORM_CMD\(EO)54 84 Q
(T\) Message)-.4 E F0(The)54 108 Q/F2 10/Courier@0 SF(NORM_CMD\(EOT\))
2.5 E F0(command is sent when the sender reaches permanent end-of-trans\
mission with respect to the)2.5 E/F3 10/Times-Italic@0 SF(NormSession)54
120 Q F0(and will not respond to further repair requests.)2.5 E
(This allo)5 E(ws recei)-.25 E -.15(ve)-.25 G
(rs to gracefully reach closure of operation).15 E
(with this sender \(without requiring an)54 132 Q 2.5(yt)-.15 G
(imeout\) and free an)-2.5 E 2.5(yr)-.15 G
(esources that are no longer needed.)-2.5 E F2 114(0123)124.2 156 S 6
(01234567890123456789012345678901)118.2 168 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
180 Q(|version| type=3|)109.2 192 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 162(|s)109.2 216 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
228 Q 60(|s)109.2 240 S 60(ession_id |)-60 F 30(grtt |)30 F 24(gsize |)
30 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 252 Q 18(|f)109.2 264 S(lavor = 2)-18 E 120(|r)12 G 108(eserved |)
-120 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
276 Q F3(NORM_CMD\(EO)229.48 300 Q(T\) Messa)-.4 E .2 -.1(ge F)-.1 H
(ormat)-.95 E F0(The v)54 324 Q(alue of the "hdr_len" \214eld for)-.25 E
F2(NORM_CMD\(EOT\))2.5 E F0(messages without header e)2.5 E
(xtensions present is 4.)-.15 E(The "reserv)5 E(ed")-.15 E
(\214eld is reserv)54 336 Q
(ed for future use and MUST be set to an all ZER)-.15 E 2.5(Ov)-.4 G 2.5
(alue. Recei)-2.75 F -.15(ve)-.25 G(rs MUST ignore the "reserv).15 E
(ed" \214eld.)-.15 E F1(NORM_CMD\(SQ)54 360 Q(UELCH\) Message)-.1 E F0
(The)54 384 Q F2(NORM_CMD\(SQUELCH\))2.5 E F0
(command is transmitted in response to outdated or in)2.5 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(y)-2.5 E(the sender)54 396 Q 5(.I)-.55 G -1.95 -.4(nv a)-5 H
(lid).4 E F2(NORM_NACK)2.5 E F0(content consists of repair requests for)
2.5 E F3(NormObjects)2.5 E F0(for which the sender is unable or)2.5 E
(unwilling to pro)54 408 Q(vide repair)-.15 E 5(.T)-.55 G(his includes \
repair requests for outdated objects, aborted objects, or those objects\
 which the)-5 E(sender pre)54 420 Q(viously transmitted mark)-.25 E
(ed with the)-.1 E F2(NORM_FLAG_UNRELIABLE)2.5 E F0 2.5(\215ag. This)2.5
F(command indicates to recei)2.5 E -.15(ve)-.25 G(rs).15 E
(what content is a)54 432 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).15 E
(not generate repair requests for content identi\214ed as in)54 444 Q
-.25(va)-.4 G(lid by a).25 E F2(NORM_CMD\(SQUELCH\))2.5 E F0(.)A(The)54
468 Q F2(NORM_CMD\(SQUELCH\))2.5 E F0(command is sent once per)2.5 E F2
(2*GRTT)2.5 E F0(at the most.)2.5 E(The)5 E F2(NORM_CMD\(SQUELCH\))2.5 E
F0(adv)2.5 E(ertises the)-.15 E(current "repair windo)54 480 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
492 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 speci\214c pre)54 504 Q
(viously enqueued objects.)-.25 E(The list also)5 E
(contains the identi\214ers for an)54 516 Q 2.5(yo)-.15 G
(bjects within the repair windo)-2.5 E 2.5(wt)-.25 G
(hat were sent with the)-2.5 E F2(NORM_FLAG_UNRELIABLE)2.5 E F0(\215ag)
2.5 E 2.5(set. In)54 528 R(normal conditions, it is e)2.5 E(xpected the)
-.15 E F2(NORM_CMD\(SQUELCH\))2.5 E F0(will be needed infrequently)2.5 E
2.5(,a)-.65 G(nd generally only to)-2.5 E(pro)54 540 Q
(vide a reference repair windo)-.15 E 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)-.15 E
(netw)54 552 Q(ork conditions.)-.1 E(The starting point of the in)54 576
Q -.25(va)-.4 G(lid).25 E F3(NormObject)2.5 E F0(list be)2.5 E
(gins with the lo)-.15 E(west in)-.25 E -.25(va)-.4 G(lid).25 E F3
(NormT)2.5 E -.15(ra)-.55 G(nsportId).15 E F0(greater than the current)
2.5 E("repair windo)54 588 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')54 600 Q(s)-.55 E
F3(NormSe)2.5 E(gmentSize)-.4 E F0 5(.T)C(his allo)-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)54 612 Q 2.5(ww)-.25 G
(ith minimal transmission of)-2.5 E F2(NORM_CMD\(SQUELCH\))2.5 E F0 2.5
(commands. The)2.5 F(format of the)2.5 E F2(NORM_CMD\(SQUELCH\))2.5 E F0
(message is:)54 624 Q(Adamson, Bormann, et al.)36 696 Q
(Expires December 2003)105.89 E([P)119.09 E(age 20])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q 24(|v)109.2 120 S 18(ersion |)-24 F(type = 3)18 E 60(|s)24 G 72
(equence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 162(|s)109.2 144 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 60(|s)109.2 168 S 60(ession_id |)-60 F 30(grtt |)30 F 24(gsize |)
30 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 180 Q 12(|f)109.2 192 S(lavor = 3)-12 E 30(|f)18 G 18(ec_id |)-30
F 30(object_transport_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 150(|f)109.2 216 S 138(ec_payload_id |)-150 F 180(|.)109.2 228 S
174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
240 Q 144(|i)109.2 252 S 114(nvalid_object_list |)-144 F 180(|.)109.2
264 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
276 Q/F2 10/Times-Italic@0 SF(NORM_CMD\(SQ)216.275 300 Q(UELCH\) Messa)
-.1 E .2 -.1(ge F)-.1 H(ormat)-.95 E F0
(In addition to the NORM common message header and standard)54 324 Q F1
(NORM_CMD)2.5 E F0(\214elds, the)2.5 E F1(NORM_CMD\(SQUELCH\))2.5 E F0
(message)2.5 E(contains \214elds to identify the earliest logical trans\
mit position of the sender')54 336 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)54 348 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.)54 360
Q(The "object_transport_id" and "fec_payload_id" \214elds are concatena\
ted to indicate the be)54 384 Q(ginning of the sender')-.15 E 2.5(sc)
-.55 G(urrent)-2.5 E(repair windo)54 396 Q 2.5(w\()-.25 G(i.e., the log\
ically earliest point in its transmission history for which the sender \
can pro)-2.5 E(vide repair\).)-.15 E(The)5 E("fec_id" \214eld implies t\
he size and format of the "fec_payload_id" \214eld.)54 408 Q(This serv)5
E(es as an adv)-.15 E(ertisement of a)-.15 E
("synchronization point" for recei)54 420 Q -.15(ve)-.25 G
(rs to request repair).15 E 5(.N)-.55 G
(ote, that while an "encoding_symbol_id" may be included in the)-5 E
("fec_payload_id" \214eld, the sender')54 432 Q 2.5(sr)-.55 G
(epair windo)-2.5 E 2.5(wS)-.25 G
(HOULD be aligned on FEC coding block boundaries and thus the)-2.5 E
("encoding_symbol_id" SHOULD be zero.)54 444 Q(The "in)54 468 Q -.25(va)
-.4 G(lid_object_list" is a list of 16-bit).25 E F2(NormT)2.5 E -.15(ra)
-.55 G(nsportIds).15 E F0(that, although the)2.5 E 2.5(ya)-.15 G
(re within the range of the sender')-2.5 E 2.5(sc)-.55 G(urrent)-2.5 E
(repair windo)54 480 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-)-.15 E
(date object e)54 492 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 can be).25 E(determined from the pack)54
504 Q(et')-.1 E 2.5(sp)-.55 G
(ayload length and is limited to a maximum of the)-2.5 E F2(NormSe)2.5 E
(gmentSize)-.4 E F0(of the sender)2.5 E 5(.T)-.55 G(hus, for)-5 E -.15
(ve)54 516 S(ry lar).15 E(ge repair windo)-.18 E
(ws, it is possible that a single)-.25 E F1(NORM_CMD\(SQUELCH\))2.5 E F0
(message may not be capable of listing the)2.5 E(entire set of in)54 528
Q -.25(va)-.4 G(lid objects in the repair windo).25 E 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)-.15 E F2(NormObjectId)54 540 Q F0
(that is greater than or equal to the lo)2.5 E(west ordinal in)-.25 E
-.25(va)-.4 G(lid).25 E F2(NormObjectId)2.5 E F0(from the N)2.5 E -.4
(AC)-.35 G 2.5(Km).4 G(essage\(s\) that)-2.5 E(prompted the)54 552 Q F1
(NORM_CMD\(SQUELCH\))2.5 E F0 2.5(generation. The)2.5 F F2
(NormObjectIds)2.5 E F0(in the "in)2.5 E -.25(va)-.4 G
(lid_object_list" MUST be greater than).25 E
(the "object_transport_id" marking the be)54 564 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)54 576 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')54 588 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)54 600 Q -.25(va)-.4 G(l\
idate \(i.e. dequeue\) portions of enqueued content \(e.g., certain obj\
ects\) for which it no longer wishes to pro).25 E(vide reliable)-.15 E
(transport.)54 612 Q(Adamson, Bormann, 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
(June 2003)185.175 E/F1 10/Times-BoldItalic@0 SF(NORM_CMD\(CC\) Message)
54 84 Q F0(The)54 108 Q/F2 10/Courier@0 SF(NORM_CMD\(CC\))2.5 E F0
(messages contains \214elds to enable sender)2.5 E(->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 to e)54 120 Q
(xcite the group for congestion control feedback.)-.15 E 2.5(Ab)5 G
(aseline NORM congestion control scheme)-2.5 E(\(NORM-CC\), based on th\
e TCP-Friendly Multicast Congestion Control \(TFMCC\) Building Block [1\
8] is described in)54 132 Q(Section 5.5.2 of this document.)54 144 Q
(The)5 E F2(NORM_CMD\(CC\))2.5 E F0
(message is usually transmitted as part of NORM-CC congestion)2.5 E
(control operation.)54 156 Q 2.5(AN)5 G(ORM header e)-2.5 E
(xtension is de\214ned belo)-.15 E 2.5(wt)-.25 G 2.5(ob)-2.5 G 2.5(eu)
-2.5 G(sed with the)-2.5 E F2(NORM_CMD\(CC\))2.5 E F0
(message to support)2.5 E(NORM-CC operation.)54 168 Q(Dif)5 E
(ferent header e)-.25 E(xtensions may be de\214ned for the)-.15 E F2
(NORM_CMD\(CC\))2.5 E F0(\(and/or other NORM messages)2.5 E
(as needed\) to support alternati)54 180 Q .3 -.15(ve c)-.25 H
(ongestion control schemes in the future.).15 E
(If NORM is operated in a pri)5 E -.25(va)-.25 G(te netw).25 E(ork with)
-.1 E(congestion control operation disabled, the)54 192 Q F2
(NORM_CMD\(CC\))2.5 E F0(message is then used for GR)2.5 E
(TT measurement only and may)-.6 E(optionally be sent less frequently t\
han with congestion control operation.)54 204 Q F2 114(0123)124.2 228 S
6(01234567890123456789012345678901)118.2 240 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
252 Q(|version| type=3|)109.2 264 Q 18(hdr_len |)24 F 60(sequence |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
276 Q 162(|s)109.2 288 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
300 Q 66(|s)109.2 312 S 54(ession_id |)-66 F 24(grtt | gsize |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
324 Q 18(|f)109.2 336 S(lavor = 4)-18 E 24(|r)12 G 12(eserved |)-24 F 54
(cc_sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
348 Q 150(|s)109.2 360 S 144(end_time_sec |)-150 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
372 Q 144(|s)109.2 384 S 144(end_time_usec |)-144 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
396 Q 90(|h)109.2 408 S(eader extensions \(if applicable\))-90 E(|)90 E
180(|.)109.2 420 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
432 Q 108(|c)109.2 444 S(c_node_list \(if applicable\))-108 E(|)102 E
180(|.)109.2 456 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
468 Q/F3 10/Times-Italic@0 SF(NORM_CMD\(CC\) Messa)232.055 492 Q .2 -.1
(ge F)-.1 H(ormat)-.95 E F0(The NORM common message header and standard)
54 516 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 "reserv)54 540 Q(ed" \214eld is for po\
tential future use and should be set to zero in this v)-.15 E
(ersion of the NORM protocol.)-.15 E
(The "cc_sequence" \214eld is a sequence number applied by the sender)54
564 Q 5(.F)-.55 G(or NORM-CC operation, it is used to pro)-5.15 E(vide)
-.15 E(functionality equi)54 576 Q -.25(va)-.25 G
(lent to the "feedback round number" \().25 E F2(fb_nr)A F0
(\)described in the TFMCC Building Block document [18].)A
(The most recently recei)54 588 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 can be fed back to the sender in congestion).15 E
(control feedback generated by the recei)54 600 Q -.15(ve)-.25 G
(rs for that sender).15 E 5(.T)-.55 G
(he "cc_sequence" number can also be used in NORM)-5 E
(implementations to assess ho)54 612 Q 2.5(wr)-.25 G(ecently a recei)
-2.5 E -.15(ve)-.25 G 2.5(rh).15 G(as recei)-2.5 E -.15(ve)-.25 G(d).15
E F2(NORM_CMD\(CC\))2.5 E F0(probes from the sender)2.5 E 5(.T)-.55 G
(his can be useful)-5 E(instrumentation for comple)54 624 Q 2.5(xo)-.15
G 2.5(re)-2.5 G(xperimental multicast routing en)-2.65 E(vironments.)-.4
E(The "send_time" \214eld is a timestamp indicating the time that the)54
648 Q F2(NORM_CMD\(CC\))2.5 E F0(message w)2.5 E(as transmitted.)-.1 E
(This consists)5 E(Adamson, Bormann, 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
(June 2003)185.175 E(of a 64-bit \214eld containing 32-bits with the ti\
me in seconds \("sent_time_sec"\) and 32-bits with the time in microsec\
onds)54 84 Q(\("send_time_usec"\) since some reference time the source \
maintains \(usually 00:00:00, 1 January 1970\).)54 96 Q
(The byte ordering)5 E(of the \214elds is "Big Endian" netw)54 108 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 the time).15
E(the)54 120 Q 2.5(yr)-.15 G(ecei)-2.5 E -.15(ve)-.25 G 2.5(dt).15 G(he)
-2.5 E/F1 10/Courier@0 SF(NORM_CMD\(CC\))2.5 E F0(message to the time o\
f their response as the "grtt_response" portion of)2.5 E F1(NORM_ACK)2.5
E F0(and)2.5 E F1(NORM_NACK)54 132 Q F0(messages generated.)2.5 E
(This allo)5 E(ws the sender to e)-.25 E -.25(va)-.25 G
(luate round-trip times to dif).25 E(ferent recei)-.25 E -.15(ve)-.25 G
(rs for congestion).15 E(control and other \(e.g., GR)54 144 Q
(TT determination\) purposes.)-.6 E 1.6 -.8(To f)54 168 T(acilitate the\
 baseline NORM-CC scheme described in Section 5.2.2, a NORM-CC Rate hea\
der e).7 E(xtension is de\214ned to)-.15 E
(inform the group of the sender')54 180 Q 2.5(sc)-.55 G
(urrent transmission rate.)-2.5 E
(This is used along with the loss detection "sequence" \214eld of all)5
E(NORM sender messages and the)54 192 Q F1(NORM_CMD\(CC\))2.5 E F0(GR)
2.5 E(TT collection process to support NORM-CC congestion control)-.6 E
2.5(operation. The)54 204 R(format of this header e)2.5 E
(xtension is as follo)-.15 E(ws:)-.25 E F1 114(0123)124.2 228 S 6
(01234567890123456789012345678901)118.2 240 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
252 Q 6(|e)109.2 264 S(xt_type = 128|)-6 E 12(reserved |)24 F 60
(send_rate |)66 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
276 Q/F2 10/Times-Italic@0 SF(NORM-CC Rate Header Extension F)218.345
300 Q(ormat)-1.05 E F0(The "send_rate" \214eld indicates the sender')54
324 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 portion and 4 bits of base 10 e)54 336 Q
(xponent \(order of magnitude\))-.15 E
(information in the least signi\214cant portion.)54 348 Q(The 12-bit ma\
ntissa portion of the \214eld is scaled such that a \215oating point v)5
E(alue)-.25 E(of 0.0 corresponds to 0 and a \215oating point v)54 360 Q
(alue of 10.0 corresponds to 4096.)-.25 E(Thus:)5 E F1(send_rate = \(\(\
\(int\)\(Value_mantissa * 4096.0 / 10.0 + 0.5\)\) << 4\) | Value_expone\
nt;)58.2 384 Q F0 -.15(Fo)54 408 S 2.5(re).15 G(xample, to represent a \
transmission rate of 256kbps \(3.2e+04 bytes per second\), the lo)-2.65
E(wer 4 bits of the 16-bit \214eld)-.25 E(contain a v)54 420 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(equation gi)54 432 Q -.15
(ve)-.25 G 2.5(na).15 G(bo)-2.5 E -.15(ve)-.15 G(:).15 E F1
(send_rate = \(\(\(int\)\(\(3.2 * 4096.0 / 10.0\) + 0.5\)\) << 4\) | 4;)
54 456 Q 6(=\()114 480 S(0x51f << 4\) | 0x4)-6 E 6(=0)114 504 S(x51f4)-6
E F0 1.6 -.8(To d)54 528 T(ecode the "send_rate" \214eld, the follo).8 E
(wing equation can be used:)-.25 E F1(value = \(send_rate >> 4\) * 10.0\
 / 4096.0 * power\(10.0, \(send_rate & x000f\)\))79.2 552 Q F0(Note the\
 maximum transmission rate representable by this scheme is approximatel\
y 9.99e+15 bytes per second.)54 576 Q(When this e)54 600 Q(xtension is \
present, a "cc_node_list" may be attached as the payload of the)-.15 E
F1(NORM_CMD\(CC\))2.5 E F0 2.5(message. The)2.5 F
(presence of this header e)54 612 Q
(xtension also implies that NORM recei)-.15 E -.15(ve)-.25 G
(rs should respond according to the procedures described in).15 E
(Section 5.2.2.)54 624 Q(The "cc_node_list" consists of a list of)54 648
Q F2(NormNodeIds)2.5 E F0
(and their associated congestion control status.)2.5 E
(This includes the)5 E(Adamson, Bormann, 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
(June 2003)185.175 E(current limiting recei)54 84 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 that ha)-2.5 E .3 -.15
(ve b)-.2 H(een identi\214ed, and some).15 E(number of recei)54 96 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)54 108 R
(maximum 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.)54 120 Q
(The list length can be inferred from the length of the)5 E/F1 10
/Courier@0 SF(NORM_CMD\(CC\))2.5 E F0(message.)54 132 Q
(Each item in the "cc_node_list" is in the follo)54 156 Q(wing format:)
-.25 E F1 114(0123)124.2 180 S 6(01234567890123456789012345678901)118.2
192 S(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 204 Q 156(|c)109.2 216 S 156(c_node_id |)-156 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
228 Q 24(|c)109.2 240 S 12(c_flags |)-24 F 18(cc_rtt |)30 F 66
(cc_rate |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
252 Q/F2 10/Times-Italic@0 SF(Cong)218.465 276 Q(estion Contr)-.1 E
(ol Node List Item F)-.45 E(ormat)-1.05 E F0(The "cc_node_id" is the)54
300 Q F2(NormNodeId)2.5 E F0(of the recei)2.5 E -.15(ve)-.25 G 2.5(rw)
.15 G(hich the item represents.)-2.5 E(The "cc_\215ags" \214eld contain\
s \215ags indicating the congestion control status of the indicated rec\
ei)54 324 Q -.15(ve)-.25 G 3.6 -.55(r. T).15 H(he follo).55 E
(wing \215ags are)-.25 E(de\214ned:)54 336 Q .4 LW 533.585 358.5 74.815
358.5 DL 57.61(Flag V)124.925 368 R 140.39(alue Purpose)-1.11 F 533.585
372.5 74.815 372.5 DL F1(NORM_FLAG_CC_CLR)79.815 382 Q F0(0x01)28.385 E
(Recei)240.585 382 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 533.585 386.5 74.815 386.5 DL F1(NORM_FLAG_CC_PLR)79.815 396 Q F0
(0x02)28.385 E(Recei)240.585 396 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 533.585 400.5 74.815 400.5 DL F1(NORM_FLAG_CC_RTT)79.815
410 Q F0(0x04)28.385 E(Recei)240.585 410 Q -.15(ve)-.25 G 2.5(rh).15 G
(as measured R)-2.5 E(TT with respect to sender)-.6 E(.)-.55 E 533.585
414.5 74.815 414.5 DL F1(NORM_FLAG_CC_START)79.815 424 Q F0(0x08)16.385
E(Sender/recei)240.585 424 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(\(i.e. The recei)
240.585 436 Q -.15(ve)-.25 G 2.5(rh).15 G(as not yet detected an)-2.5 E
2.5(yp)-.15 G(ack)-2.5 E(et loss and the "cc_rate")-.1 E
(\214eld is the recei)240.585 448 Q -.15(ve)-.25 G(r').15 E 2.5(sa)-.55
G(ctual measured recei)-2.5 E .3 -.15(ve r)-.25 H(ate\).).15 E 533.585
452.5 74.815 452.5 DL F1(NORM_FLAG_CC_LEAVE)79.815 462 Q F0(0x10)16.385
E(Recei)240.585 462 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.)240.585 474 Q 533.585
478.5 74.815 478.5 DL 533.585 358.5 533.585 478.5 DL 74.815 358.5 74.815
478.5 DL 233.085 358.5 233.085 478.5 DL 195.315 358.5 195.315 478.5 DL
(The "cc_rtt" contains a quantized representation of the recei)54 504 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)
54 516 Q 5(.T)-.55 G(his \214eld is v)-5 E(alid only if the)-.25 E F1
(NORM_FLAG_CC_RTT)2.5 E F0(\215ag is set in the "cc_\215ags" \214eld.)
2.5 E(This one byte \214eld is a)5 E(quantized representation of the R)
54 528 Q(TT using the algorithm described in the NORM Building Block do\
cument [15].)-.6 E
(The "cc_rate" \214eld contains a representation of the recei)54 552 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 \(during the "slo)54 564 Q 2.5(ws)
-.25 G(tart" phase\) congestion control rate.)-2.5 E
(This \214eld is encoded and decoded)5 E
(using the same technique as described for the)54 576 Q F1
(NORM_CMD\(CC\))2.5 E F0("send_rate" \214eld.)2.5 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Times-BoldItalic@0 SF(NORM_CMD\(REP)54 84 Q
(AIR_AD)-.85 E(V\) Message)-.5 E F0(The)54 108 Q/F2 10/Courier@0 SF
(NORM_CMD\(REPAIR_ADV\))2.5 E F0(message is used by the sender to "adv)
2.5 E(ertise" its aggre)-.15 E -.05(ga)-.15 G(ted repair state from).05
E F2(NORM_NACK)2.5 E F0(messages accumulated during a repair c)54 120 Q
(ycle and/or congestion control feedback recei)-.15 E -.15(ve)-.25 G 2.5
(d. This).15 F(message is sent only when)2.5 E(the sender has recei)54
132 Q -.15(ve)-.25 G(d).15 E F2(NORM_NACK)2.5 E F0(and/or)2.5 E F2
(NORM_ACK\(CC\))2.5 E F0
(\(when congestion control is enabled\) messages via unicast)2.5 E
(transmission instead of multicast.)54 144 Q
(By "echoing" this information to the recei)5 E -.15(ve)-.25 G 2.5(rs)
.15 G(et, suppression of feedback can be achie)-2.5 E -.15(ve)-.25 G(d)
.15 E -2.15 -.25(ev e)54 156 T 2.5(nw).25 G(hen recei)-2.5 E -.15(ve)
-.25 G(rs are unicasting that feedback instead of multicasting it among\
 the group[11].).15 E F2 114(0123)124.2 180 S 6
(01234567890123456789012345678901)118.2 192 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q(|version| type=3|)109.2 216 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
228 Q 162(|s)109.2 240 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
252 Q 60(|s)109.2 264 S 60(ession_id |)-60 F 30(grtt |)30 F 24(gsize |)
30 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 276 Q 12(|f)109.2 288 S(lavor = 5)-12 E 30(|f)18 G 24(lags |)-30 F
60(reserved |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
300 Q 90(|h)109.2 312 S(eader extensions \(if applicable\))-90 E(|)90 E
180(|.)109.2 324 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
336 Q 138(|r)109.2 348 S 126(epair_adv_payload |)-138 F 180(|.)109.2 360
S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
372 Q/F3 10/Times-Italic@0 SF(NORM_CMD\(REP)210.215 396 Q(AIR_AD)-.9 E
(V\) Messa)-.4 E .2 -.1(ge F)-.1 H(ormat)-.95 E F0
(The "session_id", "grtt", "gsize", and "\215a)54 420 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 2.5(messages. The)2.5 F -.25(va)2.5 G(lue of).25 E
(the "hdr_len" \214eld when no e)54 432 Q(xtensions are present is 4.)
-.15 E(The "\215ags" \214eld pro)54 456 Q(vide information on the)-.15 E
F2(NORM_CMD\(REPAIR_ADV\))2.5 E F0 2.5(content. There)2.5 F
(is currently one)2.5 E F2(NORM_CMD\(REPAIR_ADV\))54 468 Q F0
(\215ag de\214ned:)2.5 E F2(NORM_REPAIR_ADV_FLAG_LIMIT = 0x01)205.2 492
Q F0(This \215ag is set by the sender when it is unable to \214t its fu\
ll current repair state into a single)54 516 Q F3(NormSe)2.5 E
(gmentSize)-.4 E F0 5(.I)C 2.5(ft)-5 G(his \215ag is)-2.5 E(set, recei)
54 528 Q -.15(ve)-.25 G(rs should limit their N).15 E -.4(AC)-.35 G 2.5
(Kr).4 G(esponse to generating N)-2.5 E -.4(AC)-.35 G 2.5(Kc).4 G
(ontent only up through the maximum ordinal)-2.5 E
(transmission position)54 540 Q F3(\(objectId::fecP)2.5 E(ayloadId\))-.8
E F0(included in the "repair_adv_content".)2.5 E
(When congestion control operation is enabled, a header e)54 564 Q
(xtension may be applied to the)-.15 E F2(NORM_CMD\(REPAIR_ADV\))2.5 E
F0(representing the most limiting \(in terms of congestion control feed\
back suppression\) congestion control response.)54 576 Q(This)5 E(allo)
54 588 Q(ws the)-.25 E F2(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(message to suppress recei)2.5 E -.15(ve)-.25 G 2.5(rc).15 G
(ongestion control responses as well as N)-2.5 E -.4(AC)-.35 G(K).4 E
(feedback messages.)54 600 Q(The \214eld is de\214ned as a header e)5 E
(xtension so that alternati)-.15 E .3 -.15(ve c)-.25 H
(ongestion control schemes may be used).15 E(with NORM without re)54 612
Q(vision to this document.)-.25 E 2.5(AN)5 G(ORM-CC Feedback header e)
-2.5 E(xtension is de\214ned to encapsulate)-.15 E
(congestion control feedback within)54 624 Q F2(NORM_NACK)2.5 E F0(,)A
F2(NORM_ACK)2.5 E F0 2.5(,a)C(nd)-2.5 E F2(NORM_CMD\(REPAIR_ADV\))2.5 E
F0 2.5(messages. If)2.5 F(another)2.5 E(congestion control technique \(\
e.g., Pragmatic General Multicast Congestion Control \(PGMCC\)\) is use\
d within a NORM)54 636 Q(implementation, an additional header e)54 648 Q
(xtension MA)-.15 E 2.5(Yn)-1.05 G(eed to be de\214ned encapsulate an)
-2.5 E 2.5(yr)-.15 G(equired feedback content.)-2.5 E(The)5 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(NORM-CC Feedback Header Extension format is:)54 84
Q/F1 10/Courier@0 SF
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q 12(|e)109.2 120 S(xt_type = 3 |)-12 E(ext_len = 3)12 E 60(|c)12 G
54(c_sequence |)-60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 24(|c)109.2 144 S 12(c_flags |)-24 F 18(cc_rtt |)30 F 66
(cc_loss |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 72(|c)109.2 168 S 66(c_rate |)-72 F 54(cc_reserved |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
180 Q/F2 10/Times-Italic@0 SF(NORM-CC F)208.55 204 Q(eedbac)-.75 E 2.5
(kH)-.2 G(eader Extension F)-2.5 E(ormat)-1.05 E F0(The "cc_sequence" \
\214eld contains the current greatest "cc_sequence" v)54 228 Q
(alue recei)-.25 E -.15(ve)-.25 G(rs ha).15 E 2.8 -.15(ve r)-.2 H(ecei)
.15 E -.15(ve)-.25 G 2.5(di).15 G(n)-2.5 E F1(NORM_CMD\(CC\))2.5 E F0
(messages from the sender)54 240 Q 5(.T)-.55 G(his information assists \
the sender in congestion control operation by pro)-5 E
(viding an indicator of)-.15 E(ho)54 252 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 successfully)-2.5 E(recei)54 264 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 recent)-.25 E(congestion control probes \
\(and thus possibly other messages from the sender\), the sender may ch\
oose to tak)54 276 Q 2.5(ec)-.1 G(ongestion)-2.5 E -.2(avo)54 288 S
(idance measures.).2 E -.15(Fo)5 G(r).15 E F1(NORM_CMD\(REPAIR_ADV\))2.5
E F0(messages, the sender SHALL set the "cc_sequence" \214eld v)2.5 E
(alue to)-.25 E(the v)54 300 Q(alue set in the last)-.25 E F1
(NORM_CMD\(CC\))2.5 E F0(message sent.)2.5 E
(The "cc_\215ags" \214eld contains bits representing the recei)54 324 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)54 336 S
(lues for the "cc_\215ags" \214eld are those speci\214ed for the).25 E
F1(NORM_CMD\(CC\))2.5 E F0(message node list item \215ags.)2.5 E
(These \214elds are)5 E(used by recei)54 348 Q -.15(ve)-.25 G(rs in con\
trolling \(suppressing as necessary\) their congestion control feedback\
.).15 E -.15(Fo)5 G(r).15 E F1(NORM_CMD\(REPAIR_ADV\))54 360 Q F0
(messages, the NORM_FLA)2.5 E(G_CC_R)-.4 E(TT should be set)-.6 E F2
(only)2.5 E F0(when)2.5 E F2(all)2.5 E F0(feedback messages)2.5 E(recei)
54 372 Q -.15(ve)-.25 G 2.5(db).15 G 2.5(yt)-2.5 G(he sender ha)-2.5 E
.3 -.15(ve t)-.2 H(he \215ag set.).15 E(Similarly)5 E 2.5(,t)-.65 G
(he NORM_FLA)-2.5 E(G_CC_CLR or NORM_FLA)-.4 E(G_CC_PLR should be set)
-.4 E(only when)54 384 Q F2(no)2.5 E F0(feedback has been recei)2.5 E
-.15(ve)-.25 G 2.5(df).15 G(rom non-CLR or non-PLR recei)-2.5 E -.15(ve)
-.25 G 2.5(rs. And).15 F(the NORM_FLA)2.5 E(G_CC_LEA)-.4 E(VE)-1.35 E
(should be set only when all feedback messages the sender has recei)54
396 Q -.15(ve)-.25 G 2.5(dh).15 G -2.25 -.2(av e)-2.5 H
(this \215ag set.)2.7 E(These heuristics for setting the)5 E(\215ags in)
54 408 Q F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0(ensure the most ef)2.5 E
(fecti)-.25 E .3 -.15(ve s)-.25 H(uppression of recei).15 E -.15(ve)-.25
G(rs pro).15 E(viding unicast feedback)-.15 E(messages.)54 420 Q
(The "cc_rtt" \214eld SHALL be set to a def)54 444 Q(ault maximum v)-.1
E(alue and the)-.25 E F1(NORM_FLAG_CC_RTT)2.5 E F0
(\215ag SHALL be cleared when)2.5 E(no recei)54 456 Q -.15(ve)-.25 G 2.5
(rh).15 G(as yet recei)-2.5 E -.15(ve)-.25 G 2.5(dR).15 G
(TT measurement information.)-3.1 E(When a 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 information, it)-3.1 E(shall set the "cc_rtt" v)54 468 Q
(alue accordingly and set the)-.25 E F1(NORM_FLAG_CC_RTT)2.5 E F0
(\215ag in the "cc_\215ags" \214eld.)2.5 E -.15(Fo)5 G(r).15 E F1
(NORM_CMD\(REPAIR_ADV\))54 480 Q F0
(messages, the sender SHALL set the "cc_rtt" \214eld v)2.5 E
(alue to the lar)-.25 E(gest non-CLR/non-PLR)-.18 E -.6(RT)54 492 S 2.5
(Ti).6 G 2.5(th)-2.5 G(as measured from recei)-2.5 E -.15(ve)-.25 G
(rs for the current feedback round.).15 E
(The "cc_loss" \214eld reperesents the recei)54 516 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)5 E(is a v)54 528 Q(alue from 0.0 to 1.0 correspondi\
ng to a range of zero to 100 percent pack)-.25 E
(et loss. The 16-bit "cc_loss" v)-.1 E(alue is)-.25 E
(calculated by the follo)54 540 Q(wing formula:)-.25 E F1
("cc_loss" = decimal_loss_fraction * 65535.0)175.2 564 Q F0 -.15(Fo)54
588 S(r).15 E F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(messages, the sender SHALL set the "cc_loss" \214eld v)2.5 E
(alue to the lar)-.25 E(gest non-CLR/non-)-.18 E
(PLR loss estimate it has recei)54 600 Q -.15(ve)-.25 G 2.5(df).15 G
(rom recei)-2.5 E -.15(ve)-.25 G(rs for the current feedback round.).15
E(The "cc_rate" \214eld represents the recei)54 624 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)54 636 Q(alue is set to twice the actual rat\
e it has measured from the corresponding sender and the)-.25 E(NORM_FLA)
54 648 Q(G_CC_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
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(on its loss measurement and R)54 84 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 -.15(Fo)5 G
(r).15 E/F1 10/Courier@0 SF(NORM_CMD\(REPAIR_ADV\))54 96 Q F0
(messages, the sender SHALL set the "cc_loss" \214eld v)2.5 E
(alue to the lo)-.25 E(west non-CLR/non-PLR)-.25 E
("cc_rate" report it has recei)54 108 Q -.15(ve)-.25 G 2.5(df).15 G
(rom recei)-2.5 E -.15(ve)-.25 G(rs for the current feedback round.).15
E(The "cc_reserv)54 132 Q(ed" \214eld is reserv)-.15 E
(ed for future NORM protocol use.)-.15 E(Currently)5 E 2.5(,s)-.65 G
(enders SHALL set this \214eld to ZER)-2.5 E(O, and)-.4 E(recei)54 144 Q
-.15(ve)-.25 G(rs SHALL ignore the content of this \214eld.).15 E
(The "repair_adv_payload" is in e)54 168 Q
(xactly the same form as the "nack_content" of)-.15 E F1(NORM_NACK)2.5 E
F0(messages and can be processed)2.5 E(by recei)54 180 Q -.15(ve)-.25 G
(rs for suppression purposes in the same manner).15 E 2.5(,w)-.4 G
(ith the e)-2.5 E(xception of the condition when the)-.15 E(NORM_REP)54
192 Q(AIR_AD)-.92 E(V_FLA)-.4 E(G_LIMIT is set.)-.4 E/F2 10
/Times-BoldItalic@0 SF(NORM_CMD\(A)54 216 Q(CK_REQ\) Message)-.65 E F0
(The)54 240 Q F1(NORM_CMD\(ACK_REQ\))2.5 E F0
(message is used by the sender to request ackno)2.5 E
(wledgement from a speci\214ed list of recei)-.25 E -.15(ve)-.25 G(rs.)
.15 E(This message is used in pro)54 252 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.)54 264 Q 2.5(Ar)5 G(ange of ackno)-2.5
E(wledgement request types is pro)-.25 E
(vided for use at the application')-.15 E 2.5(sd)-.55 G(iscretion.)-2.5
E(Pro)54 276 Q(vision for application-de\214ned, positi)-.15 E -.15(ve)
-.25 G(ly-ackno).15 E(wledged commands allo)-.25 E
(ws the application to automatically tak)-.25 E(e)-.1 E(adv)54 288 Q
(antage of transmission and round-trip timing information a)-.25 E -.25
(va)-.2 G(ilable to the NORM protocol.).25 E(The details of the NORM)5 E
(positi)54 300 Q .3 -.15(ve a)-.25 H(ckno).15 E
(wledgement process including transmission of the)-.25 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(messages and the recei)2.5 E -.15(ve)-.25
G(r).15 E(response \()54 312 Q F1(NORM_ACK)A F0 2.5(\)a)C
(re described in Section 5.5.3.)-2.5 E(The format of the)5 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(message is:)2.5 E F1 114(0123)124.2 336 S
6(01234567890123456789012345678901)118.2 348 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
360 Q(|version| type=3|)109.2 372 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
384 Q 162(|s)109.2 396 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
408 Q 60(|s)109.2 420 S 60(ession_id |)-60 F 30(grtt |)30 F 24(gsize |)
30 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 432 Q 12(|f)109.2 444 S(lavor = 6)-12 E 24(|r)18 G 12(eserved |)
-24 F 12(ack_type |)24 F 24(ack_id |)24 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
456 Q 138(|a)109.2 468 S 138(cking_node_list |)-138 F 180(|.)109.2 480 S
174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
492 Q/F3 10/Times-Italic@0 SF(NORM_CMD\(A)216.93 516 Q(CK_REQ\) Messa)
-.3 E .2 -.1(ge F)-.1 H(ormat)-.95 E F0
(The NORM common message header and standard)54 540 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 v)5
E(alue of the "hdr_len")-.25 E(\214eld for)54 552 Q F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(messages with no header e)2.5 E
(xtension present is 4.)-.15 E(Adamson, Bormann, 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
(June 2003)185.175 E(The "ack_type" \214eld indicates the type of ackno)
54 84 Q(wledgement 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 96 Q(The follo)5 E(wing "ack_type" v)-.25 E
(alues are de\214ned and are also used in)-.25 E/F1 10/Courier@0 SF
(NORM_ACK)2.5 E F0(messages described later:)2.5 E .4 LW 515.365 118.5
93.035 118.5 DL -.4(AC)136.555 128 S 2.5(KT).4 G 53.8(ype V)-3.3 F
112.42(alue Purpose)-1.11 F 515.365 132.5 93.035 132.5 DL F1
(NORM_ACK_CC)98.035 142 Q F0(1)92.33 E(Used to identify)276.365 142 Q F1
(NORM_ACK)2.5 E F0(messages sent in response to)2.5 E F1(NORM_CMD\(CC\))
276.365 154 Q F0(messages.)2.5 E 515.365 158.5 93.035 158.5 DL F1
(NORM_ACK_FLUSH)98.035 168 Q F0(2)74.33 E(Used to identify)276.365 168 Q
F1(NORM_ACK)2.5 E F0(messages sent in response to)2.5 E F1
(NORM_CMD\(FLUSH\))276.365 180 Q F0(messages.)2.5 E 515.365 184.5 93.035
184.5 DL F1(NORM_ACK_RESERVED)98.035 194 Q F0(3-15)43 E(Reserv)276.365
194 Q(ed for possible future NORM protocol use.)-.15 E 515.365 198.5
93.035 198.5 DL F1(NORM_ACK_APPLICATION)98.035 208 Q F0(16-255)15 E
(Used at application')276.365 208 Q 2.5(sd)-.55 G(iscretion.)-2.5 E
515.365 212.5 93.035 212.5 DL 515.365 118.5 515.365 212.5 DL 93.035
118.5 93.035 212.5 DL 268.865 118.5 268.865 212.5 DL 225.535 118.5
225.535 212.5 DL(The)54 238 Q F1(NORM_ACK_CC)2.5 E F0 -.25(va)2.5 G
(lue is pro).25 E(vided for use only in)-.15 E F1(NORM_ACKs)2.5 E F0
(generated in response to the)2.5 E F1(NORM_CMD\(CC\))2.5 E F0
(messages used in congestion control operation.)54 250 Q(Similarly)5 E
2.5(,t)-.65 G(he)-2.5 E F1(NORM_ACK_FLUSH)2.5 E F0(is pro)2.5 E
(vided for use only in)-.15 E F1(NORM_ACKs)2.5 E F0
(generated in response to applicable)54 262 Q F1(NORM_CMD\(FLUSH\))2.5 E
F0(messages.)2.5 E F1(NORM_CMD)5 E F0(\(A)A
(CK_REQ\) messages with "ack_type" of)-.4 E F1(NORM_ACK_CC)54 274 Q F0
(or)2.5 E F1(NORM_ACK_FLUSH)2.5 E F0(SHALL NO)2.5 E 2.5(Tb)-.4 G 2.5(eg)
-2.5 G(enerated by the sender)-2.5 E(.)-.55 E(The)54 298 Q F1
(NORM_ACK_RESERVED)2.5 E F0(range of "ack_type" v)2.5 E(alues is pro)
-.25 E(vided for possible future NORM protocol use.)-.15 E(The)54 322 Q
F1(NORM_ACK_APPLICATION)2.5 E F0(range of "ack_type" v)2.5 E
(alues is pro)-.25 E(vided so that NORM applications may implement)-.15
E(application-de\214ned, positi)54 334 Q -.15(ve)-.25 G(ly-ackno).15 E
(wledged commands that are able to le)-.25 E -.15(ve)-.25 G
(rage internal transmission and round-trip timing).15 E(information a)54
346 Q -.25(va)-.2 G(ilable to the NORM protocol implementation.).25 E
(The "ack_id" pro)54 370 Q(vides a sequenced identi\214er for the gi)
-.15 E -.15(ve)-.25 G(n).15 E F1(NORM_CMD\(ACK_REQ\))2.5 E F0 2.5
(message. This)2.5 F("ack_id" is returned in)2.5 E F1(NORM_ACK)54 382 Q
F0(messages generated by the recei)2.5 E -.15(ve)-.25 G(rs so that the \
sender may associate the response with its corresponding).15 E(request.)
54 394 Q(The "reserv)54 418 Q(ed" \214eld is reserv)-.15 E
(ed for possible future protocol use and SHALL be set to ZER)-.15 E 2.5
(Ob)-.4 G 2.5(ys)-2.5 G(enders and ignored by)-2.5 E(recei)54 430 Q -.15
(ve)-.25 G(rs.).15 E(The "acking_node_list" \214eld contains the)54 454
Q/F2 10/Times-Italic@0 SF(NormNodeIds)2.5 E F0
(of the current NORM recei)2.5 E -.15(ve)-.25 G
(rs that are desired to pro).15 E(vide positi)-.15 E -.15(ve)-.25 G
(ackno)54 466 Q(wledge \()-.25 E F1(NORM_ACK)A F0 2.5(\)t)C 2.5(ot)-2.5
G(his request.)-2.5 E(The pack)5 E
(et payload length implies the length of the "acking_node_list" and its)
-.1 E(length is limited to the sender)54 478 Q F2(NormSe)2.5 E
(gmentSize)-.4 E F0 5(.T)C(he indi)-5 E(vidual)-.25 E F2(NormNodeId)2.5
E F0(items are listed in netw)2.5 E(ork \(Big Endian\) byte)-.1 E(order)
54 490 Q 5(.I)-.55 G 2.5(far)-5 G(ecei)-2.5 E -.15(ve)-.25 G(r').15 E(s)
-.55 E F2(NormNodeId)2.5 E F0(is included in the "acking_node_list", it\
 SHALL schedule transmission of a)2.5 E F1(NORM_ACK)2.5 E F0
(message as described in Section 5.5.3.)54 502 Q/F3 10
/Times-BoldItalic@0 SF(NORM_CMD\(APPLICA)54 526 Q(TION\) Message)-.55 E
F0(This command allo)54 550 Q(ws the NORM application to rob)-.25 E
(ustly transmit application-de\214ned commands.)-.2 E
(The command message)5 E(preempts an)54 562 Q 2.5(yo)-.15 G
(ngoing data transmission and is repeated up to)-2.5 E F1
(NORM_ROBUST_FACTOR)2.5 E F0(times at a rate of once per)2.5 E F1
(2*GRTT)54 574 Q F0 5(.T)C(his rate of repetition allo)-5 E
(ws the application to observ)-.25 E 2.5(ea)-.15 G .3 -.15(ny r)-2.5 H
(esponse \(if that is the application').15 E 2.5(sp)-.55 G
(urpose for the)-2.5 E(command\) before it is repeated.)54 586 Q
(Possible responses may include initiation of data transmission , other)
5 E F1(NORM_CMD\(APPLICATION\))54 598 Q F0(messages, or e)2.5 E -.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)-.25 E F2(NormSession)54 610
Q F0 2.5(participants. The)2.5 F
(transmission of these commands will preempt data transmission when the)
2.5 E 2.5(ya)-.15 G(re scheduled)-2.5 E(and may be multiple)54 622 Q
-.15(xe)-.15 G 2.5(dw).15 G(ith ongoing data transmission.)-2.5 E
(This type of rob)5 E(ustly transmitted command allo)-.2 E(ws NORM)-.25
E(applications to de\214ne a complete set of session control mechanisms\
 with less state than the transfer of FEC encoded reliable)54 634 Q
(content requires while taking adv)54 646 Q
(antage of NORM transmission and round-trip timing information.)-.25 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 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
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q(|version| type=3|)109.2 120 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 162(|s)109.2 144 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 60(|s)109.2 168 S 60(ession_id |)-60 F 30(grtt |)30 F 24(gsize |)
30 F(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
109.2 180 Q 12(|f)109.2 192 S(lavor = 7)-12 E 120(|r)18 G 108(eserved |)
-120 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 114(|A)109.2 216 S(pplication-Defined Content)-114 E(|)102 E 180
(|.)109.2 228 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
240 Q/F2 10/Times-Italic@0 SF(NORM_CMD\(APPLICA)207.52 264 Q
(TION\) Messa)-.37 E .2 -.1(ge F)-.1 H(ormat)-.95 E F0
(The NORM common message header and)54 288 Q F1(NORM_CMD)2.5 E F0
(\214elds are interpreted as pre)2.5 E(viously described.)-.25 E(The v)5
E(alue of the)-.25 E F1(NORM_CMD\(APPLICATION\))54 300 Q F0
("hdr_len" \214eld when no header e)2.5 E(xtensions are present is 4.)
-.15 E(The "Application-De\214ned Content" area contains information in\
 a format at the discretion of the application.)54 324 Q(The size of)5 E
(this payload SHALL be limited to a maximum of the sender')54 336 Q(s)
-.55 E F2(NormSe)2.5 E(gmentSize)-.4 E F0(setting.)2.5 E/F3 10
/Times-Bold@0 SF(4.3 Recei)36 360 Q -.1(ve)-.1 G 2.5(rM).1 G(essages)
-2.5 E F0(The NORM message types generated by pariticipating recei)54
384 Q -.15(ve)-.25 G(rs consist of).15 E F1(NORM_NACK)2.5 E F0(and)2.5 E
F1(NORM_ACK)2.5 E F0(message types.)2.5 E F1(NORM_NACK)54 396 Q F0(mess\
ages are sent to request repair of missing data content from sender tra\
nsmission and)2.5 E F1(NORM_ACK)2.5 E F0(messages are generated in resp\
onse to certain sender commands including)54 408 Q F1(NORM_CMD\(CC\))2.5
E F0(and)2.5 E F1(NORM_CMD\(ACK_REQ\))2.5 E F0(.)A/F4 10
/Times-BoldItalic@0 SF(4.3.1 NORM_N)54 432 Q -.65(AC)-.3 G 2.5(KM).65 G
(essage)-2.5 E F0(The principal purpose of)54 456 Q F1(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)54 468
Q(wledgement upon detection of incomplete data.)-.25 E F1(NORM_NACK)5 E
F0(messages will be transmitted according to the rules of)2.5 E F1
(NORM_NACK)54 480 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
492 Q(vide assistance in promoting protocol scalability and)-.15 E(ef)54
504 Q(\214cienc)-.25 E 2.5(yw)-.15 G(hen a)-2.5 E -.25(va)-.2 G(ilable.)
.25 E F1(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.)54 516
Q(The payload of)54 540 Q F1(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)54 552 R F1
(NORM_NACK)2.5 E F0(message format is as follo)2.5 E(ws:)-.25 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 E(age 29])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q(|version| type=4|)109.2 120 Q 18(hdr_len |)24 F 60(sequence |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 162(|s)109.2 144 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 162(|s)109.2 168 S 156(erver_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
180 Q 66(|s)109.2 192 S 54(ession_id |)-66 F 60(reserved |)72 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 138(|g)109.2 216 S 132(rtt_response_sec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
228 Q 138(|g)109.2 240 S 126(rtt_response_usec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
252 Q 90(|h)109.2 264 S(eader extensions \(if applicable\))-90 E(|)90 E
180(|.)109.2 276 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
288 Q 156(|n)109.2 300 S 144(ack_payload |)-156 F 180(|.)109.2 312 S 174
(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
324 Q/F2 10/Times-Italic@0 SF(NORM_N)240.39 348 Q -.3(AC)-.27 G 2.5(KM)
.3 G(essa)-2.5 E .2 -.1(ge F)-.1 H(ormat)-.95 E F0
(The NORM common message header \214elds serv)54 372 Q 2.5(et)-.15 G
(heir usual purposes.)-2.5 E(The v)5 E
(alue of the "hdr_len" \214eld for)-.25 E F1(NORM_NACK)2.5 E F0
(messages without header e)54 384 Q(xtensions present is 6.)-.15 E
(The "serv)54 408 Q
(er_id" \214eld identi\214es the NORM sender to which the)-.15 E F1
(NORM_NACK)2.5 E F0(message is destined.)2.5 E
(The "session_id" \214eld contains the current session identi\214er gi)
54 432 Q -.15(ve)-.25 G 2.5(nb).15 G 2.5(yt)-2.5 G
(he sender identi\214ed by the "serv)-2.5 E(er_id" \214eld in its)-.15 E
(sender messages.)54 444 Q
(The sender SHOULD ignore feedback messages which contain an in)5 E -.25
(va)-.4 G(lid "session_id" v).25 E(alue.)-.25 E
(The "grtt_response" \214elds contain an adjusted v)54 468 Q
(ersion of the timestamp from the most recently recei)-.15 E -.15(ve)
-.25 G(d).15 E F1(NORM_CMD\(CC\))2.5 E F0
(message for the indicated NORM sender)54 480 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 F1(NORM_CMD\(CC\))54 492 Q F0 5(.T)C 2.5
(he "grtt_response")-5 F -.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\(CC\))54 504 Q F0 2.5
(command. The)2.5 F(recei)2.5 E -.15(ve)-.25 G 2.5(ra).15 G
(djusts the source')-2.5 E(s)-.55 E F1(NORM_CMD\(CC\))2.5 E F0
("send_time" timestamp by adding the time)2.5 E(dif)54 516 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\(CC\))2.5
E F0(to when the)2.5 E F1(NORM_NACK)2.5 E F0
(is transmitted to calculate the)2.5 E -.25(va)54 528 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)73.2 552
Q F0(The recei)54 576 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 it has not yet recei)-2.75 E -.15(ve)-.25 G 2.5
(da).15 G F1(NORM_CMD\(CC\))A F0(message from the indicated sender and \
that the sender should ignore the "grtt_response" in this message.)54
588 Q -.15(Fo)54 612 S 2.5(rN).15 G(ORM-CC operation, the NORM-CC Feedb\
ack Header Extension, as described in the)-2.5 E F1
(NORM_CMD\(REPAIR_ADV})2.5 E F0(message description, is added to)54 624
Q F1(NORM_NACK)2.5 E F0(messages to pro)2.5 E
(vide feedback on the recei)-.15 E -.15(ve)-.25 G
(rs current state with respect to).15 E(congestion control operation.)54
636 Q(Note that alternati)5 E .3 -.15(ve h)-.25 H(eader e).15 E
(xtensions for congestion control feedback may be de\214ned for)-.15 E
(alternati)54 648 Q .3 -.15(ve c)-.25 H
(ongestion control schemes for NORM use in the future.).15 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(The "reserv)54 84 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)54 108 Q/F1 10
/Courier@0 SF(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)54 120 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)54 132 Q(\
gments it requires from the sender in order to complete reliable recept\
ion up to the sender')-.15 E 2.5(st)-.55 G(ransmission position at the)
-2.5 E(moment the recei)54 144 Q -.15(ve)-.25 G 2.5(ri).15 G
(nitiates the N)-2.5 E -.4(AC)-.35 G 2.5(KP).4 G
(rocedure as described in Section 5.3.)-2.5 E 2.5(As)5 G
(ingle NORM Repair Request consists of)-2.5 E 2.5(al)54 156 S(ist of it\
ems, ranges, and/or FEC coding block erasure counts for needed)-2.5 E F1
(NORM_DATA)2.5 E F0(and/or)2.5 E F1(NORM_INFO)2.5 E F0(content.)2.5 E(M\
ultiple repair requests may be concatenated within the "nack_payload" \
\214eld of a)54 168 Q F1(NORM_NACK)2.5 E F0 2.5(message. Note)2.5 F
(that a single)2.5 E(NORM Repair Request can possibly include multiple \
"items", "ranges", or "erasure_counts".)54 180 Q
(In turn, the "nack_payload")5 E
(\214eld may contain multiple repair requests.)54 192 Q 2.5(As)5 G
(ingle NORM Repair Request has the follo)-2.5 E(wing format:)-.25 E F1
114(0123)124.2 216 S 6(01234567890123456789012345678901)118.2 228 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
240 Q 36(|f)109.2 252 S 24(orm | flags |)-36 F 66(length |)78 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
264 Q 132(|r)109.2 276 S 120(epair_request_items |)-132 F 174(|.)109.2
288 S 180(.. |)-174 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
300 Q/F2 10/Times-Italic@0 SF(NORM Repair Request F)242.37 324 Q(ormat)
-1.05 E F0
(The "form" \214eld indicates the type of repair request items gi)54 348
Q -.15(ve)-.25 G 2.5(ni).15 G 2.5(nt)-2.5 G
(he "repair_request_items" list.)-2.5 E(Possible v)5 E(alues for the)
-.25 E("form" \214eld include:)54 360 Q -.15(Fo)274.555 390 S 55.74
(rm V).15 F(alue)-1.11 E F1(NORM_NACK_ITEMS)231.315 402 Q F0(1)41.885 E
F1(NORM_NACK_RANGES)231.315 414 Q F0(2)35.885 E F1(NORM_NACK_ERASURES)
231.315 426 Q F0(3)23.885 E 2.5(A")54 456 S(form" v)-2.5 E(alue of)-.25
E F1(NORM_NACK_ITEMS)2.5 E F0(indicates each repair request item in the\
 "repair_request_items" list is to be treated)2.5 E(as an indi)54 468 Q
(vidual request.)-.25 E 2.5(Av)5 G(alue of)-2.75 E F1(NORM_NACK_RANGES)
2.5 E F0(indicates that the "repair_request_items" list consists of)2.5
E F2(pair)2.5 E(s)-.1 E F0
(of repair request items that correspond to inclusi)54 480 Q .3 -.15
(ve r)-.25 H(anges of repair needs.).15 E(And the)5 E F1
(NORM_NACK_ERASURES)2.5 E F0("form")2.5 E
(indicates that the repair request items are to be treated indi)54 492 Q
(vidually and that the "encoding_symbol_id" portion of the)-.25 E
("fec_payload_id" \214eld of the repair request item \(see belo)54 504 Q
(w\) is to be interpreted as an "erasure count" for the FEC coding)-.25
E(block identi\214ed by the repair request item')54 516 Q 2.5(s")-.55 G
(source_block_number".)-2.5 E(Adamson, Bormann, et al.)36 696 Q
(Expires December 2003)105.89 E([P)119.09 E(age 31])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E
(The "\215ags" \214eld is currently used to indicate the le)54 84 Q -.15
(ve)-.25 G 2.5(lo).15 G 2.5(fd)-2.5 G
(ata content for which the repair request items apply \(i.e. a)-2.5 E
(indi)54 96 Q(vidual se)-.25 E
(gment, entire FEC coding block, or entire transport object\).)-.15 E
(Possible \215ag v)5 E(alues include:)-.25 E .4 LW 530.585 118.5 77.815
118.5 DL 54.61(Flag V)124.925 128 R 140.39(alue Purpose)-1.11 F 530.585
132.5 77.815 132.5 DL/F1 10/Courier@0 SF(NORM_NACK_SEGMENT)82.815 142 Q
F0(0x01)16.385 E(Indicates the listed se)237.585 142 Q
(gment\(s\) or range of se)-.15 E(gments are required as)-.15 E(repair)
237.585 154 Q(.)-.55 E 530.585 158.5 77.815 158.5 DL F1(NORM_NACK_BLOCK)
82.815 168 Q F0(0x02)28.385 E(Indicates the listed block\(s\) or range \
of blocks in entirety are required)237.585 168 Q(as repair)237.585 180 Q
(.)-.55 E 530.585 184.5 77.815 184.5 DL F1(NORM_NACK_INFO)82.815 194 Q
F0(0x04)34.385 E(Indicates that)237.585 194 Q F1(NORM_INFO)2.5 E F0
(is required as repair for the listed object\(s\).)2.5 E 530.585 198.5
77.815 198.5 DL F1(NORM_NACK_OBJECT)82.815 208 Q F0(0x08)22.385 E(Indic\
ates the listed object\(s\) or range of objects in entirety are require\
d)237.585 208 Q(as repair)237.585 220 Q(.)-.55 E 530.585 224.5 77.815
224.5 DL 530.585 118.5 530.585 224.5 DL 77.815 118.5 77.815 224.5 DL
230.085 118.5 230.085 224.5 DL 192.315 118.5 192.315 224.5 DL(When the)
54 250 Q F1(NORM_NACK_SEGMENT)2.5 E F0(\215ag is set, the "object_trans\
port_id" and "fec_payload_id" \214elds are used to determine)2.5 E
(which sets or ranges of indi)54 262 Q(vidual)-.25 E F1(NORM_DATA)2.5 E
F0(se)2.5 E(gments are needed to repair content at the recei)-.15 E -.15
(ve)-.25 G 3.6 -.55(r. W).15 H(hen the).55 E F1(NORM_NACK_BLOCK)54 274 Q
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 indicated coding block\(s\) and requires)-2.5 E
(transmissions suf)54 286 Q
(\214cient to repair the indicated block\(s\) in their entirety)-.25 E 5
(.W)-.65 G(hen the)-5 E F1(NORM_NACK_INFO)2.5 E F0(\215ag is set, this)
2.5 E(indicates the recei)54 298 Q -.15(ve)-.25 G 2.5(ri).15 G 2.5(sm)
-2.5 G(issing the)-2.5 E F1(NORM_INFO)2.5 E F0(se)2.5 E
(gment for the indicated "object_transport_id".)-.15 E(Note the)5 E F1
(NORM_NACK_INFO)54 310 Q F0(may be set in combination with the)2.5 E F1
(NORM_NACK_BLOCK)2.5 E F0(or)2.5 E F1(NORM_NACK_SEGMENT)2.5 E F0
(\215ags, or may)2.5 E(be set alone.)54 322 Q(When the)5 E F1
(NORM_NACK_OBJECT)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(sm)-2.5 G(issing the entire)-2.5 E/F2 10
/Times-Italic@0 SF(NormT)54 334 Q -.15(ra)-.55 G(nsportObject).15 E F0
(referenced by the "object_transport_id".)2.5 E
(This also implicitly requests an)5 E 2.5(ya)-.15 G -.25(va)-2.7 G
(ilable).25 E F1(NORM_INFO)2.5 E F0(for)2.5 E
(the NormObject, if applicable.)54 346 Q
(The "fec_payload_id" \214eld is ignored when the \215ag)5 E F1
(NORM_NACK_OBJECT)2.5 E F0(is set.)2.5 E(The "length" \214eld v)54 370 Q
(alue is the length in bytes of the "repair_request_items" \214eld.)-.25
E(The "repair_request_items" \214eld consists of a list of indi)54 394 Q
(vidual or range pairs of transport data unit identi\214ers in the)-.25
E(follo)54 406 Q(wing format.)-.25 E F1 114(0123)124.2 430 S 6
(01234567890123456789012345678901)118.2 442 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
454 Q 30(|f)109.2 466 S 18(ec_id |)-30 F 18(reserved |)18 F 30
(object_transport_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
478 Q 144(|f)109.2 490 S 144(ec_payload_id |)-144 F 180(|.)109.2 502 S
174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
514 Q F2(NORM Repair Request Item F)232.235 538 Q(ormat)-1.05 E F0(The \
"fec_id" indicates the FEC type and can be used to determine the format\
 of the "fec_payload_id" \214eld.)54 562 Q(The "reserv)5 E(ed")-.15 E
(\214eld is k)54 574 Q
(ept for possible future use and SHALL be set to a ZER)-.1 E 2.5(Ov)-.4
G(alue and ignored by NORM nodes processing N)-2.75 E -.4(AC)-.35 G(K).4
E(content.)54 586 Q(The "object_transport_id" corresponds to the)54 610
Q F2(NormObject)2.5 E F0
(for which repair is being requested and the "fec_payload_id")2.5 E
(identi\214es the speci\214c FEC coding block and/or se)54 622 Q
(gment being requested.)-.15 E(When the)5 E F1(NORM_NACK_OBJECT)2.5 E F0
(\215ag is set, the)2.5 E -.25(va)54 634 S
(lue of the "fec_payload_id" \214eld is ignored.).25 E(When the)5 E F1
(NORM_NACK_BLOCK)2.5 E F0(\215ag is set, only the FEC code block)2.5 E
(identi\214er portion of the "fec_payload_id" is to be interpreted.)54
646 Q(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 E(age 32])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(The format of the "fec_payload_id" \214eld depends\
 upon the "fec_id" \214eld v)54 84 Q(alue.)-.25 E(When the recei)54 108
Q -.15(ve)-.25 G(r').15 E 2.5(sr)-.55 G(epair needs dictate that dif)
-2.5 E(ferent forms \(mix)-.25 E(ed ranges and/or indi)-.15 E
(vidual items\) or types \(mix)-.25 E(ed speci\214c)-.15 E(se)54 120 Q(\
gments and/or blocks or objects in entirety\) are required to complete \
reliable transmission, multiple NORM Repair)-.15 E(Requests with dif)54
132 Q(ferent "form" and or "\215ags" v)-.25 E
(alues can be concatenated within a single)-.25 E/F1 10/Courier@0 SF
(NORM_NACK)2.5 E F0(message.)2.5 E(Additionally)54 144 Q 2.5(,N)-.65 G
(ORM recei)-2.5 E -.15(ve)-.25 G(rs SHALL construct).15 E F1(NORM_NACK)
2.5 E F0(messages with their repair requests in ordinal order with)2.5 E
(respect to "object_transport_id" and "fec_payload_id" v)54 156 Q 2.5
(alues. The)-.25 F("nack_payload" size SHALL NO)2.5 E 2.5(Te)-.4 G
(xceed the)-2.65 E/F2 10/Times-Italic@0 SF(NormSe)54 168 Q(gmentSize)-.4
E F0(for the sender to which the)2.5 E F1(NORM_NACK)2.5 E F0
(is destined.)2.5 E/F3 10/Times-BoldItalic@0 SF(NORM_N)54 192 Q -.65(AC)
-.3 G 2.5(KC).65 G(ontent Examples:)-2.5 E F0(In these e)54 216 Q(xampl\
es, a small block, systematic FEC code \("fec_id" = 129\) is assumed wi\
th a user data block length of 32)-.15 E(se)54 228 Q 2.5(gments. In)-.15
F(Example 1, a list of indi)2.5 E(vidual)-.25 E F1(NORM_NACK_ITEMS)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_RANGES)54 240 Q F0
(requests _and_ a single)2.5 E F1(NORM_NACK_ITEMS)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 could also be pro)2.5 E
(vided in each case.)-.15 E(Ho)54 264 Q(we)-.25 E -.15(ve)-.25 G .8 -.4
(r, t).15 H(he erasure counts are not really necessary since the sender\
 can easily determine the erasure count while).4 E(processing the N)54
276 Q -.4(AC)-.35 G 2.5(Kc).4 G 2.5(ontent. Ho)-2.5 F(we)-.25 E -.15(ve)
-.25 G .8 -.4(r, t).15 H(he erasure count option may be useful for oper\
ation with other FEC codes or for).4 E
(Generic Router Assist \(GRA\) purposes.)54 288 Q(Example 1:)54 312 Q F1
(NORM_NACK)5 E F0("nack_payload" 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 = 1)-18 E 6(|f)24 G(lags = 0x01)-6 E 42(|l)12 G
6(ength =)-42 F 66(36 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
384 Q 12(|f)54 396 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(2|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
408 Q 120(|s)54 420 S(ource_block_number = 3)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
432 Q 24(|s)54 444 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 2)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
456 Q 12(|f)54 468 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(2|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
480 Q 120(|s)54 492 S(ource_block_number = 3)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
504 Q 24(|s)54 516 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 5)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
528 Q 12(|f)54 540 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(2|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
552 Q 120(|s)54 564 S(ource_block_number = 3)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
576 Q 24(|s)54 588 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 8)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
600 Q F0(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89
E([P)119.09 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
(June 2003)185.175 E(Example 2:)54 84 Q/F1 10/Courier@0 SF(NORM_NACK)5 E
F0("nack_payload" 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)54 96 Q 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 = 2)-18 E 6(|f)24 G(lags = 0x01)-6 E 42(|l)12 G
6(ength =)-42 F 66(24 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
168 Q 12(|f)54 180 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(8|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
192 Q 120(|s)54 204 S(ource_block_number = 6)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
216 Q 24(|s)54 228 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 5)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
240 Q 12(|f)54 252 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(8|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
264 Q 120(|s)54 276 S(ource_block_number = 6)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
288 Q 24(|s)54 300 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 10)-24 E(|)24 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
312 Q 18(|f)54 324 S(orm = 1)-18 E 6(|f)24 G(lags = 0x05)-6 E 42(|l)12 G
6(ength =)-42 F 66(12 |)6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
336 Q 12(|f)54 348 S(ec_id = 129 |)-12 E 18
(reserved | object_transport_id)18 F 6(=1)6 G 18(9|)-6 G
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
360 Q 120(|s)54 372 S(ource_block_number = 1)-120 E(|)120 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
384 Q 24(|s)54 396 S(ource_block_length = 32)-24 E 24(|e)18 G
(ncoding_symbol_id = 3)-24 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)54
408 Q/F2 10/Times-BoldItalic@0 SF(4.3.2 NORM_A)54 432 Q(CK Message)-.65
E F0(The)54 456 Q F1(NORM_ACK)2.5 E F0(message is intended to be used p\
rimarily as part of NORM congestion control operation and round-trip)2.5
E(timing measurement.)54 468 Q(As mentioned in the)5 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(message description, the ackno)2.5 E
(wledgement type)-.25 E F1(NORM_ACK_CC)54 480 Q F0(is pro)2.5 E
(vided for this purpose.)-.15 E(The generation of)5 E F1(NORM_ACK\(CC\))
2.5 E F0(messages for round-trip timing)2.5 E(estimation and congestion\
-control operation is described in Sections 5.5.1 and 5.5.2, respecti)54
492 Q -.15(ve)-.25 G(ly).15 E 5(.H)-.65 G -.25(ow)-5 G -2.15 -.25(ev e)
.25 H .8 -.4(r, s).25 H(ome multicast).4 E
(applications may bene\214t from some limited form of positi)54 504 Q .3
-.15(ve a)-.25 H(ckno).15 E(wledgement for certain functions.)-.25 E 2.5
(As)5 G(imple, scalable)-2.5 E(positi)54 516 Q .3 -.15(ve a)-.25 H(ckno)
.15 E(wledgement scheme is de\214ned in Section 5.5.3 that can be le)
-.25 E -.15(ve)-.25 G(raged by protocol implementations when).15 E 2.5
(appropriate. The)54 528 R F1(NORM_CMD\(FLUSH\))2.5 E F0
(may be used for OPTION)2.5 E(AL collection of positi)-.35 E .3 -.15
(ve a)-.25 H(ckno).15 E(wledgement of reliable)-.25 E
(reception to a certain "w)54 540 Q
(atermark" transmission point from speci\214c recei)-.1 E -.15(ve)-.25 G
(rs using this mechanism.).15 E(The NORM_A)5 E(CK type)-.4 E F1
(NORM_ACK_FLUSH)54 552 Q F0(is pro)2.5 E(vided for this purpose and the\
 format of the "nack_payload" for this ackno)-.15 E(wledgement type is)
-.25 E(gi)54 564 Q -.15(ve)-.25 G 2.5(nb).15 G(elo)-2.5 E 3.8 -.65(w. B)
-.25 H -.15(ey).65 G
(ond that, a range of application-de\214ned "ack_type" v).15 E
(alues is pro)-.25 E(vided for use at the NORM application')-.15 E(s)
-.55 E 2.5(discretion. Implementations)54 576 R
(making use of application-de\214ned positi)2.5 E .3 -.15(ve a)-.25 H
(ckno).15 E(wledgements may also mak)-.25 E 2.5(eu)-.1 G(se the)-2.5 E(\
"nack_payload" as needed, observing the constraint that the "nack_paylo\
ad" \214eld size be limited to a maximum of)54 588 Q(the)54 600 Q/F3 10
/Times-Italic@0 SF(NormSe)A(gmentSize)-.4 E F0
(for the sender to which the)2.5 E F1(NORM_ACK)2.5 E F0(is destined.)2.5
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q(|version| type=5|)109.2 120 Q 18(hdr_len |)24 F 72(sequence |)60 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 162(|s)109.2 144 S 156(ource_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
156 Q 162(|s)109.2 168 S 156(erver_id |)-162 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
180 Q 66(|s)109.2 192 S 54(ession_id |)-66 F 6(ack_type |)24 F 24
(ack_id |)30 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
204 Q 138(|g)109.2 216 S 132(rtt_response_sec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
228 Q 138(|g)109.2 240 S 126(rtt_response_usec |)-138 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
252 Q 90(|h)109.2 264 S(eader extensions \(if applicable\))-90 E(|)90 E
180(|.)109.2 276 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
288 Q 114(|a)109.2 300 S(ck_payload \(if applicable\))-114 E(|)102 E 180
(|.)109.2 312 S 174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
324 Q/F2 10/Times-Italic@0 SF(NORM_A)243.59 348 Q(CK Messa)-.3 E .2 -.1
(ge F)-.1 H(ormat)-.95 E F0
(The NORM common message header \214elds serv)54 372 Q 2.5(et)-.15 G
(heir usual purposes.)-2.5 E(The "serv)54 396 Q(er_id", "session_id",)
-.15 E(and "grtt_response" \214elds serv)5 E 2.5(et)-.15 G
(he same purpose as the corresponding \214elds in)-2.5 E F1(NORM_NACK)
2.5 E F0 2.5(messages. And)54 408 R(header e)2.5 E(xtensions may be app\
lied to support congestion control feedback or other functions in the s\
ame)-.15 E(manner)54 420 Q(.)-.55 E
(The "ack_type" \214eld indicates the nature of the)54 444 Q F1
(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)54 456 Q F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(message to which this ackno)2.5 E
(wledgement applies.)-.25 E(The "ack_id" \214eld serv)54 480 Q
(es as a sequence number so that the sender can v)-.15 E(erify that a)
-.15 E F1(NORM_ACK)2.5 E F0(message recei)2.5 E -.15(ve)-.25 G 2.5(da)
.15 G(ctually)-2.5 E(applies to a current ackno)54 492 Q
(wledgement request.)-.25 E
(The "ack_id" \214eld is not used in the case of the)5 E F1(NORM_ACK_CC)
2.5 E F0(and)2.5 E F1(NORM_ACK_FLUSH)54 504 Q F0(ackno)2.5 E
(wledgement types.)-.25 E
(The "ack_payload" format is a function of the "ack_type".)54 528 Q(The)
7.5 E F1(NORM_ACK_CC)2.5 E F0(message has no attached content.)2.5 E
(Only the)5 E F1(NORM_ACK)54 540 Q F0(header applies.)2.5 E
(In the case of)5 E F1(NORM_ACK_FLUSH)2.5 E F0 2.5(,as)C
(peci\214c "ack_payload" format is de\214ned:)-2.5 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Courier@0 SF 114(0123)124.2 84 S 6
(01234567890123456789012345678901)118.2 96 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
108 Q 30(|f)109.2 120 S 18(ec_id |)-30 F 18(reserved |)18 F 30
(object_transport_id |)36 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
132 Q 144(|f)109.2 144 S 144(ec_payload_id |)-144 F 180(|.)109.2 156 S
174(.. |)-180 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)109.2
168 Q/F2 10/Times-Italic@0 SF(NORM_A)213.28 192 Q(CK_FLUSH "ac)-.3 E
(k_payload" F)-.2 E(ormat)-1.05 E F0
(The "object_transport_id" and "fec_payload_id" are used by the recei)54
216 Q -.15(ve)-.25 G 2.5(rt).15 G 2.5(oa)-2.5 G(ckno)-2.5 E
(wledge applicable)-.25 E F1(NORM_CMD\(FLUSH\))2.5 E F0
(messages transmitted by the sender identi\214ed by the "serv)54 228 Q
(er_id" \214eld.)-.15 E(The "ack_payload" of)54 252 Q F1(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)54 264 Q F2(NormSe)2.5 E(gmentSize)-.4
E F0(of the sender referenced by the "serv)2.5 E(er_id".)-.15 E/F3 10
/Times-Bold@0 SF(4.4 General Messages)36 288 Q/F4 10/Times-BoldItalic@0
SF(4.4.1 NORM_REPOR)54 312 Q(T)-.3 E F0
(This is an optional message generated by NORM participants.)54 336 Q
(This message could be used for periodic performance reports)5 E
(from recei)54 348 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)54 360 Q 2.5(Tf)-.6 G
(ormats as needed for test purposes.)-2.5 E(These report messages)5 E
(SHOULD be disabled for interoperability testing between dif)54 372 Q
(ferent NORM implementations.)-.25 E F3(5.0 Functionality De\214nition)
36 396 Q F0
(This section describes the detailed interactions of senders and recei)
54 420 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)54 432 Q -.15
(ve)-.25 G 2.5(ni).15 G 2.5(nt)-2.5 G(he follo)-2.5 E(wing:)-.25 E(1\))
54 462 Q(The sender periodically transmits)77.33 462 Q F1
(NORM_CMD\(CC\))2.5 E F0
(messages as needed to initialize and collect roundtrip)2.5 E
(timing and congestion control feedback from the recei)77.33 474 Q -.15
(ve)-.25 G 2.5(rs).15 G(et.)-2.5 E(2\))54 498 Q
(The sender transmits an ordinal set of)77.33 498 Q F2(NormObjects)2.5 E
F0(se)2.5 E(gmented in the form of)-.15 E F1(NORM_DATA)2.5 E F0
(messages)2.5 E(labeled with)77.33 510 Q F2(NormT)2.5 E -.15(ra)-.55 G
(nsportIds).15 E F0
(and logically identi\214ed with FEC encoding block numbers and symbol)
2.5 E(identi\214ers.)77.33 522 Q F1(NORM_INFO)5 E F0(messages may optio\
nally precede the transmission of data content for NORM)2.5 E
(transport objects.)77.33 534 Q(3\))54 558 Q(As recei)77.33 558 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 F1
(NORM_NACK)2.5 E F0 2.5(messages. Note)77.33 570 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 F2
(objectId::fecP)2.5 E(ayloadId)-.8 E F0(transmit position and)2.5 E -.35
(NA)77.33 582 S
(CK _only_ for content ordinally prior to that transmit position.)-.05 E
(The recei)5 E -.15(ve)-.25 G(rs schedule random back).15 E(of)-.1 E(f)
-.25 E(timeouts before generating)77.33 594 Q F1(NORM_NACK)2.5 E F0
(messages and w)2.5 E
(ait an appropriate amount of time before repeating)-.1 E(the)77.33 606
Q F1(NORM_NACK)2.5 E F0(if their repair request is not satisi\214ed.)2.5
E(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(4\))54 84 Q(The sender aggre)77.33 84 Q -.05(ga)
-.15 G(tes repair requests from the recei).05 E -.15(ve)-.25 G
(rs and logically "re).15 E(winds" its transmit position to)-.25 E
(send appropriate repair messages.)77.33 96 Q(The sender sends repairs \
for the earliest ordinal transmit position \214rst)5 E
(and maintains this ordinal repair transmission sequence.)77.33 108 Q
(Pre)5 E(viously untransmitted FEC parity content for)-.25 E(the applic\
able FEC coding block is used for repair transmissions to the greatest \
e)77.33 120 Q(xtent possible.)-.15 E(If the)5 E(sender e)77.33 132 Q
(xhausts its a)-.15 E -.25(va)-.2 G
(ilable FEC parity content on multiple repair c).25 E
(ycles for the same coding block, it)-.15 E(resorts to an e)77.33 144 Q
(xplicit repair strate)-.15 E
(gy \(possibly using parity content\) to complete repairs.)-.15 E
(\(The use of e)5 E(xplicit)-.15 E(repair is e)77.33 156 Q
(xpected to be an e)-.15 E(xception in general protocol operation, b)
-.15 E(ut the possibility does e)-.2 E(xist for e)-.15 E(xtreme)-.15 E
2.5(conditions\). The)77.33 168 R
(sender immediately assumes transmission of ne)2.5 E 2.5(wc)-.25 G
(ontent once it has sent pending repairs.)-2.5 E(5\))54 192 Q
(The sender transmits)77.33 192 Q/F1 10/Courier@0 SF(NORM_CMD\(FLUSH\))
2.5 E F0(messages when it reaches the end of enqueued transmit)2.5 E 2.5
(content. Recei)77.33 204 R -.15(ve)-.25 G(rs respond to the).15 E F1
(NORM_CMD\(FLUSH\))2.5 E F0(messages with)2.5 E F1(NORM_NACK)2.5 E F0
(transmissions)2.5 E(\(follo)77.33 216 Q(wing the same suppression back)
-.25 E(of)-.1 E 2.5(ft)-.25 G(imeout strate)-2.5 E
(gy as for data\) if the)-.15 E 2.5(yr)-.15 G(equire further repair)-2.5
E(.)-.55 E(6\))54 240 Q(The sender transmissions are subject to rate co\
ntrol limits determined by congestion control.)77.33 240 Q(In the)5 E
(baseline NORM-CC operation, each sender in a)77.33 252 Q/F2 10
/Times-Italic@0 SF(NormSession)2.5 E F0(maintains its o)2.5 E
(wn independent congestion)-.25 E(control state.)77.33 264 Q(Recei)5 E
-.15(ve)-.25 G(rs pro).15 E(vide congestion control feedback in)-.15 E
F1(NORM_NACK)2.5 E F0(and)2.5 E F1(NORM_ACK)2.5 E F0(messages.)2.5 E F1
(NORM_ACK)77.33 276 Q F0(feedback for congestion control purposes is go)
2.5 E -.15(ve)-.15 G(rned using a suppression mechanism similar).15 E
(to that for)77.33 288 Q F1(NORM_NACK)2.5 E F0(messages.)2.5 E
(While the o)54 318 Q -.15(ve)-.15 G
(rall concept of the NORM protocol is relati).15 E -.15(ve)-.25 G
(ly simple, there are details to each of these aspects that need to).15
E(be addressed for successful, ef)54 330 Q(\214cient, rob)-.25 E
(ust, and scalable operation.)-.2 E/F3 10/Times-Bold@0 SF
(5.1 NORM Sender Initialization and T)36 354 Q(ransmission)-.74 E F0
(Upon startup, the NORM sender immediately be)54 378 Q(gins sending)-.15
E F1(NORM_CMD\(CC\))2.5 E F0(messages to collect round trip timing and)
2.5 E(other information from the potential group.)54 390 Q
(If NORM-CC congestion control operation is enabled, the NORM-CC Rate)5
E(header e)54 402 Q(xtension MUST be included in these messages.)-.15 E
(Congestion control operation SHALL be observ)5 E(ed at all times when)
-.15 E(operating in the general Internet.)54 414 Q(Ev)7.5 E
(en if congestion control operation is disabled at the sender)-.15 E 2.5
(,i)-.4 G 2.5(tm)-2.5 G(ay be desirable to use)-2.5 E(the)54 426 Q F1
(NORM_CMD\(CC\))2.5 E F0(messaging to collect feedback from the group u\
sing the baseline NORM-CC feedback mechanisms.)2.5 E(This proacti)54 438
Q .3 -.15(ve f)-.25 H(eedback collection can be used to establish GR).15
E(TT measurement prior to data transmission and potential)-.6 E -.35(NA)
54 450 S(CK operation.)-.05 E(In some cases, applications may wish for \
the sender to also proceed with data transmission immediately)54 474 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)54 486 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)54 498 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.)54 510 Q
(As noted, the periodic transmission of)5 E F1(NORM_CMD\(CC\))2.5 E F0
(messages may)2.5 E(precede actual data transmission in order to ha)54
522 Q .3 -.15(ve i)-.2 H(nitial GR).15 E(TT measurement.)-.6 E -.4(Wi)54
546 S(th inclusion of the OPTION).4 E(AL NORM FEC Object T)-.35 E
(ransmission Information Header Extension, the NORM protocol)-.35 E(sen\
der message headers can contain all information necessary to prepare re\
cei)54 558 Q -.15(ve)-.25 G(rs for subsequent reliable reception.).15 E
(This)5 E(includes FEC coding parameters, the sender)54 570 Q F2(NormSe)
2.5 E(gmentSize)-.4 E F0 2.5(,a)C(nd other information.)-2.5 E
(If this header e)5 E(xtension is not used, it)-.15 E
(is presumed that recei)54 582 Q -.15(ve)-.25 G(rs ha).15 E .3 -.15
(ve b)-.2 H(een properly pre-con\214gured via other means.).15 E
(Additionally)7.5 E 2.5(,a)-.65 G(pplications may le)-2.5 E -.15(ve)-.25
G(rage the).15 E(use of)54 594 Q F1(NORM_INFO)2.5 E F0(messages associa\
ted with the session data objects in the session to pro)2.5 E
(vide application-speci\214c conte)-.15 E(xt)-.15 E
(information for the session and data being transmitted.)54 606 Q
(These mechanisms allo)5 E 2.5(wf)-.25 G(or operation with minimal pre-)
-2.5 E(coordination among the senders and recei)54 618 Q -.15(ve)-.25 G
(rs.).15 E(The NORM sender be)54 642 Q(gins se)-.15 E
(gmenting application-enqueued data into)-.15 E F1(NORM_DATA)2.5 E F0
(se)2.5 E(gments and transmitting it to the)-.15 E 2.5(group. The)54 654
R(rate of transmission is controlled via congestion control mechanisms \
or at a \214x)2.5 E(ed rate if desired for closed)-.15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(netw)54 84 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 sender as needed.)-.15 E(When the)5 E
(sender reaches the end of data it has enqueued for transmission or an)
54 96 Q 2.5(yp)-.15 G(ending repairs, it transmits a series of)-2.5 E/F1
10/Courier@0 SF(NORM_CMD\(FLUSH\))54 108 Q F0
(messages at a rate of one per)2.5 E F1(2*GRTT)2.5 E F0 5(.R)C(ecei)-5 E
-.15(ve)-.25 G(rs may respond to these).15 E F1(NORM_CMD\(FLUSH\))2.5 E
F0(messages with additional repair requests.)54 120 Q 2.5(Ap)5 G
(rotocol parameter ")-2.5 E F1(NORM_ROBUST_FACTOR)A F0 2.5("d)C
(etermines the number of \215ush)-2.5 E(messages sent.)54 132 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 the end of repair transmission.)-.05 E
(The sender may attach an OPTION)54 144 Q(AL "acking_node_list" to)-.35
E F1(NORM_CMD\(FLUSH\))2.5 E F0(containing the)2.5 E/F2 10
/Times-Italic@0 SF(NormNodeIds)2.5 E F0(for)2.5 E(recei)54 156 Q -.15
(ve)-.25 G(rs from which it e).15 E(xpects e)-.15 E(xplicit positi)-.15
E .3 -.15(ve a)-.25 H(ckno).15 E(wledgement of reception.)-.25 E(The)5 E
F1(NORM_CMD\(FLUSH\))2.5 E F0(message may be)2.5 E
(also used for this optional function an)54 168 Q 2.5(yt)-.15 G
(ime prior to the end of data enqueued for transmission with the)-2.5 E
F1(NORM_CMD\(FLUSH\))54 180 Q F0(messages multiple)2.5 E -.15(xe)-.15 G
2.5(dw).15 G(ith ongoing data transmissions.)-2.5 E(The OPTION)5 E
(AL NORM positi)-.35 E -.15(ve)-.25 G(ackno)54 192 Q
(wledgement procedure is described in Section 5.5.3.)-.25 E/F3 10
/Times-Bold@0 SF(5.2 NORM Recei)36 216 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)54 240 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)54 252 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)54 264 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)54 276 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.)54 288 Q(The NORM sender implementation may \
wish to impose additional constraints to limit the ability of)5 E(recei)
54 300 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)54 312
Q(ferent applications and/or scenarios.)-.25 E -.15(Fo)5 G 2.5(rg).15 G
(eneral purpose operation, def)-2.5 E(ault polic)-.1 E(y)-.15 E
(where recei)54 324 Q -.15(ve)-.25 G(rs are allo).15 E
(wed to request repair only for coding blocks with a)-.25 E F2(NormT)2.5
E -.15(ra)-.55 G(nsportId).15 E F0(and FEC coding block number)2.5 E
(greater than or equal to the \214rst non-repair)54 336 Q F1(NORM_DATA)
2.5 E F0(or)2.5 E F1(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)-2.5 E 2.5(RECOMMENDED. F)54 348
R(or objects of type)-.15 E F1(NORM_OBJECT_STREAM)2.5 E F0
(it is RECOMMENDED that the join polic)2.5 E 2.5(yc)-.15 G(onstrain)-2.5
E(recei)54 360 Q -.15(ve)-.25 G(rs to start reliable reception at the c\
urrent FEC coding block for which non-repair content is recei).15 E -.15
(ve)-.25 G(d.).15 E F3(5.3 NORM Recei)36 384 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)54 408 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)54 420 S(CKing procedure SHALL be\
 initiated _only_ at FEC coding block boundaries,)-.05 E F2(NormObject)
2.5 E F0(boundaries, and upon receipt)2.5 E(of a)54 432 Q F1
(NORM_CMD\(FLUSH\))2.5 E F0(message.)2.5 E(The N)54 456 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("RandomBack)54 468 Q(of)-.1
E(f" algorithm described in the NORM Building Block document [15] using\
 \()-.25 E F1(K*GRTTsender)A F0 2.5(\)f)C(or the)-2.5 E("maxT)54 480 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)54 492 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)54 504 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
(operation.)54 516 Q(Thus:)54 540 Q F1
(T_backoff = RandomBackoff\(K*GRTTsender, GSIZEsender\))148.2 564 Q F0
1.6 -.8(To a)54 588 T -.2(vo).6 G(id the possibility of N).2 E -.4(AC)
-.35 G 2.5(Ki).4 G(mplosion in the case of sender or netw)-2.5 E(ork f)
-.1 E(ailure during SSM operation, the recei)-.1 E -.15(ve)-.25 G(r).15
E(SHALL automatically suppress its N)54 600 Q -.4(AC)-.35 G 2.5(Ka).4 G
(nd immediately enter the "holdof)-2.5 E(f" period described belo)-.25 E
2.5(ww)-.25 G(hen)-2.5 E F1(T_backoffis greater than \(K-1\)*GRTT)54 612
Q F0 5(.O)C(therwise, the back)-5 E(of)-.1 E 2.5(fp)-.25 G
(eriod is entered and the recei)-2.5 E -.15(ve)-.25 G 2.5(rM).15 G(UST)
-2.5 E(accumulate e)54 624 Q(xternal pending repair state from)-.15 E F1
(NORM_NACK)2.5 E F0(messages and)2.5 E F1(NORM_CMD\(REPAIR_ADV\))2.5 E
F0(messages recei)2.5 E -.15(ve)-.25 G(d.).15 E(At the end of the back)
54 636 Q(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)2.5 E F0
(message only if the follo)2.5 E(wing conditions are)-.25 E(met:)54 648
Q(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 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
(June 2003)185.175 E(1\))54 84 Q(The sender')77.33 84 Q 2.5(sc)-.55 G
(urrent transmit position \(in terms of)-2.5 E/F1 10/Times-Italic@0 SF
(objectId::fecP)2.5 E(ayloadId)-.8 E F0 2.5(\)e)C
(xceeds the earliest repair)-2.65 E(position of the recei)77.33 96 Q
-.15(ve)-.25 G -.55(r.).15 G(2\))54 120 Q
(The repair state accumulated from)77.33 120 Q/F2 10/Courier@0 SF
(NORM_NACK)2.5 E F0(and)2.5 E F2(NORM_CMD\(REPAIR_ADV\))2.5 E F0
(messages do not equal)2.5 E(or supersede the recei)77.33 132 Q -.15(ve)
-.25 G(r').15 E 2.5(sr)-.55 G
(epair needs up to the sender transmission position at the time the N)
-2.5 E -.4(AC)-.35 G(K).4 E(procedure \(back)77.33 144 Q(of)-.1 E 2.5
(ft)-.25 G(imeout\) w)-2.5 E(as initiated.)-.1 E
(If these conditions are met, the recei)54 174 Q -.15(ve)-.25 G 2.5(ri)
.15 G(mmediately generates a)-2.5 E F2(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(Otherwise, the recei)54 186 Q -.15(ve)-.25 G(r').15 E
2.5(sN)-.55 G -.4(AC)-2.85 G 2.5(Ki).4 G 2.5(sc)-2.5 G
(onsidered to be "suppressed" and the message is not sent.)-2.5 E
(At this time, the recei)5 E -.15(ve)-.25 G(r).15 E(be)54 198 Q
(gins a "holdof)-.15 E
(f" period during which it constrains itself to not reinitiate the N)
-.25 E -.4(AC)-.35 G(King process.).4 E(The purpose of this)5 E
(timeout is to allo)54 210 Q 2.5(wt)-.25 G(he sender w)-2.5 E
(orst-case time to respond to the repair needs before the recei)-.1 E
-.15(ve)-.25 G 2.5(rr).15 G(equests repair ag)-2.5 E 2.5(ain. The)-.05 F
-.25(va)54 222 S(lue of this "holdof).25 E(f" timeout)-.25 E(\()5 E F2
(T_rcvrHoldoff)A F0 2.5(\)a)C 2.5(sd)-2.5 G(escribed in [15] is:)-2.5 E
F2(T_rcvrHoldoff =\(K+2\)*GRTTsender)211.2 246 Q F0(The)54 270 Q F2
(NORM_NACK)2.5 E F0(message contains repair request content be)2.5 E
(ginning with lo)-.15 E(west ordinal repair position of the recei)-.25 E
-.15(ve)-.25 G 2.5(ru).15 G(p)-2.5 E(through the coding block prior to \
the most recently heard ordinal transmission position for the sender)54
282 Q 5(.I)-.55 G 2.5(ft)-5 G(he size of the)-2.5 E F2(NORM_NACK)54 294
Q F0(content e)2.5 E(xceeds the sender')-.15 E(s)-.55 E F1(NormSe)2.5 E
(gmentSize)-.4 E F0 2.5(,t)C(he N)-2.5 E -.4(AC)-.35 G 2.5(Kc).4 G
(ontent is truncated so that the recei)-2.5 E -.15(ve)-.25 G 2.5(ro).15
G(nly)-2.5 E(generates a single)54 306 Q F2(NORM_NACK)2.5 E 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 5(.I)-.55 G 2.5(ns)-5 G(ummary)
-2.5 E 2.5(,as)-.65 G(ingle N)-2.5 E -.4(AC)-.35 G 2.5(Km).4 G
(essage is)-2.5 E(generated containing the recei)54 318 Q -.15(ve)-.25 G
(r').15 E 2.5(sl)-.55 G -.25(ow)-2.5 G(est ordinal repair needs.).25 E
-.15(Fo)54 342 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)54 354 Q
(ginning with the lo)-.15 E(west ordinal _parity_ "encoding_symbol_id")
-.25 E(\(i.e. "encoding_symbol_id" = "source_block_len"\) and request t\
he number of FEC symbols corresponding to its data)54 366 Q(se)54 378 Q
(gment erasure count for the block.)-.15 E(On _subsequent_ repair c)5 E
(ycles for the same coding block, the recei)-.15 E -.15(ve)-.25 G 2.5
(rS).15 G(HALL request)-2.5 E
(only those repair symbols from the \214rst set it has not yet recei)54
390 Q -.15(ve)-.25 G 2.5(du).15 G 2.5(pt)-2.5 G 2.5(ot)-2.5 G
(he remaining erasure count for that applicable)-2.5 E(coding block.)54
402 Q(Note that the sender may ha)5 E .3 -.15(ve p)-.2 H(ro).15 E
(vided other dif)-.15 E(ferent, additional parity se)-.25 E
(gments for other recei)-.15 E -.15(ve)-.25 G(rs that).15 E
(could also be used to satisfy the local recei)54 414 Q -.15(ve)-.25 G
(r').15 E 2.5(se)-.55 G(rasure-\214lling needs.)-2.5 E
(In the case where the erasure count for a partially-)5 E(recei)54 426 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 from the sender for the block \(as).25 E(indicated by the)54 438
Q F2(NORM_DATA)2.5 E F0("fec_num_parity" \214eld\), the recei)2.5 E -.15
(ve)-.25 G 2.5(rS).15 G(HALL request all a)-2.5 E -.25(va)-.2 G
(ilable parity se).25 E(gments plus the)-.15 E
(ordinally highest missing data se)54 450 Q
(gments required to satisfy its total erasure needs for the block.)-.15
E(The goal of this strate)5 E(gy is)-.15 E(for the o)54 462 Q -.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 gi)-.25 E
-.15(ve)-.25 G 2.5(nF).15 G(EC coding block.)-2.5 E(This allo)54 474 Q
(ws the sender to construct the most ef)-.25 E
(\214cient repair transmission se)-.25 E(gment set and enables ef)-.15 E
(fecti)-.25 E .3 -.15(ve N)-.25 H -.4(AC)-.2 G(K).4 E
(suppression among the recei)54 486 Q -.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 synchronization among)5 E(the recei)54
498 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
522 S 2.5(rF).15 G(EC coding blocks or)-2.5 E F1(NormObjects)2.5 E F0
(missed 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 F2
(NORM_NACK_BLOCK)54 534 Q F0(or)2.5 E F2(NORM_NACK_OBJECT)2.5 E F0
(\215ags set as appropriate.)2.5 E(The request for retransmission of)5 E
F2(NORM_INFO)2.5 E F0(is)2.5 E(accomplished by setting the)54 546 Q F2
(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)36 570 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)54 594 Q 2.5(ef)-.1 G(orw)
-2.5 E
(ard progress in the transmission of data its application has enqueued.)
-.1 E(Ho)54 606 Q(we)-.25 E -.15(ve)-.25 G .8 -.4(r, t).15 H
(he sender must occasionally "re).4 E(wind" its logical transmission po\
int to satisfy the repair needs of recei)-.25 E -.15(ve)-.25 G(rs who)
.15 E(ha)54 618 Q .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 multiple N).05 E -.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)54 630 Q -.15(ve)-.25 G(rs initiate the N).15 E -.4(AC)-.35
G 2.5(Kp).4 G
(rocess on coding block or object boundaries, there is some loose de)
-2.5 E(gree of)-.15 E(synchronization of the repair process e)54 642 Q
-.15(ve)-.25 G 2.5(nw).15 G(hen recei)-2.5 E -.15(ve)-.25 G(rs e).15 E
(xperience uncorrelated data loss.)-.15 E(Adamson, Bormann, et al.)36
696 Q(Expires December 2003)105.89 E([P)119.09 E(age 39])-.15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Times-BoldItalic@0 SF
(5.4.1 NORM Sender Repair State Aggregation)54 84 Q F0
(When a sender is in its normal state of transmitting ne)54 108 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
120 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)
54 132 Q 2.5(wd)-.25 G(ata.)-2.5 E
(As described in [15], the period of time during which the sender aggre)
54 156 Q -.05(ga)-.15 G(tes).05 E F2(NORM_NACK)2.5 E F0
(messages is equal to:)2.5 E F2(T_sndrAggregate = \(K+1\)*GRTT)220.2 180
Q F0(where ")54 204 Q F2(K)A F0 2.5("i)C 2.5(st)-2.5 G(he same back)-2.5
E(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)-2.5 E(group')54 216 Q 2.5(sg)-.55 G
(reatest round-trip time.)-2.5 E(When this period ends, the sender "re)
54 240 Q(winds" by incorporating the accumulated repair state into its \
pending transmission state)-.25 E(and be)54 252 Q
(gins transmitting repair messages.)-.15 E(After pending repair transmi\
ssions are completed, the sender continues with ne)5 E(w)-.25 E
(transmissions of an)54 264 Q 2.5(ye)-.15 G(nqueued data.)-2.5 E
(Also, at this point in time, the sender be)5 E(gins a "holdof)-.15 E
(f" timeout during which time the)-.25 E
(sender constrains itself from initiating a ne)54 276 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(.A).15 G 2.5(sd)-5 G(escribed)-2.5 E(in [15], the v)54
288 Q(alue of this sender "holdof)-.25 E(f" period is:)-.25 E F2
(T_sndrHoldoff = \(1*GRTT\))232.2 312 Q F0(If additional)54 336 Q F2
(NORM_NACK)2.5 E F0(messages are recei)2.5 E -.15(ve)-.25 G 2.5(dd).15 G
(uring this sender "holdof)-2.5 E
(f" period, the sender will immediately)-.25 E(incorporate these "late \
messages" into its pending transmission state ONL)54 348 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)-2.5 E(sender')54 360 Q 2.5(sc)
-.55 G(urrent transmission position.)-2.5 E(This "holdof)5 E
(f" time allo)-.25 E(ws w)-.25 E
(orst case time for the sender to propag)-.1 E(ate its current)-.05 E
(transmission sequence position to the group, thus a)54 372 Q -.2(vo)-.2
G(iding redundant repair transmissions.).2 E(After the holdof)5 E 2.5
(ft)-.25 G(imeout)-2.5 E -.15(ex)54 384 S(pires, a ne).15 E 2.5(wN)-.25
G -.4(AC)-2.85 G 2.5(Ka).4 G(ccumulation period can be be)-2.5 E
(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).4 E(ne)54 396 Q
2.5(wd)-.25 G(ata transmission.)-2.5 E(Recall that recei)5 E -.15(ve)
-.25 G(rs are not to initiate the N).15 E -.4(AC)-.35 G 2.5(Kr).4 G
(epair process until the sender')-2.5 E 2.5(sl)-.55 G(ogical)-2.5 E
(transmission position e)54 408 Q(xceeds the lo)-.15 E
(west ordinal position of their repair needs.)-.25 E -.4(Wi)5 G
(th the ne).4 E 2.5(wN)-.25 G -.4(AC)-2.85 G 2.5(Ka).4 G(ggre)-2.5 E
-.05(ga)-.15 G(tion period, the).05 E(sender repeats the same process o\
f incorporating accumulated repair state into its transmission plan and\
 subsequently)54 420 Q("re)54 432 Q(winding" to transmit the lo)-.25 E
(west ordinal repair data when the aggre)-.25 E -.05(ga)-.15 G
(tion period e).05 E 2.5(xpires. Ag)-.15 F(ain, this is conducted in)
-.05 E(con)54 444 Q -.15(ve)-.4 G(rt with ongoing ne).15 E 2.5(wd)-.25 G
(ata and/or pending repair transmissions.)-2.5 E F1
(5.4.2 NORM Sender FEC Repair T)54 468 Q(ransmission Strategy)-.37 E F0
(The NORM sender should le)54 492 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)54 504 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)54 516 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 dif)-.15 E
(ferent recei)-.25 E -.15(ve)-.25 G(rs' repair needs, the).15 E
(sender can mak)54 528 Q 2.5(eu)-.1 G(se of the general erasure-\214lli\
ng capability of FEC-generated parity se)-2.5 E 2.5(gments. The)-.15 F
(sender can determine)2.5 E
(the maximum erasure \214lling needs for indi)54 540 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 2.5(dd).15 G(uring the)-2.5 E
(repair aggre)54 552 Q -.05(ga)-.15 G(tion period.).05 E
(Then, if the sender has a suf)5 E(\214cient number \(less than or equa\
l to the maximum erasure count\) of)-.25 E(pre)54 564 Q
(viously unsent parity se)-.25 E(gments a)-.15 E -.25(va)-.2 G(ilable f\
or the applicable coding blocks, the sender can transmit these in lieu \
of the).25 E(speci\214c pack)54 576 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 a)-.15 E(gi)54 588 Q -.15(ve)-.25 G 2.5(nc).15 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)
54 600 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)54 612 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)54 624 Q -.15(ve)-.25 G
2.5(nv).15 G(ery e)-2.65 E(xtreme circumstances.)-.15 E F2(NORM_DATA)54
648 Q F0(messages sent as repair transmissions are \215agged with the)
2.5 E F2(NORM_FLAG_REPAIR)2.5 E F0 2.5(\215ag. This)2.5 F(allo)2.5 E
(ws recei)-.25 E -.15(ve)-.25 G(rs).15 E(Adamson, Bormann, et al.)36 696
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(to obe)54 84 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(r\
s from joining the reliable transmission when only repair transmissions\
 ha).15 E .3 -.15(ve b)-.2 H(een).15 E(recei)54 96 Q -.15(ve)-.25 G(d.)
.15 E 1.6 -.8(To f)54 120 T(acilitate operation with Generic Router Ass\
ist \(GRA\) [12], the sender can additionally \215ag).7 E/F1 10
/Courier@0 SF(NORM_DATA)2.5 E F0(transmissions)2.5 E(sent as e)54 132 Q
(xplicit repair with the)-.15 E F1(NORM_FLAG_EXPLICIT)2.5 E F0 2.5
(\215ag. The)2.5 F(GRA router needs to only subcast a suf)2.5 E
(\214cient count of)-.25 E(non-e)54 144 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)54 156 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)54 168 Q -.15(ve)-.25 G 2.5(nc).15 G
(oding block.)-2.5 E(\(Note the GRA router will be required to conduct \
repair state accumulation)5 E
(for sub-routes in a manner similar to the sender')54 180 Q 2.5(sr)-.55
G(epair state accumulation in order to ha)-2.5 E .3 -.15(ve s)-.2 H(uf)
.15 E(\214cient information to perform)-.25 E(the subcasting.)54 192 Q
(Additionally)5 E 2.5(,t)-.65 G(he GRA router can perform additional)
-2.5 E F1(NORM_NACK)2.5 E F0(suppression/aggre)2.5 E -.05(ga)-.15 G
(tion as it conducts).05 E
(this repair state accumulation for NORM repair c)54 204 Q(ycles\).)-.15
E/F2 10/Times-BoldItalic@0 SF(5.4.3 NORM Sender NORM_CMD\(SQ)54 228 Q
(UELCH\) Generation)-.1 E F0(If the sender recei)54 252 Q -.15(ve)-.25 G
2.5(sa).15 G F1(NORM_NACK)A F0(message for repair of data it is no long\
er supporting, the sender generates a)2.5 E F1(NORM_CMD\(SQUELCH\))54
264 Q F0(message to adv)2.5 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)54 276 Q -.25
(va)-.4 G(lid data.).25 E(The transmission rate of)5 E F1
(NORM_CMD\(SQUELCH\))2.5 E F0(messages is limited to once per)2.5 E F1
(2*GRTT)2.5 E F0 5(.T)C(he)-5 E("in)54 288 Q -.25(va)-.4 G
(lid_object_list" \(if applicable\) of the).25 E F1(NORM_CMD\(SQUELCH\))
2.5 E F0(message SHALL be)2.5 E(gin with the lo)-.15 E(west)-.25 E
("object_transport_id" from the in)54 300 Q -.25(va)-.4 G(lid).25 E F1
(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 F1(NORM_CMD\(SQUELCH\))2.5 E F0(transmission.)2.5
E(Lo)54 312 Q(wer ordinal in)-.25 E -.25(va)-.4 G
(lid "object_transport_ids" should be included only while the).25 E F1
(NORM_CMD\(SQUELCH\))2.5 E F0(payload is less)2.5 E(than the sender')54
324 Q(s)-.55 E/F3 10/Times-Italic@0 SF(NormSe)2.5 E(gmentSize)-.4 E F0
(parameter)2.5 E(.)-.55 E F2(5.4.4 NORM Sender NORM_CMD\(REP)54 348 Q
(AIR_AD)-.85 E(V\) Generation)-.5 E F0(When a NORM sender recei)54 372 Q
-.15(ve)-.25 G(s).15 E F1(NORM_NACK)2.5 E F0(messages from recei)2.5 E
-.15(ve)-.25 G(rs via unicast transmission, it uses).15 E F1
(NORM_CMD\(REPAIR_ADV\))54 384 Q F0(messages to adv)2.5 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)-2.5 E
(not directly sharing their repair needs via multicast communication.)54
396 Q(The)5 E F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0(message is multicast)
2.5 E(to the recei)54 408 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 this message\
 has content in the same format as the)-5 E F1(NORM_NACK)2.5 E F0(recei)
54 420 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 suppression in the \
same manner as with).15 E F1(NORM_NACK)54 432 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)54 444 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 F1
(NORM_CMD\(REPAIR_ADV\))54 456 Q F0
(messages are subject to the sender transmit rate limit and)2.5 E F3
(NormSe)2.5 E(gmentSize)-.4 E F0 2.5(limitation. When)2.5 F(the)54 468 Q
F1(NORM_CMD\(REPAIR_ADV\))2.5 E F0(message is of maximum size, recei)2.5
E -.15(ve)-.25 G(rs SHALL consider the maximum ordinal).15 E
(transmission position v)54 480 Q(alue embedded in the message as the s\
enders "current" transmission position and implicitly suppress)-.25 E
(requests for ordinally higher repair)54 492 Q 5(.F)-.55 G
(or congestion control operation, the sender may also need to pro)-5.15
E(vide information so)-.15 E(that dynamic congestion control feedback c\
an be suppressed as needed among the recei)54 504 Q -.15(ve)-.25 G 2.5
(rs. This).15 F(document speci\214cies the)2.5 E(NORM-CC Feedback Heade\
r Extension that is applied for baseline NORM-CC operation.)54 516 Q
(If other congestion control)5 E
(mechanisms are used within a NORM implementation, other header e)54 528
Q(xtensions may be de\214ned.)-.15 E(Whate)5 E -.15(ve)-.25 G 2.5(rc).15
G(ontent format is)-2.5 E(used for this purpose should ensure that maxi\
mum possible suppression state is con)54 540 Q -.15(vey)-.4 G
(ed to the recei).15 E -.15(ve)-.25 G 2.5(rs).15 G(et.)-2.5 E/F4 10
/Times-Bold@0 SF(5.5 Additional NORM Pr)36 564 Q(otocol Mechanisms)-.18
E F0(In addition to the principal function of data content transmission\
 and repair)54 588 Q 2.5(,t)-.4 G
(here are some other protocol mechanisms that)-2.5 E
(help NORM to adapt to netw)54 600 Q(ork conditions and play f)-.1 E
(airly with other coe)-.1 E(xistent protocols.)-.15 E F2
(5.5.1 NORM Greatest Round-trip T)54 624 Q(ime \(GR)-.37 E
(TT\) Collection)-.3 E F0 -.15(Fo)54 648 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(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(participants must agree on a common timeout basis.)
54 84 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 \(GR)54 96 Q 2.5
(TT\). 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)54 108 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)54 120 Q/F1 10/Courier@0 SF(NORM_CMD\(CC\))2.5 E F0
(messages that contain a locally generated timestamp.)2.5 E(Recei)5 E
-.15(ve)-.25 G(rs are e).15 E(xpected to record)-.15 E
(this timestamp along with the time the)54 132 Q F1(NORM_CMD\(CC\))2.5 E
F0(message is recei)2.5 E -.15(ve)-.25 G 2.5(d. Then,).15 F
(when the recei)2.5 E -.15(ve)-.25 G(rs generate feedback).15 E
(messages to the sender)54 144 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 \()
-.15 E F1(NORM_NACK)A F0(or)2.5 E F1(NORM_ACK)54 156 Q F0 2.5(\). 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 its response.)-2.5 E(Upon)
5 E(receipt of this adjusted timestamp, the sender is able to calculate\
 the round-trip time to that recei)54 168 Q -.15(ve)-.25 G -.55(r.).15 G
(The round-trip time for each recei)54 192 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
(of the GR)54 204 Q(TT)-.6 E 5(.T)-.74 G(he algorithm and methodology a\
re described in the NORM Building Block document [11] in the section)-5
E(entitled "One-to-Man)54 216 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)54 228 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.)54 240 Q(The adv)5 E(ertised GR)-.15 E
(TT is also limited to a minimum of the nominal inter)-.6 E(-pack)-.2 E
(et transmission time gi)-.1 E -.15(ve)-.25 G(n).15 E(the sender')54 252
Q 2.5(sc)-.55 G(urrent transmission rate and system clock granularity)
-2.5 E 5(.T)-.65 G(he reason for this additional limit is to k)-5 E
(eep the)-.1 E(recei)54 264 Q -.15(ve)-.25 G 2.5(rs).15 G(ome)-2.5 E
(what "e)-.25 E -.15(ve)-.25 G(nt dri).15 E -.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)-2.5 E(requests from recei)54 276 Q -.15
(ve)-.25 G(rs gi).15 E -.15(ve)-.25 G 2.5(nt).15 G
(ransmit rate limitations due to congestion control or con\214guration.)
-2.5 E(When the NORM-CC Rate header e)54 300 Q(xtension is present in)
-.15 E F1(NORM_CMD\(CC\))2.5 E F0(messages, the recei)2.5 E -.15(ve)-.25
G(rs respond to).15 E F1(NORM_CMD\(CC\))54 312 Q F0(messages as describ\
ed in Section 5.5.2, "NORM Congestion Control Operation".)2.5 E(The)5 E
F1(NORM_CMD\(CC\))2.5 E F0(messages are periodically generated by the s\
ender as described for congestion control operation.)54 324 Q(This pro)5
E(vides for)-.15 E(proacti)54 336 Q -.15(ve)-.25 G 2.5(,b).15 G
(ut controlled, feedback from the group in the form of)-2.7 E F1
(NORM_ACK)2.5 E F0 2.5(messages. This)2.5 F(pro)2.5 E(vides for GR)-.15
E(TT feedback)-.6 E -2.15 -.25(ev e)54 348 T 2.5(ni).25 G 2.5(fn)-2.5 G
(o)-2.5 E F1(NORM_NACK)2.5 E F0(messages are being sent.)2.5 E
(If operating without congestion control in a closed netw)5 E(ork, the)
-.1 E F1(NORM_CMD\(CC\))54 360 Q F0
(messages may be sent periodically without the NORM-CC Rate header e)2.5
E 2.5(xtension. In)-.15 F(this case, recei)2.5 E -.15(ve)-.25 G(rs).15 E
(will only pro)54 372 Q(vide GR)-.15 E(TT measurement feedback when)-.6
E F1(NORM_NACK)2.5 E F0(messages are generated since no)2.5 E F1
(NORM_ACK)2.5 E F0(messages)2.5 E(are generatedR.)54 384 Q
(In this case, the)5 E F1(NORM_CMD\(CC\))2.5 E F0
(messages may be sent less frequently)2.5 E 2.5(,p)-.65 G
(erhaps as little as once per)-2.5 E(minute, to conserv)54 396 Q 2.5(en)
-.15 G(etw)-2.5 E(ork capacity)-.1 E 5(.N)-.65 G
(ote that the NORM-CC Rate header e)-5 E
(xtension may also be used proacti)-.15 E -.15(ve)-.25 G(ly solicit).15
E -.6(RT)54 408 S 2.5(Tf).6 G(eedback from the recei)-2.5 E -.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 conducting)-2.5 E
(congestion control rate adjustment.)54 420 Q(NORM operation without co\
ngestion control should be considered only in closed)5 E(netw)54 432 Q
(orks.)-.1 E/F2 10/Times-BoldItalic@0 SF 5(5.5.2 NORM)54 456 R
(Congestion Control Operation \(NORM-CC\))2.5 E F0(This section describ\
es baseline congestion control operation for the NORM protocol \(NORM-C\
C\).)54 480 Q(This congestion control)5 E(scheme is REQ)54 492 Q(UIRED \
for operation within the general Internet unless the NORM implementatio\
n is adapted to use another)-.1 E(IETF-sanctioned reliable multicast co\
ngestion control mechanism \(e.g. PGMCC\).)54 504 Q
(The supporting NORM message formats)5 E(and approach described here ar\
e an adaptation of the equation-based TCP-Friendly Multicast Congestion\
 Control \(TFMCC\))54 516 Q(approach described in [18] and [21].)54 528
Q -.4(Wi)5 G(th this TFMCC-based approach, the transmissions of NORM se\
nders are controlled).4 E(in a rate-based manner as opposed to windo)54
540 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 2.5
(sp)-2.5 G(ossible that)-2.5 E
(the NORM protocol message set may alternati)54 552 Q -.15(ve)-.25 G
(ly be used to support a windo).15 E
(w-based multicast congestion control scheme)-.25 E(such as PGMCC [22].)
54 564 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 this document.)-.25 E(In)5 E
(either case \(rate-based TFMCC or windo)54 576 Q(w-based PGMCC\), succ\
essful control of sender transmission depends upon)-.25 E
(collection of sender)54 588 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 control bottleneck)-3.1 E(pa\
th\(s\) within the multicast topology and adjust the sender rate accord\
ingly)54 600 Q 5(.T)-.65 G(he recei)-5 E -.15(ve)-.25 G 2.5(rw).15 G
(ith loss and R)-2.5 E(TT estimates that)-.6 E(correspond to the lo)54
612 Q(west result transmission rate is identi\214ed as the "current lim\
iting recei)-.25 E -.15(ve)-.25 G(r" \(CLR\).).15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(As described in [23], a steady-state sender transm\
ission rate, to be "friendly" with competing TCP \215o)54 84 Q
(ws can be calculated)-.25 E(as:)54 96 Q/F1 10/Courier@0 SF(S)288 120 Q
(Rsender = ------------------------------------------------------------\
---)54 132 Q(tRTT * \(sqrt\(\(2/3\)*p\) + 12 * sqrt\(\(3/8\)*p\) * p * \
\(1 + 32*\(p^2\)\)\))114 144 Q F0(where)54 168 Q F1(S)72 198 Q F0(=)2.5
E(Nominal transmitted pack)91.14 198 Q
(et size. \(In NORM, the "nominal" pack)-.1 E
(et size can be determined by the sender as)-.1 E(an e)91.14 210 Q
(xponentially 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\).)91.14 222 Q F1(tRTT)54 246 Q F0(=)2.5 E
(The R)91.14 246 Q(TT estimate of the current "current limiting recei)
-.6 E -.15(ve)-.25 G(r" \(CLR\).).15 E F1(p)72 270 Q F0(=)2.5 E
(The loss e)91.14 270 Q -.15(ve)-.25 G(nt fraction of the CLR.).15 E 1.6
-.8(To s)54 300 T(upport congestion control feedback collection and ope\
ration, the NORM sender periodically transmits).8 E F1(NORM_CMD\(CC\))
2.5 E F0(command messages.)54 312 Q
(NORM_CMD\(CC\) messages are multiple)5 E -.15(xe)-.15 G 2.5(dw).15 G
(ith NORM data and repair transmissions and serv)-2.5 E(e)-.15 E(se)54
324 Q -.15(ve)-.25 G(ral purposes:).15 E(1\))54 354 Q(Stimulate e)67.33
354 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
378 Q(Communicate state to the recei)67.33 378 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.)
67.33 390 Q(3\))54 414 Q(Initiate rapid \(immediate\) feedback from the\
 CLR in order to closely track the dynamics of congestion)67.33 414 Q
(control for that "w)67.33 426 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)54 456 Q F1(NORM_CMD\(CC\))2.5 E F0
(message is describe in Section 4.2.3 of this document.)2.5 E(The)5 E F1
(NORM_CMD\(CC\))2.5 E F0(message)2.5 E(contains information to allo)54
468 Q 2.5(wd)-.25 G(etermination of sender<->recei)-2.5 E -.15(ve)-.25 G
2.5(rR).15 G(TTs, to inform the group of the congestion control CLR,)
-3.1 E(and to pro)54 480 Q(vide feedback of indi)-.15 E(vidual R)-.25 E
(TT information to the recei)-.6 E -.15(ve)-.25 G(rs in the group.).15 E
(The)5 E F1(NORM_CMD\(CC\))2.5 E F0(also pro)2.5 E(vides)-.15 E(for e)54
492 Q(xciting feedback from OPTION)-.15 E(AL "potential limiting recei)
-.35 E -.15(ve)-.25 G
(r" \(PLR\) nodes that may be determined administrati).15 E -.15(ve)-.25
G(ly).15 E
(or possibly algorithmically based on congestion control feedback.)54
504 Q(PLR nodes are recei)5 E -.15(ve)-.25 G(rs that ha).15 E .3 -.15
(ve b)-.2 H(een identi\214ed to ha).15 E -.15(ve)-.2 G(potential for \(\
perhaps soon\) becoming the CLR and thus immediate, up-to-date feedback\
 is bene\214cial for congestion control)54 516 Q(performance. The detai\
ls of PLR selection are not discussed in this document.)54 528 Q/F2 10
/Times-BoldItalic@0 SF 2.5(5.5.2.1 NORM_CMD\(CC\))54 552 R -.37(Tr)2.5 G
(ansmission).37 E F0(The)54 576 Q F1(NORM_CMD\(CC\))2.5 E F0(message is\
 transmitted periodically by the sender along with its normal data tran\
smission.)2.5 E(Note that)5 E(the repeated transmission of)54 588 Q F1
(NORM_CMD\(CC\))2.5 E F0(messages may be initiated some time before tra\
nsmission of user data content)2.5 E(at session startup.)54 600 Q(This \
may be done to collect some estimation of the current state of the mult\
icast topology with respect to)5 E(group and indi)54 612 Q(vidual R)-.25
E(TT and congestion control state.)-.6 E(A)54 636 Q F1(NORM_CMD\(CC\))
2.5 E F0(message is immediately transmitted at sender startup.)2.5 E
(The interv)5 E(al of subsequent)-.25 E F1(NORM_CMD\(CC\))2.5 E F0
(message transmission is determined as follo)54 648 Q(ws:)-.25 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(1\))54 84 Q(By def)67.33 84 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 96 Q
-.15(ve)-.25 G 2.5(df).15 G(rom the group.)-2.5 E(2\))54 120 Q
(If a CLR has been identi\214ed \(based on pre)67.33 120 Q(vious recei)
-.25 E -.15(ve)-.25 G 2.5(rf).15 G(eedback\), the interv)-2.5 E
(al is the sender<->recei)-.25 E -.15(ve)-.25 G(r).15 E -.6(RT)67.33 132
S 2.5(Tf).6 G(or the CLR.)-2.5 E(3\))54 156 Q(Additionally)67.33 156 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 R)-.6 E(TT_clr)-.6 E(interv)67.33 168 Q(al, the)-.25 E/F1 10
/Courier@0 SF(NORM_CMD\(CC\))2.5 E F0(interv)2.5 E
(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)67.33 180 Q
(xclusion of user data transmission.)-.15 E(The)54 210 Q F1
(NORM_CMD\(CC\))2.5 E F0
("cc_sequence" \214eld is incremented with each transmission of a)2.5 E
F1(NORM_CMD\(CC\))2.5 E F0 2.5(command. The)2.5 F
(greatest "cc_sequence" recently recei)54 222 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)54 234 Q -.2
(vo)-.2 G(idance.).2 E
(The NORM-CC Rate Header Extension is applied to the)54 258 Q F1
(NORM_CMD\(CC\))2.5 E F0(message and the sender adv)2.5 E
(ertises its current)-.15 E
(transmission rate in the "send_rate" \214eld.)54 270 Q
(The rate information is used by recei)5 E -.15(ve)-.25 G
(rs to initialize loss estimation during).15 E
(congestion control startup or restart.)54 282 Q
(The "cc_node_list" contains a list of entries identifying recei)54 306
Q -.15(ve)-.25 G
(rs and their current congestion control state \(status "\215ags",).15 E
("rtt" and "loss" estimates\).)54 318 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)54 330 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(NORM_FLAG_CC_CLR)2.5 E F0(\215ag)2.5 E -.25(va)54 342 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)-2.5 E
(the list for implementation ef)54 354 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)
54 366 Q -.15(ve)-.25 G(rs in the group.).15 E(The number of additional\
 entries in this list is dependent upon the percentage of control)5 E
(traf)54 378 Q(\214c the sender application is willing to send with res\
pect to user data message transmissions.)-.25 E
(More entries in the list may)5 E(allo)54 390 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)54 402 Q F1
(NORM_CMD\(CC\))2.5 E F0 2.5(messages. The)2.5 F(maximum length)2.5 E
(of the list corresponds to the sender')54 414 Q(s)-.55 E/F2 10
/Times-Italic@0 SF(NormSe)2.5 E(gmentSize)-.4 E F0
(parameter for the session.)2.5 E
(The inclusion of additional entries in the)5 E(list based on recei)54
426 Q -.15(ve)-.25 G 2.5(rf).15 G(eedback are prioritized with follo)
-2.5 E(wing rules:)-.25 E(1\))54 456 Q(Recei)67.33 456 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)67.33 468 Q .3
-.15(ve p)-.25 H(recedence for list inclusion.).15 E(2\))54 492 Q
(Secondly)67.33 492 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 recei)-.6 E -.15(ve)-.25 G
(rs yielding the lo).15 E(west)-.25 E
(calculated congestion rate getting precedence.)67.33 504 Q
(There are "cc_\215ag" v)54 534 Q(alues in addition to)-.25 E F1
(NORM_FLAG_CC_CLR)2.5 E F0
(that are used for other congestion control functions.)2.5 E(The)5 E F1
(NORM_FLAG_CC_PLR)54 546 Q F0(\215ag v)2.5 E
(alue is used to mark additional recei)-.25 E -.15(ve)-.25 G
(rs from that 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,)2.7 E(non-suppressed feedback.)54 558
Q(These may be recei)5 E -.15(ve)-.25 G(rs that the sender algorithmica\
lly identi\214ed as potential future CLRs or that).15 E(ha)54 570 Q .3
-.15(ve b)-.2 H(een pre-con\214gured as potential congestion control po\
ints in the netw).15 E 2.5(ork. The)-.1 F F1(NORM_FLAG_CC_RTT)2.5 E F0
(indicates the)2.5 E -.25(va)54 582 S
(lidity 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 be set since the recei)-2.5 E -.15(ve)-.25 G
(rs in the list will).15 E(typically be recei)54 594 Q -.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 case that the NORM sender has been)-2.5 E
(pre-con\214gured with a set of PLR nodes, feedback from those recei)54
606 Q -.15(ve)-.25 G(rs may not yet ha).15 E .3 -.15(ve b)-.2 H
(een collected and thus the "cc_rtt").15 E
(and "cc_rate" \214elds do not contain v)54 618 Q(alid v)-.25 E
(alues when this \215ag is not set.)-.25 E(Adamson, Bormann, et al.)36
696 Q(Expires December 2003)105.89 E([P)119.09 E(age 44])-.15 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Times-BoldItalic@0 SF 2.5
(5.5.2.2 NORM_CMD\(CC\))54 84 R -1(Fe)2.5 G(edbac)1 E 2.5(kR)-.1 G
(esponse)-2.5 E F0(Recei)54 108 Q -.15(ve)-.25 G(rs e).15 E
(xplicitly respond to)-.15 E/F2 10/Courier@0 SF(NORM_CMD\(CC\))2.5 E F0
(messages in the form of a)2.5 E F2(NORM_ACK)2.5 E F0(\(R)A
(TT\) message.)-.6 E(The goal of the)5 E
(congestion control feedback is to determine the recei)54 120 Q -.15(ve)
-.25 G(rs with the lo).15 E(west congestion control rates.)-.25 E(Recei)
5 E -.15(ve)-.25 G(rs that are mark).15 E(ed)-.1 E
(as CLR or PLR nodes in the)54 132 Q F2(NORM_CMD\(CC\))2.5 E F0
("cc_node_list" immediately pro)2.5 E(vide feedback in the form of a)
-.15 E F2(NORM_ACK)2.5 E F0(to)2.5 E(this message.)54 144 Q(When a)5 E
F2(NORM_CMD\(CC\))2.5 E F0(is recei)2.5 E -.15(ve)-.25 G
(d, non-CLR or non-PLR nodes initiate random feedback back).15 E(of)-.1
E 2.5(ft)-.25 G(imeouts)-2.5 E(similar to that used when the recei)54
156 Q -.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 data loss.)-.15 E
(The)5 E(back)54 168 Q(of)-.1 E 2.5(ft)-.25 G
(imeout for the congestion control response is generated as follo)-2.5 E
(ws:)-.25 E F2(T_backoff = RandomBackoff\(K*GRTTsender, GSIZEsender\))
148.2 192 Q F0(The ")54 216 Q F2(RandomBackoff\(\))A F0 2.5("a)C
(lgorithm pro)-2.5 E(vides a truncated e)-.15 E(xponentially distrib)
-.15 E(uted random number and is described in)-.2 E
(the NORM Building Block document [11].)54 228 Q(The same back)5 E(of)
-.1 E 2.5(ff)-.25 G(actor "K" is used with the GR)-2.6 E(TT as with)-.6
E F2(NORM_NACK)2.5 E F0 2.5(suppression. As)54 240 R(pre)2.5 E
(viously noted, a v)-.25 E(alue of)-.25 E F2 6(K=4)2.5 G F0
(is generally recommended for ASM operation and)-3.5 E F2 6(K=6)2.5 G F0
(for SSM)-3.5 E 2.5(operation. A)54 252 R(recei)2.5 E -.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 F2(NORM_ACK)2.5 E
F0(\(R)A(TT\) message)-.6 E(under the follo)54 264 Q(wing conditions:)
-.25 E(1\))54 294 Q(The recei)67.33 294 Q -.15(ve)-.25 G 2.5(rg).15 G
(enerates another feedback message \()-2.5 E F2(NORM_NACK)A F0(or other)
2.5 E F2(NORM_ACK)2.5 E F0 2.5(\)b)C(efore the)-2.5 E
(congestion control feedback timeout e)67.33 306 Q(xpires,)-.15 E(2\))54
330 Q(A)67.33 330 Q F2(NORM_CMD\(CC\))2.5 E F0(or other recei)2.5 E -.15
(ve)-.25 G 2.5(rf).15 G
(eedback with an ordinally greater "cc_sequence" \214eld v)-2.5 E
(alue is)-.25 E(recei)67.33 342 Q -.15(ve)-.25 G 2.5(db).15 G
(efore the congestion control feedback timeout e)-2.5 E
(xpires \(This is similar to the TFMCC feedback)-.15 E(round number\),)
67.33 354 Q(3\))54 378 Q(When the)67.33 378 Q F2(T_backoff)2.5 E F0
(is greater than)2.5 E F2(1*GRTT)2.5 E F0 5(.T)C(his pre)-5 E -.15(ve)
-.25 G(nts N).15 E -.4(AC)-.35 G 2.5(Ki).4 G(mplosion in the e)-2.5 E
-.15(ve)-.25 G(nt of sender or).15 E(netw)67.33 390 Q(ork f)-.1 E
(ailure.)-.1 E(4\))54 414 Q
("Suppressing" congestion control feedback is heard from another recei)
67.33 414 Q -.15(ve)-.25 G 2.5(r\().15 G(in a)-2.5 E F2(NORM_ACK)2.5 E
F0(or)2.5 E F2(NORM_NACK)67.33 426 Q F0 2.5(\)o)C 2.5(rv)-2.5 G(ia a)
-2.5 E F2(NORM_CMD\(REPAIR_ADV\))2.5 E F0(message from the sender)2.5 E
5(.T)-.55 G(he local recei)-5 E -.15(ve)-.25 G(r').15 E(s)-.55 E(feedba\
ck is "suppressed" if the rate of the competing feedback \(Rfb\) is suf)
67.33 438 Q(\214ciently close to or less than the)-.25 E(local recei)
67.33 450 Q -.15(ve)-.25 G(r').15 E 2.5(sc)-.55 G
(alculated rate \(Rcalc\).)-2.5 E(The local recei)5 E -.15(ve)-.25 G(r')
.15 E 2.5(sf)-.55 G(eedback is canceled when:)-2.5 E F2
(Rcalc > \(0.9 * Rfb\))226.33 474 Q F0(Also note recei)67.33 498 Q -.15
(ve)-.25 G(rs that ha).15 E .3 -.15(ve n)-.2 H(ot yet recei).15 E -.15
(ve)-.25 G 2.5(da).15 G 2.5(nR)-2.5 G
(TT measurement from the sender are suppressed only by)-3.1 E
(other recei)67.33 510 Q -.15(ve)-.25 G(rs that ha).15 E .3 -.15(ve n)
-.2 H(ot yet measured R).15 E(TT)-.6 E 5(.A)-.74 G(dditionally)-5 E 2.5
(,r)-.65 G(ecei)-2.5 E -.15(ve)-.25 G(rs whose R).15 E
(TT estimate has "aged")-.6 E(considerably \(i.e. the)67.33 522 Q 2.5
(yh)-.15 G -2.25 -.2(av e)-2.5 H(n').2 E 2.5(tb)-.18 G
(een included in the NORM_CMD\(CC\) "cc_node_list" in a long time\) may)
-2.5 E(wish to compete as a recei)67.33 534 Q -.15(ve)-.25 G 2.5(rw).15
G(ith no prior R)-2.5 E(TT measurement after some e)-.6 E
(xpiration period.)-.15 E(When the back)54 564 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(rS).15 G
(HALL generate a)-2.5 E F2(NORM_ACK\(RTT\))2.5 E F0(message to pro)2.5 E
(vide feedback to the)-.15 E(sender and group.)54 576 Q
(This message may be multicast to the group for most ef)5 E(fecti)-.25 E
.3 -.15(ve s)-.25 H(uppression in ASM topologies or unicast).15 E
(to the sender depending upon ho)54 588 Q 2.5(wt)-.25 G
(he NORM protocol is deplo)-2.5 E(yed and con\214gured.)-.1 E(Whene)54
612 Q -.15(ve)-.25 G 2.5(ra).15 G .3 -.15(ny f)-2.5 H
(eedback is generated \(including this).15 E F2(NORM_ACK\(RTT\))2.5 E F0
(message\), recei)2.5 E -.15(ve)-.25 G(rs include an adjusted v).15 E
(ersion of)-.15 E(the sender timestamp from the most recently recei)54
624 Q -.15(ve)-.25 G(d).15 E F2(NORM_CMD\(CC\))2.5 E F0
(message and the "cc_sequence" v)2.5 E(alue from that)-.25 E
(command in the applicable)54 636 Q F2(NORM_ACK)2.5 E F0(or)2.5 E F2
(NORM_NACK)2.5 E F0(message \214elds.)2.5 E -.15(Fo)5 G 2.5(rN).15 G
(ORM-CC operation, an)-2.5 E 2.5(yg)-.15 G(enerated feedback)-2.5 E
(message SHALL also contain the NORM-CC Feedback header e)54 648 Q 2.5
(xtension. The)-.15 F(recei)2.5 E -.15(ve)-.25 G 2.5(rp).15 G(ro)-2.5 E
(vides its current "cc_rate")-.15 E(Adamson, Bormann, et al.)36 696 Q
(Expires December 2003)105.89 E([P)119.09 E(age 45])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(estimate, "cc_loss" estimate, "cc_rtt" if kno)54 84
Q(wn, and an)-.25 E 2.5(ya)-.15 G
(pplicable "cc_\215ags" via this header e)-2.5 E(xtension.)-.15 E
(During)54 108 Q/F1 10/Times-Italic@0 SF(slow start)2.5 E F0
(\(when the recei)2.5 E -.15(ve)-.25 G 2.5(rh).15 G
(as not yet detected loss from the sender\), 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.)54 120 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)54 132 S
(lue is from 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(\(The)5 E(GR)54 144 Q
(TT is used when the recei)-.6 E -.15(ve)-.25 G 2.5(rh).15 G
(as not yet measured its indi)-2.5 E(vidual R)-.25 E(TT\).)-.6 E
(The "cc_loss" \214eld v)54 168 Q(alue re\215ects the recei)-.25 E -.15
(ve)-.25 G(r').15 E 2.5(sc)-.55 G(urrent loss e)-2.5 E -.15(ve)-.25 G
(nt estimate with respect to the sender in question.).15 E
(When the recei)54 192 Q -.15(ve)-.25 G 2.5(rh).15 G(as a v)-2.5 E
(alid indi)-.25 E(vidual R)-.25 E
(TT measurement, it SHALL include this v)-.6 E
(alue in the "cc_rtt" \214eld.)-.25 E(The)5 E/F2 10/Courier@0 SF
(NORM_FLAG_CC_RTT)54 204 Q F0
(MUST be set when the "cc_rtt" \214eld is v)2.5 E(alid.)-.25 E(After a \
congestion control feedback message is generated or when the feedback i\
s suppressed, a non-CLR recei)54 240 Q -.15(ve)-.25 G 2.5(rb).15 G -.15
(eg)-2.5 G(ins a).15 E("holdof)54 252 Q
(f" timeout period during which it will restrain itself from pro)-.25 E
(viding congestion control feedback, e)-.15 E -.15(ve)-.25 G 2.5(ni).15
G(f)-2.5 E F2(NORM_CMD\(CC\))54 264 Q F0(messages are recei)2.5 E -.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)5 E
-.25(va)54 276 S(lue of this holdof).25 E 2.5(ft)-.25 G(imeout \()-2.5 E
F2(T_ccHoldoff)A F0 2.5(\)p)C(eriod is:)-2.5 E F2
(T_ccHoldoff = \(K*GRTT\))238.2 300 Q F0(Thus, non-CLR recei)54 324 Q
-.15(ve)-.25 G(rs are constrained to pro).15 E(viding e)-.15 E
(xplicit congestion control feedback once per)-.15 E F2(K*GRTT)2.5 E F0
(interv)2.5 E(als.)-.25 E(Note, ho)54 336 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 F2
(NORM_CMD\(CC\))2.5 E F0(messages)2.5 E(and there will be relati)54 348
Q -.15(ve)-.25 G(ly continuous feedback of congestion control informati\
on while the sender is acti).15 E -.15(ve)-.25 G(.).15 E/F3 10
/Times-BoldItalic@0 SF 2.5(5.5.2.3 Congestion)54 384 R
(Control Rate Adjustment)2.5 E F0(During steady-state operation, the se\
nder will directly adjust its transmission rate to the rate indicated b\
y the feedback from)54 408 Q(its currently selected CLR according to an)
54 420 Q 2.5(yl)-.15 G(imitations described in [18].)-2.5 E
(As noted there, the estimation of parameters \(loss)5 E(and R)54 432 Q
(TT\) 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)54 444 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
(The sender processes congestion control feedback from the recei)54 480
Q -.15(ve)-.25 G(rs and selects the CLR based on the lo).15 E
(west rate recei)-.25 E -.15(ve)-.25 G -.55(r.).15 G(Recei)54 492 Q -.15
(ve)-.25 G 2.5(rr).15 G(ates are either determined directly from the)
-2.5 E F1(slow start)2.5 E F0("cc_rate" pro)2.5 E(vided by the recei)
-.15 E -.15(ve)-.25 G 2.5(ri).15 G 2.5(nt)-2.5 G(he NORM-CC)-2.5 E
(Feedback header e)54 504 Q
(xtension or by performing the equation-based calculation using indi)
-.15 E(vidual R)-.25 E(TT and loss estimates)-.6 E
(\("cc_loss"\) as feedback is recei)54 516 Q -.15(ve)-.25 G(d.).15 E
(The sender can calculate a current R)54 540 Q(TT for a recei)-.6 E -.15
(ve)-.25 G 2.5(r\().15 G F2(RTT_rcvrNew)-2.5 E F0 2.5(\)u)C
(sing the "grtt_response" timestamp included in)-2.5 E
(feedback messages.)54 552 Q(When the "cc_rtt" v)5 E
(alue in a response is not v)-.25 E(alid, the sender simply uses this)
-.25 E F2(RTT_rcvrNew)2.5 E F0 -.25(va)2.5 G(lue as).25 E(the recei)54
564 Q -.15(ve)-.25 G(r').15 E 2.5(sc)-.55 G(urrent R)-2.5 E(TT \()-.6 E
F2(RTT_rcvr)A F0 2.5(\). F)B(or non-CLR and non-PLR recei)-.15 E -.15
(ve)-.25 G(rs, the sender can use the "cc_rtt" v).15 E(alue)-.25 E(pro)
54 576 Q(vided in the NORM-CC Feedback header e)-.15 E
(xtension as the recei)-.15 E -.15(ve)-.25 G(r').15 E 2.5(sp)-.55 G(re)
-2.5 E(vious R)-.25 E(TT measurement \()-.6 E F2(RTT_rcvrPrev)A F0 2.5
(\)t)C(o)-2.5 E(smooth according to:)54 588 Q F2
(RTT_rcvr = 0.5 * RTT_rcvrPrev + 0.5 * RTT_rcvrNew)157.2 612 Q F0 -.15
(Fo)54 636 S 2.5(rC).15 G(LR recei)-2.5 E -.15(ve)-.25 G
(rs where feedback is recei).15 E -.15(ve)-.25 G 2.5(dm).15 G(ore re)
-2.5 E(gularly)-.15 E 2.5(,t)-.65 G
(he sender SHOULD maintain a more smoothed R)-2.5 E(TT estimate)-.6 E
(upon ne)54 648 Q 2.5(wf)-.25 G(eedback from the CLR where:)-2.5 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 E(age 46])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Courier@0 SF
(RTT_clr = 0.9 * RTT_clr + 0.1 * RTT_clrNew)178.2 84 Q F0(")54 108 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(RTT_clr)54
120 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)54 132 Q -.15(ve)-.25 G(rs and that if a P\
LR is "promoted" to CLR status, the smoothed estimate can be continued.)
.15 E(There are some additional periods besides steady-state operation \
that need to be considered in NORM-CC operation.)54 156 Q(These)5 E
(periods are:)54 168 Q 25.17(1\) during)90 192 R(session startup,)2.5 E
25.17(2\) when)90 204 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)90 216 R
(the sender has a break in data transmission.)2.5 E
(During session startup, the congestion control operation SHALL observ)
54 240 Q 2.5(ea")-.15 G(slo)-2.5 E 2.5(ws)-.25 G
(tart" procedure to quickly approach its f)-2.5 E(air)-.1 E
(bandwidth share.)54 252 Q
(An initial sender startup rate is assumed where:)5 E F1(Rinitial = MIN\
\(NormSegmentSize / GRTT, NormSegmentSize\) bytes/second.)97.2 276 Q F0
(The rate is increased only when feedback is recei)54 300 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)54 312 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)5 E/F2 10/Times-Italic@0 SF(slow start)2.5 E F0
(is applied as:)2.5 E F1(Rnew = Rrecv_min)256.2 336 Q F0(where ")54 360
Q F1(Rrecv_min)A F0 2.5("i)C 2.5(st)-2.5 G(he minimum reported recei)
-2.5 E -.15(ve)-.25 G 2.5(rr).15 G
(ate in the "cc_rate" \214eld of congestion control feedback messages)
-2.5 E(recei)54 372 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 sender in the)-2.5 E
("cc_rate" \214eld of their feedback.)54 384 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)54 408 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_FLA).15 E(G_CC_LEA)-.4 E
(VE in its congestion control)-1.35 E(feedback message as an indication\
 that the sender should not select it as the CLR.)54 420 Q
(When the CLR changes to a lo)5 E(wer rate)-.25 E(recei)54 432 Q -.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 rate at one)5 E
(additional pack)54 444 Q(et per R)-.1 E(TT to)-.6 E -.1(wa)-.25 G
(rds an).1 E 2.5(yn)-.15 G -.25(ew)-2.5 G 2.5(,h)-.4 G(igher CLR rate.)
-2.5 E
(The sender should also track the "age" of the feedback it has recei)54
468 Q -.15(ve)-.25 G 2.5(df).15 G
(rom the CLR by comparing its current "cc_sequence")-2.5 E -.25(va)54
480 S(lue \(Seq_sender\) to the last "cc_sequence" v).25 E(alue recei)
-.25 E -.15(ve)-.25 G 2.5(df).15 G(rom the CLR \(Seq_clr\).)-2.5 E
(As the "age" of the CLR feedback)5 E(increases with no ne)54 492 Q 2.5
(wf)-.25 G(eedback, the sender SHALL be)-2.5 E
(gin reducing its rate once per)-.15 E F1(RTT_clr)2.5 E F0
(as a congestion a)2.5 E -.2(vo)-.2 G(idance).2 E 2.5(measure. The)54
504 R(follo)2.5 E(wing algorithm is used to determine the decrease in s\
ender rate \(Rsender bytes/sec\) as the CLR feedback,)-.25 E(une)54 516
Q(xpectedly)-.15 E 2.5(,e)-.65 G(xcessi)-2.65 E -.15(ve)-.25 G(ly ages:)
.15 E F1(Age = Seq_sender - Seq_clr;)54 540 Q
(if \(Age > 4\) Rsender = Rsender * 0.5;)54 552 Q F0
(This rate reduction is limited to the lo)54 576 Q
(wer bound on NORM transmission rate.)-.25 E(After)5 E F1
(NORM_ROBUST_FACTOR)2.5 E F0(consecuti)2.5 E -.15(ve)-.25 G F1
(NORM_CMD\(CC\))54 588 Q F0(rounds without an)2.5 E 2.5(yf)-.15 G(eedba\
ck from the CLR, the sender SHOULD assume the CLR has left the group an\
d)-2.5 E(pick the recei)54 600 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 not ha)2.5 E .3 -.15
(ve ex)-.2 H(plicit).15 E(kno)54 612 Q
(wledge that the CLR intentionally left the group.)-.25 E(If no recei)5
E -.15(ve)-.25 G 2.5(rf).15 G(eedback is recei)-2.5 E -.15(ve)-.25 G
(d, the sender MA).15 E 2.5(Yw)-1.05 G(ish to withold)-2.5 E
(further transmissions of)54 624 Q F1(NORM_DATA)2.5 E F0(se)2.5 E
(gements and maintain)-.15 E F1(NORM_CMD\(CC\))2.5 E F0
(transmissions only until feedback is)2.5 E 2.5(detected. After)54 636 R
(such a CLR timeout, the sender will be transmitting with a minimal rat\
e and should return to slo)2.5 E 2.5(ws)-.25 G(tart as)-2.5 E
(described here for a break in data transmission.)54 648 Q
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(When the sender has a break in its data transmissi\
on, it can continue to probe the group with)54 84 Q/F1 10/Courier@0 SF
(NORM_CMD\(CC\))2.5 E F0(messages to)2.5 E(maintain R)54 96 Q
(TT collection from the group.)-.6 E(This will enable the sender to qui\
ckly determine an appropriate CLR upon data)5 E(transmission restart.)54
108 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 restart as)-.18 E
(time since the break elapses.)54 120 Q(The tar)5 E
(get rate SHOULD be recalculated once per)-.18 E F1(RTT_clr)2.5 E F0
(as:)2.5 E F1(Rsender = Rsender * 0.5;)232.2 144 Q F0(If the minimum NO\
RM rate is reached, the sender should set the NORM_FLA)54 168 Q(G_ST)-.4
E(AR)-.93 E 2.5<548d>-.6 G(ag in its)-2.5 E F1(NORM_CMD\(CC\))2.5 E F0
(messages upon restart and the group should observ)54 180 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(r).15 E -.15(ex)54 192 S
(periences a ne).15 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)54 216 Q(ositiv)-.55 E 2.5
(eA)-.15 G -.1(ck)-2.5 G(no).1 E(wledgment Procedure)-.25 E F0(NORM pro)
54 240 Q(vides options 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\(FLUSH\))2.5 E F0(and)2.5 E F1(NORM_CMD\(ACK_REQ\))54 252 Q F0
(messages from members of the group.)2.5 E
(There are some speci\214c ackno)5 E(wledgement requests de\214ned)-.25
E(for the NORM protocol and a range of ackno)54 264 Q(wledgment request\
 types that are left to be de\214ned by the application.)-.25 E(One)5 E
(prede\214ned ackno)54 276 Q(wledgement type is the)-.25 E F1
(NORM_ACK_FLUSH)2.5 E F0 2.5(type. This)2.5 F(ackno)2.5 E
(wledgement is used to determine if recei)-.25 E -.15(ve)-.25 G(rs).15 E
(ha)54 288 Q .3 -.15(ve a)-.2 H(chie).15 E -.15(ve)-.25 G 2.5(dc).15 G(\
ompletion of reliable reception up through a speci\214c logical transmi\
ssion point with respect to the sender')-2.5 E(s)-.55 E
(sequence of transmission.)54 300 Q(The)5 E F1(NORM_ACK_FLUSH)2.5 E F0
(ackno)2.5 E(wledgement may be used to assist in application \215o)-.25
E 2.5(wc)-.25 G(ontrol)-2.5 E
(when the sender has information on a portion of the recei)54 312 Q -.15
(ve)-.25 G 2.5(rs).15 G 2.5(et. Another)-2.5 F(prede\214ned ackno)2.5 E
(wledgement type is)-.25 E F1(NORM_ACK\(CC\))54 324 Q F0 2.5(,w)C
(hich is used to e)-2.5 E(xplicitly pro)-.15 E
(vide congestion control feedback in response to)-.15 E F1
(NORM_CMD\(CC\))2.5 E F0
(messages transmitted by the sender for NORM-CC operation.)54 336 Q
(Note the)5 E F1(NORM_ACK\(CC\))2.5 E F0(response does NO)2.5 E 2.5(Tf)
-.4 G(ollo)-2.5 E 2.5(wt)-.25 G(he)-2.5 E(positi)54 348 Q .3 -.15(ve a)
-.25 H(ckno).15 E(wledgement procedure described here.)-.25 E(The)5 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(and)2.5 E F1(NORM_ACK)2.5 E F0
(messages contain an)2.5 E
("ack_type" \214eld to identify the type of ackno)54 360 Q
(wledgement requested and pro)-.25 E 2.5(vided. A)-.15 F
(range of "ack_type" v)2.5 E(alues is pro)-.25 E(vided)-.15 E
(for application-de\214ned use.)54 372 Q
(While the application is responsible for initiating the ackno)5 E
(wledgement request and interprets)-.25 E
(application-de\214ned "ack_type" v)54 384 Q(alues, the ackno)-.25 E
(wledgment procedure SHOULD be conducted within the protocol)-.25 E
(implementation to tak)54 396 Q 2.5(ea)-.1 G(dv)-2.5 E
(antage of timing and transmission scheduling information a)-.25 E -.25
(va)-.2 G(ilable to the NORM transport.).25 E(The NORM positi)54 420 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)5 E
(this polling procedure is not intended to scale to v)54 432 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 setting to query)-.18 E 2.5(ac)
54 444 S(ritical subset of the group.)-2.5 E(Either the)5 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0 2.5(,o)C 2.5(rw)-2.5 G
(hen applicable, the)-2.5 E F1(NORM_CMD\(FLUSH\))2.5 E F0(message)2.5 E
(is used for polling and contains a list of)54 456 Q/F3 10
/Times-Italic@0 SF(NormNodeIds)2.5 E F0(for recei)2.5 E -.15(ve)-.25 G
(rs that should respond to the command.).15 E(The list of)5 E(recei)54
468 Q -.15(ve)-.25 G(rs pro).15 E(viding ackno)-.15 E
(wledgement is determined by the source application with "a priori" kno)
-.25 E(wledge of participating)-.25 E
(nodes or via some other application-le)54 480 Q -.15(ve)-.25 G 2.5(lm)
.15 G(echanism.)-2.5 E(The A)54 504 Q
(CK process is initiated by the sender that generates)-.4 E F1
(NORM_CMD\(FLUSH\))2.5 E F0(or)2.5 E F1(NORM_CMD\(ACK_REQ\))2.5 E F0
(messages in)2.5 E(periodic "rounds".)54 516 Q -.15(Fo)5 G(r).15 E F1
(NORM_ACK_FLUSH)2.5 E F0(requests, the)2.5 E F1(NORM_CMD\(FLUSH\))2.5 E
F0(contain a "object_transport_id" and)2.5 E
("fec_payload_id" denoting the w)54 528 Q
(atermark transmission point for which ackno)-.1 E
(wledgement is requested.)-.25 E(This w)5 E(atermark)-.1 E
(transmission point is "echoed" in the corresponding \214elds of the)54
540 Q F1(NORM_ACK\(FLUSH\))2.5 E F0(message sent by the recei)2.5 E -.15
(ve)-.25 G 2.5(ri).15 G(n)-2.5 E(response.)54 552 Q F1
(NORM_CMD\(ACK_REQ\))5 E F0(messages contain an "ack_id" \214eld which \
is similarly "echoed" in response so that the)2.5 E
(sender may match the response to the appropriate request.)54 564 Q
(In response to the)54 600 Q F1(NORM_CMD\(ACK_REQ\))2.5 E F0 2.5(,t)C
(he listed recei)-2.5 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)54 612 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 5(.\()-.55 G
(Note that)-5 E F1(NORM_ACK\(CC\))2.5 E F0
(messages SHALL be multicast or unicast in the same manner as)54 624 Q
F1(NORM_NACK)2.5 E F0(messages\).)2.5 E(Adamson, Bormann, et al.)36 696
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E(The A)54 84 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
108 R 2.5(as)2.5 G(ingle)-2.5 E/F1 10/Courier@0 SF(NORM_CMD\(ACK_REQ\))
2.5 E F0(message is generated once per \(2*GR)2.5 E(TT\), and,)-.6 E
25.17(2\) The)90 132 R(size of the "acking_node_list" of)2.5 E/F2 10
/Times-Italic@0 SF(NormNodeIds)2.5 E F0(from which ackno)2.5 E
(wledgment is requested is limited to)-.25 E 2.5(am)126 144 S
(aximum of the sender)-2.5 E F2(NormSe)2.5 E(gmentSize)-.4 E F0
(setting per round of the positi)2.5 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')54 168
Q(s)-.55 E F2(NormSe)2.5 E(gmentSize)-.4 E F0(setting, multiple)2.5 E F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(rounds may be required to achie)54 180 Q
.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 attached)7.5 E F2(NormNodeId)
2.5 E F0(list will)2.5 E
(be dynamically updated as this process progresses and)54 192 Q F1
(NORM_ACK)2.5 E F0(responses are recei)2.5 E -.15(ve)-.25 G 2.5(df).15 G
(rom the speci\214ed recei)-2.5 E -.15(ve)-.25 G 2.5(rs).15 G(et.)-2.5 E
(As the sender recei)54 204 Q -.15(ve)-.25 G 2.5(sv).15 G
(alid responses \(i.e. matching w)-2.75 E
(atermark point or "ack_id"\) from recei)-.1 E -.15(ve)-.25 G
(rs, it SHALL eliminate those).15 E(recei)54 216 Q -.15(ve)-.25 G
(rs from the subsequent).15 E F1(NORM_CMD\(ACK_REQ\))2.5 E F0
(message "acking_node_list" and add in an)2.5 E 2.5(yp)-.15 G
(ending recei)-2.5 E -.15(ve)-.25 G(r).15 E F2(NormNodeIds)54 228 Q F0
(while k)2.5 E(eeping within the)-.1 E F2(NormSe)2.5 E(gmentSize)-.4 E
F0(limitation of the list size.)2.5 E(Each recei)5 E -.15(ve)-.25 G 2.5
(ri).15 G 5(sq)-2.5 G(ueried a maximum)-5 E(number of times \()54 240 Q
F1(NORM_ROBUST_FACTOR)A F0 2.5(,b)C 2.5(yd)-2.5 G(ef)-2.5 E 2.5
(ault\). Recei)-.1 F -.15(ve)-.25 G
(rs not responding within this number of repeated requests).15 E
(are remo)54 252 Q -.15(ve)-.15 G 2.5(df).15 G
(rom the payload list to mak)-2.5 E 2.5(er)-.1 G
(oom for other potential recei)-2.5 E -.15(ve)-.25 G(rs pending ackno)
.15 E 2.5(wledgement. The)-.25 F(transmission)2.5 E(of the)54 264 Q F1
(NORM_CMD\(ACK_REQ\))2.5 E F0(is repeated until no further responses ar\
e required or until the repeat threshold is e)2.5 E(xceeded)-.15 E
(for all pending recei)54 276 Q -.15(ve)-.25 G 2.5(rs. The).15 F
(transmission of)2.5 E F1(NORM_CMD\(ACK_REQ\))2.5 E F0(or)2.5 E F1
(NORM_CMD\(FLUSH\))2.5 E F0(messages to conduct the)2.5 E(positi)54 288
Q .3 -.15(ve a)-.25 H(ckno).15 E(wledgment process is multiple)-.25 E
-.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).4 E F1
(NORM_CMD\(FLUSH\))54 300 Q F0(positi)2.5 E .3 -.15(ve a)-.25 H(ckno).15
E(wledgment process may be interrupted in response to ne)-.25 E -.05(ga)
-.15 G(ti).05 E .3 -.15(ve a)-.25 H(ckno).15 E(wledgement repair)-.25 E
(requests \(N)54 312 Q -.4(AC)-.35 G(Ks\) recei).4 E -.15(ve)-.25 G 2.5
(df).15 G(rom recei)-2.5 E -.15(ve)-.25 G(rs during the ackno).15 E
(wledgment period.)-.25 E(The)5 E F1(NORM_CMD\(FLUSH\))2.5 E F0(positi)
2.5 E -.15(ve)-.25 G(ackno)54 324 Q
(wledgment process is restarted for recei)-.25 E -.15(ve)-.25 G
(rs pending ackno).15 E(wledgement once an)-.25 E 2.5(yt)-.15 G
(he repairs ha)-2.5 E .3 -.15(ve b)-.2 H(een transmitted.).15 E
(In the case of)54 348 Q F1(NORM_CMD\(FLUSH\))2.5 E F0
(commands with an attached "acking_node_list", recei)2.5 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)54 360 Q -.15(ve)-.25 G 2.5(dc).15 G
(omplete transmission of all data up to and including the gi)-2.5 E -.15
(ve)-.25 G 2.5(nw).15 G(atermark transmission point.)-2.6 E(All recei)5
E -.15(ve)-.25 G(rs).15 E(SHALL interpret the w)54 372 Q
(atermark point pro)-.1 E(vided in the request N)-.15 E -.4(AC)-.35 G
2.5(Kf).4 G(or repairs if needed as for)-2.5 E F1(NORM_CMD\(FLUSH\))2.5
E F0(commands with no attached "acking_node_list".)54 384 Q/F3 10
/Times-BoldItalic@0 SF(5.5.4 Group Size Estimation)54 408 Q F0(NORM sen\
der messages contain a "gsize" \214eld that is a representation of the \
group size and is used in scaling random)54 432 Q(back)54 444 Q(of)-.1 E
2.5(ft)-.25 G(imer ranges.)-2.5 E(The use of the group size estimate wi\
thin the NORM protocol does not require a precise estimation)5 E(and w)
54 456 Q(orks reasonably well if the estimate is within an order of mag\
nitude of the actual group size.)-.1 E(By def)5 E(ault, the NORM)-.1 E
(sender group size estimate may be administrati)54 468 Q -.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 of the NORM protocol)-.15 E
(for general use, a def)54 480 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)54 504 Q(olume of congestion control feedback messages)-.2 E
(which follo)54 516 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 currently).4 E(be)54 528 Q
(yond the scope of this document.)-.15 E F3
(5.5.5 Operation with Generic Router Assist \(GRA\))54 552 Q F0
(NORM pack)54 576 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 N)5 E -.4(AC)-.35 G(K).4 E(suppression and selecti)54 588 Q
.3 -.15(ve s)-.25 H(ub-casting of repair transmissions in the netw).15 E
(ork will be possible with GRA.)-.1 E(\(Section 5.4.2)5 E
(discusses some NORM mechanisms related to this\).)54 600 Q
(Additional details will be pro)5 E(vide in future v)-.15 E
(ersions of this document as)-.15 E(GRA speci\214cations mature.)54 612
Q(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Times-Bold@0 SF(6.0 Security Considerations)
36 84 Q F0(The same security considerations that apply to the NORM, FEC\
, and TFMCC)54 108 Q -.2(bu)5 G(ilding blocks also apply to the NORM).2
E 2.5(protocol. In)54 120 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 to, the)-2.5 E -.35(NA)54 132 S
(CK based feedback of NORM may be e)-.05 E(xploited by replay attacks w\
hich force the NORM sender to unnecessarily)-.15 E
(transmit repair information.)54 144 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 guard ag)-.1 E(ainst this)
-.05 E(potential security e)54 156 Q 2.5(xploitation. It)-.15 F
(is RECOMMENDED that such IP security mechanisms be used when a)2.5 E
-.25(va)-.2 G 2.5(ilable. Another).25 F(possible approach is for NORM s\
enders to use the "sequence" \214eld from the NORM Common Message Heade\
r to detect)54 168 Q(replay attacks.)54 180 Q(This can be accomplished \
if the sender is willing to maintain state on recei)5 E -.15(ve)-.25 G
(rs which are N).15 E -.4(AC)-.35 G 2.5(King. A).4 F(cache of recei)54
192 Q -.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 the "sequence" \214eld should be)5 E
(incremented with independent v)54 204 Q(alues for "sender" messages v)
-.25 E(ersus "recei)-.15 E -.15(ve)-.25 G
(r" messages so that the congestion control loss).15 E
(estimation function of the "sequence" \214eld can be preserv)54 216 Q
(ed for sender messages when recei)-.15 E -.15(ve)-.25 G 2.5(rm).15 G
(essages are unicast to the)-2.5 E(sender)54 228 Q(.)-.55 E
(While NORM does le)54 252 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)54 264 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].)54 288 Q F1(7.0 Suggested Use)36 312 Q F0
(The present NORM protocol is seen as useful tool for the)54 336 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 not)2.5 E
(the intention of the authors to suggest it is suitable for)54 348 Q
(supporting all en)5 E(visioned multicast reliability requirements.)-.4
E(NORM)5 E(pro)54 360 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(\214c implosion)-.25 E
(and protocol o)54 372 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 MBone for b).15
E(ulk)-.2 E(data dissemination applications, including weather satellit\
e compressed imagery updates servicing a lar)54 384 Q(ge group of recei)
-.18 E -.15(ve)-.25 G(rs).15 E
(and a generic web content reliable "push" application.)54 396 Q
(In addition, this frame)54 420 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)54 432 Q(ork applications.)-.1 E
(NORM is capable of successfully operating independent of netw)5 E
(ork structure and in)-.1 E(en)54 444 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.)54 456 Q 2.5(As)5 G
(ender)-2.5 E(-only repair approach often mak)-.2 E
(es additional engineering sense)-.1 E(in asymmetric netw)54 468 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 in)-.1 E(netw)54 480 Q
(orks where only unidirectional multicast routing/deli)-.1 E -.15(ve)
-.25 G(ry service e).15 E
(xists. Asymmetric architectures supporting multicast)-.15 E(deli)54 492
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 portion of the future Internet structure \
\(e.g., DBS/cable/PSTN h)-2.5 E(ybrids\) and)-.05 E(ef)54 504 Q
(\214cient, reliable b)-.25 E
(ulk data transfer will be an important capability for servicing lar)-.2
E(ge groups of subscribed recei)-.18 E -.15(ve)-.25 G(rs.).15 E F1
(8.0 Ackno)36 528 Q(wledgements \(and these ar)-.1 E 2.5(en)-.18 G
(ot Negati)-2.5 E -.1(ve)-.1 G(\)).1 E F0(The authors w)54 552 Q
(ould lik)-.1 E 2.5(et)-.1 G 2.5(ot)-2.5 G(hank Rick Jones, V)-2.5 E
(incent Roca, and Joer)-.6 E 2.5(gW)-.18 G(idmer for their v)-2.9 E
(aluable comments on this document.)-.25 E(The authors w)54 564 Q
(ould also lik)-.1 E 2.5(et)-.1 G 2.5(ot)-2.5 G(hank the RMT w)-2.5 E
(orking group chairs, Roger K)-.1 E(ermode and Lorenzo V)-.25 E
(icisano, for their)-.6 E(support in de)54 576 Q -.15(ve)-.25 G
(lopment of this speci\214cation, and Sally Flo).15 E
(yd for her early input into this document.)-.1 E
(Adamson, Bormann, et al.)36 696 Q(Expires December 2003)105.89 E
([P)119.09 E(age 50])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E/F1 10/Times-Bold@0 SF(9.0 Refer)36 84 Q(ences)-.18
E F0([1])59 114 Q -.25(Ke)122.398 114 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
126 Q([2])59 150 Q(Bradner)122.398 150 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.)122.398 162 Q
([3])59 186 Q(Mankin, A., Romano)122.398 186 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)122.398 198 S
(ansport and Application Protocols", RFC 2357, June 1998.).35 E([4])59
222 Q(Whetten, B., V)122.398 222 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)122.398 234 Q 2.5(yB)
-.15 G(ulk-Data T)-2.5 E(ransfer", RFC 3048, January 2001.)-.35 E([5])59
258 Q(Handle)122.398 258 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])59 282 Q(Handle)122.398 282 Q 1.3 -.65(y, M)-.15 H(., Perkin\
s, C. and E. Whelan, "Session Announcement Protocol", RFC 2974, October\
 2000.).65 E([7])59 306 Q(S. Ping)122.398 306 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.)122.398 318 Q([8])59
342 Q(Luby)122.398 342 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.)
122.398 354 Q([9])59 378 Q(J. Mack)122.398 378 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.)122.398 390 Q
([10])54 414 Q(J. Nonnenmacher and E. Biersack, "Optimal Multicast Feed\
back", Proc. IEEE INFOCOMM, p. 964,)122.398 414 Q(March/April 1998.)
122.398 426 Q([11])54 450 Q(J. Mack)122.398 450 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.)122.398 462 Q([12])54 486 Q 1.48
-.74(T. S)122.398 486 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,)122.398 498 Q -.1(wo)122.398 510 S
(rk in progress.).1 E(Citation for informational purposes only)5 E(.)
-.65 E([13])54 534 Q(Deering, S., "Host Extensions for IP Multicasting"\
, STD 5, RFC 1112, August 1989.)122.398 534 Q([14])54 558 Q
(Holbrook, H. W)122.398 558 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.)122.398 570 Q
([15])54 594 Q(B. Adamson, C. Bormann, M. Handle)122.398 594 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
(CK-Oriented Reliable Multicast \(NORM\))-.05 E(Protocol Building Block\
s", Internet Draft draft-ietf-rmt-bb-norm-05.txt, March 2003, w)122.398
606 Q(ork in progress.)-.1 E(Citation for informational purposes only)
122.398 618 Q(.)-.65 E(Adamson, Bormann, et al.)36 696 Q
(Expires December 2003)105.89 E([P)119.09 E(age 51])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
(June 2003)185.175 E([16])54 84 Q(M. Luby)122.398 84 Q 2.5(,L)-.65 G 2.5
(.V)-2.5 G(icisano, J. Gemmell, L. Rizzo, M. Handle)-3.1 E 1.3 -.65
(y, a)-.15 H(nd J. Cro).65 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 96 Q([17])54 120 Q(M. Luby)122.398 120 Q 2.5(,L)-.65 G 2.5(.V)
-2.5 G(icisano, J. Gemmell, L. Rizzo, M. Handle)-3.1 E 1.3 -.65(y, a)
-.15 H(nd J. Cro).65 E(wcroft, "F)-.25 E(orw)-.15 E
(ard Error Correction)-.1 E
(\(FEC\) Building BLock", RFC 3452, December 2002.)122.398 132 Q([18])54
156 Q(J. W)122.398 156 Q(idmer)-.4 E 2.5(,M)-.4 G 2.5(.H)-2.5 G(andle)
-2.5 E 1.3 -.65(y, ")-.15 H(TCP-Friendly Multicast Congestion Control \
\(TFMCC\) Protocol Speci\214cation",).65 E
(Internet Draft draft-ietf-rmt-bb-tfmcc-01.txt, No)122.398 168 Q -.15
(ve)-.15 G(mber 2002, w).15 E(ork in progress.)-.1 E
(Citation for informational)5 E(purposes only)122.398 180 Q(.)-.65 E
([19])54 204 Q(D. Gossink, J. Mack)122.398 204 Q(er)-.1 E 2.5(,")-.4 G
(Reliable Multicast and Inte)-2.5 E(grated P)-.15 E
(arity Retransmission with Channel Estimation",)-.15 E
(IEEE GLOBECOMM 98', September 1998.)122.398 216 Q([20])54 240 Q
(H. Schulzrinne, S. Casner)122.398 240 Q 2.5(,R)-.4 G 2.5(.F)-2.5 G
(rederick, V)-2.5 E 2.5(.J)-1.29 G(acobson, "R)-2.5 E(TP: A T)-.6 E
(ransport Protocol for Real-T)-.35 E(ime)-.35 E
(Applications", RFC 1889, January 1996.)122.398 252 Q([21])54 276 Q
(J. W)122.398 276 Q(idmer and M. Handle)-.4 E 1.3 -.65(y, ")-.15 H(Exte\
nding Equation-Based Congestion Control to Multicast Applications",).65
E(Proc A)122.398 288 Q(CM SIGCOMM 2001, San Die)-.4 E(go, August 2001.)
-.15 E([22])54 312 Q(L. Rizzo, "pgmcc: A TCP-Friendly Single-Rate Multi\
cast Congestion Control Scheme", Proc A)122.398 312 Q(CM)-.4 E
(SIGCOMM 2000, Stockholm, August 2000.)122.398 324 Q([23])54 348 Q(S. K)
122.398 348 Q(ent and R. Atkinson, "Security Architecture for the Inter\
net Protocol", RFC 2401, No)-.25 E -.15(ve)-.15 G(mber 1998.).15 E([23])
54 372 Q(J. P)122.398 372 Q(adh)-.15 E(ye, V)-.05 E 2.5(.F)-1.29 G
(iroiu, D. T)-2.5 E -.25(ow)-.8 G(sle).25 E 1.3 -.65(y, a)-.15 H
(nd J. K).65 E(urose, "Modelling TCP Throughput: A Simple Model and its)
-.15 E(Empirical V)122.398 384 Q(alidation", Proc A)-1.11 E
(CM SIGCOMM 1998.)-.4 E(Adamson, Bormann, et al.)36 696 Q
(Expires December 2003)105.89 E([P)119.09 E(age 52])-.15 E EP
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/F0 10/Times-Roman@0 SF(Internet Draft)36 48 Q(NORM Protocol)171.305 E
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-.5 E(esses)-.18 E F0(Brian Adamson)54 108 Q(adamson@itd.nrl.na)54 120 Q
(vy)-.2 E(.mil)-.65 E(Na)54 132 Q -.25(va)-.2 G 2.5(lR).25 G
(esearch Laboratory)-2.5 E -.8(Wa)54 144 S(shington, DC, USA, 20375).8 E
(Carsten Bormann)54 180 Q(cabo@tellique.de)54 192 Q -.7(Te)54 204 S
(llique K).7 E(ommunikationstechnik GmbH)-.35 E(Gusta)54 216 Q(v-Me)-.2
E(yer)-.15 E(-Allee 25 Geb ude 12)-.2 E(D-13355 Berlin, German)54 228 Q
(y)-.15 E(Mark Handle)54 264 Q(y)-.15 E(mjh@aciri.or)54 276 Q(g)-.18 E
(1947 Center Street, Suite 600)54 288 Q(Berk)54 300 Q(ele)-.1 E 1.3 -.65
(y, C)-.15 H 2.5(A9).65 G(4704)-2.5 E(Joe Mack)54 336 Q(er)-.1 E(mack)54
348 Q(er@itd.nrl.na)-.1 E(vy)-.2 E(.mil)-.65 E(Na)54 360 Q -.25(va)-.2 G
2.5(lR).25 G(esearch Laboratory)-2.5 E -.8(Wa)54 372 S
(shington, DC, USA, 20375).8 E(Adamson, Bormann, et al.)36 696 Q
(Expires December 2003)105.89 E([P)119.09 E(age 53])-.15 E EP
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