One document matched: draft-ietf-tsvwg-quickstart-07.ps

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/F0 10/Courier-Bold@0 SF(Internet Engineering Task Force)72 85 Q
(S. Floyd)197.998 E 287.998(INTERNET-DRAFT M.)72 98 R(Allman)6 E 203.998
(draft-ietf-tsvwg-quickstart-07.ps ICIR)72 111 R(Expires: April 2007)72
124 Q(A. Jain)275.998 E(F5 Networks)437.998 137 Q(P. Sarolahti)431.998
150 Q(Nokia Research Center)377.998 163 Q 6(9O)419.998 176 S
(ctober 2006)-6 E/F1 14/Times-Bold@0 SF(Quick-Start f)204.175 214 Q
(or TCP and IP)-.35 E/F2 11/Times-Bold@0 SF(Status of this Memo)72 246 Q
/F3 11/Times-Roman@0 SF
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(Internet-Drafts are draft documents v)100.8 347.8 Q
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F2(Abstract)72 475.6 Q F3(This document speci\214es an optional Quick-S\
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(cooperation with routers, to determine an allo)100.8 514.6 Q
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(the middle of a data transfer \(e.g., after an idle period\).)100.8
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100.8 631.6 Q(These paths also include paths with routers or middlebox)
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(bout the role of TCP feedback.)-2.75 E 2.75(-U)109.05 176 S
(pdated the \215o)-2.75 E 2.75(wl)-.275 G
(abel discussion from RFC2460 to RFC3697.)-2.75 E 2.75(-I)109.05 189 S
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(end-point address changes in Section 4.1.)114.55 293 Q
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(Lars Eggert.)109.05 358 Q
(This includes changing one "should" to "SHOULD",)109.05 371 Q
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(response to AD Feedback from Lars Eggert.)109.05 501 Q 2.75(*D)103.55
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(From AD feedback about deleting unnecessary)109.05 540 Q(appendices.)
109.05 553 Q 2.75(*A)103.55 579 S
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(sections contain normati)109.05 592 Q .33 -.165(ve r)-.275 H
(eferences, and which).165 E(sections are general discussion.)109.05 605
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(from Dan Romascanu.)109.05 98 Q 2.75(*R)100.8 124 S(ephrased be)-2.75 E
(ginning of second paragraph in the)-.165 E 2.75(Abstract. From)106.3
137 R(feedback from James Polk.)2.75 E
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103.55 189 S(dded a discussion of the lo)-2.75 E
(wer limit of the rate request)-.275 E
(of 80 kbps, from feedback from Gorry F)109.05 202 Q(airhurst.)-.165 E
2.75(*A)103.55 228 S(dded the QS Nonce to the QS Appro)-2.75 E -.165(ve)
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241 Q(airhurst.)-.165 E 2.75(*M)103.55 267 S -.165(ove)-2.75 G 2.75(dt)
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(From feedback from Gorry F)109.05 280 Q(airhurst.)-.165 E
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(Quick-Start Request, it MUST start using it within one)109.05 618 Q
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(-than-best-ef)-.22 E(fort service.)-.275 E 2.75(*A)103.55 631 S
(dded a fe)-2.75 E 2.75(ws)-.275 G(entences about the requirements for)
-2.75 E(randomness in the nonce.)109.05 644 Q 2.75(*C)103.55 657 S
(hanged the name of the option from the Quick-Start Request)-2.75 E
(Option to the Quick-Start Option.)109.05 670 Q 2.75(*C)103.55 683 S
(hanged the semantics of the Reserv)-2.75 E(ed \214eld to the Function)
-.165 E(\214eld, adding that a Quick-Start option is only interpreted)
109.05 696 Q(as a request if this \214eld is zero.)109.05 709 Q 2.75(*C)
103.55 722 S(hanged the "Reporting Appro)-2.75 E -.165(ve)-.165 G 2.75
(dR).165 G(ate" option from a)-2.75 E(Flo)72 769 Q 267.275
(yd/Allman/Jain/Sarolahti [P)-.11 F(age 5])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
("Possible Use" in Appendix to a required use in Section 3.1,)109.05 85
Q(to allo)109.05 98 Q 2.75(wr)-.275 G(outers and recei)-2.75 E -.165(ve)
-.275 G(rs some protection ag).165 E(ainst)-.055 E(misbeha)109.05 111 Q
(ving senders.)-.22 E 2.75(*C)103.55 124 S
(hanges from feedback from Bob Briscoe:)-2.75 E 2.75(-A)109.05 137 S
(dded Appendix about Sections 1-3 of)-2.75 E(Bob Briscoe')114.55 150 Q
2.75(sd)-.605 G(ocument.)-2.75 E 2.75(-A)109.05 163 S
(dded a clari\214cation that the appro)-2.75 E -.275(va)-.165 G 2.75(lo)
.275 G 2.75(fa)-2.75 G(Quick-Start request at a router does not af)
114.55 176 Q(fect)-.275 E(the treatment of the subsequent arri)114.55
189 Q(ving)-.275 E(Quick-Start data pack)114.55 202 Q(ets.)-.11 E 2.75
(-A)109.05 215 S(dded the one-w)-2.75 E
(ay hash function as an alternate)-.11 E
(implementation for the QS Nonce.)114.55 228 Q 2.75(-C)109.05 241 S
(lari\214ed the phrase "incrementally deplo)-2.75 E(yable", adding)-.11
E(the follo)114.55 254 Q(wing:)-.275 E("W)114.55 267 Q 2.75(en)-.88 G
(ote that while Quick-Start is incrementally deplo)-2.75 E(yable)-.11 E
(in this sense, a Quick-Start request cannot be appro)114.55 280 Q -.165
(ve)-.165 G(d).165 E
(for a particular connection unless both end-nodes and all)114.55 293 Q
(of the routers along the path ha)114.55 306 Q .33 -.165(ve b)-.22 H
(een con\214gured to).165 E(support Quick-Start.")114.55 319 Q 2.75(-C)
109.05 332 S(lari\214ed semantics about additional rate.)-2.75 E 2.75
(-S)109.05 345 S(aid that when den)-2.75 E
(ying a rate request, the router)-.165 E
(may in the future use the QS Nonce \214eld to report)114.55 358 Q
(an error code.)114.55 371 Q 2.75(-A)109.05 384 S(dd Bob')-2.75 E 2.75
(ss)-.605 G(uggestion from Section 4.4 as an alternate)-2.75 E
(possible rate encoding.)114.55 397 Q 2.75(-M)109.05 410 S
(ade changes suggested in Section 5.1.3 of Bob')-2.75 E 2.75(sp)-.605 G
(aper)-2.75 E(,)-.44 E
(including saying that the router should decrement the QS TTL)114.55 423
Q(by the same amount that it decrements the IP TTL \(on the)114.55 436 Q
(of)114.55 449 Q 2.75(fc)-.275 G
(hance that it decrements the IP TTL by more than one\).)-2.75 E 2.75
(-F)109.05 462 S(ix)-2.75 E(ed nits.)-.165 E
(Changes from draft-ietf-tsvwg-quickstart-00:)103.55 488 Q 2.75(*A)
103.55 501 S(dded a 30-bit QS Nonce.)-2.75 E
(Based on feedback from Guohan Lu)5.5 E(and Gorry F)109.05 514 Q
(airhurst \(and deleted the te)-.165 E(xt about a possible)-.165 E(four)
109.05 527 Q(-bit QS nonce\).)-.22 E 2.75(*A)103.55 540 S(dded a ne)
-2.75 E 2.75(ws)-.275 G
(ection "Quick-Start and IPsec AH", based on feedback)-2.75 E
(from Joe T)114.55 553 Q(ouch and Da)-.88 E(vid Black.)-.22 E 2.75(*R)
103.55 566 S -.275(ev)-2.75 G(ised "Quick-Start in IP T).275 E
(unnels" Section, based on feedback)-.495 E(from Joe T)109.05 579 Q
(ouch and Da)-.88 E(vid Black.)-.22 E 2.75(*A)103.55 592 S
(dded a section about "Possible Uses for the Reserv)-2.75 E(ed Fields".)
-.165 E 2.75(*C)103.55 605 S(hanges from feedback from Gorry F)-2.75 E
(airhurst:)-.165 E 2.75(-S)109.05 618 S(ection 4.4, re)-2.75 E
(vised the e)-.275 E(xplanation for reducing the)-.165 E
(congestion windo)114.55 631 Q 2.75(ww)-.275 G(hen the \214rst A)-2.75 E
(CK for a Quick-Start)-.44 E(pack)114.55 644 Q(et is recei)-.11 E -.165
(ve)-.275 G(d.).165 E 2.75(-S)109.05 657 S
(ection 6.4, deleted the last sentence.)-2.75 E 2.75(-M)109.05 670 S
(inor editing changes.)-2.75 E 2.75(-R)109.05 683 S -.275(ev)-2.75 G
(ised Section 4.6.2 to say that sender SHOULD send one pack).275 E(et)
-.11 E(with an initial R)114.55 696 Q .396 -.198(TO o)-.66 H 2.75(ft)
.198 G(hree seconds.)-2.75 E 2.75(-R)109.05 709 S -.275(ev)-2.75 G
(ised Section 4.6.3 to say that the TCP sender SHOULD use an).275 E
(initial R)114.55 722 Q .396 -.198(TO s)-.66 H(etting of three seconds.)
.198 E(Flo)72 769 Q 267.275(yd/Allman/Jain/Sarolahti [P)-.11 F(age 6])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E 2.75(-A)109.05 85 S(dded te)
-2.75 E(xt to Section 6.2 on Multiple P)-.165 E(aths, discussing)-.165 E
(multipath routing.)120.05 98 Q 2.75(-C)109.05 111 S
(lari\214ed about GPRS round-trip times.)-2.75 E 2.75(-C)109.05 124 S
(lari\214ed about PMTUD and the \214rst windo)-2.75 E 2.75(wo)-.275 G
2.75(fd)-2.75 G(ata.)-2.75 E 2.75(-As)109.05 137 S(mall reor)-2.75 E
-.055(ga)-.198 G(nization, rearranging sections.).055 E 2.75(*C)103.55
150 S(hanges from feedback from Martin Duk)-2.75 E(e:)-.11 E 2.75(-R)
109.05 163 S -.275(ev)-2.75 G(ised te).275 E
(xt about the size of QS requests.)-.165 E 2.75(-A)109.05 176 S
(dded some te)-2.75 E
(xt to Section 4.1, about when to send QS requests.)-.165 E
(Changes from draft-amit-quick-start-04.txt:)103.55 202 Q 2.75(*As)
103.55 215 S(igni\214cant amount of general editing.)-2.75 E 2.75(*B)
103.55 228 S
(ecause the Rate Request \214eld only uses four bits, speci\214ed)-2.75
E(that the other four bits are reserv)109.05 241 Q(ed, and talk)-.165 E
(ed about a)-.11 E(possible use for them.)109.05 254 Q
(This is discussed in a ne)5.5 E 2.75(ws)-.275 G(ection on)-2.75 E
("A Rate-Reduced Nonce?")109.05 267 Q 2.75(*S)103.55 280 S
(peci\214ed that a Quick-Start-capable router den)-2.75 E
(ying a request)-.165 E
(SHOULD delete the Quick-Start option, and if this is not)109.05 293 Q
(possible, SHOULD zero the QS TTL and the Rate Request \214elds.)109.05
306 Q 2.75(*M)103.55 319 S(ade the follo)-2.75 E(wing change:)-.275 E
(If the Quick-Start Response is lost)5.5 E(in the netw)109.05 332 Q
(ork, it is not retransmitted.)-.11 E 2.75(*F)103.55 345 S
(or PMTUD, in Section 4.6, added a suggestion to send one lar)-2.915 E
(ge)-.198 E(pack)109.05 358 Q(et in the initial windo)-.11 E 2.75(wf)
-.275 G(or PMTUD, and to send the other)-2.75 E(pack)109.05 371 Q
(ets at 576 bytes.)-.11 E 2.75(*A)103.55 384 S
(dded a paragraph to Section 4.6.3 on retransmitted SYN pack)-2.75 E
(ets,)-.11 E(saying the)109.05 397 Q 2.75(ys)-.165 G(hould use an R)
-2.75 E .396 -.198(TO o)-.66 H 2.75(ft).198 G(hree seconds and a ne)
-2.75 E 2.75(wI)-.275 G(SN)-2.75 E(on the retransmitted SYN pack)109.05
410 Q(et.)-.11 E 2.75(*A)103.55 423 S(dded that "TCP SHOULD NO)-2.75 E
2.75(Tu)-.44 G(se Quick-Start" after an)-2.75 E
(application-limited period at this time, in Section 4.1, in)109.05 436
Q(addition to the old sentence that this "requires further thought)
109.05 449 Q(and in)109.05 462 Q -.165(ve)-.44 G(stig).165 E(ation".)
-.055 E 2.75(*A)103.55 475 S
(dded an appendix on "Possible Router Algorithm".)-2.75 E 2.75(*M)103.55
488 S -.165(ove)-2.75 G 2.75(dt).165 G
(he section on "Quick-Start with DCCP" to the appendix.)-2.75 E 2.75(*N)
103.55 501 S(ame changed from draft-amit-quick-start-04.txt to)-2.75 E
(draft-tsvwg-quickstart-00.txt.)109.05 514 Q
(Changes from draft-amit-quick-start-03.txt:)103.55 540 Q 2.75(*A)103.55
553 S(dded a citation to the paper on "Ev)-2.75 E
(aluating Quick-Start for)-.275 E(TCP", and added pointers to the w)
109.05 566 Q(ork in that paper)-.11 E(.)-.605 E(This w)109.05 579 Q
(ork includes:)-.11 E 2.75(-D)109.05 592 S
(iscussions of router algorithms.)-2.75 E 2.75(-D)109.05 605 S
(iscussions of sizing Quick-Start requests.)-2.75 E 2.75(*A)103.55 618 S
(dded sections on "Misbeha)-2.75 E(ving Middlebox)-.22 E
(es", and on "Attacks on)-.165 E(Quick-Start".)109.05 631 Q
(Changes from draft-amit-quick-start-02.txt:)103.55 657 Q 2.75(*A)103.55
670 S(dded a discussion on Using Quick-Start in the Middle of a)-2.75 E
2.75(Connection. The)109.05 683 R(request w)2.75 E
(ould be on the total rate,)-.11 E(not on the additional rate.)109.05
696 Q 2.75(*C)103.55 709 S
(hanged name "Initial Rate" to "Rate Request", and changed)-2.75 E
(the units from pack)109.05 722 Q(ets per second to bytes per second.)
-.11 E(Flo)72 769 Q 267.275(yd/Allman/Jain/Sarolahti [P)-.11 F(age 7])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E 2.75(*T)103.55 85 S(he follo)
-2.75 E(wing sections are ne)-.275 E(w:)-.275 E 2.75(-T)109.05 98 S
(he Quick-Start Request Option for IPv6)-2.75 E 2.75(-Q)109.05 111 S
(uick-Start in IP T)-2.75 E(unnels)-.495 E 2.75(-W)109.05 124 S
(hen to Use Quick-Start)-2.75 E 2.75(-T)109.05 137 S
(CP: Responding to a Loss of a Quick-Start P)-2.75 E(ack)-.165 E(et)-.11
E 2.75(-T)109.05 150 S(CP: A Quick-Start Request for a Lar)-2.75 E
(ger Initial W)-.198 E(indo)-.44 E(w)-.275 E 2.75(-T)109.05 163 S
(CP: A Quick-Start Request after an Idle Period)-2.75 E 2.75(-T)109.05
176 S(he Quick-Start Mechanisms in DCCP and other T)-2.75 E(ransport)
-.385 E(Protocols)114.55 189 Q 2.75(-Q)109.05 202 S
(uick-Start with DCCP)-2.75 E 2.75(-I)109.05 215 S
(mplementation and Deplo)-2.75 E(yment Issues)-.11 E 2.75(-D)109.05 228
S(esign Decisions)-2.75 E 2.75(*A)103.55 241 S(dded a discussion of K)
-2.75 E(unniyur')-.165 E 2.75(sA)-.605 G(nti-ECN proposal.)-2.75 E 2.75
(*A)103.55 254 S
(dded a section on simulations, with a brief discussion of the)-2.75 E
(simulations by Srikanth Sundarrajan.)109.05 267 Q
(Changes from draft-amit-quick-start-01.txt:)103.55 293 Q 2.75(*A)103.55
306 S(dded a discussion in the related w)-2.75 E(ork section about the)
-.11 E(possibility of optimistically sending a lar)109.05 319 Q
(ge initial windo)-.198 E -.715(w,)-.275 G(without e)109.05 332 Q
(xplicit permission of routers.)-.165 E 2.75(*A)103.55 345 S
(dded a discussion in the related w)-2.75 E(ork section about the)-.11 E
(tradeof)109.05 358 Q(fs of XCP vs. Quick-Start.)-.275 E 2.75(*A)103.55
371 S(dded a section on "The Quick-Start Request: P)-2.75 E(ack)-.165 E
(ets or Bytes?")-.11 E(Changes from draft-amit-quick-start-00.txt:)
103.55 397 Q 2.75(*T)103.55 410 S(he addition of a citation to [KHR02].)
-2.75 E 2.75(*T)103.55 423 S(he addition of a Related W)-2.75 E
(ork section.)-.88 E 2.75(*D)103.55 436 S(eleted the QS Nonce, in f)
-2.75 E -.22(avo)-.11 G 2.75(ro).22 G 2.75(far)-2.75 G(andom initial v)
-2.75 E(alue for the)-.275 E(QS TTL.)109.05 449 Q(Flo)72 769 Q 267.275
(yd/Allman/Jain/Sarolahti [P)-.11 F(age 8])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E/F1 13/Times-Bold@0 SF -1.196
(Ta)253.526 85 S(ble of Contents)1.196 E/F2 10/Times-Roman@0 SF
(1. Introduction)100.8 110 Q F0 11(.......................)11.01 G F2
(11)6.5 E(1.1. Con)115.8 122 Q -.15(ve)-.4 G(ntions and T).15 E
(erminology)-.7 E F0 11(................)13.23 G F2(12)6.5 E
(2. Assumptions and General Principles)100.8 134 Q F0 11
(................)10.88 G F2(12)6.5 E(2.1. Ov)115.8 146 Q(ervie)-.15 E
2.5(wo)-.25 G 2.5(fQ)-2.5 G(uick-Start)-2.5 E F0 11(..................)
7.68 G F2(13)6.5 E(3. The Quick-Start Option in IP)100.8 158 Q F0 11
(..................)12.54 G F2(15)6.5 E
(3.1. The Quick-Start Option for IPv4)115.8 170 Q F0 11
(................)3.66 G F2(15)6.5 E
(3.2. The Quick-Start Option for IPv6)115.8 182 Q F0 11
(................)3.66 G F2(18)6.5 E
(3.3. Processing the Quick-Start Request at Routers)115.8 194 Q F0 11
(............)3.94 G F2(19)6.5 E(3.3.1. Processing the Report of Appro)
130.8 206 Q -.15(ve)-.15 G 2.5(dR).15 G(ate)-2.5 E F0 11(............)
5.08 G F2(20)6.5 E(3.4. The QS Nonce)115.8 218 Q F0 11
(.....................)6.02 G F2(20)6.5 E
(4. The Quick-Start Mechanisms in TCP)100.8 230 Q F0 11
(................)7.82 G F2(22)6.5 E
(4.1. Sending the Quick-Start Request)115.8 242 Q F0 11
(................)2.82 G F2(23)6.5 E
(4.2. The Quick-Start Response Option in the TCP header)115.8 254 Q F0
11(..........)5.89 G F2(24)6.5 E
(4.3. TCP: Sending the Quick-Start Response)115.8 266 Q F0 11
(..............).59 G F2(25)6.5 E(4.4. TCP: Recei)115.8 278 Q
(ving and Using the Quick-Start Response P)-.25 E(ack)-.15 E(et)-.1 E F0
11(........)3.33 G F2(25)6.5 E(4.5. TCP: Controlling Ackno)115.8 290 Q
(wledgement T)-.25 E(raf)-.35 E(\214c on the Re)-.25 E -.15(ve)-.25 G
(rse P).15 E(ath)-.15 E F0 11(......)13.4 G F2(27)6.5 E
(4.6. TCP: Responding to a Loss of a Quick-Start P)115.8 302 Q(ack)-.15
E(et)-.1 E F0 11(..........)10.85 G F2(28)6.5 E
(4.7. TCP: A Quick-Start Request for a Lar)115.8 314 Q(ger Initial W)
-.18 E(indo)-.4 E(w)-.25 E F0 11(.........)2.98 G F2(29)6.5 E
(4.7.1. Interactions with P)130.8 326 Q(ath MTU Disco)-.15 E -.15(ve)
-.15 G(ry).15 E F0 11(............)11.06 G F2(29)6.5 E
(4.7.2. Quick-Start Request P)130.8 338 Q(ack)-.15 E
(ets that are Discarded by Routers or Middlebox)-.1 E(es)-.15 E F0 11
(..)3.26 G F2(29)6.5 E
(4.8. TCP: A Quick-Start Request in the Middle of a Connection)115.8 350
Q F0 11(........)6.71 G F2(30)6.5 E
(4.9. An Example Quick-Start Scenario with TCP)115.8 362 Q F0 11
(............)11.16 G F2(31)6.5 E(5. Quick-Start and IPsec AH)100.8 374
Q F0 11(...................)10.75 G F2(31)6.5 E(6. Quick-Start in IP T)
100.8 386 Q(unnels and MPLS)-.45 E F0 11(................)8.54 G F2(32)
6.5 E(6.1. Simple T)115.8 398 Q
(unnels That Are Compatible with Quick-Start)-.45 E F0 11(.........)
10.91 G F2(34)6.5 E(6.1.1. Simple T)130.8 410 Q(unnels that are A)-.45 E
-.1(wa)-.92 G(re of Quick-Start).1 E F0 11(..........)11.26 G F2(34)6.5
E(6.2. Simple T)115.8 422 Q
(unnels That Are Not Compatible with Quick-Start)-.45 E F0 11(........)
7.16 G F2(34)6.5 E(6.3. T)115.8 434 Q(unnels That Support Quick-Start)
-.45 E F0 11(...............)12.02 G F2(35)6.5 E
(6.4. Quick-Start and MPLS)115.8 446 Q F0 11(...................).73 G
F2(36)6.5 E(7. The Quick-Start Mechanism in other T)100.8 458 Q
(ransport Protocols)-.35 E F0 11(..........)10.69 G F2(36)6.5 E
(8. Using Quick-Start)100.8 470 Q F0 11(......................)1.15 G F2
(37)6.5 E(8.1. Determining the Rate to Request)115.8 482 Q F0 11
(................)3.1 G F2(37)6.5 E
(8.2. Deciding the Permitted Rate Request at a Router)115.8 494 Q F0 11
(...........)8.25 G F2(37)6.5 E(9. Ev)100.8 506 Q
(aluation of Quick-Start)-.25 E F0 11(...................)12.38 G F2(38)
6.5 E(9.1. Bene\214ts of Quick-Start)115.8 518 Q F0 11
(...................).18 G F2(38)6.5 E(9.2. Costs of Quick-Start)115.8
530 Q F0 11(...................)10.73 G F2(39)6.5 E
(9.3. Quick-Start with QoS-enabled T)115.8 542 Q(raf)-.35 E<8c63>-.25 E
F0 11(..............)10.94 G F2(40)6.5 E(9.4. Protection ag)115.8 554 Q
(ainst Misbeha)-.05 E(ving Nodes)-.2 E F0 11(..............)7.24 G F2
(40)6.5 E(9.4.1. Misbeha)130.8 566 Q(ving Senders)-.2 E F0 11
(.................)11.77 G F2(40)6.5 E(9.4.2. Recei)130.8 578 Q -.15(ve)
-.25 G(rs L).15 E(ying about Whether the Request w)-.55 E(as Appro)-.1 E
-.15(ve)-.15 G(d).15 E F0 11(......)13.1 G F2(41)6.5 E(9.4.3. Recei)
130.8 590 Q -.15(ve)-.25 G(rs L).15 E(ying about the Appro)-.55 E -.15
(ve)-.15 G 2.5(dR).15 G(ate)-2.5 E F0 11(...........)13.12 G F2(42)6.5 E
(9.4.4. Collusion between Misbeha)130.8 602 Q(ving Routers)-.2 E F0 11
(............)3.85 G F2(43)6.5 E(9.5. Misbeha)115.8 614 Q
(ving Middlebox)-.2 E(es and the IP TTL)-.15 E F0 11(.............)4.98
G F2(44)6.5 E(9.6. Attacks on Quick-Start)115.8 626 Q F0 11
(...................).74 G F2(44)6.5 E
(9.7. Simulations with Quick-Start)115.8 638 Q F0 11(.................)
3.22 G F2(45)6.5 E(10. Implementation and Deplo)100.8 650 Q
(yment Issues)-.1 E F0 11(...............)6.4 G F2(45)6.5 E
(10.1. Implementation Issues for Sending Quick-Start Requests)115.8 662
Q F0 11(........)11.72 G F2(45)6.5 E
(10.2. Implementation Issues for Processing Quick-Start Requests)115.8
674 Q F0 11(........)1.17 G F2(45)6.5 E(10.3. Possible Deplo)115.8 686 Q
(yment Scenarios)-.1 E F0 11(................)2.64 G F2(46)6.5 E
(10.4. A Comparison with the Deplo)115.8 698 Q(yment Problems of ECN)-.1
E F0 11(.........)6.39 G F2(47)6.5 E(11. Security Considerations)100.8
710 Q F0 11(....................).87 G F2(47)6.5 E(12. IAN)100.8 722 Q
2.5(AC)-.35 G(onsiderations)-2.5 E F0 11(....................)9.56 G F2
(48)6.5 E F0(Flo)72 769 Q 267.275(yd/Allman/Jain/Sarolahti [P)-.11 F
(age 9])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E/F1 10/Times-Roman@0 SF
(12.1. IP Option)115.8 84 Q F0 11(......................)7.53 G F1(48)
6.5 E(12.2. TCP Option)115.8 96 Q F0 11(.....................)11.83 G F1
(49)6.5 E(13. Conclusions)100.8 108 Q F0 11(.......................)6 G
F1(49)6.5 E(14. Ackno)100.8 120 Q(wledgements)-.25 E F0 11
(.....................)3.77 G F1(49)6.5 E(A. Related W)100.8 132 Q(ork)
-.8 E F0 11(.......................)3.21 G F1(50)6.5 E(A.1. F)115.8 144
Q(ast Start-ups without Explicit Information from Routers)-.15 E F0 11
(.........).05 G F1(50)6.5 E
(A.2. Optimistic Sending without Explicit Information from Routers)115.8
156 Q F0 11(.......)5.17 G F1(51)6.5 E(A.3. F)115.8 168 Q
(ast Start-ups with other Information from Routers)-.15 E F0 11
(..........)10.2 G F1(52)6.5 E(A.4. F)115.8 180 Q
(ast Start-ups with more Fine-Grained Feedback from Routers)-.15 E F0 11
(.......)5.08 G F1(53)6.5 E(A.5. F)115.8 192 Q(ast Start-ups with Lo)
-.15 E(wer)-.25 E(-Than-Best-Ef)-.2 E(fort Service)-.25 E F0 11
(..........)6.48 G F1(53)6.5 E(B. Design Decisions)100.8 204 Q F0 11
(......................)2.26 G F1(54)6.5 E
(B.1. Alternate Mechanisms for the Quick-Start Request: ICMP and RSVP)
115.8 216 Q F0 11(.....)6.58 G F1(54)6.5 E(B.1.1. ICMP)130.8 228 Q F0 11
(......................)3.08 G F1(54)6.5 E(B.1.2. RSVP)130.8 240 Q F0 11
(......................)2.52 G F1(55)6.5 E
(B.2. Alternate Encoding Functions)115.8 252 Q F0 11(................)
12.54 G F1(56)6.5 E(B.3. The Quick-Start Request: P)115.8 264 Q(ack)-.15
E(ets or Bytes?)-.1 E F0 11(............)11.97 G F1(57)6.5 E
(B.4. Quick-Start Semantics: T)115.8 276 Q
(otal Rate or Additional Rate?)-.8 E F0 11(.........)10.71 G F1(58)6.5 E
(B.5. Alternate Responses to the Loss of a Quick-Start P)115.8 288 Q
(ack)-.15 E(et)-.1 E F0 11(.........)4.62 G F1(59)6.5 E(B.6. Wh)115.8
300 Q 2.5(yN)-.05 G(ot Include More Functionality?)-2.5 E F0 11
(..............)6.21 G F1(59)6.5 E
(B.7. Alternate Implementations for a Quick-Start Nonce)115.8 312 Q F0
11(..........)9.24 G F1(62)6.5 E
(B.7.1. An Alternate Proposal for the Quick-Start Nonce)130.8 324 Q F0
11(.........)10.21 G F1(62)6.5 E(B.7.2. The Earlier Request-Appro)130.8
336 Q -.15(ve)-.15 G 2.5(dQ).15 G(uick-Start Nonce)-2.5 E F0 11
(.........)5.52 G F1(63)6.5 E(C. Quick-Start with DCCP)100.8 348 Q F0 11
(....................)4.47 G F1(63)6.5 E(D. Possible Router Algorithm)
100.8 360 Q F0 11(...................)6 G F1(65)6.5 E
(E. Possible Additional Uses for the Quick-Start Option)100.8 372 Q F0
11(............)1.71 G F1(66)6.5 E(Normati)100.8 384 Q .3 -.15(ve R)-.25
H(eferences).15 E F0 11(.....................)8.66 G F1(67)6.5 E
(Informati)100.8 396 Q .3 -.15(ve R)-.25 H(eferences).15 E F0 11
(.....................)4.22 G F1(67)6.5 E -.55(AU)100.8 408 S
(THORS' ADDRESSES).55 E F0 11(....................)1.97 G F1(72)6.5 E
(Full Cop)100.8 420 Q(yright Statement)-.1 E F0 11(....................)
10.12 G F1(73)6.5 E(Intellectual Property)100.8 432 Q F0 11
(......................)2.27 G F1(73)6.5 E F0(Flo)72 769 Q 261.775
(yd/Allman/Jain/Sarolahti [P)-.11 F(age 10])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E/F1 11/Times-Bold@0 SF(1.)72 85
Q/F2 14/Times-Bold@0 SF(Intr)5.5 E(oduction)-.252 E F0
(Each connection be)100.8 111 Q
(gins with a question: "What is the appropriate sending rate for the)
-.165 E(current netw)100.8 124 Q(ork path?")-.11 E
(The question is not answered e)5.5 E(xplicitly)-.165 E 2.75(,b)-.715 G
(ut each TCP connection)-2.97 E
(determines the sending rate by probing the netw)100.8 137 Q
(ork path and altering the congestion)-.11 E(windo)100.8 150 Q 2.75(w\()
-.275 G(cwnd\) based on percei)-2.75 E -.165(ve)-.275 G 2.75(dc).165 G
2.75(ongestion. Each)-2.75 F(TCP connection starts with a pre-)2.75 E
(con\214gured initial congestion windo)100.8 163 Q 2.75(w\()-.275 G 2.75
(ICW\). Currently)-2.75 F 2.75(,T)-.715 G(CP allo)-2.75 E
(ws an initial windo)-.275 E 2.75(wo)-.275 G(f)-2.75 E
(between one and four MSS-sized se)100.8 176 Q
(gments \([RFC2581], [RFC3390]\).)-.165 E(The TCP)5.5 E
(connection then probes the netw)100.8 189 Q(ork for a)-.11 E -.275(va)
-.22 G(ilable bandwidth using the slo).275 E(w-start procedure)-.275 E(\
\([Jac88], [RFC2581]\), doubling cwnd during each congestion-free round\
-trip time \(R)100.8 202 Q(TT\).)-.66 E(The slo)100.8 228 Q
(w-start algorithm can be time-consuming --- especially o)-.275 E -.165
(ve)-.165 G 2.75(rn).165 G(etw)-2.75 E(orks with lar)-.11 E(ge)-.198 E
(bandwidth or long delays.)100.8 241 Q(It may tak)5.5 E 2.75(ean)-.11 G
(umber of R)-2.75 E(TTs in slo)-.66 E(w-start before the TCP)-.275 E
(connection be)100.8 254 Q(gins to fully use the a)-.165 E -.275(va)-.22
G(ilable bandwidth of the netw).275 E 2.75(ork. F)-.11 F
(or instance, it)-.165 E(tak)100.8 267 Q
(es log_2\(N\) - 2 round-trip times to b)-.11 E(uild cwnd up to N se)
-.22 E(gments, assuming an initial)-.165 E(congestion windo)100.8 280 Q
2.75(wo)-.275 G 2.75(f4s)-2.75 G -.165(eg)-2.75 G 2.75(ments. This).165
F(time in slo)2.75 E(w-start is not a problem for lar)-.275 E(ge \214le)
-.198 E(transfers, where the slo)100.8 293 Q
(w-start stage is only a fraction of the total transfer time.)-.275 E
(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G -.44(r,).165 G(in the case of mod\
erate-sized transfers the connection might carry out its entire transfe\
r in)100.8 306 Q(the slo)100.8 319 Q(w-start phase, taking man)-.275 E
2.75(yr)-.165 G(ound-trip times, where one or tw)-2.75 E 2.75(oR)-.11 G
(TTs might ha)-3.41 E -.165(ve)-.22 G(been suf)100.8 332 Q
(\214cient when using the currently a)-.275 E -.275(va)-.22 G
(ilable bandwidth along the path.).275 E 2.75(Af)100.8 358 S
(air amount of w)-2.86 E
(ork has already been done to address the issue of choosing the initial)
-.11 E(congestion windo)100.8 371 Q 2.75(wf)-.275 G(or TCP)-2.75 E 2.75
(,w)-1.221 G(ith RFC 3390 allo)-2.75 E(wing an initial windo)-.275 E
2.75(wo)-.275 G 2.75(fu)-2.75 G 2.75(pt)-2.75 G 2.75(of)-2.75 G(our)
-2.75 E(se)100.8 384 Q
(gments based on the MSS used by the connection [RFC3390].)-.165 E
(Our underlying premise)5.5 E(is that e)100.8 397 Q
(xplicit feedback from all of the routers along the path w)-.165 E
(ould be required, in the)-.11 E(current architecture, for best-ef)100.8
410 Q(fort connections to use initial windo)-.275 E
(ws signi\214cantly lar)-.275 E(ger)-.198 E(than those allo)100.8 423 Q
(wed by [RFC3390], in the absence of other information about the path.)
-.275 E(In using Quick-Start, a TCP host, say)100.8 449 Q 2.75(,h)-.715
G(ost A, w)-2.75 E(ould indicate its desired sending rate in)-.11 E(byt\
es per second, using a Quick-Start option in the IP header of a TCP pac\
k)100.8 462 Q 2.75(et. Each)-.11 F(router)2.75 E
(along the path could, in turn, either appro)100.8 475 Q .33 -.165(ve t)
-.165 H(he requested rate, reduce the requested rate, or).165 E
(indicate that the Quick-Start request is not appro)100.8 488 Q -.165
(ve)-.165 G 2.75(d. \(W).165 F 2.75(en)-.88 G
(ote that the `routers' referred to)-2.75 E(in this document also inclu\
de the IP-layer processing of the Quick-Start request at the)100.8 501 Q
(sender)100.8 514 Q 2.75(.\) In)-.605 F(appro)2.75 E
(ving a Quick-Start request, a router does not gi)-.165 E .33 -.165
(ve p)-.275 H(referential treatment to).165 E(subsequent pack)100.8 527
Q(ets from that connection;)-.11 E
(the router is only asserting that it is currently)5.5 E
(underutilized and belie)100.8 540 Q -.165(ve)-.275 G 2.75(st).165 G
(here is suf)-2.75 E(\214cient a)-.275 E -.275(va)-.22 G
(ilable bandwidth to accommodate the).275 E(sender')100.8 553 Q 2.75(sr)
-.605 G(equested rate.)-2.75 E
(The Quick-Start mechanism can determine if there are routers)5.5 E
(along the path that do not understand the Quick-Start option, or ha)
100.8 566 Q .33 -.165(ve n)-.22 H(ot agreed to the).165 E
(Quick-Start rate request.)100.8 579 Q
(TCP host B communicates the \214nal rate request to TCP host A in)5.5 E
2.75(at)100.8 592 S(ransport-le)-2.75 E -.165(ve)-.275 G 2.75(lQ).165 G
(uick-Start Response in an answering TCP pack)-2.75 E(et.)-.11 E
(If the Quick-Start request is appro)100.8 618 Q -.165(ve)-.165 G 2.75
(db).165 G 2.75(ya)-2.75 G
(ll routers along the path, then the TCP host can)-2.75 E
(send at up to the appro)100.8 631 Q -.165(ve)-.165 G 2.75(dr).165 G
(ate for a windo)-2.75 E 2.75(wo)-.275 G 2.75(fd)-2.75 G 2.75
(ata. Subsequent)-2.75 F(transmissions will be)2.75 E(go)100.8 644 Q
-.165(ve)-.165 G(rned by the def).165 E
(ault TCP congestion control mechanisms of that connection.)-.11 E
(If the)5.5 E(Quick-Start request is not appro)100.8 657 Q -.165(ve)
-.165 G(d, then the sender w).165 E(ould use the def)-.11 E
(ault congestion)-.11 E(control mechanisms.)100.8 670 Q(Quick-Start w)
100.8 696 Q(ould not be the \214rst mechanism for e)-.11 E
(xplicit communication from routers to)-.165 E
(transport protocols about sending rates.)100.8 709 Q
(Explicit Congestion Noti\214cation \(ECN\) gi)5.5 E -.165(ve)-.275 G(s)
.165 E -.165(ex)100.8 722 S(plicit congestion control feedback from rou\
ters to transport protocols, based on the).165 E(Flo)72 769 Q 212.275
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(1. [P)2.75 F(age 11])-.165
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(April 2007)2.75 E(October 2006)112.127 E
(router detecting congestion before b)100.8 85 Q(uf)-.22 E(fer o)-.275 E
-.165(ve)-.165 G(r\215o).165 E 2.75(w[)-.275 G 2.75(RFC3168]. In)-2.75 F
(contrast, routers w)2.75 E(ould)-.11 E(not use Quick-Start to gi)100.8
98 Q .33 -.165(ve c)-.275 H(ongestion information, b).165 E
(ut instead w)-.22 E(ould use Quick-Start as an)-.11 E
(optional mechanism to gi)100.8 111 Q .33 -.165(ve p)-.275 H
(ermission to transport protocols to use higher sending rates,).165 E(b\
ased on the ability of all the routers along the path to determine if t\
heir respecti)100.8 124 Q .33 -.165(ve o)-.275 H(utput).165 E
(links are signi\214cantly underutilized.)100.8 137 Q(Section 2 gi)100.8
163 Q -.165(ve)-.275 G 2.75(sa).165 G 2.75(no)-2.75 G -.165(ve)-2.915 G
(rvie).165 E 2.75(wo)-.275 G 2.75(fQ)-2.75 G 2.75(uick-Start. The)-2.75
F(formal speci\214cations for Quick-Start are)2.75 E
(contained in Sections 3, 4, 6.1.1, and 6.3.)100.8 176 Q(In particular)
5.5 E 2.75(,Q)-.44 G(uick-Start is speci\214ed for IPv4)-2.75 E
(and for IPv6 in Section 3, and is speci\214ed for TCP in Section 4.)
100.8 189 Q(Section 6 consists mostly)8.25 E(of a non-normati)100.8 202
Q .33 -.165(ve d)-.275 H
(iscussion of interactions of Quick-Start with IP tunnels and MPLS;).165
E(ho)100.8 215 Q(we)-.275 E -.165(ve)-.275 G .88 -.44(r, S).165 H
(ection 6.1.1 and 6.3 specify beha).44 E(vior for IP tunnels that are a)
-.22 E -.11(wa)-.165 G(re of Quick-).11 E(Start.)100.8 228 Q
(The rest of the document is non-normati)100.8 254 Q -.165(ve)-.275 G
2.75(,a).165 G 2.75(sf)-2.75 G(ollo)-2.75 E 2.75(ws. Section)-.275 F
2.75(5s)2.75 G(ho)-2.75 E(ws that Quick-Start is)-.275 E
(compatible with IPsec AH \(Authentication Header\).)100.8 267 Q
(Section 7 gi)5.5 E -.165(ve)-.275 G 2.75(san).165 G(on-normati)-2.75 E
.33 -.165(ve s)-.275 H(et of).165 E(guidelines for specifying Quick-Sta\
rt in other transport protocols, and Section 8 discusses)100.8 280 Q
(using Quick-Start in transport end-nodes and in routers.)100.8 293 Q
(Section 9 gi)5.5 E -.165(ve)-.275 G 2.75(sa).165 G 2.75(ne)-2.75 G
-.275(va)-3.025 G(luation of).275 E(the costs and bene\214ts of Quick-S\
tart, and Section 10 discusses implementation and)100.8 306 Q(deplo)
100.8 319 Q(yment issues.)-.11 E(The appendices discuss related w)5.5 E
(ork, Quick-Start design decisions,)-.11 E
(and possible router algorithms.)100.8 332 Q/F1 11/Times-Bold@0 SF(1.1.)
72 371 Q/F2 13/Times-Bold@0 SF(Con)5.5 E -.13(ve)-.52 G(ntions and T).13
E(erminology)-1.196 E F0(The k)100.8 397 Q .33 -.165(ey w)-.11 H
(ords "MUST", "MUST NO).055 E(T", "REQ)-.44 E
(UIRED", "SHALL", "SHALL NO)-.11 E(T",)-.44 E("SHOULD", "SHOULD NO)100.8
410 Q(T", "RECOMMENDED", "MA)-.44 E(Y", and "OPTION)-1.155 E
(AL" in this)-.385 E
(document are to be interpreted as described in [RFC2119].)100.8 423 Q
F1(2.)72 462 Q/F3 14/Times-Bold@0 SF(Assumptions and General Principles)
5.5 E F0(This section describes the assumptions and general principles \
behind the design of the)100.8 488 Q(Quick-Start mechanism.)100.8 501 Q
(Assumptions:)100.8 527 Q 2.75(*T)100.8 553 S
(he data transfer in the tw)-2.75 E 2.75(od)-.11 G
(irections of a connection tra)-2.75 E -.165(ve)-.22 G(rses dif).165 E
(ferent queues, and)-.275 E(possibly e)100.8 566 Q -.165(ve)-.275 G 2.75
(nd).165 G(if)-2.75 E(ferent routers.)-.275 E(Thus, an)5.5 E 2.75(ym)
-.165 G(echanism for determining the allo)-2.75 E(wed sending)-.275 E
(rate w)100.8 579 Q(ould ha)-.11 E .33 -.165(ve t)-.22 H 2.75(ob).165 G
2.75(eu)-2.75 G(sed independently for each direction.)-2.75 E 2.75(*T)
100.8 605 S(he path between the tw)-2.75 E 2.75(oe)-.11 G
(ndpoints is relati)-2.75 E -.165(ve)-.275 G
(ly stable, such that the path used by the).165 E(Quick-Start request i\
s generally the same path used by the Quick-Start pack)100.8 618 Q
(ets one round-)-.11 E(trip time later)100.8 631 Q 5.5(.[)-.605 G
(ZDPS01] sho)-5.5 E(ws this assumption should be generally v)-.275 E
2.75(alid. Ho)-.275 F(we)-.275 E -.165(ve)-.275 G -.44(r,).165 G([RFC38\
19] discusses a range of Bandwidth on Demand subnets that could cause t\
he)100.8 644 Q(characteristics of the path to change o)100.8 657 Q -.165
(ve)-.165 G 2.75(rt).165 G(ime.)-2.75 E 2.75(*A)100.8 683 S .33 -.165
(ny n)-2.75 H .55 -.275(ew m).165 H
(echanism must be incrementally deplo).275 E
(yable, and might not be supported by)-.11 E
(all of the routers and/or end-hosts.)100.8 696 Q(Thus, an)5.5 E 2.75
(yn)-.165 G .55 -.275(ew m)-2.75 H(echanism must be able to).275 E(acco\
mmodate non-supporting routers or end-hosts without disturbing the curr\
ent Internet)100.8 709 Q 2.75(semantics. W)100.8 722 R 2.75(en)-.88 G
(ote that while Quick-Start is incrementally deplo)-2.75 E
(yable in this sense, a)-.11 E(Flo)72 769 Q 212.275
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(2. [P)2.75 F(age 12])-.165
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(April 2007)2.75 E(October 2006)112.127 E
(Quick-Start request cannot be appro)100.8 85 Q -.165(ve)-.165 G 2.75
(df).165 G(or a particular connection unless both end-nodes)-2.75 E
(and all of the routers along the path ha)100.8 98 Q .33 -.165(ve b)-.22
H(een con\214gured to support Quick-Start.).165 E(General Principles:)
100.8 124 Q 2.75(*O)100.8 150 S(ur underlying premise is that e)-2.75 E
(xplicit feedback from all of the routers along the path)-.165 E -.11
(wo)100.8 163 S
(uld be required, in the current architecture, for best-ef).11 E
(fort connections to use initial)-.275 E(windo)100.8 176 Q
(ws signi\214cantly lar)-.275 E(ger than those allo)-.198 E
(wed by [RFC3390], in the absence of other)-.275 E
(information about the path.)100.8 189 Q 2.75(*Ar)100.8 215 S
(outer should only appro)-2.75 E .33 -.165(ve a Q)-.165 H
(uick-Start request if the output link is underutilized.).165 E(An)100.8
228 Q 2.75(yo)-.165 G(ther approach will result in either per)-2.75 E
(-\215o)-.22 E 2.75(ws)-.275 G(tate at the router)-2.75 E 2.75(,o)-.44 G
2.75(rt)-2.75 G(he possibility of a)-2.75 E
(\(possibly transient\) queue at the router)100.8 241 Q(.)-.605 E 2.75
(*N)100.8 267 S 2.75(op)-2.75 G(er)-2.75 E(-\215o)-.22 E 2.75(ws)-.275 G
(tate should be required at the router)-2.75 E 5.5(.N)-.605 G
(ote that while per)-5.5 E(-\215o)-.22 E 2.75(ws)-.275 G(tate is not)
-2.75 E(required, we also do not preclude a router from storing per)
100.8 280 Q(-\215o)-.22 E 2.75(ws)-.275 G(tate for making Quick-)-2.75 E
(Start decisions or for checking for misbeha)100.8 293 Q(ving nodes.)
-.22 E/F1 11/Times-Bold@0 SF(2.1.)72 332 Q/F2 13/Times-Bold@0 SF(Ov)5.5
E(er)-.13 E(view of Quick-Start)-.13 E F0(In this section we gi)100.8
358 Q .33 -.165(ve a)-.275 H 2.75(no).165 G -.165(ve)-2.915 G(rvie).165
E 2.75(wo)-.275 G 2.75(ft)-2.75 G
(he use of Quick-Start with TCP to request a higher)-2.75 E
(congestion windo)100.8 371 Q 4.18 -.715(w. T)-.275 H
(he description in this section is non-normati).715 E -.165(ve)-.275 G
2.75(;t).165 G(he normati)-2.75 E -.165(ve)-.275 G
(description of Quick-Start with IP and TCP follo)100.8 384 Q
(ws in Sections 3 and 4.)-.275 E(Quick-Start could)5.5 E(be used in the\
 middle of a connection, e.g., after an idle or underutilized period, a\
s well as)100.8 397 Q(for the initial sending rate; these uses of Quick\
-Start are discussed later in the document.)100.8 410 Q
(Quick-Start requires end-points and routers to w)100.8 436 Q
(ork together)-.11 E 2.75(,w)-.44 G(ith end-points requesting a)-2.75 E
(higher sending rate in the Quick-Start \(QS\) option in IP)100.8 449 Q
2.75(,a)-1.221 G(nd routers along the path)-2.75 E(appro)100.8 462 Q
(ving, modifying, discarding or ignoring \(and therefore disallo)-.165 E
(wing\) the Quick-Start)-.275 E 2.75(Request. The)100.8 475 R(recei)2.75
E -.165(ve)-.275 G 2.75(ru).165 G(ses reliable, transport-le)-2.75 E
-.165(ve)-.275 G 2.75(lm).165 G(echanisms to inform the sender of the)
-2.75 E(status of the Quick-Start Request.)100.8 488 Q -.165(Fo)5.5 G
2.75(re).165 G(xample, when TCP is used, the TCP recei)-2.915 E -.165
(ve)-.275 G 2.75(rs).165 G(ends)-2.75 E(feedback to the sender using a \
Quick-Start Response option in the TCP header)100.8 501 Q 5.5(.I)-.605 G
(n)-5.5 E(addition, Quick-Start assumes a unicast, congestion-controlle\
d transport protocol; we do)100.8 514 Q
(not consider the use of Quick-Start for multicast traf)100.8 527 Q
(\214c.)-.275 E(When sent as a request, the Quick-Start Option includes\
 a request for a sending rate in bits)100.8 553 Q
(per second, and a Quick-Start TTL \(QS TTL\) to be decremented by e)
100.8 566 Q -.165(ve)-.275 G(ry router along the).165 E
(path that understands the option and appro)100.8 579 Q -.165(ve)-.165 G
2.75(st).165 G(he request.)-2.75 E(The Quick-Start TTL is)5.5 E
(initialized by the sender to a random v)100.8 592 Q 2.75(alue. The)
-.275 F(transport recei)2.75 E -.165(ve)-.275 G 2.75(rr).165 G
(eturns the rate,)-2.75 E(information about the TTL and the Quick-Start\
 Nonce to the sender using transport-le)100.8 605 Q -.165(ve)-.275 G(l)
.165 E(mechanisms; for TCP)100.8 618 Q 2.75(,t)-1.221 G(he recei)-2.75 E
-.165(ve)-.275 G 2.75(rs).165 G
(ends this information in the Quick-Start Response in)-2.75 E
(the TCP header)100.8 631 Q 5.5(.I)-.605 G 2.75(np)-5.5 G(articular)
-2.75 E 2.75(,t)-.44 G(he recei)-2.75 E -.165(ve)-.275 G 2.75(rc).165 G
(omputes the dif)-2.75 E(ference between the Quick-)-.275 E(Start TTL a\
nd the IP TTL \(the TTL in the IP header\) of the Quick-Start request p\
ack)100.8 644 Q(et, and)-.11 E
(returns this in the Quick-Start response.)100.8 657 Q
(The sender uses the TTL dif)5.5 E(ference to determine)-.275 E(if all \
of the routers along the path decremented the Quick-Start TTL, appro)
100.8 670 Q(ving the Quick-)-.165 E(Start Request.)100.8 683 Q
(If the request is appro)100.8 709 Q -.165(ve)-.165 G 2.75(db).165 G
2.75(ya)-2.75 G(ll of the routers along the path, then the TCP sender)
-2.75 E(combines this allo)100.8 722 Q
(wed rate with the measurement of the round-trip time, and ends up with)
-.275 E(Flo)72 769 Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F
2.75(2.1. [P)2.75 F(age 13])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(an allo)100.8 85 Q
(wed TCP congestion windo)-.275 E 4.18 -.715(w. T)-.275 H(his windo).715
E 2.75(wi)-.275 G 2.75(ss)-2.75 G(ent rate-paced o)-2.75 E -.165(ve)
-.165 G 2.75(rt).165 G(he ne)-2.75 E(xt round-)-.165 E
(trip time, or until an A)100.8 98 Q(CK pack)-.44 E(et is recei)-.11 E
-.165(ve)-.275 G(d.).165 E(Figure 1 sho)100.8 124 Q
(ws a successful use of Quick-Start, with the sender')-.275 E 2.75(sI)
-.605 G 2.75(Pl)-2.75 G(ayer and both routers)-2.75 E
(along the path appro)100.8 137 Q
(ving the Quick-Start Request, and the TCP recei)-.165 E -.165(ve)-.275
G 2.75(ru).165 G(sing the Quick-)-2.75 E
(Start Response to return information to the TCP sender)100.8 150 Q 5.5
(.I)-.605 G 2.75(nt)-5.5 G(his e)-2.75 E(xample, Quick-Start is)-.165 E
(used by TCP to establish the initial congestion windo)100.8 163 Q -.715
(w.)-.275 G/F1 11/Courier@0 SF 46.2(Sender Router)120.6 195 R 46.2(1R)
6.6 G(outer 2)-46.2 E(Receiver)66 E 46.2(------ --------)120.6 208 R
59.4(-------- --------)46.2 F 6.6(|<)107.4 221 S(IP TTL: 63>)-6.6 E 6.6
(|<)107.4 234 S(QS TTL: 91>)-6.6 E 6.6(|<)107.4 247 S(TTL Diff: 28>)-6.6
E 6.6(|Q)107.4 260 S(uick-Start Request)-6.6 E 6.6(|i)107.4 273 S 6.6
(nS)-6.6 G(YN or SYN/ACK.)-6.6 E 6.6(|I)107.4 286 S(P: Decrement QS TTL)
-6.6 E 6.6(|t)107.4 299 S 6.6(oa)-6.6 G(pprove request -->)-6.6 E(|)
107.4 312 Q 99(|D)107.4 325 S(ecrement)-99 E 99(|Q)107.4 338 S 6.6(ST)
-99 G(TL)-6.6 E 99(|t)107.4 351 S 6.6(oa)-99 G(pprove)-6.6 E 99(|r)107.4
364 S(equest -->)-99 E(|)107.4 377 Q 198(|D)107.4 390 S(ecrement)-198 E
198(|Q)107.4 403 S 6.6(ST)-198 G(TL)-6.6 E 198(|t)107.4 416 S 6.6(oa)
-198 G(pprove)-6.6 E 198(|r)107.4 429 S(equest -->)-198 E(|)107.4 442 Q
283.8(|<)107.4 455 S(IP TTL: 60>)-283.8 E 283.8(|<)107.4 468 S
(QS TTL: 88>)-283.8 E 283.8(|<)107.4 481 S(TTL Diff: 28>)-283.8 E 283.8
(|R)107.4 494 S(eturn Quick-Start)-283.8 E 290.4(|i)107.4 507 S
(nfo to sender in)-290.4 E 283.8(|Q)107.4 520 S(uick-Start Response)
-283.8 E 277.2(|<)107.4 533 S(-- in TCP ACK packet.)-277.2 E(|)107.4 546
Q 6.6(|<)107.4 559 S(TTL Diff: 28>)-6.6 E 6.6(|Q)107.4 572 S
(uick-Start approved,)-6.6 E 6.6(|t)107.4 585 S(ranslate to cwnd.)-6.6 E
6.6(|R)107.4 598 S(eport Approved Rate.)-6.6 E 6.6(VS)107.4 611 S
(end cwnd paced over one RTT. -->)-6.6 E
(Figure 1: A successful Quick-Start Request.)173.4 637 Q F0
(Figure 2 sho)100.8 669 Q(ws an unsuccessful use of Quick-Start, with o\
ne of the routers along the path)-.275 E(not appro)100.8 682 Q
(ving the Quick-Start Request.)-.165 E
(If the Quick-Start Request is not appro)5.5 E -.165(ve)-.165 G(d, then)
.165 E(the sender uses the def)100.8 695 Q
(ault congestion control mechanisms for that transport protocol,)-.11 E
(including the def)100.8 708 Q(ault initial congestion windo)-.11 E 1.43
-.715(w, r)-.275 H(esponse to idle periods, etc.).715 E(Flo)72 769 Q
204.025(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(2.1. [P)2.75 F
(age 14])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E/F1 11/Courier@0 SF 46.2
(Sender Router)120.6 85 R 46.2(1R)6.6 G(outer 2)-46.2 E(Receiver)66 E
46.2(------ --------)120.6 98 R 59.4(-------- --------)46.2 F 6.6(|<)
107.4 111 S(IP TTL: 63>)-6.6 E 6.6(|<)107.4 124 S(QS TTL: 91>)-6.6 E 6.6
(|<)107.4 137 S(TTL Diff: 28>)-6.6 E 6.6(|Q)107.4 150 S
(uick-Start Request)-6.6 E 6.6(|i)107.4 163 S 6.6(nS)-6.6 G
(YN or SYN/ACK.)-6.6 E 6.6(|I)107.4 176 S(P: Decrement QS TTL)-6.6 E 6.6
(|t)107.4 189 S 6.6(oa)-6.6 G(pprove request -->)-6.6 E(|)107.4 202 Q 99
(|D)107.4 215 S(ecrement)-99 E 99(|Q)107.4 228 S 6.6(ST)-99 G(TL)-6.6 E
99(|t)107.4 241 S 6.6(oa)-99 G(pprove)-6.6 E 99(|r)107.4 254 S
(equest -->)-99 E(|)107.4 267 Q 198(|F)107.4 280 S(orward packet)-198 E
198(|w)107.4 293 S(ithout modifying)-198 E 198(|Q)107.4 306 S
(uick-Start Option. -->)-198 E(|)107.4 319 Q 283.8(|<)107.4 332 S
(IP TTL: 60>)-283.8 E 283.8(|<)107.4 345 S(QS TTL: 89>)-283.8 E 283.8
(|<)107.4 358 S(TTL Diff: 29>)-283.8 E 283.8(|R)107.4 371 S
(eturn Quick-Start)-283.8 E 290.4(|i)107.4 384 S(nfo to sender in)-290.4
E 283.8(|Q)107.4 397 S(uick-Start Response)-283.8 E 277.2(|<)107.4 410 S
(-- in TCP ACK packet.)-277.2 E(|)107.4 423 Q 6.6(|<)107.4 436 S
(TTL Diff: 29>)-6.6 E 6.6(|Q)107.4 449 S(uick-Start not approved.)-6.6 E
6.6(|R)107.4 462 S(eport Approved Rate.)-6.6 E 6.6(VU)107.4 475 S
(se default initial cwnd. -->)-6.6 E
(Figure 2: An unsuccessful Quick-Start Request.)173.4 501 Q/F2 11
/Times-Bold@0 SF(3.)72 546 Q/F3 14/Times-Bold@0 SF
(The Quick-Start Option in IP)5.5 E F2(3.1.)72 585 Q/F4 13/Times-Bold@0
SF(The Quick-Start Option f)5.5 E(or IPv4)-.325 E F0
(The Quick-Start Request for IPv4 is de\214ned as follo)100.8 611 Q(ws:)
-.275 E(Flo)72 769 Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F
2.75(3.1. [P)2.75 F(age 15])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E/F1 11/Courier@0 SF 125.4(0123)
107.4 85 S 6.6(01234567890123456789012345678901)107.4 98 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
111 Q 19.8(|O)100.8 124 S 33(ption |)-19.8 F 26.4(Length=8 |)13.2 F
(Func. | Rate)6.6 E 19.8(|Q)13.2 G 6.6(ST)-19.8 G 33(TL |)-6.6 F 99(|||)
100.8 137 S 6.6(0000 |Request|)-92.4 F(|)99 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
150 Q 158.4(|Q)100.8 163 S 6.6(SN)-158.4 G 171.6(once |)-6.6 F 6.6(R|)
6.6 G(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
100.8 176 Q(Figure 3.)120.6 202 Q(The Quick-Start Option for IPv4.)13.2
E 6.6(AQ)219.6 215 S(uick-Start Request.)-6.6 E F0(The \214rst byte con\
tains the option \214eld, which includes the one-bit cop)100.8 247 Q
2.75<798d>-.11 G(ag, the 2-bit class)-2.75 E
(\214eld, and the 5-bit option number \(to be assigned by IAN)100.8 260
Q(A\).)-.385 E(The second byte contains the length \214eld, indicating \
an option length of eight bytes.)100.8 286 Q
(The third byte includes a four)100.8 312 Q(-bit Function \214eld.)-.22
E(If the Function \214eld is set to "0000", then)5.5 E
(the Quick-Start Option is a Rate Request.)100.8 325 Q
(In this case, the second half of the third byte is a)5.5 E(four)100.8
338 Q(-bit Rate Request \214eld.)-.22 E -.165(Fo)100.8 364 S 2.75(raR)
.165 G(ate Request, the fourth byte contains the Quick-Start TTL \(QS T\
TL\) \214eld.)-2.75 E(The)5.5 E
(sender MUST set the QS TTL \214eld to a random v)100.8 377 Q 2.75
(alue. Routers)-.275 F(that appro)2.75 E .33 -.165(ve t)-.165 H
(he Quick-).165 E(Start Request decrement the QS TTL \(mod 256\) by the\
 same amount that the)100.8 390 Q 2.75(yd)-.165 G(ecrement)-2.75 E
(the IP TTL.)100.8 403 Q(\(As else)5.5 E
(where in this document, we use the term `router' imprecisely to also)
-.275 E
(include the Quick-Start functionality at the IP layer at the sender)
100.8 416 Q 2.75(.\) The)-.605 F(QS TTL is used by)2.75 E(the sender to\
 detect if all of the routers along the path understood and appro)100.8
429 Q -.165(ve)-.165 G 2.75(dt).165 G(he Quick-)-2.75 E(Start option.)
100.8 442 Q -.165(Fo)100.8 468 S 2.75(raR).165 G
(ate Request, the transport sender MUST calculate and store the TTL Dif)
-2.75 E(f, the)-.275 E(dif)100.8 481 Q(ference between the IP TTL v)
-.275 E(alue and the QS TTL v)-.275 E(alue in the Quick-Start request)
-.275 E(pack)100.8 494 Q(et, as follo)-.11 E(ws:)-.275 E(TTL Dif)100.8
520 Q 2.75(f=\(I)-.275 G 2.75(PT)-2.75 G(TL - QS TTL \) mod 256)-2.75 E
(\(1\))68.75 E -.165(Fo)100.8 546 S 2.75(raR).165 G(ate Request, bytes \
5-8 contain a 30-bit QS Nonce, discussed in Section 3.4, and a)-2.75 E
(tw)100.8 559 Q(o-bit Reserv)-.11 E(ed \214eld.)-.165 E
(The sender SHOULD set the reserv)5.5 E
(ed \214eld to zero, and routers and)-.165 E(recei)100.8 572 Q -.165(ve)
-.275 G(rs SHOULD ignore the reserv).165 E(ed \214eld.)-.165 E
(The sender SHOULD set the 30-bit QS)5.5 E(Nonce to a random v)100.8 585
Q(alue.)-.275 E(The sender initializes the Rate Request to the desired \
sending rate, including an estimate of)100.8 611 Q
(the transport and IP header o)100.8 624 Q -.165(ve)-.165 G 2.75
(rhead. The).165 F(encoding function for the Rate Request sets the)2.75
E(request rate to K*2^N bps \(bits per second\), for N the v)100.8 637 Q
(alue in the Rate Request \214eld, and)-.275 E(for K set to 40,000.)
100.8 650 Q -.165(Fo)5.5 G 2.75(rN).165 G(=0, the rate request w)-2.75 E
(ould be set to zero, re)-.11 E -.055(ga)-.165 G(rdless of the).055 E
(encoding function.)100.8 663 Q(This is illustrated in T)5.5 E
(able 1 belo)-.88 E 4.18 -.715(w. F)-.275 H(or the four).55 E
(-bit Rate Request \214eld,)-.22 E
(the request range is from 80 Kbps to 1.3 Gbps.)100.8 676 Q
(Alternate encodings that were considered)5.5 E
(for the Rate Request are gi)100.8 689 Q -.165(ve)-.275 G 2.75(ni).165 G
2.75(nA)-2.75 G(ppendix B.2.)-2.75 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.1. [P)2.75 F(age 16])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E/F1 11/Courier@0 SF 33(NR)107.4
85 S(ate Request \(in Kbps\))-33 E 19.8(--- -------------------)100.8 98
R 79.2(00)107.4 111 S 72.6(18)107.4 124 S(0)-72.6 E 66(21)107.4 137 S
(60)-66 E 66(33)107.4 150 S(20)-66 E 66(46)107.4 163 S(40)-66 E 52.8(51)
107.4 176 S(,280)-52.8 E 52.8(62)107.4 189 S(,560)-52.8 E 52.8(75)107.4
202 S(,120)-52.8 E 46.2(81)107.4 215 S(0,240)-46.2 E 46.2(92)107.4 228 S
(0,480)-46.2 E 39.6(10 40,960)100.8 241 R 39.6(11 81,920)100.8 254 R 33
(12 163,840)100.8 267 R 33(13 327,680)100.8 280 R 33(14 655,360)100.8
293 R 19.8(15 1,310,720)100.8 306 R
(Table 1: Mapping from Rate Request field to rate request in Kbps.)100.8
332 Q F0(Routers can appro)100.8 364 Q .33 -.165(ve t)-.165 H
(he Quick-Start Request for a lo).165 E(wer rate by decreasing the Rate)
-.275 E(Request in the Quick-Start Request.)100.8 377 Q
(Section 4.2 discusses the Quick-Start Response from)5.5 E
(the TCP recei)100.8 390 Q -.165(ve)-.275 G 2.75(rt).165 G 2.75(ot)-2.75
G(he TCP sender)-2.75 E 2.75(,a)-.44 G
(nd Section 4.4 discusses the TCP sender')-2.75 E(s)-.605 E
(mechanism for determining if a Quick-Start Request has been appro)100.8
403 Q -.165(ve)-.165 G(d.).165 E F1 125.4(0123)107.4 435 S 6.6
(01234567890123456789012345678901)107.4 448 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
461 Q 19.8(|O)100.8 474 S 33(ption |)-19.8 F 26.4(Length=8 |)13.2 F
(Func. | Rate)6.6 E 19.8(|N)13.2 G(ot Used)-19.8 E(|)26.4 E 99(|||)100.8
487 S 6.6(1000 |)-92.4 F 92.4(Report| |)6.6 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
500 Q 158.4(|Q)100.8 513 S 6.6(SN)-158.4 G 171.6(once |)-6.6 F 6.6(R|)
6.6 G(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
100.8 526 Q(Figure 4.)120.6 552 Q(The Quick-Start Option for IPv4.)13.2
E(Report of Approved Rate.)219.6 565 Q F0(If the Function \214eld in th\
e third byte of the Quick-Start Option is set to "1000", then the)100.8
597 Q(Quick-Start Option is a Report of Appro)100.8 610 Q -.165(ve)-.165
G 2.75(dR).165 G 2.75(ate. In)-2.75 F
(this case the second four bits in the)2.75 E
(third byte are the Rate Report \214eld, formatted e)100.8 623 Q
(xactly as in the Rate Request \214eld in a Rate)-.165 E 2.75
(Request. F)100.8 636 R(or a Report of Appro)-.165 E -.165(ve)-.165 G
2.75(dR).165 G(ate, the fourth byte of the Quick-Start Option are not)
-2.75 E 2.75(used. Bytes)100.8 649 R
(5-8 contain a 30-bit QS Nonce and a tw)2.75 E(o- bit Reserv)-.11 E
(ed \214eld.)-.165 E(After an appro)100.8 675 Q -.165(ve)-.165 G 2.75
(dR).165 G(ate Request, the sender MUST report the Appro)-2.75 E -.165
(ve)-.165 G 2.75(dR).165 G(ate, using a)-2.75 E
(Quick-Start Option con\214gured as a Report of Appro)100.8 688 Q -.165
(ve)-.165 G 2.75(dR).165 G(ate with the Rate Report \214eld set)-2.75 E
(to the appro)100.8 701 Q -.165(ve)-.165 G 2.75(dr).165 G
(ate, and the QS Nonce set to the QS Nonce sent in the Quick-Start)-2.75
E 2.75(Request. The)100.8 714 R(pack)2.75 E
(et containing the Report of Appro)-.11 E -.165(ve)-.165 G 2.75(dR).165
G(ate MUST be either a control)-2.75 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.1. [P)2.75 F(age 17])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E(pack)100.8 85 Q
(et sent before the \214rst Quick-Start data pack)-.11 E
(et, or a Quick-Start Option in the \214rst data)-.11 E(pack)100.8 98 Q
(et itself.)-.11 E(The Report of Appro)5.5 E -.165(ve)-.165 G 2.75(dR)
.165 G(ate does not ha)-2.75 E .33 -.165(ve t)-.22 H 2.75(ob).165 G 2.75
(es)-2.75 G(ent reliably; for e)-2.75 E(xample,)-.165 E(if the appro)
100.8 111 Q -.165(ve)-.165 G 2.75(dr).165 G
(ate is reported in a separate control pack)-2.75 E
(et, the sender does not necessarily)-.11 E(kno)100.8 124 Q 2.75(wi)
-.275 G 2.75(ft)-2.75 G(he control pack)-2.75 E
(et has been dropped in the netw)-.11 E 2.75(ork. If)-.11 F(the pack)
2.75 E(et contained the)-.11 E(Quick-Start Request is ackno)100.8 137 Q
(wledged, b)-.275 E(ut the ackno)-.22 E(wledgement pack)-.275 E
(et does not contain a)-.11 E(Quick-Start Response, then the sender MUS\
T assume that the Quick-Start Request w)100.8 150 Q(as)-.11 E
(denied, and set a Report of Appro)100.8 163 Q -.165(ve)-.165 G 2.75(dR)
.165 G(ate with a rate of zero.)-2.75 E(Routers may choose to)5.5 E
(ignore the Report of Appro)100.8 176 Q -.165(ve)-.165 G 2.75(dR).165 G
(ate, or to use the Report of Appro)-2.75 E -.165(ve)-.165 G 2.75(dR)
.165 G(ate b)-2.75 E(ut ignore the)-.22 E(QS Nonce.)100.8 189 Q
(Alternately)5.5 E 2.75(,s)-.715 G
(ome routers that use the Report of Appro)-2.75 E -.165(ve)-.165 G 2.75
(dR).165 G(ate may choose to)-2.75 E(match the QS Nonce, mask)100.8 202
Q(ed by the appro)-.11 E -.165(ve)-.165 G 2.75(dr).165 G
(ate, with the QS Nonce seen in the original)-2.75 E(request.)100.8 215
Q(If the Rate Request is denied, the sender MUST send a Report of Appro)
100.8 241 Q -.165(ve)-.165 G 2.75(dR).165 G(ate with the)-2.75 E
(Rate Report \214eld set to zero.)100.8 254 Q 1.76 -.88(We n)100.8 280 T
(ote that unlik).88 E 2.75(eaQ)-.11 G(uick-Start Request sent at the be)
-2.75 E(ginning of a connection, when a)-.165 E(Quick-Start Request is \
sent in the middle of a connection, the connection could already)100.8
293 Q(ha)100.8 306 Q .33 -.165(ve a)-.22 H 2.75(ne).165 G
(stablished congestion windo)-2.75 E 2.75(wo)-.275 G 2.75(rs)-2.75 G
(ending rate.)-2.75 E(The Rate Request is the requested)5.5 E(total rat\
e for the connection, including the current rate of the connection; the\
 Rate Request)100.8 319 Q
(is *not* a request for an additional sending rate o)100.8 332 Q -.165
(ve)-.165 G 2.75(ra).165 G(nd abo)-2.75 E .33 -.165(ve t)-.165 H
(he current sending rate.).165 E(If)5.5 E
(the Rate Request is denied, or lo)100.8 345 Q(wered to a v)-.275 E
(alue belo)-.275 E 2.75(wt)-.275 G(he connection')-2.75 E 2.75(sc)-.605
G(urrent sending)-2.75 E
(rate, then the sender ignores the request, and re)100.8 358 Q -.165(ve)
-.275 G(rts to the def).165 E(ault congestion control)-.11 E
(mechanisms of the transport protocol.)100.8 371 Q(The use of the Quick\
-Start Option does not require the additional use of the Router Alert)
100.8 397 Q(Option [RFC2113].)100.8 410 Q 1.76 -.88(We n)100.8 436 T(ot\
e that in IPv4, a change in IP options at routers requires recalculatin\
g the IP header).88 E(checksum.)100.8 449 Q/F1 11/Times-Bold@0 SF(3.2.)
72 488 Q/F2 13/Times-Bold@0 SF(The Quick-Start Option f)5.5 E(or IPv6)
-.325 E F0
(The Quick-Start Option for IPv6 is placed in the Hop-by-Hop Options e)
100.8 514 Q(xtension header)-.165 E(that is processed at e)100.8 527 Q
-.165(ve)-.275 G(ry netw).165 E
(ork node along the communication path [RFC2460]. The)-.11 E
(option format follo)100.8 540 Q
(wing the generic Hop-by-Hop Options header is identical to the IPv4)
-.275 E(format, with the e)100.8 553 Q
(xception that the Length \214eld should e)-.165 E
(xclude the common type and)-.165 E(length \214elds in the option forma\
t and be set to 6 bytes instead of 8 bytes.)100.8 566 Q -.165(Fo)100.8
592 S 2.75(raQ).165 G(uick-Start Request, the transport recei)-2.75 E
-.165(ve)-.275 G 2.75(rc).165 G(ompares the Quick-Start TTL with the)
-2.75 E(IPv6 Hop Limit \214eld to calculate the TTL Dif)100.8 605 Q 2.75
(f. \(The)-.275 F(Hop Limit in IPv6 is the equi)2.75 E -.275(va)-.275 G
(lent).275 E(of the TTL in IPv4.\))100.8 618 Q(That is, TTL Dif)5.5 E
2.75(fM)-.275 G(UST be calculated and stored as follo)-2.75 E(ws:)-.275
E(TTL Dif)100.8 644 Q 2.75(f=\(I)-.275 G
(Pv6 Hop Limit - QS TTL \) mod 256)-2.75 E(\(2\))49.5 E(Unlik)100.8 670
Q 2.75(eI)-.11 G(Pv4, modifying or deleting the Quick-Start IPv6 Option\
 does not require checksum)-2.75 E
(re-calculation, because the IPv6 header does not ha)100.8 683 Q .33
-.165(ve a c)-.22 H(hecksum \214eld, and modifying the).165 E
(Quick-Start Request in the IPv6 Hop-by-Hop options header does not af)
100.8 696 Q(fect the IPv6)-.275 E(pseudo-header checksum used in upper)
100.8 709 Q(-layer checksum calculations.)-.22 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.2. [P)2.75 F(age 18])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E
(Appendix A of RFC 2460 requires that all pack)100.8 85 Q
(ets with the same \215o)-.11 E 2.75(wl)-.275 G(abel must be)-2.75 E
(originated with the same hop-by-hop header contents, which w)100.8 98 Q
(ould be incompatible with)-.11 E(Quick-Start. Ho)100.8 111 Q(we)-.275 E
-.165(ve)-.275 G .88 -.44(r, a l).165 H(ater IPv6 \215o).44 E 2.75(wl)
-.275 G(abel speci\214cation [RFC3697] updates the use of)-2.75 E<8d6f>
100.8 124 Q 2.75(wl)-.275 G(abels in IPv6 and remo)-2.75 E -.165(ve)
-.165 G 2.75(st).165 G
(his restriction. Therefore Quick-Start is compatible with)-2.75 E
(the current IPv6 speci\214cations.)100.8 137 Q/F1 11/Times-Bold@0 SF
(3.3.)72 189 Q/F2 13/Times-Bold@0 SF(Pr)5.5 E
(ocessing the Quick-Start Request at Routers)-.234 E F0(The Quick-Start\
 Request does not report the current sending rate of the connection sen\
ding)100.8 215 Q(the request; in the def)100.8 228 Q(ault case of a rou\
ter \(or IP layer implementation at an end-node\) that)-.11 E
(does not maintain per)100.8 241 Q(-\215o)-.22 E 2.75(ws)-.275 G
(tate, a router mak)-2.75 E(es the conserv)-.11 E(ati)-.275 E .33 -.165
(ve a)-.275 H(ssumption that the \215o).165 E(w')-.275 E(s)-.605 E
(current sending rate is zero.)100.8 254 Q
(Each participating router can either terminate or appro)5.5 E .33 -.165
(ve t)-.165 H(he).165 E(Quick-Start Request.)100.8 267 Q 2.75(Ar)5.5 G
(outer MUST only appro)-2.75 E .33 -.165(ve a Q)-.165 H
(uick-Start request if the output link).165 E(is underutilized, and if \
the router judges that the output link will continue to be)100.8 280 Q
(underutilized if this and earlier appro)100.8 293 Q -.165(ve)-.165 G
2.75(dr).165 G(equests are used by the senders.)-2.75 E(Otherwise, the)
5.5 E(router reduces or terminates the Quick-Start Request.)100.8 306 Q
(While the paragraph abo)100.8 332 Q .33 -.165(ve d)-.165 H
(e\214nes the *semantics* of appro).165 E
(ving a Quick-Start request, this)-.165 E(document does not specify the\
 speci\214c algorithms to be used by routers in processing)100.8 345 Q
(Quick-Start Requests or Reports.)100.8 358 Q
(This is similar to RFC 3168, which speci\214cs the)5.5 E
(semantics of the ECN codepoints in the IP header)100.8 371 Q 2.75(,b)
-.44 G(ut does not specify speci\214c algorithms)-2.97 E
(for routers to use in deciding when to drop or mark pack)100.8 384 Q
(ets before b)-.11 E(uf)-.22 E(fer o)-.275 E -.165(ve)-.165 G(r\215o)
.165 E -.715(w.)-.275 G 2.75(Ar)100.8 410 S(outer that wishes to termin\
ate the Quick-Start Request SHOULD either delete the)-2.75 E(Quick-Star\
t Request from the IP header or zero the QS TTL, QS Nonce, and Rate Req\
uest)100.8 423 Q 2.75(\214elds. Deleting)100.8 436 R
(the Quick-Start Request sa)2.75 E -.165(ve)-.22 G 2.75(sr).165 G
(esources because do)-2.75 E(wnstream routers will)-.275 E(ha)100.8 449
Q .33 -.165(ve n)-.22 H 2.75(oo).165 G(ption to process, b)-2.75 E
(ut zeroing the Rate Request \214eld may be more ef)-.22 E
(\214cient for)-.275 E(routers to implement.)100.8 462 Q
(As suggested in [B05], future additions to Quick-Start could de\214ne)
5.5 E(error codes for routers to insert into the QS Nonce \214eld to re\
port back to the sender the)100.8 475 Q
(reason that the Quick-Start request w)100.8 488 Q
(as denied, e.g., that the router is den)-.11 E(ying all Quick-)-.165 E
(Start requests at this time, or that this router as a matter of polic)
100.8 501 Q 2.75(yd)-.165 G(oes not grant Quick-)-2.75 E
(Start requests.)100.8 514 Q 2.75(Ar)5.5 G(outer that doesn')-2.75 E
2.75(tu)-.198 G(nderstand the Quick-Start option will simply forw)-2.75
E(ard)-.11 E(the pack)100.8 527 Q
(et with the Quick-Start Request unchanged \(ensuring that the TTL Dif)
-.11 E 2.75(fw)-.275 G(ill not)-2.75 E
(match and Quick-Start will not be used\).)100.8 540 Q
(If the participating router has decided to appro)100.8 566 Q .33 -.165
(ve t)-.165 H(he Quick-Start Request, it does the).165 E(follo)100.8 579
Q(wing:)-.275 E 2.75(*T)100.8 605 S(he router MUST decrement the QS TTL\
 by the amount the IP TTL is decremented)-2.75 E(\(usually one\).)100.8
618 Q 2.75(*I)100.8 644 S 2.75(ft)-2.75 G
(he router is only willing to appro)-2.75 E .33 -.165(ve a R)-.165 H
(ate Request less than that in the Quick-Start).165 E
(Request, then the router replaces the Rate Request with a smaller v)
100.8 657 Q 2.75(alue. The)-.275 F(router MUST)2.75 E(NO)100.8 670 Q
2.75(Ti)-.44 G(ncrease the Rate Request in the Quick-Start Request.)
-2.75 E(If the router decreases the Rate)5.5 E(Request, the router MUST\
 also modify the QS Nonce, as described in Section 3.4.)100.8 683 Q 2.75
(*I)100.8 709 S 2.75(nI)-2.75 G
(Pv4, the router MUST update the IP header checksum.)-2.75 E(Flo)72 769
Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.3. [P)2.75 F
(age 19])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E(If the router appro)100.8 85 Q
-.165(ve)-.165 G 2.75(st).165 G(he Quick-Start request, this appro)-2.75
E -.275(va)-.165 G 2.75(lS).275 G(HOULD be tak)-2.75 E(en into)-.11 E
(account in the router')100.8 98 Q 2.75(sd)-.605 G
(ecision to accept or reject subsequent Quick-Start requests \(e.g.,)
-2.75 E(using a v)100.8 111 Q(ariable that tracks the recent aggre)-.275
E -.055(ga)-.165 G(te of accepted Quick-Start requests\).).055 E(This)
5.5 E(consideration of earlier appro)100.8 124 Q -.165(ve)-.165 G 2.75
(dQ).165 G(uick-Start request is necessary to ensure that the router)
-2.75 E(only appro)100.8 137 Q -.165(ve)-.165 G 2.75(saQ).165 G(uick-St\
art request when the router judges that the output link will remain)
-2.75 E(underutilized if this and earlier Quick-Start requests are used\
 by the senders.)100.8 150 Q(In addition, the appro)100.8 176 Q -.275
(va)-.165 G 2.75(lo).275 G 2.75(faQ)-2.75 G
(uick-Start request SHOULD NO)-2.75 E 2.75(Tb)-.44 G 2.75(eu)-2.75 G
(sed by the router to)-2.75 E(af)100.8 189 Q
(fect the treatment of the data pack)-.275 E(ets that arri)-.11 E .33
-.165(ve f)-.275 H(rom this connection in the ne).165 E(xt fe)-.165 E(w)
-.275 E(round-trip times.)100.8 202 Q(That is, the appro)5.5 E -.275(va)
-.165 G 2.75(lb).275 G 2.75(yt)-2.75 G
(he router of a Quick-Start request does not gi)-2.75 E -.165(ve)-.275 G
(dif)100.8 215 Q(ferential treatment for Quick-Start data pack)-.275 E
(ets at that router; it is only a statement from)-.11 E
(the router that the router belie)100.8 228 Q -.165(ve)-.275 G 2.75(st)
.165 G(hat the subsequent Quick-Start data pack)-2.75 E(ets from this)
-.11 E(connection will not change the current under)100.8 241 Q
(-utilized state of the router)-.22 E(.)-.605 E 2.75(An)100.8 267 S
(on-participating router forw)-2.75 E
(ards the Quick-Start Request unchanged, without)-.11 E
(decrementing the QS TTL.)100.8 280 Q
(The non-participating router still decrements the TTL \214eld in)5.5 E
(the IP header)100.8 293 Q 2.75(,a)-.44 G 2.75(si)-2.75 G 2.75(sr)-2.75
G(equired for all routers [RFC1812].)-2.75 E
(As a result, the sender will be able)5.5 E(to detect that the Quick-St\
art Request had not been understood or appro)100.8 306 Q -.165(ve)-.165
G 2.75(db).165 G 2.75(ya)-2.75 G(ll of the)-2.75 E
(routers along the path.)100.8 319 Q 2.75(Ar)100.8 345 S
(outer that uses multipath routing for pack)-2.75 E
(ets within a single connection MUST NO)-.11 E(T)-.44 E(appro)100.8 358
Q .33 -.165(ve a Q)-.165 H(uick-Start request.).165 E
(This is discussed in more detail in Section 9.2.)5.5 E/F1 11
/Times-Bold@0 SF 2.75(3.3.1. Pr)72 397 R(ocessing the Report of A)-.198
E(ppr)-.275 E -.11(ove)-.198 G 2.75(dR).11 G(ate)-2.75 E F0(If the Quic\
k-Start Option has the Function \214eld set to "1000", then this is a R\
eport of)100.8 423 Q(Appro)100.8 436 Q -.165(ve)-.165 G 2.75(dR).165 G
(ate, rather than a Rate Request.)-2.75 E(The router MA)5.5 E 2.75(Yi)
-1.155 G(gnore such an option, and in)-2.75 E(an)100.8 449 Q 2.75(yc)
-.165 G(ase it MUST NO)-2.75 E 2.75(Tm)-.44 G
(odify the contents of the option for a Report of Appro)-2.75 E -.165
(ve)-.165 G 2.75(dR).165 G(ate.)-2.75 E(Ho)100.8 462 Q(we)-.275 E -.165
(ve)-.275 G .88 -.44(r, t).165 H(he router MA).44 E 2.75(Yu)-1.155 G
(se the Appro)-2.75 E -.165(ve)-.165 G 2.75(dR).165 G
(ate report to check that the sender is not)-2.75 E
(lying about the appro)100.8 475 Q -.165(ve)-.165 G 2.75(dr).165 G 2.75
(ate. If)-2.75 F(the reported Appro)2.75 E -.165(ve)-.165 G 2.75(dR).165
G(ate is higher than the rate that the)-2.75 E(router actually appro)
100.8 488 Q -.165(ve)-.165 G 2.75(df).165 G
(or this connection in the pre)-2.75 E
(vious round-trip time, then the router)-.275 E
(may implement some polic)100.8 501 Q 2.75(yf)-.165 G(or cheaters.)-2.75
E -.165(Fo)5.5 G 2.75(ri).165 G(nstance, the router MA)-2.75 E 2.75(Yd)
-1.155 G(ecide to den)-2.75 E(y)-.165 E
(future Quick-Start requests from this sender)100.8 514 Q 2.75(,i)-.44 G
(ncluding, if desired, deleting Quick-Start)-2.75 E
(requests from future pack)100.8 527 Q(ets from this sender)-.11 E 5.5
(.S)-.605 G(ection 9.4.1 discusses misbeha)-5.5 E(ving senders)-.22 E
(in more detail.)100.8 540 Q(From the Report of Appro)5.5 E -.165(ve)
-.165 G 2.75(dR).165 G(ate, the router can also learn if some of the)
-2.75 E(do)100.8 553 Q(wnstream routers ha)-.275 E .33 -.165(ve a)-.22 H
(ppro).165 E -.165(ve)-.165 G 2.75(dt).165 G
(he Quick-Start request for a smaller rate or denied the)-2.75 E
(use of Quick-Start, and adjust its bandwidth allocations accordingly)
100.8 566 Q(.)-.715 E F1(3.4.)72 605 Q/F2 13/Times-Bold@0 SF
(The QS Nonce)5.5 E F0(The QS Nonce gi)100.8 631 Q -.165(ve)-.275 G 2.75
(st).165 G(he Quick-Start sender some protection ag)-2.75 E(ainst recei)
-.055 E -.165(ve)-.275 G(rs lying about).165 E(the v)100.8 644 Q
(alue of the recei)-.275 E -.165(ve)-.275 G 2.75(dR).165 G(ate Request.)
-2.75 E(This is particularly important if the recei)5.5 E -.165(ve)-.275
G 2.75(rk).165 G(no)-2.75 E(ws)-.275 E(the original v)100.8 657 Q
(alue of the Rate Request \(e.g., when the sender al)-.275 E -.11(wa)
-.11 G(ys requests the same).11 E -.275(va)100.8 670 S
(lue, and the recei).275 E -.165(ve)-.275 G 2.75(rh).165 G
(as a long history of communication with that sender\).)-2.75 E -.44(Wi)
5.5 G(thout the).44 E(QS Nonce, there is nothing to pre)100.8 683 Q
-.165(ve)-.275 G(nt the recei).165 E -.165(ve)-.275 G 2.75(rf).165 G
(rom reporting back to the sender a Rate)-2.75 E
(Request of K, when the recei)100.8 696 Q -.165(ve)-.275 G 2.75(dR).165
G(ate Request w)-2.75 E(as in f)-.11 E(act less than K.)-.11 E -.88(Ta)
100.8 722 S(ble 2 gi).88 E -.165(ve)-.275 G 2.75(st).165 G
(he format for the 30-bit QS Nonce.)-2.75 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.4. [P)2.75 F(age 20])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E/F1 11/Courier@0 SF 52.8
(Bits Purpose)100.8 85 R 19.8(--------- ------------------)100.8 98 R
(Bits 0-1:)100.8 111 Q(Rate 15 -> Rate 14)26.4 E(Bits 2-3:)100.8 124 Q
(Rate 14 -> Rate 13)26.4 E(Bits 4-5:)100.8 137 Q(Rate 13 -> Rate 12)26.4
E(Bits 6-7:)100.8 150 Q(Rate 12 -> Rate 11)26.4 E(Bits 8-9:)100.8 163 Q
(Rate 11 -> Rate 10)26.4 E(Bits 10-11:)100.8 176 Q(Rate 10 -> Rate 9)
13.2 E(Bits 12-13:)100.8 189 Q(Rate 9 -> Rate 8)13.2 E(Bits 14-15:)100.8
202 Q(Rate 8 -> Rate 7)13.2 E(Bits 16-17:)100.8 215 Q(Rate 7 -> Rate 6)
13.2 E(Bits 18-19:)100.8 228 Q(Rate 6 -> Rate 5)13.2 E(Bits 20-21:)100.8
241 Q(Rate 5 -> Rate 4)13.2 E(Bits 22-23:)100.8 254 Q(Rate 4 -> Rate 3)
13.2 E(Bits 24-25:)100.8 267 Q(Rate 3 -> Rate 2)13.2 E(Bits 26-27:)100.8
280 Q(Rate 2 -> Rate 1)13.2 E(Bits 28-29:)100.8 293 Q(Rate 1 -> Rate 0)
13.2 E(Table 2: The QS Nonce.)100.8 319 Q F0
(The transport sender MUST initialize the QS Nonce to a random v)100.8
351 Q 2.75(alue. If)-.275 F(the router)2.75 E(reduces the Rate Request \
from rate K to rate K-1, then the router MUST set the \214eld in the)
100.8 364 Q(QS Nonce for "Rate K -> Rate K-1" to a ne)100.8 377 Q 2.75
(wr)-.275 G(andom v)-2.75 E 2.75(alue. Similarly)-.275 F 2.75(,i)-.715 G
2.75(ft)-2.75 G(he router)-2.75 E(reduces the Rate Request by N steps, \
the router MUST set the 2N bits in the rele)100.8 390 Q -.275(va)-.275 G
(nt \214elds).275 E(in the QS Nonce to a ne)100.8 403 Q 2.75(wr)-.275 G
(andom v)-2.75 E 2.75(alue. The)-.275 F(recei)2.75 E -.165(ve)-.275 G
2.75(rM).165 G(UST report the QS Nonce back to)-2.75 E(the sender)100.8
416 Q(.)-.605 E(If the Rate Request w)100.8 442 Q
(as not decremented in the netw)-.11 E(ork, then the QS Nonce should ha)
-.11 E -.165(ve)-.22 G(its original v)100.8 455 Q 2.75(alue. Similarly)
-.275 F 2.75(,i)-.715 G 2.75(ft)-2.75 G(he Rate Request w)-2.75 E
(as decremented by N steps in the)-.11 E(netw)100.8 468 Q
(ork, and the recei)-.11 E -.165(ve)-.275 G 2.75(rr).165 G
(eports back a Rate Request of K, then the last 2K bits of the QS)-2.75
E(Nonce should ha)100.8 481 Q .33 -.165(ve t)-.22 H(heir original v).165
E(alue.)-.275 E -.44(Wi)100.8 507 S(th the QS Nonce, the recei).44 E
-.165(ve)-.275 G 2.75(rh).165 G
(as a 1/4 chance of cheating about each step change in the)-2.75 E
(rate request.)100.8 520 Q(Thus, if the rate request w)5.5 E
(as reduced by tw)-.11 E 2.75(os)-.11 G(teps in the netw)-2.75 E
(ork, the recei)-.11 E -.165(ve)-.275 G(r).165 E(has a 1/16 chance of s\
uccessfully reporting that the original request w)100.8 533 Q(as appro)
-.11 E -.165(ve)-.165 G(d, as this).165 E
(requires reporting the original v)100.8 546 Q(alue for the QS nonce.)
-.275 E(Similarly)5.5 E 2.75(,i)-.715 G 2.75(ft)-2.75 G
(he rate request is)-2.75 E(reduced man)100.8 559 Q 2.75(ys)-.165 G
(teps in the netw)-2.75 E(ork, and the recei)-.11 E -.165(ve)-.275 G
2.75(rr).165 G(ecei)-2.75 E -.165(ve)-.275 G 2.75(saQ).165 G 2.75(SO)
-2.75 G(ption with a rate)-2.75 E(request of K, the recei)100.8 572 Q
-.165(ve)-.275 G 2.75(rh).165 G
(as a 1/16 chance of guessing the original v)-2.75 E
(alues for the \214elds in)-.275 E
(the QS nonce for "Rate K+2 -> Rate K+1" and "Rate K+1 -> Rate K".)100.8
585 Q(Thus, the recei)5.5 E -.165(ve)-.275 G(r).165 E
(has a 1/16 chance in successfully lying and saying that the recei)100.8
598 Q -.165(ve)-.275 G 2.75(dr).165 G(ate request w)-2.75 E(as K+2)-.11
E(instead of K.)100.8 611 Q 1.76 -.88(We n)100.8 637 T
(ote that the protection of).88 E
(fered by the QS Nonce is the same whether one router mak)-.275 E(es)
-.11 E(all of the decrements in the rate request, or whether the)100.8
650 Q 2.75(ya)-.165 G(re made at dif)-2.75 E(ferent routers along)-.275
E(the path.)100.8 663 Q(The requirements for randomization for the send\
er and routers in setting `random' v)100.8 689 Q(alues)-.275 E
(in the QS Nonce are not stringent - almost an)100.8 702 Q 2.75(yf)-.165
G(orm of pseudo-random numbers w)-2.75 E(ould do.)-.11 E
(The requirement is that the original v)100.8 715 Q
(alue for the QS Nonce is not easily predictable by the)-.275 E(Flo)72
769 Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.4. [P)2.75
F(age 21])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(recei)100.8 85 Q -.165(ve)
-.275 G .88 -.44(r, a).165 H(nd in particular).44 E 2.75(,t)-.44 G
(he nonce MUST NO)-2.75 E 2.75(Tb)-.44 G 2.75(ee)-2.75 G
(asily determined from inspection of)-2.75 E(the rest of the pack)100.8
98 Q(et or from pre)-.11 E(vious pack)-.275 E 2.75(ets. In)-.11 F
(particular)2.75 E 2.75(,t)-.44 G(he nonce MUST NO)-2.75 E 2.75(Tb)-.44
G(e)-2.75 E(based only on a combination of speci\214c pack)100.8 111 Q
(et header \214elds.)-.11 E(Thus, if tw)5.5 E 2.75(ob)-.11 G
(its of the QS)-2.75 E
(Nonce are changed by a router along the path, the recei)100.8 124 Q
-.165(ve)-.275 G 2.75(rs).165 G(hould not be able to guess)-2.75 E
(those tw)100.8 137 Q 2.75(ob)-.11 G
(its from the other 28 bits in the QS Nonce.)-2.75 E
(An additional requirement is that the recei)100.8 163 Q -.165(ve)-.275
G 2.75(rc).165 G(annot be able to tell, from the QS Nonce)-2.75 E
(itself, which numbers in the QS Nonce were generated by the sender)
100.8 176 Q 2.75(,a)-.44 G(nd which were)-2.75 E
(generated by routers along the path.)100.8 189 Q(This mak)5.5 E
(es it harder for the recei)-.11 E -.165(ve)-.275 G 2.75(rt).165 G 2.75
(oi)-2.75 G(nfer the v)-2.75 E(alue)-.275 E
(of the original rate request, making it one step harder for the recei)
100.8 202 Q -.165(ve)-.275 G 2.75(rt).165 G 2.75(oc)-2.75 G(heat.)-2.75
E(Section 9.4 also considers issues of recei)100.8 228 Q -.165(ve)-.275
G 2.75(rc).165 G(heating in more detail.)-2.75 E/F1 11/Times-Bold@0 SF
(4.)72 267 Q/F2 14/Times-Bold@0 SF(The Quick-Start Mechanisms in TCP)5.5
E F0(This section describes ho)100.8 293 Q 2.75(wt)-.275 G
(he Quick-Start mechanism w)-2.75 E(ould be used in TCP)-.11 E 5.5(.W)
-1.221 G 2.75<658c>-6.38 G(rst)-2.75 E(sk)100.8 306 Q(etch the procedur\
e and then tightly de\214ne it in the subsequent subsections.)-.11 E
(If a TCP sender)100.8 332 Q 2.75(,s)-.44 G(ay host A, w)-2.75 E
(ould lik)-.11 E 2.75(et)-.11 G 2.75(ou)-2.75 G
(se Quick-Start, the TCP sender puts the)-2.75 E(requested sending rate\
 in bits per second, appropriately formatted, in the Quick-Start)100.8
345 Q(option in the IP header of the TCP pack)100.8 358 Q
(et, called the Quick-Start request pack)-.11 E 2.75(et. \(W)-.11 F 2.75
(ew)-.88 G(ill)-2.75 E(be some)100.8 371 Q
(what loose in our use of "pack)-.275 E(et" vs. "se)-.11 E
(gment" in this section.\))-.165 E(When used for)5.5 E
(initial start-up, the Quick-Start request pack)100.8 384 Q
(et can be either the SYN or SYN/A)-.11 E(CK pack)-.44 E(et,)-.11 E
(as illustrated in Figure 1.)100.8 397 Q
(The requested rate includes an estimate for the transport and IP)5.5 E
(header o)100.8 410 Q -.165(ve)-.165 G 2.75(rhead. The).165 F(TCP recei)
2.75 E -.165(ve)-.275 G .88 -.44(r, s).165 H
(ay host B, returns the Quick-Start Response option in).44 E
(the TCP header in the responding SYN/A)100.8 423 Q(CK pack)-.44 E
(et or A)-.11 E(CK pack)-.44 E(et, called the Quick-Start)-.11 E
(response pack)100.8 436 Q
(et, informing host A of the results of their request.)-.11 E
(If the ackno)100.8 462 Q(wledging pack)-.275 E
(et does not contain a Quick-Start Response, or contains a Quick-)-.11 E
(Start Response with the wrong v)100.8 475 Q(alue for the TTL Dif)-.275
E 2.75(fo)-.275 G 2.75(rt)-2.75 G(he QS Nonce, then host A MUST)-2.75 E
(assume that its Quick-Start request f)100.8 488 Q 2.75(ailed. In)-.11 F
(this case, host A sends a Report of Appro)2.75 E -.165(ve)-.165 G(d)
.165 E(Rate with a Rate Report of zero, and uses TCP')100.8 501 Q 2.75
(sd)-.605 G(ef)-2.75 E(ault congestion control procedure.)-.11 E -.165
(Fo)5.5 G(r).165 E(initial start-up, host A uses the def)100.8 514 Q
(ault initial congestion windo)-.11 E 2.75(w\()-.275 G
([RFC2581], [RFC3390]\).)-2.75 E(If the returning pack)100.8 540 Q
(et contains a v)-.11 E(alid Quick-Start Response, then host A uses the)
-.275 E(information in the response, along with its measurement of the \
round-trip time, to)100.8 553 Q
(determine the Quick-Start congestion windo)100.8 566 Q 2.75(w\()-.275 G
2.75(QS-cwnd\). Quick-Start)-2.75 F(data pack)2.75 E(ets are)-.11 E
(de\214ned as data pack)100.8 579 Q(ets sent as the result of a success\
ful Quick-Start request, up to the time)-.11 E
(when the \214rst Quick-Start pack)100.8 592 Q(et is ackno)-.11 E 2.75
(wledged. The)-.275 F(sender also sends a Report of)2.75 E(Appro)100.8
605 Q -.165(ve)-.165 G 2.75(dR).165 G 2.75(ate. In)-2.75 F
(order to use Quick-Start, the TCP host MUST use rate-based pacing)2.75
E([VH97] to transmit Quick-Start pack)100.8 618 Q
(ets at the rate indicated in the Quick-Start Response, at)-.11 E
(the le)100.8 631 Q -.165(ve)-.275 G 2.75(lo).165 G 2.75(fg)-2.75 G
(ranularity possible by the sending host.)-2.75 E 1.76 -.88(We n)5.5 H
(ote that the limitations of).88 E(interrupt timing on computers can li\
mit the ability of the TCP host in rate-pacing the)100.8 644 Q
(outgoing pack)100.8 657 Q(ets.)-.11 E(The tw)100.8 683 Q 2.75(oT)-.11 G
(CP end-hosts can independently decide whether to request Quick-Start.)
-2.75 E -.165(Fo)5.5 G(r).165 E -.165(ex)100.8 696 S
(ample, host A could sent a Quick-Start Request in the SYN pack).165 E
(et, and host B could also)-.11 E
(send a Quick-Start Request in the SYN/A)100.8 709 Q(CK pack)-.44 E(et.)
-.11 E(Flo)72 769 Q 212.275(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(4. [P)2.75 F(age 22])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E/F1 11/Times-Bold@0 SF(4.1.)72
85 Q/F2 13/Times-Bold@0 SF(Sending the Quick-Start Request)5.5 E F0(Whe\
n sending a Quick-Start Request, the TCP sender SHOULD send the request\
 on a)100.8 111 Q(pack)100.8 124 Q(et that requires an ackno)-.11 E
(wledgement, such as a SYN, SYN/A)-.275 E(CK, or data pack)-.44 E 2.75
(et. In)-.11 F(this case, if the pack)100.8 137 Q(et is ackno)-.11 E
(wledged b)-.275 E(ut no Quick-Start Response is included, then the)-.22
E(sender kno)100.8 150 Q(ws that the Quick-Start request has been denie\
d, and can send a Report of)-.275 E(Appro)100.8 163 Q -.165(ve)-.165 G
2.75(dR).165 G(ate.)-2.75 E(In addition to the use of Quick-Start when \
a connection is established, there are se)100.8 189 Q -.165(ve)-.275 G
(ral).165 E
(additional points in a connection when a transport protocol may w)100.8
202 Q(ant to issue a Rate)-.11 E 2.75(Request. W)100.8 215 R 2.75<658c>
-.88 G(rst re-iterate the notion that Quick-Start is a coarse-grained m\
echanism.)-2.75 E(That is, Quick-Start')100.8 228 Q 2.75(sR)-.605 G
(ate Requests are not meant to be used for \214ne-grained control of)
-2.75 E(the transport')100.8 241 Q 2.75(ss)-.605 G(ending rate.)-2.75 E
(Rather)5.5 E 2.75(,t)-.44 G(he transport MA)-2.75 E 2.75(Yi)-1.155 G
(ssue a Rate Request when no)-2.75 E
(information about the appropriate sending rate is a)100.8 254 Q -.275
(va)-.22 G(ilable and the def).275 E(ault congestion)-.11 E(control mec\
hanisms might be signi\214cantly underestimating the appropriate sendin\
g rate.)100.8 267 Q(The follo)100.8 293 Q
(wing are potential points where Quick-Start may be useful:)-.275 E(\(1\
\) At or soon after connection initiation, when the transport has no id\
ea of the)129.6 322.6 Q(capacity of the netw)129.6 335.6 Q
(ork path, as discussed abo)-.11 E -.165(ve)-.165 G 5.5(.\().165 G 2.75
(At)-5.5 G(ransport that uses TCP)-2.75 E(Control Block sharing [RFC214\
0], the Congestion Manager [RFC3124], or other)129.6 348.6 Q(mechanisms\
 for sharing congestion information may not need Quick-Start to)129.6
361.6 Q(determine an appropriate rate.\))129.6 374.6 Q
(\(2\) After an idle period when the transport no longer has a v)129.6
404.2 Q(alidated estimate of the)-.275 E -.22(av)129.6 417.2 S
(ailable bandwidth for this \215o)-.055 E 4.18 -.715(w. \()-.275 H(An e)
.715 E(xample could be a persistent-HTTP)-.165 E(connection when a ne)
129.6 430.2 Q 2.75(wH)-.275 G(TTP request is recei)-2.75 E -.165(ve)
-.275 G 2.75(da).165 G(fter an idle period.\))-2.75 E
(\(3\) After a host has recei)129.6 459.8 Q -.165(ve)-.275 G 2.75(de)
.165 G(xplicit indications that one of the endpoints has mo)-2.915 E
-.165(ve)-.165 G(d).165 E(its point of netw)129.6 472.8 Q
(ork attachment.)-.11 E(This can happen due to some underlying mobility)
5.5 E(mechanism lik)129.6 485.8 Q 2.75(eM)-.11 G
(obile IP \([RFC3344], [RFC3775]\).)-2.75 E(Some transports, such as)5.5
E(SCTP [RFC2960], may associate with multiple IP addresses and can swit\
ch)129.6 498.8 Q(addresses \(and, therefore netw)129.6 511.8 Q
(ork paths\) in mid-connection.)-.11 E(If the transport has)5.5 E
(concrete kno)129.6 524.8 Q(wledge of a changing netw)-.275 E
(ork path then the current sending rate may)-.11 E(not be appropriate a\
nd the transport sender may use Quick-Start to probe the)129.6 537.8 Q
(netw)129.6 550.8 Q(ork to see if it can send at a higher rate.)-.11 E
(\(Alternati)5.5 E -.165(ve)-.275 G(ly).165 E 2.75(,t)-.715 G
(raditional slo)-2.75 E(w-start)-.275 E
(should be used in this case when Quick-Start is not a)129.6 563.8 Q
-.275(va)-.22 G(ilable.\)).275 E(\(4\) After an application-limited per\
iod when the sender has been using only a small)129.6 593.4 Q
(amount of its appropriate share of the netw)129.6 606.4 Q(ork capacity)
-.11 E 2.75(,a)-.715 G(nd has no v)-2.75 E(alid estimate for)-.275 E
(its f)129.6 619.4 Q(air share.)-.11 E
(In this case, Quick-Start may be an appropriate mechanism to)5.5 E
(determine if the sender can send at a higher rate.)129.6 632.4 Q -.165
(Fo)5.5 G 2.75(ri).165 G(nstance, consider an)-2.75 E
(application that steadily e)129.6 645.4 Q(xchanges lo)-.165 E
(w-rate control messages and suddenly needs to)-.275 E(transmit a lar)
129.6 658.4 Q(ge amount of data.)-.198 E(Of the abo)100.8 688 Q -.165
(ve)-.165 G 2.75(,t).165 G(his document recommends that a TCP sender MA)
-2.75 E 2.75(Ya)-1.155 G(ttempt to use Quick-)-2.75 E
(Start in cases \(1\) and \(2\).)100.8 701 Q(It is NO)5.5 E 2.75(TR)-.44
G(ECOMMENDED that a TCP sender use Quick-Start)-2.75 E
(for case \(3\) at the current time.)100.8 714 Q(Case \(3\) requires e)
5.5 E(xternal noti\214cations not presently)-.165 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.1. [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 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E
(de\214ned for TCP or other transport protocols.)100.8 85 Q(Finally)5.5
E 2.75(,aT)-.715 G(CP SHOULD NO)-2.75 E 2.75(Tu)-.44 G(se Quick-)-2.75 E
(Start for case \(4\) at the current time.)100.8 98 Q
(Case \(4\) requires further thought and in)5.5 E -.165(ve)-.44 G(stig)
.165 E(ation)-.055 E(with re)100.8 111 Q -.055(ga)-.165 G(rd to ho).055
E 2.75(wt)-.275 G(he transport protocol could determine it w)-2.75 E
(as in a situation that w)-.11 E(ould)-.11 E -.11(wa)100.8 124 S
(rrant transmitting a Quick-Start Request.).11 E
(As a general guideline, a TCP sender SHOULD NO)100.8 150 Q 2.75(Tr)-.44
G(equest a sending rate lar)-2.75 E(ger than it is)-.198 E
(able to use o)100.8 163 Q -.165(ve)-.165 G 2.75(rt).165 G(he ne)-2.75 E
(xt round-trip time of the connection \(or o)-.165 E -.165(ve)-.165 G
2.75(r1).165 G(00 ms, if the round-)-2.75 E(trip time is not kno)100.8
176 Q(wn\), e)-.275 E
(xcept as required to round up the desired sending rate to the ne)-.165
E(xt-)-.165 E(highest allo)100.8 189 Q -.11(wa)-.275 G(ble request.).11
E(In an)100.8 215 Q 2.75(yc)-.165 G(ircumstances, the sender MUST NO)
-2.75 E 2.75(Tm)-.44 G(ak)-2.75 E 2.75(eaQ)-.11 G 2.75(Sr)-2.75 G
(equest if it has made a QS)-2.75 E
(request within the most recent round-trip time.)100.8 228 Q(Section 4.\
7 discusses some of the issues of using Quick-Start at connection initi\
ation, and)100.8 254 Q(Section 4.8 discusses issues that arise when Qui\
ck-Start is used to request a lar)100.8 267 Q(ger sending)-.198 E
(rate after an idle period.)100.8 280 Q/F1 11/Times-Bold@0 SF(4.2.)72
319 Q/F2 13/Times-Bold@0 SF
(The Quick-Start Response Option in the TCP header)5.5 E F0
(In order to appro)100.8 345 Q .33 -.165(ve t)-.165 H
(he use of Quick-Start, the TCP recei).165 E -.165(ve)-.275 G 2.75(rr)
.165 G(esponds to the receipt of a)-2.75 E(Quick-Start Request with a Q\
uick-Start Response, using the Quick-Start Response Option)100.8 358 Q
(in the TCP header)100.8 371 Q 5.5(.T)-.605 G(CP')-5.5 E 2.75(sQ)-.605 G
(uick-Start Response option is de\214ned as follo)-2.75 E(ws:)-.275 E/F3
11/Courier@0 SF 125.4(0123)107.4 416 S 6.6
(01234567890123456789012345678901)107.4 429 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
442 Q 33(|K)100.8 455 S 33(ind |)-33 F 26.4(Length=8 |)13.2 F
(Resv. | Rate)6.6 E 19.8(|T)13.2 G(TL Diff)-19.8 E(|)26.4 E 99(|||)100.8
468 S 92.4(|Request| |)-52.8 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
481 Q 125.4(|Q)100.8 494 S 6.6(SN)-125.4 G 204.6(once |)-6.6 F 6.6(R|)
6.6 G(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)
100.8 507 Q(Figure 5.)120.6 533 Q
(The Quick-Start Response option in the TCP header.)13.2 E F0(The \214r\
st byte of the Quick-Start Response option contains the option kind, id\
entifying the)100.8 565 Q(TCP option \(to be assigned by IAN)100.8 578 Q
(A\).)-.385 E(The second byte of the Quick-Start Response option contai\
ns the option length in bytes.)100.8 604 Q
(The length \214eld MUST be set to 8 bytes.)100.8 617 Q
(The third byte of the Quick-Start Response option contains a four)100.8
643 Q(-bit Reserv)-.22 E(ed \214eld, and)-.165 E(the four)100.8 656 Q
(-bit allo)-.22 E
(wed Rate Request, formatted as in the Quick-Start Rate Request option.)
-.275 E(The fourth byte of the TCP option contains the TTL Dif)100.8 682
Q 2.75(f. The)-.275 F(TTL Dif)2.75 E 2.75(fc)-.275 G(ontains the)-2.75 E
(dif)100.8 695 Q
(ference between the IP TTL and QS TTL \214elds in the recei)-.275 E
-.165(ve)-.275 G 2.75(dQ).165 G(uick-Start request)-2.75 E(pack)100.8
708 Q(et, as calculated in equations \(1\) or \(2\) \(depending on whet\
her IPv4 or IPv6 is used\).)-.11 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.2. [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 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E
(Bytes 5-8 of the TCP option contain the 30-bit QS Nonce and a tw)100.8
85 Q(o-bit Reserv)-.11 E(ed \214eld.)-.165 E 1.76 -.88(We n)100.8 111 T
(ote that while there are limitations on the potential size of the Quic\
k-Start Response).88 E(Option, a Quick-Start Response Option of eight b\
ytes should not be a problem.)100.8 124 Q(The TCP)5.5 E
(Options \214eld can contain up to 40 bytes.)100.8 137 Q
(Other TCP options that might be used in a SYN)5.5 E(or SYN/A)100.8 150
Q(CK pack)-.44 E(et include Maximum Se)-.11 E
(gment Size \(four bytes\), T)-.165 E(ime Stamp \(ten)-.385 E
(bytes\), W)100.8 163 Q(indo)-.44 E 2.75(wS)-.275 G
(cale \(three bytes\), and Selecti)-2.75 E .33 -.165(ve A)-.275 H(ckno)
.165 E(wledgments Permitted \(tw)-.275 E(o)-.11 E(bytes\).)100.8 176 Q
/F1 11/Times-Bold@0 SF(4.3.)72 215 Q/F2 13/Times-Bold@0 SF
(TCP: Sending the Quick-Start Response)5.5 E F0
(An end host, say host B, that recei)100.8 241 Q -.165(ve)-.275 G 2.75
(sa).165 G 2.75(nI)-2.75 G 2.75(Pp)-2.75 G(ack)-2.75 E
(et containing a Quick-Start Request passes)-.11 E
(the Quick-Start Request, along with the v)100.8 254 Q
(alue in the IP TTL \214eld, to the recei)-.275 E(ving TCP)-.275 E
(layer)100.8 267 Q(.)-.605 E(If the TCP host is willing to permit the Q\
uick-Start Request, then a Quick-Start Response)100.8 293 Q
(option is included in the TCP header of the corresponding ackno)100.8
306 Q(wledgement pack)-.275 E 2.75(et. The)-.11 F
(Rate Request in the Quick-Start Response option is set to the recei)
100.8 319 Q -.165(ve)-.275 G 2.75(dv).165 G(alue of the Rate)-3.025 E
(Request in the Quick-Start option, or to a lo)100.8 332 Q(wer v)-.275 E
(alue if the TCP recei)-.275 E -.165(ve)-.275 G 2.75(ri).165 G 2.75(so)
-2.75 G(nly willing to)-2.75 E(allo)100.8 345 Q 2.75(wal)-.275 G -.275
(ow)-2.75 G(er Rate Request.).275 E(The TTL Dif)5.5 E 2.75(fi)-.275 G
2.75(nt)-2.75 G(he Quick-Start Response is set to the)-2.75 E(dif)100.8
358 Q(ference between the IP TTL v)-.275 E(alue and the QS TTL v)-.275 E
(alue as gi)-.275 E -.165(ve)-.275 G 2.75(ni).165 G 2.75(ne)-2.75 G
(quation \(1\) or \(2\))-2.75 E
(\(depending on whether IPv4 or IPv6 is used\).)100.8 371 Q
(The QS Nonce in the Response is set to the)5.5 E(recei)100.8 384 Q
-.165(ve)-.275 G 2.75(dv).165 G
(alue of the QS Nonce in the Quick-Start option.)-3.025 E
(If an end host recei)100.8 410 Q -.165(ve)-.275 G 2.75(sa).165 G 2.75
(nI)-2.75 G 2.75(Pp)-2.75 G(ack)-2.75 E
(et with a Quick-Start Request with a rate request of zero,)-.11 E
(then that host SHOULD NO)100.8 423 Q 2.75(Ts)-.44 G
(end a Quick-Start Response.)-2.75 E(The Quick-Start Response MUST NO)
100.8 449 Q 2.75(Tb)-.44 G 2.75(er)-2.75 G
(esent if it is lost in the netw)-2.75 E(ork. P)-.11 E(ack)-.165 E
(et loss)-.11 E(could be an indication of congestion on the return path\
, in which case it is better not to)100.8 462 Q(appro)100.8 475 Q .33
-.165(ve t)-.165 H(he Quick-Start Request.).165 E F1(4.4.)72 514 Q F2
(TCP: Recei)5.5 E(ving and Using the Quick-Start Response P)-.13 E(ack)
-.13 E(et)-.13 E F0 2.75(AT)100.8 540 S
(CP host, say TCP host A, that sent a Quick-Start Request and recei)
-2.75 E -.165(ve)-.275 G 2.75(saQ).165 G(uick-Start)-2.75 E
(Response in an ackno)100.8 553 Q
(wledgement \214rst checks that the Quick-Start Response is v)-.275 E
2.75(alid. The)-.275 F(Quick-Start Response is v)100.8 566 Q
(alid if it contains the correct v)-.275 E(alue for the TTL Dif)-.275 E
(f, and an equal)-.275 E(or lesser v)100.8 579 Q(alue for the Rate Requ\
est than that transmitted in the Quick-Start Request.)-.275 E(In)5.5 E
(addition, if the recei)100.8 592 Q -.165(ve)-.275 G 2.75(dR).165 G
(ate Request is K, then the rightmost 2K bits of the QS Nonce)-2.75 E
(must match those bits in the QS Nonce sent in the Quick-Start Request.)
100.8 605 Q(If these checks are)5.5 E
(not successful, then the Quick-Start request f)100.8 618 Q
(ailed, and the TCP host MUST use the def)-.11 E(ault)-.11 E
(TCP congestion windo)100.8 631 Q 2.75(wt)-.275 G(hat it w)-2.75 E
(ould ha)-.11 E .33 -.165(ve u)-.22 H(sed without Quick-Start.).165 E
(If the rightmost 2K)5.5 E(bits of the QS Nonce do not match those bits\
 in the QS Nonce sent in the Quick-Start)100.8 644 Q
(Request, for a recei)100.8 657 Q -.165(ve)-.275 G 2.75(dR).165 G
(ate Request of K, then the TCP host MUST NO)-2.75 E 2.75(Ts)-.44 G
(end additional)-2.75 E
(Quick-Start requests during the life of the connection.)100.8 670 Q
(Whether the Quick-Start request)5.5 E -.11(wa)100.8 683 S 2.75(ss).11 G
(uccessful or not, the host recei)-2.75 E
(ving the Quick-Start Response MUST send a Report of)-.275 E(Appro)100.8
696 Q -.165(ve)-.165 G 2.75(dR).165 G 2.75(ate. Similarly)-2.75 F 2.75
(,i)-.715 G 2.75(ft)-2.75 G(he pack)-2.75 E
(et containing the Quick-Start Request is)-.11 E(ackno)100.8 709 Q
(wledged, b)-.275 E(ut the ackno)-.22 E
(wledgement does not include a Quick-Start Response, then)-.275 E
(the sender MUST send a Report of Appro)100.8 722 Q -.165(ve)-.165 G
2.75(dR).165 G(ate.)-2.75 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.4. [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 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E(If the checks of the TTL Dif)
100.8 85 Q 2.75(fa)-.275 G
(nd the Rate Request are successful, and the TCP host is)-2.75 E(going \
to use the Quick-Start Request, it MUST start using it within one round\
-trip time of)100.8 98 Q(recei)100.8 111 Q
(ving the Quick-Start Response, or within three seconds, whiche)-.275 E
-.165(ve)-.275 G 2.75(ri).165 G 2.75(ss)-2.75 G(maller)-2.75 E 5.5(.T)
-.605 G 2.75(ou)-6.38 G(se)-2.75 E(the Quick-Start Request, the host se\
ts its Quick-Start congestion windo)100.8 124 Q 2.75(w\()-.275 G
(in terms of MSS-)-2.75 E(sized se)100.8 137 Q
(gments\), QS-cwnd, as follo)-.165 E(ws:)-.275 E
(QS-cwnd = \(R * T\) / \(MSS + H\))100.8 163 Q(\(3\))88 E(where R the R\
ate Request in bytes per second, T the measured round-trip time in seco\
nds,)100.8 189 Q
(and H the estimated TCP/IP header size in bytes \(e.g., 40 bytes\).)
100.8 202 Q(Deri)100.8 228 Q -.275(va)-.275 G(tion: the sender is allo)
.275 E(wed to transmit at R bytes per second including pack)-.275 E(et)
-.11 E(headers, b)100.8 241 Q
(ut only R*MSS/\(MSS+H\) bytes per second, or equi)-.22 E -.275(va)-.275
G(lently R*T*MSS/\(MSS+H\)).275 E
(bytes per round-trip time, of application data.)100.8 254 Q
(The TCP host SHOULD set its congestion windo)100.8 280 Q 2.75(wc)-.275
G(wnd to QS-cwnd only if QS-cwnd is)-2.75 E
(greater than cwnd; otherwise QS-cwnd is ignored.)100.8 293 Q
(If QS-cwnd is used, the TCP host sets a)5.5 E(\215ag that it is in Qui\
ck-Start mode, and while in Quick-Start mode the TCP sender MUST)100.8
306 Q(use rate-based pacing to pace out Quick-Start pack)100.8 319 Q
(ets at the appro)-.11 E -.165(ve)-.165 G 2.75(dr).165 G 2.75(ate. If,)
-2.75 F(during)2.75 E(Quick-Start mode, the TCP sender recei)100.8 332 Q
-.165(ve)-.275 G 2.75(sA).165 G(CKs for pack)-3.19 E
(ets sent before this Quick-Start)-.11 E(mode w)100.8 345 Q
(as entered, these A)-.11 E(CKs are processed as usual, follo)-.44 E
(wing the def)-.275 E(ault congestion)-.11 E(control mechanisms.)100.8
358 Q(Quick-Start mode ends when the TCP host recei)5.5 E -.165(ve)-.275
G 2.75(sa).165 G 2.75(nA)-2.75 G(CK for one)-3.19 E
(of the Quick-Start pack)100.8 371 Q(ets.)-.11 E
(If the congestion windo)100.8 397 Q 2.75(wh)-.275 G
(as not been fully used when the \214rst ack arri)-2.75 E -.165(ve)-.275
G 2.75(se).165 G(nding the)-2.75 E
(Quick-Start mode, then the congestion windo)100.8 410 Q 2.75(wi)-.275 G
2.75(sd)-2.75 G(ecreased to the amount that has actually)-2.75 E
(been used so f)100.8 423 Q(ar)-.11 E 5.5(.T)-.605 G
(his is necessary because when the Quick-Start Response is recei)-5.5 E
-.165(ve)-.275 G(d, the).165 E(TCP sender')100.8 436 Q 2.75(sr)-.605 G
(ound-trip-time estimate might be longer than for succeeding round-trip)
-2.75 E(times, e.g., because of delays at routers processing the IP Qui\
ck-Start option, or because of)100.8 449 Q(delays at the recei)100.8 462
Q -.165(ve)-.275 G 2.75(ri).165 G 2.75(nr)-2.75 G
(esponding to the Quick-Start Request pack)-2.75 E 2.75(et. In)-.11 F
(this case, an)2.75 E -.165(ove)100.8 475 S(rly-lar).165 E
(ge round-trip-time estimate could ha)-.198 E .33 -.165(ve c)-.22 H
(aused the TCP sender to translate the).165 E(appro)100.8 488 Q -.165
(ve)-.165 G 2.75(dQ).165 G
(uick-Start sending rate in bytes per second into a congestion windo)
-2.75 E 2.75(wt)-.275 G(hat is)-2.75 E(lar)100.8 501 Q
(ger than needed, with the TCP sender recei)-.198 E(ving an A)-.275 E
(CK for the \214rst Quick-Start pack)-.44 E(et)-.11 E
(before the entire congestion windo)100.8 514 Q 2.75(wh)-.275 G
(as been used.)-2.75 E(Thus, when the TCP sender recei)5.5 E -.165(ve)
-.275 G(s).165 E(the \214rst A)100.8 527 Q(CK for a Quick-Start pack)
-.44 E(et, the sender MUST reduce the congestion windo)-.11 E 2.75(wt)
-.275 G(o)-2.75 E(the amount that has actually been used.)100.8 540 Q
(As an e)100.8 566 Q(xample, a TCP sender with an appro)-.165 E -.165
(ve)-.165 G 2.75(dQ).165 G(uick-Start request of R KBps, B-byte)-2.75 E
(pack)100.8 579 Q(ets including headers, and an R)-.11 E
(TT estimate of T seconds, w)-.66 E(ould translate the Rate)-.11 E
(Request of R KBps to a congestion windo)100.8 592 Q 2.75(wo)-.275 G
2.75(fR)-2.75 G(*T/B pack)-2.75 E 2.75(ets. The)-.11 F(TCP sender w)2.75
E(ould)-.11 E(send the Quick-Start pack)100.8 605 Q
(ets rate-paced at R KBps.)-.11 E(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G
.88 -.44(r, i).165 H 2.75(ft).44 G(he actual current round-)-2.75 E
(trip time w)100.8 618 Q
(as T/2 seconds instead of T seconds, then the sender w)-.11 E(ould be)
-.11 E(gin to recei)-.165 E -.165(ve)-.275 G(ackno)100.8 631 Q
(wledgements for Quick-Start pack)-.275 E(ets after T/2 seconds.)-.11 E
-.165(Fo)5.5 G(llo).165 E(wing the paragraph)-.275 E(abo)100.8 644 Q
-.165(ve)-.165 G 2.75(,t).165 G(he TCP sender w)-2.75 E
(ould then reduce its congestion windo)-.11 E 2.75(wf)-.275 G
(rom R*T/B to)-2.75 E(approximately R*T/\(B*2\) pack)100.8 657 Q
(ets, the actual number of pack)-.11 E
(ets that were needed to \214ll the)-.11 E
(pipe at a sending rate of R KBps.)100.8 670 Q
(\(Note: this is just an illustration and that the congestion)5.5 E
(windo)100.8 683 Q 2.75(wi)-.275 G 2.75(sa)-2.75 G
(ctually set to the amount of data sent before the A)-2.75 E(CK arri)
-.44 E -.165(ve)-.275 G 2.75(sa).165 G(nd not based on)-2.75 E
(equations abo)100.8 696 Q -.165(ve)-.165 G(.\)).165 E
(After Quick-Start mode is e)100.8 722 Q(xited and the congestion windo)
-.165 E 2.75(wa)-.275 G(djusted if necessary)-2.75 E 2.75(,t)-.715 G
(he TCP)-2.75 E(Flo)72 769 Q 204.025(yd/Allman/Jain/Sarolahti Section)
-.11 F 2.75(4.4. [P)2.75 F(age 26])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
(sender returns to using the def)100.8 85 Q
(ault congestion control mechanisms, processing further)-.11 E
(incoming A)100.8 98 Q(CK pack)-.44 E
(ets as speci\214ed by those congestion control mechanisms.)-.11 E -.165
(Fo)5.5 G(r).165 E -.165(ex)100.8 111 S(ample, if the TCP sender w).165
E(as in slo)-.11 E(w-start prior to the Quick-Start request, and no)
-.275 E(pack)100.8 124 Q(ets were lost or mark)-.11 E
(ed since that time, then the sender continues in slo)-.11 E
(w-start after)-.275 E -.165(ex)100.8 137 S
(iting Quick-Start mode, as allo).165 E(wed by ssthresh.)-.275 E 1.76
-.88(To a)100.8 163 T(dd rob).88 E
(ustness, the TCP sender MUST use Limited Slo)-.22 E
(w-Start [RFC3742] along with)-.275 E 2.75(Quick-Start. W)100.8 176 R
(ith Limited Slo)-.44 E
(w-Start, the TCP sender limits the number of pack)-.275 E(ets by)-.11 E
(which the congestion windo)100.8 189 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.)-.275 E
(When Quick-Start is used at the be)100.8 215 Q
(ginning of a connection, before an)-.165 E 2.75(yp)-.165 G(ack)-2.75 E
(et marks or)-.11 E(losses ha)100.8 228 Q .33 -.165(ve b)-.22 H
(een reported, the TCP host MA).165 E 2.75(Yu)-1.155 G
(se the reported Rate Request to set the)-2.75 E(slo)100.8 241 Q
(w-start threshold to a desired v)-.275 E
(alue, e.g., to some small multiple of the congestion)-.275 E(windo)
100.8 254 Q 4.18 -.715(w. A)-.275 H
(possible future research topic is ho)3.465 E 2.75(wt)-.275 G
(he sender might modify the sho)-2.75 E(w-start)-.275 E
(threshold at the be)100.8 267 Q(ginning of a connection to a)-.165 E
-.22(vo)-.22 G(id o).22 E -.165(ve)-.165 G(rshooting the path capacity)
.165 E 5.5(.\()-.715 G(The)-5.5 E(initial v)100.8 280 Q
(alue of ssthresh is allo)-.275 E
(wed to be arbitrarily high, and some TCP implementations)-.275 E
(use the size of the adv)100.8 293 Q(ertised windo)-.165 E 2.75(wf)-.275
G(or ssthresh [RFC2581].\))-2.75 E/F1 11/Times-Bold@0 SF(4.5.)72 332 Q
/F2 13/Times-Bold@0 SF(TCP: Contr)5.5 E(olling Ackno)-.234 E
(wledgement T)-.13 E(raf\214c on the Re)-.962 E -.13(ve)-.195 G(rse P)
.13 E(ath)-.13 E F0(When a Quick-Start Request is appro)100.8 358 Q
-.165(ve)-.165 G 2.75(df).165 G(or a TCP sender)-2.75 E 2.75(,t)-.44 G
(he resulting Quick-Start data)-2.75 E(traf)100.8 371 Q
(\214c can result in a sudden increase in traf)-.275 E(\214c for pure A)
-.275 E(CK pack)-.44 E(ets on the re)-.11 E -.165(ve)-.275 G(rse path.)
.165 E -.165(Fo)100.8 384 S 2.75(re).165 G(xample, for the lar)-2.915 E
(gest Quick-Start request of 1.3 Gbps, gi)-.198 E -.165(ve)-.275 G 2.75
(naT).165 G(CP sender with)-2.75 E(1500-byte pack)100.8 397 Q
(ets and a TCP recei)-.11 E -.165(ve)-.275 G 2.75(rw).165 G
(ith delayed ackno)-2.75 E(wledgements acking e)-.275 E -.165(ve)-.275 G
(ry other).165 E(pack)100.8 410 Q
(et, this could result in 17.3 Mbps of ackno)-.11 E(wledgement traf)
-.275 E(\214c on the re)-.275 E -.165(ve)-.275 G(rse path.).165 E
(One possibility)100.8 436 Q 2.75(,i)-.715 G 2.75(nc)-2.75 G
(ases with lar)-2.75 E(ge Quick-Start requests, w)-.198 E
(ould be for TCP recei)-.11 E -.165(ve)-.275 G(rs to).165 E
(send Quick-Start requests to request bandwidth for the ackno)100.8 449
Q(wledgement traf)-.275 E(\214c on the)-.275 E(re)100.8 462 Q -.165(ve)
-.275 G(rse path.).165 E(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44
(r, i).165 H 2.75(no).44 G(ur vie)-2.75 E 1.43 -.715(w, a b)-.275 H
(etter approach w).715 E(ould be for TCP recei)-.11 E -.165(ve)-.275 G
(rs to).165 E(simply control the rate of sending ackno)100.8 475 Q
(wledgement traf)-.275 E 2.75(\214c. The)-.275 F
(optimal future solution)2.75 E -.11(wo)100.8 488 S(uld in).11 E -.22
(vo)-.44 G(lv).22 E 2.75(et)-.165 G(he e)-2.75 E
(xplicit use of congestion control for TCP ackno)-.165 E
(wledgement traf)-.275 E(\214c, as is)-.275 E(done no)100.8 501 Q 2.75
(wf)-.275 G(or the ackno)-2.75 E(wledgement traf)-.275 E(\214c in DCCP')
-.275 E 2.75(sC)-.605 G(CID2 [RFC4341].)-2.75 E
(In the absence of congestion control for ackno)100.8 527 Q
(wledgement traf)-.275 E(\214c, the TCP recei)-.275 E -.165(ve)-.275 G
2.75(rc).165 G(ould)-2.75 E(limit its sending rate for A)100.8 540 Q
(CK pack)-.44 E(ets sent in response to Quick-Start data pack)-.11 E
2.75(ets. The)-.11 F(follo)100.8 553 Q
(wing information is needed by the TCP recei)-.275 E -.165(ve)-.275 G
(r:).165 E 2.75(*T)100.8 579 S(he R)-2.75 E(TT)-.66 E 2.75(:T)-.55 G
(CP naturally measures the R)-2.75 E(TT of the path and therefore)-.66 E
(should ha)106.3 592 Q .33 -.165(ve a s)-.22 H(ample of the R).165 E(TT)
-.66 E 5.5(.I)-.814 G 2.75(ft)-5.5 G(he TCP recei)-2.75 E -.165(ve)-.275
G 2.75(rd).165 G(oes not)-2.75 E(ha)106.3 605 Q .33 -.165(ve a m)-.22 H
(easurement of the round-trip time, it can use the time).165 E
(between the receipt of the Quick-Start Request and the Report)106.3 618
Q(of Appro)106.3 631 Q -.165(ve)-.165 G 2.75(dR).165 G(ate.)-2.75 E 2.75
(*T)100.8 657 S(he Appro)-2.75 E -.165(ve)-.165 G 2.75(dR).165 G
(ate Request \(R\): When the TCP recei)-2.75 E -.165(ve)-.275 G 2.75(rr)
.165 G(ecei)-2.75 E -.165(ve)-.275 G 2.75(st).165 G(he)-2.75 E
(Quick-Start Response pack)106.3 670 Q(et, the recei)-.11 E -.165(ve)
-.275 G 2.75(rk).165 G(no)-2.75 E(ws the v)-.275 E(alue of the)-.275 E
(appro)106.3 683 Q -.165(ve)-.165 G 2.75(dR).165 G(ate Request.)-2.75 E
2.75(*T)100.8 709 S(he MSS: TCP adv)-2.75 E
(ertises the MSS during the initial three-w)-.165 E(ay)-.11 E(handshak)
106.3 722 Q 2.75(ea)-.11 G(nd therefore the recei)-2.75 E -.165(ve)-.275
G 2.75(rs).165 G(hould ha)-2.75 E .33 -.165(ve a)-.22 H 2.75(nu).165 G
(nderstanding)-2.75 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.5. [P)2.75 F(age 27])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(of the pack)106.3 85 Q
(et size the sender will be using.)-.11 E(If the recei)5.5 E -.165(ve)
-.275 G 2.75(rd).165 G(oes)-2.75 E(not ha)106.3 98 Q .33 -.165(ve s)-.22
H(uch an understanding or wishes to con\214rm the ne).165 E(gotiated)
-.165 E(MSS, the size of the \214rst data pack)106.3 111 Q
(et can be used.)-.11 E -.44(Wi)100.8 137 S
(th this set of information the TCP recei).44 E -.165(ve)-.275 G 2.75
(rc).165 G(an restrict its sending rate for pure)-2.75 E(ackno)100.8 150
Q(wledgment traf)-.275 E(\214c to at most 100 pure A)-.275 E(CK pack)
-.44 E(ets per R)-.11 E(TT by sending at most one)-.66 E -.44(AC)100.8
163 S 2.75(Kf).44 G(or e)-2.75 E -.165(ve)-.275 G(ry K data pack).165 E
(ets, for the A)-.11 E(CK Ratio K set to R*R)-.44 E 2.75
(TT/\(100*8*MSS\). The)-.66 F(recei)100.8 176 Q -.165(ve)-.275 G 2.75
(rw).165 G(ould ackno)-2.86 E(wledge the \214rst Quick-Start data pack)
-.275 E(et, and e)-.11 E -.165(ve)-.275 G(ry succeeding K data).165 E
(pack)100.8 189 Q 2.75(ets. Thus,)-.11 F(for a some)2.75 E(what e)-.275
E(xtreme case of R=1.3 Gbps, R)-.165 E(TT=0.2 seconds, and)-.66 E
(MSS=1500 bytes, K w)100.8 202 Q(ould be set to 216, and the recei)-.11
E -.165(ve)-.275 G 2.75(rw).165 G(ould ackno)-2.86 E(wledge e)-.275 E
-.165(ve)-.275 G(ry 216).165 E(data pack)100.8 215 Q 2.75(ets. From)-.11
F([RFC2581], the A)2.75 E(CK Ratio K should ha)-.44 E .33 -.165(ve a m)
-.22 H(inimum v).165 E(alue of tw)-.275 E(o.)-.11 E(When the A)100.8 228
Q(CK Ratio is greater than tw)-.44 E(o, and the TCP sender recei)-.11 E
-.165(ve)-.275 G 2.75(sa).165 G(ckno)-2.75 E(wledgements)-.275 E
(each ackno)100.8 241 Q(wledging more than tw)-.275 E 2.75(od)-.11 G
(ata pack)-2.75 E(ets, the TCP sender may w)-.11 E(ant to use rate-)-.11
E(based pacing to control the b)100.8 254 Q
(urstiness of its outgoing data traf)-.22 E(\214c.)-.275 E
(In the absence of e)100.8 280 Q
(xplicit congestion control mechanisms, the TCP end nodes cannot)-.165 E
(determine the pack)100.8 293 Q(et drop rate for pure ackno)-.11 E
(wledgement traf)-.275 E 2.75(\214c. This)-.275 F(is true with or)2.75 E
(without Quick-Start.)100.8 306 Q(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G
.88 -.44(r, t).165 H(he TCP recei).44 E -.165(ve)-.275 G 2.75(rc).165 G
(ould limit its increase in the sending rate)-2.75 E(for pure A)100.8
319 Q(CK pack)-.44 E
(ets by at most doubling the sending rate for pure A)-.11 E(CK pack)-.44
E(ets from one)-.11 E(round-trip time to the ne)100.8 332 Q 2.75
(xt. The)-.165 F(TCP recei)2.75 E -.165(ve)-.275 G 2.75(rw).165 G
(ould do this by halving the A)-2.86 E(CK Ratio)-.44 E
(each round-trip time.)100.8 345 Q(Note that the abo)100.8 371 Q .33
-.165(ve i)-.165 H 2.75(so).165 G
(ne particular mechanism that could be used to control the A)-2.75 E(CK)
-.44 E 2.75(stream. Future)100.8 384 R -.11(wo)2.75 G(rk that in).11 E
-.165(ve)-.44 G(stig).165 E
(ates this scheme and others in detail is encouraged.)-.055 E/F1 11
/Times-Bold@0 SF(4.6.)72 423 Q/F2 13/Times-Bold@0 SF
(TCP: Responding to a Loss of a Quick-Start P)5.5 E(ack)-.13 E(et)-.13 E
F0 -.165(Fo)100.8 449 S 2.75(rT).165 G(CP)-2.75 E 2.75(,w)-1.221 G 2.75
(eh)-2.75 G -2.475 -.22(av e)-2.75 H(de\214ned a `)2.97 E
(`Quick-Start pack)-.814 E(et')-.11 E 2.75('a)-.814 G 2.75(so)-2.75 G
(ne of the pack)-2.75 E(ets sent in the windo)-.11 E(w)-.275 E
(immediately follo)100.8 462 Q(wing a successful Quick-Start request.)
-.275 E(After detecting the loss or ECN-)5.5 E
(marking of a Quick-Start pack)100.8 475 Q(et, TCP MUST re)-.11 E -.165
(ve)-.275 G(rt to the def).165 E(ault congestion control)-.11 E
(procedures that w)100.8 488 Q(ould ha)-.11 E .33 -.165(ve b)-.22 H
(een used if the Quick-Start request had not been appro).165 E -.165(ve)
-.165 G(d.).165 E -.165(Fo)100.8 501 S 2.75(re).165 G
(xample, if Quick-Start is used for setting the initial windo)-2.915 E
1.43 -.715(w, a)-.275 H(nd a pack).715 E(et from the)-.11 E
(initial windo)100.8 514 Q 2.75(wi)-.275 G 2.75(sl)-2.75 G(ost or mark)
-2.75 E(ed, then the TCP sender MUST then slo)-.11 E(w-start with the)
-.275 E(def)100.8 527 Q(ault initial windo)-.11 E 2.75(wt)-.275 G(hat w)
-2.75 E(ould ha)-.11 E .33 -.165(ve b)-.22 H
(een used if Quick-Start had not been used.).165 E(In)5.5 E
(addition to re)100.8 540 Q -.165(ve)-.275 G(rting to the def).165 E
(ault congestion control mechanisms, the sender MUST tak)-.11 E(e)-.11 E
(into account that the Quick-Start congestion windo)100.8 553 Q 2.75(ww)
-.275 G(as too lar)-2.86 E 2.75(ge. Thus,)-.198 F(the sender)2.75 E(SHO\
ULD decrease ssthresh to at most half the number of Quick-Start pack)
100.8 566 Q(ets that were)-.11 E(successfully transmitted.)100.8 579 Q
(Section B.5 discusses possible alternati)5.5 E -.165(ve)-.275 G 2.75
(si).165 G 2.75(nr)-2.75 G(esponding to the)-2.75 E
(loss of a Quick-Start pack)100.8 592 Q(et.)-.11 E
(If a Quick-Start pack)100.8 618 Q(et is lost or ECN-mark)-.11 E
(ed, then the sender SHOULD NO)-.11 E 2.75(Tm)-.44 G(ak)-2.75 E 2.75(ef)
-.11 G(uture)-2.75 E(Quick-Start requests for this connection.)100.8 631
Q 1.76 -.88(We n)100.8 657 T(ote that ECN [RFC3168] MA).88 E 2.75(Yb)
-1.155 G 2.75(eu)-2.75 G(sed with Quick-Start.)-2.75 E(As is al)5.5 E
-.11(wa)-.11 G(ys the case with).11 E(ECN, the sender')100.8 670 Q 2.75
(sc)-.605 G(ongestion control response to an ECN-mark)-2.75 E
(ed Quick-Start pack)-.11 E(et is the)-.11 E
(same as the response to a dropped Quick-Start pack)100.8 683 Q
(et, thus re)-.11 E -.165(ve)-.275 G(rting to slo).165 E 2.75(ws)-.275 G
(tart in the)-2.75 E(case of Quick-Start pack)100.8 696 Q(ets mark)-.11
E(ed as e)-.11 E(xperiencing congestion.)-.165 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.6. [P)2.75 F(age 28])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E/F1 11/Times-Bold@0 SF(4.7.)72
85 Q/F2 13/Times-Bold@0 SF(TCP: A Quick-Start Request f)5.5 E(or a Lar)
-.325 E(ger Initial W)-.13 E(indo)-.234 E(w)-.13 E F0(Some of the issue\
s of using Quick-Start are related to the speci\214c scenario in which \
Quick-)100.8 111 Q(Start is used.)100.8 124 Q
(This section discusses the follo)5.5 E
(wing issues that arise when Quick-Start is)-.275 E
(used by TCP to request a lar)100.8 137 Q(ger initial windo)-.198 E
(w: \(1\) interactions with P)-.275 E(ath MTU Disco)-.165 E -.165(ve)
-.165 G(ry).165 E(\(PMTUD\); and \(2\) Quick-Start request pack)100.8
150 Q(ets that are discarded by middlebox)-.11 E(es.)-.165 E F1 2.75
(4.7.1. Interactions)72 189 R(with P)2.75 E(ath MTU Disco)-.11 E -.11
(ve)-.11 G(ry).11 E F0
(One issue when Quick-Start is used to request a lar)100.8 215 Q
(ge initial windo)-.198 E 2.75(wc)-.275 G(oncerns the)-2.75 E
(interactions between the lar)100.8 228 Q(ge initial windo)-.198 E 2.75
(wa)-.275 G(nd P)-2.75 E(ath MTU Disco)-.165 E -.165(ve)-.165 G(ry).165
E 5.5(.S)-.715 G(ome of the issues)-5.5 E(are discussed in RFC 3390:)
100.8 241 Q("When lar)129.6 257.6 Q(ger initial windo)-.198 E
(ws are implemented along with P)-.275 E(ath MTU Disco)-.165 E -.165(ve)
-.165 G(ry).165 E([RFC1191], alternati)129.6 270.6 Q -.165(ve)-.275 G
2.75(sa).165 G(re to set the "Don')-2.75 E 2.75(tF)-.198 G
(ragment" \(DF\) bit in all se)-2.75 E(gments in)-.165 E
(the initial windo)129.6 283.6 Q 1.43 -.715(w, o)-.275 H 2.75(rt).715 G
2.75(os)-2.75 G(et the "Don')-2.75 E 2.75(tF)-.198 G
(ragment" \(DF\) bit in one of the se)-2.75 E 2.75(gments. It)-.165 F
(is an open question as to which of these tw)129.6 296.6 Q 2.75(oa)-.11
G(lternati)-2.75 E -.165(ve)-.275 G 2.75(si).165 G 2.75(sb)-2.75 G
(est.")-2.75 E(If the sender kno)100.8 313.2 Q(ws the P)-.275 E
(ath MTU when the initial windo)-.165 E 2.75(wi)-.275 G 2.75(ss)-2.75 G
(ent \(e.g., from a PMTUD)-2.75 E(cache or from some other IETF-appro)
100.8 326.2 Q -.165(ve)-.165 G 2.75(dm).165 G
(ethod\), then the sender SHOULD use that)-2.75 E(MTU for se)100.8 339.2
Q(gments in the initial windo)-.165 E 4.18 -.715(w. U)-.275 H
(nfortunately).715 E 2.75(,t)-.715 G(he sender doesn')-2.75 E 2.75(tn)
-.198 G(ecessarily)-2.75 E(kno)100.8 352.2 Q 2.75(wt)-.275 G(he P)-2.75
E(ath MTU when it sends pack)-.165 E(ets in the initial windo)-.11 E
4.18 -.715(w. I)-.275 H 2.75(nt).715 G(his case, the sender)-2.75 E
(should be conserv)100.8 365.2 Q(ati)-.275 E .33 -.165(ve i)-.275 H 2.75
(nt).165 G(he pack)-2.75 E(et size used.)-.11 E(Sending a lar)5.5 E
(ge number of o)-.198 E -.165(ve)-.165 G(rly-lar).165 E(ge)-.198 E(pack)
100.8 378.2 Q(ets with the DF bit set is not desirable, b)-.11 E
(ut sending a lar)-.22 E(ge number of pack)-.198 E(ets that are)-.11 E
(fragmented in the netw)100.8 391.2 Q(ork can be equally undesirable.)
-.11 E(If the sender doesn')100.8 417.2 Q 2.75(tk)-.198 G(no)-2.75 E
2.75(wt)-.275 G(he P)-2.75 E(ath MTU when the initial windo)-.165 E 2.75
(wi)-.275 G 2.75(ss)-2.75 G(ent, the sender)-2.75 E(SHOULD send one lar)
100.8 430.2 Q(ge pack)-.198 E(et in the initial windo)-.11 E 2.75(ww)
-.275 G(ith the DF bit set, and send the)-2.75 E(remaining pack)100.8
443.2 Q(ets in the initial windo)-.11 E 2.75(ww)-.275 G
(ith a smaller MTU of 576 bytes \(or 1280 bytes)-2.75 E(with IPv6\).)
100.8 456.2 Q 2.75(As)100.8 482.2 S(econd possibility w)-2.75 E
(ould be for the sender to delay sending the Quick-Start Request for)
-.11 E(one round-trip time, sending the Quick-Start Request with the \
\214rst windo)100.8 495.2 Q 2.75(wo)-.275 G 2.75(fd)-2.75 G(ata while)
-2.75 E(also doing P)100.8 508.2 Q(ath MTU Disco)-.165 E -.165(ve)-.165
G(ry).165 E(.)-.715 E(The sender may be using an iterati)100.8 534.2 Q
.33 -.165(ve a)-.275 H(pproach such as P).165 E(ack)-.165 E
(etization Layer P)-.11 E(ath MTU)-.165 E(Disco)100.8 547.2 Q -.165(ve)
-.165 G(ry \(PLPMTUD\) [MH06] for P).165 E(ath MTU Disco)-.165 E -.165
(ve)-.165 G(ry).165 E 2.75(,w)-.715 G(here the sender tests)-2.75 E
(successi)100.8 560.2 Q -.165(ve)-.275 G(ly lar).165 E(ger MTUs.)-.198 E
(If a probe is successfully deli)5.5 E -.165(ve)-.275 G
(red then the MTU can be raised).165 E(to re\215ect the v)100.8 573.2 Q
(alue used in that probe.)-.275 E 1.76 -.88(We w)5.5 H
(ould note that PLPMTUD does not allo).77 E 2.75(wt)-.275 G(he)-2.75 E
(sender to determine the P)100.8 586.2 Q
(ath MTU before sending the initial windo)-.165 E 2.75(wo)-.275 G 2.75
(fd)-2.75 G(ata.)-2.75 E F1 2.75(4.7.2. Quick-Start)72 625.2 R
(Request P)2.75 E(ack)-.11 E(ets that ar)-.11 E 2.75(eD)-.198 G
(iscarded by Routers or Middleboxes)-2.75 E F0(It is al)100.8 651.2 Q
-.11(wa)-.11 G(ys possible for a TCP SYN pack).11 E
(et carrying a Quick-Start request to be dropped in)-.11 E(the netw)
100.8 664.2 Q(ork due to congestion, or to be block)-.11 E
(ed due to interactions with routers or)-.11 E(middlebox)100.8 677.2 Q
(es, where a middlebox is de\214ned as an)-.165 E 2.75(yi)-.165 G
(ntermediary box performing functions)-2.75 E(apart from normal, standa\
rd functions of an IP router on the data path between a source)100.8
690.2 Q(host and destination host [RFC3234].)100.8 703.2 Q
(Measurement studies of interactions between)5.5 E
(transport protocols and middlebox)100.8 716.2 Q(es [MAF04] sho)-.165 E
2.75(wt)-.275 G(hat for 70% of the web serv)-2.75 E(ers)-.165 E(Flo)72
769 Q 195.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.7.2. [P)
2.75 F(age 29])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(in)100.8 85 Q -.165(ve)-.44 G
(stig).165 E(ated, no connection is established if the TCP SYN pack)
-.055 E(et contains an unkno)-.11 E(wn IP)-.275 E
(option \(and for 43% of the web serv)100.8 98 Q
(ers, no connection is established if the TCP SYN)-.165 E(pack)100.8 111
Q(et contains an IP T)-.11 E(imeStamp Option\).)-.385 E
(In both cases, this is presumably due to routers)5.5 E(or middlebox)
100.8 124 Q(es along that path.)-.165 E(If the TCP sender doesn')100.8
150 Q 2.75(tr)-.198 G(ecei)-2.75 E .33 -.165(ve a r)-.275 H
(esponse to the SYN or SYN/A).165 E(CK pack)-.44 E(et containing)-.11 E
(the Quick-Start Request, then the TCP sender SHOULD resend the SYN or \
SYN/A)100.8 163 Q(CK)-.44 E(pack)100.8 176 Q
(et without the Quick-Start Request.)-.11 E(Similarly)5.5 E 2.75(,i)
-.715 G 2.75(ft)-2.75 G(he TCP sender recei)-2.75 E -.165(ve)-.275 G
2.75(saT).165 G(CP reset)-2.75 E(in response to the SYN or SYN/A)100.8
189 Q(CK pack)-.44 E(et containing the Quick-Start Request, then the)
-.11 E(TCP sender SHOULD resend the SYN or SYN/A)100.8 202 Q(CK pack)
-.44 E(et without the Quick-Start)-.11 E(Request [RFC3360].)100.8 215 Q
(RFC 1122 and 2988 specify that the sender should set the initial R)
100.8 241 Q .396 -.198(TO t)-.66 H 2.75(ot).198 G(hree seconds,)-2.75 E
(though man)100.8 254 Q 2.75(yT)-.165 G
(CP implementations set the initial R)-2.75 E .396 -.198(TO t)-.66 H
2.75(oo).198 G(ne second.)-2.75 E -.165(Fo)5.5 G 2.75(raT).165 G(CP SYN)
-2.75 E(pack)100.8 267 Q(et sent with a Quick-Start request, the TCP se\
nder SHOULD use an initial R)-.11 E .396 -.198(TO o)-.66 H(f).198 E
(three seconds.)100.8 280 Q 1.76 -.88(We n)100.8 306 T
(ote that if the TCP SYN pack).88 E
(et is using the IP Quick-Start Option for a Quick-Start)-.11 E
(request, and it is also using bits in the TCP header to ne)100.8 319 Q
(gotiate ECN-capability with the)-.165 E
(TCP host at the other end, then the drop of a TCP SYN pack)100.8 332 Q
(et could be due to congestion,)-.11 E
(to a router or middlebox dropping the pack)100.8 345 Q
(et because of the IP Option, or because of a)-.11 E
(router or middlebox dropping the pack)100.8 358 Q
(et because of the information in the TCP header)-.11 E(ne)100.8 371 Q
(gotiating ECN.)-.165 E
(In this case, the sender could resend the dropped pack)5.5 E
(et without either)-.11 E(the Quick-Start or the ECN requests.)100.8 384
Q(Alternately)5.5 E 2.75(,t)-.715 G(he sender could resend the dropped)
-2.75 E(pack)100.8 397 Q(et with only the ECN request in the TCP header)
-.11 E 2.75(,r)-.44 G(esending the TCP SYN pack)-2.75 E(et)-.11 E(witho\
ut either the Quick-Start or the ECN requests if the second TCP SYN pac\
k)100.8 410 Q(et is)-.11 E 2.75(dropped. The)100.8 423 R
(second choice seems reasonable, gi)2.75 E -.165(ve)-.275 G 2.75(nt).165
G(hat a TCP SYN pack)-2.75 E(et today is)-.11 E(more lik)100.8 436 Q
(ely to be block)-.11 E(ed due to policies that discard pack)-.11 E
(ets with IP Options than due to)-.11 E(policies that discard pack)100.8
449 Q(ets with ECN requests in the TCP header [MAF04].)-.11 E/F1 11
/Times-Bold@0 SF(4.8.)72 488 Q/F2 13/Times-Bold@0 SF
(TCP: A Quick-Start Request in the Middle of a Connection)5.5 E F0
(This section discusses the follo)100.8 514 Q
(wing issues that arise when Quick-Start is used by TCP to)-.275 E
(request a lar)100.8 527 Q(ger windo)-.198 E 2.75(wi)-.275 G 2.75(nt)
-2.75 G(he middle of a connection, such as after an idle period: \(1\))
-2.75 E(determining the rate to request; \(2\) when to mak)100.8 540 Q
2.75(ear)-.11 G(equest; and \(3\) the response if Quick-)-2.75 E
(Start pack)100.8 553 Q(ets are dropped;)-.11 E
(\(1\) Determining the rate to request:)100.8 579 Q -.165(Fo)100.8 592 S
2.75(rac).165 G(onnection that has not yet had a congestion e)-2.75 E
-.165(ve)-.275 G(nt \(that is, a mark).165 E(ed or dropped)-.11 E(pack)
100.8 605 Q
(et\), the TCP sender is not restricted in the rate that it requests.)
-.11 E(As an e)5.5 E(xample, a serv)-.165 E(er)-.165 E(might w)100.8 618
Q(ait and send a Quick-Start request after a short interaction with the\
 client.)-.11 E 1.76 -.88(To u)100.8 644 T
(se a Quick-Start Request in a connection that has already e).88 E
(xperienced a congestion)-.165 E -2.365 -.275(ev e)100.8 657 T
(nt, and that has not had a recent mobility e).275 E -.165(ve)-.275 G
(nt, the TCP sender can determine the).165 E(lar)100.8 670 Q
(gest congestion windo)-.198 E 2.75(wt)-.275 G
(hat the TCP connection achie)-2.75 E -.165(ve)-.275 G 2.75(ds).165 G
(ince the last pack)-2.75 E(et drop and)-.11 E
(translate this to a sending rate to get the maximum allo)100.8 683 Q
(wed request rate.)-.275 E(If the request is)5.5 E(granted, then the se\
nder essentially restarts with its old congestion windo)100.8 696 Q 2.75
(wf)-.275 G(rom before it)-2.75 E -.11(wa)100.8 709 S 2.75(sr).11 G
(educed, for e)-2.75 E(xample during an idle period.)-.165 E(Flo)72 769
Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.8. [P)2.75 F
(age 30])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E 2.75(AQ)100.8 85 S(uick-Start\
 Request sent in the middle of a TCP connection SHOULD be sent on a dat\
a)-2.75 E(pack)100.8 98 Q(et.)-.11 E(\(2\) When to mak)100.8 124 Q 2.75
(ear)-.11 G(equest:)-2.75 E 2.75(AT)100.8 137 S(CP connection MA)-2.75 E
2.75(Ym)-1.155 G(ak)-2.75 E 2.75(eaQ)-.11 G
(uick-Start request before the connection has e)-2.75 E(xperienced)-.165
E 2.75(ac)100.8 150 S(ongestion e)-2.75 E -.165(ve)-.275 G
(nt, or after an idle period of at least one R).165 E -.198(TO)-.66 G(.)
.198 E(\(3\) Response if Quick-Start pack)100.8 176 Q(ets are dropped:)
-.11 E(If Quick-Start pack)100.8 189 Q
(ets are dropped in the middle of connection, then the sender MUST)-.11
E(re)100.8 202 Q -.165(ve)-.275 G(rt to half of the Quick-Start windo)
.165 E 1.43 -.715(w, o)-.275 H 2.75(rt).715 G 2.75(ot)-2.75 G
(he congestion windo)-2.75 E 2.75(wt)-.275 G(hat the sender)-2.75 E -.11
(wo)100.8 215 S(uld ha).11 E .33 -.165(ve u)-.22 H
(sed if the Quick-Start request had not been appro).165 E -.165(ve)-.165
G(d, whiche).165 E -.165(ve)-.275 G 2.75(ri).165 G 2.75(ss)-2.75 G
(maller)-2.75 E(.)-.605 E/F1 11/Times-Bold@0 SF(4.9.)72 254 Q/F2 13
/Times-Bold@0 SF(An Example Quick-Start Scenario with TCP)5.5 E F0
(The follo)100.8 280 Q(wing is an e)-.275 E
(xample scenario in the case when both hosts request Quick-Start for)
-.165 E(setting their initial windo)100.8 293 Q 2.75(ws. This)-.275 F
(is similar to Figures 1 and 2 in Section 2.1, e)2.75 E(xcept that it)
-.165 E(illustrates a TCP connection with both TCP hosts sending Quick-\
Start Requests.)100.8 306 Q 2.75(*T)100.8 332 S(he TCP SYN pack)-2.75 E
(et from Host A contains a Quick-Start Request in the IP header)-.11 E
(.)-.605 E 2.75(*R)100.8 358 S(outers along the forw)-2.75 E
(ard path modify the Quick-Start Request as appropriate.)-.11 E 2.75(*H)
100.8 384 S(ost B recei)-2.75 E -.165(ve)-.275 G 2.75(st).165 G
(he Quick-Start Request in the SYN pack)-2.75 E
(et, and calculates the TTL Dif)-.11 E(f.)-.275 E(If Host B appro)100.8
397 Q -.165(ve)-.165 G 2.75(st).165 G
(he Quick-Start Request, then Host B sends a Quick-Start Response in)
-2.75 E(the TCP header of the SYN/A)100.8 410 Q(CK pack)-.44 E 2.75
(et. Host)-.11 F 2.75(Ba)2.75 G(lso sends a Quick-Start Request in the)
-2.75 E(IP header of the SYN/A)100.8 423 Q(CK pack)-.44 E(et.)-.11 E
2.75(*R)100.8 449 S(outers along the re)-2.75 E -.165(ve)-.275 G
(rse path modify the Quick-Start Request as appropriate.).165 E 2.75(*H)
100.8 475 S(ost A recei)-2.75 E -.165(ve)-.275 G 2.75(st).165 G
(he Quick-Start Response in the SYN/A)-2.75 E(CK pack)-.44 E
(et, and checks the TTL)-.11 E(Dif)100.8 488 Q
(f, Rate Request, and QS Nonce for v)-.275 E(alidity)-.275 E 5.5(.I)
-.715 G 2.75(ft)-5.5 G(he)-2.75 E 2.75(ya)-.165 G(re v)-2.75 E
(alid, then Host A sets its initial)-.275 E(congestion windo)100.8 501 Q
2.75(wa)-.275 G(ppropriately)-2.75 E 2.75(,a)-.715 G
(nd sets up rate-based pacing to be used with the initial)-2.75 E(windo)
100.8 514 Q 4.18 -.715(w. I)-.275 H 2.75(ft).715 G
(he Quick-Start Response is not v)-2.75 E(alid, then Host A uses TCP')
-.275 E 2.75(sd)-.605 G(ef)-2.75 E(ault initial)-.11 E(windo)100.8 527 Q
4.18 -.715(w. I)-.275 H 2.75(ne).715 G
(ither case, Host A sends a Report of Appro)-2.75 E -.165(ve)-.165 G
2.75(dR).165 G(ate.)-2.75 E(Host A also calculates the TTL Dif)100.8 553
Q 2.75(ff)-.275 G(or the Quick-Start Request in the incoming)-2.75 E
(SYN/A)100.8 566 Q(CK pack)-.44 E
(et, and sends a Quick-Start Response in the TCP header of the A)-.11 E
(CK)-.44 E(pack)100.8 579 Q(et.)-.11 E 2.75(*H)100.8 605 S(ost B recei)
-2.75 E -.165(ve)-.275 G 2.75(st).165 G(he Quick-Start Response in an A)
-2.75 E(CK pack)-.44 E(et, and checks the TTL Dif)-.11 E(f,)-.275 E
(Rate Request, and QS Nonce for v)100.8 618 Q(alidity)-.275 E 5.5(.I)
-.715 G 2.75(ft)-5.5 G(he Quick-Start Response is v)-2.75 E
(alid, then Host B)-.275 E(sets its initial congestion windo)100.8 631 Q
2.75(wa)-.275 G(ppropriately)-2.75 E 2.75(,a)-.715 G
(nd sets up rate-based pacing to be used)-2.75 E(with its initial windo)
100.8 644 Q 4.18 -.715(w. I)-.275 H 2.75(ft).715 G
(he Quick-Start Response is not v)-2.75 E(alid, then Host B uses TCP')
-.275 E(s)-.605 E(def)100.8 657 Q(ault initial windo)-.11 E 4.18 -.715
(w. I)-.275 H 2.75(ne).715 G(ither case, Host B sends a Report of Appro)
-2.75 E -.165(ve)-.165 G 2.75(dR).165 G(ate.)-2.75 E F1(5.)72 696 Q/F3
14/Times-Bold@0 SF(Quick-Start and IPsec AH)5.5 E F0(This section sho)
100.8 722 Q(ws that Quick-Start is compatible with IPsec AH \(Authentic\
ation Header\).)-.275 E(Flo)72 769 Q 212.275
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(5. [P)2.75 F(age 31])-.165
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(April 2007)2.75 E(October 2006)112.127 E(AH uses an Inte)100.8 85 Q
(grity Check V)-.165 E
(alue \(ICV\) in the IPsec Authentication Header to v)-1.221 E
(erify both)-.165 E(message authentication and inte)100.8 98 Q
(grity \([RFC4302], page 85\).)-.165 E(Changes to the Quick-Start)5.5 E
(option in the IP header do not af)100.8 111 Q(fect this AH ICV)-.275 E
5.5(.T)-1.419 G(he tunnel considerations in Section 6)-5.5 E(belo)100.8
124 Q 2.75(wa)-.275 G(pply to all IPsec tunnels, re)-2.75 E -.055(ga)
-.165 G(rdless of what IPsec headers or processing are used in).055 E
(conjunction with the tunnel.)100.8 137 Q(Because the contents of the Q\
uick-Start option can change along the path, it is important)100.8 163 Q
(that these changes not af)100.8 176 Q
(fect the IPsec Authentication Header Inte)-.275 E(grity Check V)-.165 E
(alue \(AH)-1.221 E 2.75(ICV\). F)100.8 189 R(or IPv4, RFC 4302 require\
s that unrecognized IPv4 options be zeroed for AH ICV)-.165 E(computati\
on purposes, so Quick-Start IP Option data changing en route does not c\
ause)100.8 202 Q(problems with e)100.8 215 Q
(xisting IPsec AH implementations for IPv4.)-.165 E
(If the Quick-Start option is)5.5 E(recognized, it MUST be treated as a\
 mutable IPv4 option, and hence be completely zeroed)100.8 228 Q
(for AH ICV calculation purposes.)100.8 241 Q(IPv6 option numbers e)5.5
E(xplicitly indicate whether the)-.165 E
(option is mutable; the 3rd highest order bit in the IAN)100.8 254 Q
(A-allocated option type has the v)-.385 E(alue)-.275 E 2.75(1t)100.8
267 S 2.75(oi)-2.75 G
(ndicate that the Quick-Start option data can change en route.)-2.75 E
(RFC 4302 requires that)5.5 E(the option data of an)100.8 280 Q 2.75(ys)
-.165 G(uch option be zeroed for AH ICV computation purposes.)-2.75 E
(Therefore)5.5 E
(changes to the Quick-Start option in the IP header do not af)100.8 293
Q(fect the calculation of the AH)-.275 E(ICV)100.8 306 Q(.)-1.419 E/F1
11/Times-Bold@0 SF(6.)72 345 Q/F2 14/Times-Bold@0 SF
(Quick-Start in IP T)5.5 E(unnels and MPLS)-1.288 E F0(This section con\
siders interactions between Quick-Start and IP tunnels, including IPsec)
100.8 371 Q
(\([RFC4301]\), IP in IP [RFC2003], GRE [RFC2784], and others.)100.8 384
Q(This section also)5.5 E
(considers interactions between Quick-Start and MPLS [RFC3031].)100.8
397 Q(In the discussion, we use TTL Dif)100.8 423 Q
(f, de\214ned earlier as the dif)-.275 E(ference between the IP TTL)
-.275 E(and the Quick-Start TTL, mod 256.)100.8 436 Q
(Recall that the sender considers the Quick-Start)5.5 E(request appro)
100.8 449 Q -.165(ve)-.165 G 2.75(do).165 G(nly if the v)-2.75 E
(alue of TTL Dif)-.275 E 2.75(ff)-.275 G(or the pack)-2.75 E
(et entering the netw)-.11 E(ork is the)-.11 E(same as the v)100.8 462 Q
(alue of TTL Dif)-.275 E 2.75(ff)-.275 G(or the pack)-2.75 E(et e)-.11 E
(xiting the netw)-.165 E(ork.)-.11 E
(Simple tunnels: IP tunnel modes are generally based on adding a ne)
100.8 488 Q 2.75(w")-.275 G(outer" IP header)-2.75 E(that encapsulates \
the original or "inner" IP header and its associated pack)100.8 501 Q
2.75(et. In)-.11 F(man)2.75 E 2.75(yc)-.165 G(ases,)-2.75 E(the ne)100.8
514 Q 2.75(w")-.275 G(outer" IP header may be added and remo)-2.75 E
-.165(ve)-.165 G 2.75(da).165 G 2.75(ti)-2.75 G
(ntermediate points along a path,)-2.75 E(enabling the netw)100.8 527 Q
(ork to establish a tunnel without requiring endpoint participation.)
-.11 E -.88(We)5.5 G(denote tunnels that specify that the outer header \
be discarded at tunnel e)100.8 540 Q(gress as "simple)-.165 E
(tunnels", and we denote tunnels where the e)100.8 553 Q(gress sa)-.165
E -.165(ve)-.22 G 2.75(sa).165 G(nd uses information from the outer)
-2.75 E(header before discarding it as "non-simple tunnels".)100.8 566 Q
(An e)5.5 E(xample of a "non-simple tunnel")-.165 E -.11(wo)100.8 579 S
(uld be a tunnel con\214gured to support ECN, where the e).11 E
(gress router might cop)-.165 E 2.75(yt)-.11 G(he ECN)-2.75 E(codepoint\
 in the outer header to the inner header before discarding the outer he\
ader)100.8 592 Q([RFC3168].)100.8 605 Q(Flo)72 769 Q 212.275
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(6. [P)2.75 F(age 32])-.165
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(April 2007)2.75 E(October 2006)112.127 E/F1 11/Courier@0 SF
(__ Tunnels Compatible with Quick-Start)232.8 85 Q(/)226.2 98 Q
(Simple Tunnels)100.8 111 Q(__/)13.2 E(\\)219.6 124 Q
(\\__ Tunnels Not Compatible with Quick-Start)226.2 137 Q
(\(False Positives!\))318.6 150 Q(__ Tunnels Supporting Quick-Start)
259.2 189 Q(/)252.6 202 Q(/)246 215 Q
(Non-Simple Tunnels __/_____ Tunnels Compatible with Quick-Start,)100.8
228 Q 66(\\b)239.4 241 S(ut Not Supporting Quick-Start)-66 E(\\)246 254
Q(\\__ Tunnels Not Compatible with Quick-Start?)252.6 267 Q
(Figure 6: Categories of Tunnels.)100.8 293 Q F0 -.495(Tu)100.8 325 S
(nnels that are compatible with Quick-Start: W).495 E 2.75(es)-.88 G
(ay that an IP tunnel `is not compatible)-2.75 E
(with Quick-Start' if the use of a Quick-Start Request o)100.8 338 Q
-.165(ve)-.165 G 2.75(rs).165 G(uch a tunnel allo)-2.75 E(ws f)-.275 E
(alse)-.11 E(positi)100.8 351 Q -.165(ve)-.275 G
(s, where the TCP sender incorrectly belie).165 E -.165(ve)-.275 G 2.75
(st).165 G(hat the Quick-Start Request w)-2.75 E(as)-.11 E(appro)100.8
364 Q -.165(ve)-.165 G 2.75(db).165 G 2.75(ya)-2.75 G
(ll routers along the path.)-2.75 E(If the use of Quick-Start o)5.5 E
-.165(ve)-.165 G 2.75(rt).165 G(he tunnel does not)-2.75 E(cause f)100.8
377 Q(alse positi)-.11 E -.165(ve)-.275 G
(s, we say that the IP tunnel `is compatible with Quick-Start'.).165 E
(If the IP TTL of the inner header is decremented during forw)100.8 403
Q(arding before tunnel)-.11 E(encapsulation tak)100.8 416 Q
(es place, then the simple tunnel is compatible with Quick-Start, with)
-.11 E(Quick-Start requests being rejected.)100.8 429 Q
(Section 6.1 describes in more detail the w)5.5 E(ays that a)-.11 E
(simple tunnel can be compatible with Quick-Start.)100.8 442 Q(There ar\
e some simple tunnels that are not compatible with Quick-Start, allo)
100.8 468 Q(wing `f)-.275 E(alse)-.11 E(positi)100.8 481 Q -.165(ve)
-.275 G(s' where the TCP sender incorrectly belie).165 E -.165(ve)-.275
G 2.75(st).165 G(hat the Quick-Start Request w)-2.75 E(as)-.11 E(appro)
100.8 494 Q -.165(ve)-.165 G 2.75(db).165 G 2.75(ya)-2.75 G
(ll routers along the path.)-2.75 E
(This is discussed in Section 6.2 belo)5.5 E -.715(w.)-.275 G
(One of our tasks in the future will be to in)100.8 520 Q -.165(ve)-.44
G(stig).165 E(ate the occurrence of tunnels that are not)-.055 E
(compatible with Quick-Start, and to track the e)100.8 533 Q
(xtent to which such tunnels are modi\214ed)-.165 E -.165(ove)100.8 546
S 2.75(rt).165 G 2.75(ime. The)-2.75 F -.275(eva)2.75 G
(luation of the problem of f).275 E(alse positi)-.11 E -.165(ve)-.275 G
2.75(sf).165 G(rom tunnels that are not)-2.75 E
(compatible with Quick-Start will af)100.8 559 Q
(fect the progression of Quick-Start from Experimental)-.275 E
(to Proposed Standard, and will af)100.8 572 Q(fect the de)-.275 E
(gree of deplo)-.165 E(yment of Quick-Start while in)-.11 E
(Experimental mode.)100.8 585 Q -.495(Tu)100.8 611 S
(nnels that support Quick-Start: W).495 E 2.75(es)-.88 G
(ay that an IP tunnel `supports Quick-Start' if it)-2.75 E(allo)100.8
624 Q(ws routers along the tunnel path to process the Quick-Start Reque\
st and gi)-.275 E .33 -.165(ve f)-.275 H(eedback,).165 E(resulting in t\
he appropriate possible acceptance of the Quick-Start request.)100.8 637
Q(Some tunnels)5.5 E(that are compatible with Quick-Start support Quick\
-Start, while others do not.)100.8 650 Q 1.76 -.88(We n)5.5 H(ote).88 E
(that a simple tunnel is not able to support Quick-Start.)100.8 663 Q
(From a security point of vie)100.8 689 Q 1.43 -.715(w, t)-.275 H
(he use of Quick-Start in the outer header of an IP tunnel).715 E
(might raise security concerns because an adv)100.8 702 Q
(ersary could tamper with the Quick-Start)-.165 E
(information that propag)100.8 715 Q(ates be)-.055 E
(yond the tunnel endpoint, or because the Quick-Start Option)-.165 E
(Flo)72 769 Q 212.275(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(6. [P)2.75 F(age 33])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E -.165(ex)100.8 85 S
(poses information to netw).165 E(ork scanners.)-.11 E
(Our approach is to mak)5.5 E 2.75(es)-.11 G(upporting Quick-Start)-2.75
E(an option for IP tunnels.)100.8 98 Q(That is, in en)5.5 E
(vironments or tunneling protocols where the risks of)-.44 E(using Quic\
k-Start are judged to outweigh its bene\214ts, the tunnel can simply de\
lete the)100.8 111 Q(Quick-Start option or zero the Quick-Start rate re\
quest and QS TTL \214elds before)100.8 124 Q 2.75(encapsulation. The)
100.8 137 R(result is that there are tw)2.75 E 2.75(ov)-.11 G
(iable options for IP tunnels to be)-2.75 E
(compatible with Quick-Start.)100.8 150 Q
(The \214rst option is the simple tunnel described abo)5.5 E .33 -.165
(ve a)-.165 H(nd in).165 E
(Section 6.1, where the tunnel is compatible with Quick-Start b)100.8
163 Q(ut does not support Quick-)-.22 E
(Start, where all Quick-Start requests along the path will be rejected.)
100.8 176 Q(The second approach)5.5 E(is a Quick-Start-capable mode, de\
scribed in Section 6.3, where the tunnel acti)100.8 189 Q -.165(ve)-.275
G(ly supports).165 E(Quick-Start.)100.8 202 Q/F1 11/Times-Bold@0 SF
(6.1.)72 241 Q/F2 13/Times-Bold@0 SF(Simple T)5.5 E(unnels That Ar)
-1.196 E 3.25(eC)-.234 G(ompatible with Quick-Start)-3.25 E F0
(This section describes the w)100.8 267 Q
(ays that a simple tunnel can be compatible with Quick-Start)-.11 E -.22
(bu)100.8 280 S 2.75(tn).22 G(ot support Quick-Start, resulting in the \
rejection of all Quick-Start requests that)-2.75 E(tra)100.8 293 Q -.165
(ve)-.22 G(rse the tunnel.).165 E
(If the tunnel ingress for the simple tunnel is at a router)100.8 319 Q
2.75(,t)-.44 G(he IP TTL of the inner header is)-2.75 E
(generally decremented during forw)100.8 332 Q
(arding before tunnel encapsulation tak)-.11 E(es place.)-.11 E(In this)
5.5 E(case TTL Dif)100.8 345 Q 2.75(fw)-.275 G(ill be changed, correctl\
y causing the Quick-Start request to be rejected.)-2.75 E -.165(Fo)100.8
358 S 2.75(ras).165 G(imple tunnel it is preferable if the Quick-Start \
Request is not copied to the outer)-2.75 E(header)100.8 371 Q 2.75(,s)
-.44 G -.22(av)-2.75 G(ing the routers within the tunnel from unnecessa\
rily processing the Quick-Start).22 E 2.75(request. Ho)100.8 384 R(we)
-.275 E -.165(ve)-.275 G .88 -.44(r, t).165 H(he Quick-Start request wi\
ll be rejected correctly in this case whether or).44 E
(not the Quick-Start Request is copied to the outer header)100.8 397 Q
(.)-.605 E F1 2.75(6.1.1. Simple)72 436 R -1.012(Tu)2.75 G
(nnels that ar)1.012 E 2.75(eA)-.198 G(war)-3.74 E 2.75(eo)-.198 G 2.75
(fQ)-2.75 G(uick-Start)-2.75 E F0(If a tunnel ingress is a)100.8 462 Q
-.11(wa)-.165 G(re of Quick-Start, b).11 E(ut does not w)-.22 E
(ant to support Quick-Start, then)-.11 E(the tunnel ingress MUST either\
 zero the Quick-Start rate request, QS TTL, and QS Nonce)100.8 475 Q
(\214elds or remo)100.8 488 Q .33 -.165(ve t)-.165 H
(he Quick-Start option from the inner header before encapsulation.).165
E(Section 6.3 describes the procedures for a tunnel that does w)100.8
501 Q(ant to support Quick-Start.)-.11 E(Deleting the Quick-Start optio\
n or zeroing the Quick-Start rate request *after)100.8 527 Q
(decapsulation* also serv)100.8 540 Q(es to pre)-.165 E -.165(ve)-.275 G
(nt the propag).165 E(ation of Quick-Start information, and is)-.055 E
(compatible with Quick-Start.)100.8 553 Q
(If the outer header does not contain a Quick-Start Request, a)5.5 E
(Quick-Start-a)100.8 566 Q -.11(wa)-.165 G(re tunnel e).11 E
(gress MUST reject the inner Quick-Start Request by zeroing the)-.165 E
(Rate Request \214eld in the inner header)100.8 579 Q 2.75(,o)-.44 G
2.75(rb)-2.75 G 2.75(yd)-2.75 G(eleting the Quick-Start option.)-2.75 E
(If the tunnel ingress is at a sending host or router where the IP TTL \
is not decremented)100.8 605 Q
(prior to encapsulation, and neither tunnel endpoint is a)100.8 618 Q
-.11(wa)-.165 G(re of Quick-Start, then this allo).11 E(ws)-.275 E -.11
(fa)100.8 631 S(lse positi).11 E -.165(ve)-.275 G
(s, described in the section belo).165 E -.715(w.)-.275 G F1(6.2.)72 670
Q F2(Simple T)5.5 E(unnels That Ar)-1.196 E 3.25(eN)-.234 G
(ot Compatible with Quick-Start)-3.25 E F0(Sometimes a tunnel implement\
ation that does not support Quick-Start is independent of the)100.8 709
Q(TCP sender or a router implementation that supports Quick-Start.)100.8
722 Q(In these cases it is)5.5 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(6.2. [P)2.75 F(age 34])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E
(possible that a Quick-Start Request gets erroneously appro)100.8 85 Q
-.165(ve)-.165 G 2.75(dw).165 G(ithout the routers in the)-2.75 E
(tunnel ha)100.8 98 Q(ving indi)-.22 E(vidually appro)-.275 E -.165(ve)
-.165 G 2.75(dt).165 G(he request, causing a f)-2.75 E(alse positi)-.11
E -.165(ve)-.275 G(.).165 E(If a tunnel ingress is a separate component\
 from the TCP sender or IP forw)100.8 124 Q(arding, it is)-.11 E
(possible that a pack)100.8 137 Q
(et with a Quick-Start option is encapsulated without the IP TTL being)
-.11 E(decremented \214rst, or with both IP TTL and QS TTL being decrem\
ented before the tunnel)100.8 150 Q(encapsulation tak)100.8 163 Q
(es place. If the tunnel ingress does not kno)-.11 E 2.75(wa)-.275 G
(bout Quick-Start, a v)-2.75 E(alid)-.275 E
(Quick-Start Request with unchanged TTL Dif)100.8 176 Q 2.75(ft)-.275 G
(ra)-2.75 E -.165(ve)-.22 G(rses in the inner header).165 E 2.75(,w)-.44
G(hile the)-2.75 E(outer header most lik)100.8 189 Q
(ely does not carry a Quick-Start Request.)-.11 E(If the tunnel e)5.5 E
(gress also)-.165 E(does not support Quick-Start, it remains possible t\
hat the Quick-Start Request w)100.8 202 Q(ould be)-.11 E -.11(fa)100.8
215 S(lsely appro).11 E -.165(ve)-.165 G(d, because the pack).165 E
(et is decapsulated using the Quick-Start request from the)-.11 E
(inner header)100.8 228 Q 2.75(,a)-.44 G(nd the v)-2.75 E
(alue of TTL Dif)-.275 E 2.75(fe)-.275 G
(choed to the sender remains unchanged.)-2.75 E -.165(Fo)5.5 G(r).165 E
-.165(ex)100.8 241 S(ample, such a scenario can occur with a Bump-In-Th\
e-Stack \(BITS\), an IPSec).165 E(encryption implementation where the d\
ata encryption occurs between the netw)100.8 254 Q(ork dri)-.11 E -.165
(ve)-.275 G(rs).165 E(and the TCP/IP protocol stack [RFC4301].)100.8 267
Q(As one e)100.8 293 Q(xample, if a remote access VPN client uses a BIT\
S structure, then Quick-Start)-.165 E
(obstacles between the client and the VPN g)100.8 306 Q(ate)-.055 E -.11
(wa)-.275 G 2.75(yw).11 G(on')-2.86 E 2.75(tb)-.198 G 2.75(es)-2.75 G
5.5(een. This)-2.75 F(is a particular)2.75 E
(problem because the path between the client and the VPN g)100.8 319 Q
(ate)-.055 E -.11(wa)-.275 G 2.75(yi).11 G 2.75(sl)-2.75 G(ik)-2.75 E
(ely to contain the)-.11 E(most congested part of the path.)100.8 332 Q
(Because most VPN clients are reported to use BITS)5.5 E
([H05], we will e)100.8 345 Q(xplore this in more detail.)-.165 E 2.75
(AB)100.8 371 S(ump-In-The-W)-2.75 E
(ire \(BITW\) is an IPSec encryption implementation where the)-.44 E
(encryption occurs on an outboard processor)100.8 384 Q 2.75(,o)-.44 G
-.275<668d>-2.75 G(oading the encryption processing o).275 E -.165(ve)
-.165 G(rhead).165 E(from the host or router [RFC4301].)100.8 397 Q
(The BITW de)5.5 E(vice is usually IP addressable, which)-.275 E
(means that the IP TTL is decremented before the pack)100.8 410 Q
(et is passed to the BITW)-.11 E 5.5(.I)-1.012 G 2.75(ft)-5.5 G(he QS)
-2.75 E(TTL is not decremented, then the v)100.8 423 Q(alue of TTL Dif)
-.275 E 2.75(fi)-.275 G 2.75(sc)-2.75 G(hanged, and the Quick-Start)
-2.75 E(request will be denied.)100.8 436 Q(Ho)5.5 E(we)-.275 E -.165
(ve)-.275 G .88 -.44(r, i).165 H 2.75(ft).44 G
(he BITW supports a host and does not ha)-2.75 E .33 -.165(ve i)-.22 H
(ts o).165 E(wn IP)-.275 E
(address, then the IP TTL is not decremented before the pack)100.8 449 Q
(et is passed from the host to)-.11 E(the BITW)100.8 462 Q 2.75(,a)
-1.012 G(nd a f)-2.75 E(alse positi)-.11 E .33 -.165(ve c)-.275 H
(ould occur).165 E(.)-.605 E(Other tunnels that need to be look)100.8
488 Q(ed at are IP tunnels o)-.11 E -.165(ve)-.165 G 2.75(rn).165 G
(on-netw)-2.75 E(ork protocols, such as)-.11 E(IP o)100.8 501 Q -.165
(ve)-.165 G 2.75(rT).165 G(CP and IP o)-2.75 E -.165(ve)-.165 G 2.75(rU)
.165 G(DP [RFC3948], and tunnels using the Layer T)-2.75 E .22 -.11
(wo T)-.88 H(unneling)-.385 E(Protocol [RFC2661].)100.8 514 Q(Section 9\
.2 discusses the related issue of non-IP queues, such as layer)100.8 540
Q(-tw)-.22 E 2.75(oE)-.11 G(thernet or)-2.75 E -1.221(AT)100.8 553 S
2.75(Mn)1.221 G(etw)-2.75 E(orks, as another instance of possible bottl\
enecks that do not participate in the)-.11 E(Quick-Start feedback.)100.8
566 Q/F1 11/Times-Bold@0 SF(6.3.)72 605 Q/F2 13/Times-Bold@0 SF -1.196
(Tu)5.5 G(nnels That Support Quick-Start)1.196 E F0
(This section discusses tunnels con\214gured to support Quick-Start.)
100.8 631 Q(If the tunnel ingress node chooses to locally appro)100.8
657 Q .33 -.165(ve t)-.165 H(he Quick-Start request, then the).165 E(in\
gress node MUST decrement the Quick-Start TTL at the same time it decre\
ments the IP)100.8 670 Q(TTL, and MUST cop)100.8 683 Q 2.75(yI)-.11 G
2.75(PT)-2.75 G
(TL and the Quick-Start option from the inner IP header to the)-2.75 E
(outer header)100.8 696 Q 5.5(.D)-.605 G
(uring encapsulation, the tunnel ingress MUST zero the Quick-Start rate)
-5.5 E(request \214eld in the inner header to ensure that the Quick-Sta\
rt request will be rejected if the)100.8 709 Q(tunnel e)100.8 722 Q
(gress does not support Quick-Start.)-.165 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(6.3. [P)2.75 F(age 35])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
(If the tunnel ingress node does not choose to locally appro)100.8 85 Q
.33 -.165(ve t)-.165 H(he Quick-Start request, then).165 E(it MUST eith\
er delete the Quick-Start option from the inner header before encapsula\
tion,)100.8 98 Q
(or zero the QS TTL and the Rate Request \214elds before encapsulation.)
100.8 111 Q(Upon decapsulation, if the outer header contains a Quick-St\
art option, the tunnel e)100.8 137 Q(gress)-.165 E(MUST cop)100.8 150 Q
2.75(yt)-.11 G(he IP TTL and the Quick-Start option from the outer IP h\
eader to the inner)-2.75 E(header)100.8 163 Q(.)-.605 E
(IPsec uses the IKE \(Internet K)100.8 189 Q .33 -.165(ey E)-.275 H
(xchange\) Protocol for security associations.).165 E 1.76 -.88(We d)5.5
H 2.75(on).88 G(ot)-2.75 E(consider the interactions between Quick-Star\
t and IPsec with IKEv1 [RFC2409] in this)100.8 202 Q 2.75(document. No)
100.8 215 R 2.75(wt)-.275 G
(hat the RFC for IKEv2 [RFC4306] is published, we plan to specify a)
-2.75 E(modi\214cation of IPsec to allo)100.8 228 Q 2.75(wt)-.275 G
(he support of Quick-Start to be ne)-2.75 E
(gotiated; this modi\214cation)-.165 E(will specify the ne)100.8 241 Q
(gotiation between tunnel endpoints to allo)-.165 E 2.75(wo)-.275 G 2.75
(rf)-2.75 G(orbid support for Quick-)-2.75 E(Start within the tunnel.)
100.8 254 Q(This w)5.5 E
(as done for ECN for IPsec tunnels, with IKEv1 [RFC3168,)-.11 E
(Section 9.2].)100.8 267 Q(This ne)5.5 E(gotiation of Quick-Start capab\
ility in an IPsec tunnel will be speci\214ed)-.165 E
(in a separate IPsec document.)100.8 280 Q
(This document will also include a discussion of the potential)5.5 E(ef)
100.8 293 Q(fects of an adv)-.275 E(ersary')-.165 E 2.75(sm)-.605 G(odi\
\214cations of the Quick-Start \214eld \(as in Sections 18 and 19 of)
-2.75 E(RFC 3168\), and of the security considerations of e)100.8 306 Q
(xposing the Quick-Start rate request to)-.165 E(netw)100.8 319 Q
(ork scanners.)-.11 E/F1 11/Times-Bold@0 SF(6.4.)72 371 Q/F2 13
/Times-Bold@0 SF(Quick-Start and MPLS)5.5 E F0(The beha)100.8 397 Q
(vior of Quick-Start with MPLS is similar to the beha)-.22 E
(vior of Quick-Start with IP)-.22 E -.495(Tu)100.8 410 S 2.75(nnels. F)
.495 F
(or those MPLS paths where the IP TTL is decremented as part of tra)
-.165 E -.165(ve)-.22 G(rsing the).165 E
(MPLS path, these paths are compatible with Quick-Start, b)100.8 423 Q
(ut do not support Quick-Start;)-.22 E(Quick-Start requests tra)100.8
436 Q -.165(ve)-.22 G
(rsing these paths will be correctly understood by the transport).165 E
(sender as ha)100.8 449 Q(ving been denied.)-.22 E(An)5.5 E 2.75(yM)
-.165 G(PLS paths where the IP TTL is not decremented as)-2.75 E
(part of tra)100.8 462 Q -.165(ve)-.22 G(rsing the MPLS path w).165 E
(ould be not compatible with Quick-Start; such paths)-.11 E -.11(wo)
100.8 475 S(uld result in f).11 E(alse positi)-.11 E -.165(ve)-.275 G
(s, where the TCP sender incorrectly belie).165 E -.165(ve)-.275 G 2.75
(st).165 G(hat the Quick-)-2.75 E(Start Request w)100.8 488 Q(as appro)
-.11 E -.165(ve)-.165 G 2.75(db).165 G 2.75(ya)-2.75 G
(ll routers along the path.)-2.75 E -.165(Fo)100.8 514 S 2.75(rc).165 G
(ases where the ingress node to the MPLS path is a)-2.75 E -.11(wa)-.165
G(re of Quick-Start, this node).11 E(should either zero the Quick-Start\
 rate request, QS TTL, and QS Nonce \214elds or remo)100.8 527 Q -.165
(ve)-.165 G(the Quick-Start option from the IP header)100.8 540 Q(.)
-.605 E F1(7.)72 579 Q/F3 14/Times-Bold@0 SF
(The Quick-Start Mechanism in other T)5.5 E(ransport Pr)-1.036 E
(otocols)-.252 E F0
(The section earlier speci\214ed the use of Quick-Start in TCP)100.8 605
Q 5.5(.I)-1.221 G 2.75(nt)-5.5 G(his section, we generalize)-2.75 E
(this to gi)100.8 618 Q .33 -.165(ve g)-.275 H
(uidelines for the use of Quick-Start with other transport protocols.)
.165 E 1.76 -.88(We a)5.5 H(lso).88 E(discuss brie\215y ho)100.8 631 Q
2.75(wQ)-.275 G
(uick-Start could be speci\214ed for other transport protocols.)-2.75 E
(The general guidelines for Quick-Start in transport protocols are as f\
ollo)100.8 657 Q(ws:)-.275 E 2.75(*Q)100.8 683 S(uick-Start is only spe\
ci\214ed for unicast transport protocols with appropriate congestion)
-2.75 E(control mechanisms.)100.8 696 Q
(Note: Quick-Start is not a replacement for standard congestion)5.5 E
(control techniques, b)100.8 709 Q(ut meant to augment their operation.)
-.22 E(Flo)72 769 Q 212.275(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(7. [P)2.75 F(age 36])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E 2.75(*At)100.8 85 S
(ransport-le)-2.75 E -.165(ve)-.275 G 2.75(lm).165 G
(echanism is needed for the Quick-Start response from the recei)-2.75 E
-.165(ve)-.275 G 2.75(rt).165 G(o)-2.75 E(the sender)100.8 98 Q 5.5(.T)
-.605 G(his response contains the Rate Request, TTL Dif)-5.5 E
(f, and QS Nonce.)-.275 E 2.75(*T)100.8 124 S(he sender checks the v)
-2.75 E(alidity of the Quick-Start response.)-.275 E 2.75(*T)100.8 150 S
(he sender has an estimate of the round-trip time, and translates the Q\
uick-Start response)-2.75 E(into an allo)100.8 163 Q(wed windo)-.275 E
2.75(wo)-.275 G 2.75(ra)-2.75 G(llo)-2.75 E(wed sending rate.)-.275 E
(The sender sends a Report of the)5.5 E(Appro)100.8 176 Q -.165(ve)-.165
G 2.75(dR).165 G 2.75(ate. The)-2.75 F
(sender starts sending Quick-Start pack)2.75 E
(ets, rate-paced out at the)-.11 E(appro)100.8 189 Q -.165(ve)-.165 G
2.75(ds).165 G(ending rate.)-2.75 E 2.75(*A)100.8 215 S
(fter the sender recei)-2.75 E -.165(ve)-.275 G 2.75(st).165 G
(he \214rst ackno)-2.75 E(wledgement pack)-.275 E
(et for a Quick-Start pack)-.11 E(et, no)-.11 E(more Quick-Start pack)
100.8 228 Q(ets are sent.)-.11 E
(The sender adjusts its current congestion windo)5.5 E 2.75(wo)-.275 G
(r)-2.75 E
(sending rate to be consistent with the actual amount of data that w)
100.8 241 Q(as transmitted in that)-.11 E(round-trip time.)100.8 254 Q
2.75(*W)100.8 280 S(hen the last Quick-Start pack)-2.75 E(et is ackno)
-.11 E(wledged, the sender continues using the)-.275 E
(standard congestion control mechanisms of that protocol.)100.8 293 Q
2.75(*I)100.8 319 S 2.75(fo)-2.75 G(ne of the Quick-Start pack)-2.75 E
(ets is lost, then the sender re)-.11 E -.165(ve)-.275 G
(rts to the standard congestion).165 E
(control method of that protocol that w)100.8 332 Q(ould ha)-.11 E .33
-.165(ve b)-.22 H(een used if the Quick-Start request had).165 E
(not been appro)100.8 345 Q -.165(ve)-.165 G 2.75(d. In).165 F
(addition, the sender tak)2.75 E
(es into account the information that the)-.11 E
(Quick-Start congestion windo)100.8 358 Q 2.75(ww)-.275 G(as too lar)
-2.86 E(ge \(e.g., by decreasing ssthresh in TCP\).)-.198 E/F1 11
/Times-Bold@0 SF(8.)72 397 Q/F2 14/Times-Bold@0 SF(Using Quick-Start)5.5
E F1(8.1.)72 436 Q/F3 13/Times-Bold@0 SF
(Determining the Rate to Request)5.5 E F0
(As discussed in [SAF06], the data sender does not necessarily ha)100.8
462 Q .33 -.165(ve i)-.22 H(nformation about the).165 E
(size of the data transfer at connection initiation; for e)100.8 475 Q
(xample, in request-response protocols)-.165 E(such as HTTP)100.8 488 Q
2.75(,t)-1.221 G(he serv)-2.75 E(er doesn')-.165 E 2.75(tk)-.198 G(no)
-2.75 E 2.75(wt)-.275 G(he size or name of the requested object during)
-2.75 E(connection initiation.)100.8 501 Q([SAF06] e)5.5 E
(xplores some of the performance implications of o)-.165 E -.165(ve)
-.165 G(rly-).165 E(lar)100.8 514 Q(ge Quick-Start requests, and discus\
ses heuristics that end-nodes could use to size their)-.198 E
(requests appropriately)100.8 527 Q 5.5(.F)-.715 G(or e)-5.665 E
(xample, the sender might ha)-.165 E .33 -.165(ve i)-.22 H
(nformation about the).165 E
(bandwidth of the last-mile hop, the size of the local sock)100.8 540 Q
(et b)-.11 E(uf)-.22 E(fer)-.275 E 2.75(,o)-.44 G 2.75(ro)-2.75 G 2.75
(ft)-2.75 G(he TCP recei)-2.75 E -.165(ve)-.275 G(windo)100.8 553 Q 1.43
-.715(w, a)-.275 H
(nd could use this information in determining the rate to request.).715
E -.88(We)5.5 G 2.75(bs).88 G(erv)-2.75 E(ers)-.165 E(that mostly ha)
100.8 566 Q .33 -.165(ve s)-.22 H(mall objects to transfer might decide\
 not to use Quick-Start at all, since).165 E(Quick-Start w)100.8 579 Q
(ould be of little bene\214t to them.)-.11 E
(Quick-Start will be more ef)100.8 605 Q(fecti)-.275 E .33 -.165(ve i)
-.275 H 2.75(fQ).165 G(uick-Start requests are not lar)-2.75 E
(ger than necessary;)-.198 E -2.365 -.275(ev e)100.8 618 T
(ry Quick-Start request that is appro).275 E -.165(ve)-.165 G 2.75(db)
.165 G(ut not used \(or not fully used\) tak)-2.97 E(es a)-.11 E -.11
(wa)-.165 G 2.75(yf).11 G(rom)-2.75 E(the bandwidth pool a)100.8 631 Q
-.275(va)-.22 G(ilable for granting successi).275 E .33 -.165(ve Q)-.275
H(uick-Start requests.).165 E F1(8.2.)72 670 Q F3(Deciding the P)5.5 E
(ermitted Rate Request at a Router)-.26 E F0
(In this section we brie\215y outline ho)100.8 696 Q 2.75(war)-.275 G
(outer might decide whether or not to appro)-2.75 E .33 -.165(ve a)-.165
H(Quick-Start Request.)100.8 709 Q(The router should ask the follo)5.5 E
(wing questions:)-.275 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(8.2. [P)2.75 F(age 37])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E 2.75(*H)100.8 85 S
(as the router')-2.75 E 2.75(so)-.605 G
(utput link been underutilized for some time \(e.g., se)-2.75 E -.165
(ve)-.275 G(ral seconds\).).165 E 2.75(*W)100.8 111 S
(ould the output link remain underutilized if the arri)-3.63 E -.275(va)
-.275 G 2.75(lr).275 G(ate w)-2.75 E(as to increase by the)-.11 E(aggre)
100.8 124 Q -.055(ga)-.165 G(te rate requests that the router has appro)
.055 E -.165(ve)-.165 G 2.75(do).165 G -.165(ve)-2.915 G 2.75(rt).165 G
(he last fraction of a second?)-2.75 E
(In order to answer the last question, the router must ha)100.8 150 Q
.33 -.165(ve s)-.22 H(ome kno).165 E(wledge of the a)-.275 E -.275(va)
-.22 G(ilable).275 E(bandwidth on the output link and of the Quick-Star\
t bandwidth that could arri)100.8 163 Q .33 -.165(ve d)-.275 H(ue to)
.165 E(recently-appro)100.8 176 Q -.165(ve)-.165 G 2.75(dQ).165 G
(uick-Start Requests.)-2.75 E(In this w)5.5 E(ay)-.11 E 2.75(,i)-.715 G
2.75(fa)-2.75 G 2.75(nu)-2.75 G(nderutilized router e)-2.75 E
(xperiences)-.165 E 2.75<618d>100.8 189 S
(ood of Quick-Start requests, the router can be)-2.75 E(gin to den)-.165
E 2.75(yQ)-.165 G(uick-Start requests while the)-2.75 E
(output link is still underutilized.)100.8 202 Q 2.75(As)100.8 228 S
(imple w)-2.75 E(ay for the router to k)-.11 E
(eep track of the potential bandwidth from recently-)-.11 E(appro)100.8
241 Q -.165(ve)-.165 G 2.75(dr).165 G(equests is to maintain tw)-2.75 E
2.75(oc)-.11 G(ounters, one for the total aggre)-2.75 E -.055(ga)-.165 G
(te Rate Requests).055 E(that ha)100.8 254 Q .33 -.165(ve b)-.22 H
(een appro).165 E -.165(ve)-.165 G 2.75(di).165 G 2.75(nt)-2.75 G
(he current time interv)-2.75 E(al [T1, T2], and one for the total)-.275
E(aggre)100.8 267 Q -.055(ga)-.165 G(te Rate Requests appro).055 E -.165
(ve)-.165 G 2.75(do).165 G -.165(ve)-2.915 G 2.75(rap).165 G(re)-2.75 E
(vious time interv)-.275 E(al [T0, T1].)-.275 E(Ho)5.5 E(we)-.275 E
-.165(ve)-.275 G .88 -.44(r, t).165 H(his).44 E(document doesn')100.8
280 Q 2.75(ts)-.198 G(pecify router algorithms for appro)-2.75 E
(ving Quick-Start requests, or mak)-.165 E(e)-.11 E
(requirements for the appropriate time interv)100.8 293 Q
(als for remembering the aggre)-.275 E -.055(ga)-.165 G(te appro).055 E
-.165(ve)-.165 G(d).165 E(Quick-Start bandwidth.)100.8 306 Q 2.75(Ap)5.5
G(ossible router algorithm is gi)-2.75 E -.165(ve)-.275 G 2.75(ni).165 G
2.75(nA)-2.75 G(ppendix E, and more)-2.75 E
(discussion of these issues is a)100.8 319 Q -.275(va)-.22 G
(ilable in [SAF06].\)).275 E 2.75(*I)100.8 345 S 2.75(ft)-2.75 G
(he router')-2.75 E 2.75(so)-.605 G
(utput link has been underutilized and the aggre)-2.75 E -.055(ga)-.165
G(te of the Quick-Start).055 E(Request Rate options granted is lo)100.8
358 Q 2.75(we)-.275 G(nough to pre)-2.75 E -.165(ve)-.275 G(nt a near)
.165 E(-term bandwidth shortage,)-.22 E(then the router could appro)
100.8 371 Q .33 -.165(ve t)-.165 H(he Quick-Start Request.).165 E(Secti\
on 10.2 discusses some of the implementation issues in processing Quick\
-Start)100.8 397 Q(requests at routers.)100.8 410 Q
([SAF06] discusses the range of possible Quick-Start algorithms at the)
5.5 E(router for deciding whether to appro)100.8 423 Q .33 -.165(ve a Q)
-.165 H(uick-Start request.).165 E(In order to e)5.5 E
(xplore the limits)-.165 E(of the possible functionality at routers, [S\
AF06] also discusses Extreme Quick-Start)100.8 436 Q
(mechanisms at routers, where the router w)100.8 449 Q(ould k)-.11 E
(eep per)-.11 E(-\215o)-.22 E 2.75(ws)-.275 G(tate concerning appro)
-2.75 E -.165(ve)-.165 G(d).165 E(Quick-Start requests.)100.8 462 Q/F1
11/Times-Bold@0 SF(9.)72 501 Q/F2 14/Times-Bold@0 SF(Ev)5.5 E
(aluation of Quick-Start)-.14 E F1(9.1.)72 540 Q/F3 13/Times-Bold@0 SF
(Bene\214ts of Quick-Start)5.5 E F0
(The main bene\214t of Quick-Start is the f)100.8 566 Q
(aster start-up for the transport connection itself.)-.11 E -.165(Fo)5.5
G(r).165 E 2.75(as)100.8 579 S(mall TCP transfer of one to \214v)-2.75 E
2.75(ep)-.165 G(ack)-2.75 E(ets, Quick-Start is probably of v)-.11 E
(ery little bene\214t;)-.165 E(at)5.5 E
(best, it might shorten the connection lifetime from three to tw)100.8
592 Q 2.75(or)-.11 G(ound-trip times \(including)-2.75 E
(the round-trip time for connection establishment\).)100.8 605 Q
(Similarly)5.5 E 2.75(,f)-.715 G(or a v)-2.75 E(ery lar)-.165 E
(ge transfer)-.198 E(,)-.44 E(where the slo)100.8 618 Q(w-start phase w)
-.275 E(ould ha)-.11 E .33 -.165(ve b)-.22 H
(een only a small fraction of the connection).165 E
(lifetime, Quick-Start w)100.8 631 Q(ould be of limited bene\214t.)-.11
E(Quick-Start w)5.5 E(ould not signi\214cantly)-.11 E
(shorten the connection lifetime, b)100.8 644 Q
(ut it might eliminate or at least shorten the start-up phase.)-.22 E
(Ho)100.8 657 Q(we)-.275 E -.165(ve)-.275 G .88 -.44(r, f).165 H
(or moderate-sized connections in a well-pro).44 E(visioned en)-.165 E
(vironment, Quick-Start)-.44 E(could possibly allo)100.8 670 Q 2.75(wt)
-.275 G(he entire transfer of M pack)-2.75 E
(ets to be completed in one round-trip)-.11 E
(time \(after the initial round-trip time for the SYN e)100.8 683 Q
(xchange\), instead of the log_2\(M\)-2)-.165 E
(round-trip times that it w)100.8 696 Q(ould normally tak)-.11 E 2.75
(ef)-.11 G(or the data transfer)-2.75 E 2.75(,i)-.44 G 2.75(na)-2.75 G
2.75(nu)-2.75 G(ncongested)-2.75 E(en)100.8 709 Q
(vironments \(assuming an initial windo)-.44 E 2.75(wo)-.275 G 2.75(ff)
-2.75 G(our pack)-2.75 E(ets\).)-.11 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.1. [P)2.75 F(age 38])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E/F1 11/Times-Bold@0 SF(9.2.)72
85 Q/F2 13/Times-Bold@0 SF(Costs of Quick-Start)5.5 E F0(This section d\
iscusses the costs of Quick-Start for the connection and for the router\
s along)100.8 111 Q(the path.)100.8 124 Q(The cost of ha)100.8 150 Q
(ving a Quick-Start pack)-.22 E(et dropped:)-.11 E -.165(Fo)100.8 163 S
2.75(rt).165 G(he sender the biggest risk in using Quick-Start lies in \
the possibility of suf)-2.75 E(fering from)-.275 E
(congestion-related losses of the Quick-Start pack)100.8 176 Q 2.75
(ets. This)-.11 F(should be an unlik)2.75 E(ely situation)-.11 E
(because routers are e)100.8 189 Q(xpected to appro)-.165 E .33 -.165
(ve Q)-.165 H(uick-Start Requests only when the).165 E 2.75(ya)-.165 G
(re)-2.75 E(signi\214cantly underutilized. Ho)100.8 202 Q(we)-.275 E
-.165(ve)-.275 G .88 -.44(r, a t).165 H(ransient increase in cross-traf)
.44 E(\214c in one of the)-.275 E(routers, a sudden decrease in a)100.8
215 Q -.275(va)-.22 G
(ilable bandwidth on one of the links, or congestion at a).275 E
(non-IP queue could result in pack)100.8 228 Q(et losses e)-.11 E -.165
(ve)-.275 G 2.75(nw).165 G(hen the Quick-Start Request w)-2.75 E(as)-.11
E(appro)100.8 241 Q -.165(ve)-.165 G 2.75(db).165 G 2.75(ya)-2.75 G
(ll of the routers along the path.)-2.75 E(If a Quick-Start pack)5.5 E
(et is dropped, then the)-.11 E(sender re)100.8 254 Q -.165(ve)-.275 G
(rts to the congestion control mechanisms it w).165 E(ould ha)-.11 E .33
-.165(ve u)-.22 H(sed if the Quick-Start).165 E
(request had not been appro)100.8 267 Q -.165(ve)-.165 G
(d, so the performance cost to the connection of ha).165 E(ving a)-.22 E
(Quick-Start pack)100.8 280 Q
(et dropped is small, compared to the performance without Quick-Start.)
-.11 E(\(On the other hand, the performance dif)100.8 293 Q
(ference between Quick-Start with a Quick-Start)-.275 E(pack)100.8 306 Q
(et dropped and Quick-Start with no Quick-Start pack)-.11 E
(et dropped can be considerable.\))-.11 E(Added comple)100.8 332 Q
(xity at routers:)-.165 E(The main cost of Quick-Start at routers conce\
rns the costs of added comple)100.8 345 Q(xity)-.165 E 5.5(.T)-.715 G
(he added)-5.5 E(comple)100.8 358 Q(xity at the end-points is moderate,\
 and might easily be outweighed by the bene\214t of)-.165 E
(Quick-Start to the end hosts.)100.8 371 Q(The added comple)5.5 E
(xity at the routers is also some)-.165 E(what)-.275 E(moderate; it in)
100.8 384 Q -.22(vo)-.44 G(lv).22 E
(es estimating the unused bandwidth on the output link o)-.165 E -.165
(ve)-.165 G 2.75(rt).165 G(he last)-2.75 E(se)100.8 397 Q -.165(ve)-.275
G(ral seconds, processing the Quick-Start request, and k).165 E
(eeping a counter of the aggre)-.11 E -.055(ga)-.165 G(te).055 E
(Quick-Start rate appro)100.8 410 Q -.165(ve)-.165 G 2.75(do).165 G
-.165(ve)-2.915 G 2.75(rt).165 G(he last fraction of a second.)-2.75 E
(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44(r, t).165 H(his added).44
E(comple)100.8 423 Q(xity at routers adds to the de)-.165 E -.165(ve)
-.275 G(lopment c).165 E(ycle, and could pre)-.165 E -.165(ve)-.275 G
(nt the addition of).165 E(other competing functionality to routers.)
100.8 436 Q(Thus, careful thought w)5.5 E(ould ha)-.11 E .33 -.165(ve t)
-.22 H 2.75(ob).165 G 2.75(eg)-2.75 G -2.365 -.275(iv e)-2.75 H 2.75(nt)
.275 G(o)-2.75 E(the addition of Quick-Start to IP)100.8 449 Q(.)-1.221
E(The slo)100.8 475 Q 2.75(wp)-.275 G(ath in routers:)-2.75 E
(Another dra)100.8 488 Q(wback of Quick-Start is that pack)-.165 E
(ets containing the Quick-Start Request)-.11 E(message might not tak)
100.8 501 Q 2.75(et)-.11 G(he f)-2.75 E
(ast path in routers, particularly in the be)-.11 E(ginning of Quick-)
-.165 E(Start')100.8 514 Q 2.75(sd)-.605 G(eplo)-2.75 E
(yment in the Internet.)-.11 E(This w)5.5 E(ould mean some e)-.11 E
(xtra delay for the end hosts,)-.165 E(and e)100.8 527 Q
(xtra processing b)-.165 E(urden for the routers.)-.22 E(Ho)5.5 E(we)
-.275 E -.165(ve)-.275 G .88 -.44(r, a).165 H 2.75(sd).44 G
(iscussed in Sections 4.1 and 4.7,)-2.75 E(not all pack)100.8 540 Q
(ets w)-.11 E(ould carry the Quick-Start option.)-.11 E
(In addition, for the underutilized links)5.5 E
(where Quick-Start Requests could actually be appro)100.8 553 Q -.165
(ve)-.165 G(d, or in typical en).165 E(vironments where)-.44 E
(most of the pack)100.8 566 Q(ets belong to lar)-.11 E(ge \215o)-.198 E
(ws, the b)-.275 E(urden of the Quick-Start Option on routers)-.22 E
-.11(wo)100.8 579 S(uld be considerably reduced.).11 E(Ne)5.5 E -.165
(ve)-.275 G(rtheless, it is still concei).165 E -.275(va)-.275 G
(ble, in the w).275 E(orst case, that)-.11 E(man)100.8 592 Q 2.75(yp)
-.165 G(ack)-2.75 E(ets w)-.11 E
(ould carry Quick-Start requests; this could slo)-.11 E 2.75(wd)-.275 G
-.275(ow)-2.75 G 2.75(nt).275 G(he processing of)-2.75 E
(Quick-Start pack)100.8 605 Q(ets in routers considerably)-.11 E 5.5(.A)
-.715 G 2.75(sd)-5.5 G(iscussed in Section 9.6, routers can easily)-2.75
E(protect ag)100.8 618 Q(ainst this by enforcing a limit on the rate at\
 which Quick-Start requests will be)-.055 E 2.75(considered. [R)100.8
631 R(W03] and [R)-.605 E
(W04] contain measurements of the impact of IP Option)-.605 E
(Processing on pack)100.8 644 Q(et round-trip times.)-.11 E
(Multiple paths:)100.8 670 Q
(One limitation of Quick-Start is that it presumes that the data pack)
100.8 683 Q(ets of a connection will)-.11 E(follo)100.8 696 Q 2.75(wt)
-.275 G(he same path as the Quick-Start request pack)-2.75 E 2.75
(et. If)-.11 F(this is not the case, then the)2.75 E
(connection could be sending the Quick-Start pack)100.8 709 Q
(ets, at the appro)-.11 E -.165(ve)-.165 G 2.75(dr).165 G
(ate, along a path that)-2.75 E -.11(wa)100.8 722 S 2.75(sa).11 G(lread\
y congested, or that became congested as a result of this connection.)
-2.75 E(Thus,)5.5 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.2. [P)2.75 F(age 39])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(Quick-Start could gi)100.8 85
Q .33 -.165(ve p)-.275 H
(oor performance when there is a routing change immediately after).165 E
(the Quick-Start request is appro)100.8 98 Q -.165(ve)-.165 G
(d, and the Quick-Start data pack).165 E(ets follo)-.11 E 2.75(wad)-.275
G(if)-2.75 E(ferent)-.275 E
(path from that of the original Quick-Start Request.)100.8 111 Q
(This is, ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44(r, s).165 H
(imilar to what w).44 E(ould)-.11 E(happen, for a connection with suf)
100.8 124 Q(\214cient data, if the connection')-.275 E 2.75(sp)-.605 G
(ath w)-2.75 E(as changed in the)-.11 E(middle of the connection, when \
the connection had already established the allo)100.8 137 Q(wed initial)
-.275 E(rate.)100.8 150 Q(As speci\214ed in Section 3.3, a router that \
uses multipath routing for pack)100.8 176 Q(ets within a single)-.11 E
(connection must not appro)100.8 189 Q .33 -.165(ve a Q)-.165 H
(uick-Start request.).165 E(Quick-Start w)5.5 E(ould not perform)-.11 E
(rob)100.8 202 Q(ustly in an en)-.22 E
(vironment with multipath routing, where dif)-.44 E(ferent pack)-.275 E
(ets in a connection)-.11 E(routinely follo)100.8 215 Q 2.75(wd)-.275 G
(if)-2.75 E(ferent paths.)-.275 E(In such an en)5.5 E
(vironment, the Quick-Start request and some)-.44 E
(fraction of the pack)100.8 228 Q(ets in the connection might tak)-.11 E
2.75(ea)-.11 G 2.75(nu)-2.75 G(nderutilized path, while the rest of)
-2.75 E(the pack)100.8 241 Q(ets tak)-.11 E 2.75(ea)-.11 G 2.75(na)-2.75
G(lternate, congested path.)-2.75 E(Non-IP queues:)100.8 267 Q 2.75(Ap)
100.8 280 S(roblem of an)-2.75 E 2.75(ym)-.165 G
(echanism for feedback from routers at the IP le)-2.75 E -.165(ve)-.275
G 2.75(li).165 G 2.75(st)-2.75 G(hat there can be)-2.75 E
(queues and bottlenecks in the end-to-end path that are not in IP-le)
100.8 293 Q -.165(ve)-.275 G 2.75(lr).165 G 2.75(outers. As)-2.75 F(an)
2.75 E -.165(ex)100.8 306 S(ample, these include queues in layer).165 E
(-tw)-.22 E 2.75(oE)-.11 G(thernet or A)-2.75 E(TM netw)-1.221 E 2.75
(orks. One)-.11 F(possibility)2.75 E -.11(wo)100.8 319 S
(uld be that an IP-le).11 E -.165(ve)-.275 G 2.75(lr).165 G
(outer adjacent to such a non-IP queue or bottleneck w)-2.75 E(ould be)
-.11 E(con\214gured to reject Quick-Start requests if that w)100.8 332 Q
(as appropriate.)-.11 E(One w)5.5 E(ould hope that in)-.11 E
(general, IP netw)100.8 345 Q(orks are con\214gured so that non-IP queu\
es between IP routers do not end up)-.11 E
(being the congested bottlenecks.)100.8 358 Q/F1 11/Times-Bold@0 SF
(9.3.)72 397 Q/F2 13/Times-Bold@0 SF(Quick-Start with QoS-enabled T)5.5
E(raf\214c)-.962 E F0(The discussion in this document has lar)100.8 423
Q(gely been of Quick-Start with def)-.198 E(ault, best-ef)-.11 E(fort)
-.275 E(traf)100.8 436 Q 2.75(\214c. Ho)-.275 F(we)-.275 E -.165(ve)
-.275 G .88 -.44(r, Q).165 H(uick-Start could also be used by traf).44 E
(\214c using some form of)-.275 E(dif)100.8 449 Q
(ferentiated services, and routers could tak)-.275 E 2.75(et)-.11 G
(he traf)-2.75 E(\214c class into account when deciding)-.275 E
(whether or not to grant the Quick-Start request.)100.8 462 Q 1.76 -.88
(We d)5.5 H(on').88 E 2.75(ta)-.198 G(ddress this conte)-2.75 E
(xt further in)-.165 E(this paper)100.8 475 Q 2.75(,s)-.44 G
(ince it is orthogonal to the speci\214cation of Quick-Start.)-2.75 E
(Routers are also free to tak)100.8 501 Q 2.75(ei)-.11 G
(nto account their o)-2.75 E
(wn priority classi\214cations in processing)-.275 E
(Quick-Start requests.)100.8 514 Q F1(9.4.)72 553 Q F2(Pr)5.5 E
(otection against Misbeha)-.234 E(ving Nodes)-.325 E F0
(In this section we discuss the protection ag)100.8 579 Q
(ainst senders, recei)-.055 E -.165(ve)-.275 G
(rs, or colluding routers or).165 E(middlebox)100.8 592 Q
(es lying about the Quick-Start Request.)-.165 E F1 2.75(9.4.1. Misbeha)
72 631 R(ving Senders)-.275 E F0 2.75(At)100.8 657 S(ransport sender co\
uld try to transmit data at a higher rate than that appro)-2.75 E -.165
(ve)-.165 G 2.75(di).165 G 2.75(nt)-2.75 G(he)-2.75 E
(Quick-Start Request.)100.8 670 Q(The netw)5.5 E(ork could use a traf)
-.11 E(\214c policer to protect ag)-.275 E(ainst)-.055 E(misbeha)100.8
683 Q(ving senders that e)-.22 E(xceed the appro)-.165 E -.165(ve)-.165
G 2.75(dr).165 G(ate, for e)-2.75 E(xample by dropping pack)-.165 E
(ets that)-.11 E -.165(ex)100.8 696 S(ceed the allo).165 E
(wed transmission rate. The required Report of Appro)-.275 E -.165(ve)
-.165 G 2.75(dR).165 G(ate allo)-2.75 E(ws traf)-.275 E<8c63>-.275 E
(policers to check that the Report of Appro)100.8 709 Q -.165(ve)-.165 G
2.75(dR).165 G(ate does not e)-2.75 E(xceed the Rate Request)-.165 E
(actually appro)100.8 722 Q -.165(ve)-.165 G 2.75(da).165 G 2.75(tt)
-2.75 G(hat point in the netw)-2.75 E(ork in the pre)-.11 E
(vious Quick-Start Request from that)-.275 E(Flo)72 769 Q 195.775
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.4.1. [P)2.75 F(age 40])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E 2.75(connection. The)100.8 85
R(required Appro)2.75 E -.165(ve)-.165 G 2.75(dR).165 G
(ate report also allo)-2.75 E(ws traf)-.275 E
(\214c policers to check that)-.275 E(the sender')100.8 98 Q 2.75(ss)
-.605 G(ending rate does not e)-2.75 E
(xceed the rate in the Report of Appro)-.165 E -.165(ve)-.165 G 2.75(dR)
.165 G(ate.)-2.75 E(If a router or recei)100.8 124 Q -.165(ve)-.275 G
2.75(rr).165 G(ecei)-2.75 E -.165(ve)-.275 G 2.75(sa).165 G 2.75(nA)
-2.75 G(ppro)-2.75 E -.165(ve)-.165 G 2.75(dR).165 G
(ate report that is lar)-2.75 E(ger than the Rate Request)-.198 E
(in the Quick-Start request appro)100.8 137 Q -.165(ve)-.165 G 2.75(df)
.165 G(or that sender for that connection in the pre)-2.75 E(vious)-.275
E(round-trip time, then the router or recei)100.8 150 Q -.165(ve)-.275 G
2.75(rc).165 G(ould den)-2.75 E 2.75(yf)-.165 G
(uture Quick-Start requests from that)-2.75 E(sender)100.8 163 Q 2.75
(,e)-.44 G(.g., by deleting the Quick-Start Request from future pack)
-2.75 E(ets from that sender)-.11 E 5.5(.W)-.605 G(e)-6.38 E
(note that routers are not required to use Appro)100.8 176 Q -.165(ve)
-.165 G 2.75(dR).165 G(ate reports to check if senders are)-2.75 E
(cheating; this is at the discretion of the router)100.8 189 Q(.)-.605 E
(If a router sees a Report of Appro)100.8 215 Q -.165(ve)-.165 G 2.75
(dR).165 G(ate, and did not see an earlier Quick-Start request,)-2.75 E
(then either the sender could be cheating, or the connection')100.8 228
Q 2.75(sp)-.605 G(ath could ha)-2.75 E .33 -.165(ve c)-.22 H
(hanged since).165 E(the Quick-Start request w)100.8 241 Q(as sent.)-.11
E(In either case, the router could decide to den)5.5 E 2.75(yf)-.165 G
(uture)-2.75 E(Quick-Start requests for this connection.)100.8 254 Q
(In particular)5.5 E 2.75(,i)-.44 G 2.75(ti)-2.75 G 2.75(sr)-2.75 G
(easonable for the router to)-2.75 E(den)100.8 267 Q 2.75(yaQ)-.165 G(u\
ick-Start request if either the sender is cheating, or if the connectio\
n path suf)-2.75 E(fers)-.275 E(from path changes or multipathing.)100.8
280 Q(If a router appro)100.8 306 Q -.165(ve)-.165 G 2.75(daQ).165 G
(uick-Start Request, b)-2.75 E(ut does not see a subsequent Appro)-.22 E
-.165(ve)-.165 G 2.75(dR).165 G(ate)-2.75 E(report, then there are se)
100.8 319 Q -.165(ve)-.275 G(ral possibilities: \(1\) the request w).165
E(as denied and/or dropped)-.11 E(do)100.8 332 Q
(wnstream and the sender did not send a Report of Appro)-.275 E -.165
(ve)-.165 G 2.75(dR).165 G(ate; \(2\) the request w)-2.75 E(as)-.11 E
(appro)100.8 345 Q -.165(ve)-.165 G 2.75(db).165 G
(ut the sender did not send a Report of Appro)-2.97 E -.165(ve)-.165 G
2.75(dR).165 G(ate; \(3\) the Appro)-2.75 E -.165(ve)-.165 G 2.75(dR)
.165 G(ate)-2.75 E(report w)100.8 358 Q(as dropped in the netw)-.11 E
(ork; or \(4\) the Appro)-.11 E -.165(ve)-.165 G 2.75(dR).165 G
(ate report took a dif)-2.75 E(ferent path)-.275 E
(from the Quick-Start Request.)100.8 371 Q(In an)5.5 E 2.75(yo)-.165 G
2.75(ft)-2.75 G(hese cases, the router w)-2.75 E(ould be justi\214ed in)
-.11 E(den)100.8 384 Q
(ying future Quick-Start Requests for this connection.)-.165 E(In an)
100.8 410 Q 2.75(yo)-.165 G 2.75(ft)-2.75 G
(he cases mentioned in the three paragraphs abo)-2.75 E .33 -.165(ve \()
-.165 H(i.e., an Appro).165 E -.165(ve)-.165 G 2.75(dR).165 G
(ate report)-2.75 E(that is lar)100.8 423 Q(ger than the Rate Request i\
n the earlier Quick-Start request; a Report of Appro)-.198 E -.165(ve)
-.165 G(d).165 E(Rate with no preceding Rate Request, or a Rate Request\
 with no Report of Appro)100.8 436 Q -.165(ve)-.165 G(d).165 E
(Rate\), a traf)100.8 449 Q(\214c policer may assume that Quick-Start i\
s not being used appropriately)-.275 E 2.75(,o)-.715 G 2.75(ri)-2.75 G
(s)-2.75 E(being used in an unsuitable en)100.8 462 Q
(vironment \(e.g., with multiple paths\), and tak)-.44 E 2.75(es)-.11 G
(ome)-2.75 E(corresponding action.)100.8 475 Q(What are the incenti)
100.8 501 Q -.165(ve)-.275 G 2.75(sf).165 G(or a sender to cheat by o)
-2.75 E -.165(ve)-.165 G -.22(r-).165 G
(sending after a Quick-Start request?).22 E(Assuming that the sender')
100.8 514 Q 2.75(si)-.605 G
(nterests are measured by a performance metric such as the)-2.75 E(comp\
letion time for its connections, sometimes it might be in the sender')
100.8 527 Q 2.75(si)-.605 G(nterests to)-2.75 E
(cheat, and sometimes it might not;)100.8 540 Q
(in some cases it could be dif)5.5 E(\214cult for the sender to)-.275 E
(judge whether it w)100.8 553 Q(ould be in its interests to cheat.)-.11
E(The incenti)5.5 E -.165(ve)-.275 G 2.75(sf).165 G
(or a sender to cheat by)-2.75 E -.165(ove)100.8 566 S -.22(r-).165 G
(sending after a Quick-Start request are not that dif).22 E
(ferent from the incenti)-.275 E -.165(ve)-.275 G 2.75(sf).165 G(or a)
-2.75 E(sender to cheat by o)100.8 579 Q -.165(ve)-.165 G -.22(r-).165 G
(sending e).22 E -.165(ve)-.275 G 2.75(ni).165 G 2.75(nt)-2.75 G
(he absence of Quick-Start, with one dif)-2.75 E(ference:)-.275 E
(the use of Quick-Start could help a sender to e)100.8 592 Q -.275(va)
-.275 G(de policing actions from policers in the).275 E(netw)100.8 605 Q
2.75(ork. The)-.11 F(Report of Appro)2.75 E -.165(ve)-.165 G 2.75(dR)
.165 G(ate is designed to address this, to mak)-2.75 E 2.75(ei)-.11 G
2.75(th)-2.75 G(arder to)-2.75 E(senders to use Quick-Start to `co)100.8
618 Q -.165(ve)-.165 G(r' their cheating.).165 E/F1 11/Times-Bold@0 SF
2.75(9.4.2. Recei)72 657 R -.11(ve)-.11 G(rs L).11 E
(ying about Whether the Request was A)-.605 E(ppr)-.275 E -.11(ove)-.198
G(d).11 E F0(One form of misbeha)100.8 683 Q(vior w)-.22 E
(ould be for the recei)-.11 E -.165(ve)-.275 G 2.75(rt).165 G 2.75(ol)
-2.75 G(ie to the sender about whether the)-2.75 E
(Quick-Start Request w)100.8 696 Q(as appro)-.11 E -.165(ve)-.165 G
(d, by f).165 E(alsely reporting the TTL Dif)-.11 E 2.75(fa)-.275 G
(nd QS Nonce.)-2.75 E(If a)5.5 E(router that understands the Quick-Star\
t Request denies the request by deleting the request)100.8 709 Q
(or by zeroing the QS TTL and QS Nonce, then the recei)100.8 722 Q -.165
(ve)-.275 G 2.75(rc).165 G(an `)-2.75 E(`lie" about whether the)-.814 E
(Flo)72 769 Q 195.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(9.4.2. [P)2.75 F(age 41])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E(request w)100.8 85 Q(as appro)
-.11 E -.165(ve)-.165 G 2.75(do).165 G
(nly by successfully guessing the v)-2.75 E(alue of the TTL Dif)-.275 E
2.75(fa)-.275 G(nd QS)-2.75 E(Nonce to report.)100.8 98 Q
(The chance of the recei)5.5 E -.165(ve)-.275 G 2.75(rs).165 G
(uccessfully guessing the correct v)-2.75 E(alue for the)-.275 E
(TTL Dif)100.8 111 Q 2.75(fi)-.275 G 2.75(s1)-2.75 G
(/256, and the chance of the recei)-2.75 E -.165(ve)-.275 G 2.75(rs).165
G(uccessfully guessing the QS nonce for a)-2.75 E
(reported rate request of K is 1/\(2K\).)100.8 124 Q(Ho)100.8 150 Q(we)
-.275 E -.165(ve)-.275 G .88 -.44(r, i).165 H 2.75(ft).44 G(he Quick-St\
art request is denied only by a non-Quick-Start-capable router)-2.75 E
2.75(,o)-.44 G(r)-2.75 E(by a router that is unable to zero the QS TTL \
and QS Nonce \214elds, then the recei)100.8 163 Q -.165(ve)-.275 G 2.75
(rc).165 G(ould)-2.75 E
(lie about whether the Quick-Start Requests were appro)100.8 176 Q -.165
(ve)-.165 G 2.75(db).165 G 2.75(ym)-2.75 G(odifying the QS TTL in)-2.75
E(successi)100.8 189 Q .33 -.165(ve r)-.275 H(equests recei).165 E -.165
(ve)-.275 G 2.75(df).165 G(rom the same host.)-2.75 E(In particular)5.5
E 2.75(,i)-.44 G 2.75(ft)-2.75 G(he sender does not act on)-2.75 E 2.75
(aQ)100.8 202 S(uick-Start Request, then the recei)-2.75 E -.165(ve)
-.275 G 2.75(rc).165 G(ould decrement the QS TTL by one in the ne)-2.75
E(xt)-.165 E(request recei)100.8 215 Q -.165(ve)-.275 G 2.75(df).165 G
(rom that host before calculating the TTL Dif)-2.75 E
(f, and decrement the QS)-.275 E(TTL by tw)100.8 228 Q 2.75(oi)-.11 G
2.75(nt)-2.75 G(he follo)-2.75 E(wing recei)-.275 E -.165(ve)-.275 G
2.75(dr).165 G(equest, until the sender acts on one of the Quick-)-2.75
E(Start Requests.)100.8 241 Q(Unfortunately)100.8 267 Q 2.75(,i)-.715 G
2.75(far)-2.75 G(outer doesn')-2.75 E 2.75(tu)-.198 G
(nderstand Quick-Start, then it is not possible for that)-2.75 E
(router to tak)100.8 280 Q 2.75(ea)-.11 G 2.75(na)-2.75 G(cti)-2.75 E
.33 -.165(ve s)-.275 H
(tep such as zeroing the QS TTL and QS Nonce to den).165 E 2.75(yar)
-.165 G(equest.)-2.75 E(As a result, the QS TTL is not a f)100.8 293 Q
(ail-safe mechanism for pre)-.11 E -.165(ve)-.275 G
(nting lying by recei).165 E -.165(ve)-.275 G(rs in).165 E
(the case of non-Quick-Start-capable routers.)100.8 306 Q(What w)100.8
332 Q(ould be the incenti)-.11 E -.165(ve)-.275 G 2.75(sf).165 G
(or a recei)-2.75 E -.165(ve)-.275 G 2.75(rt).165 G 2.75(oc)-2.75 G
(heat in reporting on a Quick-Start request,)-2.75 E
(in the absence of a mechanism such as the QS Nonce?)100.8 345 Q
(In some cases, cheating w)5.5 E(ould ha)-.11 E -.165(ve)-.22 G
(been of clear bene\214t to the recei)100.8 358 Q -.165(ve)-.275 G .88
-.44(r, r).165 H(esulting in a f).44 E
(aster completion time for the transfer)-.11 E(.)-.605 E
(In other cases, where cheating w)100.8 371 Q(ould ha)-.11 E .33 -.165
(ve r)-.22 H(esulted in Quick-Start pack).165 E(ets being dropped in)
-.11 E(the netw)100.8 384 Q(ork, cheating might or might not ha)-.11 E
.33 -.165(ve i)-.22 H(mpro).165 E -.165(ve)-.165 G 2.75(dt).165 G
(he recei)-2.75 E -.165(ve)-.275 G(r').165 E 2.75(sp)-.605 G
(erformance metric,)-2.75 E
(depending on the details of that particular scenario.)100.8 397 Q/F1 11
/Times-Bold@0 SF 2.75(9.4.3. Recei)72 436 R -.11(ve)-.11 G(rs L).11 E
(ying about the A)-.605 E(ppr)-.275 E -.11(ove)-.198 G 2.75(dR).11 G
(ate)-2.75 E F0 2.75(As)100.8 462 S(econd form of recei)-2.75 E -.165
(ve)-.275 G 2.75(rm).165 G(isbeha)-2.75 E(vior w)-.22 E
(ould be for the recei)-.11 E -.165(ve)-.275 G 2.75(rt).165 G 2.75(ol)
-2.75 G(ie to the sender about)-2.75 E(the Rate Request for an appro)
100.8 475 Q -.165(ve)-.165 G 2.75(dQ).165 G
(uick-Start Request, by increasing the v)-2.75 E(alue of the Rate)-.275
E(Request \214eld.)100.8 488 Q(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88
-.44(r, t).165 H(he recei).44 E -.165(ve)-.275 G 2.75(rd).165 G(oesn')
-2.75 E 2.75(tn)-.198 G(ecessarily kno)-2.75 E 2.75(wt)-.275 G
(he Rate Request in the)-2.75 E
(original Quick-Start Request sent by the sender)100.8 501 Q 2.75(,a)
-.44 G(nd a higher Rate Request reported by the)-2.75 E(recei)100.8 514
Q -.165(ve)-.275 G 2.75(rw).165 G(ill only be considered v)-2.75 E
(alid by the sender if it is no higher than the Rate Request)-.275 E
(originally requested by the sender)100.8 527 Q 5.5(.F)-.605 G(or e)
-5.665 E(xample, if the sender sends a Quick-Start Request)-.165 E
(with a Rate Request of X, and the recei)100.8 540 Q -.165(ve)-.275 G
2.75(rr).165 G(eports recei)-2.75 E(ving a Quick-Start Request with a)
-.275 E(Rate Request of Y > X, then the sender kno)100.8 553 Q
(ws that either some router along the path)-.275 E(malfunctioned \(incr\
easing the Rate Request inappropriately\), or the recei)100.8 566 Q
-.165(ve)-.275 G 2.75(ri).165 G 2.75(sl)-2.75 G(ying about)-2.75 E
(the Rate Request in the recei)100.8 579 Q -.165(ve)-.275 G 2.75(dp).165
G(ack)-2.75 E(et.)-.11 E(If the sender sends a Quick-Start Request with\
 a Rate Request of Z, the recei)100.8 605 Q -.165(ve)-.275 G 2.75(rr)
.165 G(ecei)-2.75 E -.165(ve)-.275 G(s).165 E
(the Quick-Start Request with an appro)100.8 618 Q -.165(ve)-.165 G 2.75
(dR).165 G(ate Request of X, and reports a Rate Request)-2.75 E(of Y)
100.8 631 Q 2.75(,f)-1.419 G(or X < Y <= Z, then the recei)-2.75 E -.165
(ve)-.275 G 2.75(ro).165 G
(nly succeeds in lying to the sender about the)-2.75 E(appro)100.8 644 Q
-.165(ve)-.165 G 2.75(dr).165 G(ate if the recei)-2.75 E -.165(ve)-.275
G 2.75(rs).165 G
(uccessfully reports the rightmost 2Y bits in the QS nonce.)-2.75 E
(If senders often use a con\214gured def)100.8 670 Q(ault v)-.11 E
(alue for the Rate Request, then recei)-.275 E -.165(ve)-.275 G(rs w)
.165 E(ould)-.11 E
(often be able to guess the original Rate Request, and this w)100.8 683
Q(ould mak)-.11 E 2.75(ei)-.11 G 2.75(te)-2.75 G(asier for the)-2.75 E
(recei)100.8 696 Q -.165(ve)-.275 G 2.75(rt).165 G 2.75(ol)-2.75 G
(ie about the v)-2.75 E(alue of the Rate Request \214eld.)-.275 E
(Similarly)5.5 E 2.75(,i)-.715 G 2.75(ft)-2.75 G(he recei)-2.75 E -.165
(ve)-.275 G 2.75(ro).165 G(ften)-2.75 E
(communicates with a particular sender)100.8 709 Q 2.75(,a)-.44 G
(nd the sender al)-2.75 E -.11(wa)-.11 G(ys uses the same Rate Request)
.11 E(for that recei)100.8 722 Q -.165(ve)-.275 G .88 -.44(r, t).165 H
(hen the recei).44 E -.165(ve)-.275 G 2.75(rm).165 G(ight o)-2.75 E
-.165(ve)-.165 G 2.75(rt).165 G(ime be able to infer the original Rate)
-2.75 E(Flo)72 769 Q 195.775(yd/Allman/Jain/Sarolahti Section)-.11 F
2.75(9.4.3. [P)2.75 F(age 42])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(Request used by the sender)
100.8 85 Q(.)-.605 E(There are se)100.8 111 Q -.165(ve)-.275 G
(ral possible additional forms of protection ag).165 E(ainst recei)-.055
E -.165(ve)-.275 G(rs lying about the).165 E -.275(va)100.8 124 S
(lue of the Rate Request.).275 E(One possible additional protection w)
5.5 E(ould be for a router that)-.11 E(decreases a Rate Request in a Qu\
ick-Start Request to report the decrease directly to the)100.8 137 Q
(sender)100.8 150 Q 5.5(.H)-.605 G -.275(ow)-5.5 G -2.365 -.275(ev e)
.275 H .88 -.44(r, t).275 H(his could lead to man).44 E 2.75(yr)-.165 G
(eports back to the sender for a single request,)-2.75 E
(and could also be used in address-spoo\214ng attacks.)100.8 163 Q 2.75
(As)100.8 189 S(econd limited form of protection w)-2.75 E
(ould be for senders to use some de)-.11 E(gree of)-.165 E
(randomization in the requested Rate Request, so that it is dif)100.8
202 Q(\214cult for recei)-.275 E -.165(ve)-.275 G(rs to guess the).165 E
(original v)100.8 215 Q(alue for the Rate Request.)-.275 E(Ho)5.5 E(we)
-.275 E -.165(ve)-.275 G .88 -.44(r, t).165 H(his is dif).44 E
(\214cult because there is a f)-.275 E(airly)-.11 E
(coarse granularity in the set of rate requests a)100.8 228 Q -.275(va)
-.22 G(ilable to the sender).275 E 2.75(,a)-.44 G(nd randomizing the)
-2.75 E(initial request only of)100.8 241 Q
(fers limited protection in an)-.275 E 2.75(yc)-.165 G(ase.)-2.75 E/F1
11/Times-Bold@0 SF 2.75(9.4.4. Collusion)72 280 R(between Misbeha)2.75 E
(ving Routers)-.275 E F0(In addition to protecting ag)100.8 306 Q
(ainst misbeha)-.055 E(ving recei)-.22 E -.165(ve)-.275 G
(rs, it is necessary also to protect).165 E(ag)100.8 319 Q
(ainst misbeha)-.055 E(ving routers.)-.22 E
(Consider collusion between an ingress router and an e)5.5 E(gress)-.165
E(router belonging to the same Intranet.)100.8 332 Q
(The ingress router could decrement the Rate)5.5 E
(Request at the ingress, with the e)100.8 345 Q
(gress router increasing it ag)-.165 E(ain at the e)-.055 E 2.75
(gress. The)-.165 F(routers)2.75 E(between the ingress and e)100.8 358 Q
(gress that appro)-.165 E -.165(ve)-.165 G 2.75(dt).165 G
(he decremented rate request might not ha)-2.75 E -.165(ve)-.22 G
(been willing to appro)100.8 371 Q .33 -.165(ve t)-.165 H(he lar).165 E
(ger)-.198 E 2.75(,o)-.44 G(riginal request.)-2.75 E
(Another form of collusion w)100.8 397 Q
(ould be for the ingress router to inform the e)-.11 E
(gress router out-)-.165 E(of-band of the TTL Dif)100.8 410 Q 2.75(fa)
-.275 G(nd QS Nonce for the request pack)-2.75 E(et at the ingress.)-.11
E(This w)5.5 E(ould)-.11 E(enable the e)100.8 423 Q(gress router to mod\
ify the QS TTL and QS Nonce so that it appeared that all of)-.165 E
(the routers along the path had appro)100.8 436 Q -.165(ve)-.165 G 2.75
(dt).165 G(he request.)-2.75 E(There does not appear to be an)5.5 E(y)
-.165 E(protection ag)100.8 449 Q(ainst a colluding ingress and e)-.055
E(gress router)-.165 E 5.5(.E)-.605 G -.165(ve)-5.5 G 2.75(ni).165 G
2.75(fa)-2.75 G 2.75(ni)-2.75 G(ntermediate router had)-2.75 E
(deleted the Quick-Start Option from the pack)100.8 462 Q
(et, the ingress router could ha)-.11 E .33 -.165(ve s)-.22 H(ent the)
.165 E(Quick-Start Option to the e)100.8 475 Q
(gress router out-of-band, with the e)-.165 E
(gress router inserting the)-.165 E
(Quick-Start Option, with a modi\214ed QS TTL \214eld, back in the pack)
100.8 488 Q(et.)-.11 E(Ho)100.8 514 Q(we)-.275 E -.165(ve)-.275 G .88
-.44(r, u).165 H(nlik).44 E 2.75(eE)-.11 G(CN, there is some)-2.75 E
(what less incenti)-.275 E .33 -.165(ve f)-.275 H
(or cooperating ingress and e).165 E(gress)-.165 E
(routers to collude to f)100.8 527 Q
(alsely modify the Quick-Start Request so that it appears to ha)-.11 E
.33 -.165(ve b)-.22 H(een).165 E(appro)100.8 540 Q -.165(ve)-.165 G 2.75
(db).165 G 2.75(ya)-2.75 G(ll of the routers along the path.)-2.75 E
-.44(Wi)5.5 G(th ECN, a colluding ingress router could).44 E -.11(fa)
100.8 553 S(lsely mark a pack).11 E
(et as ECN-capable, with the colluding e)-.11 E
(gress router returning the ECN)-.165 E(\214eld in the IP header to its\
 original non-ECN-capable codepoint, and congested routers)100.8 566 Q
(along the path could ha)100.8 579 Q .33 -.165(ve b)-.22 H
(een fooled into not dropping that pack).165 E 2.75(et. This)-.11 F
(collusion w)2.75 E(ould)-.11 E(gi)100.8 592 Q .33 -.165(ve a)-.275 H
2.75(nu).165 G(nf)-2.75 E(air competiti)-.11 E .33 -.165(ve a)-.275 H
(dv).165 E(antage to the traf)-.275 E
(\214c protected by the colluding ingress and)-.275 E -.165(eg)100.8 605
S(ress routers.).165 E
(In contrast, with Quick-Start, the collusion of the ingress and e)100.8
631 Q(gress routers to mak)-.165 E 2.75(ei)-.11 G(t)-2.75 E -.11(fa)
100.8 644 S(lsely appear that a Quick-Start request w).11 E(as appro)
-.11 E -.165(ve)-.165 G 2.75(ds).165 G(ometimes could gi)-2.75 E .33
-.165(ve a)-.275 H 2.75(na).165 G(dv)-2.75 E(antage)-.275 E(to the traf)
100.8 657 Q(\214c co)-.275 E -.165(ve)-.165 G
(red by that collusion, and sometimes w).165 E(ould gi)-.11 E .33 -.165
(ve a d)-.275 H(isadv).165 E(antage,)-.275 E
(depending on the details of the scenario.)100.8 670 Q
(If some router along the path really does not ha)5.5 E -.165(ve)-.22 G
(enough a)100.8 683 Q -.275(va)-.22 G(ilable bandwidth to appro).275 E
.33 -.165(ve t)-.165 H(he Quick-Start request, then Quick-Start pack)
.165 E(ets)-.11 E(sent as a result of the f)100.8 696 Q(alsely-appro)
-.11 E -.165(ve)-.165 G 2.75(dr).165 G
(equest could be dropped in the netw)-2.75 E(ork, to the)-.11 E
(possible disadv)100.8 709 Q(antage of the connection.)-.275 E
(Thus, while the ingress and e)5.5 E(gress routers could)-.165 E
(collude to pre)100.8 722 Q -.165(ve)-.275 G
(nt intermediate routers from den).165 E
(ying a Quick-Start request, it w)-.165 E(ould not)-.11 E(Flo)72 769 Q
195.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.4.4. [P)2.75 F
(age 43])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E(al)100.8 85 Q -.11(wa)-.11 G
(ys be to the connection').11 E 2.75(sa)-.605 G(dv)-2.75 E
(antage for this to happen.)-.275 E(One defense ag)5.5 E(ainst such a)
-.055 E(collusion w)100.8 98 Q
(ould be for some router between the ingress and e)-.11 E
(gress nodes that denied the)-.165 E(request to monitor connection perf\
ormance, penalizing connections that seeem to be using)100.8 111 Q
(Quick-Start after a Quick-Start request w)100.8 124 Q
(as denied, or that are reporting an Appro)-.11 E -.165(ve)-.165 G 2.75
(dR).165 G(ate)-2.75 E(higher than that actually appro)100.8 137 Q -.165
(ve)-.165 G 2.75(db).165 G 2.75(yt)-2.75 G(hat router)-2.75 E(.)-.605 E
(If the congested router is ECN-capable, and the colluding ingress and \
e)100.8 163 Q(gress routers are)-.165 E(lying about ECN-capability as w\
ell as about Quick-Start, then the result could be that the)100.8 176 Q
(Quick-Start request f)100.8 189 Q(alsely appears to the sender to ha)
-.11 E .33 -.165(ve b)-.22 H(een appro).165 E -.165(ve)-.165 G
(d, and the Quick-).165 E(Start pack)100.8 202 Q(ets f)-.11 E
(alsely appear to the congested router to be ECN-capable.)-.11 E
(In this case, the)5.5 E(colluding routers might succeed in gi)100.8 215
Q(ving a competiti)-.275 E .33 -.165(ve a)-.275 H(dv).165 E
(antage to the traf)-.275 E(\214c protected)-.275 E(by their collusion \
\(if no intermediate router is monitoring to catch such misbeha)100.8
228 Q(vior\).)-.22 E/F1 11/Times-Bold@0 SF(9.5.)72 267 Q/F2 13
/Times-Bold@0 SF(Misbeha)5.5 E(ving Middleboxes and the IP TTL)-.325 E
F0(One possible dif)100.8 293 Q(\214culty is that of traf)-.275 E
(\214c normalizers [HKP01] or other middlebox)-.275 E(es along)-.165 E(\
that path that re-write IP TTLs in order to foil other kinds of attacks\
 in the netw)100.8 306 Q 2.75(ork. If)-.11 F(such)2.75 E 2.75(at)100.8
319 S(raf)-2.75 E(\214c normalizer re-wrote the IP TTL, b)-.275 E
(ut did not adjust the Quick-Start TTL by the)-.22 E
(same amount, then the sender')100.8 332 Q 2.75(sm)-.605 G
(echanism for determining if the request w)-2.75 E(as appro)-.11 E -.165
(ve)-.165 G 2.75(db).165 G(y)-2.75 E(all routers along the path w)100.8
345 Q(ould no longer be reliable.)-.11 E
(Re-writing the IP TTL could result)5.5 E(in f)100.8 358 Q(alse positi)
-.11 E -.165(ve)-.275 G 2.75(s\().165 G
(with the sender incorrectly belie)-2.75 E
(ving that the Quick-Start request w)-.275 E(as)-.11 E(appro)100.8 371 Q
-.165(ve)-.165 G(d\) as well as f).165 E(alse ne)-.11 E -.055(ga)-.165 G
(ti).055 E -.165(ve)-.275 G 2.75(s\().165 G
(with the sender incorrectly belie)-2.75 E(ving that the Quick-)-.275 E
(Start request w)100.8 384 Q(as denied\).)-.11 E F1(9.6.)72 423 Q F2
(Attacks on Quick-Start)5.5 E F0
(As discussed in [SAF06], Quick-Start is vulnerable to tw)100.8 449 Q
2.75(ok)-.11 G(inds of attacks:)-2.75 E(\(1\) attacks to)5.5 E(increase\
 the routers' processing and state load; and \(2\) attacks with bogus Q\
uick-Start)100.8 462 Q(requests to temporarily tie up a)100.8 475 Q
-.275(va)-.22 G(ilable Quick-Start bandwidth, pre).275 E -.165(ve)-.275
G(nting routers from).165 E(appro)100.8 488 Q
(ving Quick-Start requests from other connections.)-.165 E
(Routers can protect ag)5.5 E(ainst the)-.055 E(\214rst kind of attack \
by applying a simple limit on the rate at which Quick-Start requests wi\
ll)100.8 501 Q(be considered by the router)100.8 514 Q(.)-.605 E
(The second kind of attack, to tie up the a)100.8 540 Q -.275(va)-.22 G
(ilable Quick-Start bandwidth, is more dif).275 E(\214cult)-.275 E
(to defend ag)100.8 553 Q 2.75(ainst. As)-.055 F
(discussed in [SAF06]. Quick-Start Requests that are not going to be)
2.75 E(used, either because the)100.8 566 Q 2.75(ya)-.165 G
(re from malicious attack)-2.75 E(ers or because the)-.11 E 2.75(ya)
-.165 G(re denied by)-2.75 E(routers do)100.8 579 Q
(wnstream, can result in short-term `w)-.275 E
(asting' potential Quick-Start bandwidth,)-.11 E
(resulting in routers den)100.8 592 Q
(ying subsequent Quick-Start Requests that if appro)-.165 E -.165(ve)
-.165 G 2.75(dw).165 G(ould in f)-2.86 E(act)-.11 E(ha)100.8 605 Q .33
-.165(ve b)-.22 H(een used.).165 E 1.76 -.88(We n)5.5 H
(ote that the lik).88 E(elihood of malicious attacks w)-.11 E
(ould be minimized)-.11 E(signi\214cantly when Quick-Start w)100.8 618 Q
(as deplo)-.11 E(yed in a controlled en)-.11 E(vironment such as an)-.44
E(Intranet, where there w)100.8 631 Q
(as some form of centralized control o)-.11 E -.165(ve)-.165 G 2.75(rt)
.165 G(he users in the system.)-2.75 E 1.76 -.88(We a)100.8 644 T
(lso note that this form of attack could potentially mak).88 E 2.75(eQ)
-.11 G(uick-Start unusable, b)-2.75 E(ut it)-.22 E -.11(wo)100.8 657 S
(uld not do an).11 E 2.75(yf)-.165 G(urther damage; in the w)-2.75 E
(orst case, the netw)-.11 E(ork w)-.11 E(ould function as a)-.11 E(netw)
100.8 670 Q(ork without Quick-Start.)-.11 E([SAF06] considers the poten\
tial of Extreme Quick-Start algorithms at routers, which k)100.8 696 Q
(eep)-.11 E(per)100.8 709 Q(-\215o)-.22 E 2.75(ws)-.275 G
(tate for Quick-Start connections, in protecting the a)-2.75 E -.275(va)
-.22 G(ilability of Quick-Start).275 E(bandwidth in the f)100.8 722 Q
(ace of frequent o)-.11 E -.165(ve)-.165 G(rly-lar).165 E
(ge Quick-Start requests.)-.198 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.6. [P)2.75 F(age 44])
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(April 2007)2.75 E(October 2006)112.127 E/F1 11/Times-Bold@0 SF(9.7.)72
85 Q/F2 13/Times-Bold@0 SF(Simulations with Quick-Start)5.5 E F0
(Quick-Start w)100.8 111 Q(as added to the NS simulator [SH02] by Srika\
nth Sundarrajan, and additional)-.11 E(functionality w)100.8 124 Q
(as added by P)-.11 E(asi Sarolahti.)-.165 E(The v)5.5 E
(alidation test is at `test-all-quickstart' in)-.275 E
(the `tcl/test' directory in NS.)100.8 137 Q
(The initial simulation studies from [SH02] sho)5.5 E 2.75(was)-.275 G
(igni\214cant)-2.75 E(performance impro)100.8 150 Q -.165(ve)-.165 G
(ment using Quick-Start for moderate-sized \215o).165 E
(ws \(between 4KB and)-.275 E(128KB\) in under)100.8 163 Q(-utilized en)
-.22 E 2.75(vironments. These)-.44 F
(studies are of \214le transfers, with the)2.75 E(impro)100.8 176 Q
-.165(ve)-.165 G(ment measured as the relati).165 E .33 -.165(ve i)-.275
H(ncrease in the o).165 E -.165(ve)-.165 G
(rall throughput for the \214le).165 E(transfer)100.8 189 Q 5.5(.T)-.605
G(he study sho)-5.5 E(ws that potential impro)-.275 E -.165(ve)-.165 G
(ment from Quick-Start is proportional to).165 E
(the delay-bandwidth product of the path.)100.8 202 Q
(The Quick-Start simulations in [SAF06] e)100.8 228 Q(xplore the follo)
-.165 E(wing: the potential bene\214t of)-.275 E
(Quick-Start for the connection; the relati)100.8 241 Q .33 -.165(ve b)
-.275 H(ene\214ts of dif).165 E(ferent router)-.275 E
(-based algorithms for)-.22 E(appro)100.8 254 Q
(ving Quick-Start requests; and the ef)-.165 E(fecti)-.275 E -.165(ve)
-.275 G(ness of Quick-Start as a function of the).165 E
(senders' algorithms for choosing the size of the rate request.)100.8
267 Q F1(10.)72 306 Q/F3 14/Times-Bold@0 SF
(Implementation and Deployment Issues)5.5 E F0(This section discusses s\
ome of the implementation issues with Quick-Start.)100.8 332 Q
(This section)8.25 E(also discusses some of the k)100.8 345 Q .33 -.165
(ey d)-.11 H(eplo).165 E(yment issues, such as the chick)-.11 E
(en-and-e)-.11 E(gg deplo)-.165 E(yment)-.11 E
(problems of mechanisms that ha)100.8 358 Q .33 -.165(ve t)-.22 H 2.75
(ob).165 G 2.75(ed)-2.75 G(eplo)-2.75 E
(yed in both routers and end nodes in order to)-.11 E -.11(wo)100.8 371
S(rk, and the problems posed by the wide deplo).11 E(yment of middlebox)
-.11 E(es today that block the)-.165 E(use of kno)100.8 384 Q
(wn or unkno)-.275 E(wn IP Options.)-.275 E F1(10.1.)72 423 Q F2
(Implementation Issues f)5.5 E(or Sending Quick-Start Requests)-.325 E
F0(Section 4.7 discusses some of the issues with deciding the initial s\
ending rate to request.)100.8 449 Q(Quick-Start raises additional issue\
s about the communication between the transport)100.8 462 Q(protocol an\
d the application, and about the use of the past history with Quick-Sta\
rt in the)100.8 475 Q(end node.)100.8 488 Q
(One possibility is that a protocol implementation could pro)100.8 514 Q
(vide an API for applications to)-.165 E(indicate when the)100.8 527 Q
2.75(yw)-.165 G(ant to request Quick-Start, and what rate the)-2.86 E
2.75(yw)-.165 G(ould lik)-2.86 E 2.75(et)-.11 G 2.75(or)-2.75 G(equest.)
-2.75 E(In the con)100.8 540 Q -.165(ve)-.44 G(ntional sock).165 E
(et API this could be a sock)-.11 E
(et option that is set before a connection)-.11 E(is established.)100.8
553 Q(Some applications, such as those that use TCP for b)5.5 E
(ulk transfers, do not)-.22 E(ha)100.8 566 Q .33 -.165(ve i)-.22 H
(nterest in the transmission rate, b).165 E(ut the)-.22 E 2.75(ym)-.165
G(ight kno)-2.75 E 2.75(wt)-.275 G(he amount of data that can be)-2.75 E
(sent immediately)100.8 579 Q 2.75(.B)-.715 G
(ased on this, the sender implementation could decide whether Quick-)
-2.75 E(Start w)100.8 592 Q
(ould be useful, and what rate should be requested.)-.11 E 1.76 -.88
(We n)100.8 618 T
(ote that when Quick-Start is used, the TCP sender is required to sa).88
E .33 -.165(ve t)-.22 H(he QS Nonce).165 E(and the TTL Dif)100.8 631 Q
2.75(fw)-.275 G
(hen the Quick-Start request is sent, and to implement an additional)
-2.75 E(timer for the paced transmission of Quick-Start pack)100.8 644 Q
(ets.)-.11 E F1(10.2.)72 683 Q F2(Implementation Issues f)5.5 E(or Pr)
-.325 E(ocessing Quick-Start Requests)-.234 E F0 2.75(Ar)100.8 709 S
(outer or other netw)-2.75 E
(ork host must be able to determine the approximate bandwidth of its)
-.11 E(outbound netw)100.8 722 Q(ork interf)-.11 E
(aces in order to process incoming Quick-Start rate requests,)-.11 E
(Flo)72 769 Q 198.525(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(10.2. [P)2.75 F(age 45])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
(including those that originate from the host itself.)100.8 85 Q
(One possibility w)5.5 E(ould be for hosts to)-.11 E(rely on con\214gur\
ation information to determine link bandwidths; this has the dra)100.8
98 Q(wback of)-.165 E(not being rob)100.8 111 Q
(ust to errors in con\214guration.)-.22 E(Another possibility w)5.5 E
(ould be for netw)-.11 E(ork)-.11 E(de)100.8 124 Q(vice dri)-.275 E
-.165(ve)-.275 G(rs to infer the bandwidth for the interf).165 E
(ace and to communicate this to the IP)-.11 E(layer)100.8 137 Q(.)-.605
E -.165(Pa)100.8 163 S
(rticular issues will arise for wireless links with v).165 E
(ariable bandwidth, where decisions will)-.275 E(ha)100.8 176 Q .33
-.165(ve t)-.22 H 2.75(ob).165 G 2.75(em)-2.75 G(ade about ho)-2.75 E
2.75(wf)-.275 G
(requently the host gets updates of the changing bandwidth.)-2.75 E(It)
5.5 E(seems appropriate that Quick-Start Requests w)100.8 189 Q
(ould be handled particularly conserv)-.11 E(ati)-.275 E -.165(ve)-.275
G(ly).165 E(for links with v)100.8 202 Q(ariable bandwidth, to a)-.275 E
-.22(vo)-.22 G(id cases where Quick-Start Requests are appro).22 E -.165
(ve)-.165 G(d,).165 E(the link bandwidth is reduced, and the data pack)
100.8 215 Q(ets that are sent end up being dropped.)-.11 E(Dif)100.8 241
Q(\214cult issues also arise for paths with multi-access links \(e.g., \
Ethernet\).)-.275 E(Routers or end-)5.5 E
(nodes with multi-access links should be particularly conserv)100.8 254
Q(ati)-.275 E .33 -.165(ve i)-.275 H 2.75(ng).165 G(ranting Quick-Start)
-2.75 E 2.75(requests. In)100.8 267 R(particular)2.75 E 2.75(,f)-.44 G
(or some multi-access links there may be no procedure for an)-2.75 E(at\
tached node to use to determine whether all parts of the multi-access l\
ink ha)100.8 280 Q .33 -.165(ve b)-.22 H(een).165 E
(underutilized in the recent past.)100.8 293 Q/F1 11/Times-Bold@0 SF
(10.3.)72 332 Q/F2 13/Times-Bold@0 SF -.26(Po)5.5 G
(ssible Deployment Scenarios).26 E F0
(Because of possible problems discussed abo)100.8 358 Q .33 -.165(ve c)
-.165 H(oncerning using Quick-Start o).165 E -.165(ve)-.165 G 2.75(rs)
.165 G(ome)-2.75 E(netw)100.8 371 Q(ork paths and the security issues d\
iscussed in section 11, the most realistic initial)-.11 E(deplo)100.8
384 Q(yment of Quick-Start w)-.11 E(ould most lik)-.11 E(ely tak)-.11 E
2.75(ep)-.11 G(lace in Intranets and other controlled)-2.75 E(en)100.8
397 Q 2.75(vironments. Quick-Start)-.44 F
(is most useful on high bandwidth-delay paths that are)2.75 E(signi\214\
cantly underutilized. The primary initial users of Quick-Start w)100.8
410 Q(ould lik)-.11 E(ely be in)-.11 E(or)100.8 423 Q -.055(ga)-.198 G
(nizations that pro).055 E(vide netw)-.165 E
(ork services to their users and also ha)-.11 E .33 -.165(ve c)-.22 H
(ontrol o).165 E -.165(ve)-.165 G 2.75(ral).165 G(ar)-2.75 E(ge)-.198 E
(portion of the netw)100.8 436 Q(ork path.)-.11 E
(Quick-Start is not currently intended for ubiquitous deplo)100.8 462 Q
(yment in the global Internet.)-.11 E(In)5.5 E(particular)100.8 475 Q
2.75(,Q)-.44 G(uick-Start should not be enabled by def)-2.75 E
(ault in end-nodes or in routers; instead,)-.11 E
(when Quick-Start is used, it should be e)100.8 488 Q
(xplicitly enabled by users or system administrators.)-.165 E(Belo)100.8
514 Q 2.75(wa)-.275 G(re a fe)-2.75 E 2.75(we)-.275 G(xamples of netw)
-2.915 E(orking en)-.11 E(vironments where Quick-Start w)-.44 E(ould)
-.11 E(potentially be useful.)100.8 527 Q(These are the en)5.5 E
(vironments that might consider an initial deplo)-.44 E(yment)-.11 E
(of Quick-Start in the routers and end-nodes, where the incenti)100.8
540 Q -.165(ve)-.275 G 2.75(sf).165 G(or routers to deplo)-2.75 E(y)-.11
E(Quick-Start might be the most clear)100.8 553 Q(.)-.605 E 2.75(*C)
100.8 579 S(entrally-administrated or)-2.75 E -.055(ga)-.198 G
(nizational Intranets: These intranets often ha).055 E .33 -.165(ve l)
-.22 H(ar).165 E(ge)-.198 E(netw)100.8 592 Q(ork capacity)-.11 E 2.75
(,w)-.715 G(ith netw)-2.75 E
(orks that are underutilized for much of the time [P)-.11 E(ABL+05].)
-1.012 E(Such Intranets might also include high-bandwidth and high-dela\
y paths to remote sites.)100.8 605 Q(In)5.5 E(such an en)100.8 618 Q
(vironment, Quick-Start w)-.44 E
(ould be of bene\214t to users, and there w)-.11 E(ould be a clear)-.11
E(incenti)100.8 631 Q .33 -.165(ve f)-.275 H(or the deplo).165 E
(yment of Quick-Start in routers.)-.11 E -.165(Fo)5.5 G 2.75(re).165 G
(xample, Quick-Start could be)-2.915 E
(quite useful in high-bandwidth netw)100.8 644 Q
(orks used for scienti\214c computing.)-.11 E 2.75(*W)100.8 670 S
(ireless netw)-3.19 E
(orks: Quick-Start could also be useful in high-delay en)-.11 E
(vironments of)-.44 E(Cellular W)100.8 683 Q(ide-Area W)-.44 E
(ireless Netw)-.44 E
(orks such as the GPRS [BW97] and their enhancements)-.11 E(and ne)100.8
696 Q(xt generations. F)-.165 E(or e)-.165 E
(xample, GPRS EDGE \(Enhanced Data for GSM Ev)-.165 E(olution\) is)-.22
E -.165(ex)100.8 709 S(pected to pro).165 E
(vide wireless bandwidth of up to 384 Kbps \(roughly 32 1500-byte pack)
-.165 E(ets)-.11 E
(per second\) while the GPRS round-trip times range typically from fe)
100.8 722 Q 2.75(wh)-.275 G(undred)-2.75 E(Flo)72 769 Q 198.525
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(10.3. [P)2.75 F(age 46])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(milliseconds to o)100.8 85 Q
-.165(ve)-.165 G 2.75(ras).165 G(econd e)-2.75 E(xcluding an)-.165 E
2.75(yp)-.165 G(ossible queueing delays in the netw)-2.75 E(ork)-.11 E
([GP)100.8 98 Q(AR02]. In addition, these netw)-1.012 E
(orks sometimes ha)-.11 E .33 -.165(ve v)-.22 H
(ariable additional delays due to)-.11 E
(resource allocation that could be a)100.8 111 Q -.22(vo)-.22 G
(ided by k).22 E(eeping the connection path constantly)-.11 E
(utilized, starting from initial slo)100.8 124 Q 2.75(w-start. Thus,)
-.275 F(Quick-Start could be of signi\214cant bene\214t to)2.75 E
(users in these en)100.8 137 Q(vironments.)-.44 E 2.75(*P)100.8 163 S
(aths o)-2.915 E -.165(ve)-.165 G 2.75(rs).165 G
(atellite links: Geostationary Orbit \(GEO\) satellite links ha)-2.75 E
.33 -.165(ve o)-.22 H(ne-w).165 E(ay)-.11 E(propag)100.8 176 Q(ation de\
lays on the order of 250 ms while the bandwidth can be measured in)-.055
E(me)100.8 189 Q -.055(ga)-.165 G(bits per second [RFC2488]. Because of\
 the considerable bandwidth-delay product on).055 E(the link, TCP')100.8
202 Q 2.75(ss)-.605 G(lo)-2.75 E
(w-start is a major performance limitation in the be)-.275 E
(ginning of the)-.165 E 2.75(connection. A)100.8 215 R(lar)2.75 E
(ge initial congestion windo)-.198 E 2.75(ww)-.275 G
(ould be useful to users of such satellite)-2.86 E(links.)100.8 228 Q
2.75(*S)100.8 254 S(ingle-hop paths: Quick-Start should w)-2.75 E
(ork well o)-.11 E -.165(ve)-.165 G 2.75(rp).165 G
(oint-to-point single-hop paths,)-2.75 E
(e.g., from a host to an adjacent serv)100.8 267 Q(er)-.165 E 5.5(.Q)
-.605 G(uick-Start w)-5.5 E(ould w)-.11 E(ork o)-.11 E -.165(ve)-.165 G
2.75(ras).165 G(ingle-hop IP path)-2.75 E
(consisting of a multi-access link only if the host w)100.8 280 Q
(as able to determine if the path to the)-.11 E(ne)100.8 293 Q
(xt IP hop has been signi\214cantly underutilized o)-.165 E -.165(ve)
-.165 G 2.75(rt).165 G(he recent past.)-2.75 E(If the multi-access)5.5 E
(link includes a layer)100.8 306 Q
(-2 switch, then the attached host cannot necessarily determine the)-.22
E(status of the other links in the layer)100.8 319 Q(-2 netw)-.22 E
(ork.)-.11 E/F1 11/Times-Bold@0 SF(10.4.)72 358 Q/F2 13/Times-Bold@0 SF
3.25(AC)5.5 G(omparison with the Deployment Pr)-3.25 E(oblems of ECN)
-.234 E F0(Gi)100.8 384 Q -.165(ve)-.275 G 2.75(nt).165 G
(he glacially slo)-2.75 E 2.75(wr)-.275 G(ate of deplo)-2.75 E
(yment of ECN in the Internet to date [MAF05], it is)-.11 E
(disconcerting to note that some of the deplo)100.8 397 Q
(yment problems of Quick-Start are e)-.11 E -.165(ve)-.275 G 2.75(ng)
.165 G(reater)-2.75 E(than those of ECN.)100.8 410 Q(First, unlik)5.5 E
2.75(eE)-.11 G(CN, which can be of bene\214t e)-2.75 E -.165(ve)-.275 G
2.75(ni).165 G 2.75(fi)-2.75 G 2.75(ti)-2.75 G 2.75(so)-2.75 G
(nly deplo)-2.75 E(yed)-.11 E
(on one of the routers along the end-to-end path, a connection')100.8
423 Q 2.75(su)-.605 G(se of Quick-Start requires)-2.75 E
(Quick-Start deplo)100.8 436 Q
(yment on all of the routers along the end-to-end path.)-.11 E
(Second, unlik)5.5 E(e)-.11 E
(ECN, which uses an allocated \214eld in the IP header)100.8 449 Q 2.75
(,Q)-.44 G(uick-Start requires the e)-2.75 E(xtra)-.165 E
(complications of an IP Option, which can be dif)100.8 462 Q
(\214cult to pass through the current Internet)-.275 E([MAF05].)100.8
475 Q(Ho)100.8 501 Q(we)-.275 E -.165(ve)-.275 G .88 -.44(r, i).165 H
2.75(ns).44 G(pite of these issues, there is some hope for the deplo)
-2.75 E(yment of Quick-Start, at)-.11 E(least in protected corners of t\
he Internet, because the potential bene\214ts of Quick-Start to)100.8
514 Q(the user are considerably more dramatic than those of ECN.)100.8
527 Q(Rather than simply replacing)5.5 E(the occasional dropped pack)
100.8 540 Q(et by an ECN-mark)-.11 E(ed pack)-.11 E
(et, Quick-Start is capable of)-.11 E(dramatically increasing the throu\
ghput of connections in underutilized en)100.8 553 Q(vironments)-.44 E
([SAF06].)100.8 566 Q F1(11.)72 605 Q/F3 14/Times-Bold@0 SF
(Security Considerations)5.5 E F0(Sections 9.4 and 9.6 discuss the secu\
rity considerations related to Quick-Start.)100.8 631 Q(Section 9.4)5.5
E(discusses the potential ab)100.8 644 Q
(use of Quick-Start by senders or recei)-.22 E -.165(ve)-.275 G
(rs lying about whether the).165 E(request w)100.8 657 Q(as appro)-.11 E
-.165(ve)-.165 G 2.75(do).165 G 2.75(ra)-2.75 G(bout the appro)-2.75 E
-.165(ve)-.165 G 2.75(dr).165 G
(ate, and of routers in collusion to misuse)-2.75 E 2.75
(Quick-Start. Section)100.8 670 R
(9.5 discusses potential problems with traf)2.75 E
(\214c normalizers that re)-.275 E(write)-.275 E(IP TTLs in pack)100.8
683 Q(et headers.)-.11 E
(All of these problems could result in the sender using a Rate)5.5 E
(Request that w)100.8 696 Q(as inappropriately lar)-.11 E
(ge, or thinking that a request w)-.198 E(as appro)-.11 E -.165(ve)-.165
G 2.75(dw).165 G(hen it w)-2.75 E(as)-.11 E(in f)100.8 709 Q
(act denied by at least one router along the path.)-.11 E
(This inappropriate use of Quick-Start)5.5 E
(could result in congestion and an unacceptable le)100.8 722 Q -.165(ve)
-.275 G 2.75(lo).165 G 2.75(fp)-2.75 G(ack)-2.75 E
(et drops along the path, Such)-.11 E(Flo)72 769 Q 206.775
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(11. [P)2.75 F(age 47])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
(congestion could also be part of a Denial of Service attack.)100.8 85 Q
(Section 9.6 discusses a potential attack on the routers' processing an\
d state load from an)100.8 111 Q(attack of Quick-Start Requests.)100.8
124 Q(Section 9.6 also discusses a potential attack on the)5.5 E -.22
(av)100.8 137 S(ailable Quick-Start bandwidth by sending bogus Quick-St\
art requests for bandwidth that)-.055 E(will not in f)100.8 150 Q
(act be used.)-.11 E
(While this impacts the global usability of Quick-Start it does not)5.5
E(endanger the netw)100.8 163 Q(ork as a whole since TCP uses standard \
congestion control if Quick-Start)-.11 E(is not a)100.8 176 Q -.275(va)
-.22 G(ilable.).275 E
(Section 4.7.2 discusses the potential problem of pack)100.8 202 Q
(ets with Quick-Start Requests)-.11 E(dropped by middlebox)100.8 215 Q
(es along the path.)-.165 E
(As discussed in Section 5, for IPv4 IPsec Authentication Header Inte)
100.8 241 Q(grity Check V)-.165 E(alue)-1.221 E(\(AH ICV\) calculation,\
 the Quick-Start option is a mutable IPv4 option, and hence)100.8 254 Q
(completely zeroed for AH ICV calculation purposes; this is also the tr\
eatment required by)100.8 267 Q(RFC 4302 for unrecognized IPv4 options.)
100.8 280 Q(The IPv6 Quick-Start option')5.5 E 2.75(sI)-.605 G(AN)-2.75
E(A-allocated)-.385 E(option type indicates that it is a mutable option\
, hence, according to RFC 4302, its option)100.8 293 Q
(data is required to be zeroed for AH ICV computation purposes.)100.8
306 Q(See RFC 4302 for further)5.5 E -.165(ex)100.8 319 S(planation.)
.165 E(Section 6.2 discusses possible problems of Quick-Start used by c\
onnections carried o)100.8 345 Q -.165(ve)-.165 G(r).165 E
(simple tunnels that are not compatible with Quick-Start.)100.8 358 Q
(In this case it is possible that a)8.25 E
(Quick-Start Request is erroneously considered appro)100.8 371 Q -.165
(ve)-.165 G 2.75(db).165 G 2.75(yt)-2.75 G
(he sender without the routers)-2.75 E(in the tunnel ha)100.8 384 Q
(ving indi)-.22 E(vidually appro)-.275 E -.165(ve)-.165 G 2.75(dt).165 G
(he request, causing a f)-2.75 E(alse positi)-.11 E -.165(ve)-.275 G(.)
.165 E 1.76 -.88(We n)100.8 410 T(ote tw).88 E 2.75(oh)-.11 G
(igh-order points here.)-2.75 E
(First, the Quick-Start Nonce goes a long w)5.5 E(ay to)-.11 E -.11(wa)
-.275 G(rds).11 E(pre)100.8 423 Q -.165(ve)-.275 G(nting lar).165 E
(ge scale cheating.)-.198 E(And, second, e)5.5 E -.165(ve)-.275 G 2.75
(ni).165 G 2.75(fah)-2.75 G(ost occasionally uses Quick-Start)-2.75 E
(when it is not appro)100.8 436 Q -.165(ve)-.165 G 2.75(db).165 G 2.75
(yt)-2.75 G(he entire netw)-2.75 E(ork path the netw)-.11 E
(ork will not collapse.)-.11 E(Quick-)5.5 E(Start does not remo)100.8
449 Q .33 -.165(ve T)-.165 H(CP').165 E 2.75(sb)-.605 G
(asic congestion control mechanisms and these will kick in)-2.75 E
(when the netw)100.8 462 Q(ork is hea)-.11 E(vily loaded, rele)-.22 E
-.055(ga)-.165 G(ting an).055 E 2.75(yQ)-.165 G(uick-Start mistak)-2.75
E 2.75(et)-.11 G 2.75(oat)-2.75 G(ransient.)-2.75 E/F1 11/Times-Bold@0
SF(12.)72 501 Q/F2 14/Times-Bold@0 SF(IAN)5.5 E 3.5(AC)-.28 G
(onsiderations)-3.5 E F0
(Quick-Start requires an IP Option and a TCP Option.)100.8 527 Q F1
(12.1.)72 566 Q/F3 13/Times-Bold@0 SF(IP Option)5.5 E F0(Quick-Start re\
quires both an IPv4 Option Number \(Section 3.1\) and an IPv6 Option)
100.8 592 Q(Number \(Section 3.2\).)100.8 605 Q(IPv4 Option Number:)
100.8 631 Q/F4 11/Courier@0 SF(Copy Class Number Value Name)100.8 663 Q
(---- ----- ------ ----- ----)100.8 676 Q 26.4(00)120.6 689 S 19.8(0T)
-26.4 G 6.6(BD1 TBD2)-19.8 F 19.8(QS -)19.8 F(Quick-Start)6.6 E F0
(IPv6 Option Number [RFC2460]:)100.8 721 Q(Flo)72 769 Q 198.525
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(12.1. [P)2.75 F(age 48])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E/F1 11/Courier@0 SF 52.8
(HEX act)100.8 85 R 6.6(chg rest)13.2 F 52.8(--- ---)100.8 98 R 6.6
(--- -----)13.2 F 52.8(TBD3 00)100.8 111 R 19.8(1T)19.8 G 39.6
(BD4 Quick-Start)-19.8 F F0 -.165(Fo)100.8 143 S 2.75(rt).165 G
(he IPv6 Option Number)-2.75 E 2.75(,t)-.44 G(he \214rst tw)-2.75 E 2.75
(ob)-.11 G(its indicate that the IPv6 node skip o)-2.75 E -.165(ve)-.165
G 2.75(rt).165 G(his)-2.75 E
(option and continue processing the header if it doesn')100.8 156 Q 2.75
(tr)-.198 G(ecognize the option type, and the)-2.75 E
(third bit indicates that the Option Data may change en-route.)100.8 169
Q(In both cases this document should be listed as the reference documen\
t.)100.8 195 Q/F2 11/Times-Bold@0 SF(12.2.)72 234 Q/F3 13/Times-Bold@0
SF(TCP Option)5.5 E F0
(Quick-Start requires a TCP Option Number \(Section 4.2\).)100.8 260 Q
(TCP Option Number:)100.8 286 Q F1(Kind Length Meaning)120.6 305 Q
(---- ------ ------------------------------)120.6 318 Q(TBD5 8)120.6 331
Q(Quick-Start Response)39.6 E F0
(This document should be listed as the reference document.)100.8 376 Q
F2(13.)72 415 Q/F4 14/Times-Bold@0 SF(Conclusions)5.5 E F0 1.76 -.88
(We a)100.8 441 T(re presenting the Quick-Start mechanism as a simple, \
understandable, and).88 E(incrementally-deplo)100.8 454 Q
(yable mechanism that w)-.11 E(ould be suf)-.11 E(\214cient to allo)
-.275 E 2.75(ws)-.275 G(ome connections to)-2.75 E(start up with lar)
100.8 467 Q(ge initial rates, or lar)-.198 E
(ge initial congestion windo)-.198 E(ws, in o)-.275 E -.165(ve)-.165 G
(rpro).165 E(visioned,)-.165 E(high-bandwidth en)100.8 480 Q 2.75
(vironments. W)-.44 F 2.75(ee)-.88 G
(xpect there will be an increasing number of)-2.915 E -.165(ove)100.8
493 S(rpro).165 E(visioned, high-bandwidth en)-.165 E
(vironments where the Quick-Start mechanism, or)-.44 E
(another mechanism of similar po)100.8 506 Q(wer)-.275 E 2.75(,c)-.44 G
(ould be of signi\214cant bene\214t to a wide range of)-2.75 E(traf)
100.8 519 Q 2.75(\214c. W)-.275 F 2.75(ea)-.88 G(re presenting the Quic\
k-Start mechanism as a request for the community to)-2.75 E(pro)100.8
532 Q(vide feedback and e)-.165 E
(xperimentation on issues relating to Quick-Start.)-.165 E F2(14.)72 571
Q F4(Ackno)5.5 E(wledgements)-.14 E F0
(The authors wish to thank Mark Handle)100.8 597 Q 2.75(yf)-.165 G
(or discussions of these issues.)-2.75 E(The authors also)5.5 E
(thank the End-to-End Research Group, the T)100.8 610 Q
(ransport Services W)-.385 E(orking Group, and)-.88 E(members of IP)
100.8 623 Q(AM')-1.012 E 2.75(sp)-.605 G(rogram on Lar)-2.75 E
(ge Scale Communication Netw)-.198 E(orks for both positi)-.11 E -.165
(ve)-.275 G(and ne)100.8 636 Q -.055(ga)-.165 G(ti).055 E .33 -.165
(ve f)-.275 H(eedback on this proposal.).165 E 1.76 -.88(We t)5.5 H
(hank Srikanth Sundarrajan for the initial).88 E
(implementation of Quick-Start in the NS simulator)100.8 649 Q 2.75(,a)
-.44 G(nd for the initial simulation study)-2.75 E(.)-.715 E(Man)100.8
662 Q 2.75(yt)-.165 G(hanks to Da)-2.75 E(vid Black and Joe T)-.22 E
(ouch for e)-.88 E(xtensi)-.165 E .33 -.165(ve f)-.275 H
(eedback on Quick-Start and IP).165 E 2.75(tunnels. W)100.8 675 R 2.75
(ea)-.88 G(lso thank Mohammed Ashraf, John Border)-2.75 E 2.75(,B)-.44 G
(ob Briscoe, Martin Duk)-2.75 E(e, T)-.11 E(om)-.88 E(Dunig)100.8 688 Q
(an, Mitchell Erblich, Gorry F)-.055 E(airhurst, John Heidemann, P)-.165
E(aul Hyder)-.165 E 2.75(,D)-.44 G(ina Katabi and)-2.75 E -1.221(Ve)
100.8 701 S(rn P)1.221 E(axson for feedback.)-.165 E
(Thanks also to Gorry F)5.5 E(airhurst for the suggestion of adding the)
-.165 E(QS Nonce to the Report of Appro)100.8 714 Q -.165(ve)-.165 G
2.75(dR).165 G(ate.)-2.75 E(Flo)72 769 Q 206.775
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(14. [P)2.75 F(age 49])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(The v)100.8 85 Q(ersion of th\
e QS Nonce in this document is based on a proposal from Guohan Lu)-.165
E 2.75([L05]. Earlier)100.8 98 R -.165(ve)2.75 G(rsions of this documen\
t contained an eight-bit QS Nonce, and subsequent).165 E -.165(ve)100.8
111 S(rsions discussed the possibility of a four).165 E(-bit QS Nonce.)
-.22 E(This draft b)100.8 137 Q(uilds upon the concepts described in [R\
FC3390], [AHO98], [RFC2415], and)-.22 E 2.75([RFC3168]. Some)100.8 150 R
(of the te)2.75 E(xt on Quick-Start in tunnels w)-.165 E(as borro)-.11 E
(wed directly from RFC)-.275 E(3168.)100.8 163 Q
(This document is the de)100.8 189 Q -.165(ve)-.275 G
(lopment of a proposal originally by Amit Jain for Initial W).165 E
(indo)-.44 E(w)-.275 E(Disco)100.8 202 Q -.165(ve)-.165 G(ry).165 E(.)
-.715 E/F1 11/Times-Bold@0 SF(A.)72 254 Q/F2 14/Times-Bold@0 SF
(Related W)5.5 E(ork)-1.05 E F0(The Quick-Start proposal, tak)100.8 280
Q(en together with HighSpeed TCP [RFC3649] or other)-.11 E(transport pr\
otocols for high-bandwidth transfers, could go a signi\214cant w)100.8
293 Q(ay to)-.11 E -.11(wa)-.275 G(rds).11 E -.165(ex)100.8 306 S
(tending the range of performance for best-ef).165 E(fort traf)-.275 E
(\214c in the Internet.)-.275 E(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88
-.44(r, t).165 H(here).44 E(are man)100.8 319 Q 2.75(yt)-.165 G
(hings that the Quick-Start proposal w)-2.75 E(ould not accomplish.)-.11
E(Quick-Start is not a)5.5 E(congestion control mechanism, and w)100.8
332 Q(ould not help in making more precise use of the)-.11 E -.22(av)
100.8 345 S(ailable bandwidth, that is, of achie)-.055 E
(ving the goal of high throughput with lo)-.275 E 2.75(wd)-.275 G
(elay and)-2.75 E(lo)100.8 358 Q 2.75(wp)-.275 G(ack)-2.75 E
(et loss rates.)-.11 E(Quick-Start w)5.5 E(ould not gi)-.11 E .33 -.165
(ve r)-.275 H(outers more control o).165 E -.165(ve)-.165 G 2.75(rt).165
G(he decrease)-2.75 E(rates of acti)100.8 371 Q .33 -.165(ve c)-.275 H
(onnections.).165 E(In addition, an)100.8 397 Q 2.75(ye)-.165 G -.275
(va)-3.025 G
(luation of Quick-Start must include a discussion of the relati).275 E
.33 -.165(ve b)-.275 H(ene\214ts).165 E(of approaches that use no e)
100.8 410 Q
(xplicit information from routers, and of approaches that use)-.165 E
(more \214ne-grained feedback from routers as part of a lar)100.8 423 Q
(ger congestion control mechanism.)-.198 E 1.76 -.88(We d)100.8 436 T
(iscuss se).88 E -.165(ve)-.275 G
(ral classes of proposals in the sections belo).165 E -.715(w.)-.275 G
F1(A.1.)72 475 Q/F3 13/Times-Bold@0 SF -.325(Fa)5.5 G
(st Start-ups without Explicit Inf).325 E(ormation fr)-.325 E
(om Routers)-.234 E F0(One possibility w)100.8 501 Q
(ould be for senders to use information from the pack)-.11 E
(et streams to learn)-.11 E(about the a)100.8 514 Q -.275(va)-.22 G
(ilable bandwidth, without e).275 E(xplicit information from routers.)
-.165 E(These techniques)5.5 E -.11(wo)100.8 527 S(uld not allo).11 E
2.75(was)-.275 G(tart-up as f)-2.75 E(ast as that a)-.11 E -.275(va)-.22
G(ilable from Quick-Start in an underutilized).275 E(en)100.8 540 Q 2.75
(vironment; one)-.44 F(has to ha)2.75 E .33 -.165(ve s)-.22 H
(ent some pack).165 E(ets already to use the pack)-.11 E
(et stream to learn)-.11 E(about a)100.8 553 Q -.275(va)-.22 G
(ilable bandwidth.).275 E(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44
(r, t).165 H(hese techniques could allo).44 E 2.75(was)-.275 G
(tart-up considerably)-2.75 E -.11(fa)100.8 566 S
(ster than the current slo).11 E 2.75(w-start. While)-.275 F
(it seems clear that approaches *without* e)2.75 E(xplicit)-.165 E
(feedback from the routers will be strictly less po)100.8 579 Q
(werful that is possible *with* e)-.275 E(xplicit)-.165 E
(feedback, it is also possible that approaches that are more aggressi)
100.8 592 Q .33 -.165(ve t)-.275 H(han slo).165 E(w-start are)-.275 E
(possible without the comple)100.8 605 Q(xity in)-.165 E -.22(vo)-.44 G
(lv).22 E(ed in obtaining e)-.165 E(xplicit feedback from routers.)-.165
E(Periodic pack)100.8 631 Q(et streams:)-.11 E([JD02] e)100.8 644 Q
(xplores the use of periodic pack)-.165 E(et streams to estimate the a)
-.11 E -.275(va)-.22 G(ilable bandwidth).275 E(along a path.)100.8 657 Q
(The idea is that the one-w)5.5 E(ay delays of a periodic pack)-.11 E
(et stream sho)-.11 E 2.75(wa)-.275 G(n)-2.75 E
(increasing trend when the stream')100.8 670 Q 2.75(sr)-.605 G
(ate is higher than the a)-2.75 E -.275(va)-.22 G
(ilable bandwidth \(due to an).275 E(increasing queue\).)100.8 683 Q
(While [JD02] states that the proposed mechanism does not cause)5.5 E
(signi\214cant increases in netw)100.8 696 Q
(ork utilization, losses, or delays when done by one \215o)-.11 E 2.75
(wa)-.275 G 2.75(ta)-2.75 G(time, the approach could be problematic if \
conducted concurrently by a number of \215o)100.8 709 Q(ws.)-.275 E
([JD02] also gi)100.8 722 Q -.165(ve)-.275 G 2.75(sa).165 G 2.75(no)
-2.75 G -.165(ve)-2.915 G(rvie).165 E 2.75(wo)-.275 G 2.75(fs)-2.75 G
(ome of the earlier w)-2.75 E(ork on inferring the a)-.11 E -.275(va)
-.22 G(ilable).275 E(Flo)72 769 Q 201.583
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.1. [P)2.75 F(age 50])
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(April 2007)2.75 E(October 2006)112.127 E(bandwidth from pack)100.8 85 Q
(et trains.)-.11 E(Swift-Start:)100.8 111 Q
(The Swift Start proposal from [PRAKS02] combines pack)100.8 124 Q
(et-pair and pack)-.11 E(et-pacing)-.11 E 2.75(techniques. An)100.8 137
R(initial congestion windo)2.75 E 2.75(wo)-.275 G 2.75(ff)-2.75 G
(our se)-2.75 E(gments is used to estimate the)-.165 E -.22(av)100.8 150
S(ailable bandwidth along the path.)-.055 E
(This estimate is then used to dramatically increase the)5.5 E
(congestion windo)100.8 163 Q 2.75(wd)-.275 G(uring the second R)-2.75 E
(TT of data transmission.)-.66 E(SP)100.8 189 Q(AND:)-1.012 E
(In the TCP/SP)100.8 202 Q
(AND proposal from [ZQK00] for speeding up short data transfers, netw)
-1.012 E(ork)-.11 E(performance information w)100.8 215 Q
(ould be shared among man)-.11 E 2.75(yc)-.165 G
(o-located hosts to estimate each)-2.75 E(connection')100.8 228 Q 2.75
(sf)-.605 G(air share of the netw)-2.86 E(ork resources.)-.11 E
(Based on such estimation and the transfer)5.5 E(size, the TCP sender w)
100.8 241 Q(ould determine the optimal initial congestion windo)-.11 E
2.75(ws)-.275 G 2.75(ize. The)-2.75 F(design for TCP/SP)100.8 254 Q
(AND uses a performance g)-1.012 E(ate)-.055 E -.11(wa)-.275 G 2.75(yt)
.11 G(hat monitors all traf)-2.75 E(\214c entering and)-.275 E(lea)100.8
267 Q(ving an or)-.22 E -.055(ga)-.198 G(nization').055 E 2.75(sn)-.605
G(etw)-2.75 E(ork.)-.11 E(Sharing information among TCP connections:)
100.8 293 Q(The Congestion Manager [RFC3124] and TCP control block shar\
ing [RFC2140] both)100.8 306 Q(propose sharing congestion information a\
mong multiple TCP connections with the same)100.8 319 Q 2.75
(endpoints. W)100.8 332 R(ith the Congestion Manager)-.44 E 2.75(,an)
-.44 G .55 -.275(ew T)-2.75 H(CP connection could start with a high).275
E(initial cwnd if it w)100.8 345 Q
(as sharing the path and the cwnd with a pre-e)-.11 E
(xisting TCP connection to)-.165 E
(the same destination that had already obtained a high congestion windo)
100.8 358 Q 4.18 -.715(w. R)-.275 H(FC 2140).715 E
(discusses ensemble sharing, where an established connection')100.8 371
Q 2.75(sc)-.605 G(ongestion windo)-2.75 E 2.75(wc)-.275 G(ould)-2.75 E
(be `di)100.8 384 Q(vided up' to be shared with a ne)-.275 E 2.75(wc)
-.275 G(onnection to the same host.)-2.75 E(Ho)5.5 E(we)-.275 E -.165
(ve)-.275 G .88 -.44(r, n).165 H(either of).44 E
(these approaches addresses the case of a connection to a ne)100.8 397 Q
2.75(wd)-.275 G(estination, with no e)-2.75 E(xisting)-.165 E(or recent\
 connection \(and therefore congestion control state\) to that destinat\
ion.)100.8 410 Q(While continued research on the limits of the ability \
of TCP and other transport protocols)100.8 436 Q(to learn of a)100.8 449
Q -.275(va)-.22 G(ilable bandwidth without e).275 E
(xplicit feedback from the router seems useful, we)-.165 E
(note that there are se)100.8 462 Q -.165(ve)-.275 G
(ral fundamental adv).165 E(antages of e)-.275 E
(xplicit feedback from routers.)-.165 E(\(1\) Explicit feedback is f)
100.8 488 Q(aster than implicit feedback:)-.11 E(One adv)100.8 501 Q
(antage of e)-.275 E(xplicit feedback from the routers is that it allo)
-.165 E(ws the transport sender to)-.275 E(reliably learn of a)100.8 514
Q -.275(va)-.22 G(ilable bandwidth in one round-trip time.).275 E
(\(2\) Explicit feedback is more reliable than implicit feedback:)100.8
540 Q -.77(Te)100.8 553 S(chniques that attempt to assess the a).77 E
-.275(va)-.22 G(ilable bandwidth at connection startup using).275 E
(implicit techniques are more error)100.8 566 Q
(-prone than techniques that in)-.22 E -.22(vo)-.44 G(lv).22 E 2.75(ee)
-.165 G -.165(ve)-3.025 G(ry element in the).165 E(netw)100.8 579 Q
(ork path.)-.11 E(While e)5.5 E(xplicit information from the netw)-.165
E(ork can be wrong, it has a much)-.11 E(better chance of being appropr\
iate than an end-host trying to *estimate* an appropriate)100.8 592 Q
(sending rate using "block box" probing techniques of the entire path.)
100.8 605 Q/F1 11/Times-Bold@0 SF(A.2.)72 644 Q/F2 13/Times-Bold@0 SF
(Optimistic Sending without Explicit Inf)5.5 E(ormation fr)-.325 E
(om Routers)-.234 E F0(Another possibility that has been suggested [S02\
] is for the sender to start with a lar)100.8 670 Q(ge)-.198 E
(initial windo)100.8 683 Q 2.75(ww)-.275 G(ithout e)-2.75 E
(xplicit permission from the routers and without bandwidth)-.165 E
(estimation techniques, and for the \214rst pack)100.8 696 Q
(et of the initial windo)-.11 E 2.75(wt)-.275 G 2.75(oc)-2.75 G
(ontain information)-2.75 E
(such as the size or sending rate of the initial windo)100.8 709 Q 4.18
-.715(w. T)-.275 H(he proposal w).715 E(ould be that)-.11 E
(congested routers w)100.8 722 Q
(ould use this information in the \214rst data pack)-.11 E
(et to drop or delay man)-.11 E(y)-.165 E(Flo)72 769 Q 201.583
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.2. [P)2.75 F(age 51])
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(April 2007)2.75 E(October 2006)112.127 E(or all of the pack)100.8 85 Q
(ets from that initial windo)-.11 E 4.18 -.715(w. I)-.275 H 2.75(nt).715
G(his w)-2.75 E(ay a \215o)-.11 E(w')-.275 E 2.75(so)-.605 G
(ptimistically-lar)-2.75 E(ge)-.198 E(initial windo)100.8 98 Q 2.75(ww)
-.275 G(ould not force the router to drop pack)-2.86 E
(ets from competing \215o)-.11 E(ws in the)-.275 E(netw)100.8 111 Q 2.75
(ork. Such)-.11 F(an approach w)2.75 E
(ould seem to require some mechanism for the sender to)-.11 E(ensure th\
at the routers along the path understood the mechanism for marking the \
\214rst)100.8 124 Q(pack)100.8 137 Q(et of a lar)-.11 E
(ge initial windo)-.198 E -.715(w.)-.275 G(Ob)100.8 163 Q
(viously there w)-.165 E
(ould be a number of questions to consider about an approach of)-.11 E
(optimistic sending.)100.8 176 Q(\(1\) Incremental deplo)100.8 202 Q
(yment:)-.11 E(One question w)100.8 215 Q
(ould be the potential complications of incremental deplo)-.11 E
(yment, where some)-.11 E
(of the routers along the path might not understand the pack)100.8 228 Q
(et information describing the)-.11 E(initial windo)100.8 241 Q -.715
(w.)-.275 G(\(2\) Congestion collapse:)100.8 267 Q
(There could also be concerns about congestion collapse if man)100.8 280
Q 2.75<798d>-.165 G -.275(ow)-2.75 G 2.75(su).275 G(sed lar)-2.75 E
(ge initial)-.198 E(windo)100.8 293 Q(ws, man)-.275 E 2.75(yp)-.165 G
(ack)-2.75 E(ets were dropped from optimistic initial windo)-.11 E
(ws, and man)-.275 E(y)-.165 E(congested links ended up carrying pack)
100.8 306 Q(ets that are only going to be dropped do)-.11 E(wnstream.)
-.275 E(\(3\) Distrib)100.8 332 Q(uted Denial of Service attacks:)-.22 E
2.75(At)100.8 345 S(hird question w)-2.75 E(ould be the potential role \
of optimistic senders in amplifying the damage)-.11 E(done by a Distrib)
100.8 358 Q(uted Denial of Service \(DDoS\) attack \(assuming attack)
-.22 E(ers use compliant)-.11 E
(congestion control in the hopes of "\215ying under the radar"\).)100.8
371 Q(\(4\) Performance hits if a pack)100.8 397 Q(et is dropped:)-.11 E
2.75(Af)100.8 410 S(ourth issue w)-2.75 E
(ould be to quantify the performance hit to the connection when a pack)
-.11 E(et is)-.11 E(dropped from one of the initial windo)100.8 423 Q
(ws.)-.275 E/F1 11/Times-Bold@0 SF(A.3.)72 462 Q/F2 13/Times-Bold@0 SF
-.325(Fa)5.5 G(st Start-ups with other Inf).325 E(ormation fr)-.325 E
(om Routers)-.234 E F0(There ha)100.8 488 Q .33 -.165(ve b)-.22 H
(een se).165 E -.165(ve)-.275 G(ral proposals some).165 E
(what similar to Quick-Start, where the transport)-.275 E
(protocol collects e)100.8 501 Q
(xplicit information from the routers along the path.)-.165 E
(An IP Option about the free b)100.8 527 Q(uf)-.22 E(fer size:)-.275 E
(In related w)100.8 540 Q(ork, [P00] in)-.11 E -.165(ve)-.44 G(stig).165
E(ates the use of a slightly dif)-.055 E(ferent IP option for TCP)-.275
E(connections to disco)100.8 553 Q -.165(ve)-.165 G 2.75(rt).165 G(he a)
-2.75 E -.275(va)-.22 G(ilable bandwidth along the path.).275 E
(In that proposal, the IP)5.5 E(option w)100.8 566 Q
(ould query the routers along the path about the smallest a)-.11 E -.275
(va)-.22 G(ilable free b).275 E(uf)-.22 E(fer size.)-.275 E
(Also, the IP option w)100.8 579 Q(ould ha)-.11 E .33 -.165(ve b)-.22 H
(een sent after the initial SYN e).165 E(xchange, when the TCP)-.165 E
(sender already had an estimate of the round-trip time.)100.8 592 Q
(The Performance T)100.8 618 Q(ransparenc)-.385 E 2.75(yP)-.165 G
(rotocol:)-2.75 E(The Performance T)100.8 631 Q(ransparenc)-.385 E 2.75
(yP)-.165 G(rotocol \(PTP\) includes a proposal for a single PTP pack)
-2.75 E(et)-.11 E(that w)100.8 644 Q(ould collect information from rout\
ers along the path from the sender to the recei)-.11 E -.165(ve)-.275 G
(r).165 E 2.75([W00]. F)100.8 657 R(or e)-.165 E
(xample, a single PTP pack)-.165 E
(et could be used to determine the bottleneck)-.11 E
(bandwidth along a path.)100.8 670 Q(ETEN:)100.8 696 Q
(Additional proposals for end nodes to collect e)100.8 709 Q
(xplicit information from routers include one)-.165 E -.275(va)100.8 722
S(riant of Explicit T).275 E
(ransport Error Noti\214cation \(ETEN\), which includes a cumulati)-.385
E -.165(ve)-.275 G(Flo)72 769 Q 201.583
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.3. [P)2.75 F(age 52])
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(April 2007)2.75 E(October 2006)112.127 E
(mechanism to notify endpoints of aggre)100.8 85 Q -.055(ga)-.165 G
(te congestion statistics along the path [KAPS02].).055 E(\(A second v)
100.8 98 Q(ariant in [KSEP)-.275 E(A04] does not depend on cumulati)
-1.012 E .33 -.165(ve c)-.275 H(ongestion statistics from).165 E
(the netw)100.8 111 Q(ork.\))-.11 E/F1 11/Times-Bold@0 SF(A.4.)72 150 Q
/F2 13/Times-Bold@0 SF -.325(Fa)5.5 G(st Start-ups with mor).325 E 3.25
(eF)-.234 G(ine-Grained F)-3.25 E(eedback fr)-.325 E(om Routers)-.234 E
F0(Proposals for more \214ne-grained congestion-related feedback from r\
outers include XCP)100.8 176 Q
([KHR02], MaxNet [MaxNet], and AntiECN marking [K03].)100.8 189 Q
(Section B.6 discusses in)5.5 E(more detail the relationship between Qu\
ick-Start and proposals for more \214ne-grained per)100.8 202 Q(-)-.22 E
(pack)100.8 215 Q(et feedback from routers.)-.11 E(XCP:)100.8 241 Q
(Proposals such as XCP for ne)100.8 254 Q 2.75(wc)-.275 G
(ongestion control mechanisms based on more feedback)-2.75 E
(from routers are more po)100.8 267 Q(werful than Quick-Start, b)-.275 E
(ut also are more comple)-.22 E 2.75(xt)-.165 G 2.75(ou)-2.75 G
(nderstand)-2.75 E(and more dif)100.8 280 Q(\214cult to deplo)-.275 E
4.18 -.715(y. X)-.11 H(CP routers maintain no per).715 E(-\215o)-.22 E
2.75(ws)-.275 G(tate, b)-2.75 E(ut pro)-.22 E(vide more)-.165 E(\214ne-\
grained feedback to end-nodes than the one-bit congestion feedback of E\
CN.)100.8 293 Q(The per)5.5 E(-)-.22 E(pack)100.8 306 Q
(et feedback from XCP can be positi)-.11 E .33 -.165(ve o)-.275 H 2.75
(rn).165 G -2.475 -.165(eg a)-2.75 H(ti).165 E -.165(ve)-.275 G 2.75(,a)
.165 G(nd speci\214es the increase or)-2.75 E(decrease in the sender')
100.8 319 Q 2.75(sc)-.605 G(ongestion windo)-2.75 E 2.75(ww)-.275 G
(hen this pack)-2.75 E(et is ackno)-.11 E 2.75(wledged. XCP)-.275 F
(is a)2.75 E(full-\215edge congestion control scheme, whereas Quick-Sta\
rt represents a quick check to)100.8 332 Q(determine if the netw)100.8
345 Q(ork path is signi\214cantly underutilized such that a connection \
can start)-.11 E -.11(fa)100.8 358 S(ster and then f).11 E
(all back to TCP')-.11 E 2.75(ss)-.605 G
(tandard congestion control algorithms.)-2.75 E(AntiECN:)100.8 384 Q
(The AntiECN proposal is for a single bit in the pack)100.8 397 Q
(et header that routers could set to)-.11 E(indicate that the)100.8 410
Q 2.75(ya)-.165 G(re underutilized.)-2.75 E -.165(Fo)5.5 G 2.75(re).165
G(ach TCP A)-2.75 E(CK arri)-.44 E(ving at the sender indicating)-.275 E
(that a pack)100.8 423 Q(et has been recei)-.11 E -.165(ve)-.275 G 2.75
(dw).165 G(ith the Anti-ECN bit set, the sender w)-2.75 E
(ould be able to)-.11 E(increase its congestion windo)100.8 436 Q 2.75
(wb)-.275 G 2.75(yo)-2.75 G(ne pack)-2.75 E(et, as it w)-.11 E
(ould during slo)-.11 E(w-start.)-.275 E F1(A.5.)72 475 Q F2 -.325(Fa)
5.5 G(st Start-ups with Lo).325 E(wer)-.13 E(-Than-Best-Eff)-.481 E
(ort Ser)-.325 E(vice)-.13 E F0(There ha)100.8 501 Q .33 -.165(ve b)-.22
H(een proposals for routers to pro).165 E(vide a Lo)-.165 E(wer Ef)-.275
E(fort dif)-.275 E(ferentiated service that)-.275 E -.11(wo)100.8 514 S
(uld be lo).11 E(wer than best ef)-.275 E(fort [RFC3662].)-.275 E
(Such a service could carry traf)5.5 E(\214c for which)-.275 E(deli)
100.8 527 Q -.165(ve)-.275 G
(ry is strictly optional, or could carry traf).165 E
(\214c that is important b)-.275 E(ut that has lo)-.22 E 2.75(wp)-.275 G
(riority)-2.75 E(in terms of time.)100.8 540 Q
(Because it does not interfere with best-ef)5.5 E(fort traf)-.275 E
(\214c, Lo)-.275 E(wer Ef)-.275 E(fort)-.275 E
(services could be used by transport protocols that start-up f)100.8 553
Q(aster than slo)-.11 E 2.75(w-start. F)-.275 F(or)-.165 E -.165(ex)
100.8 566 S
(ample, [SGF05] is a proposal for the transport sender to use lo).165 E
(w-priority traf)-.275 E(\214c for much)-.275 E(of the initial traf)
100.8 579 Q
(\214c, with routers con\214gured to use strict priority queueing.)-.275
E 2.75(As)100.8 605 S(eparate b)-2.75 E
(ut related issue is that of belo)-.22 E(w-best-ef)-.275 E(fort TCP)
-.275 E 2.75(,v)-1.221 G(ariants of TCP that w)-3.025 E(ould)-.11 E
(not rely on Lo)100.8 618 Q(wer Ef)-.275 E(fort services in the netw)
-.275 E(ork, b)-.11 E(ut w)-.22 E(ould approximate belo)-.11 E
(w-best-ef)-.275 E(fort)-.275 E(traf)100.8 631 Q(\214c by detecting and\
 responding to congestion sooner that standard TCP)-.275 E 5.5(.T)-1.221
G(CP Nice)-5.5 E([V02] and TCP Lo)100.8 644 Q 2.75(wP)-.275 G
(riority \(TCP-LP\) [KK03] are tw)-2.75 E 2.75(os)-.11 G
(uch proposals for belo)-2.75 E(w-best-)-.275 E(ef)100.8 657 Q(fort TCP)
-.275 E 2.75(,w)-1.221 G(ith the purpose of allo)-2.75 E
(wing TCP connections to use the bandwidth unused by)-.275 E
(TCP and other traf)100.8 670 Q(\214c in a non-intrusi)-.275 E .33 -.165
(ve f)-.275 H 2.75(ashion. Both).055 F(TCP Nice and TCP Lo)2.75 E 2.75
(wP)-.275 G(riority use)-2.75 E(the def)100.8 683 Q(ault slo)-.11 E
(w-start mechanisms of TCP)-.275 E(.)-1.221 E 1.76 -.88(We n)100.8 709 T
(ote that Quick-Start is quite dif).88 E(ferent from either a Lo)-.275 E
(wer Ef)-.275 E(fort service or a belo)-.275 E(w-)-.275 E(best-ef)100.8
722 Q(fort v)-.275 E(ariant of TCP)-.275 E 5.5(.U)-1.221 G(nlik)-5.5 E
2.75(et)-.11 G(hese proposals, Quick-Start is intended to be useful for)
-2.75 E(Flo)72 769 Q 201.583(yd/Allman/Jain/Sarolahti Section)-.11 F
2.75(A.5. [P)2.75 F(age 53])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(best-ef)100.8 85 Q(fort traf)
-.275 E(\214c that wishes to recei)-.275 E .33 -.165(ve a)-.275 H 2.75
(tl).165 G(east as much bandwidth as competing best-ef)-2.75 E(fort)
-.275 E(connections.)100.8 98 Q/F1 11/Times-Bold@0 SF(B.)72 137 Q/F2 14
/Times-Bold@0 SF(Design Decisions)5.5 E F1(B.1.)72 176 Q/F3 13
/Times-Bold@0 SF(Alter)5.5 E(nate Mechanisms f)-.195 E
(or the Quick-Start Request: ICMP and RSVP)-.325 E F0(This document has\
 proposed using an IP Option for the Quick-Start Request from the)100.8
202 Q(sender to the recei)100.8 215 Q -.165(ve)-.275 G .88 -.44(r, a)
.165 H(nd using transport mechanisms for the Quick-Start Response from)
.44 E(the recei)100.8 228 Q -.165(ve)-.275 G 2.75(rb).165 G
(ack to the sender)-2.75 E 5.5(.I)-.605 G 2.75(nt)-5.5 G
(his section we discuss alternate mechanisms, and)-2.75 E(consider whet\
her ICMP \([RFC792], [RFC2463]\) or RSVP [RFC2205] protocols could be)
100.8 241 Q(used for deli)100.8 254 Q -.165(ve)-.275 G
(ring the Quick-Start Request.).165 E F1 2.75(B.1.1. ICMP)72 293 R F0
(Being a control protocol used between Internet nodes, one could ar)
100.8 319 Q(gue that ICMP is the)-.198 E
(ideal method for requesting a permission for f)100.8 332 Q
(aster startup from routers.)-.11 E(The ICMP header)5.5 E(is abo)100.8
345 Q .33 -.165(ve t)-.165 H(he IP header).165 E 5.5(.Q)-.605 G
(uick-Start could be accomplished with ICMP as follo)-5.5 E(ws: If the)
-.275 E(ICMP protocol is used to implement Quick-Start, the equi)100.8
358 Q -.275(va)-.275 G(lent of the Quick-Start IP).275 E(option w)100.8
371 Q
(ould be carried in the ICMP header of the ICMP Quick-Start Request.)
-.11 E(The ICMP)5.5 E(Quick-Start Request w)100.8 384 Q(ould ha)-.11 E
.33 -.165(ve t)-.22 H 2.75(op).165 G
(ass by the routers on the path to the recei)-2.75 E -.165(ve)-.275 G
.88 -.44(r, p).165 H(ossibly).44 E
(using the IP Router Alert option [RFC2113].)100.8 397 Q 2.75(Ar)5.5 G
(outer that appro)-2.75 E -.165(ve)-.165 G 2.75(st).165 G
(he Quick-Start)-2.75 E(Request w)100.8 410 Q(ould tak)-.11 E 2.75(et)
-.11 G
(he same actions as in the case with the Quick-Start IP Option, and)
-2.75 E(forw)100.8 423 Q(ard the pack)-.11 E(et to the ne)-.11 E
(xt router along the path.)-.165 E 2.75(Ar)5.5 G
(outer that does not appro)-2.75 E .33 -.165(ve t)-.165 H(he).165 E
(Quick-Start Request, e)100.8 436 Q -.165(ve)-.275 G 2.75(nw).165 G
(ith a decreased v)-2.75 E(alue for the Requested Rate, w)-.275 E
(ould delete the)-.11 E(ICMP Quick-Start Request, and send an ICMP Repl\
y to the sender that the request w)100.8 449 Q(as not)-.11 E(appro)100.8
462 Q -.165(ve)-.165 G 2.75(d. If).165 F(the ICMP Reply w)2.75 E
(as dropped in the netw)-.11 E(ork, and did not reach the recei)-.11 E
-.165(ve)-.275 G -.44(r,).165 G(the sender w)100.8 475 Q(ould still kno)
-.11 E 2.75(wt)-.275 G(hat the request w)-2.75 E(as not appro)-.11 E
-.165(ve)-.165 G 2.75(df).165 G(rom the absence of)-2.75 E
(feedback from the recei)100.8 488 Q -.165(ve)-.275 G 3.96 -.605(r. I)
.165 H 2.75(ft).605 G(he ICMP Quick-Start request w)-2.75 E
(as dropped in the netw)-.11 E(ork)-.11 E
(due to congestion, the sender w)100.8 501 Q
(ould assume that the request w)-.11 E(as not appro)-.11 E -.165(ve)
-.165 G 2.75(d. The).165 F(ICMP)2.75 E(message w)100.8 514 Q
(ould need the source and destination port numbers for demultiple)-.11 E
(xing at the end)-.165 E 2.75(nodes. If)100.8 527 R
(the ICMP Quick-Start Request reached the recei)2.75 E -.165(ve)-.275 G
.88 -.44(r, t).165 H(he recei).44 E -.165(ve)-.275 G 2.75(rw).165 G
(ould use)-2.86 E(transport-le)100.8 540 Q -.165(ve)-.275 G 2.75(lo).165
G 2.75(ra)-2.75 G(pplication-le)-2.75 E -.165(ve)-.275 G 2.75(lm).165 G
(echanisms to send a response to the sender)-2.75 E 2.75(,e)-.44 G
(xactly as)-2.915 E(with the IP Option.)100.8 553 Q
(One bene\214t of using ICMP w)100.8 579 Q(ould be that the deli)-.11 E
-.165(ve)-.275 G(ry of the TCP SYN pack).165 E(et or other)-.11 E
(initial pack)100.8 592 Q(et w)-.11 E
(ould not be delayed by IP option processing at routers.)-.11 E 2.75(Ag)
5.5 G(reater adv)-2.75 E(antage)-.275 E(is that if middlebox)100.8 605 Q
(es were blocking pack)-.165 E
(ets with Quick-Start Requests, using the Quick-)-.11 E
(Start Request in a separate ICMP pack)100.8 618 Q(et w)-.11 E
(ould mean that the middlebox beha)-.11 E(vior w)-.22 E(ould)-.11 E
(not af)100.8 631 Q(fect the connection as a whole.)-.275 E(\(T)5.5 E
2.75(og)-.88 G(et this rob)-2.75 E(ustness to middlebox)-.22 E
(es with TCP)-.165 E(using an IP Quick-Start Option, one w)100.8 644 Q
(ould ha)-.11 E .33 -.165(ve t)-.22 H 2.75(oh).165 G -2.475 -.22(av e)
-2.75 H 2.75(aT)2.97 G(CP-le)-2.75 E -.165(ve)-.275 G 2.75(lQ).165 G
(uick-Start Request)-2.75 E(pack)100.8 657 Q
(et that could be sent concurrently b)-.11 E
(ut separately from the TCP SYN pack)-.22 E(et.\))-.11 E(Ho)100.8 683 Q
(we)-.275 E -.165(ve)-.275 G .88 -.44(r, t).165 H
(here are a number of disadv).44 E(antages to using ICMP)-.275 E 5.5(.S)
-1.221 G(ome \214re)-5.5 E -.11(wa)-.275 G(lls and).11 E(middlebox)100.8
696 Q(es may not forw)-.165 E(ard the ICMP Quick-Start Request pack)-.11
E 2.75(ets. \(If)-.11 F(an ICMP Reply)2.75 E(pack)100.8 709 Q
(et from a router to the sender is dropped in the netw)-.11 E
(ork, the sender w)-.11 E(ould still kno)-.11 E(w)-.275 E
(that the request w)100.8 722 Q(as not appro)-.11 E -.165(ve)-.165 G
(d, as stated earlier).165 E 2.75(,s)-.44 G 2.75(ot)-2.75 G(his w)-2.75
E(ould not be as serious of a)-.11 E(Flo)72 769 Q 193.938
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(B.1.1. [P)2.75 F(age 54])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E 2.75(problem.\) In)100.8 85 R
(addition, it w)2.75 E(ould be dif)-.11 E
(\214cult, if not impossible, for a router in the middle of)-.275 E
(an IP tunnel to deli)100.8 98 Q -.165(ve)-.275 G 2.75(ra).165 G 2.75
(nI)-2.75 G(CMP Reply pack)-2.75 E(et to the actual source, for e)-.11 E
(xample when the)-.165 E
(inner IP header is encrypted as in IPsec ESP tunnel mode [RFC4301].)
100.8 111 Q(Ag)5.5 E(ain, ho)-.055 E(we)-.275 E -.165(ve)-.275 G .88
-.44(r, t).165 H(he).44 E(ICMP Reply pack)100.8 124 Q(et w)-.11 E
(ould not be essential to the correct operation of ICMP Quick-Start.)
-.11 E(Unauthenticated out-of-band ICMP messages could enable some type\
s of attacks by third-)100.8 150 Q(party malicious hosts that are not p\
ossible when the control information is carried in-band)100.8 163 Q
(with the IP pack)100.8 176 Q(ets that can only be altered by the route\
rs on the connection path. Finally)-.11 E(,)-.715 E
(as a minor concern, using ICMP w)100.8 189 Q
(ould cause a small amount of additional traf)-.11 E(\214c in the)-.275
E(netw)100.8 202 Q(ork, which is not the case when using IP options.)
-.11 E/F1 11/Times-Bold@0 SF 2.75(B.1.2. RSVP)72 241 R F0 -.44(Wi)100.8
267 S(th some modi\214cations RSVP [RFC2205] could be used as a bearer \
protocol for carrying).44 E
(the Quick-Start Requests. Because routers are e)100.8 280 Q
(xpected to process RSVP pack)-.165 E(ets more)-.11 E -.165(ex)100.8 293
S(tensi).165 E -.165(ve)-.275 G
(ly than the normal transport protocol IP pack).165 E(ets, deli)-.11 E
-.165(ve)-.275 G(ring a Quick-Start rate).165 E
(request using an RSVP pack)100.8 306 Q(et w)-.11 E
(ould seem an appealing choice. Ho)-.11 E(we)-.275 E -.165(ve)-.275 G
.88 -.44(r, Q).165 H(uick-Start with).44 E(RSVP w)100.8 319 Q
(ould require a fe)-.11 E 2.75(wd)-.275 G(if)-2.75 E
(ferences from the con)-.275 E -.165(ve)-.44 G(ntional usage of RSVP)
.165 E 2.75(.Q)-1.221 G(uick-Start)-2.75 E -.11(wo)100.8 332 S(uld not \
require periodical refreshing of soft state, because Quick-Start does n\
ot require).11 E(per)100.8 345 Q(-connection state in routers.)-.22 E
(Quick-Start Requests w)5.5 E(ould be transmitted do)-.11 E(wnstream)
-.275 E(from the sender to recei)100.8 358 Q -.165(ve)-.275 G 2.75(ri)
.165 G 2.75(nt)-2.75 G(he RSVP P)-2.75 E(ath messages, which is dif)
-.165 E(ferent from the)-.275 E(con)100.8 371 Q -.165(ve)-.44 G
(ntional RSVP model where the reserv).165 E
(ations originate from the recei)-.275 E -.165(ve)-.275 G 1.21 -.605
(r. F).165 H(urthermore,).605 E(the Quick-Start Response w)100.8 384 Q
(ould be sent using the transport-le)-.11 E -.165(ve)-.275 G 2.75(lo)
.165 G 2.75(ra)-2.75 G(pplication-le)-2.75 E -.165(ve)-.275 G(l).165 E
(mechanisms instead of using the RSVP Resv message.)100.8 397 Q
(If RSVP w)100.8 423 Q(as used for carrying a Quick-Start Request, a ne)
-.11 E 2.75(w")-.275 G(Quick-Start Request" class)-2.75 E(object w)100.8
436 Q(ould be included in the RSVP P)-.11 E
(ath message that is sent from the sender to)-.165 E(recei)100.8 449 Q
-.165(ve)-.275 G 1.21 -.605(r. T).165 H(he object w).605 E
(ould contain the rate request \214eld in addition to the common length)
-.11 E(and type \214elds. The Send_TTL \214eld in the RSVP common heade\
r could be used as the)100.8 462 Q(equi)100.8 475 Q -.275(va)-.275 G
(lent of the QS TTL \214eld.).275 E
(The Quick-Start capable routers along the path w)5.5 E(ould)-.11 E
(inspect the Quick-Start Request object in the RSVP P)100.8 488 Q
(ath message, decrement Send_TTL)-.165 E(and adjust the rate request \
\214eld if needed. If an RSVP router did not understand the Quick-)100.8
501 Q(Start Request object, it w)100.8 514 Q
(ould reject the entire RSVP message and send an RSVP P)-.11 E(athErr)
-.165 E(message back to the sender)100.8 527 Q 5.5(.W)-.605 G
(hen an RSVP message with the Quick-Start Request object)-5.5 E
(reaches the recei)100.8 540 Q -.165(ve)-.275 G .88 -.44(r, t).165 H
(he recei).44 E -.165(ve)-.275 G 2.75(rs).165 G
(ends a Quick-Start Reply message in the corresponding)-2.75 E
(transport protocol header in the same w)100.8 553 Q
(ay as described in the conte)-.11 E(xt of IP options earlier)-.165 E(.)
-.605 E(If the RSVP message with the Quick-Start Request object w)100.8
566 Q(as dropped along the path, the)-.11 E(transport sender w)100.8 579
Q(ould simply proceed with the normal congestion control procedures.)
-.11 E(Much of the discussion about bene\214ts and dra)100.8 605 Q
(wbacks of using ICMP for making the)-.165 E(Quick-Start Request also a\
pplies to the RSVP case. If the Quick-Start Request w)100.8 618 Q(as)
-.11 E(transmitted in a separate pack)100.8 631 Q
(et instead of as an IP option, the transport protocol pack)-.11 E(et)
-.11 E(deli)100.8 644 Q -.165(ve)-.275 G(ry w).165 E(ould not be delaye\
d due to IP option processing at the routers, and the initial)-.11 E
(transport pack)100.8 657 Q(ets w)-.11 E
(ould reach their destination more reliably)-.11 E 2.75(.T)-.715 G
(he possible disadv)-2.75 E(antages)-.275 E
(of using ICMP and RSVP are also e)100.8 670 Q
(xpected to be similar: middlebox)-.165 E(es in the netw)-.165 E
(ork may)-.11 E(not be able to forw)100.8 683 Q
(ard the Quick-Start Request messages, and the IP tunnels might cause)
-.11 E(problems for processing the Quick-Start Requests.)100.8 696 Q
(Flo)72 769 Q 193.938(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(B.1.2. [P)2.75 F(age 55])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E/F1 11/Times-Bold@0 SF(B.2.)72
85 Q/F2 13/Times-Bold@0 SF(Alter)5.5 E(nate Encoding Functions)-.195 E
F0(In this section we look at alternate encoding functions for the Rate\
 Request \214eld in the)100.8 111 Q(Quick-Start Request.)100.8 124 Q
(The main requirements for this function is that it should ha)5.5 E .33
-.165(ve a)-.22 H(suf)100.8 137 Q
(\214ciently wide range for the requested rate.)-.275 E
(There is no need for o)5.5 E -.165(ve)-.165 G(rly-\214ne-grained).165 E
(precision in the requested rate.)100.8 150 Q(Similarly)5.5 E 2.75(,w)
-.715 G(hile it w)-2.75 E(ould be attracti)-.11 E .33 -.165(ve f)-.275 H
(or the encoding).165 E(function to be easily computable, it is also po\
ssible for end-nodes and routers to simply)100.8 163 Q
(store the table gi)100.8 176 Q(ving the mapping between the v)-.275 E
(alue N in the Rate Request \214eld, and the)-.275 E
(actual rate request f\(N\).)100.8 189 Q
(In this section we consider possible encoding methods for Rate)5.5 E
(Request \214elds of dif)100.8 202 Q(ferent sizes, including four)-.275
E(-bit, eight-bit, and lar)-.22 E(ger Rate Request)-.198 E(\214elds.)
100.8 215 Q(Linear functions:)100.8 241 Q(One possible proposal w)100.8
254 Q(ould be for the Rate Request \214eld to be formatted in bits per)
-.11 E(second, scaled so that one unit equals M Kbps, for some \214x)
100.8 267 Q(ed v)-.165 E(alue of M.)-.275 E(Thus, for the)5.5 E -.275
(va)100.8 280 S(lue N in the Rate Request \214eld, the requested rate w)
.275 E(ould be M*N Kbps.)-.11 E(Po)100.8 306 Q(wers of tw)-.275 E(o:)
-.11 E(If a granularity of f)100.8 319 Q(actors of tw)-.11 E 2.75(oi)
-.11 G 2.75(ss)-2.75 G(uf)-2.75 E
(\214cient for the Rate Request, then the encoding)-.275 E
(function with the most range w)100.8 332 Q
(ould be for the requested rate to be K*2^N, for N the v)-.11 E(alue)
-.275 E(in the Rate Request \214eld, and for K some constant.)100.8 345
Q -.165(Fo)5.5 G 2.75(rN).165 G(=0, the rate request w)-2.75 E
(ould be set)-.11 E(to zero, re)100.8 358 Q -.055(ga)-.165 G
(rdless of the encoding function.).055 E -.165(Fo)5.5 G 2.75(re).165 G
(xample, for K=40,000 and an eight-bit)-2.915 E
(Rate Request \214eld, the request range w)100.8 371 Q
(ould be from 80 Kbps to 40*2^255 Kbps.)-.11 E(This)5.5 E(clearly w)
100.8 384 Q(ould be an unnecessarily lar)-.11 E(ge request range.)-.198
E -.165(Fo)100.8 410 S 2.75(raf).165 G(our)-2.75 E(-bit Rate Request \
\214eld, the upper limit on the rate request is 1.3 Gbps.)-.22 E
(It seems)5.5 E(to us that an upper limit of 1.3 Gbps w)100.8 423 Q
(ould be \214ne for the Quick-Start rate request, and that)-.11 E(conne\
ctions wishing to start up with a higher initial sending rate should be\
 encouraged to)100.8 436 Q(use other mechanisms, such as the e)100.8 449
Q(xplicit reserv)-.165 E(ation of bandwidth.)-.275 E
(If an upper limit of)5.5 E(1.3 Gbps w)100.8 462 Q
(as not acceptable, then \214v)-.11 E 2.75(eo)-.165 G 2.75(rs)-2.75 G
(ix bits could be used for the Rate Request \214eld.)-2.75 E(The lo)
100.8 488 Q(wer limit of 80 Kbps could be useful for \215o)-.275 E
(ws with round-trip times of a second or)-.275 E 2.75(more. F)100.8 501
R(or a \215o)-.165 E 2.75(ww)-.275 G
(ith a round-trip time of one second, as is typical in some wireless)
-2.75 E(netw)100.8 514 Q(orks, the TCP initial windo)-.11 E 2.75(wo)
-.275 G 2.75(f4)-2.75 G(380 bytes allo)-2.75 E(wed by [RFC3390] \(gi)
-.275 E -.165(ve)-.275 G 2.75(na).165 G(ppropriate)-2.75 E(pack)100.8
527 Q(et sizes\) w)-.11 E
(ould translate to an initial sending rate of 35 Kbps.)-.11 E
(Thus, for TCP \215o)5.5 E(ws, a)-.275 E
(rate request of 80 Kbps could be useful for some \215o)100.8 540 Q
(ws with lar)-.275 E(ge round-trip times.)-.198 E(The lo)100.8 566 Q
(wer limit of 80 Kbps could also be useful for some non-TCP \215o)-.275
E(ws that send small)-.275 E(pack)100.8 579 Q
(ets, with at most one small pack)-.11 E(et e)-.11 E -.165(ve)-.275 G
(ry 10 ms.).165 E 2.75(Ar)5.5 G(ate request of 80 Kbps w)-2.75 E(ould)
-.11 E(translate to a rate of a hundred 100-byte pack)100.8 592 Q
(ets per second \(including pack)-.11 E(et headers\).)-.11 E
(While some small-pack)100.8 605 Q(et \215o)-.11 E(ws with lar)-.275 E
(ge round-trip times might \214nd a smaller rate)-.198 E
(request of 40 Kbps to be useful, our assumption is that a lo)100.8 618
Q(wer limit of 80 Kbps on the rate)-.275 E
(request will be generally suf)100.8 631 Q 2.75(\214cient. Ag)-.275 F
(ain, if the lo)-.055 E(wer limit of 80 kbps w)-.275 E(as not)-.11 E
(acceptable, then e)100.8 644 Q
(xtra bits could be used for the Rate Request \214eld.)-.165 E
(If the granularity of f)100.8 670 Q(actors of tw)-.11 E 2.75(ow)-.11 G
(as too coarse, then the encoding function could use a)-2.86 E
(base less than tw)100.8 683 Q 2.75(o. An)-.11 F
(alternate form for the encoding function w)2.75 E(ould be to use a h)
-.11 E(ybrid)-.055 E(of linear and e)100.8 696 Q(xponential functions.)
-.165 E 2.75(Am)100.8 722 S(antissa and e)-2.75 E
(xponent representation:)-.165 E(Flo)72 769 Q 202.188
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(B.2. [P)2.75 F(age 56])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
(Section 4.4 of [B05] suggests a mantissa and e)100.8 85 Q
(xponent representation for the Quick-Start)-.165 E(encoding function.)
100.8 98 Q -.44(Wi)5.5 G(th e and f as the binary numbers in the e).44 E
(xponent and mantissa \214elds,)-.165 E(and with 0 <= f < 1, this w)
100.8 111 Q(ould represent the rate \(1+f\)*2^e.)-.11 E
([B05] suggests a mantissa)5.5 E
(\214eld for f of 8, 16, or 24 bits, with an e)100.8 124 Q
(xponent \214eld for e of 8 bits.)-.165 E(This representation)5.5 E -.11
(wo)100.8 137 S(uld allo).11 E 2.75(wl)-.275 G(ar)-2.75 E
(ger rate requests, with an encoding that is less coarse than the po)
-.198 E(wers-of-)-.275 E(tw)100.8 150 Q 2.75(oe)-.11 G
(ncoding used in this document.)-2.75 E
(Constraints of the transport protocol:)100.8 176 Q 1.76 -.88(We n)100.8
189 T(ote that the Rate Request is also constrained by the abilities of\
 the transport protocol.).88 E -.165(Fo)100.8 202 S 2.75(re).165 G
(xample, for TCP with W)-2.915 E(indo)-.44 E 2.75(wS)-.275 G
(caling, the maximum windo)-2.75 E 2.75(wi)-.275 G 2.75(sa)-2.75 G 2.75
(tm)-2.75 G(ost 2**30 bytes.)-2.75 E -.165(Fo)100.8 215 S 2.75(raT).165
G(CP connection with a long, 1 second round-trip time, this w)-2.75 E
(ould gi)-.11 E .33 -.165(ve a m)-.275 H(aximum).165 E
(sending rate of 1.07 Gbps.)100.8 228 Q/F1 11/Times-Bold@0 SF(B.3.)72
267 Q/F2 13/Times-Bold@0 SF(The Quick-Start Request: P)5.5 E(ack)-.13 E
(ets or Bytes?)-.13 E F0(One of the design questions is whether the Rat\
e Request \214eld should be in bytes per second)100.8 293 Q(or in pack)
100.8 306 Q(ets per second.)-.11 E 1.76 -.88(We d)5.5 H
(iscuss this separately from the perspecti).88 E .33 -.165(ve o)-.275 H
2.75(ft).165 G(he transport,)-2.75 E(and from the perspecti)100.8 319 Q
.33 -.165(ve o)-.275 H 2.75(ft).165 G(he router)-2.75 E(.)-.605 E -.165
(Fo)100.8 345 S 2.75(rT).165 G(CP)-2.75 E 2.75(,t)-1.221 G(he results f\
rom the Quick-Start Request are translated into a congestion windo)-2.75
E(w)-.275 E(in bytes, using the measured round-trip time and the MSS.)
100.8 358 Q(This windo)5.5 E 2.75(wa)-.275 G(pplies only to)-2.75 E(the\
 bytes of data payload, and does not include the bytes in the TCP or IP\
 pack)100.8 371 Q(et headers.)-.11 E(Other transport protocols w)100.8
384 Q(ould concei)-.11 E -.275(va)-.275 G
(bly use the Quick-Start Request directly in).275 E(pack)100.8 397 Q(et\
s per second, or could translate the Quick-Start Request to a congestio\
n windo)-.11 E 2.75(wi)-.275 G(n)-2.75 E(pack)100.8 410 Q(ets.)-.11 E
(The assumption of this draft is that the router only appro)100.8 436 Q
-.165(ve)-.165 G 2.75(st).165 G(he Quick-Start Request when)-2.75 E
(the output link is signi\214cantly underutilized.)100.8 449 Q -.165(Fo)
5.5 G 2.75(rt).165 G(his, the router could measure the)-2.75 E -.22(av)
100.8 462 S(ailable bandwidth in bytes per second, or could con)-.055 E
-.165(ve)-.44 G(rt between pack).165 E(ets and bytes by)-.11 E
(some mechanism.)100.8 475 Q(If the Quick-Start Request w)100.8 501 Q
(as in bytes per second, and applied only to the data payload,)-.11 E
(then the router w)100.8 514 Q(ould ha)-.11 E .33 -.165(ve t)-.22 H 2.75
(oc).165 G(on)-2.75 E -.165(ve)-.44 G
(rt from bytes per second of data payload, to bytes per).165 E
(second of pack)100.8 527 Q(ets on the wire.)-.11 E
(If the Rate Request \214eld w)5.5 E(as in bytes per second and the)-.11
E(sender ended up using v)100.8 540 Q(ery small pack)-.165 E
(ets, this could translate to a signi\214cantly lar)-.11 E(ger)-.198 E
(number in terms of bytes per second on the wire.)100.8 553 Q
(Therefore, for a Quick-Start Request in)5.5 E(bytes per second, it mak)
100.8 566 Q
(es most sense for this to include the transport and IP headers as)-.11
E(well as the data payload.)100.8 579 Q
(Of course, this will be at best a rough approximation on the part)5.5 E
(of the sender; the transport-le)100.8 592 Q -.165(ve)-.275 G 2.75(ls)
.165 G(ender might not kno)-2.75 E 2.75(wt)-.275 G
(he size of the transport and IP)-2.75 E
(headers in bytes, and might kno)100.8 605 Q 2.75(wn)-.275 G
(othing at all about the separate headers added in IP)-2.75 E
(tunnels do)100.8 618 Q 2.75(wnstream. This)-.275 F
(rough estimate seems suf)2.75 E(\214cient, ho)-.275 E(we)-.275 E -.165
(ve)-.275 G .88 -.44(r, g).165 H -2.365 -.275(iv e).44 H 2.75(nt).275 G
(he o)-2.75 E -.165(ve)-.165 G(rall lack).165 E
(of \214ne precision in Quick-Start functionality)100.8 631 Q(.)-.715 E
(It has been suggested that the router could possibly use information f\
rom the MSS option)100.8 657 Q(in the TCP pack)100.8 670 Q
(et header of the SYN pack)-.11 E(et to con)-.11 E -.165(ve)-.44 G
(rt the Quick-Start Request from).165 E(pack)100.8 683 Q
(ets per second to bytes per second, or vice v)-.11 E 2.75(ersa. This)
-.165 F -.11(wo)2.75 G(uld be problematic for).11 E(se)100.8 696 Q -.165
(ve)-.275 G(ral reasons.).165 E
(First, if IPsec is used, the TCP header will be encrypted.)5.5 E
(Second, the)5.5 E
(MSS option is de\214ned as the maximum MSS that the TCP sender e)100.8
709 Q(xpects to recei)-.165 E -.165(ve)-.275 G 2.75(,n).165 G(ot)-2.75 E
(the maximum MSS that the TCP sender plans to send [RFC793].)100.8 722 Q
(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44(r, i).165 H 2.75(ti).44 G
2.75(sp)-2.75 G(robably)-2.75 E(Flo)72 769 Q 202.188
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(B.3. [P)2.75 F(age 57])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(often the case that this MSS \
also applies as an upper bound on the MSS used by the TCP)100.8 85 Q
(sender in sending.)100.8 98 Q 1.76 -.88(We n)100.8 124 T
(ote that the sender does not necessarily kno).88 E 2.75(wt)-.275 G
(he P)-2.75 E(ath MTU when the Quick-Start)-.165 E
(Request is sent, or when the initial windo)100.8 137 Q 2.75(wo)-.275 G
2.75(fd)-2.75 G(ata is sent.)-2.75 E(Thus, with IPv4, pack)5.5 E
(ets from)-.11 E(the initial windo)100.8 150 Q 2.75(wc)-.275 G
(ould end up being fragmented in the netw)-2.75 E(ork if the "Don')-.11
E 2.75(tF)-.198 G(ragment")-2.75 E(\(DF\) bit is not set [RFC1191].)
100.8 163 Q 2.75(AR)5.5 G
(ate Request in bytes per second is reasonably rob)-2.75 E(ust to)-.22 E
2.75(fragmentation. Clearly)100.8 176 R 2.75(aR)2.75 G
(ate Request in pack)-2.75 E(ets per second is less rob)-.11 E
(ust in the presence)-.22 E(of fragmentation.)100.8 189 Q
(Interactions between lar)5.5 E(ger initial windo)-.198 E(ws and P)-.275
E(ath MTU Disco)-.165 E -.165(ve)-.165 G(ry).165 E
(are discussed in more detail in RFC 3390 [RFC3390].)100.8 202 Q -.165
(Fo)100.8 228 S 2.75(raQ).165 G
(uick-Start Request in bytes per second, the transport senders w)-2.75 E
(ould ha)-.11 E .33 -.165(ve t)-.22 H(he).165 E(additional complication\
 of estimating the bandwidth usage added by the pack)100.8 241 Q
(et headers.)-.11 E 1.76 -.88(We h)100.8 267 T -2.475 -.22(av e).88 H
(chosen a Rate Request \214eld in bytes per second rather than in pack)
2.97 E(ets per second)-.11 E(because it seems some)100.8 280 Q
(what more rob)-.275 E(ust, particularly to routers.)-.22 E/F1 11
/Times-Bold@0 SF(B.4.)72 319 Q/F2 13/Times-Bold@0 SF
(Quick-Start Semantics: T)5.5 E(otal Rate or Additional Rate?)-1.196 E
F0 -.165(Fo)100.8 345 S 2.75(raQ).165 G
(uick-Start Request sent in the middle of a connection, there are tw)
-2.75 E 2.75(op)-.11 G(ossible)-2.75 E
(semantics for the Rate Request \214eld, as follo)100.8 358 Q(ws:)-.275
E(\(1\) T)100.8 384 Q(otal Rate: The requested Rate Request is the requ\
ested total rate for the connection,)-.88 E
(including the current rate; or)100.8 397 Q(\(2\) Additional Rate: The \
requested Rate Request is the requested increase in the total rate)100.8
423 Q(for that connection, o)100.8 436 Q -.165(ve)-.165 G 2.75(ra).165 G
(nd abo)-2.75 E .33 -.165(ve t)-.165 H(he current sending rate.).165 E(\
When the Quick-Start Request is sent after an idle period, the current \
sending rate is zero,)100.8 462 Q(and there is no dif)100.8 475 Q
(ference between \(1\) and \(2\) abo)-.275 E -.165(ve)-.165 G 5.5(.H)
.165 G -.275(ow)-5.5 G -2.365 -.275(ev e).275 H .88 -.44(r, a Q).275 H
(uick-Start Request can).44 E(also be sent in the middle of a connectio\
n that has not been idle, e.g., after a mobility e)100.8 488 Q -.165(ve)
-.275 G(nt,).165 E(or after an application-limited period when the send\
er is suddenly ready to send at a much)100.8 501 Q(higher rate.)100.8
514 Q(In this case, there can be a signi\214cant dif)5.5 E
(ference between \(1\) and \(2\) abo)-.275 E -.165(ve)-.165 G 5.5(.I)
.165 G(n)-5.5 E(this section we consider brie\215y the tradeof)100.8 527
Q(fs between these tw)-.275 E 2.75(oo)-.11 G(ptions, and e)-2.75 E
(xplain wh)-.165 E(y)-.055 E(we ha)100.8 540 Q .33 -.165(ve c)-.22 H
(hosen the `T).165 E(otal Rate' semantics.)-.88 E(The T)100.8 566 Q
(otal Rate semantics mak)-.88 E(es it easier for routers to `)-.11 E
(`allocate')-.814 E 2.75('t)-.814 G(he same rate to all)-2.75 E 2.75
(connections. This)100.8 579 R(lends itself to f)2.75 E
(airness, and impro)-.11 E -.165(ve)-.165 G 2.75(sc).165 G(on)-2.75 E
-.165(ve)-.44 G -.198(rg).165 G(ence times between old and).198 E(ne)
100.8 592 Q 2.75(wc)-.275 G 2.75(onnections. W)-2.75 F
(ith the Additional Rate semantics, the router w)-.44 E
(ould not necessarily)-.11 E(kno)100.8 605 Q 2.75(wt)-.275 G
(he current sending rates of the \215o)-2.75 E
(ws requesting additional rates, and therefore w)-.275 E(ould)-.11 E
(not ha)100.8 618 Q .33 -.165(ve s)-.22 H(uf).165 E
(\214cient information to use f)-.275 E
(airness as a metric in granting rate requests.)-.11 E -.44(Wi)5.5 G(th)
.44 E(the T)100.8 631 Q(otal Rate semantics, the f)-.88 E
(airness is automatic; the router is not granting rate requests)-.11 E
(for *additional* bandwidth without kno)100.8 644 Q
(wing the current sending rates of the dif)-.275 E(ferent)-.275 E<8d6f>
100.8 657 Q(ws.)-.275 E
(The Additional Rate semantics also lends itself to g)100.8 683 Q
(aming by the connection, with senders)-.055 E
(sending frequent Quick-Start Requests in the hope of g)100.8 696 Q
(aining a higher rate.)-.055 E(If the router is)5.5 E(granting the same\
 maximum rate for all rate requests, then there is little bene\214t to \
a)100.8 709 Q(connection of sending a rate request o)100.8 722 Q -.165
(ve)-.165 G 2.75(ra).165 G(nd o)-2.75 E -.165(ve)-.165 G 2.75(ra).165 G
-.055(ga)-2.75 G 2.75(in. Ho).055 F(we)-.275 E -.165(ve)-.275 G .88 -.44
(r, i).165 H 2.75(ft).44 G(he router is granting)-2.75 E(Flo)72 769 Q
202.188(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(B.4. [P)2.75 F
(age 58])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
(an *additional* rate with each rate request, o)100.8 85 Q -.165(ve)
-.165 G 2.75(ra).165 G(nd abo)-2.75 E .33 -.165(ve t)-.165 H
(he current sending rate, then it).165 E(is in a connection')100.8 98 Q
2.75(si)-.605 G(nterest to send as man)-2.75 E 2.75(yr)-.165 G
(ate requests as possible, e)-2.75 E -.165(ve)-.275 G 2.75(ni).165 G
2.75(fv)-2.75 G(ery fe)-2.915 E 2.75(wo)-.275 G(f)-2.75 E(them are in f)
100.8 111 Q(act granted.)-.11 E(Appendix E discusses a Report of Curren\
t Sending Rate as one possible function in the)100.8 137 Q
(Quick-Start Option.)100.8 150 Q(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 standardized this possible use at this time.)2.97 E/F1 11
/Times-Bold@0 SF(B.5.)72 202 Q/F2 13/Times-Bold@0 SF(Alter)5.5 E
(nate Responses to the Loss of a Quick-Start P)-.195 E(ack)-.13 E(et)
-.13 E F0(Section 4.6 discusses TCP')100.8 228 Q 2.75(sr)-.605 G
(esponse to the loss of a Quick-Start pack)-2.75 E(et in the initial)
-.11 E(windo)100.8 241 Q 4.18 -.715(w. T)-.275 H
(his section discusses se).715 E -.165(ve)-.275 G
(ral alternate responses.).165 E(One possible alternati)100.8 267 Q .33
-.165(ve t)-.275 H 2.75(or).165 G -2.365 -.275(ev e)-2.75 H
(rting to the def).275 E(ault slo)-.11 E
(w-start after the loss of a Quick-Start)-.275 E(pack)100.8 280 Q
(et from the initial windo)-.11 E 2.75(ww)-.275 G(ould ha)-2.86 E .33
-.165(ve b)-.22 H(een to halv).165 E 2.75(et)-.165 G
(he congestion windo)-2.75 E 2.75(wa)-.275 G(nd)-2.75 E
(continue in congestion a)100.8 293 Q -.22(vo)-.22 G 2.75(idance. Ho).22
F(we)-.275 E -.165(ve)-.275 G .88 -.44(r, w).165 H 2.75(en).44 G
(ote that this w)-2.75 E(ould not ha)-.11 E .33 -.165(ve b)-.22 H(een a)
.165 E(desirable response for either the connection or for the netw)
100.8 306 Q(ork as a whole.)-.11 E(The pack)5.5 E(et loss)-.11 E
(in the initial windo)100.8 319 Q 2.75(wi)-.275 G
(ndicates that Quick-Start f)-2.75 E
(ailed in \214nding an appropriate congestion)-.11 E(windo)100.8 332 Q
1.43 -.715(w, m)-.275 H(eaning that the congestion windo).715 E 2.75(wa)
-.275 G(fter halving may easily also be wrong.)-2.75 E 2.75(Am)100.8 358
S(ore moderate alternate w)-2.75 E(ould be to continue in congestion a)
-.11 E -.22(vo)-.22 G(idance from a windo).22 E 2.75(wo)-.275 G(f)-2.75
E(\(W)100.8 371 Q(-D\)/2, where W is the Quick-Start congestion windo)
-.715 E 1.43 -.715(w, a)-.275 H(nd D is the number of pack).715 E(ets)
-.11 E(dropped or mark)100.8 384 Q(ed from that windo)-.11 E 4.18 -.715
(w. H)-.275 H -.275(ow).715 G -2.365 -.275(ev e).275 H .88 -.44(r, s)
.275 H(uch an approach w).44 E(ould implicitly)-.11 E
(assume that the number of Quick-Start pack)100.8 397 Q(ets deli)-.11 E
-.165(ve)-.275 G(red is a good indication of the).165 E(appropriate a)
100.8 410 Q -.275(va)-.22 G(ilable bandwidth for that \215o).275 E 1.43
-.715(w, e)-.275 H -.165(ve).44 G 2.75(nt).165 G(hough other pack)-2.75
E(ets from that windo)-.11 E(w)-.275 E(were dropped in the netw)100.8
423 Q 2.75(ork. And,)-.11 F(further)2.75 E 2.75(,t)-.44 G
(hat using half the number of se)-2.75 E(gments that)-.165 E
(were successfully transmitted is conserv)100.8 436 Q(ati)-.275 E .33
-.165(ve e)-.275 H(nough to account for the possibly inaccurate).165 E
(congestion windo)100.8 449 Q 2.75(wi)-.275 G 2.75(ndication. W)-2.75 F
2.75(eb)-.88 G(elie)-2.75 E .33 -.165(ve t)-.275 H
(hat such an assumption w).165 E(ould require more)-.11 E
(analysis at this point, particularly in a netw)100.8 462 Q
(ork with a range of pack)-.11 E(et dropping)-.11 E
(mechanisms at the router)100.8 475 Q 2.75(,a)-.44 G
(nd we cannot recommend it at this time.)-2.75 E(Another dra)100.8 501 Q
(wback of approaches that don')-.165 E 2.75(tr)-.198 G -2.365 -.275
(ev e)-2.75 H(rt back to slo).275 E(w-start when a Quick-Start)-.275 E
(pack)100.8 514 Q(et in the initial windo)-.11 E 2.75(wi)-.275 G 2.75
(sd)-2.75 G(ropped is that such approaches could gi)-2.75 E .33 -.165
(ve t)-.275 H(he TCP recei).165 E -.165(ve)-.275 G(r).165 E 2.75(ag)
100.8 527 S(reater incenti)-2.75 E .33 -.165(ve t)-.275 H 2.75(ol).165 G
(ie about the Quick-Start request.)-2.75 E(If the sender re)5.5 E -.165
(ve)-.275 G(rts to slo).165 E(w-start)-.275 E(when a Quick-Start pack)
100.8 540 Q(et in the initial windo)-.11 E 2.75(wi)-.275 G 2.75(sd)-2.75
G(ropped, this diminishes the bene\214t a)-2.75 E(recei)100.8 553 Q
-.165(ve)-.275 G 2.75(rw).165 G(ould get from a Quick-Start request tha\
t resulted in a dropped or ECN-mark)-2.86 E(ed)-.11 E(pack)100.8 566 Q
(et.)-.11 E F1(B.6.)72 605 Q F2(Wh)5.5 E 3.25(yN)-.195 G(ot Include Mor)
-3.25 E 3.25(eF)-.234 G(unctionality?)-3.25 E F0(This proposal for Quic\
k-Start is a rather coarse-grained mechanism that w)100.8 631 Q
(ould allo)-.11 E 2.75(wa)-.275 G
(connection to use a higher sending rate along underutilized paths, b)
100.8 644 Q(ut that does not attempt)-.22 E(to pro)100.8 657 Q
(vide a ne)-.165 E(xt-generation transport protocol or congestion contr\
ol mechanism, and does)-.165 E(not attempt the goal of pro)100.8 670 Q
(viding v)-.165 E(ery high throughput with v)-.165 E(ery lo)-.165 E 2.75
(wd)-.275 G(elay)-2.75 E 5.5(.A)-.715 G 2.75(sS)-5.5 G(ection)-2.75 E
(A.4 discusses, there are a number of proposals such as XCP)100.8 683 Q
2.75(,M)-1.221 G(axNet, and AntiECN for)-2.75 E(more \214ne-grained per)
100.8 696 Q(-pack)-.22 E
(et feedback from routers than the current congestion control)-.11 E
(mechanisms, that do attempt these more ambitious goals.)100.8 709 Q
(Flo)72 769 Q 202.188(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(B.6. [P)2.75 F(age 59])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
(Compared to proposals such as XCP and AntiECN, Quick-Start of)100.8 85
Q(fers much less control.)-.275 E(Quick-Start does not attempt to pro)
100.8 98 Q(vide a ne)-.165 E 2.75(wc)-.275 G
(ongestion control mechanism, b)-2.75 E(ut simply)-.22 E(to get permiss\
ion from routers for a higher sending rate at start-up, or after an idl\
e period.)100.8 111 Q(Quick-Start can be thought of as an "anti-congest\
ion-control" mechanism, that is only of)100.8 124 Q(an)100.8 137 Q 2.75
(yu)-.165 G
(se when all of the routers along the path are signi\214cantly under)
-2.75 E 2.75(-utilized. Thus,)-.22 F(Quick-Start is of no use to)100.8
150 Q -.11(wa)-.275 G(rds a tar).11 E
(get of high link utilization, or f)-.198 E(airness in a high-)-.11 E(u\
tilization scenario, or controlling queueing delay during high-utilizat\
ion, or an)100.8 163 Q(ything of)-.165 E(the lik)100.8 176 Q(e.)-.11 E
(At the same time, Quick-Start w)100.8 202 Q(ould allo)-.11 E 2.75(wl)
-.275 G(ar)-2.75 E(ger initial windo)-.198 E(ws than w)-.275 E
(ould proposals)-.11 E
(such as AntiECN, requires less input to routers than XCP \(e.g., XCP')
100.8 215 Q 2.75(sc)-.605 G(wnd and R)-2.75 E(TT)-.66 E
(\214elds\), and w)100.8 228 Q
(ould require less frequent feedback from routers than an)-.11 E 2.75
(yn)-.165 G .55 -.275(ew c)-2.75 H(ongestion).275 E(control mechanism.)
100.8 241 Q(Thus, Quick-Start is signi\214cantly less po)5.5 E
(werful than proposals for ne)-.275 E(w)-.275 E
(congestion control mechanisms such as XCP and AntiECN, b)100.8 254 Q
(ut as po)-.22 E(werful or more)-.275 E(po)100.8 267 Q
(werful in terms of the speci\214c issue of allo)-.275 E(wing lar)-.275
E(ger initial windo)-.198 E(ws, and \(we think\))-.275 E
(more amenable to incremental deplo)100.8 280 Q
(yment in the current Internet.)-.11 E 1.76 -.88(We d)100.8 306 T 2.75
(on).88 G(ot discuss proposals such as XCP in detail, b)-2.75 E
(ut simply note that there are a number)-.22 E(of open questions.)100.8
319 Q(One question concerns whether there is a pressing need for more)
5.5 E(sophisticated congestion control mechanisms such as XCP in the In\
ternet.)100.8 332 Q(Quick-Start is)5.5 E
(inherently a rather crude tool that does not deli)100.8 345 Q -.165(ve)
-.275 G 2.75(ra).165 G(ssurances about maintaining high link)-2.75 E
(utilization and lo)100.8 358 Q 2.75(wq)-.275 G(ueueing delay;)-2.75 E
(Quick-Start is designed for use in en)5.5 E(vironments that)-.44 E(are\
 signi\214cantly underutilized, and addresses the single question of wh\
ether a higher)100.8 371 Q(sending rate is allo)100.8 384 Q 2.75
(wed. Ne)-.275 F 2.75(wc)-.275 G
(ongestion control mechanisms with more \214ne-grained)-2.75 E
(feedback from routers could allo)100.8 397 Q 2.75(wf)-.275 G
(aster startups e)-2.86 E -.165(ve)-.275 G 2.75(ni).165 G 2.75(ne)-2.75
G -.44(nv)-2.75 G(ironments with rather high).44 E(link utilization.)
100.8 410 Q(Is this a pressing requirement?)5.5 E
(Are the other bene\214ts of more \214ne-grained)5.5 E
(congestion control feedback from routers a pressing requirement?)100.8
423 Q 1.76 -.88(We w)100.8 449 T(ould ar).77 E(gue that e)-.198 E -.165
(ve)-.275 G 2.75(ni).165 G 2.75(fm)-2.75 G(ore \214ne-grained per)-2.75
E(-pack)-.22 E(et feedback from routers w)-.11 E(as)-.11 E
(implemented, it is reasonable to ha)100.8 462 Q .33 -.165(ve a s)-.22 H
(eparate mechanism such as Quick-Start for).165 E(indicating an allo)
100.8 475 Q(wed initial sending rate, or an allo)-.275 E
(wed total sending rate after an idle or)-.275 E(underutilized period.)
100.8 488 Q(One dif)100.8 514 Q(ference between Quick-Start and current\
 proposals for \214ne-grained per)-.275 E(-pack)-.22 E(et)-.11 E
(feedback such as XCP is that XCP is designed to gi)100.8 527 Q .33
-.165(ve r)-.275 H(ob).165 E(ust performance e)-.22 E -.165(ve)-.275 G
2.75(ni).165 G 2.75(nt)-2.75 G(he case)-2.75 E(where dif)100.8 540 Q
(ferent pack)-.275 E(ets within a connection routinely follo)-.11 E 2.75
(wd)-.275 G(if)-2.75 E(ferent paths.)-.275 E(XCP achie)5.5 E -.165(ve)
-.275 G(s).165 E(relati)100.8 553 Q -.165(ve)-.275 G(ly rob).165 E
(ust performance in the presence of multipath routing by using per)-.22
E(-pack)-.22 E(et)-.11 E
(feedback, where the feedback carried in a single pack)100.8 566 Q
(et is about the relati)-.11 E .33 -.165(ve i)-.275 H(ncrease or).165 E
(decrease in the rate or windo)100.8 579 Q 2.75(wt)-.275 G 2.75(ot)-2.75
G(ak)-2.75 E 2.75(ee)-.11 G -.275(ff)-2.75 G
(ect when that particular pack).275 E(et is ackno)-.11 E(wledged,)-.275
E(not about the allo)100.8 592 Q
(wed sending rate for the connection as a whole.)-.275 E(In contrast, Q\
uick-Start sends a single Quick-Start request, and the answer to that r\
equest)100.8 618 Q(gi)100.8 631 Q -.165(ve)-.275 G 2.75(st).165 G
(he allo)-2.75 E(wed sending rate for an entire windo)-.275 E 2.75(wo)
-.275 G 2.75(fd)-2.75 G 2.75(ata. As)-2.75 F 2.75(ar)2.75 G
(esult, Quick-Start could)-2.75 E(be problematic in an en)100.8 644 Q
(vironment where some fraction of the pack)-.44 E(ets in a windo)-.11 E
2.75(wo)-.275 G 2.75(fd)-2.75 G(ata)-2.75 E(tak)100.8 657 Q 2.75(ep)-.11
G(ath A, and the rest of the pack)-2.75 E(ets tak)-.11 E 2.75(ep)-.11 G
(ath B; for e)-2.75 E(xample, the Quick-Start Request)-.165 E(could ha)
100.8 670 Q .33 -.165(ve t)-.22 H(ra).165 E -.165(ve)-.22 G
(lled on path A, while half of the Quick-Start pack).165 E
(ets sent in the succeeding)-.11 E
(round-trip time are routed on path B.)100.8 683 Q 1.76 -.88(We n)5.5 H
(ote that [ZDPS01] sho).88 E(ws Internet paths to be)-.275 E
(stable on the order of R)100.8 696 Q(TTs.)-.66 E(There are also dif)
100.8 722 Q
(ferences between Quick-Start and some of the proposals for per)-.275 E
(-pack)-.22 E(et)-.11 E(Flo)72 769 Q 202.188
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(B.6. [P)2.75 F(age 60])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(feedback in terms of the numb\
er of bits of feedback required from the routers to the end-)100.8 85 Q
2.75(nodes. Quick-Start)100.8 98 R
(uses four bits of feedback in the rate request \214eld to indicate the)
2.75 E(allo)100.8 111 Q(wed sending rate.)-.275 E
(XCP allocates a byte for per)5.5 E(-pack)-.22 E
(et feedback, though there has been)-.11 E(discussion of v)100.8 124 Q
(ariants of XCP with less per)-.275 E(-pack)-.22 E(et feedback.)-.11 E
(This w)5.5 E(ould be more lik)-.11 E(e)-.11 E(other proposals such as \
anti-ECN that use a single bit of feedback from routers to indicate)
100.8 137 Q(that the sender can increase as f)100.8 150 Q(ast as slo)
-.11 E(w-starting, in response to this particular pack)-.275 E(et)-.11 E
(ackno)100.8 163 Q 2.75(wledgement. In)-.275 F
(general, there is probably considerable po)2.75 E
(wer in \214ne-grained)-.275 E(proposals with only tw)100.8 176 Q 2.75
(ob)-.11 G(its of feedback, indicating that the sender should decrease,)
-2.75 E(maintain, or increase the sending rate or windo)100.8 189 Q 2.75
(ww)-.275 G(hen this pack)-2.75 E(et is ackno)-.11 E(wledged.)-.275 E
(Ho)100.8 202 Q(we)-.275 E -.165(ve)-.275 G .88 -.44(r, t).165 H(he po)
.44 E(wer of Quick-Start w)-.275 E(ould be considerably limited if it w)
-.11 E(as restricted to)-.11 E(only tw)100.8 215 Q 2.75(ob)-.11 G
(its of feedback; it seems lik)-2.75 E
(ely that determining the initial sending rate)-.11 E(fundamentally req\
uires more bits of feedback from routers than does the steady-state, pe\
r)100.8 228 Q(-)-.22 E(pack)100.8 241 Q
(et feedback to increase or decrease the sending rate.)-.11 E
(On a more practical le)100.8 267 Q -.165(ve)-.275 G(l, one dif).165 E
(ference between Quick-Start and proposals for per)-.275 E(-pack)-.22 E
(et)-.11 E(feedback is that there are fe)100.8 280 Q
(wer open issues with Quick-Start than there w)-.275 E(ould be with a)
-.11 E(ne)100.8 293 Q 2.75(wc)-.275 G(ongestion control mechanism.)-2.75
E(Because Quick-Start is a mechanism for requesting an)5.5 E
(initial sending rate in an underutilized en)100.8 306 Q
(vironment, its f)-.44 E(airness issues are less se)-.11 E -.165(ve)
-.275 G(re than).165 E(those of a general congestion control mechanism.)
100.8 319 Q -.44(Wi)5.5 G(th Quick-Start, there is no need for).44 E(th\
e end nodes to tell the routers the round-trip time and congestion wind\
o)100.8 332 Q 1.43 -.715(w, a)-.275 H 2.75(si).715 G 2.75(sd)-2.75 G
(one in)-2.75 E(XCP; all that is needed is for the end nodes to report \
the requested sending rate.)100.8 345 Q -.88(Ta)100.8 371 S(ble 3 pro)
.88 E(vides a summary of the dif)-.165 E
(ferences between Quick-Start and proposals for per)-.275 E(-)-.22 E
(pack)100.8 384 Q(et congestion control feedback.)-.11 E(Flo)72 769 Q
202.188(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(B.6. [P)2.75 F
(age 61])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E/F1 11/Courier@0 SF
(Proposals for)391.2 85 Q 66(Quick-Start Per-Packet)246 98 R(Feedback)
6.6 E
(+------------------+----------------------+----------------------+)
100.8 111 Q 46.2(Semantics: |)107.4 124 R
(Allowed sending rate | Change in rate/window,)6.6 E 13.2(|p)226.2 137 S
(er connection.)-13.2 E 13.2(|p)33 G(er-packet.)-13.2 E
(+------------------+----------------------+----------------------+)
100.8 150 Q(Relationship to)107.4 163 Q 6.6(|I)19.8 G 6.6(na)-6.6 G 52.8
(ddition. |)-6.6 F(Replacement.)6.6 E(congestion ctrl:)107.4 176 Q 145.2
(||)13.2 G
(+------------------+----------------------+----------------------+)
100.8 189 Q 46.2(Frequency: |)107.4 202 R(Start-up, or after)6.6 E 6.6
(|E)19.8 G(very packet.)-6.6 E 13.2(|a)226.2 215 S 6.6(ni)-13.2 G
(dle period.)-6.6 E(|)33 E
(+------------------+----------------------+----------------------+)
100.8 228 Q 33(Limitations: |)107.4 241 R(Only useful on)6.6 E 6.6(|G)
46.2 G(eneral congestion)-6.6 E 13.2(|u)226.2 254 S
(nderutilized paths.|)-13.2 E(control mechanism.)13.2 E
(+------------------+----------------------+----------------------+)
100.8 267 Q(Input to routers: | Rate request.)107.4 280 Q
(|RTT, cwnd, request \(XCP\))52.8 E 145.2(||)226.2 293 S
(None \(Anti-ECN\).)-138.6 E
(+------------------+----------------------+----------------------+)
100.8 306 Q(Bits of feedback: | Four bits for)107.4 319 Q 6.6(|Af)52.8 G
(ew bits would)-6.6 E 19.8(|r)226.2 332 S(ate request.)-19.8 E 13.2(|s)
39.6 G(uffice?)-13.2 E
(+------------------+----------------------+----------------------+)
100.8 345 Q(Table 3: Differences between Quick-Start and Proposals for)
114 371 Q(Fine-Grained Per-Packet Feedback.)127.2 384 Q F0 2.75(As)100.8
416 S(eparate question concerns whether mechanisms such as Quick-Start,\
 in combination)-2.75 E
(with HighSpeed TCP and other changes in progress, w)100.8 429 Q
(ould mak)-.11 E 2.75(eas)-.11 G(igni\214cant contrib)-2.75 E(ution)-.22
E(to)100.8 442 Q -.11(wa)-.275 G(rds meeting some of these needs for ne)
.11 E 2.75(wc)-.275 G(ongestion control mechanisms.)-2.75 E(This could)
5.5 E(be vie)100.8 455 Q(wed as a positi)-.275 E .33 -.165(ve s)-.275 H
(tep to).165 E -.11(wa)-.275 G
(rds meeting some of the more pressing current needs with).11 E 2.75(as)
100.8 468 S(imple and reasonably deplo)-2.75 E
(yable mechanism, or alternately)-.11 E 2.75(,a)-.715 G 2.75(san)-2.75 G
-2.475 -.165(eg a)-2.75 H(ti).165 E .33 -.165(ve s)-.275 H(tep of).165 E
(unnecessarily delaying more fundamental changes.)100.8 481 Q -.44(Wi)
5.5 G(thout answering this question, we).44 E -.11(wo)100.8 494 S
(uld note that our o).11 E(wn approach tends to f)-.275 E -.22(avo)-.11
G 2.75(rt).22 G(he incremental deplo)-2.75 E(yment of relati)-.11 E
-.165(ve)-.275 G(ly).165 E(simple mechanisms, as long as the simple mec\
hanisms are not short-term hacks b)100.8 507 Q(ut)-.22 E
(mechanisms that lead the o)100.8 520 Q -.165(ve)-.165 G
(rall architecture in the fundamentally correct direction.).165 E/F2 11
/Times-Bold@0 SF(B.7.)72 559 Q/F3 13/Times-Bold@0 SF(Alter)5.5 E
(nate Implementations f)-.195 E(or a Quick-Start Nonce)-.325 E F2 2.75
(B.7.1. An)72 598 R(Alter)2.75 E(nate Pr)-.165 E(oposal f)-.198 E
(or the Quick-Start Nonce)-.275 E F0
(An alternate proposal for the Quick-Start Nonce from [B05] w)100.8 624
Q(ould be for an n-bit \214eld for)-.11 E(the QS Nonce, with the sender\
 generating a random nonce when it generates a Quick-Start)100.8 637 Q
2.75(Request. Each)100.8 650 R
(router that reduces the Rate Request by r w)2.75 E
(ould hash the QS nonce r times,)-.11 E(using a one-w)100.8 663 Q
(ay hash function such as MD5 [RFC1321] or the secure hash 1 [SHA1].)
-.11 E(The)5.5 E(recei)100.8 676 Q -.165(ve)-.275 G 2.75(rr).165 G
(eturns the QS nonce to the sender)-2.75 E 2.75(.B)-.605 G
(ecause the sender kno)-2.75 E(ws the original v)-.275 E(alue)-.275 E
(for the nonce, and the original rate request, the sender kno)100.8 689
Q(ws the total number of steps s)-.275 E
(that the rate has been reduced.)100.8 702 Q
(The sender then hashes the original nonce s times, to check)5.5 E
(whether the result is the same as the nonce returned by the recei)100.8
715 Q -.165(ve)-.275 G -.605(r.).165 G(Flo)72 769 Q 193.938
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(B.7.1. [P)2.75 F(age 62])
-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E
(This alternate proposal for the nonce w)100.8 85 Q
(ould be considerably more po)-.11 E(werful than the QS)-.275 E
(nonce described in Section 3.4, b)100.8 98 Q(ut it w)-.22 E
(ould also require more CPU c)-.11 E(ycles from the routers)-.165 E
(when the)100.8 111 Q 2.75(yr)-.165 G
(educe a Quick-Start request, and from the sender in v)-2.75 E
(erifying the nonce)-.165 E(returned by the recei)100.8 124 Q -.165(ve)
-.275 G 3.96 -.605(r. A).165 H 2.75(sr).605 G
(eported in [B05], routers could protect themselv)-2.75 E(es from)-.165
E(processor e)100.8 137 Q
(xhaustion attacks by limiting the rate at which the)-.165 E 2.75(yw)
-.165 G(ill appro)-2.75 E .33 -.165(ve r)-.165 H(eductions of).165 E
(Quick-Start requests.)100.8 150 Q
(Both the Function \214eld and the Reserv)100.8 176 Q
(ed \214eld in the Quick-Start Option w)-.165 E(ould allo)-.11 E 2.75
(wt)-.275 G(he)-2.75 E -.165(ex)100.8 189 S(tension of Quick-Start to u\
se Quick-Start requests with the alternate proposal for the).165 E
(Quick-Start Nonce, if it w)100.8 202 Q(as e)-.11 E -.165(ve)-.275 G
2.75(rd).165 G(esired.)-2.75 E/F1 11/Times-Bold@0 SF 2.75(B.7.2. The)72
241 R(Earlier Request-A)2.75 E(ppr)-.275 E -.11(ove)-.198 G 2.75(dQ).11
G(uick-Start Nonce)-2.75 E F0(An earlier v)100.8 267 Q
(ersion of this document included a Request-Appro)-.165 E -.165(ve)-.165
G 2.75(dQ).165 G(uick-Start Nonce \(QS)-2.75 E(Nonce\) that w)100.8 280
Q(as initialized by the sender to a non-zero, `random' eight-bit number)
-.11 E 2.75(,a)-.44 G(long)-2.75 E(with a QS TTL that w)100.8 293 Q
(as initialized to the same v)-.11 E(alue as the TTL in the IP header)
-.275 E 5.5(.T)-.605 G(he)-5.5 E(Request-Appro)100.8 306 Q -.165(ve)
-.165 G 2.75(dQ).165 G(uick-Start Nonce w)-2.75 E(ould ha)-.11 E .33
-.165(ve b)-.22 H(een returned by the transport recei).165 E -.165(ve)
-.275 G(r).165 E(to the transport sender in the Quick-Start Response.)
100.8 319 Q 2.75(Ar)5.5 G(outer could den)-2.75 E 2.75(yt)-.165 G
(he Quick-Start)-2.75 E(request by f)100.8 332 Q(ailing to decrement th\
e QS TTL \214eld, by zeroing the QS Nonce \214eld, or by)-.11 E
(deleting the Quick-Start Request from the pack)100.8 345 Q(et header)
-.11 E 5.5(.T)-.605 G(he QS Nonce w)-5.5 E(as included to)-.11 E(pro)
100.8 358 Q(vide some protection ag)-.165 E(ainst brok)-.055 E(en do)
-.11 E(wnstream routers, or ag)-.275 E(ainst misbeha)-.055 E(ving TCP)
-.22 E(recei)100.8 371 Q -.165(ve)-.275 G
(rs that might be inclined to lie about whether the Rate Request w).165
E(as appro)-.11 E -.165(ve)-.165 G 2.75(d. This).165 F(protection is no)
100.8 384 Q 2.75(wp)-.275 G(ro)-2.75 E
(vided by the QS Nonce, by the use of a random initial v)-.165 E
(alue for the)-.275 E(QS TTL \214eld, and by Quick-Start-capable router\
s hopefully either deleting the Quick-Start)100.8 397 Q
(Option or zeroing the QS TTL and QS Nonce \214elds when the)100.8 410 Q
2.75(yd)-.165 G(en)-2.75 E 2.75(yar)-.165 G(equest.)-2.75 E -.44(Wi)
100.8 436 S(th the old Request-Appro).44 E -.165(ve)-.165 G 2.75(dQ).165
G(uick-Start Nonce, along with the QS TTL \214eld set to the)-2.75 E
(same v)100.8 449 Q(alue as the TTL \214eld in the IP header)-.275 E
2.75(,t)-.44 G(he Quick-Start Request mechanism w)-2.75 E(ould)-.11 E
(ha)100.8 462 Q .33 -.165(ve b)-.22 H
(een self-terminating; the Quick-Start Request w).165 E
(ould terminate at the \214rst)-.11 E(participating router after a non-\
participating router had been encountered on the path.)100.8 475 Q(This)
5.5 E(minimizes unnecessary o)100.8 488 Q -.165(ve)-.165 G
(rhead incurred by routers because of option processing for the).165 E
(Quick-Start Request.)100.8 501 Q
(In the current speci\214cation, this "self-terminating" property is)5.5
E(pro)100.8 514 Q(vided by Quick-Start-capable routers hopefully either\
 deleting the Quick-Start Option)-.165 E
(or zeroing the Rate Request \214eld when the)100.8 527 Q 2.75(yd)-.165
G(en)-2.75 E 2.75(yar)-.165 G 2.75(equest. Because)-2.75 F(the current)
2.75 E(speci\214cation uses a random initial v)100.8 540 Q
(alue for the QS TTL, Quick-Start-capable routers can')-.275 E(t)-.198 E
(tell if the Quick-Start Request is in)100.8 553 Q -.275(va)-.44 G
(lid because of non-Quick-Start-capable routers).275 E 2.75
(upstream. This)100.8 566 R(is the cost of using a design that mak)2.75
E(es it dif)-.11 E(\214cult for the recei)-.275 E -.165(ve)-.275 G 2.75
(rt).165 G 2.75(oc)-2.75 G(heat)-2.75 E(about the v)100.8 579 Q
(alue of the QS TTL.)-.275 E F1(C.)72 618 Q/F2 14/Times-Bold@0 SF
(Quick-Start with DCCP)5.5 E F0(DCCP is a ne)100.8 644 Q 2.75(wt)-.275 G
(ransport protocol for congestion-controlled, unreliable datagrams,)
-2.75 E
(intended for applications such as streaming media, Internet telephon)
100.8 657 Q 1.43 -.715(y, a)-.165 H(nd on-line g).715 E(ames.)-.055 E
(In DCCP)100.8 670 Q 2.75(,t)-1.221 G
(he application has a choice of congestion control mechanisms, with the)
-2.75 E(currently-speci\214ed Congestion Control Identi\214ers \(CCIDs\
\) being CCID 2 for TCP-lik)100.8 683 Q(e)-.11 E(congestion control, an\
d CCID 3 for TFRC, an equation-based form of congestion control.)100.8
696 Q 1.76 -.88(We r)100.8 709 T
(efer the reader to [RFC4340] for a more detailed description of DCCP)
.88 E 2.75(,a)-1.221 G(nd of the)-2.75 E(congestion control mechanisms.)
100.8 722 Q(Flo)72 769 Q 210.438(yd/Allman/Jain/Sarolahti Section)-.11 F
2.75(C. [P)2.75 F(age 63])-.165 E 0 Cg EP
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(April 2007)2.75 E(October 2006)112.127 E(Because CCID 3 uses a rate-ba\
sed congestion control mechanism, it raises some ne)100.8 85 Q(w)-.275 E
(issues about the use of Quick-Start with transport protocols.)100.8 98
Q(In this document we don')5.5 E(t)-.198 E
(attempt to specify the use of Quick-Start with DCCP)100.8 111 Q 5.5(.H)
-1.221 G -.275(ow)-5.5 G -2.365 -.275(ev e).275 H .88 -.44(r, w).275 H
2.75(ed).44 G 2.75(od)-2.75 G(iscuss some of the)-2.75 E
(issues that might arise.)100.8 124 Q(In considering the use of Quick-S\
tart with CCID 3 for requesting a higher initial sending)100.8 150 Q
(rate, the follo)100.8 163 Q(wing questions arise:)-.275 E(\(1\) Ho)
100.8 189 Q 2.75(wd)-.275 G
(oes the sender respond if a Quick-Start pack)-2.75 E(et is dropped?)
-.11 E(As in TCP)100.8 202 Q 2.75(,i)-1.221 G 2.75(fa)-2.75 G 2.75(ni)
-2.75 G(nitial Quick-Start pack)-2.75 E
(et is dropped, the CCID 3 sender should re)-.11 E -.165(ve)-.275 G
(rt to).165 E(the congestion control mechanisms it w)100.8 215 Q
(ould ha)-.11 E .33 -.165(ve u)-.22 H
(sed if the Quick-Start request had not).165 E(been appro)100.8 228 Q
-.165(ve)-.165 G(d.).165 E(\(2\) When does the sender decide there has \
been no feedback from the recei)100.8 254 Q -.165(ve)-.275 G(r?).165 E
(Unlik)100.8 267 Q 2.75(eT)-.11 G(CP)-2.75 E 2.75(,C)-1.221 G
(CID 3 does not use ackno)-2.75 E(wledgements for e)-.275 E -.165(ve)
-.275 G(ry pack).165 E(et, or for e)-.11 E -.165(ve)-.275 G(ry other)
.165 E(pack)100.8 280 Q 2.75(et. In)-.11 F(contrast, the CCID 3 recei)
2.75 E -.165(ve)-.275 G 2.75(rs).165 G
(ends feedback to the sender roughly once per)-2.75 E(round-trip time.)
100.8 293 Q(In CCID 3, the allo)5.5 E(wed sending rate is halv)-.275 E
(ed if no feedback is recei)-.165 E -.165(ve)-.275 G(d).165 E
(from the recei)100.8 306 Q -.165(ve)-.275 G 2.75(ri).165 G 2.75(na)
-2.75 G 2.75(tl)-2.75 G
(east four round-trip times \(when the sender is sending at least one)
-2.75 E(pack)100.8 319 Q(et e)-.11 E -.165(ve)-.275 G(ry tw).165 E 2.75
(or)-.11 G(ound-trip times\).)-2.75 E
(When a Quick-Start request is used, it w)5.5 E(ould seem)-.11 E
(necessary to use a smaller time interv)100.8 332 Q
(al, e.g., to reduce the sending rate if no feedback)-.275 E(arri)100.8
345 Q -.165(ve)-.275 G 2.75(sf).165 G(rom the recei)-2.75 E -.165(ve)
-.275 G 2.75(ri).165 G 2.75(na)-2.75 G 2.75(tl)-2.75 G(east tw)-2.75 E
2.75(or)-.11 G(ound-trip times.)-2.75 E(The question also arises of ho)
100.8 371 Q 2.75(wt)-.275 G
(he sending rate should be reduced after a period of no)-2.75 E
(feedback from the recei)100.8 384 Q -.165(ve)-.275 G 3.96 -.605(r. A)
.165 H 2.75(sw).605 G(ith TCP)-2.75 E 2.75(,t)-1.221 G(he def)-2.75 E
(ault CCID 3 response of halving the)-.11 E
(sending rate is not necessarily a suf)100.8 397 Q
(\214cient response to the absence of feedback; an)-.275 E(alternati)
100.8 410 Q .33 -.165(ve i)-.275 H 2.75(st).165 G 2.75(or)-2.75 G
(educe the sending rate to the sending rate that w)-2.75 E(ould ha)-.11
E .33 -.165(ve b)-.22 H(een used if no).165 E
(Quick-Start request had been appro)100.8 423 Q -.165(ve)-.165 G 2.75
(d. That).165 F(is, if a CCID 3 sender uses a Quick-Start)2.75 E
(request, special rules might be required to handle the sender')100.8
436 Q 2.75(sr)-.605 G(esponse to a period of no)-2.75 E
(feedback from the recei)100.8 449 Q -.165(ve)-.275 G 2.75(rr).165 G
-2.475 -.165(eg a)-2.75 H(rding the Quick-Start pack).165 E(ets.)-.11 E
(Similarly)100.8 475 Q 2.75(,i)-.715 G 2.75(nc)-2.75 G
(onsidering the use of Quick-Start with CCID 3 for requesting a higher)
-2.75 E(sending rate after an idle period, the follo)100.8 488 Q
(wing questions arise:)-.275 E(\(1\) What rate does the sender request?)
100.8 514 Q(As in TCP)100.8 527 Q 2.75(,t)-1.221 G
(here is a straightforw)-2.75 E
(ard answer to the rate request that the CCID 3 sender)-.11 E
(should use in requesting a higher sending rate after an idle period.)
100.8 540 Q(The sender kno)5.5 E(ws the)-.275 E(current loss e)100.8 553
Q -.165(ve)-.275 G(nt rate, either from its o).165 E
(wn calculations or from feedback from the recei)-.275 E -.165(ve)-.275
G -.44(r,).165 G(and can determine the sending rate allo)100.8 566 Q
(wed by that loss e)-.275 E -.165(ve)-.275 G(nt rate.).165 E
(This is the upper bound)5.5 E
(on the sending rate that should be requested by the CCID 3 sender)100.8
579 Q 5.5(.A)-.605 G(Quick-Start request)-2.75 E(is useful with CCID 3 \
when the sender is coming out of an idle or underutilized period,)100.8
592 Q(because in standard operation CCID 3 does not allo)100.8 605 Q
2.75(wt)-.275 G(he sender to send more than twice as)-2.75 E -.11(fa)
100.8 618 S(st as the recei).11 E -.165(ve)-.275 G 2.75(rh).165 G
(as reported recei)-2.75 E -.165(ve)-.275 G 2.75(di).165 G 2.75(nt)-2.75
G(he most recent feedback message.)-2.75 E
(\(2\) What is the response to loss?)100.8 644 Q
(The response to the loss of Quick-Start pack)100.8 657 Q
(ets should be to return to the sending rate that)-.11 E -.11(wo)100.8
670 S(uld ha).11 E .33 -.165(ve b)-.22 H
(een used if Quick-Start had not been requested.).165 E(\(3\) When does\
 the sender decide there has been no feedback from the recei)100.8 696 Q
-.165(ve)-.275 G(r?).165 E
(As in the case of the initial sending rate, it w)100.8 709 Q
(ould seem prudent to reduce the sending rate if)-.11 E
(no feedback is recei)100.8 722 Q -.165(ve)-.275 G 2.75(df).165 G
(rom the recei)-2.75 E -.165(ve)-.275 G 2.75(ri).165 G 2.75(na)-2.75 G
2.75(tl)-2.75 G(east tw)-2.75 E 2.75(or)-.11 G(ound-trip times.)-2.75 E
(It seems lik)5.5 E(ely)-.11 E(Flo)72 769 Q 210.438
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(C. [P)2.75 F(age 64])-.165
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(April 2007)2.75 E(October 2006)112.127 E(that in this case, the sendin\
g rate should be reduced to the sending rate that w)100.8 85 Q(ould ha)
-.11 E -.165(ve)-.22 G
(been used if no Quick-Start request had been appro)100.8 98 Q -.165(ve)
-.165 G(d.).165 E/F1 11/Times-Bold@0 SF -.22(D.)72 137 S/F2 14
/Times-Bold@0 SF -.28(Po)5.72 G(ssible Router Algorithm).28 E F0(This s\
peci\214cation does not tightly de\214ne the algorithm a router uses wh\
en deciding)100.8 163 Q(whether to appro)100.8 176 Q .33 -.165(ve a Q)
-.165 H(uick-Start Rate Request or whether and ho).165 E 2.75(wt)-.275 G
2.75(or)-2.75 G(educe a Rate)-2.75 E 2.75(Request. A)100.8 189 R
(range of algorithms is lik)2.75 E
(ely useful in this space and we consider the algorithm)-.11 E 2.75(ap)
100.8 202 S(articular router uses to be a local polic)-2.75 E 2.75(yd)
-.165 G 2.75(ecision. In)-2.75 F(addition, we belie)2.75 E .33 -.165
(ve t)-.275 H(hat additional).165 E -.165(ex)100.8 215 S
(perimentation with router algorithms is necessary to ha).165 E .33
-.165(ve a s)-.22 H(olid understanding of the).165 E(dynamics v)100.8
228 Q(arious algorithms impose.)-.275 E(Ho)5.5 E(we)-.275 E -.165(ve)
-.275 G .88 -.44(r, w).165 H 2.75(ep).44 G(ro)-2.75 E
(vide one particular algorithm in this)-.165 E(appendix as an e)100.8
241 Q(xample and as a frame)-.165 E -.11(wo)-.275 G
(rk for thinking about additional mechanisms.).11 E([SAF06] pro)100.8
267 Q(vides se)-.165 E -.165(ve)-.275 G
(ral algorithms routers can use to consider incoming Rate Requests.).165
E(The decision process in)100.8 280 Q -.22(vo)-.44 G(lv).22 E(es tw)
-.165 E 2.75(oa)-.11 G 2.75(lgorithms. First,)-2.75 F
(the router needs to track the link)2.75 E(utilization o)100.8 293 Q
-.165(ve)-.165 G 2.75(rt).165 G(he recent past.)-2.75 E
(Second, this utilization needs to be updated by the)5.5 E(potential ne)
100.8 306 Q 2.75(wb)-.275 G(andwidth from recent Quick-Start appro)-2.75
E -.275(va)-.165 G(ls, and then compared with the).275 E(router')100.8
319 Q 2.75(sn)-.605 G(otion of when it is underutilized enough to appro)
-2.75 E .33 -.165(ve Q)-.165 H(uick-Start requests \(of some).165 E
(size\).)100.8 332 Q(First, we de\214ne the "peak utilization" estimati\
on technique \(from [SAF06]\).)100.8 358 Q(This)5.5 E
(mechanism records the utilization of the link e)100.8 371 Q -.165(ve)
-.275 G(ry S seconds and stores the most recent N).165 E
(of these measurements.)100.8 384 Q(The utilization is then tak)5.5 E
(en as the highest utilization of the N)-.11 E 2.75(samples. This)100.8
397 R(method, therefore, k)2.75 E(eeps N*S seconds of history)-.11 E 5.5
(.T)-.715 G(his algorithm reacts)-5.5 E
(rapidly to increases in the link utilization.)100.8 410 Q
(In [SAF06] S is set to 0.15 seconds, and)5.5 E -.165(ex)100.8 423 S
(periments use v).165 E(alues for N ranging from 3 to 20.)-.275 E
(Second, we de\214ne the "tar)100.8 449 Q
(get" algorithm for processing incoming Quick-Start Rate)-.198 E
(Requests \(also from [SAF06]\).)100.8 462 Q
(The algorithm relies on kno)5.5 E(wing the bandwidth of the)-.275 E
(outgoing link \(which in man)100.8 475 Q 2.75(yc)-.165 G
(ases can be easily con\214gured\), the utilization of the)-2.75 E
(outgoing link \(from an estimation technique such as gi)100.8 488 Q
-.165(ve)-.275 G 2.75(na).165 G(bo)-2.75 E -.165(ve)-.165 G 2.75(\)a)
.165 G(nd an estimate of the)-2.75 E
(potential bandwidth from recent Quick-Start appro)100.8 501 Q -.275(va)
-.165 G(ls.).275 E -.385(Tr)100.8 527 S
(acking the potential bandwidth from recent Quick-Start appro).385 E
-.275(va)-.165 G(ls is another case where).275 E(local polic)100.8 540 Q
2.75(yd)-.165 G(ictates ho)-2.75 E 2.75(wi)-.275 G 2.75(ts)-2.75 G
(hould be done.)-2.75 E(The simplest method, outlined in Section 8.2,)
5.5 E(is for the router to k)100.8 553 Q(eep track of the aggre)-.11 E
-.055(ga)-.165 G(te Quick-Start rate requests appro).055 E -.165(ve)
-.165 G 2.75(di).165 G 2.75(nt)-2.75 G(he)-2.75 E(most recent tw)100.8
566 Q 2.75(oo)-.11 G 2.75(rm)-2.75 G(ore time interv)-2.75 E
(als, including the current time interv)-.275 E(al, and to use the)-.275
E(sum of the aggre)100.8 579 Q -.055(ga)-.165 G(te rate requests o).055
E -.165(ve)-.165 G 2.75(rt).165 G(hese time interv)-2.75 E
(als as the estimate of the appro)-.275 E -.165(ve)-.165 G(d).165 E
(Rate Requests.)100.8 592 Q(The e)5.5 E(xperiments in [SAF06] k)-.165 E
(eep track of the aggre)-.11 E -.055(ga)-.165 G(te appro).055 E -.165
(ve)-.165 G 2.75(dR).165 G(ate)-2.75 E(Requests o)100.8 605 Q -.165(ve)
-.165 G 2.75(rt).165 G(he most recent tw)-2.75 E 2.75(ot)-.11 G
(ime interv)-2.75 E(als, for interv)-.275 E(als of 150~msec.)-.275 E
(The tar)100.8 631 Q(get algorithm also depends on a threshold \(qs_thr\
esh\) that is the fraction of the)-.198 E
(outgoing link bandwidth that represents the router')100.8 644 Q 2.75
(sn)-.605 G(otion of "signi\214cantly underutilized".)-2.75 E(If the ut\
ilization, augmented by the potential bandwidth from recent Quick-Start\
 appro)100.8 657 Q -.275(va)-.165 G(ls,).275 E(is abo)100.8 670 Q .33
-.165(ve t)-.165 H
(his threshold then no Quick-Start Rate Requests will be appro).165 E
-.165(ve)-.165 G 2.75(d. If).165 F(the)2.75 E(utilization, ag)100.8 683
Q
(ain augmented by the potential bandwidth from recent Quick-Start appro)
-.055 E -.275(va)-.165 G(ls,).275 E
(is less than the threshold then Rate Requests can be appro)100.8 696 Q
-.165(ve)-.165 G 2.75(d. The).165 F(Rate Requests will be)2.75 E
(reduced such that the bandwidth allocated w)100.8 709 Q(ould not dri)
-.11 E .33 -.165(ve t)-.275 H(he utilization to more than the).165 E(gi)
100.8 722 Q -.165(ve)-.275 G 2.75(nt).165 G 2.75(hreshold. The)-2.75 F
(algorithm is:)2.75 E(Flo)72 769 Q 209.833
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(D. [P)2.75 F(age 65])-.165
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(April 2007)2.75 E(October 2006)112.127 E
(util_bw = bandwidth * utilization;)106.3 85 Q
(util_bw = util_bw + recent_qs_appro)106.3 98 Q -.275(va)-.165 G(ls;)
.275 E(if \(util_bw < \(qs_thresh * bandwidth\)\))106.3 111 Q({)106.3
124 Q(appro)117.3 137 Q -.165(ve)-.165 G 2.75(d=\().165 G
(qs_thresh * bandwidth\) - util_bw;)-2.75 E(if \(rate_request < appro)
117.3 150 Q -.165(ve)-.165 G(d\)).165 E(appro)128.3 163 Q -.165(ve)-.165
G 2.75(d=r).165 G(ate_request;)-2.75 E(appro)117.3 176 Q -.165(ve)-.165
G 2.75(d=r).165 G(ound_do)-2.75 E(wn \(appro)-.275 E -.165(ve)-.165 G
(d\);).165 E(recent_qs_appro)117.3 189 Q -.275(va)-.165 G(ls += appro)
.275 E -.165(ve)-.165 G(d;).165 E(})106.3 202 Q(Also note that gi)100.8
228 Q -.165(ve)-.275 G 2.75(nt).165 G(hat Rate Requests are f)-2.75 E
(airly coarse, the appro)-.11 E -.165(ve)-.165 G 2.75(dr).165 G
(ate should be)-2.75 E(rounded do)100.8 241 Q(wn when it does not f)
-.275 E(all e)-.11 E(xactly on one of the rates allo)-.165 E
(wed by the encoding)-.275 E(scheme.)100.8 254 Q(Routers that wish to k)
100.8 280 Q
(eep close track of the allocated Quick-Start bandwidth could use)-.11 E
(Appro)100.8 293 Q -.165(ve)-.165 G 2.75(dR).165 G
(ate reports to learn when rate requests had been decremented do)-2.75 E
(wnstream in)-.275 E(the netw)100.8 306 Q
(ork, and also to learn when a sender be)-.11 E(gins to use the appro)
-.165 E -.165(ve)-.165 G 2.75(dQ).165 G(uick-Start)-2.75 E(request.)
100.8 319 Q/F1 11/Times-Bold@0 SF(E.)72 358 Q/F2 14/Times-Bold@0 SF -.28
(Po)5.5 G(ssible Additional Uses f).28 E(or the Quick-Start Option)-.35
E F0(The Quick-Start Option contains a four)100.8 384 Q
(-bit Function \214eld in the third byte, enabling)-.22 E
(additional uses to be de\214ned for the Quick-Start Option.)100.8 397 Q
(In this section we discuss some of)5.5 E
(the possible additional uses that ha)100.8 410 Q .33 -.165(ve b)-.22 H
(een discussed for Quick-Start.).165 E(The Function \214eld)5.5 E(mak)
100.8 423 Q(es it easy to add ne)-.11 E 2.75(wf)-.275 G
(unctions for the Quick-Start Option.)-2.75 E(Report of Current Sending\
 Rate: A Quick-Start Request with the `Report of Current)100.8 449 Q
(Sending Rate' codepoint set in the Function \214eld w)100.8 462 Q
(ould be using the Rate Request \214eld to)-.11 E
(report the current estimated sending rate for that connection.)100.8
475 Q(This could accompan)5.5 E 2.75(ya)-.165 G
(second Quick-Start Request in the same pack)100.8 488 Q
(et containing a standard rate request, for a)-.11 E(connection that is\
 using Quick-Start to increase its current sending rate.)100.8 501 Q(Re\
quest to Increase Sending Rate: A codepoint for `Request to Increase Se\
nding Rate' in)100.8 527 Q(the Function \214eld w)100.8 540 Q
(ould indicate that the connection is not idle or just starting up, b)
-.11 E(ut is)-.22 E
(attempting to use Quick-Start to increase its current sending rate.)
100.8 553 Q(This codepoint w)5.5 E(ould)-.11 E
(not change the semantics of the Rate Request \214eld.)100.8 566 Q -.66
(RT)100.8 592 S 2.75(TE).66 G(stimate: If a codepoint for `R)-2.75 E
(TT Estimate' w)-.66 E(as used, a \214eld for the R)-.11 E(TT Estimate)
-.66 E -.11(wo)100.8 605 S(uld contain one or more bits gi).11 E
(ving the sender')-.275 E 2.75(sr)-.605 G
(ough estimate of the round-trip time, if)-2.75 E(kno)100.8 618 Q 2.75
(wn. E.g.,)-.275 F(the sender could estimate whether the R)2.75 E(TT w)
-.66 E(as greater or less than 200 ms.)-.11 E(Alternately)100.8 631 Q
2.75(,i)-.715 G 2.75(ft)-2.75 G(he sender had an estimate of the R)-2.75
E(TT when it sends the Rate Request, the)-.66 E(tw)100.8 644 Q
(o-bit Reserv)-.11 E(ed \214eld at the end of the Quick-Start Option co\
uld be used for a coarse-)-.165 E(grained encoding of the R)100.8 657 Q
(TT)-.66 E(.)-.814 E(Informational Request: An Informational Request co\
depoint in the Function \214eld w)100.8 683 Q(ould)-.11 E(indicate that\
 a request is purely informational, for the sender to \214nd out if a r\
ate request)100.8 696 Q -.11(wo)100.8 709 S(uld be appro).11 E -.165(ve)
-.165 G(d, and what size rate request w).165 E(ould be appro)-.11 E
-.165(ve)-.165 G(d, when the Informational).165 E(Request is sent.)100.8
722 Q -.165(Fo)5.5 G 2.75(re).165 G
(xample, an Informational Request could be follo)-2.915 E
(wed one round-trip)-.275 E(Flo)72 769 Q 211.054
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(E. [P)2.75 F(age 66])-.165
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E
(time later by a standard Quick-Start Request.)100.8 85 Q 2.75(Ar)5.5 G
(outer appro)-2.75 E(ving an Informational Request)-.165 E -.11(wo)100.8
98 S(uld not consider this as an appro).11 E -.275(va)-.165 G 2.75(lf)
.275 G(or Quick-Start bandwidth to be used, and w)-2.75 E(ould)-.11 E
(not be under an)100.8 111 Q 2.75(yo)-.165 G(blig)-2.75 E
(ation to appro)-.055 E .33 -.165(ve a s)-.165 H
(imilar standard Quick-Start Request one round-).165 E(trip time later)
100.8 124 Q 5.5(.A)-.605 G 2.75(nI)-5.5 G
(nformational Request with a rate request of zero could be used by the)
-2.75 E(sender to \214nd out if all of the routers along the path suppo\
rted Quick-Start.)100.8 137 Q(Use F)100.8 163 Q
(ormat X for the Rate Request Field: A Quick-Start codepoint for `Use F)
-.165 E(ormat X for)-.165 E(the Rate Request Field' w)100.8 176 Q
(ould indicate that an alternate format w)-.11 E
(as being used for the Rate)-.11 E(Request \214eld.)100.8 189 Q(Do Not \
Decrement: A Do Not Decrement codepoint could be used for a Quick-Start)
100.8 215 Q(request where the sender w)100.8 228 Q(ould rather ha)-.11 E
.33 -.165(ve t)-.22 H(he request denied than to ha).165 E .33 -.165
(ve t)-.22 H(he rate request).165 E(decremented in the netw)100.8 241 Q
2.75(ork. This)-.11 F(could be used if the sender w)2.75 E
(as only interested in using)-.11 E
(Quick-Start if the original rate request w)100.8 254 Q(as appro)-.11 E
-.165(ve)-.165 G(d.).165 E -.77(Te)100.8 280 S
(mporary Bandwidth Use: A T).77 E
(emporary codepoint has been proposed to indicate that a)-.77 E
(connection w)100.8 293 Q
(ould only use the requested bandwidth for a single time interv)-.11 E
(al.)-.275 E/F1 14/Times-Bold@0 SF(Normati)72 332 Q .28 -.14(ve R)-.14 H
(efer).14 E(ences)-.252 E F0([RFC793] J. Postel, T)100.8 358 Q
(ransmission Control Protocol, RFC 793, September 1981.)-.385 E
([RFC1191] Mogul, J. and S. Deering, P)100.8 384 Q(ath MTU Disco)-.165 E
-.165(ve)-.165 G(ry).165 E 2.75(,R)-.715 G(FC 1191, No)-2.75 E -.165(ve)
-.165 G(mber 1990.).165 E([RFC2119] Bradner)100.8 410 Q 2.75(,S)-.44 G
(., "K)-2.75 E .33 -.165(ey w)-.275 H
(ords for use in RFCs to Indicate Requirement Le).055 E -.165(ve)-.275 G
(ls",).165 E(BCP 14, RFC 2119, March 1997.)100.8 423 Q
([RFC2460] S. Deering and R. Hinden. Internet Protocol, V)100.8 449 Q
(ersion 6 \(IPv6\) Speci\214cation.)-1.221 E(RFC 2460, December 1998.)
100.8 462 Q([RFC2581] M. Allman, V)100.8 488 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.).165 E(RFC 2581.)5.5 E(April 1999.)100.8
501 Q([RFC3168] Ramakrishnan, K.K., Flo)100.8 527 Q
(yd, S., and Black, D.)-.11 E(The Addition of Explicit)5.5 E
(Congestion Noti\214cation \(ECN\) to IP)100.8 540 Q 5.5(.R)-1.221 G
(FC 3168, Proposed Standard, September 2001.)-5.5 E
([RFC3390] M. Allman, S. Flo)100.8 566 Q(yd, and C. P)-.11 E
(artridge. Increasing TCP')-.165 E 2.75(sI)-.605 G(nitial W)-2.75 E
(indo)-.44 E 1.43 -.715(w. R)-.275 H(FC).715 E(3390, October 2002.)100.8
579 Q([RFC3742] Flo)100.8 605 Q(yd, S., Limited Slo)-.11 E
(w-Start for TCP with Lar)-.275 E(ge Congestion W)-.198 E(indo)-.44 E
(ws, RFC)-.275 E(3742, Experimental, March 2004.)100.8 618 Q F1(Inf)72
657 Q(ormati)-.35 E .28 -.14(ve R)-.14 H(efer).14 E(ences)-.252 E F0([R\
FC792] J. Postel. Internet Control Message Protocol. RFC 792, September\
 1981.)100.8 683 Q 2.75([RFC1321] Ri)100.8 709 R -.165(ve)-.275 G
(st, R., "The MD5 Message-Digest Algorithm", RFC 1321, April 1992.).165
E(Flo)72 769 Q 261.775(yd/Allman/Jain/Sarolahti [P)-.11 F(age 67])-.165
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 77.081(-DRAFT Expires:)-1.012 F
(April 2007)2.75 E(October 2006)112.127 E([RFC1812] F)100.8 85 Q 2.75
(.B)-.88 G(ak)-2.75 E(er \(ed.\). Requirements for IP V)-.11 E
(ersion 4 Routers. RFC 1812, June 1995.)-1.221 E 2.75
([RFC2003] Perkins,)100.8 111 R(C., IP Encapsulation within IP)2.75 E
2.75(,R)-1.221 G(FC 2003, October 1996.)-2.75 E
([RFC2113] D. Katz. P Router Alert Option. RFC 2113, February 1997.)
100.8 137 Q([RFC2140] J. T)100.8 163 Q
(ouch. TCP Control Block Interdependence.)-.88 E(RFC 2140. April 1997.)
5.5 E([RFC2205] R. Braden, et al. Resource ReSerV)100.8 189 Q
(ation Protocol \(RSVP\) -- V)-1.221 E(ersion 1)-1.221 E
(Functional Speci\214cation. RFC 2205, September 1997.)100.8 202 Q
([RFC2409] D. Harkins and D. Carrel, The Internet K)100.8 228 Q .33
-.165(ey E)-.275 H(xchange \(IKE\), RFC 2409,).165 E(No)100.8 241 Q
-.165(ve)-.165 G(mber 1998.).165 E([RFC2415] K. Poduri and K. Nichols. \
Simulation Studies of Increased Initial TCP W)100.8 267 Q(indo)-.44 E(w)
-.275 E(Size. RFC 2415. September 1998.)100.8 280 Q([RFC2463] A. Conta \
and S. Deering. Internet Control Message Protocol \(ICMPv6\) for the)
100.8 306 Q(Internet Protocol V)100.8 319 Q
(ersion 6 \(IPv6\) Speci\214cation. RFC 2463, December 1998.)-1.221 E
([RFC2488] M. Allman, D. Glo)100.8 345 Q -.165(ve)-.165 G .88 -.44(r, a)
.165 H(nd L. Sanchez. Enhancing TCP Ov).44 E(er Satellite)-.165 E
(Channels using Standard Mechanisms. RFC 2488. January 1999.)100.8 358 Q
([RFC2661] W)100.8 384 Q 2.75(.T)-1.012 G -.275(ow)-3.63 G(nsle).275 E
1.43 -.715(y, A)-.165 H 2.75(.V).715 G(alencia, A. Rubens, G. P)-3.971 E
(all, G. Zorn, and B.)-.165 E -.165(Pa)5.5 G(lter).165 E 2.75(,L)-.44 G
(ayer)-2.75 E -1.1 -.88(Tw o)100.8 397 T -.495(Tu)3.63 G
(nneling Protocol "L2TP", RFC 2661, August 1999.).495 E 2.75
([RFC2784] D.)100.8 423 R -.165(Fa)2.75 G(rinacci, T).165 E 2.75(.L)
-.814 G(i, S. Hanks, D. Me)-2.75 E(yer)-.165 E 2.75(,a)-.44 G(nd P)-2.75
E 2.75(.T)-1.221 G(raina, Generic Routing)-3.135 E
(Encapsulation \(GRE\), RFC 2784, March 2000.)100.8 436 Q
([RFC2960] R. Ste)100.8 462 Q -.11(wa)-.275 G
(rt, et al. Stream Control T).11 E
(ransmission Protocol. RFC 2960, October)-.385 E(2000.)100.8 475 Q
([RFC3031] E. Rosen, A. V)100.8 501 Q(isw)-.66 E
(anathan, and R. Callon.)-.11 E(Multiprotocol Label Switching)5.5 E 2.75
(Architecture. RFC)100.8 514 R 2.75(3031. January)2.75 F(2001.)2.75 E
([RFC3124] H. Balakrishnan and S. Seshan. The Congestion Manager)100.8
540 Q 2.75(.R)-.605 G(FC 3124. June)-2.75 E(2001.)100.8 553 Q
([RFC3234] B. Carpenter and S. Brim, Middlebox)100.8 579 Q(es: T)-.165 E
(axonomy and Issues, RFC 3234,)-.88 E(February 2002.)100.8 592 Q([RFC33\
44] C. Perkins \(ed.\). IP Mobility Support for IPv4. RFC 3344, August \
2002.)100.8 618 Q([RFC3360] S. Flo)100.8 644 Q 2.75(yd. Inappropriate)
-.11 F(TCP Resets Considered Harmful.)2.75 E(RFC 3360, August)5.5 E
(2002.)100.8 657 Q([RFC3649] Flo)100.8 683 Q
(yd, S., HighSpeed TCP for Lar)-.11 E(ge Congestion W)-.198 E(indo)-.44
E(ws, RFC 3649,)-.275 E(December 2003.)100.8 696 Q
([RFC3662] R. Bless, K. Nichols, and K. W)100.8 722 Q 2.75(ehrle. A)-.88
F(Lo)2.75 E(wer Ef)-.275 E(fort Per)-.275 E(-Domain Beha)-.22 E(vior)
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G(nd S. Deering. IPv6 Flo)-2.75 E 2.75(wL)-.275 G(abel)-2.75 E
(Speci\214cation. RFC 3697, March 2004.)100.8 124 Q
([RFC3775] D. Johnson, C. Perkins, and J. Arkk)100.8 150 Q
(o. Mobility Support in IPv6. RFC 3775,)-.11 E(June 2004.)100.8 163 Q
([RFC3819] P)100.8 189 Q 2.75(.K)-1.221 G
(arn et al., "Advice for Internet Subnetw)-2.75 E
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215 Q(ander)-.11 E 2.75(,V)-.44 G 2.75(.V)-4.169 G
(olpe, L. DiBurro, and M. Stenber)-4.169 E(g, UDP)-.198 E
(Encapsulation of IPsec ESP P)100.8 228 Q(ack)-.165 E
(ets, RFC 3948, January 2005.)-.11 E([RFC4301] S. K)100.8 254 Q(ent and\
 K. Seo, Security Architecture for the Internet Protocol, RFC 4301,)
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(FC 4302, December 2005.)-2.75 E([RFC4306] Kaufman, C., "Internet K)
100.8 319 Q .33 -.165(ey E)-.275 H
(xchange \(IKEv2\) Protocol", RFC 4306,).165 E(December 2005.)100.8 332
Q([RFC4340] E. K)100.8 358 Q(ohler)-.385 E 2.75(,M)-.44 G 2.75(.H)-2.75
G(andle)-2.75 E 1.43 -.715(y, a)-.165 H(nd S. Flo).715 E
(yd, Datagram Congestion Control Protocol)-.11 E
(\(DCCP\), RFC 4340, March 2006.)100.8 371 Q([RFC4341] S. Flo)100.8 397
Q(yd and E. K)-.11 E(ohler)-.385 E 2.75(,P)-.44 G
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(\(DCCP\) Congestion Control ID 2: TCP-lik)100.8 410 Q 2.75(eC)-.11 G
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([AHO98] M. Allman, C. Hayes and S. Ostermann. An e)100.8 436 Q -.275
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449 Q(indo)-.44 E(ws. A)-.275 E(CM Computer Communication Re)-.44 E(vie)
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100.8 475 Q(vie)-.275 E(w: Quick-Start for TCP and IP)-.275 E 2.75(,i)
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("http://www)100.8 501 Q(.cs.ucl.ac.uk/staf)-.715 E
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([BJCG+05] Briscoe, B., Jacquet, A., Di Cairano-Gilfedder)100.8 527 Q
2.75(,C)-.44 G(., Salv)-2.75 E(atori, A., Soppera, A.,)-.275 E(and M. K)
100.8 540 Q -.11(oy)-.385 G
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(SM)-2.75 E(Phase 2+ General P)100.8 592 Q(ack)-.165 E
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1.43 -.715(v, M)-.165 H 2.75(.P).715 G
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(racing)-.385 E(in a GPRS Netw)100.8 644 Q
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E([H05] P)100.8 683 Q 2.75(.H)-1.221 G(of)-2.75 E
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([L05] Guohan Lu, Nonce in TCP Quick Start, draft, September 2005.)100.8
449 Q(URL)5.5 E("http://www)100.8 462 Q(.net-glyph.or)-.715 E
(g/~lgh/nonce-usage.pdf".)-.198 E([MH06] M. Mathis and J. Hef)100.8 488
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(nternet-draft)-2.75 E(draft-ietf-pmtud-method-07.txt, w)100.8 501 Q
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([MAF04] Alberto Medina, Mark Allman, and Sally Flo)100.8 527 Q
(yd, Measuring Interactions)-.11 E(Between T)100.8 540 Q
(ransport Protocols and Middlebox)-.385 E
(es, Internet Measurement Conference 2004,)-.165 E(August 2004.)100.8
553 Q(URL "http://www)5.5 E(.icir)-.715 E(.or)-.605 E(g/tbit/".)-.198 E
([MAF05] Alberto Medina, Mark Allman, and Sally Flo)100.8 579 Q 2.75
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S(ansport Protocols in the Internet.).385 E(Computer Communications Re)
5.5 E(vie)-.275 E 1.43 -.715(w, A)-.275 H(pril 2005.).715 E
([MaxNet] MaxNet Home P)100.8 618 Q(age, URL "http://netlab)-.165 E
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100.8 657 Q -.275(va)-.275 G(te communication.).275 E
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100.8 683 Q(ABL+05] Ruoming P)-1.012 E(ang, Mark Allman, Mik)-.165 E
2.75(eB)-.11 G(ennett, Jason Lee, V)-2.75 E(ern P)-1.221 E(axson, Brian)
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E 2.75(2002. URL)100.8 111 R("http://www)2.75 E(.icir)-.715 E(.or)-.605
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(W03] Mattia Rossi and Michael W)-.605 E
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(W04] Mattia Rossi and Michael W)-.605 E
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(2005, https://www)100.8 358 Q(.guha.cc/saikat/pub/sigcomm05-lo)-.715 E
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([SHA1] "Secure Hash Standard", FIPS, U.S. Department of Commerce, W)
100.8 384 Q(ashington, D.C.)-.88 E(publication 180-1, April 1995.)100.8
397 Q([SH02] Srikanth Sundarrajan and John Heidemann.)100.8 423 Q
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CC 2000 \(19th IEEE International Performance,)100.8 566 Q(Computing, A\
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100.8 579 Q 2.75(2000. URL)100.8 592 R("http://www)2.75 E
(.welzl.at/research/publications/".)-.715 E([ZDPS01] Y)100.8 618 Q 2.75
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(CM SIGCOMM Internet Measurement W)-.44 E(orkshop, No)-.88 E -.165(ve)
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72 85 S(THORS' ADDRESSES).7 E F0(Sally Flo)100.8 124 Q(yd)-.11 E
(Phone: +1 \(510\) 666-2989)100.8 137 Q
(ICIR \(ICSI Center for Internet Research\))100.8 150 Q(Email: \215o)
100.8 163 Q(yd@icir)-.11 E(.or)-.605 E(g)-.198 E(URL: http://www)100.8
176 Q(.icir)-.715 E(.or)-.605 E(g/\215o)-.198 E(yd/)-.11 E(Mark Allman)
100.8 202 Q(ICSI Center for Internet Research)100.8 215 Q
(1947 Center Street, Suite 600)100.8 228 Q(Berk)100.8 241 Q(ele)-.11 E
1.43 -.715(y, C)-.165 H 2.75(A9).715 G(4704-1198)-2.75 E
(Phone: \(440\) 235-1792)100.8 254 Q(Email: mallman@icir)100.8 267 Q
(.or)-.605 E(g)-.198 E(URL: http://www)100.8 280 Q(.icir)-.715 E(.or)
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(orks)-.11 E(Email : a.jain@f5.com)100.8 332 Q -.165(Pa)100.8 358 S
(si Sarolahti).165 E(Nokia Research Center)100.8 371 Q -1.221(P.)100.8
384 S(O. Box 407)1.221 E(FI-00045 NOKIA GR)100.8 397 Q(OUP)-.44 E
(Finland)100.8 410 Q(Phone: +358 50 4876607)100.8 423 Q
(Email: pasi.sarolahti@iki.\214)100.8 436 Q(Flo)72 769 Q 261.775
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(Full Copyright Statement)72 85 Q F0(Cop)100.8 111 Q
(yright \(C\) The Internet Society 2006.)-.11 E
(This document is subject to the rights, licenses)5.5 E
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(xcept as set forth therein, the authors retain all)-.165 E
(their rights.)100.8 137 Q
(This document and the information contained herein are pro)100.8 163 Q
(vided on an "AS IS" basis and)-.165 E(THE CONTRIB)100.8 176 Q(UT)-.11 E
(OR, THE ORGANIZA)-.198 E(TION HE/SHE REPRESENTS OR IS)-1.221 E
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189 Q(ENGINEERING T)100.8 202 Q(ASK FORCE DISCLAIM ALL W)-1.023 E
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obtained from the IETF on-line IPR repository at)100.8 449 Q(http://www)
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