One document matched: draft-floyd-tcp-highspeed-03.ps

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/F0 10/Courier-Bold@0 SF(Internet Engineering Task Force)72 85 Q
(Sally Floyd)180 E 318(INTERNET-DRAFT ICSI)72 98 R 162
(draft-floyd-tcp-highspeed-03.ps 29)72 111 R(June 2003)6 E
(Expires: December 2003)372 124 Q/F1 14/Times-Bold@0 SF(HighSpeed TCP f)
144.738 149 Q(or Lar)-.35 E(ge Congestion W)-.14 E(indo)-.252 E(ws)-.14
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366.6 Q(.ietf.or)-.715 E(g/ietf/1id-)-.198 E(abstracts.txt)100.8 379.6 Q
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(Abstract)267.534 450.6 Q F3(This document proposes HighSpeed TCP)97
486.2 Q 2.75(,am)-1.221 G(odi\214cation to TCP')-2.75 E 2.75(sc)-.605 G
(ongestion control)-2.75 E
(mechanism for use with TCP connections with lar)97 499.2 Q
(ge congestion windo)-.198 E 2.75(ws. The)-.275 F(congestion control me\
chanisms of the current Standard TCP constrains the congestion)97 512.2
Q(windo)97 525.2 Q(ws that can be achie)-.275 E -.165(ve)-.275 G 2.75
(db).165 G 2.75(yT)-2.75 G(CP in realistic en)-2.75 E 2.75
(vironments. F)-.44 F(or e)-.165 E(xample, for a)-.165 E
(Standard TCP connection with 1500-byte pack)97 538.2 Q
(ets and a 100 ms round-trip time,)-.11 E(achie)97 551.2 Q
(ving a steady-state throughput of 10 Gbps w)-.275 E(ould require an a)
-.11 E -.165(ve)-.22 G(rage congestion).165 E(windo)97 564.2 Q 2.75(wo)
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1.76 -.88(To a)5.5 H(ddress this).88 E(limitation of TCP)97 603.2 Q 2.75
(,t)-1.221 G(his document proposes HighSpeed TCP)-2.75 E 2.75(,a)-1.221
G(nd solicits)-2.75 E -.165(ex)97 616.2 S
(perimentation and feedback from the wider community).165 E(.)-.715 E
.396 -.198(TO B)97 642.2 T 2.75(ED).198 G(ELETED BY THE RFC EDIT)-2.75 E
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(dded a section on "Deplo)-2.75 E(yment issues.")-.11 E 2.75(*A)97 137 S
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(urstiness on short time scales".)-.22 E 2.75(*A)97 189 S
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(ence times.).198 E 2.75(*C)97 215 S
(lari\214ed that "log" is "log base 10".)-2.75 E 2.75(*C)97 241 S
(lari\214ed that W = Lo)-2.75 E(w_windo)-.275 E 2.75(wa)-.275 G
(nd W_1 = High_windo)-2.75 E 1.43 -.715(w, i)-.275 H 2.75(nt).715 G
(he equation for b\(w\).)-2.75 E(Changes from draft-\215o)97 267 Q
(yd-tcp-highspeed-01.txt:)-.11 E 2.75(*A)97 293 S(dded a section on "T)
-2.75 E(radeof)-.385 E(fs for Choosing Congestion Control P)-.275 E
(arameters".)-.165 E 2.75(*A)97 319 S
(dded mention of Scalable TCP from T)-2.75 E(om K)-.88 E(elly)-.275 E(.)
-.715 E(Changes from draft-\215o)97 345 Q(yd-tcp-highspeed-00.txt:)-.11
E 2.75(*A)97 371 S(dded a discussion on related w)-2.75 E
(ork about changing the PMTU.)-.11 E 2.75(*A)97 397 S
(dded a discussion of an alternate, linear response function.)-2.75 E
2.75(*A)97 423 S(dded a discussion of the TCP windo)-2.75 E 2.75(ws)
-.275 G(cale option.)-2.75 E 2.75(*A)97 449 S(dded a discussion of High\
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(response of N parallel TCP connections.)97 462 Q 2.75(*A)97 488 S
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(December 2003)2.75 E(June 2003)116.406 E/F1 13/Times-Bold@0 SF -1.196
(Ta)239.126 85 S(ble of Contents)1.196 E/F2 10/Times-Roman@0 SF
(1. Introduction.)97 123 Q F0 11(......................)1.06 G F2(4)11.5
E(2. The Problem Description.)97 135 Q F0 11(..................)4.4 G F2
(4)11.5 E(3. Design Guidelines.)97 147 Q F0 11(....................)3.84
G F2(5)11.5 E(4. Non-Goals.)97 159 Q F0 11(......................)6.62 G
F2(6)11.5 E(5. Modifying the TCP Response Function.)97 171 Q F0 11
(..............)3.27 G F2(7)11.5 E(6. F)97 183 Q
(airness Implications of the HighSpeed Response Function.)-.15 E F0 11
(........)5.94 G F2(9)11.5 E(7. T)97 195 Q
(ranslating the HighSpeed Response Function into Congestion Control P)
-.35 E(arameters.)-.15 E F0(.)7.54 E F2(11)17.5 E
(8. An alternate, linear response functions.)97 207 Q F0 11
(..............)6.37 G F2(13)6.5 E(9. T)97 219 Q(radeof)-.35 E
(fs for Choosing Congestion Control P)-.25 E(arameters.)-.15 E F0 11
(.........)8.08 G F2(15)6.5 E(9.1. The Number of Round-T)107 231 Q
(rip T)-.35 E(imes between Loss Ev)-.35 E(ents.)-.15 E F0 11(........)
.55 G F2(15)6.5 E(9.2. The Number of P)107 243 Q(ack)-.15 E
(et Drops per Loss Ev)-.1 E(ent, with Drop-T)-.15 E(ail.)-.8 E F0 11
(......)8.69 G F2(16)6.5 E(10. Related Issues)97 255 Q F0 11
(.....................)4.26 G F2(16)6.5 E(10.1. Slo)107 267 Q(w-Start.)
-.25 E F0 11(....................)12.97 G F2(16)6.5 E(10.2. Limiting b)
107 279 Q(urstiness on short time scales.)-.2 E F0 11(............)6.53
G F2(17)6.5 E(10.3. Other limitations on windo)107 291 Q 2.5(ws)-.25 G
(ize.)-2.5 E F0 11(..............)4.92 G F2(17)6.5 E
(10.4. Implementation issues.)107 303 Q F0 11(.................)7.03 G
F2(18)6.5 E(11. Deplo)97 315 Q(yment issues.)-.1 E F0 11
(...................)11.02 G F2(18)6.5 E(11.1. Deplo)107 327 Q
(yment issues of HighSpeed TCP)-.1 E F0 11(............)13.66 G F2(18)
6.5 E(11.2. Deplo)107 339 Q(yment issues of Scalable TCP)-.1 E F0 11
(.............)10.47 G F2(19)6.5 E(12. Related W)97 351 Q
(ork in HighSpeed TCP)-.8 E(.)-1.11 E F0 11(...............)9.78 G F2
(21)6.5 E(13. Relationship to other W)97 363 Q(ork.)-.8 E F0 11
(.................)5.89 G F2(22)6.5 E(14. Conclusions.)97 375 Q F0 11
(.....................)9.8 G F2(22)6.5 E(15. Ackno)97 387 Q(wledgements)
-.25 E F0 11(...................)10.07 G F2(23)6.5 E(16. Normati)97 399
Q .3 -.15(ve R)-.25 H(eferences).15 E F0 11(..................)13.71 G
F2(23)6.5 E(17. Informati)97 411 Q .3 -.15(ve R)-.25 H(eferences).15 E
F0 11(..................)9.27 G F2(23)6.5 E(18. Security Considerations)
97 423 Q F0 11(..................)7.17 G F2(25)6.5 E(19. IAN)97 435 Q
2.5(AC)-.35 G(onsiderations)-2.5 E F0 11(...................)2.11 G F2
(25)6.5 E(20. TCP')97 447 Q 2.5(sL)-.55 G(oss Ev)-2.5 E
(ent Rate in Steady-State)-.15 E F0 11(..............)1.76 G F2(25)6.5 E
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2.75(as)100.8 189 S(teady-state throughput of 10 Gbps w)-2.75 E
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-.88(To a)100.8 280 T(ddress this fundamental limitation of TCP and of \
the TCP response function \(the).88 E
(function mapping the steady-state pack)100.8 293 Q
(et drop rate to TCP')-.11 E 2.75(sa)-.605 G -.165(ve)-2.97 G
(rage sending rate in).165 E(pack)100.8 306 Q(ets per round-trip time\)\
, this document describes a modi\214ed TCP response function for)-.11 E
(re)100.8 319 Q(gimes with higher congestion windo)-.165 E 2.75
(ws. This)-.275 F(document also solicits e)2.75 E(xperimentation and)
-.165 E(feedback on HighSpeed TCP from the wider community)100.8 332 Q
(.)-.715 E(Because HighSpeed TCP')100.8 358 Q 2.75(sm)-.605 G
(odi\214ed response function w)-2.75 E(ould only tak)-.11 E 2.75(ee)-.11
G -.275(ff)-2.75 G(ect with higher).275 E(congestion windo)100.8 371 Q
(ws, HighSpeed TCP does not modify TCP beha)-.275 E(vior in en)-.22 E
(vironments with)-.44 E(mild to hea)100.8 384 Q
(vy congestion, and therefore does not introduce an)-.22 E 2.75(yn)-.165
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(ather than made as ad hoc decisions by indi)-2.75 E
(vidual implementors or)-.275 E(TCP senders.)100.8 436 Q
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449 Q(these congestion control mechanisms directly use the TCP response\
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(modifying the TCP response function.)100.8 631 Q F1(2.)72 670 Q F2
(The Pr)5.5 E(oblem Description.)-.252 E F0(This section describes the \
number of round-trip times between congestion e)100.8 696 Q -.165(ve)
-.275 G(nts required).165 E(for a Standard TCP \215o)100.8 709 Q 2.75
(wt)-.275 G 2.75(oa)-2.75 G(chie)-2.75 E .33 -.165(ve a)-.275 H 2.75(na)
.165 G -.165(ve)-2.97 G(rage throughput of B bps, gi).165 E -.165(ve)
-.275 G 2.75(np).165 G(ack)-2.75 E(ets of D)-.11 E
(bytes and a round-trip time of R seconds.)100.8 722 Q 2.75(Ac)5.5 G
(ongestion e)-2.75 E -.165(ve)-.275 G(nt refers to a windo).165 E 2.75
(wo)-.275 G 2.75(fd)-2.75 G(ata)-2.75 E(Flo)72 769 Q 317.391(yd Section)
-.11 F 2.75(2. [P)2.75 F(age 4])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E
(with one or more dropped or ECN-mark)100.8 85 Q(ed pack)-.11 E
(ets \(where ECN stands for Explicit)-.11 E
(Congestion Noti\214cation\).)100.8 98 Q(From Appendix A, achie)100.8
124 Q(ving an a)-.275 E -.165(ve)-.22 G
(rage TCP throughput of B bps requires a loss e).165 E -.165(ve)-.275 G
(nt at).165 E(most e)100.8 137 Q -.165(ve)-.275 G
(ry BR/\(12D\) round-trip times.).165 E(This is illustrated in T)5.5 E
(able 1, for R = 0.1 seconds)-.88 E(and D = 1500 bytes.)100.8 150 Q
(The table also gi)5.5 E -.165(ve)-.275 G 2.75(st).165 G(he a)-2.75 E
-.165(ve)-.22 G(rage congestion windo).165 E 2.75(wWo)-.275 G 2.75(fB)
-2.75 G(R/\(8D\),)-2.75 E(and the steady-state pack)100.8 163 Q
(et drop rate P of 1.5/W^2.)-.11 E(TCP Throughput \(Mbps\))103.55 189 Q
-.66(RT)8.25 G(Ts Between Losses).66 E 19.25(WP)13.75 G 5.5
(--------------------- ------------------- ----)103.55 202 R(-----)11 E
55(15)131.05 215 S 33(.5 8.3)-55 F(0.02)11 E 49.5(10 55.5)128.3 228 R
8.25(83.3 0.0002)33 F 46.75(100 555.5)125.55 241 R 8.25(833.3 0.000002)
30.25 F 44(1000 5555.5)122.8 254 R 8.25(8333.3 0.00000002)27.5 F 41.25
(10000 55555.5)120.05 267 R 8.25(83333.3 0.0000000002)24.75 F -.88(Ta)
100.8 293 S(ble 1: R).88 E(TTs Between Congestion Ev)-.66 E
(ents for Standard TCP)-.165 E 2.75(,f)-1.221 G(or 1500-Byte P)-2.75 E
(ack)-.165 E(ets and a)-.11 E(Round-T)100.8 306 Q(rip T)-.385 E
(ime of 0.1 Seconds.)-.385 E(This document proposes HighSpeed TCP)100.8
332 Q 2.75(,am)-1.221 G(inimal modi\214cation to TCP')-2.75 E 2.75(si)
-.605 G(ncrease and)-2.75 E
(decrease parameters, for TCP connections with lar)100.8 345 Q
(ger congestion windo)-.198 E(ws, to allo)-.275 E 2.75(wT)-.275 G(CP)
-2.75 E(to achie)100.8 358 Q .33 -.165(ve h)-.275 H(igh throughput with\
 more realistic requirements for the steady-state pack).165 E(et)-.11 E
(drop rate.)100.8 371 Q(Equi)5.5 E -.275(va)-.275 G(lently).275 E 2.75
(,H)-.715 G
(ighSpeed TCP has more realistic requirements for the number of)-2.75 E
(round-trip times between loss e)100.8 384 Q -.165(ve)-.275 G(nts.).165
E/F1 11/Times-Bold@0 SF(3.)72 423 Q/F2 14/Times-Bold@0 SF
(Design Guidelines.)5.5 E F0(Our proposal for HighSpeed TCP is moti)
100.8 449 Q -.275(va)-.275 G(ted by the follo).275 E(wing requirements:)
-.275 E 2.75(*A)100.8 475 S(chie)-2.75 E .33 -.165(ve h)-.275 H(igh per)
.165 E(-connection throughput without requiring unrealistically lo)-.22
E 2.75(wp)-.275 G(ack)-2.75 E(et loss)-.11 E(rates.)100.8 488 Q 2.75(*R)
100.8 514 S(each high throughput reasonably quickly when in slo)-2.75 E
(w-start.)-.275 E 2.75(*R)100.8 540 S(each high throughput without o)
-2.75 E -.165(ve)-.165 G(rly long delays when reco).165 E -.165(ve)-.165
G(ring from multiple).165 E(retransmit timeouts, or when ramping-up fro\
m a period with small congestion windo)100.8 553 Q(ws.)-.275 E 2.75(*N)
100.8 579 S 2.75(oa)-2.75 G
(dditional feedback or support required from routers:)-2.75 E -.165(Fo)
100.8 605 S 2.75(re).165 G(xample, the goal is for acceptable performan\
ce in both ECN-capable and non-ECN-)-2.915 E(capable en)100.8 618 Q
(vironments, and with Drop-T)-.44 E(ail as well as with Acti)-.88 E .33
-.165(ve Q)-.275 H(ueue Management such).165 E(as RED in the routers.)
100.8 631 Q 2.75(*N)100.8 657 S 2.75(oa)-2.75 G
(dditional feedback required from TCP recei)-2.75 E -.165(ve)-.275 G
(rs.).165 E 2.75(*T)100.8 683 S(CP-compatible performance in en)-2.75 E
(vironments with moderate or high congestion:)-.44 E(Equi)100.8 709 Q
-.275(va)-.275 G(lently).275 E 2.75(,t)-.715 G
(he requirement is that there be no additional load on the netw)-2.75 E
(ork \(in terms of)-.11 E(increased pack)100.8 722 Q
(et drop rates\) in en)-.11 E
(vironments with moderate or high congestion.)-.44 E(Flo)72 769 Q
317.391(yd Section)-.11 F 2.75(3. [P)2.75 F(age 5])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E 2.75(*P)100.8 85 S
(erformance at least as good as Standard TCP in en)-2.75 E
(vironments with moderate or high)-.44 E(congestion.)100.8 98 Q 2.75(*A)
100.8 124 S(cceptable transient performance, in terms of increases in t\
he congestion windo)-2.75 E 2.75(wi)-.275 G 2.75(no)-2.75 G(ne)-2.75 E
(round-trip time, responses to se)100.8 137 Q -.165(ve)-.275 G
(re congestion, and con).165 E -.165(ve)-.44 G -.198(rg).165 G
(ence times to f).198 E(airness.)-.11 E(Currently)100.8 163 Q 2.75(,u)
-.715 G(sers wishing to achie)-2.75 E .33 -.165(ve t)-.275 H
(hroughputs of 1 Gbps or more typically open up).165 E(multiple TCP con\
nections in parallel, or use MulTCP [CO98,GRK99], which beha)100.8 176 Q
-.165(ve)-.22 G(s).165 E(roughly lik)100.8 189 Q 2.75(et)-.11 G
(he aggre)-2.75 E -.055(ga)-.165 G(te of N virtual TCP connections.).055
E(While this approach suf)5.5 E(\214ces for)-.275 E
(the occasional user on well-pro)100.8 202 Q(visioned links, it lea)
-.165 E -.165(ve)-.22 G 2.75(st).165 G(he parameter N to be determined)
-2.75 E(by the user)100.8 215 Q 2.75(,a)-.44 G
(nd results in more aggressi)-2.75 E .33 -.165(ve p)-.275 H
(erformance and higher steady-state pack).165 E(et drop)-.11 E
(rates if used in en)100.8 228 Q
(vironments with periods of moderate or high congestion.)-.44 E 1.76
-.88(We b)5.5 H(elie).88 E .33 -.165(ve t)-.275 H(hat).165 E 2.75(an)
100.8 241 S .55 -.275(ew a)-2.75 H(pproach is needed that of).275 E
(fers more \215e)-.275 E(xibility)-.165 E 2.75(,m)-.715 G(ore ef)-2.75 E
(fecti)-.275 E -.165(ve)-.275 G(ly scales to a wide).165 E(range of a)
100.8 254 Q -.275(va)-.22 G(ilable bandwidths, and competes more f).275
E(airly with Standard TCP in congested)-.11 E(en)100.8 267 Q
(vironments.)-.44 E/F1 11/Times-Bold@0 SF(4.)72 306 Q/F2 14/Times-Bold@0
SF(Non-Goals.)5.5 E F0(The follo)100.8 332 Q(wing are e)-.275 E
(xplicitly *not* goals of our w)-.165 E(ork:)-.11 E 2.75(*N)100.8 358 S
(on-goal: TCP-compatible performance in en)-2.75 E(vironments with v)
-.44 E(ery lo)-.165 E 2.75(wp)-.275 G(ack)-2.75 E(et drop)-.11 E(rates.)
100.8 371 Q 1.76 -.88(We n)100.8 397 T
(ote that our proposal does not require, or deli).88 E -.165(ve)-.275 G
.88 -.44(r, T).165 H(CP-compatible performance in).44 E(en)100.8 410 Q
(vironments with v)-.44 E(ery lo)-.165 E 2.75(wp)-.275 G(ack)-2.75 E
(et drop rates, e.g., with pack)-.11 E(et loss rates of 10^-5 or 10^-6.)
-.11 E(As we discuss later in this document, we assume that Standard TC\
P is unable to mak)100.8 423 Q(e)-.11 E(ef)100.8 436 Q(fecti)-.275 E .33
-.165(ve u)-.275 H(se of the a).165 E -.275(va)-.22 G
(ilable bandwidth in en).275 E
(vironments with loss rates of 10^-6 in an)-.44 E(y)-.165 E(case, so th\
at it is acceptable and appropriate for HighSpeed TCP to perform more)
100.8 449 Q(aggressi)100.8 462 Q -.165(ve)-.275 G
(ly than Standard TCP is such an en).165 E(vironment.)-.44 E 2.75(*N)
100.8 488 S(on-goal: Ramping-up more quickly than allo)-2.75 E
(wed by slo)-.275 E(w-start.)-.275 E
(It is our belief that ramping-up more quickly than allo)100.8 514 Q
(wed by slo)-.275 E(w-start w)-.275 E(ould necessitate)-.11 E(more e)
100.8 527 Q(xplicit feedback from routers along the path.)-.165 E
(The proposal for HighSpeed TCP is)5.5 E
(focused on changes to TCP that could be ef)100.8 540 Q(fecti)-.275 E
-.165(ve)-.275 G(ly deplo).165 E(yed in the current Internet)-.11 E(en)
100.8 553 Q(vironment.)-.44 E 2.75(*N)100.8 579 S(on-goal: A)-2.75 E
-.22(vo)-.814 G(iding oscillations in en).22 E
(vironments with only one-w)-.44 E(ay)-.11 E 2.75(,l)-.715 G(ong-li)
-2.75 E -.165(ve)-.275 G 2.75<648d>.165 G -.275(ow)-2.75 G 2.75(sa).275
G(ll)-2.75 E(with the same round-trip times.)100.8 592 Q
(While we agree that attention to oscillatory beha)100.8 618 Q
(vior is useful, a)-.22 E -.22(vo)-.22 G(iding oscillations in).22 E
(aggre)100.8 631 Q -.055(ga)-.165 G(te throughput has not been our prim\
ary consideration, particularly for simpli\214ed).055 E(en)100.8 644 Q
(vironments limited to one-w)-.44 E(ay)-.11 E 2.75(,l)-.715 G(ong-li)
-2.75 E -.165(ve)-.275 G 2.75<648d>.165 G -.275(ow)-2.75 G 2.75(sa).275
G(ll with the same, lar)-2.75 E(ge round-trip times.)-.198 E
(Our assessment is that some oscillatory beha)100.8 657 Q
(vior in these e)-.22 E(xtreme en)-.165 E(vironments is an)-.44 E
(acceptable price to pay for the other bene\214ts of HighSpeed TCP)100.8
670 Q(.)-1.221 E(Flo)72 769 Q 317.391(yd Section)-.11 F 2.75(4. [P)2.75
F(age 6])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E/F1 11/Times-Bold@0 SF(5.)72 85
Q/F2 14/Times-Bold@0 SF(Modifying the TCP Response Function.)5.5 E F0
(The TCP response function, w = 1.2/sqrt\(p\), gi)100.8 111 Q -.165(ve)
-.275 G 2.75(sT).165 G(CP')-2.75 E 2.75(sa)-.605 G -.165(ve)-2.97 G
(rage congestion windo).165 E 2.75(wwi)-.275 G(n)-2.75 E(MSS-sized se)
100.8 124 Q(gments, as a function of the steady-state pack)-.165 E
(et drop rate p [FF98].)-.11 E(This TCP)5.5 E
(response function is a direct consequence of TCP')100.8 137 Q 2.75(sA)
-.605 G(dditi)-2.75 E .33 -.165(ve I)-.275 H(ncrease Multiplicati).165 E
-.165(ve)-.275 G
(Decrease \(AIMD\) mechanisms of increasing the congestion windo)100.8
150 Q 2.75(wb)-.275 G 2.75(yr)-2.75 G(oughly one)-2.75 E(se)100.8 163 Q
(gment per round-trip time in the absence of congestion, and halving th\
e congestion)-.165 E(windo)100.8 176 Q 2.75(wi)-.275 G 2.75(nr)-2.75 G
(esponse to a round-trip time with a congestion e)-2.75 E -.165(ve)-.275
G 2.75(nt. This).165 F(response function)2.75 E
(for Standard TCP is re\215ected in the table belo)100.8 189 Q 4.18
-.715(w. I)-.275 H 2.75(nt).715 G
(his proposal we restrict our attention)-2.75 E
(to TCP performance in en)100.8 202 Q(vironments with pack)-.44 E
(et loss rates of at most 10^-2, and so we can)-.11 E
(ignore the more comple)100.8 215 Q 2.75(xr)-.165 G
(esponse functions that are required to model TCP performance)-2.75 E
(in more congested en)100.8 228 Q(vironments with retransmit timeouts.)
-.44 E(From Appendix A, an a)5.5 E -.165(ve)-.22 G(rage).165 E
(congestion windo)100.8 241 Q 2.75(wo)-.275 G 2.75(fWc)-2.75 G
(orresponds to an a)-2.75 E -.165(ve)-.22 G
(rage of 2/3 W round-trip times between loss).165 E -2.365 -.275(ev e)
100.8 254 T(nts for Standard TCP \(with the congestion windo).275 E 2.75
(wv)-.275 G(arying from 2/3 W to 4/3 W\).)-3.025 E -.165(Pa)111.8 280 S
(ck).165 E(et Drop Rate P)-.11 E(Congestion W)8.25 E(indo)-.44 E 2.75
2.75(wW R)-.275 H(TTs Between Losses)-3.41 E 5.5
(------------------ -------------------)111.8 293 R(-------------------)
11 E 55(10^-2 12)131.05 306 R(8)44 E 55(10^-3 38)131.05 319 R(25)41.25 E
52.25(10^-4 120)131.05 332 R(80)41.25 E 52.25(10^-5 379)131.05 345 R
(252)38.5 E 49.5(10^-6 1200)131.05 358 R(800)38.5 E 49.5(10^-7 3795)
131.05 371 R(2530)35.75 E 46.75(10^-8 12000)131.05 384 R(8000)35.75 E
46.75(10^-9 37948)131.05 397 R(25298)33 E 41.25(10^-10 120000)131.05 410
R(80000)33 E -.88(Ta)100.8 436 S
(ble 2: TCP Response Function for Standard TCP).88 E 5.5(.T)-1.221 G
(he a)-5.5 E -.165(ve)-.22 G(rage congestion windo).165 E 2.75(wWi)-.275
G(n)-2.75 E(MSS-sized se)100.8 449 Q(gments is gi)-.165 E -.165(ve)-.275
G 2.75(na).165 G 2.75(saf)-2.75 G(unction of the pack)-2.75 E
(et drop rate P)-.11 E(.)-1.221 E 1.76 -.88(To s)100.8 475 T
(pecify a modi\214ed response function for HighSpeed TCP).88 E 2.75(,w)
-1.221 G 2.75(eu)-2.75 G(se three parameters,)-2.75 E(Lo)100.8 488 Q
(w_W)-.275 E(indo)-.44 E 1.43 -.715(w, H)-.275 H(igh_W).715 E(indo)-.44
E 1.43 -.715(w, a)-.275 H(nd High_P).715 E 5.5(.T)-1.221 G 2.75(oe)-6.38
G(nsure TCP compatibility)-2.75 E 2.75(,t)-.715 G(he HighSpeed)-2.75 E(\
response function uses the same response function as Standard TCP when \
the current)100.8 501 Q(congestion windo)100.8 514 Q 2.75(wi)-.275 G
2.75(sa)-2.75 G 2.75(tm)-2.75 G(ost Lo)-2.75 E(w_W)-.275 E(indo)-.44 E
1.43 -.715(w, a)-.275 H(nd uses the HighSpeed response function).715 E
(when the current congestion windo)100.8 527 Q 2.75(wi)-.275 G 2.75(sg)
-2.75 G(reater than Lo)-2.75 E(w_W)-.275 E(indo)-.44 E 4.18 -.715(w. I)
-.275 H 2.75(nt).715 G(his document we)-2.75 E(set Lo)100.8 540 Q(w_W)
-.275 E(indo)-.44 E 2.75(wt)-.275 G 2.75(o3)-2.75 G 2.75(8M)-2.75 G
(SS-sized se)-2.75 E(gments, corresponding to a pack)-.165 E
(et drop rate of 10^-3)-.11 E(for TCP)100.8 553 Q(.)-1.221 E 1.76 -.88
(To s)100.8 579 T(pecify the upper end of the HighSpeed response functi\
on, we specify the pack).88 E(et drop)-.11 E
(rate needed in the HighSpeed response function to achie)100.8 592 Q .33
-.165(ve a)-.275 H 2.75(na).165 G -.165(ve)-2.97 G
(rage congestion windo).165 E(w)-.275 E(of 83000 se)100.8 605 Q 2.75
(gments. This)-.165 F(is roughly the windo)2.75 E 2.75(wn)-.275 G
(eeded to sustain 10 Gbps throughput, for)-2.75 E 2.75(aT)100.8 618 S
(CP connection with the def)-2.75 E(ault pack)-.11 E
(et size and round-trip time used earlier in this)-.11 E 2.75
(document. F)100.8 631 R(or High_W)-.165 E(indo)-.44 E 2.75(ws)-.275 G
(et to 83000, we specify High_P of 10^-7; that is, with)-2.75 E
(HighSpeed TCP a pack)100.8 644 Q(et drop rate of 10^-7 allo)-.11 E
(ws the HighSpeed TCP connection to)-.275 E(achie)100.8 657 Q .33 -.165
(ve a)-.275 H 2.75(na).165 G -.165(ve)-2.97 G(rage congestion windo).165
E 2.75(wo)-.275 G 2.75(f8)-2.75 G(3000 se)-2.75 E 2.75(gments. W)-.165 F
2.75(eb)-.88 G(elie)-2.75 E .33 -.165(ve t)-.275 H(hat this loss rate)
.165 E(sets an achie)100.8 670 Q -.275(va)-.275 G(ble tar).275 E
(get for high-speed en)-.198 E(vironments, while still allo)-.44 E
(wing acceptable)-.275 E -.11(fa)100.8 683 S(irness for the HighSpeed r\
esponse function when competing with Standard TCP in).11 E(en)100.8 696
Q(vironments with pack)-.44 E(et drop rates of 10^-4 or 10^5.)-.11 E
-.165(Fo)100.8 722 S 2.75(rs).165 G(implicity)-2.75 E 2.75(,f)-.715 G
(or the HighSpeed response function we maintain the property that the)
-2.75 E(Flo)72 769 Q 317.391(yd Section)-.11 F 2.75(5. [P)2.75 F(age 7])
-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E(response function gi)100.8 85
Q -.165(ve)-.275 G 2.75(sas).165 G
(traight line on a log-log scale \(as does the response function for)
-2.75 E(Standard TCP)100.8 98 Q 2.75(,f)-1.221 G(or lo)-2.75 E 2.75(wt)
-.275 G 2.75(om)-2.75 G(oderate congestion\).)-2.75 E
(This results in the follo)5.5 E(wing response)-.275 E(function, for v)
100.8 111 Q(alues of the a)-.275 E -.165(ve)-.22 G
(rage congestion windo).165 E 2.75(wWg)-.275 G(reater than Lo)-2.75 E
(w_W)-.275 E(indo)-.44 E(w:)-.275 E 2.75(W=\()106.3 137 S(p/Lo)-2.75 E
(w_P\)^S Lo)-.275 E(w_W)-.275 E(indo)-.44 E -.715(w,)-.275 G(for Lo)
100.8 163 Q(w_P the pack)-.275 E(et drop rate corresponding to Lo)-.11 E
(w_W)-.275 E(indo)-.44 E 1.43 -.715(w, a)-.275 H(nd for S as follo).715
E(wing)-.275 E(constant [FRS02]:)100.8 176 Q 2.75(S=\()106.3 202 S
(log High_W)-2.75 E(indo)-.44 E 2.75(w-l)-.275 G(og Lo)-2.75 E(w_W)-.275
E(indo)-.44 E(w\)/\(log High_P - log Lo)-.275 E(w_P\).)-.275 E
(\(In this paper)100.8 228 Q 2.75(,")-.44 G
(log x" refers to the log base 10.\))-2.75 E -.165(Fo)5.5 G 2.75(re).165
G(xample, for Lo)-2.915 E(w_W)-.275 E(indo)-.44 E 2.75(ws)-.275 G
(et to 38,)-2.75 E(we ha)100.8 241 Q .33 -.165(ve L)-.22 H -.275(ow).165
G(_P of 10^-3 \(for compatibility with Standard TCP\).).275 E
(Thus, for High_W)5.5 E(indo)-.44 E(w)-.275 E
(set to 83000 and High_P set to 10^-7, we get the follo)100.8 254 Q
(wing response function:)-.275 E 2.75(W=0)106.3 280 S 96.25
(.12/p^0.835. \(1\))-2.75 F
(This HighSpeed response function is illustrated in T)100.8 306 Q
(able 3 belo)-.88 E 4.18 -.715(w. F)-.275 H(or HighSpeed TCP).55 E 2.75
(,t)-1.221 G(he)-2.75 E(number of round-trip times between losses, 1/\(\
pW\), equals 12.7 W^0.2, for W > 38)100.8 319 Q(se)100.8 332 Q(gments.)
-.165 E -.165(Pa)111.8 358 S(ck).165 E(et Drop Rate P)-.11 E
(Congestion W)8.25 E(indo)-.44 E 2.75 2.75(wW R)-.275 H
(TTs Between Losses)-3.41 E 5.5(------------------ -------------------)
111.8 371 R(-------------------)11 E 52.25(10^-2 12)131.05 384 R(8)52.25
E 52.25(10^-3 38)131.05 397 R(25)49.5 E 49.5(10^-4 263)131.05 410 R(38)
49.5 E 46.75(10^-5 1795 57)131.05 423 R 44(10^-6 12279)131.05 436 R(83)
49.5 E 44(10^-7 83981 123)131.05 449 R 41.25(10^-8 574356)131.05 462 R
(180)46.75 E 38.5(10^-9 3928088)131.05 475 R(264)46.75 E 33
(10^-10 26864653)131.05 488 R(388)46.75 E -.88(Ta)100.8 514 S
(ble 3: TCP Response Function for HighSpeed TCP).88 E 5.5(.T)-1.221 G
(he a)-5.5 E -.165(ve)-.22 G(rage congestion windo).165 E 2.75(wW)-.275
G(in MSS-sized se)100.8 527 Q(gments is gi)-.165 E -.165(ve)-.275 G 2.75
(na).165 G 2.75(saf)-2.75 G(unction of the pack)-2.75 E(et drop rate P)
-.11 E(.)-1.221 E 1.76 -.88(We b)100.8 553 T(elie).88 E .33 -.165(ve t)
-.275 H(hat the problem of backw).165 E
(ard compatibility with Standard TCP requires a)-.11 E(response functio\
n that is quite close to that of Standard TCP for loss rates of 10^-1, \
10^-2,)100.8 566 Q(or 10^-3.)100.8 579 Q 1.76 -.88(We b)5.5 H(elie).88 E
-.165(ve)-.275 G 2.75(,h).165 G -.275(ow)-2.75 G -2.365 -.275(ev e).275
H .88 -.44(r, t).275 H
(hat such stringent TCP-compatibility is not required for).44 E(smaller\
 loss rates, and that an appropriate response function is one that gi)
100.8 592 Q -.165(ve)-.275 G 2.75(sap).165 G(lausible)-2.75 E(pack)100.8
605 Q(et drop rate for a connection throughput of 10 Gbps.)-.11 E
(This also gi)5.5 E -.165(ve)-.275 G 2.75(sas).165 G(lo)-2.75 E(wly)
-.275 E(increasing number of round-trip times between loss e)100.8 618 Q
-.165(ve)-.275 G(nts as a function of a decreasing).165 E(pack)100.8 631
Q(et drop rate.)-.11 E(Another w)100.8 657 Q(ay to look at the HighSpee\
d response function is to consider that HighSpeed)-.11 E(TCP is roughly\
 emulating the congestion control response of N parallel TCP connection\
s,)100.8 670 Q(where N is initially one, and where N increases as a fun\
ction of the HighSpeed TCP')100.8 683 Q(s)-.605 E(congestion windo)100.8
696 Q 4.18 -.715(w. T)-.275 H
(hus for the HighSpeed response function in Equation \(1\) abo).715 E
-.165(ve)-.165 G 2.75(,t).165 G(he)-2.75 E(response function can be vie)
100.8 709 Q(wed as equi)-.275 E -.275(va)-.275 G
(lent to that of N\(W\) parallel TCP connections,).275 E(where N\(W\) v)
100.8 722 Q(aries as a function of the congestion windo)-.275 E 2.75(wW)
-.275 G 5.5(.R)-3.762 G(ecall that for a single)-5.5 E(Flo)72 769 Q
317.391(yd Section)-.11 F 2.75(5. [P)2.75 F(age 8])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 66.092(-DRAFT Expires:)-1.012 F
(December 2003)2.75 E(June 2003)116.406 E
(standard TCP connection, the a)100.8 85 Q -.165(ve)-.22 G
(rage congestion windo).165 E 2.75(we)-.275 G(quals 1.2/sqrt\(p\).)-2.75
E -.165(Fo)5.5 G 2.75(rN).165 G(parallel TCP connections, the aggre)
100.8 98 Q -.055(ga)-.165 G(te congestion windo).055 E 2.75(wf)-.275 G
(or the N connections equals)-2.75 E 2.75(N*1.2/sqrt\(p\). From)100.8
111 R
(the HighSpeed response function in Equation \(1\) and the relationship)
2.75 E(abo)100.8 124 Q -.165(ve)-.165 G 2.75(,w).165 G 2.75(ec)-2.75 G
(an deri)-2.75 E .33 -.165(ve t)-.275 H(he follo).165 E(wing:)-.275 E
(N\(W\) = 0.23*W^\(0.4\))103.55 150 Q(for N\(W\) the number of parallel\
 TCP connections emulated by the HighSpeed TCP)100.8 176 Q
(response function, and for N\(W\) >= 1.)100.8 189 Q(This is sho)5.5 E
(wn in T)-.275 E(able 4 belo)-.88 E -.715(w.)-.275 G(Congestion W)111.8
215 Q(indo)-.44 E 16.5 2.75(wW N)-.275 H(umber N\(W\) of P)-2.75 E
(arallel TCPs)-.165 E 22(------------------- -------------------------)
111.8 228 R 77(11)136.55 241 S 74.25(10 1)133.8 254 R 74.25(100 1.4)
131.05 267 R 74.25(1,000 3.6)125.55 280 R 74.25(10,000 9.2)122.8 293 R
71.5(100,000 23.0)120.05 306 R -.88(Ta)100.8 332 S(ble 4: Number N\(W\)\
 of parallel TCP connections roughly emulated by the HighSpeed).88 E
(TCP response function.)100.8 345 Q 1.76 -.88(We d)100.8 371 T 2.75(on)
.88 G(ot in this document attempt to seriously e)-2.75 E -.275(va)-.275
G(luate the HighSpeed response function).275 E(for congestion windo)
100.8 384 Q(ws greater than 100,000 pack)-.275 E 2.75(ets. W)-.11 F 2.75
(eb)-.88 G(elie)-2.75 E .33 -.165(ve t)-.275 H(hat we will learn more)
.165 E(about the requirements for sustaining the throughput of best-ef)
100.8 397 Q(fort connections in that)-.275 E(range as we g)100.8 410 Q
(ain more e)-.055 E(xperience with HighSpeed TCP with congestion windo)
-.165 E(ws of)-.275 E(thousands and tens of thousands of pack)100.8 423
Q 2.75(ets. There)-.11 F(also might be limitations to the per)2.75 E(-)
-.22 E(connection throughput that can be realistically achie)100.8 436 Q
-.165(ve)-.275 G 2.75(df).165 G(or best-ef)-2.75 E(fort traf)-.275 E
(\214c, in terms of)-.275 E(congestion windo)100.8 449 Q 2.75(wo)-.275 G
2.75(fh)-2.75 G(undreds of thousands of pack)-2.75 E
(ets or more, in the absence of)-.11 E
(additional support or feedback from the routers along the path.)100.8
462 Q/F1 11/Times-Bold@0 SF(6.)72 501 Q/F2 14/Times-Bold@0 SF -.35(Fa)
5.5 G(ir).35 E(ness Implications of the HighSpeed Response Function.)
-.21 E F0(The Standard and Highspeed Response Functions can be used dir\
ectly to infer the relati)100.8 527 Q -.165(ve)-.275 G -.11(fa)100.8 540
S(irness between \215o).11 E(ws using the tw)-.275 E 2.75(or)-.11 G
(esponse functions.)-2.75 E -.165(Fo)5.5 G 2.75(re).165 G(xample, gi)
-2.915 E -.165(ve)-.275 G 2.75(nap).165 G(ack)-2.75 E(et drop)-.11 E
(rate P)100.8 553 Q 2.75(,a)-1.221 G(ssume that Standard TCP has an a)
-2.75 E -.165(ve)-.22 G(rage congestion windo).165 E 2.75(wo)-.275 G
2.75(fW)-2.75 G(_Standard, and)-2.75 E(HighSpeed TCP has a higher a)
100.8 566 Q -.165(ve)-.22 G(rage congestion windo).165 E 2.75(wo)-.275 G
2.75(fW)-2.75 G 2.75(_HighSpeed. In)-2.75 F(this case, a)2.75 E
(single HighSpeed TCP connection is recei)100.8 579 Q
(ving W_HighSpeed/W_Standard times the)-.275 E(throughput of a single S\
tandard TCP connection competing in the same en)100.8 592 Q(vironment.)
-.44 E(This relati)100.8 618 Q .33 -.165(ve f)-.275 H
(airness is illustrated belo).055 E 2.75(wi)-.275 G 2.75(nT)-2.75 G
(able 5, for the parameters used for the)-3.63 E
(Highspeed response function in the section abo)100.8 631 Q -.165(ve)
-.165 G 5.5(.T).165 G(he second column gi)-5.5 E -.165(ve)-.275 G 2.75
(st).165 G(he relati)-2.75 E -.165(ve)-.275 G -.11(fa)100.8 644 S
(irness, for the steady-state pack).11 E
(et drop rate speci\214ed in the \214rst column.)-.11 E 1.76 -.88(To h)
5.5 H(elp).88 E(calibrate, the third column gi)100.8 657 Q -.165(ve)
-.275 G 2.75(st).165 G(he aggre)-2.75 E -.055(ga)-.165 G(te a).055 E
-.165(ve)-.22 G(rage congestion windo).165 E 2.75(wf)-.275 G(or the tw)
-2.75 E 2.75(oT)-.11 G(CP)-2.75 E(connections, and the fourth column gi)
100.8 670 Q -.165(ve)-.275 G 2.75(st).165 G(he bandwidth that w)-2.75 E
(ould be needed by the tw)-.11 E(o)-.11 E(connections to achie)100.8 683
Q .33 -.165(ve t)-.275 H(hat aggre).165 E -.055(ga)-.165 G(te windo).055
E 2.75(wa)-.275 G(nd pack)-2.75 E(et drop rate, gi)-.11 E -.165(ve)-.275
G 2.75(n1).165 G(00 ms round-)-2.75 E(trip times and 1500-byte pack)
100.8 696 Q(ets.)-.11 E(Flo)72 769 Q 317.391(yd Section)-.11 F 2.75
(6. [P)2.75 F(age 9])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E -.165(Pa)106.3 85 S(ck).165 E
(et Drop Rate P)-.11 E -.165(Fa)8.25 G 2.75(irness Aggre).165 F -.055
(ga)-.165 G(te W).055 E(indo)-.44 E 5.5(wB)-.275 G(andwidth)-5.5 E 5.5
(------------------ --------)106.3 98 R 2.75(---------------- ---------)
5.5 F 30.25(10^-2 1.0)125.55 111 R 19.25(24 2.8)38.5 F(Mbps)2.75 E 30.25
(10^-3 1.0)125.55 124 R 19.25(76 9.1)38.5 F(Mbps)2.75 E 30.25(10^-4 2.2)
125.55 137 R 16.5(383 45.9)35.75 F(Mbps)2.75 E 30.25(10^-5 4.7 2174)
125.55 150 R(260.8 Mbps)16.5 E 27.5(10^-6 10.2 13479)125.55 163 R
(1.6 Gbps)22 E 27.5(10^-7 22.1 87776)125.55 176 R(10.5 Gbps)19.25 E -.88
(Ta)100.8 202 S(ble 5: Relati).88 E .33 -.165(ve Fa)-.275 H
(irness between the HighSpeed and Standard Response Functions.).165 E
(Thus, for pack)100.8 241 Q(et drop rates of 10^-4, a \215o)-.11 E 2.75
(ww)-.275 G(ith the HighSpeed response function can)-2.75 E -.165(ex)
100.8 254 S(pect to recei).165 E .33 -.165(ve 2)-.275 H
(.2 times the throughput of a \215o).165 E 2.75(wu)-.275 G
(sing the Standard response function,)-2.75 E(gi)100.8 267 Q -.165(ve)
-.275 G 2.75(nt).165 G(he same round-trip times and pack)-2.75 E
(et sizes.)-.11 E -.44(Wi)5.5 G(th pack).44 E
(et drop rates of 10^-6 \(or)-.11 E(10^-7\), the unf)100.8 280 Q
(airness is more se)-.11 E -.165(ve)-.275 G(re, and we ha).165 E .33
-.165(ve e)-.22 H(ntered the re).165 E(gime where a Standard)-.165 E
(TCP connection requires at most one congestion e)100.8 293 Q -.165(ve)
-.275 G(nt e).165 E -.165(ve)-.275 G(ry 800 \(or 2530\) round-trip).165
E(times in order to mak)100.8 306 Q 2.75(eu)-.11 G(se of the a)-2.75 E
-.275(va)-.22 G(ilable bandwidth.).275 E(Our judgement w)5.5 E
(ould be that there)-.11 E(are not a lot of TCP connections ef)100.8 319
Q(fecti)-.275 E -.165(ve)-.275 G(ly operating in this re).165 E
(gime today)-.165 E 2.75(,w)-.715 G(ith congestion)-2.75 E(windo)100.8
332 Q(ws of thousands of pack)-.275 E
(ets, and that therefore the bene\214ts of the HighSpeed response)-.11 E
(function w)100.8 345 Q(ould outweigh the unf)-.11 E(airness that w)-.11
E(ould be e)-.11 E(xperienced by Standard TCP in this)-.165 E(re)100.8
358 Q 2.75(gime. Ho)-.165 F(we)-.275 E -.165(ve)-.275 G .88 -.44(r, o)
.165 H
(ne purpose of this document is to solicit feedback on this issue.).44 E
(The)5.5 E(parameter Lo)100.8 371 Q(w_W)-.275 E(indo)-.44 E 2.75(wd)
-.275 G(etermines directly the point of di)-2.75 E -.165(ve)-.275 G
-.198(rg).165 G(ence between the Standard).198 E
(and HighSpeed Response Functions.)100.8 384 Q(The third column of T)
100.8 410 Q(able 5, the Aggre)-.88 E -.055(ga)-.165 G(te W).055 E(indo)
-.44 E 1.43 -.715(w, g)-.275 H -2.365 -.275(iv e).715 H 2.75(st).275 G
(he aggre)-2.75 E -.055(ga)-.165 G(te congestion).055 E(windo)100.8 423
Q 2.75(wo)-.275 G 2.75(ft)-2.75 G(he tw)-2.75 E 2.75(oc)-.11 G
(ompeting TCP connections, with HighSpeed and Standard TCP)-2.75 E 2.75
(,g)-1.221 G -2.365 -.275(iv e)-2.75 H(n).275 E(the pack)100.8 436 Q
(et drop rate speci\214ed in the \214rst column.)-.11 E(From T)5.5 E
(able 5, a HighSpeed TCP)-.88 E(connection w)100.8 449 Q(ould recei)-.11
E .33 -.165(ve t)-.275 H
(en times the bandwidth of a Standard TCP in an en).165 E(vironment)-.44
E(with a pack)100.8 462 Q(et drop rate of 10^-6.)-.11 E(This w)5.5 E
(ould occur when the tw)-.11 E 2.75<6f8d>-.11 G -.275(ow)-2.75 G 2.75
(ss).275 G(haring a single)-2.75 E(pipe achie)100.8 475 Q -.165(ve)-.275
G 2.75(da).165 G 2.75(na)-2.75 G(ggre)-2.75 E -.055(ga)-.165 G(te windo)
.055 E 2.75(wo)-.275 G 2.75(f1)-2.75 G(3479 pack)-2.75 E 2.75(ets. Gi)
-.11 F -.165(ve)-.275 G 2.75(nar).165 G(ound-trip time of 100 ms)-2.75 E
(and a pack)100.8 488 Q(et size of 1500 bytes, this w)-.11 E
(ould occur with an a)-.11 E -.275(va)-.22 G
(ilable bandwidth for the tw).275 E(o)-.11 E(competing \215o)100.8 501 Q
(ws of 1.6 Gbps.)-.275 E(Ne)100.8 527 Q
(xt we consider the time that it tak)-.165 E
(es a standard or HighSpeed TCP \215o)-.11 E 2.75(wt)-.275 G 2.75(oc)
-2.75 G(on)-2.75 E -.165(ve)-.44 G -.198(rg).165 G 2.75(et).198 G(o)
-2.75 E -.11(fa)100.8 540 S(irness ag).11 E(ainst a pre-e)-.055 E
(xisting HighSpeed TCP \215o)-.165 E 4.18 -.715(w. T)-.275 H(he w).715 E
(orst case for con)-.11 E -.165(ve)-.44 G -.198(rg).165 G(ence to).198 E
-.11(fa)100.8 553 S(irness occurs when a ne).11 E 2.75<778d>-.275 G .55
-.275(ow i)-2.75 H 2.75(ss).275 G(tarting up, competing ag)-2.75 E
(ainst a high-bandwidth)-.055 E -.165(ex)100.8 566 S(isting \215o).165 E
1.43 -.715(w, a)-.275 H(nd the ne).715 E 2.75<778d>-.275 G .55 -.275
(ow s)-2.75 H(uf).275 E(fers a pack)-.275 E(et drop and e)-.11 E
(xits slo)-.165 E(w-start while its windo)-.275 E(w)-.275 E
(is still small.)100.8 579 Q(In the w)5.5 E
(orst case, consider that the ne)-.11 E 2.75<778d>-.275 G .55 -.275
(ow h)-2.75 H(as entered the congestion).275 E -.22(avo)100.8 592 S
(idance phase while its windo).22 E 2.75(wi)-.275 G 2.75(so)-2.75 G
(nly one pack)-2.75 E 2.75(et. A)-.11 F(standard TCP \215o)2.75 E 2.75
(wi)-.275 G 2.75(nc)-2.75 G(ongestion)-2.75 E -.22(avo)100.8 605 S
(idance increases its windo).22 E 2.75(wb)-.275 G 2.75(ya)-2.75 G 2.75
(tm)-2.75 G(ost one pack)-2.75 E(et per round-trip time, and after N)
-.11 E(round-trip times has only achie)100.8 618 Q -.165(ve)-.275 G 2.75
(daw).165 G(indo)-2.75 E 2.75(wo)-.275 G 2.75(fNp)-2.75 G(ack)-2.75 E
(ets \(when starting with a windo)-.11 E 2.75(wo)-.275 G(f)-2.75 E 2.75
(1i)100.8 631 S 2.75(nt)-2.75 G(he \214rst round-trip time\).)-2.75 E
(In contrast, a HighSpeed TCP \215o)5.5 E(ws increases much f)-.275 E
(aster)-.11 E(than a standard TCP \215o)100.8 644 Q 2.75(ww)-.275 G
(hile in the congestion a)-2.75 E -.22(vo)-.22 G
(idance phase, and we can e).22 E(xpect its)-.165 E(con)100.8 657 Q
-.165(ve)-.44 G -.198(rg).165 G(ence to f).198 E
(airness to be much better)-.11 E 5.5(.T)-.605 G(his is sho)-5.5 E
(wn in T)-.275 E(able 6 belo)-.88 E 4.18 -.715(w. T)-.275 H
(he script used).715 E(to generate this table is gi)100.8 670 Q -.165
(ve)-.275 G 2.75(ni).165 G 2.75(nA)-2.75 G(ppendix C.)-2.75 E(Flo)72 769
Q 311.891(yd Section)-.11 F 2.75(6. [P)2.75 F(age 10])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E -.66(RT)106.3 85 S 5.5(TH).66
G(S_W)-5.5 E(indo)-.44 E 2.75(wS)-.275 G(tandard_TCP_W)-2.75 E(indo)-.44
E(w)-.275 E 2.75(--- ---------)106.3 98 R(-------------------)2.75 E
16.5(100 131)106.3 111 R(100)22 E 16.5(200 475)106.3 124 R(200)22 E
13.75(300 1131)106.3 137 R(300)22 E 13.75(400 2160)106.3 150 R(400)22 E
13.75(500 3601)106.3 163 R(500)22 E 13.75(600 5477)106.3 176 R(600)22 E
13.75(700 7799)106.3 189 R(700)22 E 11(800 10567)106.3 202 R(800)22 E 11
(900 13774)106.3 215 R(900)22 E 11(1000 17409)103.55 228 R(1000)19.25 E
11(1100 21455)103.55 241 R(1100)19.25 E 11(1200 25893)103.55 254 R(1200)
19.25 E 11(1300 30701)103.55 267 R(1300)19.25 E 11(1400 35856)103.55 280
R(1400)19.25 E 11(1500 41336)103.55 293 R(1500)19.25 E 11(1600 47115)
103.55 306 R(1600)19.25 E 11(1700 53170)103.55 319 R(1700)19.25 E 11
(1800 59477)103.55 332 R(1800)19.25 E 11(1900 66013)103.55 345 R(1900)
19.25 E 11(2000 72754)103.55 358 R(2000)19.25 E -.88(Ta)100.8 384 S
(ble 6:).88 E -.165(Fo)5.5 G 2.75(raH).165 G
(ighSpeed and a Standard TCP connection, the congestion windo)-2.75 E
2.75(wd)-.275 G(uring)-2.75 E(congestion a)100.8 397 Q -.22(vo)-.22 G
(idance phase \(starting with a congestion windo).22 E 2.75(wo)-.275 G
2.75(f1p)-2.75 G(ack)-2.75 E(et during R)-.11 E(TT 1.)-.66 E
(The classic paper on relati)100.8 423 Q .33 -.165(ve f)-.275 H
(airness is from Chiu and Jain [CJ89].).055 E(This paper sho)5.5 E
(ws that)-.275 E(AIMD \(Additi)100.8 436 Q .33 -.165(ve I)-.275 H
(ncrease Multiplicati).165 E .33 -.165(ve D)-.275 H(ecrease\) con).165 E
-.165(ve)-.44 G -.198(rg).165 G(es to f).198 E(airness in an en)-.11 E
(vironment)-.44 E(with synchronized congestion e)100.8 449 Q -.165(ve)
-.275 G 2.75(nts. From).165 F
([CJ89], it is easy to see that MIMD and AIAD)2.75 E(do not con)100.8
462 Q -.165(ve)-.44 G -.198(rg).165 G 2.75(et).198 G 2.75(of)-2.75 G
(airness in this en)-2.86 E 2.75(vironment. Ho)-.44 F(we)-.275 E -.165
(ve)-.275 G .88 -.44(r, t).165 H(he results of [CJ89] do not).44 E
(apply to an asynchronous en)100.8 475 Q
(vironment such as that of the current Internet, where the)-.44 E
(frequenc)100.8 488 Q 2.75(yo)-.165 G 2.75(fc)-2.75 G
(ongestion feedback can be dif)-2.75 E(ferent for dif)-.275 E
(ferent \215o)-.275 E 2.75(ws. F)-.275 F(or e)-.165 E(xample, it has)
-.165 E(been sho)100.8 501 Q(wn that MIMD con)-.275 E -.165(ve)-.44 G
-.198(rg).165 G(es to f).198 E
(air states in a model with proportional instead of)-.11 E
(synchronous feedback in terms of pack)100.8 514 Q(et drops [GV02].)-.11
E(Thus, we are not concerned about)5.5 E
(abandoning a strict model of AIMD for HighSpeed TCP)100.8 527 Q(.)
-1.221 E/F1 11/Times-Bold@0 SF(7.)72 566 Q/F2 14/Times-Bold@0 SF -1.036
(Tr)5.5 G(anslating the HighSpeed Response Function into Congestion)
1.036 E(Contr)72 579 Q(ol P)-.252 E(arameters.)-.14 E F0 -.165(Fo)100.8
605 S 2.75(re).165 G(quation-based congestion control such as TFRC, the\
 HighSpeed Response Function)-2.75 E(abo)100.8 618 Q .33 -.165(ve c)
-.165 H(ould be used directly by the TFRC congestion control mechanism.)
.165 E(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44(r, f).165 H(or).44
E(TCP the HighSpeed response function has to be translated into additi)
100.8 631 Q .33 -.165(ve i)-.275 H(ncrease and).165 E(multiplicati)100.8
644 Q .33 -.165(ve d)-.275 H(ecrease parameters.).165 E
(The HighSpeed response function cannot be achie)5.5 E -.165(ve)-.275 G
(d).165 E(by TCP with an additi)100.8 657 Q .33 -.165(ve i)-.275 H
(ncrease of one se).165 E(gment per round-trip time and a multiplicati)
-.165 E -.165(ve)-.275 G
(decrease of halving the current congestion windo)100.8 670 Q
(w; HighSpeed TCP will ha)-.275 E .33 -.165(ve t)-.22 H 2.75(om).165 G
(odify)-2.75 E(either the increase or the decrease parameter)100.8 683 Q
2.75(,o)-.44 G 2.75(rb)-2.75 G 2.75(oth. W)-2.75 F 2.75(eh)-.88 G -2.475
-.22(av e)-2.75 H(concluded that HighSpeed)2.97 E(TCP is most lik)100.8
696 Q(ely to achie)-.11 E .33 -.165(ve a)-.275 H 2.75(na).165 G
(cceptable compromise between moderate increases and)-2.75 E(timely dec\
reases by modifying both the increase and the decrease parameter)100.8
709 Q(.)-.605 E(Flo)72 769 Q 311.891(yd Section)-.11 F 2.75(7. [P)2.75 F
(age 11])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E
(That is, for HighSpeed TCP let the congestion windo)100.8 85 Q 2.75(wi)
-.275 G(ncrease by a\(w\) se)-2.75 E(gments per)-.165 E(round-trip time\
 in the absence of congestion, and let the congestion windo)100.8 98 Q
2.75(wd)-.275 G(ecrease to)-2.75 E(w\(1-b\(w\)\) se)100.8 111 Q
(gments in response to a round-trip time with one or more loss e)-.165 E
-.165(ve)-.275 G 2.75(nts. Thus,).165 F(in)2.75 E
(response to a single ackno)100.8 124 Q
(wledgement HighSpeed TCP increases its congestion windo)-.275 E 2.75
(wi)-.275 G(n)-2.75 E(se)100.8 137 Q(gments as follo)-.165 E(ws:)-.275 E
2.75(w<)103.55 163 S 2.75(-w+a)-2.75 G(\(w\)/w)-2.75 E(.)-.715 E
(In response to a congestion e)100.8 189 Q -.165(ve)-.275 G
(nt, HighSpeed TCP decreases as follo).165 E(ws:)-.275 E 2.75(w<)103.55
215 S 2.75(-\()-2.75 G(1-b\(w\)\)w)-2.75 E(.)-.715 E -.165(Fo)100.8 241
S 2.75(rS).165 G(tandard TCP)-2.75 E 2.75(,a)-1.221 G
(\(w\) = 1 and b\(w\) = 1/2, re)-2.75 E -.055(ga)-.165 G
(rdless of the v).055 E(alue of w)-.275 E 5.5(.H)-.715 G(ighSpeed TCP)
-5.5 E(uses the same v)100.8 254 Q
(alues of a\(w\) and b\(w\) for w <= Lo)-.275 E(w_W)-.275 E(indo)-.44 E
4.18 -.715(w. T)-.275 H(his section speci\214es a\(w\)).715 E
(and b\(w\) for HighSpeed TCP for lar)100.8 267 Q(ger v)-.198 E
(alues of w)-.275 E(.)-.715 E -.165(Fo)100.8 293 S 2.75(rw=H).165 G
(igh_W)-2.75 E(indo)-.44 E 1.43 -.715(w, w)-.275 H 2.75(eh).715 G -2.475
-.22(av e)-2.75 H(speci\214ed a loss rate of High_P)2.97 E 5.5(.F)-1.221
G(rom [FRS02], or from)-5.5 E
(elementary calculations, this requires the follo)100.8 306 Q
(wing relationship between a\(w\) and b\(w\) for)-.275 E 2.75(w=H)100.8
319 S(igh_W)-2.75 E(indo)-.44 E(w:)-.275 E(a\(w\) = High_W)103.55 345 Q
(indo)-.44 E(w^2 * High_P * 2 * b\(w\)/\(2-b\(w\).)-.275 E(\(2\))13.75 E
1.76 -.88(We u)100.8 371 T(se the parameter High_Decrease to specify th\
e decrease parameter b\(w\) for w =).88 E(High_W)100.8 384 Q(indo)-.44 E
1.43 -.715(w, a)-.275 H(nd use Equation \(2\) to deri).715 E .33 -.165
(ve t)-.275 H(he increase parameter a\(w\) for w =).165 E(High_W)100.8
397 Q(indo)-.44 E 4.18 -.715(w. A)-.275 H
(long with High_P = 10^-7 and High_W).715 E(indo)-.44 E 2.75(w=8)-.275 G
(3000, for e)-2.75 E(xample, we)-.165 E
(specify High_Decrease = 0.1, specifying that b\(83000\) = 0.1, gi)100.8
410 Q(ving a decrease of 10%)-.275 E(after a congestion e)100.8 423 Q
-.165(ve)-.275 G 2.75(nt. Equation).165 F(\(2\) then gi)2.75 E -.165(ve)
-.275 G 2.75(sa).165 G(\(83000\) = 72, for an increase of 72)-2.75 E(se)
100.8 436 Q
(gments, or just under 0.1%, within a round-trip time, for w = 83000.)
-.165 E(This moderate decrease strik)100.8 462 Q
(es us as acceptable, particularly when coupled with the role of)-.11 E
(TCP')100.8 475 Q 2.75(sA)-.605 G
(CK-clocking in limiting the sending rate in response to more se)-3.19 E
-.165(ve)-.275 G(re congestion).165 E 2.75([BBFS01]. A)100.8 488 R
(more se)2.75 E -.165(ve)-.275 G(re decrease w).165 E
(ould require a more aggressi)-.11 E .33 -.165(ve i)-.275 H
(ncrease in the).165 E(congestion windo)100.8 501 Q 2.75(wf)-.275 G
(or a round-trip time without congestion.)-2.75 E(In particular)5.5 E
2.75(,ad)-.44 G(ecrease)-2.75 E -.11(fa)100.8 514 S
(ctor High_Decrease of 0.5, as in Standard TCP).11 E 2.75(,w)-1.221 G
(ould require an increase of 459)-2.86 E(se)100.8 527 Q
(gments per round-trip time when w = 83000.)-.165 E(Gi)100.8 553 Q -.165
(ve)-.275 G 2.75(nd).165 G
(ecrease parameters of b\(w\) = 1/2 for w = Lo)-2.75 E(w_W)-.275 E(indo)
-.44 E 1.43 -.715(w, a)-.275 H(nd b\(w\) =).715 E
(High_Decrease for w = High_W)100.8 566 Q(indo)-.44 E 1.43 -.715(w, w)
-.275 H 2.75(ea).715 G(re left to specify the v)-2.75 E
(alue of b\(w\) for other)-.275 E -.275(va)100.8 579 S(lues of w > Lo)
.275 E(w_W)-.275 E(indo)-.44 E 4.18 -.715(w. F)-.275 H
(rom [FRS02], we let b\(w\) v).715 E(ary linearly as the log of w)-.275
E 2.75(,a)-.715 G(s)-2.75 E(follo)100.8 592 Q(ws:)-.275 E(b\(w\) = \(Hi\
gh_Decrease - 0.5\) \(log\(w\)-log\(W\)\) / \(log\(W_1\)-log\(W\)\) + 0\
.5,)103.55 618 Q(for W = Lo)100.8 644 Q(w_windo)-.275 E 2.75(wa)-.275 G
(nd W_1 = High_windo)-2.75 E 4.18 -.715(w. T)-.275 H
(he increase parameter a\(w\) can then be).715 E(computed as follo)100.8
657 Q(ws:)-.275 E(a\(w\) = w^2 * p\(w\) * 2 * b\(w\)/\(2-b\(w\)\),)
103.55 683 Q(for p\(w\) the pack)100.8 709 Q
(et drop rate for congestion windo)-.11 E 2.75(ww)-.275 G 5.5(.F)-3.465
G(rom in)-5.5 E -.165(ve)-.44 G(rting Equation \(1\), we).165 E
(get p\(w\) as follo)100.8 722 Q(ws:)-.275 E(Flo)72 769 Q 311.891
(yd Section)-.11 F 2.75(7. [P)2.75 F(age 12])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E(p\(w\) = 0.078/w^1.2.)103.55
85 Q 1.76 -.88(We a)100.8 111 T(ssume that e).88 E
(xperimental implementations of HighSpeed TCP for further in)-.165 E
-.165(ve)-.44 G(stig).165 E(ation)-.055 E
(will use a pre-computed look-up table for \214nding a\(w\) and b\(w\).)
100.8 124 Q -.165(Fo)5.5 G 2.75(re).165 G(xample, the)-2.915 E
(implementation from T)100.8 137 Q(om Dunig)-.88 E
(an adjusts the a\(w\) and b\(w\) parameters e)-.055 E -.165(ve)-.275 G
(ry 0.1).165 E 2.75(seconds. In)100.8 150 R(the appendix we gi)2.75 E
.33 -.165(ve s)-.275 H(uch a table for our def).165 E(ault v)-.11 E
(alues of Lo)-.275 E(w_W)-.275 E(indo)-.44 E 2.75(w=3)-.275 G(8,)-2.75 E
(High_W)100.8 163 Q(indo)-.44 E 2.75(w=8)-.275 G
(3,000, High_P = 10^-7, and High_Decrease = 0.1.)-2.75 E
(These are also the)5.5 E(def)100.8 176 Q(ault v)-.11 E
(alues in the NS simulator; e)-.275 E
(xample simulations in NS can be run with the)-.165 E
(command "./test-all-tcpHighspeed" in the directory tcl/test.)100.8 189
Q/F1 11/Times-Bold@0 SF(8.)72 228 Q/F2 14/Times-Bold@0 SF(An alter)5.5 E
(nate, linear r)-.21 E(esponse functions.)-.252 E F0
(In this section we e)100.8 254 Q
(xplore an alternate, linear response function for HighSpeed TCP that)
-.165 E(has been proposed by a number of other people, in particular by\
 Glenn V)100.8 267 Q(innicombe and)-.66 E -.88(To)100.8 280 S 2.75(mK)
.88 G(elly)-3.025 E 5.5(.S)-.715 G(imilarly)-5.5 E 2.75(,i)-.715 G 2.75
(th)-2.75 G
(as been suggested by others that a less "ad-hoc" guideline for a)-2.75
E(response function for HighSpeed TCP w)100.8 293 Q
(ould be to specify a constant v)-.11 E(alue for the number)-.275 E
(of round-trip times between congestion e)100.8 306 Q -.165(ve)-.275 G
(nts.).165 E(Assume that we k)100.8 332 Q(eep the v)-.11 E(alue of Lo)
-.275 E(w_W)-.275 E(indo)-.44 E 2.75(wa)-.275 G 2.75(s3)-2.75 G 2.75(8M)
-2.75 G(SS-sized se)-2.75 E(gments, indicating)-.165 E
(when the HighSpeed response function di)100.8 345 Q -.165(ve)-.275 G
-.198(rg).165 G(es from the current TCP response function,).198 E -.22
(bu)100.8 358 S 2.75(tt).22 G(hat we modify the High_W)-2.75 E(indo)-.44
E 2.75(wa)-.275 G(nd High_P parameters that specify the upper range)
-2.75 E(of the HighSpeed response function.)100.8 371 Q(In particular)
5.5 E 2.75(,c)-.44 G(onsider the response function gi)-2.75 E -.165(ve)
-.275 G 2.75(nb).165 G(y)-2.75 E(High_W)100.8 384 Q(indo)-.44 E 2.75
(w=3)-.275 G(80,000 and High_P = 10^-7, with Lo)-2.75 E(w_W)-.275 E
(indo)-.44 E 2.75(w=3)-.275 G 2.75(8a)-2.75 G(nd Lo)-2.75 E(w_P =)-.275
E(10^-3 as before.)100.8 397 Q(Using the equations in Section 5, this w)
100.8 423 Q(ould gi)-.11 E .33 -.165(ve t)-.275 H(he follo).165 E
(wing Linear response function,)-.275 E(for w > Lo)100.8 436 Q(w_W)-.275
E(indo)-.44 E(w:)-.275 E 2.75(W=0)106.3 462 S(.038/p.)-2.75 E
(This Linear HighSpeed response function is illustrated in T)100.8 488 Q
(able 7 belo)-.88 E 4.18 -.715(w. F)-.275 H(or HighSpeed).55 E(TCP)100.8
501 Q 2.75(,t)-1.221 G(he number of round-trip times between losses, 1/\
\(pW\), equals 1/0.38, or)-2.75 E(equi)100.8 514 Q -.275(va)-.275 G
(lently).275 E 2.75(,2)-.715 G(6, for W > 38 se)-2.75 E(gments.)-.165 E
(Flo)72 769 Q 311.891(yd Section)-.11 F 2.75(8. [P)2.75 F(age 13])-.165
E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E -.165(Pa)111.8 85 S(ck).165 E
(et Drop Rate P)-.11 E(Congestion W)8.25 E(indo)-.44 E 2.75 2.75(wW R)
-.275 H(TTs Between Losses)-3.41 E 5.5
(------------------ -------------------)111.8 98 R(-------------------)
11 E 52.25(10^-2 12)131.05 111 R(8)52.25 E 52.25(10^-3 38)131.05 124 R
(26)49.5 E 49.5(10^-4 380)131.05 137 R(26)58.674 E 46.75(10^-5 3800 26)
131.05 150 R 44(10^-6 38000)131.05 163 R(26)49.5 E 41.25(10^-7 380000)
131.05 176 R(26)49.5 E 38.5(10^-8 3800000)131.05 189 R(26)49.5 E 35.75
(10^-9 38000000)131.05 202 R(26)49.5 E 30.25(10^-10 380000000)131.05 215
R(26)49.5 E -.88(Ta)100.8 241 S
(ble 7: An Alternate, Linear TCP Response Function for HighSpeed TCP).88
E 5.5(.T)-1.221 G(he a)-5.5 E -.165(ve)-.22 G(rage).165 E
(congestion windo)100.8 254 Q 2.75(wWi)-.275 G 2.75(nM)-2.75 G
(SS-sized se)-2.75 E(gments is gi)-.165 E -.165(ve)-.275 G 2.75(na).165
G 2.75(saf)-2.75 G(unction of the pack)-2.75 E(et drop rate)-.11 E
-1.221(P.)100.8 267 S(Gi)100.8 293 Q -.165(ve)-.275 G 2.75(nac).165 G
(onstant decrease b\(w\) of 1/2, this w)-2.75 E(ould gi)-.11 E .33 -.165
(ve a)-.275 H 2.75(ni).165 G(ncrease a\(w\) of)-2.75 E(w/Lo)100.8 306 Q
(w_W)-.275 E(indo)-.44 E 1.43 -.715(w, o)-.275 H 2.75(re).715 G(qui)
-2.75 E -.275(va)-.275 G(lently).275 E 2.75(,ac)-.715 G
(onstant increase of 1/Lo)-2.75 E(w_W)-.275 E(indo)-.44 E 2.75(wp)-.275
G(ack)-2.75 E(ets per)-.11 E(ackno)100.8 319 Q(wledgement, for w > Lo)
-.275 E(w_W)-.275 E(indo)-.44 E 4.18 -.715(w. A)-.275 H
(nother possibility is Scalable TCP [K03],).715 E(which uses a \214x)
100.8 332 Q(ed decrease b\(w\) of 1/8 and a \214x)-.165 E
(ed increase per ackno)-.165 E(wledgement of 0.01.)-.275 E(This gi)100.8
345 Q -.165(ve)-.275 G 2.75(sa).165 G 2.75(ni)-2.75 G
(ncrease a\(w\) per windo)-2.75 E 2.75(wo)-.275 G 2.75(f0)-2.75 G
(.005 w)-2.75 E 2.75(,f)-.715 G(or a TCP with delayed)-2.75 E(ackno)
100.8 358 Q(wledgements, for pure MIMD.)-.275 E(The relati)100.8 384 Q
.33 -.165(ve f)-.275 H(airness between the alternate Linear response fu\
nction and the standard TCP).055 E
(response function is illustrated belo)100.8 397 Q 2.75(wi)-.275 G 2.75
(nT)-2.75 G(able 8.)-3.63 E -.165(Pa)106.3 423 S(ck).165 E
(et Drop Rate P)-.11 E -.165(Fa)8.25 G 2.75(irness Aggre).165 F -.055
(ga)-.165 G(te W).055 E(indo)-.44 E 5.5(wB)-.275 G(andwidth)-5.5 E 5.5
(------------------ --------)106.3 436 R 2.75
(---------------- ---------)5.5 F 30.25(10^-2 1.0)125.55 449 R 19.25
(24 2.8)38.5 F(Mbps)2.75 E 30.25(10^-3 1.0)125.55 462 R 19.25(76 9.1)
38.5 F(Mbps)2.75 E 30.25(10^-4 3.2)125.55 475 R 16.5(500 60.0)35.75 F
(Mbps)2.75 E 27.5(10^-5 15.1)125.55 488 R 13.75(4179 501.4)33 F(Mbps)
2.75 E 27.5(10^-6 31.6 39200)125.55 501 R(4.7 Gbps)22 E 24.75
(10^-7 100.1 383795)125.55 514 R(46.0 Gbps)19.25 E -.88(Ta)100.8 540 S
(ble 8: Relati).88 E .33 -.165(ve Fa)-.275 H
(irness between the Linear HighSpeed and Standard Response).165 E
(Functions.)100.8 553 Q
(One attraction of the linear response function is that it is scale-in)
100.8 592 Q -.275(va)-.44 G(riant, with a \214x).275 E(ed)-.165 E
(increase in the congestion windo)100.8 605 Q 2.75(wp)-.275 G(er ackno)
-2.75 E(wledgement, and a \214x)-.275 E(ed number of round-trip)-.165 E
(times between loss e)100.8 618 Q -.165(ve)-.275 G 2.75(nts. My).165 F
-.275(ow)2.75 G 2.75(na).275 G(ssumption w)-2.75 E(ould be that ha)-.11
E(ving a \214x)-.22 E(ed length for the)-.165 E
(congestion epoch in round-trip times, re)100.8 631 Q -.055(ga)-.165 G
(rdless of the pack).055 E(et drop rate, w)-.11 E(ould be a poor \214t)
-.11 E(for an imprecise and imperfect w)100.8 644 Q
(orld with routers with a range of queue management)-.11 E
(mechanisms, such as the Drop-T)100.8 657 Q
(ail queue management that is common today)-.88 E 5.5(.F)-.715 G(or)
-5.665 E -.165(ex)100.8 670 S(ample, a response function with a \214x)
.165 E(ed length for the congestion epoch in round-trip)-.165 E
(times might gi)100.8 683 Q .33 -.165(ve l)-.275 H(ess clearly-dif).165
E(ferentiated feedback in an en)-.275 E(vironment with steady-state)-.44
E(background losses at \214x)100.8 696 Q(ed interv)-.165 E
(als for all \215o)-.275 E
(ws \(as might occur with a wireless link with)-.275 E
(occasional short error b)100.8 709 Q(ursts, gi)-.22 E
(ving losses for all \215o)-.275 E(ws e)-.275 E -.165(ve)-.275 G
(ry N seconds re).165 E -.055(ga)-.165 G(rdless of their).055 E
(sending rate\).)100.8 722 Q(Flo)72 769 Q 311.891(yd Section)-.11 F 2.75
(8. [P)2.75 F(age 14])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E(While it is not a goal to ha)
100.8 85 Q .33 -.165(ve p)-.22 H(erfect f).165 E(airness in an en)-.11 E
(vironment with synchronized losses,)-.44 E(it w)100.8 98 Q
(ould be good to ha)-.11 E .33 -.165(ve m)-.22 H
(oderately acceptable performance in this re).165 E 2.75(gime. This)
-.165 F(goal)2.75 E(might ar)100.8 111 Q(gue ag)-.198 E
(ainst a response function with a constant number of round-trip times)
-.055 E(between congestion e)100.8 124 Q -.165(ve)-.275 G 2.75(nts. Ho)
.165 F(we)-.275 E -.165(ve)-.275 G .88 -.44(r, t).165 H
(his is a question that could clearly use additional).44 E
(research and in)100.8 137 Q -.165(ve)-.44 G(stig).165 E 2.75(ation. In)
-.055 F(addition, \215o)2.75 E(ws with dif)-.275 E
(ferent round-trip times w)-.275 E(ould ha)-.11 E -.165(ve)-.22 G(dif)
100.8 150 Q(ferent time durations for congestion epochs e)-.275 E -.165
(ve)-.275 G 2.75(ni).165 G 2.75(nt)-2.75 G
(he model with a linear response)-2.75 E(function.)100.8 163 Q
(The third column of T)100.8 189 Q(able 8, the Aggre)-.88 E -.055(ga)
-.165 G(te W).055 E(indo)-.44 E 1.43 -.715(w, g)-.275 H -2.365 -.275
(iv e).715 H 2.75(st).275 G(he aggre)-2.75 E -.055(ga)-.165 G
(te congestion).055 E(windo)100.8 202 Q 2.75(wo)-.275 G 2.75(ft)-2.75 G
.22 -.11(wo c)-2.75 H
(ompeting TCP connections, one with Linear HighSpeed TCP and one with)
.11 E(Standard TCP)100.8 215 Q 2.75(,g)-1.221 G -2.365 -.275(iv e)-2.75
H 2.75(nt).275 G(he pack)-2.75 E
(et drop rate speci\214ed in the \214rst column.)-.11 E(From T)5.5 E
(able 8, a)-.88 E(Linear HighSpeed TCP connection w)100.8 228 Q
(ould recei)-.11 E .33 -.165(ve \214)-.275 H
(fteen times the bandwidth of a Standard).165 E(TCP in an en)100.8 241 Q
(vironment with a pack)-.44 E(et drop rate of 10^-5.)-.11 E(This w)5.5 E
(ould occur when the tw)-.11 E(o)-.11 E<8d6f>100.8 254 Q
(ws sharing a single pipe achie)-.275 E -.165(ve)-.275 G 2.75(da).165 G
2.75(na)-2.75 G(ggre)-2.75 E -.055(ga)-.165 G(te windo).055 E 2.75(wo)
-.275 G 2.75(f4)-2.75 G(179 pack)-2.75 E 2.75(ets. Gi)-.11 F -.165(ve)
-.275 G 2.75(nar).165 G(ound-)-2.75 E(trip time of 100 ms and a pack)
100.8 267 Q(et size of 1500 bytes, this w)-.11 E(ould occur with an a)
-.11 E -.275(va)-.22 G(ilable).275 E(bandwidth for the tw)100.8 280 Q
2.75(oc)-.11 G(ompeting \215o)-2.75 E(ws of 501 Mbps.)-.275 E
(Thus, because the Linear HighSpeed)5.5 E(TCP is more aggressi)100.8 293
Q .33 -.165(ve t)-.275 H(han the HighSpeed TCP proposed abo).165 E -.165
(ve)-.165 G 2.75(,i).165 G 2.75(ta)-2.75 G(lso is less f)-2.75 E
(air when)-.11 E(competing with Standard TCP in a high-bandwidth en)
100.8 306 Q(vironment.)-.44 E/F1 11/Times-Bold@0 SF(9.)72 345 Q/F2 14
/Times-Bold@0 SF -1.036(Tr)5.5 G(adeoffs f)1.036 E
(or Choosing Congestion Contr)-.35 E(ol P)-.252 E(arameters.)-.14 E F0
2.75(Ar)100.8 371 S(ange of metrics can be used for e)-2.75 E -.275(va)
-.275 G(luating choices for congestion control parameters for).275 E
(HighSpeed TCP)100.8 384 Q 5.5(.M)-1.221 G 2.75(ya)-5.5 G
(ssumption in this section is that for a response function of the form)
-2.75 E 2.75(w=c)100.8 397 S(/p^d, for constant c and e)-2.75 E
(xponent d, the only response functions that w)-.165 E(ould be)-.11 E
(considered are response functions with 1/2 <= d <= 1.)100.8 410 Q
(The tw)5.5 E 2.75(oe)-.11 G(nds of this spectrum are)-2.75 E
(represented by current TCP)100.8 423 Q 2.75(,w)-1.221 G
(ith d = 1/2, and by the linear response function described in)-2.75 E
(Section 8 abo)100.8 436 Q -.165(ve)-.165 G 2.75(,w).165 G(ith d = 1.)
-2.75 E(HighSpeed TCP lies some)5.5 E(where in the middle of the)-.275 E
(spectrum, with d = 0.835.)100.8 449 Q(Response functions with e)100.8
475 Q(xponents less than 1/2 can be eliminated from consideration)-.165
E(because the)100.8 488 Q 2.75(yw)-.165 G(ould be e)-2.86 E -.165(ve)
-.275 G 2.75(nw).165 G
(orse than standard TCP in accomodating connections with)-2.86 E
(high congestion windo)100.8 501 Q(ws.)-.275 E F1(9.1.)72 540 Q/F3 13
/Times-Bold@0 SF(The Number of Round-T)5.5 E(rip T)-.962 E
(imes between Loss Ev)-.234 E(ents.)-.13 E F0(Response functions with e)
100.8 566 Q
(xponents greater than 1 can be eliminated from consideration)-.165 E(b\
ecause for these response functions, the number of round-trip times bet\
ween loss e)100.8 579 Q -.165(ve)-.275 G(nts).165 E
(decreases as congestion decreases.)100.8 592 Q -.165(Fo)5.5 G 2.75(rar)
.165 G(esponse function of w = c/p^d, with one loss)-2.75 E -2.365 -.275
(ev e)100.8 605 T(nt or congestion e).275 E -.165(ve)-.275 G(nt e).165 E
-.165(ve)-.275 G(ry 1/p pack).165 E
(ets, the number of round-trip times between loss)-.11 E -2.365 -.275
(ev e)100.8 618 T(nts is w^\(\(1/d\)-1\)/c^\(1/d\).).275 E
(Thus, for standard TCP the number of round-trip times)5.5 E
(between loss e)100.8 631 Q -.165(ve)-.275 G(nts is linear in w).165 E
5.5(.I)-.715 G 2.75(nc)-5.5 G
(ontrast, one attraction of the linear response)-2.75 E
(function, as described in Section 8 abo)100.8 644 Q -.165(ve)-.165 G
2.75(,i).165 G 2.75(st)-2.75 G(hat it is scale-in)-2.75 E -.275(va)-.44
G(riant, in terms of a \214x).275 E(ed)-.165 E
(increase in the congestion windo)100.8 657 Q 2.75(wp)-.275 G(er ackno)
-2.75 E(wledgement, and a \214x)-.275 E(ed number of round-trip)-.165 E
(times between loss e)100.8 670 Q -.165(ve)-.275 G(nts.).165 E(Ho)100.8
696 Q(we)-.275 E -.165(ve)-.275 G .88 -.44(r, f).165 H(or a response fu\
nction with d > 1, the number of round-trip times between loss).44 E
-2.365 -.275(ev e)100.8 709 T(nts w).275 E
(ould be proportional to w^\(\(1/d\)-1\), for a ne)-.11 E -.055(ga)-.165
G(ti).055 E .33 -.165(ve ex)-.275 H(ponent \(\(1/d\)-1\), setting).165 E
(smaller as w increases.)100.8 722 Q(This w)5.5 E
(ould seem undesirable.)-.11 E(Flo)72 769 Q 303.641(yd Section)-.11 F
2.75(9.1. [P)2.75 F(age 15])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E/F1 11/Times-Bold@0 SF(9.2.)72
85 Q/F2 13/Times-Bold@0 SF(The Number of P)5.5 E(ack)-.13 E(et Dr)-.13 E
(ops per Loss Ev)-.234 E(ent, with Dr)-.13 E(op-T)-.234 E(ail.)-1.196 E
F0 2.75(AT)100.8 111 S
(CP connection increases its sending rate by a\(w\) pack)-2.75 E
(ets per round-trip time, and in a)-.11 E(Drop-T)100.8 124 Q(ail en)-.88
E(vironment, this is lik)-.44 E(ely to result in a\(w\) dropped pack)
-.11 E(ets during a single loss)-.11 E -2.365 -.275(ev e)100.8 137 T
2.75(nt. One).275 F(attraction of standard TCP is that it has a \214x)
2.75 E(ed increase per round-trip time of)-.165 E(one pack)100.8 150 Q
(et, minimizing the number of pack)-.11 E(ets that w)-.11 E
(ould be dropped in a Drop-T)-.11 E(ail)-.88 E(en)100.8 163 Q 2.75
(vironment. F)-.44 F(or an en)-.165 E(vironment with some form of Acti)
-.44 E .33 -.165(ve Q)-.275 H(ueue Management, and in).165 E
(particular for an en)100.8 176 Q
(vironment that uses ECN, the number of pack)-.44 E
(ets dropped in a single)-.11 E(congestion e)100.8 189 Q -.165(ve)-.275
G(nt w).165 E(ould not be a problem.)-.11 E(Ho)5.5 E(we)-.275 E -.165
(ve)-.275 G .88 -.44(r, e).165 H -.165(ve).165 G 2.75(ni).165 G 2.75(nt)
-2.75 G(hese en)-2.75 E(vironments, lar)-.44 E(ger)-.198 E
(increases in the sending rate per round-trip time result in lar)100.8
202 Q(ger stresses on the ability of the)-.198 E
(queues in the router to absorb the \215uctuations.)100.8 215 Q(HighSpe\
ed TCP plays a middle ground between the metrics of a moderate number o\
f)100.8 241 Q(round-trip times between loss e)100.8 254 Q -.165(ve)-.275
G(nts, and a moderate increase in the sending rate per).165 E
(round-trip time.)100.8 267 Q(As sho)5.5 E
(wn in Appendix B, for a congestion windo)-.275 E 2.75(wo)-.275 G 2.75
(f8)-2.75 G(3,000 pack)-2.75 E(ets,)-.11 E
(HighSpeed TCP increases its sending rate by 70 pack)100.8 280 Q
(ets per round-trip time, resulting in at)-.11 E(most 70 pack)100.8 293
Q(et drops when the b)-.11 E(uf)-.22 E(fer o)-.275 E -.165(ve)-.165 G
(r\215o).165 E(ws in a Drop-T)-.275 E(ail en)-.88 E 2.75
(vironment. This)-.44 F(increased aggressi)100.8 306 Q -.165(ve)-.275 G
(ness is the price paid by HighSpeed TCP for its increased scalability)
.165 E(.)-.715 E 2.75(Al)100.8 319 S(ar)-2.75 E(ge number of pack)-.198
E(ets dropped per congestion e)-.11 E -.165(ve)-.275 G
(nt could result in synchronized drops).165 E(from multiple \215o)100.8
332 Q(ws, with a possible loss of throughput as a result.)-.275 E
(Scalable TCP has an increase a\(w\) of 0.005 w pack)100.8 358 Q
(ets per round-trip time.)-.11 E -.165(Fo)5.5 G 2.75(ra).165 G
(congestion windo)100.8 371 Q 2.75(wo)-.275 G 2.75(f8)-2.75 G
(3,000 pack)-2.75 E(ets, this gi)-.11 E -.165(ve)-.275 G 2.75(sa).165 G
2.75(ni)-2.75 G(ncrease of 415 pack)-2.75 E(ets per round-trip)-.11 E
(time, resulting in roughly 415 pack)100.8 384 Q
(et drops per congestion e)-.11 E -.165(ve)-.275 G(nt in a Drop-T).165 E
(ail)-.88 E(en)100.8 397 Q(vironment.)-.44 E
(Thus, HighSpeed TCP and its v)100.8 423 Q
(ariants place increased demands on queue management in)-.275 E
(routers, relati)100.8 436 Q .33 -.165(ve t)-.275 H 2.75(oS).165 G
(tandard TCP)-2.75 E 5.5(.\()-1.221 G
(This is rather similar to the increased demands on queue)-5.5 E
(management that w)100.8 449 Q
(ould result from using N parallel TCP connections instead of a single)
-.11 E(Standard TCP connection.\))100.8 462 Q F1(10.)72 501 Q/F3 14
/Times-Bold@0 SF(Related Issues)5.5 E F1(10.1.)72 540 Q F2(Slo)5.5 E
(w-Start.)-.13 E F0(An companion internet-draft on "Limited Slo)100.8
566 Q(w-Start for TCP with Lar)-.275 E(ge Congestion)-.198 E -.44(Wi)
100.8 579 S(ndo).44 E(ws" [F02b] proposes a modi\214cation to TCP')-.275
E 2.75(ss)-.605 G(lo)-2.75 E(w-start procedure that can)-.275 E
(signi\214cantly impro)100.8 592 Q .33 -.165(ve t)-.165 H
(he performance of TCP connections slo).165 E(w-starting up to lar)-.275
E(ge)-.198 E(congestion windo)100.8 605 Q 2.75(ws. F)-.275 F
(or TCP connections that are able to use congestion windo)-.165 E(ws of)
-.275 E(thousands \(or tens of thousands\) of MSS-sized se)100.8 618 Q
(gments \(for MSS the sender')-.165 E(s)-.605 E
(MAXIMUM SEGMENT SIZE\), the current slo)100.8 631 Q
(w-start procedure can result in increasing)-.275 E
(the congestion windo)100.8 644 Q 2.75(wb)-.275 G 2.75(yt)-2.75 G
(housands of se)-2.75 E(gments in a single round-trip time.)-.165 E
(Such an)5.5 E(increase can easily result in thousands of pack)100.8 657
Q(ets being dropped in one round-trip time.)-.11 E
(This is often counter)100.8 670 Q(-producti)-.22 E .33 -.165(ve f)-.275
H(or the TCP \215o).165 E 2.75(wi)-.275 G
(tself, and is also hard on the rest of the)-2.75 E(traf)100.8 683 Q
(\214c sharing the congested link.)-.275 E([F02b] proposes Limited Slo)
100.8 709 Q(w-Start, limiting the number of se)-.275 E
(gments by which the)-.165 E(congestion windo)100.8 722 Q 2.75(wi)-.275
G 2.75(si)-2.75 G(ncreased for one windo)-2.75 E 2.75(wo)-.275 G 2.75
(fd)-2.75 G(ata during slo)-2.75 E(w-start, in order to)-.275 E(Flo)72
769 Q 298.141(yd Section)-.11 F 2.75(10.1. [P)2.75 F(age 16])-.165 E 0
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(December 2003)2.75 E(June 2003)116.406 E(impro)100.8 85 Q .33 -.165
(ve p)-.165 H(erformance for TCP connections with lar).165 E
(ge congestion windo)-.198 E 2.75(ws. W)-.275 F 2.75(eh)-.88 G -2.475
-.22(av e)-2.75 H(separated out Limited Slo)100.8 98 Q
(w-Start to a separate draft because it can be used both with)-.275 E
(Standard or with HighSpeed TCP)100.8 111 Q(.)-1.221 E(Limited Slo)100.8
137 Q(w-Start is illustrated in the NS simulator)-.275 E 2.75(,f)-.44 G
(or snapshots after May 1, 2002, in)-2.75 E(the tests "./test-all-tcpHi\
ghspeed tcp1A" and "./test-all-tcpHighspeed tcpHighspeed1" in)100.8 150
Q(the subdirectory "tcl/lib".)100.8 163 Q(In order for best-ef)100.8 189
Q(fort \215o)-.275 E(ws to safely start-up f)-.275 E(aster than slo)-.11
E(w-start, e.g., in future high-)-.275 E(bandwidth netw)100.8 202 Q
(orks, we belie)-.11 E .33 -.165(ve t)-.275 H(hat it w).165 E
(ould be necessary for the \215o)-.11 E 2.75(wt)-.275 G 2.75(oh)-2.75 G
-2.475 -.22(av e)-2.75 H -.165(ex)2.97 G(plicit).165 E
(feedback from the routers along the path.)100.8 215 Q
(There are a number of proposals for this, ranging)5.5 E
(from a minimal proposal for an IP option that allo)100.8 228 Q
(ws TCP SYN pack)-.275 E(ets to collect)-.11 E
(information from routers along the path about the allo)100.8 241 Q
(wed initial sending rate [J02], to)-.275 E(proposals with more po)100.8
254 Q(wer that require more \214ne-tuned and continuous feedback from)
-.275 E 2.75(routers. These)100.8 267 R(proposals all are some)2.75 E
(what longer)-.275 E(-term proposals than the HighSpeed TCP)-.22 E(prop\
osal in this document, requiring longer lead times and more coordinatio\
n for)100.8 280 Q(deplo)100.8 293 Q
(yment, and will be discussed in later documents.)-.11 E/F1 11
/Times-Bold@0 SF(10.2.)72 332 Q/F2 13/Times-Bold@0 SF(Limiting b)5.5 E
(urstiness on short time scales.)-.26 E F0(Because the congestion windo)
100.8 358 Q 2.75(wa)-.275 G(chie)-2.75 E -.165(ve)-.275 G 2.75(db).165 G
2.75(yaH)-2.75 G(ighSpeed TCP connection could be quite)-2.75 E(lar)
100.8 371 Q(ge, there is a possibility for the sender to send a lar)
-.198 E(ge b)-.198 E(urst of pack)-.22 E(ets in response to a)-.11 E
(single ackno)100.8 384 Q 2.75(wledgement. This)-.275 F
(could happen, for e)2.75 E(xample, when there is congestion or)-.165 E
(reordering on the re)100.8 397 Q -.165(ve)-.275 G
(rse path, and the sender recei).165 E -.165(ve)-.275 G 2.75(sa).165 G
2.75(na)-2.75 G(ckno)-2.75 E(wledgement)-.275 E(ackno)100.8 410 Q
(wledging hundreds or thousands of ne)-.275 E 2.75(wp)-.275 G(ack)-2.75
E 2.75(ets. Such)-.11 F 2.75(ab)2.75 G(urst w)-2.97 E
(ould also result if the)-.11 E(application w)100.8 423 Q(as idle for a\
 short period of time less than a round-trip time, and then)-.11 E
(suddenly had lots of data a)100.8 436 Q -.275(va)-.22 G
(ilable to send.).275 E(In this case, it w)5.5 E(ould be useful for the)
-.11 E(HighSpeed TCP connection to ha)100.8 449 Q .33 -.165(ve s)-.22 H
(ome method for limiting b).165 E(ursts.)-.22 E 1.76 -.88(We d)100.8 475
T 2.75(on).88 G
(ot in this document specify TCP mechanisms for reducing the short-term)
-2.75 E -.22(bu)100.8 488 S 2.75(rstiness. One).22 F(possible mechanism\
 is to use some form of rate-based pacing, and another)2.75 E
(possibility is to use maxb)100.8 501 Q
(urst, which limits the number of pack)-.22 E
(ets that are sent in response)-.11 E(to a single ackno)100.8 514 Q 2.75
(wledgement. W)-.275 F 2.75(ew)-.88 G(ould caution, ho)-2.86 E(we)-.275
E -.165(ve)-.275 G .88 -.44(r, a).165 H -.055(ga).44 G
(inst a permanent reduction).055 E(in the congestion windo)100.8 527 Q
2.75(wa)-.275 G 2.75(sam)-2.75 G(echanism for limiting short-term b)
-2.75 E 2.75(ursts. Such)-.22 F(a)2.75 E(mechanism has been deplo)100.8
540 Q(yed in some TCP stacks, and our vie)-.11 E 2.75(ww)-.275 G
(ould be that using)-2.86 E
(permanent reductions of the congestion windo)100.8 553 Q 2.75(wt)-.275
G 2.75(or)-2.75 G(educe transient b)-2.75 E(ursts w)-.22 E
(ould be a bad)-.11 E(idea [Fl03].)100.8 566 Q F1(10.3.)72 605 Q F2
(Other limitations on windo)5.5 E 3.25(ws)-.13 G(ize.)-3.25 E F0
(The TCP header uses a 16-bit \214eld to report the recei)100.8 631 Q
.33 -.165(ve w)-.275 H(indo).165 E 2.75(ws)-.275 G(ize to the sender)
-2.75 E(.)-.605 E(Unmodi\214ed, this allo)100.8 644 Q(ws a windo)-.275 E
2.75(ws)-.275 G(ize of at most 2**16 = 65K bytes.)-2.75 E -.44(Wi)5.5 G
(th windo).44 E(w)-.275 E(scaling, the maximum windo)100.8 657 Q 2.75
(ws)-.275 G(ize is 2**30 = 1073M bytes [RFC 1323].)-2.75 E(Gi)5.5 E
-.165(ve)-.275 G 2.75(n1).165 G(500-byte)-2.75 E(pack)100.8 670 Q
(ets, this allo)-.11 E(ws a windo)-.275 E 2.75(wo)-.275 G 2.75(fu)-2.75
G 2.75(pt)-2.75 G 2.75(o7)-2.75 G(15,000 pack)-2.75 E(ets.)-.11 E(Flo)72
769 Q 298.141(yd Section)-.11 F 2.75(10.3. [P)2.75 F(age 17])-.165 E 0
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(December 2003)2.75 E(June 2003)116.406 E/F1 11/Times-Bold@0 SF(10.4.)72
85 Q/F2 13/Times-Bold@0 SF(Implementation issues.)5.5 E F0(One implemen\
tation issue that has been raised with HighSpeed TCP is that with conge\
stion)100.8 111 Q(windo)100.8 124 Q
(ws of 4MB or more, the handling of successi)-.275 E .33 -.165(ve S)
-.275 H -.44(AC).165 G 2.75(Kp).44 G(ack)-2.75 E(ets after a pack)-.11 E
(et is)-.11 E(dropped becomes v)100.8 137 Q
(ery time-consuming at the TCP sender [S03].)-.165 E -.88(To)8.25 G 2.75
(mK).88 G(elly')-3.025 E 2.75(sS)-.605 G(calable)-2.75 E
(TCP includes a "SA)100.8 150 Q(CK F)-.44 E(ast P)-.165 E
(ath" patch that addresses this problem.)-.165 E
(The issues addressed in the W)100.8 176 Q
(eb100 project, the Net100 project, and related projects about)-.88 E
(the tuning necessary to achie)100.8 189 Q .33 -.165(ve h)-.275 H
(igh bandwidth data rates with TCP apply to HighSpeed).165 E
(TCP as well [Net100, W)100.8 202 Q(eb100].)-.88 E F1(11.)72 241 Q/F3 14
/Times-Bold@0 SF(Deployment issues.)5.5 E F1(11.1.)72 280 Q F2
(Deployment issues of HighSpeed TCP)5.5 E F0 1.76 -.88(We d)100.8 306 T
2.75(on).88 G(ot claim that the HighSpeed TCP modi\214cation to TCP des\
cribed in this paper is an)-2.75 E
(optimal transport protocol for high-bandwidth en)100.8 319 Q 2.75
(vironments. Based)-.44 F(on our e)2.75 E(xperiences)-.165 E(with HighS\
peed TCP in the NS simulator [NS], on simulation studies [SA03], and on)
100.8 332 Q -.165(ex)100.8 345 S
(perimental reports [ABLLS03,D02,CC03,F03], we belie).165 E .33 -.165
(ve t)-.275 H(hat HighSpeed TCP).165 E(impro)100.8 358 Q -.165(ve)-.165
G 2.75(st).165 G(he performance of TCP in high-bandwidth en)-2.75 E
(vironments, and we are)-.44 E
(documenting it for the bene\214t of the IETF community)100.8 371 Q 5.5
(.W)-.715 G 2.75(ee)-6.38 G(ncourage the use of)-2.75 E(HighSpeed TCP)
100.8 384 Q 2.75(,a)-1.221 G
(nd of its underlying response function, and we further encourage)-2.75
E(feedback about operational e)100.8 397 Q
(xperiences with this or related modi\214cations.)-.165 E 1.76 -.88
(We n)100.8 423 T(ote that in en).88 E
(vironments typical of much of the current Internet, HighSpeed TCP)-.44
E(beha)100.8 436 Q -.165(ve)-.22 G 2.75(se).165 G
(xactly as does Standard TCP today)-2.915 E 5.5(.T)-.715 G
(his is the case an)-5.5 E 2.75(yt)-.165 G(ime the congestion)-2.75 E
(windo)100.8 449 Q 2.75(wi)-.275 G 2.75(sl)-2.75 G(ess than 38 se)-2.75
E(gments.)-.165 E 5.5(Bandwidth A)106.3 475 R(vg Cwnd w \(pkts\))-.814 E
(Increase a\(w\))11 E(Decrease b\(w\))8.25 E 5.5
(--------- -----------------)106.3 488 R 5.5
(------------- -------------)11 F(1.5 Mbps)111.8 501 Q 38.5(12.5 1)24.75
F(0.50)38.5 E(10 Mbps)109.05 514 Q 44(83 1)30.25 F(0.50)38.5 E(100 Mbps)
106.3 527 Q 44(833 6)27.5 F(0.35)38.5 E 2.75(1G)111.8 540 S 22(bps 8333)
-2.75 F 35.75(26 0.22)44 F(10 Gbps)109.05 553 Q 41.25(83333 70)22 F
(0.10)38.5 E -.88(Ta)100.8 579 S
(ble 9: Performance of a HighSpeed TCP connection.).88 E 1.76 -.88(To h)
100.8 605 T(elp calibrate, T).88 E
(able 9 considers a TCP connection with 1500-byte pack)-.88 E(ets, an R)
-.11 E(TT of)-.66 E(100 ms \(including a)100.8 618 Q -.165(ve)-.22 G
(rage queueing delay\), and no competing traf).165 E(\214c, and sho)
-.275 E(ws the)-.275 E -2.475 -.22(av e)100.8 631 T
(rage congestion windo).22 E 2.75(wi)-.275 G 2.75(ft)-2.75 G
(hat TCP connection had a pipe all to itself and fully used)-2.75 E
(the link bandwidth, for a range of bandwidths for the pipe.)100.8 644 Q
(This assumes that the TCP)5.5 E(connection w)100.8 657 Q(ould use T)
-.11 E(able 12 in determining its increase and decrease parameters.)-.88
E(The)5.5 E(\214rst column of T)100.8 670 Q(able 9 gi)-.88 E -.165(ve)
-.275 G 2.75(st).165 G(he bandwidth, and the second column gi)-2.75 E
-.165(ve)-.275 G 2.75(st).165 G(he a)-2.75 E -.165(ve)-.22 G(rage).165 E
(congestion windo)100.8 683 Q 2.75(wwn)-.275 G
(eeded to utilize that bandwidth.)-2.75 E(The third column sho)5.5 E
2.75(wt)-.275 G(he)-2.75 E(increase a\(w\) in se)100.8 696 Q
(gments per R)-.165 E(TT for windo)-.66 E 2.75(ww)-.275 G 5.5(.T)-3.465
G(he fourth column sho)-5.5 E 2.75(wt)-.275 G(he decrease)-2.75 E
(b\(w\) for that windo)100.8 709 Q 2.75(ww\()-.275 G
(where the TCP sender decreases the congestion windo)-2.75 E 2.75(wf)
-.275 G(rom w)-2.75 E(to w\(1-b\(w\)\) se)100.8 722 Q
(gments after a loss e)-.165 E -.165(ve)-.275 G 2.75(nt\). W).165 F 2.75
(en)-.88 G(ote that the actual congestion windo)-2.75 E(w)-.275 E(Flo)72
769 Q 298.141(yd Section)-.11 F 2.75(11.1. [P)2.75 F(age 18])-.165 E 0
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(December 2003)2.75 E(June 2003)116.406 E(when a loss occurs is lik)
100.8 85 Q(ely to be greater than the a)-.11 E -.165(ve)-.22 G
(rage congestion windo).165 E 2.75(wwi)-.275 G 2.75(nc)-2.75 G(olumn)
-2.75 E(2, so the decrease parameter used could be slightly smaller tha\
n the one gi)100.8 98 Q -.165(ve)-.275 G 2.75(ni).165 G 2.75(nc)-2.75 G
(olumn 4)-2.75 E(of T)100.8 111 Q(able 9.)-.88 E -.88(Ta)100.8 137 S
(ble 9 sho).88 E(ws that a HighSpeed TCP o)-.275 E -.165(ve)-.165 G 2.75
(ra1).165 G 2.75(0M)-2.75 G(bps link beha)-2.75 E -.165(ve)-.22 G 2.75
(se).165 G(xactly the same as a)-2.915 E(Standard TCP connection, e)
100.8 150 Q -.165(ve)-.275 G 2.75(ni).165 G 2.75(nt)-2.75 G
(he absence of competing traf)-2.75 E 2.75(\214c. One)-.275 F
(can think of the)2.75 E(congestion windo)100.8 163 Q 2.75(ws)-.275 G
(taying generally in the range of 55 to 110 se)-2.75 E(gments, with the)
-.165 E(HighSpeed TCP beha)100.8 176 Q(vior being e)-.22 E
(xactly the same as the beha)-.165 E(vior of Standard TCP)-.22 E 5.5
(.\()-1.221 G(If the)-5.5 E(congestion windo)100.8 189 Q 2.75(wi)-.275 G
2.75(se)-2.75 G -.165(ve)-3.025 G 2.75(r1).165 G(28 se)-2.75 E
(gments or more, then the HighSpeed TCP increases by)-.165 E(tw)100.8
202 Q 2.75(os)-.11 G -.165(eg)-2.75 G(ments per R).165 E
(TT instead of by one, and uses a decrease parameter of 0.44 instead of)
-.66 E(0.50.\))100.8 215 Q -.88(Ta)100.8 241 S(ble 9 sho).88 E
(ws that for a HighSpeed TCP connection o)-.275 E -.165(ve)-.165 G 2.75
(ra1).165 G(00 Mbps link, with no)-2.75 E(competing traf)100.8 254 Q
(\214c, HighSpeed TCP beha)-.275 E -.165(ve)-.22 G 2.75(sr).165 G
(oughly as aggressi)-2.75 E -.165(ve)-.275 G(ly as six parallel TCP).165
E(connections, increasing its congestion windo)100.8 267 Q 2.75(wb)-.275
G 2.75(yr)-2.75 G(oughly six se)-2.75 E(gments per round-trip)-.165 E(t\
ime, and with a decrease parameter of roughly 1/3 \(corresponding to de\
creasing do)100.8 280 Q(wn to)-.275 E
(2/3-rds of its old congestion windo)100.8 293 Q 1.43 -.715(w, r)-.275 H
(ather than to half, in response to a loss e).715 E -.165(ve)-.275 G
(nt\).).165 E -.165(Fo)100.8 319 S 2.75(raS).165 G
(tandard TCP connection in this en)-2.75 E
(vironment, the congestion windo)-.44 E 2.75(wc)-.275 G(ould be)-2.75 E
(thought of as v)100.8 332 Q
(arying generally in the range of 550 to 1100 se)-.275 E
(gments, with an a)-.165 E -.165(ve)-.22 G(rage).165 E(pack)100.8 345 Q
(et drop rate of 2.2 * 10^-6 \(corresponding to a bit error rate of 1.8\
 * 10^-10\), or)-.11 E(equi)100.8 358 Q -.275(va)-.275 G(lently).275 E
2.75(,r)-.715 G(oughly 55 seconds between congestion e)-2.75 E -.165(ve)
-.275 G 2.75(nts. While).165 F 2.75(aS)2.75 G(tandard TCP)-2.75 E
(connection could sustain such a lo)100.8 371 Q 2.75(wp)-.275 G(ack)
-2.75 E(et drop rate in a carefully controlled en)-.11 E(vironment)-.44
E(with minimal competing traf)100.8 384 Q(\214c, we w)-.275 E
(ould contend that in an uncontrolled best-ef)-.11 E(fort)-.275 E(en)
100.8 397 Q(vironment with e)-.44 E -.165(ve)-.275 G 2.75(nas).165 G
(mall amount of competing traf)-2.75 E(\214c, the occasional congestion)
-.275 E -2.365 -.275(ev e)100.8 410 T(nts from smaller competing \215o)
.275 E(ws could easily be suf)-.275 E(\214cient to pre)-.275 E -.165(ve)
-.275 G(nt a Standard TCP).165 E<8d6f>100.8 423 Q 2.75(ww)-.275 G
(ith no lo)-2.75 E(wer)-.275 E
(-speed bottlenecks from fully utilizing the a)-.22 E -.275(va)-.22 G
(ilable bandwidth of the).275 E(underutilized 100 Mbps link.)100.8 436 Q
(That is, we w)100.8 462 Q(ould content that in the en)-.11 E
(vironment of 100 Mbps links with a signi\214cant)-.44 E(amount of a)
100.8 475 Q -.275(va)-.22 G(ilable bandwidth, Standard TCP w).275 E
(ould sometimes be unable to fully utilize)-.11 E
(the link bandwidth, and that HighSpeed TCP w)100.8 488 Q
(ould be an impro)-.11 E -.165(ve)-.165 G(ment in this re).165 E -.055
(ga)-.165 G 2.75(rd. W).055 F(e)-.88 E -.11(wo)100.8 501 S
(uld further contend that in this en).11 E(vironment, the beha)-.44 E
(vior of HighSpeed TCP is)-.22 E(suf)100.8 514 Q
(\214ciently close to that of Standard TCP that HighSpeed TCP w)-.275 E
(ould be safe to deplo)-.11 E 2.75(yi)-.11 G(n)-2.75 E
(the current Internet.)100.8 527 Q/F1 11/Times-Bold@0 SF(11.2.)72 579 Q
/F2 13/Times-Bold@0 SF(Deployment issues of Scalable TCP)5.5 E F0 1.76
-.88(We b)100.8 605 T(elie).88 E .33 -.165(ve t)-.275 H
(hat Scalable TCP and HighSpeed TCP ha).165 E .33 -.165(ve s)-.22 H(uf)
.165 E(\214ciently similar response)-.275 E(functions that the)100.8 618
Q 2.75(yc)-.165 G(ould easily coe)-2.75 E(xist in the Internet.)-.165 E
(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44(r, w).165 H 2.75(eh).44 G
-2.475 -.22(av e)-2.75 H(not in)2.97 E -.165(ve)-.44 G(stig).165 E(ated)
-.055 E(Scalable TCP suf)100.8 631 Q(\214ciently to be able to claim, i\
n this document, that Scalable TCP is safe)-.275 E
(for a widespread deplo)100.8 644 Q(yment in the current Internet.)-.11
E(Flo)72 769 Q 298.141(yd Section)-.11 F 2.75(11.2. [P)2.75 F(age 19])
-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E 5.5(Bandwidth A)106.3 85 R
(vg Cwnd w \(pkts\))-.814 E(Increase a\(w\))11 E(Decrease b\(w\))8.25 E
5.5(--------- -----------------)106.3 98 R 5.5
(------------- -------------)11 F(1.5 Mbps)111.8 111 Q 38.5(12.5 1)24.75
F(0.50)38.5 E(10 Mbps)109.05 124 Q 44(83 0.4)30.25 F(0.125)33 E
(100 Mbps)106.3 137 Q 44(833 4.1)27.5 F(0.125)33 E 2.75(1G)111.8 150 S
22(bps 8333)-2.75 F 30.25(41.6 0.125)44 F(10 Gbps)109.05 163 Q 38.5
(83333 416.5)22 F(0.125)33 E -.88(Ta)100.8 189 S
(ble 10: Performance of a Scalable TCP connection.).88 E -.88(Ta)100.8
215 S(ble 10 sho).88 E
(ws the performance of a Scalable TCP connection with 1500-byte pack)
-.275 E(ets, an)-.11 E -.66(RT)100.8 228 S 2.75(To).66 G 2.75(f1)-2.75 G
(00 ms \(including a)-2.75 E -.165(ve)-.22 G
(rage queueing delay\), and no competing traf).165 E 2.75(\214c. The)
-.275 F(TCP)2.75 E(connection is assumed to use delayed ackno)100.8 241
Q 2.75(wledgements. The)-.275 F(\214rst column of T)2.75 E(able 10)-.88
E(gi)100.8 254 Q -.165(ve)-.275 G 2.75(st).165 G
(he bandwidth, the second column gi)-2.75 E -.165(ve)-.275 G 2.75(st)
.165 G(he a)-2.75 E -.165(ve)-.22 G(rage congestion windo).165 E 2.75
(wn)-.275 G(eeded to)-2.75 E
(utilize that bandwidth, and the third and fourth columns gi)100.8 267 Q
.33 -.165(ve t)-.275 H(he increase and decrease).165 E(parameters.)100.8
280 Q(Note that e)100.8 306 Q -.165(ve)-.275 G 2.75(ni).165 G 2.75(na)
-2.75 G 2.75(ne)-2.75 G -.44(nv)-2.75 G
(ironment with a 10 Mbps link, Scalable TCP').44 E 2.75(sb)-.605 G(eha)
-2.75 E(vior is)-.22 E(considerably dif)100.8 319 Q
(ferent from that of Standard TCP)-.275 E 5.5(.T)-1.221 G
(he increase parameter is smaller than)-5.5 E(that of Standard TCP)100.8
332 Q 2.75(,a)-1.221 G
(nd the decrease is smaller also, 1/8-th instead of 1/2.)-2.75 E
(That is, for 10)5.5 E(Mbps links, Scalable TCP increases less aggressi)
100.8 345 Q -.165(ve)-.275 G(ly than Standard TCP or HighSpeed).165 E
(TCP)100.8 358 Q 2.75(,b)-1.221 G(ut decreases less aggressi)-2.97 E
-.165(ve)-.275 G(ly as well.).165 E(In an en)100.8 384 Q(vironment with\
 a 100 Mbps link, Scalable TCP has an increase parameter of)-.44 E
(roughly four se)100.8 397 Q(gments per round-trip time, with the same \
decrease parameter of 1/8-th.)-.165 E(A)5.5 E(comparison of T)100.8 410
Q(ables 9 and 10 sho)-.88 E
(ws that for this scenario of 100 Mbps links, HighSpeed)-.275 E
(TCP increases more aggressi)100.8 423 Q -.165(ve)-.275 G
(ly than Scalable TCP).165 E(.)-1.221 E(Ne)100.8 449 Q
(xt we consider the relati)-.165 E .33 -.165(ve f)-.275 H
(airness between Standard TCP).055 E 2.75(,H)-1.221 G(ighSpeed TCP and)
-2.75 E(Scalable TCP)100.8 462 Q 5.5(.T)-1.221 G(he relati)-5.5 E .33
-.165(ve f)-.275 H(airness between HighSpeed TCP and Standard TCP w).055
E(as)-.11 E(sho)100.8 475 Q(wn in T)-.275 E
(able 5 earlier in this document, and the relati)-.88 E .33 -.165(ve f)
-.275 H(airness between Scalable TCP).055 E(and Standard TCP w)100.8 488
Q(as sho)-.11 E(wn in T)-.275 E(able 8.)-.88 E -.165(Fo)5.5 G(llo).165 E
(wing the approach in Section 6, for a gi)-.275 E -.165(ve)-.275 G(n)
.165 E(pack)100.8 501 Q
(et drop rate p, for p < 10^-3, we can estimate the relati)-.11 E .33
-.165(ve f)-.275 H(airness between Scalable).055 E
(and HighSpeed TCP as W_Scalable/W_HighSpeed.)100.8 514 Q(This relati)
5.5 E .33 -.165(ve f)-.275 H(airness is sho).055 E(wn in)-.275 E -.88
(Ta)100.8 527 S(ble 11 belo).88 E 4.18 -.715(w. T)-.275 H
(he bandwidth in the last column of T).715 E(able 11 is the aggre)-.88 E
-.055(ga)-.165 G(te bandwidth).055 E(of the tw)100.8 540 Q 2.75(oc)-.11
G(ompeting \215o)-2.75 E(ws gi)-.275 E -.165(ve)-.275 G 2.75(n1).165 G
(00 ms round-trip times and 1500-byte pack)-2.75 E(ets.)-.11 E -.165(Pa)
106.3 566 S(ck).165 E(et Drop Rate P)-.11 E -.165(Fa)8.25 G 2.75
(irness Aggre).165 F -.055(ga)-.165 G(te W).055 E(indo)-.44 E 5.5(wB)
-.275 G(andwidth)-5.5 E 5.5(------------------ --------)106.3 579 R 2.75
(---------------- ---------)5.5 F 30.25(10^-2 1.0)120.05 592 R 19.25
(24 2.8)38.5 F(Mbps)2.75 E 30.25(10^-3 1.0)120.05 605 R 19.25(76 9.1)
38.5 F(Mbps)2.75 E 30.25(10^-4 1.4)120.05 618 R 16.5(643 77.1)35.75 F
(Mbps)2.75 E 30.25(10^-5 2.1 5595)120.05 631 R(671.4 Mbps)16.5 E 30.25
(10^-6 3.1)120.05 644 R 19.25(50279 6.0)30.25 F(Gbps)2.75 E 30.25
(10^-7 4.5)120.05 657 R 16.5(463981 55.7)27.5 F(Gbps)2.75 E -.88(Ta)
100.8 683 S(ble 11: Relati).88 E .33 -.165(ve Fa)-.275 H
(irness between the Scalable and HighSpeed Response Functions.).165 E
(The second ro)100.8 722 Q 2.75(wo)-.275 G 2.75(fT)-2.75 G(able 11 sho)
-3.63 E(ws that for a Scalable TCP and a HighSpeed TCP \215o)-.275 E(w)
-.275 E(Flo)72 769 Q 298.141(yd Section)-.11 F 2.75(11.2. [P)2.75 F
(age 20])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E(competing in an en)100.8 85 Q
(vironment with 100 ms R)-.44 E(TTs and a 10 Mbps pipe, the tw)-.66 E
2.75<6f8d>-.11 G -.275(ow)-2.75 G 2.75(sw).275 G(ould)-2.86 E(recei)
100.8 98 Q .33 -.165(ve e)-.275 H(ssentially the same bandwidth.).165 E
(The ne)5.5 E(xt ro)-.165 E 2.75(ws)-.275 G(ho)-2.75 E
(ws that for a Scalable TCP and a)-.275 E(HighSpeed TCP \215o)100.8 111
Q 2.75(wc)-.275 G(ompeting in an en)-2.75 E(vironment with 100 ms R)-.44
E(TTs and a 100 Mbps)-.66 E(pipe, the Scalable TCP \215o)100.8 124 Q
2.75(ww)-.275 G(ould recei)-2.86 E .33 -.165(ve r)-.275 H
(oughly 50% more bandwidth than w).165 E(ould)-.11 E(HighSpeed TCP)100.8
137 Q 5.5(.T)-1.221 G(able 11 sho)-6.38 E(ws the relati)-.275 E .33
-.165(ve f)-.275 H(airness in higher).055 E(-bandwidth en)-.22 E
(vironments as)-.44 E 2.75(well. This)100.8 150 R(relati)2.75 E .33
-.165(ve f)-.275 H(airness seems suf).055 E
(\214cient that there should be no problems with Scalable)-.275 E
(TCP and HighSpeed TCP coe)100.8 163 Q(xisting in the same en)-.165 E
(vironment as Experimental v)-.44 E(ariants of)-.275 E(TCP)100.8 176 Q
(.)-1.221 E 1.76 -.88(We n)100.8 202 T
(ote that one question that requires more in).88 E -.165(ve)-.44 G(stig)
.165 E(ation with Scalable TCP is that of)-.055 E(con)100.8 215 Q -.165
(ve)-.44 G -.198(rg).165 G(ence to f).198 E(airness in en)-.11 E
(vironments with Drop-T)-.44 E(ail queue management.)-.88 E/F1 11
/Times-Bold@0 SF(12.)72 254 Q/F2 14/Times-Bold@0 SF(Related W)5.5 E
(ork in HighSpeed TCP)-1.05 E(.)-1.54 E F0
(HighSpeed TCP has been separately in)100.8 280 Q -.165(ve)-.44 G(stig)
.165 E(ated in simulations by Sylvia Ratnasamy and)-.055 E(by Ev)100.8
293 Q(andro de Souza [SA03].)-.275 E(The simulations in [SA03] v)5.5 E
(erify the f)-.165 E(airness properties of)-.11 E
(HighSpeed TCP when sharing a link with Standard TCP)100.8 306 Q(.)
-1.221 E(These simulations e)100.8 332 Q(xplore the relati)-.165 E .33
-.165(ve f)-.275 H(airness of HighSpeed TCP \215o).055 E
(ws when competing)-.275 E(with Standard TCP)100.8 345 Q 5.5(.T)-1.221 G
(he simulation en)-5.5 E(vironment includes background forw)-.44 E
(ard and)-.11 E(re)100.8 358 Q -.165(ve)-.275 G(rse-path TCP traf).165 E
(\214c limited by the TCP recei)-.275 E .33 -.165(ve w)-.275 H(indo).165
E 1.43 -.715(w, a)-.275 H(long with a small amount of).715 E(forw)100.8
371 Q(ard and re)-.11 E -.165(ve)-.275 G(rse-path traf).165 E
(\214c from the web traf)-.275 E(\214c generator)-.275 E 5.5(.M)-.605 G
(ost of the simulations so)-5.5 E -.11(fa)100.8 384 S 2.75(re).11 G(xpl\
ore performance on a simple dumbbell topology with a 1 Gbps link with a)
-2.915 E(propag)100.8 397 Q(ation delay of 50 ms.)-.055 E
(Simulations ha)5.5 E .33 -.165(ve b)-.22 H(een run with Adapti).165 E
.33 -.165(ve R)-.275 H(ED and with).165 E(DropT)100.8 410 Q
(ail queue management.)-.88 E(The simulations in [SA03] e)100.8 436 Q
(xplore performance with a v)-.165 E(arying number of competing)-.275 E
<8d6f>100.8 449 Q(ws, with the competing traf)-.275 E
(\214c being all standard TCP; all HighSpeed TCP; or a mix of)-.275 E
(standard and HighSpeed TCP)100.8 462 Q 5.5(.F)-1.221 G
(or the simulations in [SA03] with RED queue)-5.665 E
(management, the relati)100.8 475 Q .33 -.165(ve f)-.275 H
(airness between standard and HighSpeed TCP is consistent with).055 E
(the relati)100.8 488 Q .33 -.165(ve f)-.275 H(airness predicted in T)
.055 E(able 5.)-.88 E -.165(Fo)5.5 G 2.75(rt).165 G
(he simulations with Drop T)-2.75 E(ail queues, the)-.88 E(relati)100.8
501 Q .33 -.165(ve f)-.275 H(airness is more sk).055 E -.275(ew)-.11 G
(ed, with the HighSpeed TCP \215o).275 E(ws recei)-.275 E(ving an e)
-.275 E -.165(ve)-.275 G 2.75(nl).165 G(ar)-2.75 E(ger)-.198 E
(share of the link bandwidth.)100.8 514 Q(This is not surprising;)5.5 E
(with Acti)5.5 E .33 -.165(ve Q)-.275 H(ueue Management at the).165 E
(congested link, the fraction of pack)100.8 527 Q(et drops recei)-.11 E
-.165(ve)-.275 G 2.75(db).165 G 2.75(ye)-2.75 G(ach \215o)-2.75 E 2.75
(ws)-.275 G(hould be roughly)-2.75 E(proportional to that \215o)100.8
540 Q(w')-.275 E 2.75(ss)-.605 G
(hare of the link bandwidth, while this property no longer holds)-2.75 E
(with Drop T)100.8 553 Q(ail queue management.)-.88 E 1.76 -.88(We a)5.5
H(lso note that relati).88 E .33 -.165(ve f)-.275 H
(airness in simulations with).055 E(Drop T)100.8 566 Q(ail queue manage\
ment can sometimes depend on small details of the simulation)-.88 E
(scenario, and that Drop T)100.8 579 Q
(ail simulations need special care to a)-.88 E -.22(vo)-.22 G
(id phase ef).22 E(fects [F92].)-.275 E([SA03] e)100.8 605 Q
(xplores the bandwidth `stolen' by HighSpeed TCP from standard TCP by)
-.165 E -.165(ex)100.8 618 S
(ploring the fraction of the link bandwidth N standard TCP \215o).165 E
(ws recei)-.275 E .33 -.165(ve w)-.275 H(hen competing).165 E(ag)100.8
631 Q(ainst N other standard TCP \215o)-.055 E
(ws, and comparing this to the fraction of the link)-.275 E
(bandwidth the N standard TCP \215o)100.8 644 Q(ws recei)-.275 E .33
-.165(ve w)-.275 H(hen competing ag).165 E(ainst N HighSpeed TCP)-.055 E
<8d6f>100.8 657 Q 2.75(ws. F)-.275 F
(or the 1 Gbps simulation scenarios dominated by long-li)-.165 E -.165
(ve)-.275 G 2.75(dt).165 G(raf)-2.75 E(\214c, a small number)-.275 E
(of standard TCP \215o)100.8 670 Q(ws are able to achie)-.275 E .33
-.165(ve h)-.275 H(igh link utilization, and the HighSpeed TCP).165 E
<8d6f>100.8 683 Q(ws can be vie)-.275 E
(wed as stealing bandwidth from the competing standard TCP \215o)-.275 E
(ws, as)-.275 E(predicted in Section 6 on the F)100.8 696 Q
(airness Implications of the HighSpeed Response Function.)-.165 E(Ho)
100.8 709 Q(we)-.275 E -.165(ve)-.275 G .88 -.44(r, [).165 H(SA03] sho)
.44 E(ws that when e)-.275 E -.165(ve)-.275 G 2.75(nas).165 G
(mall fraction of the link bandwidth is used by)-2.75 E(more b)100.8 722
Q(ursty)-.22 E 2.75(,s)-.715 G
(hort TCP connections, the standard TCP \215o)-2.75 E
(ws are unable to achie)-.275 E .33 -.165(ve h)-.275 H(igh).165 E(Flo)72
769 Q 306.391(yd Section)-.11 F 2.75(12. [P)2.75 F(age 21])-.165 E 0 Cg
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(December 2003)2.75 E(June 2003)116.406 E
(link utilization, and the HighSpeed TCP \215o)100.8 85 Q
(ws in this case are not `stealing' bandwidth)-.275 E
(from the standard TCP \215o)100.8 98 Q(ws, b)-.275 E
(ut instead are using bandwidth that otherwise w)-.22 E(ould not be)-.11
E(utilized.)100.8 111 Q
(The conclusions of [SA03] are that "HighSpeed TCP beha)100.8 137 Q
-.165(ve)-.22 G 2.75(da).165 G 2.75(sf)-2.75 G(orseen by its response)
-2.75 E(function, and appears to be a real and viable option for use on\
 high-speed wide area TCP)100.8 150 Q(connections.")100.8 163 Q
(Future w)100.8 189 Q(ork that could be e)-.11 E
(xplored in more detail includes con)-.165 E -.165(ve)-.44 G -.198(rg)
.165 G(ence times after ne).198 E(w)-.275 E<8d6f>100.8 202 Q
(ws start-up; reco)-.275 E -.165(ve)-.165 G
(ry time after a transient outage; the response to sudden se).165 E
-.165(ve)-.275 G(re).165 E(congestion, and in)100.8 215 Q -.165(ve)-.44
G(stig).165 E(ations of the potential for oscillations.)-.055 E 1.76
-.88(We i)5.5 H -.44(nv).88 G(ite contrib).44 E(utions)-.22 E
(from others in this w)100.8 228 Q(ork.)-.11 E/F1 11/Times-Bold@0 SF
(13.)72 267 Q/F2 14/Times-Bold@0 SF(Relationship to other W)5.5 E(ork.)
-1.05 E F0
(Our assumption is that HighSpeed TCP will be used with the TCP SA)100.8
293 Q(CK option, and also)-.44 E(with the increased Initial W)100.8 306
Q(indo)-.44 E 2.75(wo)-.275 G 2.75(ft)-2.75 G(hree or four se)-2.75 E
(gments, as allo)-.165 E(wed by [RFC3390].)-.275 E -.165(Fo)100.8 319 S
2.75(rp).165 G(aths that ha)-2.75 E .33 -.165(ve s)-.22 H
(ubstantial reordering, TCP performance w).165 E(ould be greatly impro)
-.11 E -.165(ve)-.165 G 2.75(db).165 G(y)-2.75 E
(some of the mechanisms still in the research stages for rob)100.8 332 Q
(ust performance in the presence)-.22 E(of reordered pack)100.8 345 Q
(ets.)-.11 E(Our vie)100.8 371 Q 2.75(wi)-.275 G 2.75(st)-2.75 G
(hat HighSpeed TCP is lar)-2.75 E
(gely orthogonal to proposals for higher PMTU \(P)-.198 E(ath)-.165 E
(MTU\) v)100.8 384 Q(alues [M02].)-.275 E(Unlik)5.5 E 2.75(ec)-.11 G
(hanges to the PMTU, HighSpeed TCP does not require an)-2.75 E(y)-.165 E
(changes in the netw)100.8 397 Q(ork or at the TCP recei)-.11 E -.165
(ve)-.275 G .88 -.44(r, a).165 H(nd w).44 E
(orks well in the current Internet.)-.11 E(Our)5.5 E
(assumption is that HighSpeed TCP w)100.8 410 Q(ould be useful e)-.11 E
-.165(ve)-.275 G 2.75(nw).165 G(ith lar)-2.75 E(ger v)-.198 E
(alues for the PMTU.)-.275 E(Unlik)100.8 423 Q 2.75(et)-.11 G
(he current congestion windo)-2.75 E 1.43 -.715(w, t)-.275 H(he PMTU gi)
.715 E -.165(ve)-.275 G 2.75(sn).165 G 2.75(oi)-2.75 G
(nformation about the)-2.75 E(bandwidth-delay product a)100.8 436 Q
-.275(va)-.22 G(ilable to that particular \215o).275 E -.715(w.)-.275 G
2.75(Ar)100.8 462 S(elated approach is that of a virtual MTU, where the\
 actual MTU of the path might be)-2.75 E(limited [VMSS,S02].)100.8 475 Q
(The virtual MTU approach has not been fully in)5.5 E -.165(ve)-.44 G
(stig).165 E(ated, and we)-.055 E(do not e)100.8 488 Q
(xplore the virtual MTU approach further in this document.)-.165 E F1
(14.)72 527 Q F2(Conclusions.)5.5 E F0
(This document has proposed HighSpeed TCP)100.8 553 Q 2.75(,am)-1.221 G
(odi\214cation to TCP')-2.75 E 2.75(sc)-.605 G(ongestion control)-2.75 E
(mechanism for use with TCP connections with lar)100.8 566 Q
(ge congestion windo)-.198 E 2.75(ws. W)-.275 F 2.75(eh)-.88 G -2.475
-.22(av e)-2.75 H -.165(ex)100.8 579 S
(plored this proposal in simulations, and others ha).165 E .33 -.165
(ve ex)-.22 H(plored HighSpeed TCP with).165 E -.165(ex)100.8 592 S
(periments, and we belie).165 E .33 -.165(ve H)-.275 H
(ighSpeed TCP to be safe to deplo).165 E 2.75(yo)-.11 G 2.75(nt)-2.75 G
(he current Internet.)-2.75 E 1.76 -.88(We w)100.8 605 T
(ould welcome additional analysis, simulations, and particularly).77 E
2.75(,e)-.715 G(xperimentation.)-2.915 E
(More information on simuations and e)100.8 618 Q(xperiments is a)-.165
E -.275(va)-.22 G(ilable from the HighSpeed TCP).275 E -.88(We)100.8 631
S 2.75(bP).88 G(age [HSTCP].)-2.915 E(There are se)5.5 E -.165(ve)-.275
G(ral independent implementations of HighSpeed TCP).165 E
([D02,F03] and of Scalable TCP [K03] for further in)100.8 644 Q -.165
(ve)-.44 G(stig).165 E(ation.)-.055 E 1.76 -.88(We a)100.8 670 T(re bri\
nging this proposal to the IETF to be considered as an Experimental RFC\
.).88 E(Flo)72 769 Q 306.391(yd Section)-.11 F 2.75(14. [P)2.75 F
(age 22])-.165 E 0 Cg EP
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(December 2003)2.75 E(June 2003)116.406 E/F1 11/Times-Bold@0 SF(15.)72
85 Q/F2 14/Times-Bold@0 SF(Ackno)5.5 E(wledgements)-.14 E F0
(The HighSpeed TCP proposal is from joint w)100.8 111 Q
(ork with Sylvia Ratnasamy and Scott Shenk)-.11 E(er)-.11 E(\(and w)
100.8 124 Q(as initiated by Scott Shenk)-.11 E 2.75(er\). Additional)
-.11 F(in)2.75 E -.165(ve)-.44 G(stig).165 E
(ations of HighSpeed TCP were)-.055 E(joint w)100.8 137 Q(ork with Ev)
-.11 E(andro de Souza and Deb Ag)-.275 E(arw)-.055 E 2.75(al. W)-.11 F
2.75(et)-.88 G(hank T)-2.75 E(om Dunig)-.88 E(an for the)-.055 E
(implementation in the Linux 2.4.16 W)100.8 150 Q(eb100 k)-.88 E
(ernel, and for resulting e)-.11 E(xperimentation with)-.165 E
(HighSpeed TCP)100.8 163 Q 5.5(.W)-1.221 G 2.75(ea)-6.38 G
(re grateful to the End-to-End Research Group, the members of the)-2.75
E -.385(Tr)100.8 176 S(ansport Area W).385 E
(orking Group, and to members of the IP)-.88 E(AM program in Lar)-1.012
E(ge Scale)-.198 E(Communication Netw)100.8 189 Q(orks for feedback.)
-.11 E 1.76 -.88(We t)5.5 H(hank Glenn V).88 E
(innicombe for framing the)-.66 E
(Linear response function in the parameters of HighSpeed TCP)100.8 202 Q
5.5(.W)-1.221 G 2.75(ea)-6.38 G(re also grateful for)-2.75 E(contrib)
100.8 215 Q(utions and feedback from the follo)-.22 E(wing indi)-.275 E
(viduals: Les Cottrell, Mitchell Erblich,)-.275 E(Jef)100.8 228 Q(fre)
-.275 E 2.75(yH)-.165 G(su, T)-2.75 E(om K)-.88 E(elly)-.275 E 2.75(,J)
-.715 G(itendra P)-2.75 E(adh)-.165 E(ye, Andre)-.055 E 2.75(wR)-.275 G
(eiter)-2.75 E 2.75(,S)-.44 G(tanisla)-2.75 E 2.75(vS)-.22 G(haluno)
-2.75 E 1.43 -.715(v, A)-.165 H(le).715 E 2.75(xS)-.165 G(olan,)-2.75 E
-.165(Pa)100.8 241 S(ul Sutter).165 E 2.75(,B)-.44 G(rian T)-2.75 E
(ierne)-.385 E 1.43 -.715(y, J)-.165 H(oe T).715 E(ouch.)-.88 E F1(16.)
72 280 Q F2(Normati)5.5 E .28 -.14(ve R)-.14 H(efer).14 E(ences)-.252 E
F0([RFC2581] M. Allman, V)100.8 306 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
(ns, "TCP Congestion Control", RFC 2581,).165 E(April 1999.)100.8 319 Q
F1(17.)72 358 Q F2(Inf)5.5 E(ormati)-.35 E .28 -.14(ve R)-.14 H(efer).14
E(ences)-.252 E F0([ABLLS03] A. Anton)100.8 384 Q 1.43 -.715(y, J)-.165
H 2.75(.B).715 G(lom, C. de Laat, J. Lee, and W)-2.75 E 2.75(.S)-1.012 G
(jouw)-2.75 E 2.75(,M)-.715 G(acroscopic)-2.75 E(Examination of TCP Flo)
100.8 397 Q(ws o)-.275 E -.165(ve)-.165 G 2.75(rT).165 G
(ransatlantic Links, January 2003.)-3.135 E(URL)5.5 E
("http://carol.wins.uv)100.8 410 Q
(a.nl/%7Edelaat/techrep-2003-2-tcp.pdf".)-.275 E
([BBFS01] Deepak Bansal, Hari Balakrishnan, Sally Flo)100.8 436 Q
(yd, and Scott Shenk)-.11 E(er)-.11 E 2.75(,")-.44 G(Dynamic)-2.75 E
(Beha)100.8 449 Q(vior of Slo)-.22 E(wly-Responsi)-.275 E .33 -.165
(ve C)-.275 H(ongestion Control Algorithms", SIGCOMM 2001,).165 E
(August 2001.)100.8 462 Q([CC03] F)100.8 488 Q(abrizio Coccetti and Les\
 Cottrell, TCP Stack Measurements on Lightly Loaded)-.165 E -.77(Te)
100.8 501 S(stbeds, 2003.).77 E
(URL "http://www-iepm.slac.stanford.edu/monitoring/b)5.5 E(ulk/f)-.22 E
(ast/".)-.11 E([CJ89] D. Chiu and R. Jain, "Analysis of the Increase an\
d Decrease Algorithms for)100.8 527 Q(Congestion A)100.8 540 Q -.22(vo)
-.814 G(idance in Computer Netw).22 E(orks", Computer Netw)-.11 E
(orks and ISDN Systems,)-.11 E -1.419(Vo)100.8 553 S
(l. 17, pp. 1-14, 1989.)1.419 E([CO98] J. Cro)100.8 579 Q(wcroft and P)
-.275 E 2.75(.O)-1.221 G(echslin, "Dif)-2.75 E
(ferentiated End-to-end Services using a)-.275 E -.88(We)100.8 592 S
(ighted Proportional F).88 E(air Share TCP", Computer Communication Re)
-.165 E(vie)-.275 E 1.43 -.715(w, 2)-.275 H(8\(3\):53--69,).715 E(1998.)
100.8 605 Q([D02] T)100.8 631 Q(om Dunig)-.88 E(an, Flo)-.055 E(yd')-.11
E 2.75(sT)-.605 G(CP slo)-2.75 E(w-start and AIMD mods, URL)-.275 E
("http://www)100.8 644 Q(.csm.ornl.go)-.715 E(v/~dunig)-.165 E
(an/net100/\215o)-.055 E(yd.html".)-.11 E([F03] Gareth F)100.8 670 Q
(aire)-.165 E 1.43 -.715(y, H)-.165 H(igh-Speed TCP).715 E 2.75(,2)
-1.221 G 2.75(003. URL)-2.75 F("http://www)100.8 683 Q
(.hep.man.ac.uk/u/g)-.715 E(arethf/hstcp/".)-.055 E([F92] S. Flo)100.8
709 Q(yd and V)-.11 E 2.75(.J)-1.419 G(acobson, On T)-2.75 E(raf)-.385 E
(\214c Phase Ef)-.275 E(fects in P)-.275 E(ack)-.165 E(et-Switched Gate)
-.11 E -.11(wa)-.275 G(ys,).11 E(Internetw)100.8 722 Q
(orking: Research and Experience, V)-.11 E
(.3 N.3, September 1992, p.115-156.)-1.419 E(URL)5.5 E(Flo)72 769 Q
306.391(yd Section)-.11 F 2.75(17. [P)2.75 F(age 23])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 66.092(-DRAFT Expires:)-1.012 F
(December 2003)2.75 E(June 2003)116.406 E("http://www)100.8 85 Q(.icir)
-.715 E(.or)-.605 E(g/\215o)-.198 E(yd/papers.html".)-.11 E
([Fl03] Sally Flo)100.8 111 Q(yd, "Re: [Tsvwg] taking Ne)-.11 E
(wReno \(RFC 2582\) to Proposed Standard",)-.275 E(Email to the tsvwg m\
ailing list, May 14, 2003, URLs "http://www1.ietf.or)100.8 124 Q
(g/mail-)-.198 E(archi)100.8 137 Q -.165(ve)-.275 G(/w).165 E
(orking-groups/tsvwg/current/msg04086.html" and "http://www1.ietf.or)
-.11 E(g/mail-)-.198 E(archi)100.8 150 Q -.165(ve)-.275 G(/w).165 E
(orking-groups/tsvwg/current/msg04087.html".)-.11 E([FF98] Flo)100.8 176
Q(yd, S., and F)-.11 E
(all, K., "Promoting the Use of End-to-End Congestion Control in)-.165 E
(the Internet", IEEE/A)100.8 189 Q(CM T)-.44 E(ransactions on Netw)-.385
E(orking, August 1999.)-.11 E([FRS02] Sally Flo)100.8 215 Q
(yd, Sylvia Ratnasamy)-.11 E 2.75(,a)-.715 G(nd Scott Shenk)-2.75 E(er)
-.11 E 2.75(,")-.44 G(Modifying TCP')-2.75 E 2.75(sC)-.605 G(ongestion)
-2.75 E(Control for High Speeds", May 2002.)100.8 228 Q(URL "http://www)
5.5 E(.icir)-.715 E(.or)-.605 E(g/\215o)-.198 E(yd/notes.html".)-.11 E
([GRK99] P)100.8 254 Q(anos Ge)-.165 E
(vros, Fulvio Risso and Peter Kirstein, "Analysis of a Method for)-.275
E(Dif)100.8 267 Q(ferential TCP Service" In Proceedings of the IEEE GLO\
BECOM'99, Symposium on)-.275 E
(Global Internet , December 1999, Rio de Janeiro, Brazil.)100.8 280 Q
([GV02] S. Gorinsk)100.8 306 Q 2.75(ya)-.165 G(nd H. V)-2.75 E
(in, "Extended Analysis of Binary Adjustment Algorithms",)-.66 E -.77
(Te)100.8 319 S
(chnical Report TR2002-39, Department of Computer Sciences, The Uni).77
E -.165(ve)-.275 G(rsity of T).165 E -.165(ex)-.77 G(as).165 E
(at Austin, August 2002.)100.8 332 Q(URL "http://www)5.5 E(.cs.ute)-.715
E(xas.edu/users/gorinsk)-.165 E(y/pubs.html".)-.165 E
([HSTCP] HighSpeed TCP W)100.8 358 Q(eb P)-.88 E(age, URL "http://www)
-.165 E(.icir)-.715 E(.or)-.605 E(g/\215o)-.198 E(yd/hstcp.html".)-.11 E
([J02] Amit Jain and Sally Flo)100.8 384 Q
(yd, "Quick-Start for TCP and IP", internet draft draft-amit-)-.11 E
(quick-start-02.txt, w)100.8 397 Q(ork in progress, 2002.)-.11 E
([K03] T)100.8 423 Q(om K)-.88 E(elly)-.275 E 2.75(,")-.715 G
(Scalable TCP: Impro)-2.75 E(ving Performance in HighSpeed W)-.165 E
(ide Area)-.44 E(Netw)100.8 436 Q(orks", February 2003.)-.11 E
(URL "http://www-lce.eng.cam.ac.uk/~ctk21/scalable/".)5.5 E
([M02] Matt Mathis, "Raising the Internet MTU", W)100.8 462 Q(eb P)-.88
E(age, URL)-.165 E("http://www)100.8 475 Q(.psc.edu/~mathis/MTU/".)-.715
E([Net100] The DOE/MICS Net100 project.)100.8 501 Q(URL)5.5 E
("http://www)100.8 514 Q(.csm.ornl.go)-.715 E(v/~dunig)-.165 E
(an/net100/".)-.055 E([NS] The NS Simulator)100.8 540 Q 2.75(,")-.44 G
(http://www)-2.75 E(.isi.edu/nsnam/ns/".)-.715 E([RFC 1323] V)100.8 566
Q 2.75(.J)-1.419 G
(acobson, R. Braden, and D. Borman, TCP Extensions for High)-2.75 E
(Performance, RFC 1323, May 1992.)100.8 579 Q([RFC3390] Allman, M., Flo)
100.8 605 Q(yd, S., and P)-.11 E(artridge, C., "Increasing TCP')-.165 E
2.75(sI)-.605 G(nitial W)-2.75 E(indo)-.44 E(w",)-.275 E
(RFC 3390, October 2002.)100.8 618 Q([RFC3448] Mark Handle)100.8 644 Q
1.43 -.715(y, J)-.165 H(itendra P).715 E(adh)-.165 E(ye, Sally Flo)-.055
E(yd, and Joer)-.11 E 2.75(gW)-.198 G(idmer)-3.19 E 2.75(,T)-.44 G
(CP Friendly)-2.75 E(Rate Control \(TFRC\): Protocol Speci\214cation, R\
FC 3448, January 2003.)100.8 657 Q([SA03] Souza, E., and Ag)100.8 683 Q
(arw)-.055 E(al, D.A., A HighSpeed TCP Study: Characteristics and)-.11 E
(Deplo)100.8 696 Q(yment Issues, LBNL T)-.11 E
(echnical Report LBNL-53215.)-.77 E(URL)5.5 E("http://www)100.8 709 Q
(.icir)-.715 E(.or)-.605 E(g/\215o)-.198 E(yd/hstcp.html".)-.11 E(Flo)72
769 Q 306.391(yd Section)-.11 F 2.75(17. [P)2.75 F(age 24])-.165 E 0 Cg
EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 66.092(-DRAFT Expires:)-1.012 F
(December 2003)2.75 E(June 2003)116.406 E([S02] Stanisla)100.8 85 Q 2.75
(vS)-.22 G(haluno)-2.75 E 1.43 -.715(v, T)-.165 H
(CP Armonk, draft, 2002, URL).715 E("http://www)100.8 98 Q
(.internet2.edu/~shaluno)-.715 E(v/tcpar/".)-.165 E([S03] Ale)100.8 124
Q 2.75(xS)-.165 G(olan, pri)-2.75 E -.275(va)-.275 G
(te communication, 2003.).275 E([VMSS] "W)100.8 150 Q(eb100 at ORNL", W)
-.88 E(eb P)-.88 E(age,)-.165 E("http://www)100.8 163 Q(.csm.ornl.go)
-.715 E(v/~dunig)-.165 E(an/netperf/web100.html".)-.055 E([W)100.8 189 Q
(eb100] The W)-.88 E(eb100 project.)-.88 E(URL "http://www)5.5 E
(.web100.or)-.715 E(g/".)-.198 E/F1 11/Times-Bold@0 SF(18.)72 228 Q/F2
14/Times-Bold@0 SF(Security Considerations)5.5 E F0(This proposal mak)
100.8 254 Q(es no changes to the underlying security of TCP)-.11 E(.)
-1.221 E F1(19.)72 293 Q F2(IAN)5.5 E 3.5(AC)-.28 G(onsiderations)-3.5 E
F0(There are no IAN)100.8 319 Q 2.75(Ac)-.385 G(onsiderations re)-2.75 E
-.055(ga)-.165 G(rding this document.).055 E F1(20.)72 358 Q F2(TCP')5.5
E 3.5(sL)-.518 G(oss Ev)-3.5 E(ent Rate in Steady-State)-.14 E F0
(This section gi)100.8 384 Q -.165(ve)-.275 G 2.75(st).165 G
(he number of round-trip times between congestion e)-2.75 E -.165(ve)
-.275 G(nts for a TCP).165 E<8d6f>100.8 397 Q 2.75(ww)-.275 G
(ith D-byte pack)-2.75 E
(ets, for D=1500, as a function of the connection')-.11 E 2.75(sa)-.605
G -.165(ve)-2.97 G(rage).165 E(throughput B in bps.)100.8 410 Q 1.76
-.88(To a)5.5 H(chie).88 E .33 -.165(ve t)-.275 H(his a).165 E -.165(ve)
-.22 G(rage throughput B, a TCP connection with round-).165 E
(trip time R in seconds requires an a)100.8 423 Q -.165(ve)-.22 G
(rage congestion windo).165 E 2.75(wwo)-.275 G 2.75(fB)-2.75 G
(R/\(8D\) se)-2.75 E(gments.)-.165 E(In steady-state, TCP')100.8 449 Q
2.75(sa)-.605 G -.165(ve)-2.97 G(rage congestion windo).165 E 2.75(wwi)
-.275 G 2.75(sr)-2.75 G(oughly 1.2/sqrt\(p\) se)-2.75 E 2.75
(gments. This)-.165 F(is equi)100.8 462 Q -.275(va)-.275 G
(lent to a lost e).275 E -.165(ve)-.275 G(nt at most once e).165 E -.165
(ve)-.275 G(ry 1/p pack).165 E(ets, or at most once e)-.11 E -.165(ve)
-.275 G(ry 1/\(pw\) =).165 E(w/1.5 round-trip times.)100.8 475 Q
(Substituting for w)5.5 E 2.75(,t)-.715 G(his is a loss e)-2.75 E -.165
(ve)-.275 G(nt at most e).165 E -.165(ve)-.275 G(ry).165 E
(\(BR\)/12D\)round-trip times.)100.8 488 Q(An an e)100.8 514 Q
(xample, for R = 0.1 seconds and D = 1500 bytes, this gi)-.165 E -.165
(ve)-.275 G 2.75(sB).165 G(/180000 round-trip)-2.75 E
(times between loss e)100.8 527 Q -.165(ve)-.275 G(nts.).165 E 2.75
(B. A)72 553 R(table for a\(w\) and b\(w\).)2.75 E(This section gi)105
579 Q -.165(ve)-.275 G 2.75(sat).165 G
(able for the increase and decrease parameters a\(w\) and b\(w\) for)
-2.75 E(HighSpeed TCP)105 592 Q 2.75(,f)-1.221 G(or the def)-2.75 E
(ault v)-.11 E(alues of Lo)-.275 E(w_W)-.275 E(indo)-.44 E 2.75(w=3)
-.275 G(8, High_W)-2.75 E(indo)-.44 E 2.75(w=8)-.275 G(3000,)-2.75 E
(High_P = 10^-7, and High_Decrease = 0.1.)105 605 Q(Flo)72 769 Q 306.391
(yd Section)-.11 F 2.75(20. [P)2.75 F(age 25])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 66.092(-DRAFT Expires:)-1.012 F
(December 2003)2.75 E(June 2003)116.406 E 5.5(wa)118.75 85 S 2.75
(\(w\) b\(w\))-5.5 F 2.75(---- ---- ----)110.5 98 R 11(38 1)116 111 R
(0.50)5.5 E 11(118 2)113.25 124 R(0.44)5.5 E 11(221 3)113.25 137 R(0.41)
5.5 E 11(347 4)113.25 150 R(0.38)5.5 E 11(495 5)113.25 163 R(0.37)5.5 E
11(663 6)113.25 176 R(0.35)5.5 E 11(851 7)113.25 189 R(0.34)5.5 E 11
(1058 8)110.5 202 R(0.33)5.5 E 11(1284 9)110.5 215 R(0.32)5.5 E 8.25
(1529 10)110.5 228 R(0.31)5.5 E 8.25(1793 11)110.5 241 R(0.30)5.5 E 8.25
(2076 12)110.5 254 R(0.29)5.5 E 8.25(2378 13)110.5 267 R(0.28)5.5 E 8.25
(2699 14)110.5 280 R(0.28)5.5 E 8.25(3039 15)110.5 293 R(0.27)5.5 E 8.25
(3399 16)110.5 306 R(0.27)5.5 E 8.25(3778 17)110.5 319 R(0.26)5.5 E 8.25
(4177 18)110.5 332 R(0.26)5.5 E 8.25(4596 19)110.5 345 R(0.25)5.5 E 8.25
(5036 20)110.5 358 R(0.25)5.5 E 8.25(5497 21)110.5 371 R(0.24)5.5 E 8.25
(5979 22)110.5 384 R(0.24)5.5 E 8.25(6483 23)110.5 397 R(0.23)5.5 E 8.25
(7009 24)110.5 410 R(0.23)5.5 E 8.25(7558 25)110.5 423 R(0.22)5.5 E 8.25
(8130 26)110.5 436 R(0.22)5.5 E 8.25(8726 27)110.5 449 R(0.22)5.5 E 8.25
(9346 28)110.5 462 R(0.21)5.5 E 8.25(9991 29)110.5 475 R(0.21)5.5 E 8.25
(10661 30)107.75 488 R(0.21)5.5 E 8.25(11358 31)107.75 501 R(0.20)5.5 E
8.25(12082 32)107.75 514 R(0.20)5.5 E 8.25(12834 33)107.75 527 R(0.20)
5.5 E 8.25(13614 34)107.75 540 R(0.19)5.5 E 8.25(14424 35)107.75 553 R
(0.19)5.5 E 8.25(15265 36)107.75 566 R(0.19)5.5 E 8.25(16137 37)107.75
579 R(0.19)5.5 E 8.25(17042 38)107.75 592 R(0.18)5.5 E 8.25(17981 39)
107.75 605 R(0.18)5.5 E 8.25(18955 40)107.75 618 R(0.18)5.5 E 8.25
(19965 41)107.75 631 R(0.17)5.5 E 8.25(21013 42)107.75 644 R(0.17)5.5 E
8.25(22101 43)107.75 657 R(0.17)5.5 E 8.25(23230 44)107.75 670 R(0.17)
5.5 E 8.25(24402 45)107.75 683 R(0.16)5.5 E 8.25(25618 46)107.75 696 R
(0.16)5.5 E 8.25(26881 47)107.75 709 R(0.16)5.5 E 8.25(28193 48)107.75
722 R(0.16)5.5 E(Flo)72 769 Q 306.391(yd Section)-.11 F 2.75(20. [P)2.75
F(age 26])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 66.092(-DRAFT Expires:)-1.012 F
(December 2003)2.75 E(June 2003)116.406 E 8.25(29557 49)107.75 85 R
(0.15)5.5 E 8.25(30975 50)107.75 98 R(0.15)5.5 E 8.25(32450 51)107.75
111 R(0.15)5.5 E 8.25(33986 52)107.75 124 R(0.15)5.5 E 8.25(35586 53)
107.75 137 R(0.14)5.5 E 8.25(37253 54)107.75 150 R(0.14)5.5 E 8.25
(38992 55)107.75 163 R(0.14)5.5 E 8.25(40808 56)107.75 176 R(0.14)5.5 E
8.25(42707 57)107.75 189 R(0.13)5.5 E 8.25(44694 58)107.75 202 R(0.13)
5.5 E 8.25(46776 59)107.75 215 R(0.13)5.5 E 8.25(48961 60)107.75 228 R
(0.13)5.5 E 8.25(51258 61)107.75 241 R(0.13)5.5 E 8.25(53677 62)107.75
254 R(0.12)5.5 E 8.25(56230 63)107.75 267 R(0.12)5.5 E 8.25(58932 64)
107.75 280 R(0.12)5.5 E 8.25(61799 65)107.75 293 R(0.12)5.5 E 8.25
(64851 66)107.75 306 R(0.11)5.5 E 8.25(68113 67)107.75 319 R(0.11)5.5 E
8.25(71617 68)107.75 332 R(0.11)5.5 E 8.25(75401 69)107.75 345 R(0.10)
5.5 E 8.25(79517 70)107.75 358 R(0.10)5.5 E 8.25(84035 71)107.75 371 R
(0.10)5.5 E 8.25(89053 72)107.75 384 R(0.10)5.5 E 8.25(94717 73)107.75
397 R(0.09)5.5 E -.88(Ta)105 423 S(ble 12: P).88 E
(arameters for HighSpeed TCP)-.165 E(.)-1.221 E(This table w)105 449 Q
(as computed with the follo)-.11 E(wing Perl program:)-.275 E(Flo)72 769
Q 306.391(yd Section)-.11 F 2.75(20. [P)2.75 F(age 27])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 66.092(-DRAFT Expires:)-1.012 F
(December 2003)2.75 E(June 2003)116.406 E($top = 100000;)107.75 85 Q
($num = 38;)107.75 98 Q(if \($num == 38\) {)107.75 111 Q(print ")113.25
124 Q 5.5(wa)13.75 G 2.75(\(w\) b\(w\)\\n";)-5.5 F(print ")113.25 137 Q
2.75(---- ---- ----\\n";)5.5 F(print ")113.25 150 Q 11(38 1)11 F
(0.50\\n";)5.5 E($oldb = 0.50;)113.25 163 Q($olda = 1;)113.25 176 Q(})
107.75 189 Q(while \($num < $top\) {)107.75 202 Q($bw = \(0.1 -0.5\)*\(\
log\($num\)-log\(38\)\)/\(log\(83000\)-log\(38\)\)+0.5;)113.25 215 Q($a)
113.25 228 Q 2.75(w=\()-.165 G
($num**2*2.0*$bw\) / \(\(2.0-$bw\)*$num**1.2*12.8\);)-2.75 E(if \($a)
113.25 241 Q 2.75(w>$)-.165 G(olda + 1\) {)-2.75 E(printf "%6d %5d)121.5
254 Q(%3.2f0, $num, $a)5.5 E 1.43 -.715(w, $)-.165 H(bw;).715 E
($olda = $a)121.5 267 Q(w;)-.165 E(})113.25 280 Q($num ++;)113.25 293 Q
(})107.75 306 Q -.88(Ta)105 332 S
(ble 13: Perl Program for computing parameters for HighSpeed TCP).88 E
(.)-1.221 E 2.75(C. Exploring)72 358 R(the time to con)2.75 E -.165(ve)
-.44 G -.198(rg).165 G 2.75(et).198 G 2.75(of)-2.75 G(airness.)-2.86 E
(This section gi)105 384 Q -.165(ve)-.275 G 2.75(st).165 G
(he Perl program used to compute the congestion windo)-2.75 E 2.75(wg)
-.275 G(ro)-2.75 E(wth)-.275 E(during congestion a)105 397 Q -.22(vo)
-.22 G(idance.).22 E(Flo)72 769 Q 306.391(yd Section)-.11 F 2.75(20. [P)
2.75 F(age 28])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 66.092(-DRAFT Expires:)-1.012 F
(December 2003)2.75 E(June 2003)116.406 E($top = 2001;)107.75 85 Q
($hswin = 1;)107.75 98 Q($re)107.75 111 Q(gwin = 1;)-.165 E($rtt = 1;)
107.75 124 Q($lastrtt = 0;)107.75 137 Q($rttstep = 100;)107.75 150 Q
(if \($hswin == 1\) {)107.75 163 Q(print ")113.25 176 Q -.66(RT)5.5 G
5.5(TH).66 G(S_W)-5.5 E(indo)-.44 E 2.75(wS)-.275 G(tandard_TCP_W)-2.75
E(indo)-.44 E(w0;)-.275 E(print ")113.25 189 Q 2.75(--- ---------)5.5 F
(-------------------0;)2.75 E(})107.75 202 Q(while \($rtt < $top\) {)
107.75 215 Q($bw = \(0.1 -0.5\)*\(log\($hswin\)-log\(38\)\)/\(log\(8300\
0\)-log\(38\)\)+0.5;)113.25 228 Q($a)113.25 241 Q 2.75(w=\()-.165 G
($hswin**2*2.0*$bw\) / \(\(2.0-$bw\)*$hswin**1.2*12.8\);)-2.75 E
(if \($a)113.25 254 Q 2.75(w<1)-.165 G 2.75(\){)-2.75 G($a)124.25 267 Q
2.75(w=1)-.165 G(;)-2.75 E(})113.25 280 Q
(if \($rtt >= $lastrtt + $rttstep\) {)113.25 293 Q
(printf "%5d %9d %10d0, $rtt, $hswin, $re)118.75 306 Q(gwin;)-.165 E
($lastrtt = $rtt;)118.75 319 Q(})113.25 332 Q($hswin += $a)113.25 345 Q
(w;)-.165 E($re)113.25 358 Q(gwin += 1;)-.165 E($rtt ++;)113.25 371 Q(})
107.75 384 Q -.88(Ta)105 410 S
(ble 14: Perl Program for computing the windo).88 E 2.75(wi)-.275 G 2.75
(nc)-2.75 G(ongestion a)-2.75 E -.22(vo)-.22 G(idance.).22 E -.605(AU)
105 436 S(THORS' ADDRESSES).605 E(Sally Flo)138 475 Q(yd)-.11 E
(Phone: +1 \(510\) 666-2989)138 488 Q
(ICIR \(ICSI Center for Internet Research\))138 501 Q(Email: \215o)138
514 Q(yd@icir)-.11 E(.or)-.605 E(g)-.198 E(URL: http://www)138 527 Q
(.icir)-.715 E(.or)-.605 E(g/\215o)-.198 E(yd/)-.11 E(This draft w)138
553 Q(as created in August 2002.)-.11 E(Flo)72 769 Q 306.391(yd Section)
-.11 F 2.75(20. [P)2.75 F(age 29])-.165 E 0 Cg EP
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