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/F0 10/Courier-Bold@0 SF(Internet Engineering Task Force)72 85 Q
(Sally Floyd)180 E 318(INTERNET-DRAFT ICIR)72 98 R 168
(draft-ietf-dccp-tfrc-voip-01.ps Eddie)72 111 R(Kohler)6 E
(Expires: August 2005)72 124 Q(UCLA)288 E(21 February 2005)408 137 Q/F1
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F2(Copyright Notice)72 462.6 Q F3(Cop)100.8 479.2 Q
(yright \(C\) The Internet Society \(2004\). All Rights Reserv)-.11 E
(ed.)-.165 E F2(Abstract)72 505.2 Q F3(TCP-Friendly Rate Control \(TFRC\
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-.275 E(operating in a best-ef)100.8 534.8 Q(fort Internet en)-.275 E
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100.8 110 Q -.15(ve)-.4 G(ntions).15 E F0 11(.......................)
10.44 G F2(4)11.5 E(2. V)100.8 122 Q(oIP V)-1.29 E(ariant Introduction)
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(oIP V)-1.29 E(ariant Congestion Control)-1.11 E F0 11
(.................)10.63 G F2(5)11.5 E(4. V)100.8 146 Q(oIP V)-1.29 E
(ariant Discussion)-1.11 E F0 11(....................)4.11 G F2(5)11.5 E
(4.1. The TCP Throughput Equation)115.8 158 Q F0 11(................)
9.48 G F2(6)11.5 E(4.2. Accounting for Header Size)115.8 170 Q F0 11
(.................)8.54 G F2(6)11.5 E(4.3. The V)115.8 182 Q
(oIP Min Interv)-1.29 E(al)-.25 E F0 11(...................)2.56 G F2(6)
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(.....................)8.66 G F2(13)6.5 E(Informati)100.8 350 Q .3 -.15
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(ariants of TFRC)-1.11 E F0 11(...............)2 G F2(14)6.5 E(Full Cop)
100.8 386 Q(yright Statement)-.1 E F0 11(....................)10.12 G F2
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(document are to be interpreted as described in [RFC 2119].)100.8 127.6
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([RFC 3448], without considering pack)100.8 264.8 Q(et size.)-.11 E
(This has consequences for the rate a TFRC)5.5 E<8d6f>100.8 277.8 Q 2.75
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(until such an ideal could be accomplished.)129.6 613.6 Q
(In addition, we note that the current TCP)5.5 E
(congestion control mechanisms are themselv)129.6 626.6 Q(es not v)-.165
E(ery ef)-.165 E(fecti)-.275 E .33 -.165(ve i)-.275 H 2.75(na).165 G
2.75(ne)-2.75 G -.44(nv)-2.75 G(ironment).44 E
(where there is a limitation along the re)129.6 639.6 Q -.165(ve)-.275 G
(rse path in pps.).165 E(While the TCP)5.5 E(mechanisms do pro)129.6
652.6 Q(vide an incenti)-.165 E .33 -.165(ve t)-.275 H 2.75(ou).165 G
(se lar)-2.75 E(ge data pack)-.198 E(ets, TCP does not include)-.11 E
(an)129.6 665.6 Q 2.75(ye)-.165 G -.275(ff)-2.75 G(ecti).275 E .33 -.165
(ve c)-.275 H(ongestion control mechanisms for the stream of small).165
E(ackno)129.6 678.6 Q(wledgement pack)-.275 E(ets on the re)-.11 E -.165
(ve)-.275 G(rse path.).165 E(Gi)5.5 E -.165(ve)-.275 G 2.75(nt).165 G
(he ar)-2.75 E(guments abo)-.198 E -.165(ve)-.165 G 2.75(,i).165 G 2.75
(ts)-2.75 G(eems)-2.75 E(acceptable to us to assume a netw)129.6 691.6 Q
(ork limitation in Bps rather than in pps in)-.11 E
(considering the minimum sending rate of telephon)129.6 704.6 Q 2.75(yt)
-.165 G(raf)-2.75 E(\214c.")-.275 E(Flo)72 769 Q(yd/K)-.11 E 284.171
(ohler Section)-.385 F 2.75(2. [P)2.75 F(age 4])-.165 E 0 Cg EP
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(August 2005)2.75 E(February 2005)103.569 E -.385(Tr)100.8 85 S(anslati\
ng the discussion in [RFC 3714] to the congestion control mechanisms of\
 TFRC,).385 E(it seems acceptable to standardize a v)100.8 98 Q
(ariant of TFRC that allo)-.275 E(ws V)-.275 E(oIP \215o)-1.419 E
(ws sending small)-.275 E(pack)100.8 111 Q(ets to achie)-.11 E .33 -.165
(ve a r)-.275 H(ough f).165 E(airness with TCP \215o)-.11 E
(ws in terms of the sending rate in Bps,)-.275 E
(rather than in terms of the sending rate in pps.)100.8 124 Q
(This is accomplished by a simple tw)5.5 E(o-line)-.11 E
(modi\214cation at the TFRC sender)100.8 137 Q 2.75(,a)-.44 G 2.75(sd)
-2.75 G(escribed belo)-2.75 E 4.18 -.715(w. N)-.275 H 2.75(oc).715 G
(hanges are required at the)-2.75 E(TFRC recei)100.8 150 Q -.165(ve)
-.275 G -.605(r.).165 G(Ho)100.8 166.6 Q(we)-.275 E -.165(ve)-.275 G .88
-.44(r, b).165 H(ecause the bottlenecks in the netw).44 E(ork in f)-.11
E(act can include limitations in pps as)-.11 E(well as in Bps, we pay s\
pecial attention to the potential dangers of encouraging a lar)100.8
179.6 Q(ge)-.198 E(deplo)100.8 192.6 Q(yment of best-ef)-.11 E
(fort traf)-.275 E
(\214c in the Internet consisting entirely of small pack)-.275 E 2.75
(ets. This)-.11 F(is)2.75 E
(discussed in more detail in Section 4.3. In addition, as ag)100.8 205.6
Q(ain discussed in Section 4.3, the)-.055 E -1.419(Vo)100.8 218.6 S
(IP v)1.419 E(ariant of TFRC includes the limitation of the Min Interv)
-.275 E(al between pack)-.275 E(ets of 10 ms.)-.11 E/F1 11/Times-Bold@0
SF(3.)72 244.6 Q/F2 14/Times-Bold@0 SF -1.4(Vo)5.5 G(IP V)1.4 E
(ariant Congestion Contr)-1.288 E(ol)-.252 E F0
(TFRC uses the TCP throughput equation gi)100.8 261.2 Q -.165(ve)-.275 G
2.75(ni).165 G 2.75(nS)-2.75 G(ection 3.1 of [RFC 3448], which gi)-2.75
E -.165(ve)-.275 G(s).165 E(the allo)100.8 274.2 Q
(wed sending rate X in bytes per second as a function of the loss e)
-.275 E -.165(ve)-.275 G(nt rate, pack).165 E(et)-.11 E
(size, and round-trip time.)100.8 287.2 Q
([RFC 3448] speci\214es that the pack)5.5 E(et size s used in the)-.11 E
(throughput equation should be the pack)100.8 300.2 Q
(et size used by the application, or the estimated)-.11 E(mean pack)
100.8 313.2 Q(et size if there are v)-.11 E(ariations in the pack)-.275
E(et size depending on the data.)-.11 E(This gi)5.5 E -.165(ve)-.275 G
(s).165 E(rough f)100.8 326.2 Q(airness with TCP \215o)-.11 E
(ws using the same pack)-.275 E(et size.)-.11 E(The V)100.8 342.8 Q
(oIP v)-1.419 E(ariant changes this beha)-.275 E(vior in the follo)-.22
E(wing w)-.275 E(ays.)-.11 E 12.65<8354>100.8 359.4 S(he nominal pack)
-12.65 E(et size s is set to 1460 bytes.)-.11 E -.165(Fo)5.5 G(llo).165
E(wing [RFC 3714], this pro)-.275 E(vides a)-.165 E(goal of f)117.3
372.4 Q(airness, in terms of the sending rate in bytes per second, with\
 a TCP \215o)-.11 E 2.75(ww)-.275 G(ith)-2.75 E
(1460 bytes of application data per pack)117.3 385.4 Q(et.)-.11 E 12.65
<8354>100.8 402 S(he allo)-12.65 E
(wed transmit rate X in bytes per second is reduced by a f)-.275 E
(actor that accounts for)-.11 E(pack)117.3 415 Q(et header size.)-.11 E
(This gi)5.5 E -.165(ve)-.275 G 2.75(st).165 G
(he application some incenti)-2.75 E -.165(ve)-.275 G 2.75(,b).165 G
-.165(ey)-2.75 G(ond the Min Interv).165 E(al,)-.275 E
(not to use unnecessarily small pack)117.3 428 Q 2.75(ets. In)-.11 F
(particular)2.75 E 2.75(,w)-.44 G 2.75(ei)-2.75 G(ntroduce a ne)-2.75 E
2.75(wp)-.275 G(arameter H,)-2.75 E(which represents the e)117.3 441 Q
(xpected size in bytes of netw)-.165 E
(ork and transport headers to be used)-.11 E(on the TFRC connection')
117.3 454 Q 2.75(sp)-.605 G(ack)-2.75 E 2.75(ets. This)-.11 F
(is used to reduce the allo)2.75 E(wed transmit rate X)-.275 E(as follo)
117.3 467 Q(ws:)-.275 E 2.75(X<)117.3 483.6 S 2.75(-X*s)-2.75 G
(_true / \(s_true + H\),)-2.75 E(where s_true is the true a)117.3 500.2
Q -.165(ve)-.22 G(rage data pack).165 E
(et size for the connection in bytes, e)-.11 E(xcluding)-.165 E
(the transport and netw)117.3 513.2 Q(ork headers.)-.11 E
(The H parameter is set to the constant 40 bytes.)117.3 529.8 Q
(Thus, if the V)5.5 E(oIP TFRC application)-1.419 E
(used 40-byte data se)117.3 542.8 Q(gments, the allo)-.165 E
(wed transmit rate X w)-.275 E(ould be halv)-.11 E(ed to account for)
-.165 E(the f)117.3 555.8 Q(act that half of the sending rate w)-.11 E
(ould be used by the headers.)-.11 E(Section 4.2 justi\214es)5.5 E
(this de\214nition.)117.3 568.8 Q(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G
.88 -.44(r, a c).165 H(onnection using the V).44 E(oIP v)-1.419 E
(ariant MA)-.275 E 2.75(Yi)-1.155 G(nstead use a more)-2.75 E
(precise estimate of H, based on the actual netw)117.3 581.8 Q
(ork and transport headers to be used on)-.11 E(the connection')117.3
594.8 Q 2.75(sp)-.605 G(ack)-2.75 E 2.75(ets. F)-.11 F(or e)-.165 E
(xample, a DCCP connection [DCCP] o)-.165 E -.165(ve)-.165 G 2.75(rI)
.165 G(Pv4, where)-2.75 E(data pack)117.3 607.8 Q
(ets use the DCCP-Data pack)-.11 E
(et type, and there are no IP or DCCP options,)-.11 E
(could set H to 20 + 12 = 32 bytes.)117.3 620.8 Q 12.65<8346>100.8 637.4
S(inally)-12.65 E 2.75(,t)-.715 G(he V)-2.75 E(oIP v)-1.419 E
(ariant of TFRC enforces a Min Interv)-.275 E(al between pack)-.275 E
(ets of 10 ms.)-.11 E 2.75<418d>117.3 650.4 S .55 -.275(ow t)-2.75 H
(hat wished to e).275 E(xceed this Min Interv)-.165 E
(al MUST use the con)-.275 E -.165(ve)-.44 G(ntional TFRC).165 E
(equations, rather than the V)117.3 663.4 Q(oIP v)-1.419 E 2.75
(ariant. The)-.275 F(moti)2.75 E -.275(va)-.275 G
(tion for this is discussed belo).275 E -.715(w.)-.275 G F1(4.)72 689.4
Q F2 -1.4(Vo)5.5 G(IP V)1.4 E(ariant Discussion)-1.288 E F0(Flo)72 769 Q
(yd/K)-.11 E 284.171(ohler Section)-.385 F 2.75(4. [P)2.75 F(age 5])
-.165 E 0 Cg EP
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(August 2005)2.75 E(February 2005)103.569 E/F1 11/Times-Bold@0 SF(4.1.)
72 85 Q/F2 13/Times-Bold@0 SF(The TCP Thr)5.5 E(oughput Equation)-.234 E
F0(The V)100.8 101.6 Q(oIP v)-1.419 E
(ariant of TFRC uses the TCP throughput equation gi)-.275 E -.165(ve)
-.275 G 2.75(ni).165 G 2.75(n[)-2.75 G(RFC 3448].)-2.75 E(As)5.5 E(sho)
100.8 114.6 Q(wn in T)-.275 E(able 1 of [RFC 3714], for high pack)-.88 E
(et drop rates, this throughput equation gi)-.11 E -.165(ve)-.275 G(s)
.165 E(rough f)100.8 127.6 Q(airness with most aggressi)-.11 E .33 -.165
(ve p)-.275 H(ossible current TCP: a SA).165 E(CK TCP \215o)-.44 E 2.75
(wu)-.275 G(sing)-2.75 E(timestamps and ECN.)100.8 140.6 Q F1(4.2.)72
166.6 Q F2(Accounting f)5.5 E(or Header Size)-.325 E F0([RFC 3714] mak)
100.8 183.2 Q
(es the optimistic assumption that the limitation of the netw)-.11 E
(ork is in)-.11 E
(bandwidth in bytes per second \(Bps\), and not in CPU c)100.8 196.2 Q
(ycles or in pack)-.165 E(ets per second \(pps\).)-.11 E(Ho)100.8 209.2
Q(we)-.275 E -.165(ve)-.275 G .88 -.44(r, s).165 H(ome attention must b\
e paid to the load in pps as well as to the load in Bps.).44 E(Ev)100.8
222.2 Q(en aside from the Min Interv)-.165 E(al, the V)-.275 E(oIP v)
-1.419 E(ariant of TFRC gi)-.275 E -.165(ve)-.275 G 2.75(st).165 G
(he application some)-2.75 E(incenti)100.8 235.2 Q .33 -.165(ve t)-.275
H 2.75(ou).165 G(se fe)-2.75 E(wer b)-.275 E(ut lar)-.22 E(ger pack)
-.198 E(ets, when lar)-.11 E(ger pack)-.198 E(ets w)-.11 E(ould suf)-.11
E(\214ce, by including)-.275 E(the bandwidth used by the pack)100.8
248.2 Q(et header in the allo)-.11 E(wed sending rate.)-.275 E(As an e)
100.8 264.8 Q(xample, a sender using 120-byte pack)-.165 E
(ets needs a TCP-friendly rate of 128 Kbps to)-.11 E
(send 96 Kbps of application data.)100.8 277.8 Q
(This is because the TCP-friendly rate is reduced by a)5.5 E -.11(fa)
100.8 290.8 S
(ctor of s_true/\(s_true + H\) = 120/160, to account for the ef).11 E
(fect of pack)-.275 E(et headers.)-.11 E(If the)5.5 E
(sender suddenly switched to 40-byte data se)100.8 303.8 Q
(gments, the allo)-.165 E(wed sending rate w)-.275 E(ould reduce)-.11 E
(to 64 Kbps of application data; and one-byte data se)100.8 316.8 Q
(gments w)-.165 E(ould reduce the allo)-.11 E(wed)-.275 E
(sending rate to 3.12 Kbps of application data.)100.8 329.8 Q(\(In f)5.5
E(act, the Min Interv)-.11 E(al w)-.275 E(ould pre)-.11 E -.165(ve)-.275
G(nt).165 E(senders from achie)100.8 342.8 Q
(ving these rates, since applications using the V)-.275 E(oIP v)-1.419 E
(ariant cannot send)-.275 E(more than 100 pack)100.8 355.8 Q
(ets per second.\))-.11 E(The V)100.8 372.4 Q(oIP v)-1.419 E(ariant ass\
umes 40 bytes for the header size, although the header could be lar)
-.275 E(ger)-.198 E(\(due to IP options, IPv6, IP tunnels, and the lik)
100.8 385.4 Q(e\) or smaller \(due to header compression\))-.11 E
(on the wire, because using the e)100.8 398.4 Q
(xact header size in bytes w)-.165 E(ould ha)-.11 E .33 -.165(ve l)-.22
H(ittle additional).165 E 2.75(bene\214t. The)100.8 411.4 R -1.419(Vo)
2.75 G(IP v)1.419 E(ariant')-.275 E 2.75(su)-.605 G
(se of an assumed 40-byte header is suf)-2.75 E
(\214cient to get a rough)-.275 E(estimate of the throughput, and to gi)
100.8 424.4 Q .33 -.165(ve t)-.275 H(he application some incenti).165 E
.33 -.165(ve n)-.275 H(ot to use).165 E(unnecessarily-man)100.8 437.4 Q
2.75(ys)-.165 G(mall pack)-2.75 E 2.75(ets. Because)-.11 F
(we are only aiming at rough f)2.75 E(airness, and at a)-.11 E
(rough incenti)100.8 450.4 Q .33 -.165(ve f)-.275 H(or applications, th\
e use of a 40-byte header in the calculations of the).165 E
(header bandwidth seems suf)100.8 463.4 Q(\214cient.)-.275 E F1(4.3.)72
489.4 Q F2(The V)5.5 E(oIP Min Inter)-1.3 E -.13(va)-.13 G(l).13 E F0
(The header size calculation pro)100.8 506 Q(vides an incenti)-.165 E
.33 -.165(ve f)-.275 H(or applications to use fe).165 E(wer)-.275 E 2.75
(,b)-.44 G(ut lar)-2.97 E(ger)-.198 E(,)-.44 E(pack)100.8 519 Q 2.75
(ets. Another)-.11 F(incenti)2.75 E .33 -.165(ve i)-.275 H 2.75(st).165
G(hat when the path limitation is in pps, the application using)-2.75 E
(more small pack)100.8 532 Q(ets is lik)-.11 E(ely to recei)-.11 E .33
-.165(ve m)-.275 H(ore pack).165 E(et drops, and to ha)-.11 E .33 -.165
(ve t)-.22 H 2.75(or).165 G(educe its sending)-2.75 E(rate accordingly)
100.8 545 Q 5.5(.T)-.715 G
(hat is, if the congestion is in terms of pps, then the \215o)-5.5 E
2.75(ws)-.275 G(ending more)-2.75 E(pps will recei)100.8 558 Q .33 -.165
(ve m)-.275 H(ore congestion indications, and ha).165 E .33 -.165(ve t)
-.22 H 2.75(oa).165 G(djust its sending rate)-2.75 E(accordingly)100.8
571 Q 5.5(.H)-.715 G -.275(ow)-5.5 G -2.365 -.275(ev e).275 H .88 -.44
(r, t).275 H(he increased congestion caused by the use of small pack).44
E(ets in an)-.11 E(en)100.8 584 Q(vironment limited by pps is e)-.44 E
(xperienced not only by the \215o)-.165 E 2.75(wu)-.275 G
(sing the small pack)-2.75 E(ets, b)-.11 E(ut)-.22 E
(by all of the competing traf)100.8 597 Q(\214c on that congested link.)
-.275 E(These incenti)5.5 E -.165(ve)-.275 G 2.75(sa).165 G
(re therefore)-2.75 E(insuf)100.8 610 Q(\214cient to pro)-.275 E
(vide suf)-.165 E(\214cient protection for pps netw)-.275 E
(ork limitations.)-.11 E(The V)100.8 626.6 Q(oIP v)-1.419 E
(ariant for TFRC, then, includes a Min Interv)-.275 E(al of 10 ms.)-.275
E(This pro)5.5 E(vides)-.165 E
(additional restrictions on the use of unnecessarily man)100.8 639.6 Q
2.75(ys)-.165 G(mall pack)-2.75 E(ets.)-.11 E
(One justi\214cation for the Min Interv)100.8 656.2 Q
(al is the practical one that the applications that currently)-.275 E
-.11(wa)100.8 669.2 S(nt to send small pack).11 E(ets are the V)-.11 E
(oIP applications that send at most one pack)-1.419 E(et e)-.11 E -.165
(ve)-.275 G(ry 10).165 E(ms, so this restriction does not af)100.8 682.2
Q(fect current traf)-.275 E 2.75(\214c. A)-.275 F
(second justi\214cation is that there is)2.75 E
(no pressing need for best-ef)100.8 695.2 Q(fort traf)-.275 E
(\214c in the current Internet to send small pack)-.275 E(ets more)-.11
E(frequently than once e)100.8 708.2 Q -.165(ve)-.275 G
(ry 10 ms \(rather than taking the 10 ms delay at the sender).165 E 2.75
(,a)-.44 G(nd)-2.75 E(mer)100.8 721.2 Q(ging the tw)-.198 E 2.75(os)-.11
G(mall pack)-2.75 E(ets into one lar)-.11 E(ger one\).)-.198 E
(This 10 ms delay for mer)5.5 E(ging small)-.198 E(Flo)72 769 Q(yd/K)
-.11 E 275.921(ohler Section)-.385 F 2.75(4.3. [P)2.75 F(age 6])-.165 E
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 72.802(-DRAFT Expires:)-1.012 F
(August 2005)2.75 E(February 2005)103.569 E(pack)100.8 85 Q(ets is lik)
-.11 E(ely to be dominated by the netw)-.11 E(ork propag)-.11 E
(ation, transmission, and queueing)-.055 E(delays of best-ef)100.8 98 Q
(fort traf)-.275 E(\214c in the current Internet.)-.275 E
(As a result, our judgement w)5.5 E(ould be that)-.11 E
(the bene\214t to the user of ha)100.8 111 Q
(ving less than 10 ms between pack)-.22 E(ets is outweighed by the)-.11
E(bene\214t to the netw)100.8 124 Q(ork of a)-.11 E -.22(vo)-.22 G
(iding unnecessarily man).22 E 2.75(ys)-.165 G(mall pack)-2.75 E(ets.)
-.11 E(The Min Interv)100.8 140.6 Q(al causes the V)-.275 E(oIP v)-1.419
E(ariant of TFRC not to support applications sending)-.275 E(small pack)
100.8 153.6 Q(ets v)-.11 E(ery frequently)-.165 E 5.5(.C)-.715 G
(onsider a TFRC \215o)-5.5 E 2.75(ww)-.275 G(ith a \214x)-2.75 E
(ed pack)-.165 E(et size of 100 bytes,)-.11 E -.22(bu)100.8 166.6 S 2.75
(tw).22 G(ith a v)-2.75 E(ariable sending rate and a f)-.275 E
(airly uncongested path.)-.11 E(When this \215o)5.5 E 2.75(ww)-.275 G
(as sending)-2.86 E(at most 100 pps, it w)100.8 179.6 Q
(ould be able to use the V)-.11 E(oIP v)-1.419 E(ariant of TFRC.)-.275 E
(If the \215o)5.5 E 2.75(ww)-.275 G(ished to)-2.75 E
(increase its sending rate to more than 100 pps, b)100.8 192.6 Q
(ut to k)-.22 E(eep the same pack)-.11 E(et size, it w)-.11 E(ould)-.11
E(no longer be able to achie)100.8 205.6 Q .33 -.165(ve t)-.275 H
(his with the V).165 E(oIP v)-1.419 E(ariant to TFRC, and w)-.275 E
(ould ha)-.11 E .33 -.165(ve t)-.22 H 2.75(os).165 G(wich)-2.75 E
(to the def)100.8 218.6 Q(ault TFRC, recei)-.11 E
(ving a dramatic, discontinuous decrease in its allo)-.275 E
(wed sending)-.275 E 2.75(rate. This)100.8 231.6 R
(seems not only acceptable, b)2.75 E
(ut desirable for the global Internet.)-.22 E(What is to pre)100.8 248.2
Q -.165(ve)-.275 G(nt \215o).165 E
(ws from opening multiple connections, each with a 10 ms Min)-.275 E
(Interv)100.8 261.2 Q
(al, and thereby getting around the limitation of the Min Interv)-.275 E
2.75(al? Ob)-.275 F(viously)-.165 E 2.75(,t)-.715 G(here is)-2.75 E
(nothing to pre)100.8 274.2 Q -.165(ve)-.275 G(nt \215o).165 E
(ws from doing this, just as there is currently nothing to pre)-.275 E
-.165(ve)-.275 G(nt \215o).165 E(ws)-.275 E(from using UDP)100.8 287.2 Q
2.75(,o)-1.221 G 2.75(rf)-2.75 G
(rom opening multiple parallel TCP connections, or from using their)
-2.75 E -.275(ow)100.8 300.2 S 2.75(nc).275 G
(ongestion control mechanism.)-2.75 E
(Of course, implementations or middlebox)5.5 E(es are also)-.165 E(free\
 to limit the number of parallel TFRC connections opened to the same de\
stination in)100.8 313.2 Q
(times of congestion, if that seems desirable.)100.8 326.2 Q(And \215o)
5.5 E(ws that open multiple parallel)-.275 E
(connections are subject to the incon)100.8 339.2 Q -.165(ve)-.44 G
(niences of reordering and the lik).165 E 2.75(e. But)-.11 F -2.365
-.275(ev e)2.75 H 2.75(nw).275 G(ithout)-2.75 E 2.75(am)100.8 352.2 S
(echanism to pre)-2.75 E -.165(ve)-.275 G(nt \215o).165 E(ws from sub)
-.275 E -.165(ve)-.165 G(rting the Min Interv).165 E
(al by opening multiple)-.275 E
(parallel connections, it seems useful to include the Min Interv)100.8
365.2 Q(al in the V)-.275 E(oIP v)-1.419 E(ariant of)-.275 E(TFRC.)100.8
378.2 Q/F1 11/Times-Bold@0 SF(5.)72 404.2 Q/F2 14/Times-Bold@0 SF -.35
(Fa)5.5 G(ster Restart Intr).35 E(oduction)-.252 E F0(In an)100.8 420.8
Q 2.75(yR)-.165 G(TT)-3.41 E 2.75(,aT)-.814 G(FRC \215o)-2.75 E 2.75(wm)
-.275 G(ay not send more than twice X_recv)-2.75 E 2.75(,t)-.715 G
(he amount that w)-2.75 E(as)-.11 E(recei)100.8 433.8 Q -.165(ve)-.275 G
2.75(di).165 G 2.75(nt)-2.75 G(he pre)-2.75 E(vious R)-.275 E(TT)-.66 E
5.5(.T)-.814 G(he TFRC nofeedback timer reduces this number by half)-5.5
E(during each nofeedback timer interv)100.8 446.8 Q
(al \(at least four R)-.275 E(TT\) in which no feedback is recei)-.66 E
-.165(ve)-.275 G(d.).165 E(The ef)100.8 459.8 Q
(fect of this is that applications must slo)-.275 E 2.75(ws)-.275 G
(tart after going idle for an)-2.75 E 2.75(ys)-.165 G(igni\214cant)-2.75
E(length of time, in the absence of mechanisms such as Quick-Start [JF)
100.8 472.8 Q(AS05].)-.814 E(This beha)100.8 489.4 Q
(vior is safe for best-ef)-.22 E(fort traf)-.275 E(\214c in the netw)
-.275 E 2.75(ork. A)-.11 F(silent application stops)2.75 E(recei)100.8
502.4 Q(ving feedback about current netw)-.275 E
(ork conditions, and thus should not be able to send at)-.11 E
(an arbitrary rate.)100.8 515.4 Q(But this beha)5.5 E
(vior can damage the percei)-.22 E -.165(ve)-.275 G 2.75(dp).165 G
(erformance of interacti)-2.75 E -.165(ve)-.275 G
(applications such as v)100.8 528.4 Q 2.75(oice. Connections)-.22 F
(for interacti)2.75 E .33 -.165(ve t)-.275 H(elephon).165 E 2.75(ya)
-.165 G(nd conference)-2.75 E(applications, for e)100.8 541.4 Q
(xample, will usually ha)-.165 E .33 -.165(ve o)-.22 H(ne party acti)
.165 E .33 -.165(ve a)-.275 H 2.75(tat).165 G(ime, with seamless)-2.75 E
(switching between acti)100.8 554.4 Q .33 -.165(ve p)-.275 H 2.75
(arties. Incurring).165 F(slo)2.75 E 2.75(ws)-.275 G(tart on e)-2.75 E
-.165(ve)-.275 G(ry switch between parties may).165 E(cause percei)100.8
567.4 Q -.165(ve)-.275 G 2.75(dp).165 G(erformance to seriously de)-2.75
E 2.75(grade. Some)-.165 F(of the strate)2.75 E(gies suggested for)-.165
E(coping with this problem, such as sending padding data during applica\
tion idle periods,)100.8 580.4 Q(might ha)100.8 593.4 Q .33 -.165(ve w)
-.22 H(orse ef).055 E(fects on the netw)-.275 E
(ork than simply switching onto the desired rate with)-.11 E(no slo)
100.8 606.4 Q 2.75(ws)-.275 G(tart.)-2.75 E
(There is some justi\214cation for some)100.8 623 Q
(what accelerating the slo)-.275 E 2.75(ws)-.275 G
(tart process after idle)-2.75 E(periods \(as opposed to at the be)100.8
636 Q(ginning of a connection\).)-.165 E 2.75(Ac)5.5 G(onnection that f)
-2.75 E(airly achie)-.11 E -.165(ve)-.275 G(s).165 E 2.75(as)100.8 649 S
(ending rate of X has pro)-2.75 E -.165(ve)-.165 G
(d, at least, that some path between the endpoints can support).165 E
(that rate.)100.8 662 Q(The path might change, due to endpoint reset or\
 routing adjustments; or man)5.5 E(y)-.165 E(ne)100.8 675 Q 2.75(wc)
-.275 G
(onnections might start up, signi\214cantly reducing the application')
-2.75 E 2.75(sf)-.605 G(air rate.)-2.86 E(Ho)5.5 E(we)-.275 E -.165(ve)
-.275 G -.44(r,).165 G(it seems reasonable to allo)100.8 688 Q 2.75(wa)
-.275 G 2.75(na)-2.75 G(pplication to contrib)-2.75 E
(ute to transient congestion in times of)-.22 E
(change, in return for impro)100.8 701 Q(ving application responsi)-.165
E -.165(ve)-.275 G(ness after idle periods.).165 E(Flo)72 769 Q(yd/K)
-.11 E 284.171(ohler Section)-.385 F 2.75(5. [P)2.75 F(age 7])-.165 E 0
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 72.802(-DRAFT Expires:)-1.012 F
(August 2005)2.75 E(February 2005)103.569 E
(This document suggests a relati)100.8 85 Q -.165(ve)-.275 G
(ly simple approach to this problem.).165 E(Some protocols)5.5 E
(using TFRC [CCID 3 PR)100.8 98 Q(OFILE] already specify that the allo)
-.44 E(wed sending rate is ne)-.275 E -.165(ve)-.275 G(r).165 E
(reduced belo)100.8 111 Q 2.75(wt)-.275 G
(he RFC-3390 sending rate of four pack)-2.75 E(ets per R)-.11 E
(TT during an idle period.)-.66 E -.165(Fa)100.8 124 S
(ster Restart speci\214es that the allo).165 E(wed sending rate is ne)
-.275 E -.165(ve)-.275 G 2.75(rr).165 G(educed belo)-2.75 E 2.75(we)
-.275 G(ight pack)-2.75 E(ets)-.11 E(per R)100.8 137 Q(TT)-.66 E 2.75
(,f)-.814 G(or small pack)-2.75 E 2.75(ets. In)-.11 F
(addition, because \215o)2.75 E(ws already ha)-.275 E .33 -.165(ve s)
-.22 H(ome \(possibly old\)).165 E(information about the path, F)100.8
150 Q(aster Restart allo)-.165 E(ws \215o)-.275 E
(ws to quadruple their sending rate in)-.275 E -2.365 -.275(ev e)100.8
163 T(ry congestion-free R).275 E(TT)-.66 E 2.75(,i)-.814 G
(nstead of doubling, up to the pre)-2.75 E(viously achie)-.275 E -.165
(ve)-.275 G 2.75(dr).165 G 2.75(ate. An)-2.75 F(y)-.165 E(congestion e)
100.8 176 Q -.165(ve)-.275 G(nt stops this f).165 E
(aster restart and switches TFRC into congestion a)-.11 E -.22(vo)-.22 G
(idance.).22 E/F1 11/Times-Bold@0 SF(6.)72 202 Q/F2 14/Times-Bold@0 SF
-.35(Fa)5.5 G(ster Restart Congestion Contr).35 E(ol)-.252 E F0
(DRAFT DRAFT DRAFT)100.8 218.6 Q 2.75(Ac)100.8 235.2 S(onnection goes "\
idle" when the application has nothing to send for at least a nofeedbac\
k)-2.75 E(interv)100.8 248.2 Q(al \(as least four round-trip times\).)
-.275 E(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44(r, w).165 H(hen F)
.44 E(aster Restart is used, the)-.165 E
(transport layer MUST send a "ping" pack)100.8 261.2 Q(et e)-.11 E -.165
(ve)-.275 G(ry se).165 E -.165(ve)-.275 G
(ral round trip times, to continue).165 E(getting R)100.8 274.2 Q
(TT samples and some idea of the loss e)-.66 E -.165(ve)-.275 G
(nt rate.).165 E -.165(Fa)100.8 290.8 S(ster Restart introduces four ne)
.165 E 2.75(ws)-.275 G(tate v)-2.75 E(ariables to TFRC, as follo)-.275 E
(ws.)-.275 E(T_idle)100.8 307.4 Q(The time the connection went idle.)
129.6 320.4 Q(X_f)100.8 337 Q(ast_max)-.11 E
(The rate at which to turn of)129.6 350 Q 2.75(ff)-.275 G
(aster restart; 0 if not in f)-2.86 E(aster restart.)-.11 E
(Initially 0.)5.5 E(X_acti)100.8 366.6 Q -.165(ve)-.275 G(_recv).165 E
(The rate at which pack)129.6 379.6 Q(ets were recei)-.11 E -.165(ve)
-.275 G 2.75(di).165 G 2.75(nt)-2.75 G(he last acti)-2.75 E .33 -.165
(ve s)-.275 H(ending period.).165 E(An acti)5.5 E -.165(ve)-.275 G
(sending period is a period in which the sender w)129.6 392.6 Q
(as neither idle nor in f)-.11 E(ast restart.)-.11 E(It)5.5 E
(is initialized to 0 until there has been an acti)129.6 405.6 Q .33
-.165(ve s)-.275 H(ending period.).165 E(T_acti)100.8 422.2 Q -.165(ve)
-.275 G(_recv).165 E(The most recent time in an acti)129.6 435.2 Q .33
-.165(ve s)-.275 H(ending period.).165 E(Se)100.8 451.8 Q -.165(ve)-.275
G(ral pre).165 E(viously e)-.275 E(xisting state v)-.165 E
(ariables are also particularly important, as follo)-.275 E(ws.)-.275 E
21.463(RT)100.8 468.4 S(he R)-21.463 E(TT estimate; k)-.66 E
(ept current during an)-.11 E 2.75(yi)-.165 G
(dle periods as described abo)-2.75 E -.165(ve)-.165 G(.).165 E 20.858
(XT)100.8 485 S(he current allo)-20.858 E
(wed sending rate in bytes per second.)-.275 E 23.3(pT)100.8 501.6 S
(he recent loss e)-23.3 E -.165(ve)-.275 G(nt rate.).165 E(X_recv)100.8
518.2 Q(The rate at which the recei)129.6 531.2 Q -.165(ve)-.275 G 2.75
(re).165 G(stimates that data w)-2.75 E(as recei)-.11 E -.165(ve)-.275 G
2.75(ds).165 G(ince the last)-2.75 E(feedback report w)129.6 544.2 Q
(as sent.)-.11 E(Note that this includes "ping" pack)5.5 E
(ets sent during idle)-.11 E(periods \(abo)129.6 557.2 Q -.165(ve)-.165
G 2.75(\)a).165 G 2.75(sw)-2.75 G(ell as application pack)-2.75 E(ets.)
-.11 E(Other v)100.8 573.8 Q(ariables ha)-.275 E .33 -.165(ve v)-.22 H
(alues as described in [RFC 3448].)-.11 E F1(6.1.)72 599.8 Q/F3 13
/Times-Bold@0 SF(Entering and Lea)5.5 E(ving Idle P)-.325 E(eriods)-.26
E F0(When the application has nothing to send \(an idle period is enter\
ed\), TFRC sets T_idle :=)100.8 616.4 Q(no)100.8 629.4 Q -.715(w.)-.275
G(When the application has something to send, TFRC uses the follo)100.8
646 Q(wing code to determine)-.275 E(whether it is lea)100.8 659 Q
(ving an idle period, and if so, ho)-.22 E 2.75(wt)-.275 G
(he sending rate should be adjusted.)-2.75 E(The)5.5 E(code will use F)
100.8 672 Q(aster Restart up to the full last f)-.165 E
(air rate after an idle period of 10 minutes or)-.11 E
(less; will not use F)100.8 685 Q(ast T)-.165 E
(estart after an idle period of 30 minutes or more; and interpolates)
-.77 E(between these e)100.8 698 Q
(xtremes after idle periods between 10 and 30 minutes.)-.165 E(Flo)72
769 Q(yd/K)-.11 E 275.921(ohler Section)-.385 F 2.75(6.1. [P)2.75 F
(age 8])-.165 E 0 Cg EP
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(August 2005)2.75 E(February 2005)103.569 E/F1 11/Courier@0 SF
(If \(now - T_idle\) > max\(R, 1 / max\(X_calc, s/t_mbi\)\),)100.8 85 Q
(/* If idle for <= 10 minutes, end fast start at the)120.6 98 Q
(full last fair rate; if idle for >= 30 minutes,)140.4 111 Q
(don't do fast start; in between, interpolate. */)140.4 124 Q
(delta_T := now - T_active_recv)120.6 137 Q 6.6(F:)120.6 150 S 6.6(=\()
-6.6 G(30 min - min\(max\(delta_T, 10 min\), 30 min\)\) / 20 min)-6.6 E
(/* Initialize X_fast_max to a fraction of the last active)120.6 163 Q
(rate */)140.4 176 Q(X_fast_max := F*X_active_recv)120.6 189 Q
(/* Alter the cached X_recv so we start out between 4)120.6 202 Q
(and 8 packets/RTT */)140.4 215 Q(X_recv := max\(2*s/R, X_recv\))120.6
228 Q/F2 11/Times-Bold@0 SF(6.2.)72 260 Q/F3 13/Times-Bold@0 SF -.325
(Fe)5.5 G(edback P).325 E(ack)-.13 E(ets)-.13 E F0(The core of the F)
100.8 276.6 Q(aster Restart algorithm is a replacement for the 4th step\
 of Section 4.3,)-.165 E(Sender beha)100.8 289.6 Q
(vior when a feedback pack)-.22 E(et is recei)-.11 E -.165(ve)-.275 G
(d, of [RFC 3448], as follo).165 E(ws.)-.275 E F1
(To update X when you receive a feedback packet)100.8 308.6 Q
(----------------------------------------------)100.8 321.6 Q
(If \(2*X_recv < X_fast_max\) and the feedback packet)100.8 334.6 Q
(indicates a loss or mark,)140.4 347.6 Q
(/* Stop faster restart at the first sign of congestion */)120.6 360.6 Q
(X_fast_max := 0,)120.6 373.6 Q(X_recv := X_recv/2.)120.6 386.6 Q
(If p > 0,)100.8 399.6 Q
(Calculate X_calc using the TCP throughput equation.)120.6 412.6 Q
(If \(2*X_recv < X_fast_max\),)120.6 425.6 Q(/* Faster restart case */)
140.4 438.6 Q 6.6(X:)140.4 451.6 S 6.6(=m)-6.6 G
(ax\(min\(X_calc, 4*X_recv\), s/t_mbi\).)-6.6 E(Else)120.6 464.6 Q
(X_fast_max := 0,)140.4 477.6 Q(/* Stop faster restart */)13.2 E 6.6(X:)
140.4 490.6 S 6.6(=m)-6.6 G(ax\(min\(X_calc, 2*X_recv\), s/t_mbi\).)-6.6
E(Else)100.8 503.6 Q(If \(t_now - tld >= R\))120.6 516.6 Q 6.6(X:)140.4
529.6 S 6.6(=m)-6.6 G(ax\(min\(2*X, 2*X_recv\), s/R\);)-6.6 E
(tld := now.)140.4 542.6 Q F2(7.)72 574.6 Q/F4 14/Times-Bold@0 SF -.35
(Fa)5.5 G(ster Restart Discussion).35 E F0
(TCP has historically dealt with idleness either by k)100.8 591.2 Q
(eeping cwnd entirely open \("immediate)-.11 E
(start"\) or by entering slo)100.8 604.2 Q 2.75(ws)-.275 G
(tart, as recommended in RFC 2581.)-2.75 E(The \214rst option is too)5.5
E(liberal, the second too conserv)100.8 617.2 Q(ati)-.275 E -.165(ve)
-.275 G 5.5(.C).165 G(learly a short idle period is not a ne)-5.5 E 2.75
(wc)-.275 G(onnection:)-2.75 E(recent e)100.8 630.2 Q(vidence sho)-.275
E(ws that the connection could f)-.275 E(airly sustain some rate.)-.11 E
(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44(r, l).165 H(onger).44 E
(idle periods are more problematic, and idle periods of hours w)100.8
643.2 Q(ould seem to require slo)-.11 E(w)-.275 E 2.75(start. RFC)100.8
656.2 R(2861 [RFC 2861], which is f)2.75 E
(airly widely implemented [MAF04], gi)-.11 E -.165(ve)-.275 G 2.75(sa)
.165 G(moderate mechanism for TCP)100.8 669.2 Q 2.75(,w)-1.221 G
(here the congestion windo)-2.75 E 2.75(wi)-.275 G 2.75(sh)-2.75 G(alv)
-2.75 E(ed for e)-.165 E -.165(ve)-.275 G(ry round-trip).165 E
(time that the sender has remained idle, and the windo)100.8 682.2 Q
2.75(wi)-.275 G 2.75(nr)-2.75 G(e-opened in slo)-2.75 E
(w-start when the)-.275 E(idle period is o)100.8 695.2 Q -.165(ve)-.165
G -.605(r.).165 G -.165(Fa)100.8 711.8 S
(ster Restart should be acceptable for TFRC if its w).165 E
(orst-case scenario is acceptable.)-.11 E(Realistic w)100.8 724.8 Q
(orst-case scenarios might include the follo)-.11 E(wing scenarios:)
-.275 E(Flo)72 769 Q(yd/K)-.11 E 284.171(ohler Section)-.385 F 2.75
(7. [P)2.75 F(age 9])-.165 E 0 Cg EP
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(August 2005)2.75 E(February 2005)103.569 E 12.65<8354>100.8 85 S
(he path changes and the old rate isn')-12.65 E 2.75(ta)-.198 G
(cceptable on the ne)-2.75 E 2.75(wp)-.275 G 2.75(ath. R)-2.75 F
(TTs are shorter)-.66 E(on the ne)117.3 98 Q 2.75(wp)-.275 G
(ath too, so F)-2.75 E
(aster Restart clobbers other connections for multiple R)-.165 E(TTs,)
-.66 E(not just one.)117.3 111 Q 12.65<8354>100.8 127.6 S .22 -.11
(wo \()-13.53 H(or more\) connections enter F).11 E
(aster Restart simultaneously)-.165 E 5.5(.T)-.715 G(he pack)-5.5 E
(et drop rate)-.11 E(can be twice as bad, for one R)117.3 140.6 Q(TT)
-.66 E 2.75(,t)-.814 G(han if the)-2.75 E 2.75(yh)-.165 G(ad slo)-2.75 E
(w-started after their idle periods.)-.275 E 12.65<8349>100.8 157.2 S
2.75(na)-12.65 G(ddition to connections F)-2.75 E
(ast-Restarting, there are short TCP or DCCP connections)-.165 E
(starting and stopping all the time, with initial windo)117.3 170.2 Q
(ws of three or four pack)-.275 E 2.75(ets. There)-.11 F
(are also TCP connections with short quiescent periods \(web bro)117.3
183.2 Q(wsing sessions using)-.275 E(HTTP 1.1\).)117.3 196.2 Q
(The audio and video connections ha)5.5 E .33 -.165(ve i)-.22 H
(dle periods.).165 E(And the a)5.5 E -.275(va)-.22 G(ilable).275 E
(bandwidth might v)117.3 209.2 Q(ary o)-.275 E -.165(ve)-.165 G 2.75(rt)
.165 G(ime, because of bandwidth used by higher)-2.75 E(-priority traf)
-.22 E<8c63>-.275 E(\(routing traf)117.3 222.2 Q(\214c, and dif)-.275 E
2.75(fserv\). All)-.275 F(of this is happening at once, so the aggre)
2.75 E -.055(ga)-.165 G(te arri).055 E -.275(va)-.275 G(l).275 E
(rate naturally v)117.3 235.2 Q(aries from one R)-.275 E(TT to the ne)
-.66 E 2.75(xt. And)-.165 F(the congested link is an access)2.75 E
(link, not a backbone link, so the le)117.3 248.2 Q -.165(ve)-.275 G
2.75(lo).165 G 2.75(fs)-2.75 G(tatistical multiple)-2.75 E
(xing is not high enough to)-.165 E(mak)117.3 261.2 Q 2.75(ee)-.11 G
-.165(ve)-3.025 G(rything just look lik).165 E 2.75(el)-.11 G -.165(ove)
-2.75 G(ly white noise.).165 E
(Further analysis is required to analyze the ef)100.8 277.8 Q
(fects of these scenarios.)-.275 E 1.76 -.88(We n)100.8 294.4 T
(ote that F).88 E(aster Restart in V)-.165 E
(oIP TFRC is considerably more restrained that F)-1.419 E(aster)-.165 E
(Restart in the def)100.8 307.4 Q(ault TFRC;)-.11 E(in V)5.5 E
(oIP TFRC, the sender is restricted to sending at most one)-1.419 E
(pack)100.8 320.4 Q(et e)-.11 E -.165(ve)-.275 G(ry Min Interv).165 E
2.75(al. Similarly)-.275 F 2.75(,F)-.715 G(aster Restart in the def)
-2.915 E(ault TFRC is more restrained)-.11 E(that F)100.8 333.4 Q
(aster Restart w)-.165 E(ould be if added to TCP;)-.11 E
(TFRC is controlled of a sending rate, while)5.5 E
(TCP is controlled by a windo)100.8 346.4 Q 1.43 -.715(w, a)-.275 H
(nd could send in a v).715 E(ery b)-.165 E
(ursty pattern, in the absence of)-.22 E(rate-based pacing.)100.8 359.4
Q/F1 11/Times-Bold@0 SF(8.)72 402 Q/F2 14/Times-Bold@0 SF
(Simulations of the V)5.5 E(oIP V)-1.4 E(ariant of TFRC)-1.288 E F0
-1.419(Vo)100.8 418.6 S
(IP mode for TFRC has been added to the NS simulator)1.419 E 2.75(,a)
-.44 G(nd is illustrated in the)-2.75 E -.275(va)100.8 431.6 S
(lidation test "./test-all-friendly" in the directory tcl/tests.).275 E
F1(8.1.)72 457.6 Q/F3 13/Times-Bold@0 SF -.13(Pa)5.5 G(ck).13 E(et Dr)
-.13 E(opping Beha)-.234 E(vior at Routers)-.325 E F0(The def)100.8
474.2 Q(ault TFRC, without the V)-.11 E(oIP v)-1.419 E(ariant, w)-.275 E
(as designed for rough f)-.11 E(airness with TCP)-.11 E 2.75(,f)-1.221 G
(or)-2.75 E(TFRC and TCP \215o)100.8 487.2 Q(ws with the same pack)-.275
E(et size, and e)-.11 E(xperiencing the same pack)-.165 E(et drop)-.11 E
2.75(rate. When)100.8 500.2 R(the issue of f)2.75 E
(airness between \215o)-.11 E(ws with dif)-.275 E(ferent pack)-.275 E
(ets sizes is addressed, it)-.11 E(matters whether the pack)100.8 513.2
Q(et drop rates e)-.11 E(xperienced by the \215o)-.165 E
(ws is related to the pack)-.275 E(et size.)-.11 E(That is, are small V)
100.8 526.2 Q(oIP pack)-1.419 E(ets just as lik)-.11 E
(ely to be dropped as lar)-.11 E(ge TCP pack)-.198 E(ets, or are the)
-.11 E(smaller pack)100.8 539.2 Q(ets less lik)-.11 E
(ely to be dropped [WBL04]? And what is the relationship between)-.11 E
(the pack)100.8 552.2 Q(et-dropping beha)-.11 E
(vior of the path, and the loss e)-.22 E -.165(ve)-.275 G
(nt measurements of TFRC?).165 E(In our simulations of TCP \215o)100.8
568.8 Q(ws competing with a V)-.275 E(oIP TFRC \215o)-1.419 E 2.75(ww)
-.275 G(ith smaller pack)-2.75 E(ets,)-.11 E
(in a scenario with a congested router with a DropT)100.8 581.8 Q
(ail queue, the V)-.88 E(oIP TCP \215o)-1.419 E 2.75(wr)-.275 G(ecei)
-2.75 E -.165(ve)-.275 G(s).165 E(more than its f)100.8 594.8 Q
(air share in bytes per second.)-.11 E(This is the case e)5.5 E -.165
(ve)-.275 G 2.75(nf).165 G(or a scenario where the)-2.75 E(TCP \215o)
100.8 607.8 Q(ws are the most aggressi)-.275 E -.165(ve)-.275 G 2.75(,w)
.165 G(ith SA)-2.75 E(CK TCP)-.44 E 2.75(,t)-1.221 G
(imestamps, and ECN.)-2.75 E(As e)100.8 624.4 Q(xpected, the pack)-.165
E(et dropping beha)-.11 E(vior can be v)-.22 E(aried by v)-.275 E
(arying the Acti)-.275 E .33 -.165(ve Q)-.275 H(ueue).165 E
(Management mechanism in the router)100.8 637.4 Q 5.5(.W)-.605 G
(hen the routers use RED in pack)-5.5 E(et mode, where)-.11 E
(each *pack)100.8 650.4 Q
(et* has the same probability of being dropped, the TFRC and TCP \215o)
-.11 E(ws recei)-.275 E -.165(ve)-.275 G(roughly the same pack)100.8
663.4 Q(et drop rate.)-.11 E
(In contrast, when the routers use RED in byte mode,)5.5 E(where each *\
byte* has the same probability of being dropped, the TFRC \215o)100.8
676.4 Q 2.75(ws)-.275 G(ees a much)-2.75 E(smaller pack)100.8 689.4 Q
(et drop rate than the TCP \215o)-.11 E
(ws, in simulations with moderate le)-.275 E -.165(ve)-.275 G(ls of).165
E(congestion.)100.8 702.4 Q(Flo)72 769 Q(yd/K)-.11 E 270.421
(ohler Section)-.385 F 2.75(8.1. [P)2.75 F(age 10])-.165 E 0 Cg EP
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(August 2005)2.75 E(February 2005)103.569 E 16.5(TCP TCP)180.8 85 R
13.75(TFRC TFRC)30.25 F 16.5(ND)156.05 98 S 2.75(ropRate Throughput)
-16.5 F 2.75(DropRate Throughput)11 F 11(--- --------)153.3 111 R 8.25
(---------- --------)5.5 F(----------)5.5 E 16.5(10 0.010)156.05 124 R
22(0.71 0.010)16.5 F(0.14)16.5 E 16.5(25 0.067)156.05 137 R 22
(0.61 0.063)16.5 F(0.32)16.5 E 16.5(50 0.180)156.05 150 R 22(0.37 0.162)
16.5 F(0.57)16.5 E 16.5(75 0.257)156.05 163 R 22(0.18 0.261)16.5 F(0.75)
16.5 E 16.5(100 0.295)153.3 176 R 22(0.15 0.407)16.5 F(0.82)16.5 E 16.5
(150 0.370)153.3 189 R 22(0.13 0.571)16.5 F(0.83)16.5 E -.88(Ta)150.55
215 S(ble 1:).88 E(Simulation Results with Drop-T)5.5 E(ail Queues.)-.88
E -.88(Ta)100.8 237.6 S(ble 1 abo).88 E .33 -.165(ve s)-.165 H(ho).165 E
(ws the results of simulations with N TCP \215o)-.275 E
(ws, with unlimited data to)-.275 E(send and 1460-byte pack)100.8 250.6
Q(ets, competing ag)-.11 E(ainst N V)-.055 E(oIP TFRC \215o)-1.419 E
(ws with 100 pack)-.275 E(ets per)-.11 E
(second of application data and 200-byte data pack)100.8 263.6 Q 2.75
(ets. N)-.11 F(ranges from 10 to 150, with a)2.75 E
(congested link of 10 Mbps, and each simulation is run for 100 seconds.)
100.8 276.6 Q(Each ro)5.5 E 2.75(wo)-.275 G 2.75(ft)-2.75 G(he)-2.75 E
(table gi)100.8 289.6 Q -.165(ve)-.275 G 2.75(st).165 G
(he result of a single simulation, gi)-2.75 E(ving the pack)-.275 E
(et drop rate for the TCP and)-.11 E(TFRC \215o)100.8 302.6 Q(ws, and t\
he fraction of the link bandwidth used by the N TCP and the N TFRC)-.275
E<8d6f>100.8 315.6 Q(ws respecti)-.275 E -.165(ve)-.275 G(ly).165 E 5.5
(.T)-.715 G(he simulations in the table abo)-5.5 E .33 -.165(ve u)-.165
H(se Drop-T).165 E(ail queues.)-.88 E(When N is)5.5 E
(small, congestion is lo)100.8 328.6 Q 1.43 -.715(w, a)-.275 H
(nd each V).715 E(oIP TFRC \215o)-1.419 E 2.75(wi)-.275 G 2.75(sl)-2.75
G(imited by the maximum data rate of)-2.75 E
(160 Kbps from the application.)100.8 341.6 Q
(In these cases, the TCP \215o)5.5 E(ws recei)-.275 E .33 -.165(ve c)
-.275 H(onsiderably more).165 E(bandwidth than the TFRC \215o)100.8
354.6 Q 2.75(ws. When)-.275 F 2.75(Ni)2.75 G 2.75(sl)-2.75 G(ar)-2.75 E
(ge, dri)-.198 E(ving the pack)-.275 E(et drop rate up to)-.11 E
(25-50%, the TFRC \215o)100.8 367.6 Q(ws recei)-.275 E .33 -.165(ve s)
-.275 H(igni\214cantly more bandwidth than the TCP \215o).165 E 2.75
(ws. In)-.275 F(each of these simulations, the TCP and TFRC \215o)100.8
380.6 Q(ws recei)-.275 E .33 -.165(ve s)-.275 H(ome).165 E
(what comparable pack)-.275 E(et)-.11 E(drop rates.)100.8 393.6 Q
(The SA)5.5 E(CK TCP connections in these simulations use the def)-.44 E
(ault parameters in)-.11 E(the NS simulator)100.8 406.6 Q 2.75(,w)-.44 G
(ith Limited T)-2.75 E(ransmit, and a minimum R)-.385 E .396 -.198(TO o)
-.66 H 2.75(f2).198 G(00 ms.)-2.75 E(Adding)5.5 E
(timestamps to the TCP connection didn')100.8 419.6 Q 2.75(tc)-.198 G
(hange the results appreciably)-2.75 E(.)-.715 E 16.5(TCP TCP)180.8
438.6 R 13.75(TFRC TFRC)30.25 F 16.5(ND)156.05 451.6 S 2.75
(ropRate Throughput)-16.5 F 2.75(DropRate Throughput)11 F 11
(--- --------)153.3 464.6 R 8.25(---------- --------)5.5 F(----------)
5.5 E 16.5(10 0.009)156.05 477.6 R 22(0.73 0.008)16.5 F(0.14)16.5 E 16.5
(25 0.051)156.05 490.6 R 22(0.60 0.037)16.5 F(0.33)16.5 E 16.5(50 0.166)
156.05 503.6 R 22(0.38 0.183)16.5 F(0.56)16.5 E 16.5(75 0.218)156.05
516.6 R 22(0.16 0.231)16.5 F(0.79)16.5 E 16.5(100 0.251)153.3 529.6 R 22
(0.12 0.392)16.5 F(0.87)16.5 E 16.5(150 0.326)153.3 542.6 R 22
(0.10 0.550)16.5 F(0.87)16.5 E -.88(Ta)150.55 568.6 S(ble 2:).88 E
(Simulation Results with RED Queues in P)5.5 E(ack)-.165 E(et Mode.)-.11
E -.88(Ta)100.8 587.6 S(ble 2 sho).88 E
(ws that the simulation results for RED queues in pack)-.275 E
(et mode, where each)-.11 E(pack)100.8 600.6 Q
(et is dropped with the same probability)-.11 E 2.75(,a)-.715 G
(re roughly comparble to those with Drop-T)-2.75 E(ail)-.88 E 2.75
(Queues. T)100.8 613.6 R(ables 1 and 2 suggest that the TCP response fu\
nction used in TFRC could be)-.88 E(modi\214ed to gi)100.8 626.6 Q .33
-.165(ve m)-.275 H(ore realistic v).165 E
(alues for TCP throughput at higher pack)-.275 E(et drop rates.)-.11 E
-.88(We)5.5 G(ran these simulations using ECN and TCP timestamps, with \
little change in the o)100.8 639.6 Q -.165(ve)-.165 G(rall).165 E
(results.)100.8 652.6 Q(Flo)72 769 Q(yd/K)-.11 E 270.421(ohler Section)
-.385 F 2.75(8.1. [P)2.75 F(age 11])-.165 E 0 Cg EP
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(August 2005)2.75 E(February 2005)103.569 E 16.5(TCP TCP)180.8 85 R
13.75(TFRC TFRC)30.25 F 16.5(ND)156.05 98 S 2.75(ropRate Throughput)
-16.5 F 2.75(DropRate Throughput)11 F 11(--- --------)153.3 111 R 8.25
(---------- --------)5.5 F(----------)5.5 E 16.5(10 0.009)156.05 124 R
22(0.72 0.008)16.5 F(0.14)16.5 E 16.5(25 0.049)156.05 137 R 22
(0.60 0.020)16.5 F(0.33)16.5 E 16.5(50 0.138)156.05 150 R 22(0.29 0.031)
16.5 F(0.65)16.5 E 16.5(75 0.181)156.05 163 R 22(0.12 0.168)16.5 F(0.83)
16.5 E 16.5(100 0.242)153.3 176 R 22(0.11 0.356)16.5 F(0.85)16.5 E 16.5
(150 0.323)153.3 189 R 22(0.09 0.536)16.5 F(0.87)16.5 E -.88(Ta)150.55
215 S(ble 3:).88 E(Simulation Results with RED Queues in Byte Mode.)5.5
E -.88(Ta)100.8 234 S(ble 3 sho).88 E(ws simulation results for RED que\
ues in byte mode, where the router tak)-.275 E(es the)-.11 E(pack)100.8
247 Q(et size into account in deciding whether or not to drop a pack)
-.11 E 2.75(et. Ag)-.11 F(ain, for higher)-.055 E -.275(va)100.8 260 S
(lues of N, the V).275 E(oIP TFRC \215o)-1.419 E 2.75(wr)-.275 G(ecei)
-2.75 E -.165(ve)-.275 G 2.75(sm).165 G
(ore than its share of the link bandwidth.)-2.75 E(The goal of the V)
100.8 276.6 Q(oIP v)-1.419 E(ariant of TFRC has been for the TCP \215o)
-.275 E(ws and the V)-.275 E(oIP TFRC)-1.419 E<8d6f>100.8 289.6 Q
(ws to ha)-.275 E .33 -.165(ve r)-.22 H(ough f).165 E
(airness in the sending rate in bps, in a scenario where each pack)-.11
E(et)-.11 E(recei)100.8 302.6 Q -.165(ve)-.275 G 2.75(sr).165 G
(oughly the same probability of being dropped.)-2.75 E
(In a scenario where lar)5.5 E(ge pack)-.198 E(ets)-.11 E(are more lik)
100.8 315.6 Q(ely to be dropped than small pack)-.11 E
(ets, or where \215o)-.11 E(ws with a b)-.275 E(ursty sending rate)-.22
E(are more lik)100.8 328.6 Q(ely to ha)-.11 E .33 -.165(ve p)-.22 H(ack)
.165 E(ets dropped than are \215o)-.11 E
(ws with a smooth sending rate, \215o)-.275 E(ws)-.275 E(using the V)
100.8 341.6 Q(oIP v)-1.419 E(ariant of TFRC could recei)-.275 E .33
-.165(ve m)-.275 H(ore bandwidth than competing TCP \215o).165 E(ws.)
-.275 E(Although the V)100.8 358.2 Q(oIP v)-1.419 E
(ariant of TFRC doesn')-.275 E 2.75(tr)-.198 G
(equire that applications are limited by a)-2.75 E
(maximum sending rate, in f)100.8 371.2 Q(act V)-.11 E(oIP \215o)-1.419
E(ws do ha)-.275 E .33 -.165(ve s)-.22 H(uch a limitation.).165 E
(As illustrated in the)5.5 E(simulations by T)100.8 384.2 Q
(om Phelan, this complicates the issue of e)-.88 E(xploring the f)-.165
E(airness between)-.11 E(TCP and V)100.8 397.2 Q(oIP TFRC \215o)-1.419 E
(ws.)-.275 E(In addition, for V)100.8 413.8 Q(oIP TFRC \215o)-1.419 E
(ws with a maximum sending rate of 96 Kbps, or with a)-.275 E
(smaller maximum sending rate, V)100.8 426.8 Q
(oIP TFRC only reduces the sending rate of these \215o)-1.419 E(ws)-.275
E(when the pack)100.8 439.8 Q(et drop rate is f)-.11 E(airly high.)-.11
E(In this re)5.5 E(gime, the performance of TFRC is v)-.165 E(ery)-.165
E(much determined by the accurac)100.8 452.8 Q 2.75(yo)-.165 G 2.75(ft)
-2.75 G(he TCP response function in representing the actual)-2.75 E
(sending rate of a TCP connection.)100.8 465.8 Q(In this re)5.5 E
(gime of high pack)-.165 E(et drop rates, the)-.11 E
(performance of the TCP connection is v)100.8 478.8 Q(ery much af)-.165
E(fected by the TCP algorithm \(e.g.,)-.275 E(SA)100.8 491.8 Q
(CK or not\), by the use of timestamps and/or of ECN, by the minimum R)
-.44 E -.198(TO)-.66 G 2.75(,b).198 G 2.75(yt)-2.75 G(he use)-2.75 E
(or not of Limited T)100.8 504.8 Q(ransmit, and the lik)-.385 E 2.75
(e. Thus,)-.11 F(for simulations in this re)2.75 E(gime, there are)-.165
E(man)100.8 517.8 Q 2.75(yp)-.165 G(arameters to consider)-2.75 E 8.25
(.I)-.605 G 2.75(ti)-8.25 G 2.75(sg)-2.75 G
(ood to insure that simulations e)-2.75 E(xploring f)-.165 E(airness)
-.11 E(include the e)100.8 530.8 Q(xploration of f)-.165 E
(airness with the most aggressi)-.11 E .33 -.165(ve T)-.275 H
(CP mechanisms conformance).165 E
(with the current standards, that is, SA)100.8 543.8 Q
(CK TCP using timestamps, ECN, Limited T)-.44 E(ransmit,)-.385 E
(and a minimum R)100.8 556.8 Q .396 -.198(TO o)-.66 H 2.75(f1).198 G
(00-200 ms.)-2.75 E/F1 11/Times-Bold@0 SF(9.)72 582.8 Q/F2 14
/Times-Bold@0 SF(Simulations of F)5.5 E(aster Restart)-.35 E F0(TB)100.8
599.4 Q(A)-.385 E F1(10.)72 625.4 Q F2(Implementation Issues)5.5 E F0
(TB)100.8 642 Q(A)-.385 E F1(11.)72 668 Q F2(Security Considerations)5.5
E F0(TB)100.8 684.6 Q(A)-.385 E(Flo)72 769 Q(yd/K)-.11 E 273.171
(ohler Section)-.385 F 2.75(11. [P)2.75 F(age 12])-.165 E 0 Cg EP
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(August 2005)2.75 E(February 2005)103.569 E/F1 11/Times-Bold@0 SF(12.)72
85 Q/F2 14/Times-Bold@0 SF(IAN)5.5 E 3.5(AC)-.28 G(onsiderations)-3.5 E
F0(There are no IAN)100.8 101.6 Q 2.75(Ac)-.385 G
(onsiderations in this document.)-2.75 E F1(13.)72 127.6 Q F2(Thanks)5.5
E F0 1.76 -.88(We t)100.8 144.2 T(hank T).88 E
(om Phelan for discussions of the V)-.88 E(oIP v)-1.419 E
(ariant of TFRC and for his paper)-.275 E -.165(ex)100.8 157.2 S
(ploring the f).165 E(airness between TCP and V)-.11 E(oIP TFRC \215o)
-1.419 E 2.75(ws. W)-.275 F 2.75(ea)-.88 G(lso thank the DCCP)-2.75 E
-.88(Wo)100.8 170.2 S(rking Group for feedback and discussions.).88 E F2
(Normati)72 196.2 Q .28 -.14(ve R)-.14 H(efer).14 E(ences)-.252 E F0
([RFC 2119] S. Bradner)100.8 212.8 Q 2.75(.K)-.605 G .33 -.165(ey W)
-3.025 H(ords F)-.715 E(or Use in RFCs to Indicate Requirement Le)-.165
E -.165(ve)-.275 G(ls. RFC).165 E(2119.)129.6 225.8 Q([RFC 2434] T)100.8
242.4 Q 2.75(.N)-.814 G(arten and H. Alv)-2.75 E 2.75
(estrand. Guidelines)-.165 F(for Writing an IAN)2.75 E 2.75(AC)-.385 G
(onsiderations)-2.75 E(Section in RFCs.)129.6 255.4 Q(RFC 2434.)5.5 E
([RFC 2581] M. Allman, V)100.8 272 Q 2.75(.P)-1.419 G(axson, and W)
-2.915 E 2.75(.S)-1.012 G(te)-2.75 E -.165(ve)-.275 G 2.75(ns. TCP).165
F(Congestion Control.)2.75 E(RFC 2581.)5.5 E([RFC 3448] M. Handle)100.8
288.6 Q 1.43 -.715(y, S)-.165 H 2.75(.F).715 G(lo)-2.75 E(yd, J. P)-.11
E(adh)-.165 E(ye, and J. W)-.055 E(idmer)-.44 E 2.75(,T)-.44 G
(CP Friendly Rate Control)-2.75 E(\(TFRC\): Protocol Speci\214cation, R\
FC 3448, Proposed Standard, January 2003.)129.6 301.6 Q F2(Inf)72 327.6
Q(ormati)-.35 E .28 -.14(ve R)-.14 H(efer).14 E(ences)-.252 E F0
([CCID 3 PR)100.8 344.2 Q(OFILE] S. Flo)-.44 E(yd, E. K)-.11 E(ohler)
-.385 E 2.75(,a)-.44 G(nd J. P)-2.75 E(adh)-.165 E 2.75(ye. Pro\214le)
-.055 F(for DCCP Congestion)2.75 E
(Control ID 3: TFRC Congestion Control.)129.6 357.2 Q
(draft-ietf-dccp-ccid3-06.txt, w)5.5 E(ork in)-.11 E
(progress, October 2004.)129.6 370.2 Q([DCCP] E. K)100.8 386.8 Q(ohler)
-.385 E 2.75(,M)-.44 G 2.75(.H)-2.75 G(andle)-2.75 E 1.43 -.715(y, a)
-.165 H(nd S. Flo).715 E 2.75(yd. Datagram)-.11 F
(Congestion Control Protocol,)2.75 E(draft-ietf-dccp-spec-08.txt, w)
129.6 399.8 Q(ork in progress, October 2004.)-.11 E([JF)100.8 416.4 Q
(AS05] A. Jain, S. Flo)-.814 E(yd, M. Allman, and P)-.11 E 2.75(.S)
-1.221 G 2.75(arolahti. Quick-Start)-2.75 F(for TCP and IP)2.75 E(.)
-1.221 E(Internet-draft draft-amit-quick-start-04.txt, w)129.6 429.4 Q
(ork in progress, February 2004.)-.11 E
([MAF04] A. Medina, M. Allman, and A. Flo)100.8 446 Q
(yd, Measuring the Ev)-.11 E(olution of T)-.22 E(ransport)-.385 E
(Protocols in the Internet, May 2004, URL "http://www)129.6 459 Q(.icir)
-.715 E(.or)-.605 E(g/tbit/".)-.198 E([P04] T)100.8 475.6 Q 2.75(.P)
-.814 G(helan, TFRC with Self-Limiting Sources, October 2004.)-2.75 E
(URL)5.5 E("http://www)129.6 488.6 Q(.phelan-4.com/dccp/".)-.715 E
([RFC 2861] M. Handle)100.8 505.2 Q 1.43 -.715(y, J)-.165 H 2.75(.P).715
G(adh)-2.915 E(ye, and S. Flo)-.055 E 2.75(yd. TCP)-.11 F(Congestion W)
2.75 E(indo)-.44 E 2.75(wV)-.275 G(alidation.)-3.971 E
(RFC 2861, June 2000.)129.6 518.2 Q([RFC 3714] S. Flo)100.8 534.8 Q
(yd and J. K)-.11 E(empf, Editors.)-.275 E(IAB Concerns Re)5.5 E -.055
(ga)-.165 G(rding Congestion Control).055 E(for V)129.6 547.8 Q(oice T)
-1.419 E(raf)-.385 E(\214c in the Internet.)-.275 E(RFC 3714.)5.5 E
([WBL04] J. W)100.8 564.4 Q(idmer)-.44 E 2.75(,C)-.44 G 2.75(.B)-2.75 G
(outremans, and Jean-Yv)-2.75 E(es Le Boudec.)-.165 E
(Congestion Control for)5.5 E(Flo)129.6 577.4 Q(ws with V)-.275 E
(ariable P)-1.221 E(ack)-.165 E(et Size, T)-.11 E(echnical Report.)-.77
E F2 -.7(Au)72 603.4 S(thors' Addr).7 E(esses)-.252 E F0(Sally Flo)100.8
620 Q(yd <\215o)-.11 E(yd@icir)-.11 E(.or)-.605 E(g>)-.198 E
(ICSI Center for Internet Research)100.8 633 Q
(1947 Center Street, Suite 600)100.8 646 Q(Berk)100.8 659 Q(ele)-.11 E
1.43 -.715(y, C)-.165 H 2.75(A9).715 G(4704)-2.75 E(USA)100.8 672 Q
(Eddie K)100.8 688.6 Q(ohler <k)-.385 E(ohler@cs.ucla.edu>)-.11 E
(4531C Boelter Hall)100.8 701.6 Q(UCLA Computer Science Department)100.8
714.6 Q(Flo)72 769 Q(yd/K)-.11 E 328.171(ohler [P)-.385 F(age 13])-.165
E 0 Cg EP
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(August 2005)2.75 E(February 2005)103.569 E(Los Angeles, CA 90095)100.8
85 Q(USA)100.8 98 Q/F1 11/Times-Bold@0 SF(14.)72 124 Q/F2 14
/Times-Bold@0 SF(Related W)5.5 E(ork on V)-1.05 E(oIP V)-1.4 E
(ariants of TFRC)-1.288 E F0(Other proposals for v)100.8 150 Q
(ariants of TFRC for application with v)-.275 E(ariable pack)-.275 E
(et sizes include)-.11 E([WBL04]. [WBL04] ar)100.8 163 Q
(gues that adapting TFRC for v)-.198 E(ariable pack)-.275 E
(et sizes by just using the)-.11 E(pack)100.8 176 Q
(et size of a reference TCP \215o)-.11 E 2.75(wi)-.275 G 2.75(nt)-2.75 G
(he TFRC equation w)-2.75 E(ould not suf)-.11 E(\214ce in the high-)
-.275 E(pack)100.8 189 Q(et-loss re)-.11 E
(gime; such a modi\214ed TFRC w)-.165 E(ould ha)-.11 E .33 -.165(ve a s)
-.22 H(trong bias in f).165 E -.22(avo)-.11 G 2.75(ro).22 G 2.75(fs)
-2.75 G(maller)-2.75 E(pack)100.8 202 Q(ets, because multiple lost pack)
-.11 E(ets in a single round-trip time w)-.11 E(ould be aggre)-.11 E
-.055(ga)-.165 G(ted into).055 E 2.75(as)100.8 215 S(ingle pack)-2.75 E
(et loss.)-.11 E(\(W)5.5 E 2.75(en)-.88 G(ote that the V)-2.75 E(oIP V)
-1.419 E(ariant proposed in our document dif)-1.221 E(fers from)-.275 E
(the stra)100.8 228 Q 2.75(wp)-.165 G
(roposal discussed in [WBL04] in that in our V)-2.75 E(oIP V)-1.419 E
(ariant, the allo)-1.221 E(wed)-.275 E
(bandwidth includes the bandwidth used by pack)100.8 241 Q
(et headers; and a minimum interv)-.11 E(al of 10)-.275 E
(ms between pack)100.8 254 Q(ets is enforced.\))-.11 E
([WBL04] proposes modifying the loss measurement)5.5 E
(process to account for the bias in f)100.8 267 Q -.22(avo)-.11 G 2.75
(ro).22 G 2.75(fs)-2.75 G(maller pack)-2.75 E(ets.)-.11 E
([WBL04] produces both a byte-mode and a pack)100.8 293 Q(et-mode v)-.11
E(ariant of the TFRC transport)-.275 E(protocol, for connections o)100.8
306 Q -.165(ve)-.165 G 2.75(rp).165 G(aths with per)-2.75 E
(-byte and per)-.22 E(-pack)-.22 E(et dropping respecti)-.11 E -.165(ve)
-.275 G(ly).165 E(.)-.715 E 1.76 -.88(We w)100.8 319 T(ould ar).77 E
(gue that in the absence of transport-le)-.198 E -.165(ve)-.275 G 2.75
(lm).165 G(echanisms for determining whether)-2.75 E(the pack)100.8 332
Q(et dropping in the netw)-.11 E(ork is per)-.11 E(-pack)-.22 E(et, per)
-.11 E(-byte, or some)-.22 E(where in between, a)-.275 E
(single TFRC implementation is needed that gi)100.8 345 Q -.165(ve)-.275
G 2.75(sr).165 G(oughly acceptable beha)-2.75 E(vior)-.22 E 2.75(,t)-.44
G 2.75(ot)-2.75 G(he)-2.75 E(connection and to the netw)100.8 358 Q
(ork as a whole, on paths with both per)-.11 E(-byte and per)-.22 E
(-pack)-.22 E(et)-.11 E
(dropping \(and on paths with multiple congested routers, some with per)
100.8 371 Q(-byte dropping)-.22 E(mechanisms, some with per)100.8 384 Q
(-pack)-.22 E(et dropping mechanisms, and some with dropping)-.11 E
(mechanisms that lie some)100.8 397 Q(where between per)-.275 E
(-byte and per)-.22 E(-pack)-.22 E(et\).)-.11 E F2
(Full Copyright Statement)72 436 Q F0(Cop)100.8 452.6 Q
(yright \(C\) The Internet Society 2004.)-.11 E
(This document is subject to the rights, licenses)5.5 E
(and restrictions contained in BCP 78, and e)100.8 465.6 Q
(xcept as set forth therein, the authors retain all)-.165 E
(their rights.)100.8 478.6 Q
(This document and the information contained herein are pro)100.8 495.2
Q(vided on an "AS IS" basis and)-.165 E(THE CONTRIB)100.8 508.2 Q(UT)
-.11 E(OR, THE ORGANIZA)-.198 E(TION HE/SHE REPRESENTS OR IS)-1.221 E
(SPONSORED BY \(IF ANY\), THE INTERNET SOCIETY AND THE INTERNET)100.8
521.2 Q(ENGINEERING T)100.8 534.2 Q(ASK FORCE DISCLAIM ALL W)-1.023 E
(ARRANTIES, EXPRESS OR)-1.32 E(IMPLIED, INCLUDING B)100.8 547.2 Q(UT NO)
-.11 E 2.75(TL)-.44 G(IMITED T)-2.75 E 2.75(OA)-.198 G(NY W)-2.75 E
(ARRANTY THA)-1.32 E 2.75(TT)-1.221 G(HE USE)-2.75 E(OF THE INFORMA)
100.8 560.2 Q(TION HEREIN WILL NO)-1.221 E 2.75(TI)-.44 G
(NFRINGE ANY RIGHTS OR ANY)-2.75 E(IMPLIED W)100.8 573.2 Q
(ARRANTIES OF MERCHANT)-1.32 E(ABILITY OR FITNESS FOR A)-1.023 E -1.012
(PA)100.8 586.2 S -.66(RT)1.012 G(ICULAR PURPOSE.).66 E F2
(Intellectual Pr)72 612.2 Q(operty)-.252 E F0(The IETF tak)100.8 628.8 Q
(es no position re)-.11 E -.055(ga)-.165 G(rding the v).055 E
(alidity or scope of an)-.275 E 2.75(yI)-.165 G(ntellectual Property)
-2.75 E(Rights or other rights that might be claimed to pertain to the \
implementation or use of the)100.8 641.8 Q
(technology described in this document or the e)100.8 654.8 Q
(xtent to which an)-.165 E 2.75(yl)-.165 G(icense under such rights)
-2.75 E(might or might not be a)100.8 667.8 Q -.275(va)-.22 G
(ilable; nor does it represent that it has made an).275 E 2.75(yi)-.165
G(ndependent)-2.75 E(ef)100.8 680.8 Q(fort to identify an)-.275 E 2.75
(ys)-.165 G(uch rights.)-2.75 E
(Information on the procedures with respect to rights in)5.5 E
(RFC documents can be found in BCP 78 and BCP 79.)100.8 693.8 Q
(Copies of IPR disclosures made to the IETF Secretariat and an)100.8
710.4 Q 2.75(ya)-.165 G(ssurances of licenses to)-2.75 E(be made a)100.8
723.4 Q -.275(va)-.22 G(ilable, or the result of an attempt made to obt\
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(ohler [P)-.385 F(age 14])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 72.802(-DRAFT Expires:)-1.012 F
(August 2005)2.75 E(February 2005)103.569 E(permission for the use of s\
uch proprietary rights by implementers or users of this)100.8 85 Q(spec\
i\214cation can be obtained from the IETF on-line IPR repository at)
100.8 98 Q(http://www)100.8 111 Q(.ietf.or)-.715 E(g/ipr)-.198 E(.)-.605
E(The IETF in)100.8 127.6 Q(vites an)-.44 E 2.75(yi)-.165 G
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(op)-2.75 E(yrights, patents or)-.11 E
(patent applications, or other proprietary rights that may co)100.8
140.6 Q -.165(ve)-.165 G 2.75(rt).165 G(echnology that may be)-2.75 E
(required to implement this standard.)100.8 153.6 Q
(Please address the information to the IETF at ietf-)5.5 E(ipr@ietf.or)
100.8 166.6 Q(g.)-.198 E(Flo)72 769 Q(yd/K)-.11 E 328.171(ohler [P)-.385
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