One document matched: draft-ietf-tsvwg-quickstart-02.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-02.ps ICIR)72 111 R
(Expires: September 2006)72 124 Q(A. Jain)251.998 E(F5 Networks)437.998
137 Q(P. Sarolahti)431.998 150 Q(Nokia Research Center)377.998 163 Q 6
(5M)431.998 176 S(arch 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
(By submitting this Internet-Draft, each author represents that an)100.8
262.6 Q 2.75(ya)-.165 G(pplicable patent or other)-2.75 E
(IPR claims of which he or she is a)100.8 275.6 Q -.11(wa)-.165 G(re ha)
.11 E .33 -.165(ve b)-.22 H(een or will be disclosed, and an).165 E 2.75
(yo)-.165 G 2.75(fw)-2.75 G(hich he)-2.75 E(or she becomes a)100.8 288.6
Q -.11(wa)-.165 G
(re will be disclosed, in accordance with Section 6 of BCP 79.).11 E
(Internet-Drafts are w)100.8 305.2 Q
(orking documents of the Internet Engineering T)-.11 E(ask F)-.88 E
(orce \(IETF\), its)-.165 E(areas, and its w)100.8 318.2 Q
(orking groups.)-.11 E(Note that other groups may also distrib)5.5 E
(ute w)-.22 E(orking)-.11 E(documents as Internet-Drafts.)100.8 331.2 Q
(Internet-Drafts are draft documents v)100.8 347.8 Q
(alid for a maximum of six months and may be)-.275 E
(updated, replaced, or obsoleted by other documents at an)100.8 360.8 Q
2.75(yt)-.165 G 2.75(ime. It)-2.75 F(is inappropriate to use)2.75 E
(Internet-Drafts as reference material or to cite them other than as "w)
100.8 373.8 Q(ork in progress.")-.11 E
(The list of current Internet-Drafts can be accessed at http://www)100.8
390.4 Q(.ietf.or)-.715 E(g/ietf/1id-)-.198 E(abstracts.txt.)100.8 403.4
Q(The list of Internet-Draft Shado)100.8 420 Q 2.75(wD)-.275 G
(irectories can be accessed at)-2.75 E(http://www)100.8 433 Q(.ietf.or)
-.715 E(g/shado)-.198 E -.715(w.)-.275 G(html.).715 E
(This Internet-Draft will e)100.8 449.6 Q(xpire on September 2006.)-.165
E F2(Abstract)72 475.6 Q F3(This document speci\214es an optional Quick\
-Start mechanism for transport protocols, in)100.8 501.6 Q
(cooperation with routers, to determine an allo)100.8 514.6 Q
(wed sending rate at the start and at times in)-.275 E
(the middle of a data transfer \(e.g., after an idle period\).)100.8
527.6 Q(While Quick-Start is designed to)5.5 E(be used by a range of tr\
ansport protocols, in this document we describe its use with TCP)100.8
540.6 Q(.)-1.221 E(By using Quick-Start, a TCP host, say)100.8 553.6 Q
2.75(,h)-.715 G(ost A, w)-2.75 E
(ould indicate its desired sending rate in)-.11 E(bytes per second, usi\
ng a Quick Start option in the IP header of a TCP pack)100.8 566.6 Q
2.75(et. Each)-.11 F(router)2.75 E
(along the path could, in turn, either appro)100.8 579.6 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)100.8 592.6 Q -.165
(ve)-.165 G 2.75(d. If).165 F(the Quick-Start request is not)2.75 E
(appro)100.8 605.6 Q -.165(ve)-.165 G(d, then the sender w).165 E
(ould use the def)-.11 E(ault congestion control mechanisms.)-.11 E(The)
5.5 E(Quick-Start mechanism can determine if there are routers along th\
e path that do not)100.8 618.6 Q
(understand the Quick-Start option, or ha)100.8 631.6 Q .33 -.165(ve n)
-.22 H(ot agreed to the Quick-Start rate request.).165 E(TCP)5.5 E(host\
 B communicates the \214nal rate request to TCP host A in a transport-l\
e)100.8 644.6 Q -.165(ve)-.275 G 2.75(lQ).165 G(uick-Start)-2.75 E
(Response in an answering TCP pack)100.8 657.6 Q 2.75(et. Quick-Start)
-.11 F(is designed to allo)2.75 E 2.75(wc)-.275 G(onnections to use)
-2.75 E(higher sending rates when there is signi\214cant unused bandwid\
th along the path, and all of)100.8 670.6 Q
(the routers along the path support the Quick-Start Request.)100.8 683.6
Q(Flo)72 769 Q 267.275(yd/Allman/Jain/Sarolahti [P)-.11 F(age 1])-.165 E
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(September 2006)2.75 E(March 2006)106.935 E .396 -.198(TO B)100.8 85 T
2.75(ED).198 G(ELETED BY THE RFC EDIT)-2.75 E(OR UPON PUBLICA)-.198 E
(TION:)-1.221 E(Changes from draft-ietf-tsvwg-quickstart-01:)103.55 111
Q 2.75(*A)103.55 124 S(dded a citation to SP)-2.75 E
(AND: Speeding Up Short Data T)-1.012 E(ransfers.)-.385 E 2.75(*A)103.55
137 S(dded a sentence in Section 8.1 on "Implementation Issues for)-2.75
E(Processing Quick-Start Requests" about multi-access links.)109.05 150
Q 2.75(*M)103.55 163 S
(entioned the IP Router Alert option, RFC 2113, in Appendix)-2.75 E
(A.1.1.)109.05 176 Q 2.75(*A)103.55 189 S(dded a discussion of lo)-2.75
E(wer)-.275 E(-than-best-ef)-.22 E(fort service.)-.275 E 2.75(*A)103.55
202 S(dded a fe)-2.75 E 2.75(ws)-.275 G
(entences about the requirements for)-2.75 E(randomness in the nonce.)
109.05 215 Q 2.75(*C)103.55 228 S
(hanged the name of the option from the Quick-Start Request)-2.75 E
(Option to the Quick-Start Option.)109.05 241 Q 2.75(*C)103.55 254 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)
109.05 267 Q(as a request if this \214eld is zero.)109.05 280 Q 2.75(*C)
103.55 293 S(hanged the "Reporting Appro)-2.75 E -.165(ve)-.165 G 2.75
(dR).165 G(ate" option from a)-2.75 E
("Possible Use" in Appendix D to a required use in Section 3.1,)109.05
306 Q(to allo)109.05 319 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)
109.05 332 Q(ving senders.)-.22 E 2.75(*C)103.55 345 S
(hanges from feedback from Bob Briscoe:)-2.75 E 2.75(-A)109.05 358 S
(dded Appendix E with a response to Sections 1-3 of)-2.75 E
(Bob Briscoe')114.55 371 Q 2.75(sd)-.605 G(ocument.)-2.75 E 2.75(-A)
109.05 384 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)114.55 397 Q(fect)-.275 E
(the treatment of the subsequent arri)114.55 410 Q(ving)-.275 E
(Quick-Start data pack)114.55 423 Q(ets.)-.11 E 2.75(-A)109.05 436 S
(dded the one-w)-2.75 E(ay hash function as an alternate)-.11 E
(implementation for the QS Nonce.)114.55 449 Q 2.75(-C)109.05 462 S
(lari\214ed the phrase "incrementally deplo)-2.75 E(yable", adding)-.11
E(the follo)114.55 475 Q(wing:)-.275 E("W)114.55 488 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 can not be appro)114.55 501 Q
-.165(ve)-.165 G(d).165 E
(for a particular connection unless both end-nodes and all)114.55 514 Q
(of the routers along the path ha)114.55 527 Q .33 -.165(ve b)-.22 H
(een con\214gured to).165 E(support Quick-Start.")114.55 540 Q 2.75(-C)
109.05 553 S(lari\214ed semantics about additional rate.)-2.75 E 2.75
(-S)109.05 566 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)114.55 579 Q
(an error code.)114.55 592 Q 2.75(-A)109.05 605 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.)114.55 618 Q 2.75(-M)109.05 631 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)114.55 644
Q(by the same amount that it decrements the IP TTL \(on the)114.55 657 Q
(of)114.55 670 Q 2.75(fc)-.275 G
(hance that it decrements the IP TTL by more than one\).)-2.75 E 2.75
(-F)109.05 683 S(ix)-2.75 E(ed nits.)-.165 E
(Changes from draft-ietf-tsvwg-quickstart-00:)103.55 709 Q 2.75(*A)
103.55 722 S(dded a 30-bit QS Nonce.)-2.75 E
(Based on feedback from Guohan Lu)5.5 E(Flo)72 769 Q 267.275
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(airhurst \(and deleted the te)-.165 E(xt about a possible)-.165 E(four)
109.05 98 Q(-bit QS nonce\).)-.22 E 2.75(*A)103.55 111 S(dded a ne)-2.75
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-2.75 E(from Joe T)114.55 124 Q(ouch and Da)-.88 E(vid Black.)-.22 E
2.75(*R)103.55 137 S -.275(ev)-2.75 G(ised "Quick-Start in IP T).275 E
(unnels" Section, based on feedback)-.495 E(from Joe T)109.05 150 Q
(ouch and Da)-.88 E(vid Black.)-.22 E 2.75(*A)103.55 163 S
(dded a section about "Possible Uses for the Reserv)-2.75 E(ed Fields".)
-.165 E 2.75(*C)103.55 176 S(hanges from feedback from Gorry F)-2.75 E
(airhurst:)-.165 E 2.75(-S)109.05 189 S(ection 4.4, re)-2.75 E
(vised the e)-.275 E(xplanation for reducing the)-.165 E
(congestion windo)114.55 202 Q 2.75(ww)-.275 G(hen the \214rst A)-2.75 E
(CK for a Quick-Start)-.44 E(pack)114.55 215 Q(et is recei)-.11 E -.165
(ve)-.275 G(d.).165 E 2.75(-S)109.05 228 S
(ection 6.4, deleted the last sentence.)-2.75 E 2.75(-M)109.05 241 S
(inor editing changes.)-2.75 E 2.75(-R)109.05 254 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)114.55 267 Q .396 -.198(TO o)-.66 H 2.75(ft)
.198 G(hree seconds.)-2.75 E 2.75(-R)109.05 280 S -.275(ev)-2.75 G
(ised Section 4.6.3 to say that the TCP sender SHOULD use an).275 E
(initial R)114.55 293 Q .396 -.198(TO s)-.66 H(etting of three seconds.)
.198 E 2.75(-A)109.05 306 S(dded te)-2.75 E
(xt to Section 6.2 on Multiple P)-.165 E(aths, discussing)-.165 E
(multi-path routing.)120.05 319 Q 2.75(-C)109.05 332 S
(lari\214ed about GPRS round-trip times.)-2.75 E 2.75(-C)109.05 345 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)109.05 358 S(mall reor)-2.75 E
-.055(ga)-.198 G(nization, rearranging sections.).055 E 2.75(*C)103.55
371 S(hanges from feedback from Martin Duk)-2.75 E(e:)-.11 E 2.75(-R)
109.05 384 S -.275(ev)-2.75 G(ised te).275 E
(xt about the size of QS requests.)-.165 E 2.75(-A)109.05 397 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:)103.55 423 Q 2.75(*As)
103.55 436 S(igni\214cant amount of general editing.)-2.75 E 2.75(*B)
103.55 449 S
(ecause the Rate Request \214eld only uses four bits, speci\214ed)-2.75
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(ed about a)-.11 E(possible use for them.)109.05 475 Q
(This is discussed in a ne)5.5 E 2.75(ws)-.275 G(ection on)-2.75 E
("A Rate-Reduced Nonce?")109.05 488 Q 2.75(*S)103.55 501 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)109.05 514 Q
(possible, SHOULD zero the QS TTL and the Rate Request \214elds.)109.05
527 Q 2.75(*M)103.55 540 S(ade the follo)-2.75 E(wing change:)-.275 E
(If the Quick-Start Response is lost)5.5 E(in the netw)109.05 553 Q
(ork, it is not retransmitted.)-.11 E 2.75(*F)103.55 566 S
(or PMTUD, in Section 4.6, added a suggestion to send one lar)-2.915 E
(ge)-.198 E(pack)109.05 579 Q(et in the initial windo)-.11 E 2.75(wf)
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(ets at 576 bytes.)-.11 E 2.75(*A)103.55 605 S
(dded a paragraph to Section 4.6.3 on retransmitted SYN pack)-2.75 E
(ets,)-.11 E(saying the)109.05 618 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
631 Q(et.)-.11 E 2.75(*A)103.55 644 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)109.05 657
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109.05 670 Q(and in)109.05 683 Q -.165(ve)-.44 G(stig).165 E(ation".)
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(dded an appendix on "Possible Router Algorithm".)-2.75 E 2.75(*M)103.55
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103.55 722 S(ame changed from draft-amit-quick-start-04.txt to)-2.75 E
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124 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)
109.05 137 Q(ork in that paper)-.11 E(.)-.605 E(This w)109.05 150 Q
(ork includes:)-.11 E 2.75(-D)109.05 163 S
(iscussions of router algorithms.)-2.75 E 2.75(-D)109.05 176 S
(iscussions of sizing Quick-Start requests.)-2.75 E 2.75(*A)103.55 189 S
(dded sections on "Misbeha)-2.75 E(ving Middlebox)-.22 E
(es", and on "Attacks on)-.165 E(Quick-Start".)109.05 202 Q
(Changes from draft-amit-quick-start-02.txt:)103.55 228 Q 2.75(*A)103.55
241 S(dded a discussion on Using Quick-Start in the Middle of a)-2.75 E
2.75(Connection. The)109.05 254 R(request w)2.75 E
(ould be on the total rate,)-.11 E(not on the additional rate.)109.05
267 Q 2.75(*C)103.55 280 S
(hanged name "Initial Rate" to "Rate Request", and changed)-2.75 E
(the units from pack)109.05 293 Q(ets per second to bytes per second.)
-.11 E 2.75(*T)103.55 306 S(he follo)-2.75 E(wing sections are ne)-.275
E(w:)-.275 E 2.75(-T)109.05 319 S
(he Quick-Start Request Option for IPv6)-2.75 E 2.75(-Q)109.05 332 S
(uick-Start in IP T)-2.75 E(unnels)-.495 E 2.75(-W)109.05 345 S
(hen to Use Quick-Start)-2.75 E 2.75(-T)109.05 358 S
(CP: Responding to a Loss of a Quick-Start P)-2.75 E(ack)-.165 E(et)-.11
E 2.75(-T)109.05 371 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)109.05 384 S
(CP: A Quick-Start Request after an Idle Period)-2.75 E 2.75(-T)109.05
397 S(he Quick-Start Mechanisms in DCCP and other T)-2.75 E(ransport)
-.385 E(Protocols)114.55 410 Q 2.75(-Q)109.05 423 S
(uick-Start with DCCP)-2.75 E 2.75(-I)109.05 436 S
(mplementation and Deplo)-2.75 E(yment Issues)-.11 E 2.75(-D)109.05 449
S(esign Decisions)-2.75 E 2.75(*A)103.55 462 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)103.55 475 S
(dded a section on simulations, with a brief discussion of the)-2.75 E
(simulations by Srikanth Sundarrajan.)109.05 488 Q
(Changes from draft-amit-quick-start-01.txt:)103.55 514 Q 2.75(*A)103.55
527 S(dded a discussion in the related w)-2.75 E(ork section about the)
-.11 E(possibility of optimistically sending a lar)109.05 540 Q
(ge initial windo)-.198 E -.715(w,)-.275 G(without e)109.05 553 Q
(xplicit permission of routers.)-.165 E 2.75(*A)103.55 566 S
(dded a discussion in the related w)-2.75 E(ork section about the)-.11 E
(tradeof)109.05 579 Q(fs of XCP vs. Quick-Start.)-.275 E 2.75(*A)103.55
592 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:)
103.55 618 Q 2.75(*T)103.55 631 S(he addition of a citation to [KHR02].)
-2.75 E 2.75(*T)103.55 644 S(he addition of a Related W)-2.75 E
(ork section.)-.88 E 2.75(*D)103.55 657 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.)109.05 670 Q(Flo)72 769 Q 267.275
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(September 2006)2.75 E(March 2006)106.935 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(7)
11.5 E(2. Assumptions and General Principles)100.8 122 Q F0 11
(................)10.88 G F2(8)11.5 E(2.1. Ov)115.8 134 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(9)11.5 E(3. The Quick-Start Option in IP)100.8 146 Q F0 11
(..................)12.54 G F2(11)6.5 E
(3.1. The Quick-Start Option for IPv4)115.8 158 Q F0 11
(................)3.66 G F2(11)6.5 E
(3.2. The Quick-Start Option for IPv6)115.8 170 Q F0 11
(................)3.66 G F2(14)6.5 E
(3.3. Processing the Quick-Start Request at Routers)115.8 182 Q F0 11
(............)3.94 G F2(15)6.5 E(3.3.1. Processing the Report of Appro)
130.8 194 Q -.15(ve)-.15 G 2.5(dR).15 G(ate)-2.5 E F0 11(............)
5.08 G F2(16)6.5 E(3.4. The QS Nonce)115.8 206 Q F0 11
(.....................)6.02 G F2(16)6.5 E
(4. The Quick-Start Mechanisms in TCP)100.8 218 Q F0 11
(................)7.82 G F2(18)6.5 E(4.1. When to Use Quick-Start)115.8
230 Q F0 11(..................)5.33 G F2(19)6.5 E
(4.2. The Quick-Start Response Option in the TCP header)115.8 242 Q F0
11(..........)5.89 G F2(20)6.5 E
(4.3. TCP: Sending the Quick-Start Response)115.8 254 Q F0 11
(..............).59 G F2(21)6.5 E(4.4. TCP: Recei)115.8 266 Q
(ving and Using the Quick-Start Response P)-.25 E(ack)-.15 E(et)-.1 E F0
11(........)3.33 G F2(21)6.5 E
(4.5. TCP: Responding to a Loss of a Quick-Start P)115.8 278 Q(ack)-.15
E(et)-.1 E F0 11(..........)10.85 G F2(23)6.5 E
(4.6. TCP: A Quick-Start Request for a Lar)115.8 290 Q(ger Initial W)
-.18 E(indo)-.4 E(w)-.25 E F0 11(.........)2.98 G F2(23)6.5 E
(4.6.1. Interactions with P)130.8 302 Q(ath MTU Disco)-.15 E -.15(ve)
-.15 G(ry).15 E F0 11(............)11.06 G F2(23)6.5 E
(4.6.2. Quick-Start Request P)130.8 314 Q(ack)-.15 E
(ets that are Discarded by Middlebox)-.1 E(es)-.15 E F0 11(.....)6.45 G
F2(24)6.5 E
(4.7. TCP: A Quick-Start Request in the Middle of a Connection)115.8 326
Q F0 11(........)6.71 G F2(25)6.5 E
(4.8. An Example Quick-Start Scenario with TCP)115.8 338 Q F0 11
(............)11.16 G F2(25)6.5 E(5. Quick-Start and IPsec AH)100.8 350
Q F0 11(...................)10.75 G F2(26)6.5 E(6. Quick-Start in IP T)
100.8 362 Q(unnels)-.45 E F0 11(...................)12.85 G F2(26)6.5 E
(6.1. Simple T)115.8 374 Q(unnels That Are Compatible with Quick-Start)
-.45 E F0 11(.........)10.91 G F2(28)6.5 E(6.1.1. Simple T)130.8 386 Q
(unnels that are A)-.45 E -.1(wa)-.92 G(re of Quick-Start).1 E F0 11
(..........)11.26 G F2(28)6.5 E(6.2. Simple T)115.8 398 Q
(unnels That Are Not Compatible with Quick-Start)-.45 E F0 11(........)
7.16 G F2(29)6.5 E(6.3. T)115.8 410 Q(unnels That Support Quick-Start)
-.45 E F0 11(...............)12.02 G F2(30)6.5 E
(7. The Quick-Start Mechanism in other T)100.8 422 Q(ransport Protocols)
-.35 E F0 11(..........)10.69 G F2(30)6.5 E(8. Using Quick-Start)100.8
434 Q F0 11(......................)1.15 G F2(31)6.5 E
(8.1. Determining the Rate to Request)115.8 446 Q F0 11
(................)3.1 G F2(31)6.5 E
(8.2. Deciding the Permitted Rate Request at a Router)115.8 458 Q F0 11
(...........)8.25 G F2(32)6.5 E(9. Ev)100.8 470 Q
(aluation of Quick-Start)-.25 E F0 11(...................)12.38 G F2(32)
6.5 E(9.1. Bene\214ts of Quick-Start)115.8 482 Q F0 11
(...................).18 G F2(32)6.5 E(9.2. Costs of Quick-Start)115.8
494 Q F0 11(...................)10.73 G F2(33)6.5 E
(9.3. Quick-Start with QoS-enabled T)115.8 506 Q(raf)-.35 E<8c63>-.25 E
F0 11(..............)10.94 G F2(34)6.5 E(9.4. Protection ag)115.8 518 Q
(ainst Misbeha)-.05 E(ving Nodes)-.2 E F0 11(..............)7.24 G F2
(34)6.5 E(9.4.1. Misbeha)130.8 530 Q(ving Senders)-.2 E F0 11
(.................)11.77 G F2(35)6.5 E(9.4.2. Recei)130.8 542 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(35)6.5 E(9.4.3. Recei)
130.8 554 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(36)6.5 E
(9.4.4. Collusion between Misbeha)130.8 566 Q(ving Routers)-.2 E F0 11
(............)3.85 G F2(37)6.5 E(9.5. Misbeha)115.8 578 Q
(ving Middlebox)-.2 E(es and the IP TTL)-.15 E F0 11(.............)4.98
G F2(38)6.5 E(9.6. Attacks on Quick-Start)115.8 590 Q F0 11
(...................).74 G F2(38)6.5 E
(9.7. Simulations with Quick-Start)115.8 602 Q F0 11(.................)
3.22 G F2(38)6.5 E(10. Implementation and Deplo)100.8 614 Q
(yment Issues)-.1 E F0 11(...............)6.4 G F2(39)6.5 E
(10.1. Implementation Issues for Sending Quick-Start Requests)115.8 626
Q F0 11(........)11.72 G F2(39)6.5 E
(10.2. Implementation Issues for Processing Quick-Start Requests)115.8
638 Q F0 11(........)1.17 G F2(39)6.5 E(10.3. Possible Deplo)115.8 650 Q
(yment Scenarios)-.1 E F0 11(................)2.64 G F2(40)6.5 E
(10.4. W)115.8 662 Q(ould QuickStart pack)-.8 E(ets tak)-.1 E 2.5(et)-.1
G(he slo)-2.5 E 2.5(wp)-.25 G(ath in routers?)-2.5 E F0 11(.........)
1.18 G F2(41)6.5 E(10.5. A Comparison with the Deplo)115.8 674 Q
(yment Problems of ECN)-.1 E F0 11(.........)6.39 G F2(41)6.5 E
(11. Related W)100.8 686 Q(ork)-.8 E F0 11(.......................).43 G
F2(41)6.5 E(11.1. F)115.8 698 Q
(ast Start-ups without Explicit Information from Routers)-.15 E F0 11
(........)11.02 G F2(42)6.5 E
(11.2. Optimistic Sending without Explicit Information from Routers)
115.8 710 Q F0 11(.......)2.39 G F2(43)6.5 E(11.3. F)115.8 722 Q
(ast Start-ups with other Information from Routers)-.15 E F0 11
(..........)7.42 G F2(43)6.5 E F0(Flo)72 769 Q 267.275
(yd/Allman/Jain/Sarolahti [P)-.11 F(age 5])-.165 E 0 Cg EP
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(11.4. F)115.8 84 Q
(ast Start-ups with more Fine-Grained Feedback from Routers)-.15 E F0 11
(.......)2.3 G F1(44)6.5 E(11.5. F)115.8 96 Q(ast Start-ups with Lo)-.15
E(wer)-.25 E(-Than-Best-Ef)-.2 E(fort Service)-.25 E F0 11(..........)
3.7 G F1(44)6.5 E(12. Security Considerations)100.8 108 Q F0 11
(....................).87 G F1(45)6.5 E(13. Conclusions)100.8 120 Q F0
11(.......................)6 G F1(45)6.5 E(14. Ackno)100.8 132 Q
(wledgements)-.25 E F0 11(.....................)3.77 G F1(46)6.5 E
(A. Design Decisions)100.8 144 Q F0 11(......................)1.71 G F1
(46)6.5 E
(A.1. Alternate Mechanisms for the Quick-Start Request: ICMP and RSVP)
115.8 156 Q F0 11(.....)6.03 G F1(46)6.5 E(A.1.1. ICMP)130.8 168 Q F0 11
(......................)2.53 G F1(46)6.5 E(A.1.2. RSVP)130.8 180 Q F0 11
(......................)1.97 G F1(47)6.5 E
(A.2. Alternate Encoding Functions)115.8 192 Q F0 11(................)
11.99 G F1(48)6.5 E(A.3. The Quick-Start Request: P)115.8 204 Q(ack)-.15
E(ets or Bytes?)-.1 E F0 11(............)11.42 G F1(49)6.5 E
(A.4. Quick-Start Semantics: T)115.8 216 Q
(otal Rate or Additional Rate?)-.8 E F0 11(.........)10.16 G F1(50)6.5 E
(A.5. Alternate Responses to the Loss of a Quick-Start P)115.8 228 Q
(ack)-.15 E(et)-.1 E F0 11(.........)4.07 G F1(51)6.5 E(A.6. Wh)115.8
240 Q 2.5(yN)-.05 G(ot Include More Functionality?)-2.5 E F0 11
(..............)5.66 G F1(51)6.5 E
(A.7. Alternate Implementations for a QuickStart Nonce)115.8 252 Q F0 11
(..........)12.02 G F1(54)6.5 E
(A.7.1. An Alternate Proposal for the QuickStart Nonce)130.8 264 Q F0 11
(.........)12.99 G F1(54)6.5 E(A.7.2. The Earlier Request-Appro)130.8
276 Q -.15(ve)-.15 G 2.5(dQ).15 G(uickStart Nonce)-2.5 E F0 11
(.........)8.3 G F1(55)6.5 E(B. Quick-Start with DCCP)100.8 288 Q F0 11
(....................)4.47 G F1(55)6.5 E(C. Possible Router Algorithm)
100.8 300 Q F0 11(...................)6.55 G F1(57)6.5 E
(D. Possible Additional Uses for the Quick-Start Option)100.8 312 Q F0
11(............).6 G F1(58)6.5 E(E. Feedback from Bob Briscoe)100.8 324
Q F0 11(...................)1.86 G F1(59)6.5 E(E.1. Potential Deplo)
115.8 336 Q(yment Scenarios)-.1 E F0 11(................)4.31 G F1(59)
6.5 E(E.2. Misbeha)115.8 348 Q(ving Senders and Recei)-.2 E -.15(ve)-.25
G(rs).15 E F0 11(...............)2.19 G F1(60)6.5 E(E.3. F)115.8 360 Q
(airness)-.15 E F0 11(.......................)3.66 G F1(60)6.5 E
(E.4. Models of Under)115.8 372 Q(-Utilization)-.2 E F0 11
(.................)5.11 G F1(61)6.5 E
(E.5. Router Algorithms as Local Polic)115.8 384 Q(y)-.15 E F0 11
(...............)7.55 G F1(61)6.5 E(E.6. An Alternate Proposal)115.8 396
Q F0 11(...................)2.41 G F1(62)6.5 E(Normati)100.8 408 Q .3
-.15(ve R)-.25 H(eferences).15 E F0 11(.....................)8.66 G F1
(62)6.5 E(Informati)100.8 420 Q .3 -.15(ve R)-.25 H(eferences).15 E F0
11(.....................)4.22 G F1(62)6.5 E 1.6 -.8(F. I)100.8 432 T(AN)
.8 E 2.5(AC)-.35 G(onsiderations)-2.5 E F0 11(.....................)1.05
G F1(67)6.5 E -.8(F.)115.8 444 S(1. IP Option).8 E F0 11
(......................)12.77 G F1(67)6.5 E -.8(F.)115.8 456 S
(2. TCP Option).8 E F0 11(......................)3.32 G F1(67)6.5 E -.55
(AU)100.8 468 S(THORS' ADDRESSES).55 E F0 11(....................)1.97 G
F1(67)6.5 E(Full Cop)100.8 480 Q(yright Statement)-.1 E F0 11
(....................)10.12 G F1(69)6.5 E(Intellectual Property)100.8
492 Q F0 11(......................)2.27 G F1(69)6.5 E F0(Flo)72 769 Q
267.275(yd/Allman/Jain/Sarolahti [P)-.11 F(age 6])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 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 connection)5.5 E
(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 appropriate in the current netw)100.8 332 Q(ork conditions.)-.11 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(The Congestion Manager [RFC3124] and TCP control block sharing \
[RFC2140] both)100.8 449 Q(propose sharing congestion information among\
 multiple TCP connections with the same)100.8 462 Q 2.75(endpoints. W)
100.8 475 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)100.8 488 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)
100.8 501 Q 4.18 -.715(w. R)-.275 H(FC 2140).715 E
(discusses ensemble sharing, where an established connection')100.8 514
Q 2.75(sc)-.605 G(ongestion windo)-2.75 E 2.75(wc)-.275 G(ould)-2.75 E
(be `di)100.8 527 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)100.8 540 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.)100.8 553 Q(Quick-Start w)100.8 579 Q
(ould not be the \214rst mechanism for e)-.11 E
(xplicit communication from routers to)-.165 E
(transport protocols about sending rates.)100.8 592 Q
(Explicit Congestion Noti\214cation \(ECN\) gi)5.5 E -.165(ve)-.275 G(s)
.165 E -.165(ex)100.8 605 S(plicit congestion control feedback from rou\
ters to transport protocols, based on the).165 E
(router detecting congestion before b)100.8 618 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
631 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)100.8 644 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)100.8 657 Q .33 -.165(ve o)-.275 H(utput).165 E
(links are signi\214cantly underutilized.)100.8 670 Q(Flo)72 769 Q
217.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(1. [P)2.75 F
(age 7])-.165 E 0 Cg EP
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85 Q/F2 14/Times-Bold@0 SF(Assumptions and General Principles)5.5 E F0(\
This section describes the assumptions and general principles behind th\
e design of the)100.8 111 Q(Quick-Start mechanism.)100.8 124 Q
(Assumptions:)100.8 150 Q 2.75(*T)100.8 176 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)100.8 189 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)100.8 202 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)
100.8 228 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)100.8 241 Q
(ets one round-)-.11 E(trip time later)100.8 254 Q 5.5(.[)-.605 G
(ZPS00] sho)-5.5 E(ws this assumption should be generally v)-.275 E
(alid, although)-.275 E
([RFC3819] discusses a range of Bandwidth on Demand subnets.)100.8 267 Q
2.75(*A)100.8 293 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.)100.8 306 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)100.8 319 Q 2.75(semantics. W)100.8 332 R 2.75(en)-.88 G
(ote that while Quick-Start is incrementally deplo)-2.75 E
(yable in this sense, a)-.11 E(Quick-Start request can not be appro)
100.8 345 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)100.8 358 Q .33 -.165(ve b)
-.22 H(een con\214gured to support Quick-Start.).165 E
(General Principles:)100.8 384 Q 2.75(*O)100.8 410 S
(ur underlying premise is that e)-2.75 E
(xplicit feedback from all of the routers along the path)-.165 E -.11
(wo)100.8 423 S
(uld be required, in the current architecture, for best-ef).11 E
(fort connections to use initial)-.275 E(windo)100.8 436 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.)100.8 449 Q 2.75(*Ar)100.8 475 S
(outer should only appro)-2.75 E .33 -.165(ve a r)-.165 H
(equest for a higher sending rate if the output link is).165 E 2.75
(underutilized. An)100.8 488 R 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)
-2.75 E(possibility of a \(possibly transient\) queue at the router)
100.8 501 Q(.)-.605 E 2.75(*N)100.8 527 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)100.8 540 Q
(-\215o)-.22 E 2.75(ws)-.275 G(tate for making Quick-)-2.75 E
(Start decisions or for checking for misbeha)100.8 553 Q(ving nodes.)
-.22 E(There are also a number of questions re)100.8 579 Q -.055(ga)
-.165 G(rding the Quick-Start mechanism that are).055 E
(discussed later in this document.)100.8 592 Q(Questions:)100.8 618 Q
2.75(*W)100.8 644 S
(ould the bene\214ts of the Quick-Start mechanism be w)-3.63 E
(orth the added comple)-.11 E(xity?)-.165 E(The bene\214ts and dra)100.8
670 Q
(wbacks of Quick-Start are discussed in more detail in Section 9 on)
-.165 E("Ev)100.8 683 Q(aluation of Quick-Start".)-.275 E 2.75(*O)100.8
709 S(ne practical consideration is that pack)-2.75 E(ets with kno)-.11
E(wn and unkno)-.275 E(wn IP options are often)-.275 E
(dropped in the current Internet [MAF04].)100.8 722 Q(Flo)72 769 Q
217.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(2. [P)2.75 F
(age 8])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E 1.76 -.88(We n)100.8 85 T
(ote that this does not preclude using Quick-Start in Intranets.).88 E
(Further)5.5 E 2.75(,[)-.44 G(MAF04] also)-2.75 E(sho)100.8 98 Q
(ws that o)-.275 E -.165(ve)-.165 G 2.75(rt).165 G
(ime the blocking of pack)-2.75 E(ets ne)-.11 E
(gotiating ECN has become less common,)-.165 E
(and therefore an incremental deplo)100.8 111 Q
(yment story for Quick-Start based on IP Options is not)-.11 E
(out of the question for the Internet.)100.8 124 Q
(Appendix A.1 on "Alternate Mechanisms for the)5.5 E(Quick-Start Reques\
t" discusses the possibility of using RSVP or ICMP instead of IP)100.8
137 Q(Options for carrying Quick-Start Requests to routers.)100.8 150 Q
2.75(*As)100.8 176 S
(econd practical consideration is that Quick-Start data pack)-2.75 E
(ets could be dropped at)-.11 E(non-IP queues along the path, if the no\
n-IP queue is a point of congestion.)100.8 189 Q(This is)5.5 E
(discussed in more detail in Section 9.2.)100.8 202 Q 2.75(*A)100.8 228
S(part from the merits and shortcomings of the Quick-Start mechanism, i\
s there lik)-2.75 E(ely to)-.11 E(be a compelling need to add e)100.8
241 Q(xplicit congestion-related feedback from routers o)-.165 E -.165
(ve)-.165 G 2.75(ra).165 G(nd)-2.75 E(abo)100.8 254 Q .33 -.165(ve t)
-.165 H(he one-bit feedback from ECN?).165 E
(If the answer to the question abo)100.8 280 Q .33 -.165(ve i)-.165 H
2.75(sy).165 G(es, should we be considering w)-2.75 E
(ays to incorporate)-.11 E
(Quick-Start in mechanisms that, while more comple)100.8 293 Q
(x, are also suf)-.165 E(\214ciently more po)-.275 E(werful)-.275 E(tha\
n Quick-Start, or should Quick-Start be considered as orthogonal to suc\
h mechanisms?)100.8 306 Q
(This is discussed further in Appendix A.6 on "Wh)100.8 319 Q 2.75(yN)
-.055 G(ot Include More Functionality".)-2.75 E/F1 11/Times-Bold@0 SF
(2.1.)72 358 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)100.8 384 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)100.8 397 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)100.8 410 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)100.8 423 Q(for the initial sending rate; these uses of Quick\
-Start are discussed later in the document.)100.8 436 Q
(Quick-Start requires end-points and routers to w)100.8 462 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)100.8 475 Q
2.75(,a)-1.221 G(nd routers along the path)-2.75 E(appro)100.8 488 Q
(ving, modifying, discarding or ignoring \(and therefore disallo)-.165 E
(wing\) the Quick-Start)-.275 E 2.75(Request. The)100.8 501 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.)100.8 514 Q
(In addition, Quick-Start assumes a unicast, congestion-)5.5 E(controll\
ed transport protocol; we do not consider the use of Quick-Start for mu\
lticast)100.8 527 Q(traf)100.8 540 Q(\214c.)-.275 E(When sent as a requ\
est, the Quick-Start Option includes a request for a sending rate in)
100.8 566 Q(bytes per second, and a Quick-Start TTL \(QS TTL\) to be de\
cremented by e)100.8 579 Q -.165(ve)-.275 G(ry router).165 E
(along the path that understands the option and appro)100.8 592 Q -.165
(ve)-.165 G 2.75(st).165 G(he request.)-2.75 E(The Quick-Start TTL)5.5 E
(is initialized by the sender to a random v)100.8 605 Q 2.75(alue. The)
-.275 F(transport recei)2.75 E -.165(ve)-.275 G 2.75(rr).165 G
(eturns the rate and)-2.75 E
(information about the TTL to the sender using transport-le)100.8 618 Q
-.165(ve)-.275 G 2.75(lm).165 G 2.75(echanisms. In)-2.75 F(particular)
2.75 E(,)-.44 E(the recei)100.8 631 Q -.165(ve)-.275 G 2.75(rc).165 G
(omputes the dif)-2.75 E
(ference between the Quick-Start TTL and the IP TTL \(the)-.275 E
(TTL in the IP header\) of the Quick-Start request pack)100.8 644 Q
(et, and returns this in the Quick-Start)-.11 E 2.75(response. The)100.8
657 R(sender uses this information to determine if all of the routers a\
long the path)2.75 E(decremented the Quick-Start TTL, appro)100.8 670 Q
(ving the Quick-Start Request.)-.165 E(If the request is appro)100.8 696
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)100.8 709 Q
(wed rate with the measurement of the round-trip time, and ends up with)
-.275 E(an allo)100.8 722 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(Flo)72 769 Q 209.525
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(2.1. [P)2.75 F(age 9])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(trip time, or until an A)
100.8 85 Q(CK pack)-.44 E(et is recei)-.11 E -.165(ve)-.275 G(d.).165 E
(Figure 1 sho)100.8 111 Q(ws a successful use of Quick-Start, with both\
 routers along the path appro)-.275 E(ving)-.165 E
(the Quick-Start Request.)100.8 124 Q(In this e)5.5 E
(xample, Quick-Start is used by TCP to establish the)-.165 E
(initial congestion windo)100.8 137 Q -.715(w.)-.275 G/F1 11/Courier@0
SF 46.2(Sender Router)120.6 169 R 46.2(1R)6.6 G(outer 2)-46.2 E
(Receiver)66 E 46.2(------ --------)120.6 182 R 59.4(-------- --------)
46.2 F 6.6(|<)107.4 195 S(IP TTL: 63>)-6.6 E 6.6(|<)107.4 208 S
(QS TTL: 91>)-6.6 E 6.6(|<)107.4 221 S(TTL Diff: 28>)-6.6 E 6.6(|Q)107.4
234 S(uick-Start Request)-6.6 E 6.6(|i)107.4 247 S 6.6(nS)-6.6 G
(YN or SYN/ACK -->)-6.6 E(|)107.4 260 Q 99(|D)107.4 273 S(ecrement)-99 E
99(|Q)107.4 286 S 6.6(ST)-99 G(TL)-6.6 E 99(|t)107.4 299 S 6.6(oa)-99 G
(pprove)-6.6 E 99(|r)107.4 312 S(equest -->)-99 E(|)107.4 325 Q 198(|D)
107.4 338 S(ecrement)-198 E 198(|Q)107.4 351 S 6.6(ST)-198 G(TL)-6.6 E
198(|t)107.4 364 S 6.6(oa)-198 G(pprove)-6.6 E 198(|r)107.4 377 S
(equest -->)-198 E(|)107.4 390 Q 283.8(|<)107.4 403 S(IP TTL: 61>)-283.8
E 283.8(|<)107.4 416 S(QS TTL: 89>)-283.8 E 283.8(|<)107.4 429 S
(TTL Diff: 28>)-283.8 E 283.8(|R)107.4 442 S(eturn Quick-Start)-283.8 E
290.4(|i)107.4 455 S(nfo to sender in)-290.4 E 277.2(|<)107.4 468 S
(-- TCP ACK packet.)-277.2 E(|)107.4 481 Q 6.6(|<)107.4 494 S
(TTL Diff: 28>)-6.6 E 6.6(|Q)107.4 507 S(uick-Start approved,)-6.6 E 6.6
(|t)107.4 520 S(ranslate to cwnd.)-6.6 E 6.6(|R)107.4 533 S
(eport Approved Rate.)-6.6 E 6.6(VS)107.4 546 S
(end cwnd paced over one RTT. -->)-6.6 E
(Figure 1: A successful Quick-Start Request.)173.4 572 Q F0
(Figure 2 sho)100.8 604 Q(ws an unsuccessful use of Quick-Start, with o\
ne of the routers along the path)-.275 E(not appro)100.8 617 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)100.8 630 Q
(ault congestion control mechanisms for that transport protocol,)-.11 E
(including the def)100.8 643 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 10])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 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(|)107.4 176 Q 99(|D)107.4 189 S(ecrement)-99 E
99(|Q)107.4 202 S 6.6(ST)-99 G(TL)-6.6 E 99(|t)107.4 215 S 6.6(oa)-99 G
(pprove)-6.6 E 99(|r)107.4 228 S(equest -->)-99 E(|)107.4 241 Q 198(|F)
107.4 254 S(orward packet)-198 E 198(|w)107.4 267 S(ithout modifying)
-198 E 198(|Q)107.4 280 S(uick-Start Option. -->)-198 E(|)107.4 293 Q
283.8(|<)107.4 306 S(IP TTL: 61>)-283.8 E 283.8(|<)107.4 319 S
(QS TTL: 90>)-283.8 E 283.8(|<)107.4 332 S(TTL Diff: 29>)-283.8 E 283.8
(|R)107.4 345 S(eturn Quick-Start)-283.8 E 290.4(|i)107.4 358 S
(nfo to sender in)-290.4 E 277.2(|<)107.4 371 S(-- TCP ACK packet.)
-277.2 E(|)107.4 384 Q 6.6(|<)107.4 397 S(TTL Diff: 29>)-6.6 E 6.6(|Q)
107.4 410 S(uick-Start not approved.)-6.6 E 6.6(|R)107.4 423 S
(eport Approved Rate.)-6.6 E 6.6(VU)107.4 436 S
(se default initial cwnd. -->)-6.6 E
(Figure 2: An unsuccessful Quick-Start Request.)173.4 462 Q/F2 11
/Times-Bold@0 SF(3.)72 507 Q/F3 14/Times-Bold@0 SF
(The Quick-Start Option in IP)5.5 E F2(3.1.)72 546 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)100.8 572 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 11])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 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(|)19.8 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)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 contains\
 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(The QS TTL is used by the sender to detect if \
all of the routers along the path)5.5 E(understood and appro)100.8 416 Q
-.165(ve)-.165 G 2.75(dt).165 G(he Quick-Start option.)-2.75 E -.165(Fo)
100.8 442 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)100.8 455 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)100.8 468 Q(et, as follo)-.11 E(ws:)-.275 E(TTL Dif)100.8
494 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)100.8 520 S 2.75(raR).165 G
(ate Request, the second four bytes contain a 30-bit QS Nonce and a tw)
-2.75 E(o-bit)-.11 E(Reserv)100.8 533 Q(ed \214eld.)-.165 E
(The sender SHOULD set the reserv)5.5 E
(ed \214eld to zero, and routers SHOULD)-.165 E(ignore the reserv)100.8
546 Q(ed \214eld.)-.165 E
(The sender SHOULD set the 30-bit QS Nonce to a random)5.5 E -.275(va)
100.8 559 S(lue.).275 E(The sender initializes the Rate Request to the \
desired sending rate, including an estimate of)100.8 585 Q
(the transport and IP header o)100.8 598 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)100.8 611 Q
(alue in the Rate Request \214eld, and)-.275 E(for K set to 40,000.)
100.8 624 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.)100.8 637 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.)100.8 650 Q
(Alternate encodings that were considered)5.5 E
(for the Rate Request are gi)100.8 663 Q -.165(ve)-.275 G 2.75(ni).165 G
2.75(nA)-2.75 G(ppendix A.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 12])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 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 191.4(|N)100.8 513 S(ot Used)-191.4 E(|)171.6 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)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 the\
 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 last \214v)-2.75 E 2.75(eb)-.165 G
(ytes of the Quick-Start Option are)-2.75 E(not used.)100.8 649 Q
(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 2.75(ate. The)
-2.75 F(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)-2.75 E 2.75(ac)100.8 714 S
(ontrol pack)-2.75 E(et sent before the \214rst Quick-Start data pack)
-.11 E(et, or a Quick-Start Option in the)-.11 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.1. [P)2.75 F(age 13])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E(\214rst data pack)100.8 85 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)-2.75 E -.165(ex)100.8 98 S
(ample, if the appro).165 E -.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)-.11 E(necessarily kno)100.8 111 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(ork.)-.11 E
(If the Rate Request is denied, the sender MUST sent a Report of Appro)
100.8 137 Q -.165(ve)-.165 G 2.75(dR).165 G(ate with the)-2.75 E
(Rate Report \214eld set to zero.)100.8 150 Q 1.76 -.88(We n)100.8 176 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
189 Q(ha)100.8 202 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)100.8 215 Q
(is *not* a request for an additional sending rate o)100.8 228 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)100.8 241 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)100.8 254 Q -.165(ve)
-.275 G(rts to the def).165 E(ault congestion control)-.11 E
(mechanisms of the transport protocol.)100.8 267 Q 1.76 -.88(We n)100.8
293 T(ote that in IPv4, a change in IP options at routers requires reca\
lculating the IP header).88 E(checksum.)100.8 306 Q/F1 11/Times-Bold@0
SF(3.2.)72 345 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)
100.8 371 Q(xtension header)-.165 E(that is processed at e)100.8 384 Q
-.165(ve)-.275 G(ry netw).165 E
(ork node along the communication path [RFC 2460]. The)-.11 E
(option format follo)100.8 397 Q
(wing the generic Hop-by-Hop Options header is identical to the IPv4)
-.275 E(format, with the e)100.8 410 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.)100.8 423 Q -.165(Fo)100.8
449 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 in order to calculate the TTL Dif)100.8
462 Q 2.75(f. \(The)-.275 F(Hop Limit in IPv6 is the)2.75 E(equi)100.8
475 Q -.275(va)-.275 G(lent of the TTL in IPv4.\)).275 E
(That is, TTL Dif)5.5 E 2.75(fM)-.275 G(UST be calculated and stored as)
-2.75 E(follo)100.8 488 Q(ws:)-.275 E(TTL Dif)100.8 514 Q 2.75(f=\(I)
-.275 G(Pv6 Hop Limit - QS TTL \) mod 256)-2.75 E(\(2\))49.5 E(Unlik)
100.8 540 Q 2.75(eI)-.11 G(Pv4, modifying or deleting the Quick-Start I\
Pv6 Option does not require checksum)-2.75 E
(re-calculation, because the IPv6 header does not ha)100.8 553 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)
100.8 566 Q(fect the IPv6)-.275 E(pseudo-header checksum used in upper)
100.8 579 Q(-layer checksum calculations.)-.22 E
(Note that [RFC2460] speci\214es that when a speci\214c \215o)100.8 605
Q 2.75(wl)-.275 G(abel has been assigned to pack)-2.75 E(ets,)-.11 E
(the contents of the Hop-by-Hop options, e)100.8 618 Q(xcluding the ne)
-.165 E(xt header \214eld, must originate)-.165 E
(with the same contents throughout the IP \215o)100.8 631 Q 2.75(wl)
-.275 G 2.75(ifetime. Ho)-2.75 F(we)-.275 E -.165(ve)-.275 G .88 -.44
(r, t).165 H(he Quick-Start option).44 E -.11(wo)100.8 644 S
(uld be included in only a small fraction of the pack).11 E
(ets during a \215o)-.11 E 2.75(wl)-.275 G 2.75(ifetime. Thus,)-2.75 F
(Quick-Start SHOULD NO)100.8 657 Q 2.75(Tb)-.44 G 2.75(eu)-2.75 G
(sed in an IPv6 connection that uses \215o)-2.75 E 2.75(wl)-.275 G
(abels unless the)-2.75 E -.165(ex)100.8 670 S
(perimental speci\214cation of \215o).165 E 2.75(wl)-.275 G
(abels in Appendix A of RFC 2460 is changed.)-2.75 E 1.76 -.88(We n)5.5
H(ote).88 E(that RFC 2460 states that the use of the \215o)100.8 683 Q
2.75(wl)-.275 G(abel \214eld in IPv6 "is, at the time of writing,)-2.75
E(still e)100.8 696 Q
(xperimental and subject to change as the requirements for \215o)-.165 E
2.75(ws)-.275 G(upport in the Internet)-2.75 E
(become clearer" [RFC2460].)100.8 709 Q(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.2. [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 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF(3.3.)
72 85 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)100.8 111 Q(the request; in the def)100.8 124 Q
(ault case of a router that does not maintain per)-.11 E(-\215o)-.22 E
2.75(ws)-.275 G(tate, a router)-2.75 E(mak)100.8 137 Q(es the conserv)
-.11 E(ati)-.275 E .33 -.165(ve a)-.275 H(ssumption that the \215o).165
E(w')-.275 E 2.75(sc)-.605 G(urrent sending rate is zero.)-2.75 E(Each)
5.5 E(participating router can either terminate or appro)100.8 150 Q .33
-.165(ve t)-.165 H(he Quick-Start Request.).165 E 2.75(Ar)5.5 G(outer)
-2.75 E(should only appro)100.8 163 Q .33 -.165(ve a Q)-.165 H
(uick-Start request if the output link is underutilized, and if the).165
E(router judges that the output link will continue to be underutilized \
if the request is)100.8 176 Q(appro)100.8 189 Q -.165(ve)-.165 G 2.75
(d. Otherwise,).165 F(the router terminates the Quick-Start Request.)
2.75 E 2.75(Ar)100.8 215 S(outer that wishes to terminate the Quick-Sta\
rt Request SHOULD delete the Quick-Start)-2.75 E
(Request from the IP header)100.8 228 Q 5.5(.T)-.605 G(his sa)-5.5 E
-.165(ve)-.22 G 2.75(sr).165 G(esources as do)-2.75 E
(wnstream routers will ha)-.275 E .33 -.165(ve n)-.22 H(o).165 E
(option to process.)100.8 241 Q
(If a Quick-Start-capable router wishes to den)5.5 E 2.75(yt)-.165 G
(he request b)-2.75 E(ut doesn')-.22 E(t)-.198 E
(delete the Quick-Start Request from the IP header)100.8 254 Q 2.75(,t)
-.44 G(hen the router SHOULD zero the QS)-2.75 E
(TTL, QS Nonce, and Rate Request \214elds.)100.8 267 Q
(Zeroing the Rate Request \214eld may be more)5.5 E(ef)100.8 280 Q(\214\
cient for routers to implement than deleting the Quick-Start option.)
-.275 E(As suggested in)5.5 E([B05], future additions to Quick-Start co\
uld de\214ne error codes for routers to insert into the)100.8 293 Q(QS \
Nonce \214eld to report back to the sender the reason that the Quick-St\
art request w)100.8 306 Q(as)-.11 E
(denied, e.g., that the router is den)100.8 319 Q
(ying all Quick-Start requests at this time, or that this)-.165 E
(router as a matter of polic)100.8 332 Q 2.75(yd)-.165 G
(oes not grant Quick-Start requests.)-2.75 E 2.75(Ar)5.5 G
(outer that doesn')-2.75 E(t)-.198 E
(understand the Quick-Start option will simply forw)100.8 345 Q
(ard the pack)-.11 E(et with the Quick-Start)-.11 E(Request unchanged.)
100.8 358 Q(If the participating router has decided to appro)100.8 384 Q
.33 -.165(ve t)-.165 H(he Quick-Start Request, it does the).165 E(follo)
100.8 397 Q(wing:)-.275 E 2.75(*T)100.8 423 S
(he router MUST decrement the QS TTL by one.)-2.75 E 2.75(*I)100.8 449 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)
100.8 462 Q 2.75(alue. The)-.275 F(router MUST)2.75 E(NO)100.8 475 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.)100.8 488 Q 2.75
(*I)100.8 514 S 2.75(nI)-2.75 G
(Pv4, the router MUST update the IP header checksum.)-2.75 E
(If the router appro)100.8 540 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
553 Q 2.75(sd)-.605 G
(ecision to accept or reject subsequent Quick-Start requests \(e.g., in)
-2.75 E 2.75(av)100.8 566 S(ariable that tracks the recent aggre)-3.025
E -.055(ga)-.165 G(te of accepted Quick-Start bandwidth\), b).055 E
(ut this)-.22 E(appro)100.8 579 Q -.275(va)-.165 G 2.75(lS).275 G
(HOULD NO)-2.75 E 2.75(Tb)-.44 G 2.75(eu)-2.75 G
(sed by the router to af)-2.75 E(fect the treatment of the data pack)
-.275 E(ets)-.11 E(that arri)100.8 592 Q .33 -.165(ve f)-.275 H
(rom this connection in the ne).165 E(xt fe)-.165 E 2.75(wr)-.275 G
(ound-trip times.)-2.75 E(That is, the appro)5.5 E -.275(va)-.165 G 2.75
(lb).275 G(y)-2.75 E(the router of a Quick-Start request does not gi)
100.8 605 Q .33 -.165(ve d)-.275 H(if).165 E
(ferential treatment for Quick-Start data)-.275 E(pack)100.8 618 Q(ets \
at that router; it is only a statement from the router that the router \
belie)-.11 E -.165(ve)-.275 G 2.75(st).165 G(hat the)-2.75 E
(subsequent Quick-Start data pack)100.8 631 Q
(ets from this connection will not change the current)-.11 E(under)100.8
644 Q(-utilized state of the router)-.22 E(.)-.605 E 2.75(An)100.8 670 S
(on-participating router forw)-2.75 E
(ards the Quick-Start Request unchanged, without)-.11 E
(decrementing the QS TTL.)100.8 683 Q
(The non-participating router still decrements the TTL \214eld in)5.5 E
(the IP header)100.8 696 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)100.8 709 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.)100.8 722 Q(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(3.3. [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 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF 2.75
(3.3.1. Pr)72 85 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 Quick-Start Option has\
 the Function \214eld set to "1000", then this is a Report of)100.8 111
Q(Appro)100.8 124 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)100.8 137 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)100.8 150 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)100.8 163 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)
100.8 176 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 decide to den)100.8
189 Q 2.75(yf)-.165 G(uture Quick-Start requests from this sender)-2.75
E 2.75(,i)-.44 G(ncluding, if desired,)-2.75 E
(deleting Quick-Start requests from future pack)100.8 202 Q
(ets from this sender)-.11 E 5.5(.S)-.605 G(ection 9.4.1 discusses)-5.5
E(misbeha)100.8 215 Q(ving senders in more detail.)-.22 E
(From the Report of Appro)5.5 E -.165(ve)-.165 G 2.75(dR).165 G
(ate, the router can)-2.75 E(also learn if some of the do)100.8 228 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)-2.75 E
(smaller rate, and adjust its bandwidth allocations accordingly)100.8
241 Q 5.5(.F)-.715 G(rom a Report of Appro)-5.5 E -.165(ve)-.165 G(d)
.165 E(Rate with a Rate Report of zero, the router can learn if do)100.8
254 Q(wnstream routers denied the)-.275 E(earlier Quick-Start request.)
100.8 267 Q F1(3.4.)72 306 Q/F2 13/Times-Bold@0 SF(The QS Nonce)5.5 E F0
(The QS Nonce gi)100.8 332 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)100.8 345 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)100.8 358 Q
(alue of the Rate Request \(e.g., when the sender al)-.275 E -.11(wa)
-.11 G(ys requests the same).11 E -.275(va)100.8 371 S
(lue, and the recei).275 E -.165(ve)-.275 G 2.75(rh).165 G
(as a long history of communication with that sender\).)-2.75 E -.44(Wi)
5.5 G(thout the).44 E(QS Nonce, there is nothing to pre)100.8 384 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)100.8 397 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(This v)
5.5 E(ersion of the)-.165 E
(nonce is based on a proposal from Guohan Lu [L05].)100.8 410 Q
(Initial v)5.5 E(ersions of this document)-.165 E
(contained an eight-bit QS Nonce, and subsequent v)100.8 423 Q
(ersions discussed the possibility of a)-.165 E(four)100.8 436 Q
(-bit QS Nonce.)-.22 E -.88(Ta)100.8 462 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 16])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 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(alue, using the requirements for)-.275 E
("randomness" in the pre)100.8 390 Q(vious paragraph.)-.275 E(Similarly)
5.5 E 2.75(,i)-.715 G 2.75(ft)-2.75 G
(he router reduces the Rate Request)-2.75 E
(by N steps, the router MUST set the 2N bits in the rele)100.8 403 Q
-.275(va)-.275 G(nt \214elds in the QS Nonce to a ne).275 E(w)-.275 E
(random v)100.8 416 Q 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 the sender)-2.75 E(.)
-.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 guessable 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 17])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 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(an not 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 bytes 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(The Quick-Start)5.5 E
(Request also includes random v)100.8 384 Q
(alues for the QS TTL and the QS Nonce.)-.275 E(When used for)5.5 E
(initial start-up, the Quick-Start request pack)100.8 397 Q
(et can be either the SYN or SYN/A)-.11 E(CK pack)-.44 E(et,)-.11 E
(as described abo)100.8 410 Q -.165(ve)-.165 G 5.5(.T).165 G
(he requested rate includes an estimate for the transport and IP header)
-5.5 E -.165(ove)100.8 423 S 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 the).44 E
(TCP header in the responding SYN/A)100.8 436 Q(CK pack)-.44 E(et or A)
-.11 E(CK pack)-.44 E(et, called the Quick-Start)-.11 E(response pack)
100.8 449 Q(et, informing host A of the results of their request.)-.11 E
(If the ackno)100.8 475 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)100.8 488 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)100.8 501 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')100.8 514 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)100.8 527 Q
(ault initial congestion windo)-.11 E -.715(w.)-.275 G
(If the returning pack)100.8 553 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)
100.8 566 Q(determine the Quick-Start congestion windo)100.8 579 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)100.8 592 Q(ets sent as the resu\
lt of a successful Quick-Start request, up to the time)-.11 E
(when the \214rst Quick-Start pack)100.8 605 Q(et is ackno)-.11 E 2.75
(wledged. The)-.275 F(sender sends a Report of)2.75 E(Appro)100.8 618 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 to)
2.75 E(transmit Quick-Start pack)100.8 631 Q
(ets at the rate indicated in the Quick-Start Response, at the le)-.11 E
-.165(ve)-.275 G(l).165 E(of granularity possible by the sending host.)
100.8 644 Q 1.76 -.88(We n)5.5 H
(ote that the limitations of interrupt timing).88 E(on computers can li\
mit the ability of the TCP host in rate-pacing the 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 18])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF(4.1.)
72 85 Q/F2 13/Times-Bold@0 SF(When to Use Quick-Start)5.5 E F0(In addit\
ion to the use of Quick-Start when a connection is established, there a\
re se)100.8 111 Q -.165(ve)-.275 G(ral).165 E
(additional points in a connection when a transport protocol may w)100.8
124 Q(ant to issue a Rate)-.11 E 2.75(Request. W)100.8 137 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')100.8 150 Q 2.75(sR)-.605 G
(ate Requests are not meant to be used for \214ne-grained control of)
-2.75 E(the transport')100.8 163 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)100.8 176 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.)100.8 189 Q(The follo)100.8 215 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)129.6 244.6 Q(capacity of the netw)129.6 257.6 Q
(ork, as discussed abo)-.11 E -.165(ve)-.165 G 5.5(.\().165 G 2.75(At)
-5.5 G(ransport that uses TCP Control)-2.75 E
(Block sharing, the Congestion Manager)129.6 270.6 Q 2.75(,o)-.44 G 2.75
(rt)-2.75 G(he lik)-2.75 E 2.75(em)-.11 G(ay not need Quick-Start to)
-2.75 E(determine an appropriate rate.\))129.6 283.6 Q
(\(2\) After an idle period when the transport no longer has a v)129.6
313.2 Q(alidated estimate of the)-.275 E -.22(av)129.6 326.2 S
(ailable bandwidth for this \215o)-.055 E 4.18 -.715(w. \()-.275 H(An e)
.715 E(xample could be a persistent-HTTP)-.165 E(connection when a ne)
129.6 339.2 Q 2.75(wH)-.275 G(TTP request is recei)-2.75 E -.165(ve)
-.275 G 2.75(da).165 G(fter an idle period.\))-2.75 E
(\(3\) After a host has recei)129.6 368.8 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)129.6 381.8 Q
(ork attachment.)-.11 E(This can happen due to some underlying mobility)
5.5 E(mechanism lik)129.6 394.8 Q 2.75(eM)-.11 G
(obile IP [RFC3344,RFC3775].)-2.75 E(Some transports, such as SCTP)5.5 E
([RFC2960], may associate with multiple IP addresses and can switch add\
resses \(and,)129.6 407.8 Q(therefore netw)129.6 420.8 Q
(ork paths\) in mid-connection.)-.11 E
(If the transport has concrete kno)5.5 E(wledge)-.275 E
(of a changing netw)129.6 433.8 Q
(ork path then the current sending rate may not be appropriate and)-.11
E(the transport sender may use Quick-Start to probe the netw)129.6 446.8
Q(ork to see if it can send at)-.11 E 2.75(ah)129.6 459.8 S(igher rate.)
-2.75 E(\(Alternati)5.5 E -.165(ve)-.275 G(ly).165 E 2.75(,t)-.715 G
(raditional slo)-2.75 E(w-start should be used in this case when)-.275 E
(Quick-Start is not a)129.6 472.8 Q -.275(va)-.22 G(ilable.\)).275 E(\(\
4\) After an application-limited period when the sender has been using \
only a small)129.6 502.4 Q(amount of its appropriate share of the netw)
129.6 515.4 Q(ork capacity)-.11 E 2.75(,a)-.715 G(nd has no v)-2.75 E
(alid estimate for)-.275 E(its f)129.6 528.4 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.)129.6 541.4 Q -.165
(Fo)5.5 G 2.75(ri).165 G(nstance, consider an)-2.75 E
(application that steadily e)129.6 554.4 Q(xchanges lo)-.165 E
(w-rate control messages and suddenly needs to)-.275 E(transmit a lar)
129.6 567.4 Q(ge amount of data.)-.198 E(Of the abo)100.8 597 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 \(2\).)100.8 610 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.)100.8 623 Q(Case \(3\) requires e)
5.5 E(xternal noti\214cations not presently)-.165 E
(de\214ned for TCP or other transport protocols.)100.8 636 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.)100.8 649 Q
(Case \(4\) requires further thought and in)5.5 E -.165(ve)-.44 G(stig)
.165 E(ation)-.055 E(with re)100.8 662 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)100.8 675 S
(rrant transmitting a Quick-Start Request.).11 E
(As a general guideline, a TCP sender SHOULD NO)100.8 701 Q 2.75(Ts)-.44
G(end a Quick-Start request until it)-2.75 E(has con\214rmed that is re\
ady to transmit enough data to use the requested rate o)100.8 714 Q
-.165(ve)-.165 G 2.75(rt).165 G(he)-2.75 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.1. [P)2.75 F(age 19])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E
(round-trip time of the connection \(or o)100.8 85 Q -.165(ve)-.165 G
2.75(r1).165 G(00 ms, if the round-trip time is not kno)-2.75 E 2.75
(wn\). In)-.275 F(an)100.8 98 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 request)-2.75 E
(within the most recent round-trip time.)100.8 111 Q(Section 4.6 discus\
ses some of the issues of using Quick-Start at connection initiation, a\
nd)100.8 137 Q(Section 4.7 discusses issues that arise when Quick-Start\
 is used to request a lar)100.8 150 Q(ger sending)-.198 E
(rate after an idle period.)100.8 163 Q/F1 11/Times-Bold@0 SF(4.2.)72
202 Q/F2 13/Times-Bold@0 SF
(The Quick-Start Response Option in the TCP header)5.5 E F0
(In order to appro)100.8 228 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)100.8 241 Q
(in the TCP header)100.8 254 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)107.4 299 S 6.6
(01234567890123456789012345678901)107.4 312 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
325 Q 33(|K)100.8 338 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
351 S 92.4(|Request| |)-52.8 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
364 Q 125.4(|Q)100.8 377 S 6.6(SN)-125.4 G 204.6(once |)-6.6 F(|)19.8 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)100.8
390 Q(Figure 5.)120.6 416 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)100.8 448 Q(TCP option \(to be assigned by IAN)100.8 461 Q
(A\).)-.385 E(The second byte of the Quick-Start Response option contai\
ns the option length in bytes.)100.8 487 Q
(The length \214eld MUST be set to four bytes.)100.8 500 Q
(The third byte of the Quick-Start Response option contains a four)100.8
526 Q(-bit Reserv)-.22 E(ed \214eld, and)-.165 E(the four)100.8 539 Q
(-bit allo)-.22 E
(wed Rate Request, formatted as in the Quick-Start option.)-.275 E
(The fourth byte of the TCP option contains the TTL Dif)100.8 565 Q 2.75
(f. The)-.275 F(TTL Dif)2.75 E 2.75(fc)-.275 G(ontains the)-2.75 E(dif)
100.8 578 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)
100.8 591 Q(et, as calculated in equations \(1\) or \(2\) \(depending o\
n whether IPv4 or IPv6 is used\).)-.11 E(The last four bytes of the TCP\
 option contain the 30-bit QS Nonce and a tw)100.8 617 Q(o-bit Reserv)
-.11 E(ed)-.165 E(\214eld.)100.8 630 Q 1.76 -.88(We n)100.8 656 T(ote t\
hat the Quick-Start Response Option for TCP contains eight bytes, and t\
he length).88 E
(of the TCP option \214eld is generally at most 40 bytes.)100.8 669 Q
(Other TCP options that might be)5.5 E(used include T)100.8 682 Q
(ime Stamp \(ten bytes\), W)-.385 E(indo)-.44 E 2.75(wS)-.275 G
(cale \(three bytes\), Maximum Se)-2.75 E(gment Size)-.165 E
(\(four bytes\), Selecti)100.8 695 Q .33 -.165(ve A)-.275 H(ckno).165 E
(wledgments Data \(at least ten bytes\), and Selecti)-.275 E -.165(ve)
-.275 G(Ackno)100.8 708 Q(wledgments Permitted \(tw)-.275 E 2.75(ob)-.11
G(ytes\).)-2.75 E(Flo)72 769 Q 204.025(yd/Allman/Jain/Sarolahti Section)
-.11 F 2.75(4.2. [P)2.75 F(age 20])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF(4.3.)
72 85 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)100.8 111 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)100.8 124 Q
(alue in the IP TTL \214eld, to the recei)-.275 E(ving TCP)-.275 E
(layer)100.8 137 Q(.)-.605 E(If the TCP host is willing to permit the Q\
uick-Start Request, then a Quick-Start Response)100.8 163 Q
(option is included in the TCP header of the corresponding ackno)100.8
176 Q(wledgement pack)-.275 E 2.75(et. The)-.11 F
(Rate Request in the Quick-Start Response option is set to the recei)
100.8 189 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)100.8 202 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)100.8 215 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
228 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
(\(depending on whether IPv4 or IPv6 is used\).)100.8 241 Q
(The QS Nonce in the Response is set to the)5.5 E(recei)100.8 254 Q
-.165(ve)-.275 G 2.75(dv).165 G
(alue of the QS Nonce in the Quick-Start option.)-3.025 E
(The Quick-Start Response will NO)100.8 280 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 is an)-.11 E(indication of congestion on the return path, in \
which case it is better not to appro)100.8 293 Q .33 -.165(ve t)-.165 H
(he).165 E(Quick-Start Request.)100.8 306 Q F1(4.4.)72 345 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)100.8 371 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)100.8 384 Q
(wledgement \214rst checks that the Quick-Start Response is v)-.275 E
2.75(alid. The)-.275 F(Quick-Start Response is v)100.8 397 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)100.8 410 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)100.8 423 Q -.165(ve)-.275 G 2.75(dR).165 G
(ate Request is K, then the 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.)
100.8 436 Q(If these checks are)5.5 E
(not successful, then the Quick-Start request f)100.8 449 Q
(ailed, and the TCP host MUST use the def)-.11 E(ault)-.11 E
(TCP congestion windo)100.8 462 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)100.8 475 Q
(Request, for a recei)100.8 488 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.)100.8 501 Q
(Whether the Quick-Start request)5.5 E -.11(wa)100.8 514 S 2.75(ss).11 G
(uccessful or not, the TCP host MUST send a Report of Appro)-2.75 E
-.165(ve)-.165 G 2.75(dR).165 G(ate.)-2.75 E
(If the checks of the TTL Dif)100.8 540 Q 2.75(fa)-.275 G
(nd the Rate Request are successful, then the TCP host sets)-2.75 E
(its Quick-Start congestion windo)100.8 553 Q 2.75(w\()-.275 G
(in terms of MSS-sized se)-2.75 E(gments\), QS-cwnd, as)-.165 E(follo)
100.8 566 Q(ws:)-.275 E(QS-cwnd = \(R * T\) / \(MSS + H\))100.8 592 Q
(\(3\))88 E(where R the Rate Request in bytes per second, T the measure\
d round-trip time in seconds,)100.8 618 Q
(and H the estimated TCP/IP header size in bytes \(e.g., 40 bytes\).)
100.8 631 Q(Deri)100.8 657 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)100.8 670 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.)100.8 683 Q
(The TCP host SHOULD set its congestion windo)100.8 709 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.)100.8 722 Q
(When Quick-Start is used at the)5.5 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.4. [P)2.75 F(age 21])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E(be)100.8 85 Q
(ginning of a connection, before an)-.165 E 2.75(yp)-.165 G(ack)-2.75 E
(et marks or losses ha)-.11 E .33 -.165(ve b)-.22 H
(een reported, the TCP).165 E(host MA)100.8 98 Q 2.75(Yu)-1.155 G
(se the reported Rate Request to set the slo)-2.75 E
(w-start threshold to a desired v)-.275 E(alue,)-.275 E
(e.g., to some small multiple of the congestion windo)100.8 111 Q 4.18
-.715(w. \()-.275 H(The initial v).715 E(alue of ssthresh is)-.275 E
(allo)100.8 124 Q(wed to be arbitrarily high, and some TCP implementati\
ons use the size of the)-.275 E(adv)100.8 137 Q(ertised windo)-.165 E
2.75(wf)-.275 G(or ssthresh [RFC2581].\))-2.75 E(If QS-cwnd is used, th\
e TCP host sets a \215ag that it is in Quick-Start mode, and while in)
100.8 163 Q(Quick-Start mode the TCP sender MUST use rate-based pacing \
to pace out Quick-Start)100.8 176 Q(pack)100.8 189 Q
(ets at the speci\214ed Rate Request.)-.11 E
(If, during Quick-Start mode, the TCP sender)5.5 E(recei)100.8 202 Q
-.165(ve)-.275 G 2.75(sA).165 G(CKs for pack)-3.19 E
(ets sent before this Quick-Start mode w)-.11 E(as entered, these A)-.11
E(CKs are)-.44 E(processed as usual, follo)100.8 215 Q(wing the def)
-.275 E(ault congestion control mechanisms.)-.11 E(Quick-Start)5.5 E
(mode ends when the TCP host recei)100.8 228 Q -.165(ve)-.275 G 2.75(sa)
.165 G 2.75(nA)-2.75 G(CK for one of the Quick-Start pack)-3.19 E(ets.)
-.11 E(If the congestion windo)100.8 254 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)100.8 267 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)100.8 280 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')100.8 293 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\
ckStart option, or because of)100.8 306 Q(delays at the recei)100.8 319
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)100.8 332 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)100.8 345 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)100.8 358 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)100.8 371 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)100.8 384 Q(CK for a Quick-Start pack)
-.44 E(et, the sender reduces its congestion windo)-.11 E 2.75(wt)-.275
G 2.75(ot)-2.75 G(he)-2.75 E(amount that has actually been used.)100.8
397 Q(As an e)100.8 423 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)100.8 436 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)100.8 449 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)100.8 462 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)100.8 475 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)100.8 488 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)100.8 501 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(R*T/\(B*2\) pack)100.8 514 Q
(ets, the actual number of pack)-.11 E
(ets that were needed to \214ll the pipe at a)-.11 E
(sending rate of R KBps.)100.8 527 Q(After Quick-Start mode is e)100.8
553 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
(sender returns to using the def)100.8 566 Q
(ault congestion control mechanisms, processing further)-.11 E
(incoming A)100.8 579 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)100.8 592 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)100.8 605 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)100.8 618 S
(iting Quick-Start mode, as allo).165 E(wed by ssthresh.)-.275 E 1.76
-.88(To a)100.8 644 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)100.8 657 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)100.8 670 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(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(4.4. [P)2.75 F(age 22])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF(4.5.)
72 85 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)100.8 111 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)100.8 124 Q(wing a successful Quick-Start request.)
-.275 E(After detecting the loss of a)5.5 E(Quick-Start pack)100.8 137 Q
(et, TCP MUST re)-.11 E -.165(ve)-.275 G(rt to the def).165 E
(ault congestion control procedures that)-.11 E -.11(wo)100.8 150 S
(uld 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 2.75(d. F).165 F(or e)-.165 E(xample, if)-.165 E
(Quick-Start is used for setting the initial windo)100.8 163 Q 1.43
-.715(w, a)-.275 H(nd a pack).715 E(et from the initial windo)-.11 E
2.75(wi)-.275 G(s)-2.75 E(lost, then the TCP sender MUST then slo)100.8
176 Q(w-start with the def)-.275 E(ault initial windo)-.11 E 2.75(wt)
-.275 G(hat w)-2.75 E(ould)-.11 E(ha)100.8 189 Q .33 -.165(ve b)-.22 H
(een used if Quick-Start had not been used.).165 E(In addition to re)5.5
E -.165(ve)-.275 G(rting to the def).165 E(ault)-.11 E
(congestion control mechanisms, the sender MUST tak)100.8 202 Q 2.75(ei)
-.11 G(nto account that the Quick-Start)-2.75 E(congestion windo)100.8
215 Q 2.75(ww)-.275 G(as too lar)-2.86 E 2.75(ge. Thus,)-.198 F
(the sender SHOULD decrease ssthresh to at most)2.75 E
(half the number of Quick-Start pack)100.8 228 Q
(ets that were successfully transmitted.)-.11 E(Section A.5)5.5 E
(discusses possible alternati)100.8 241 Q -.165(ve)-.275 G 2.75(si).165
G 2.75(nr)-2.75 G(esponding to the loss of a Quick-Start pack)-2.75 E
(et.)-.11 E 1.76 -.88(We n)100.8 267 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')100.8 280 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)100.8 293 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)100.8 306 Q(ets mark)-.11
E(ed as e)-.11 E(xperiencing congestion.)-.165 E F1(4.6.)72 345 Q F2
(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 issues of using Quick-Start are \
related to the speci\214c scenario in which Quick-)100.8 371 Q
(Start is used.)100.8 384 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)100.8 397 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
410 Q(ets that are discarded by middlebox)-.11 E(es.)-.165 E F1 2.75
(4.6.1. Interactions)72 449 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)100.8 475 Q
(ge initial windo)-.198 E 2.75(wc)-.275 G(oncerns the)-2.75 E
(interactions between the lar)100.8 488 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:)
100.8 501 Q("When lar)129.6 517.6 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)129.6 530.6 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)129.6 543.6 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)129.6 556.6 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)100.8 573.2 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 \(e.g., from a PMTUD)-2.75 E(cache or from some other IETF-appro)
100.8 586.2 Q -.165(ve)-.165 G 2.75(dm).165 G
(ethod\), then the sender should use that MTU)-2.75 E(for se)100.8 599.2
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 kno)-2.75 E 2.75(wt)-.275 G(he)-2.75 E -.165(Pa)100.8
612.2 S(th 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 should be)
-2.75 E(conserv)100.8 625.2 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 pack)-.198 E
(ets with)-.11 E(the DF bit set is not desirable, b)100.8 638.2 Q
(ut sending a lar)-.22 E(ge number of pack)-.198 E
(ets that are fragmented in)-.11 E(the netw)100.8 651.2 Q
(ork can be equally undesirable.)-.11 E(The sender SHOULD send one lar)
100.8 677.2 Q(ge pack)-.198 E(et in the initial windo)-.11 E 2.75(ww)
-.275 G(ith the DF bit set, and)-2.75 E(send the remaining pack)100.8
690.2 Q(ets in the initial windo)-.11 E 2.75(ww)-.275 G
(ith a smaller MTU of 576 bytes \(or 1280)-2.75 E(bytes with IPv6\).)
100.8 703.2 Q(Flo)72 769 Q 195.775(yd/Allman/Jain/Sarolahti Section)-.11
F 2.75(4.6.1. [P)2.75 F(age 23])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E 2.75(As)100.8 85 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 98 Q 2.75(wo)-.275 G 2.75(fd)-2.75 G(ata while)-2.75
E(also doing P)100.8 111 Q(ath MTU Disco)-.165 E -.165(ve)-.165 G(ry)
.165 E(.)-.715 E/F1 11/Times-Bold@0 SF 2.75(4.6.2. Quick-Start)72 163 R
(Request P)2.75 E(ack)-.11 E(ets that ar)-.11 E 2.75(eD)-.198 G
(iscarded by Middleboxes)-2.75 E F0(It is al)100.8 189 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)
100.8 202 Q(ork due to congestion, or to be block)-.11 E
(ed due to interactions with middlebox)-.11 E(es,)-.165 E
(where a middlebox is de\214ned as an)100.8 215 Q 2.75(yi)-.165 G
(ntermediary box performing functions apart from)-2.75 E(normal, standa\
rd functions of an IP router on the data path between a source host and)
100.8 228 Q(destination host [RFC3234].)100.8 241 Q
(Measurement studies of interactions between transport)5.5 E
(protocols and middlebox)100.8 254 Q(es [MAF04] sho)-.165 E 2.75(wt)
-.275 G(hat for 70% of the web serv)-2.75 E(ers in)-.165 E -.165(ve)-.44
G(stig).165 E(ated, no)-.055 E
(connection is established if the TCP SYN pack)100.8 267 Q
(et contains an unkno)-.11 E(wn IP option \(and for)-.275 E
(43% of the web serv)100.8 280 Q
(ers, no connection is established if the TCP SYN pack)-.165 E
(et contains an IP)-.11 E -.385(Ti)100.8 293 S(meStamp Option\).).385 E
(In both cases, this is presumably due to middlebox)5.5 E
(es along that path.)-.165 E(If the TCP sender doesn')100.8 319 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)100.8 332 Q(CK)-.44 E(pack)100.8 345 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
358 Q(CK pack)-.44 E(et containing the Quick-Start Request, then the)
-.11 E(TCP sender SHOULD resend the SYN or SYN/A)100.8 371 Q(CK pack)
-.44 E(et without the Quick-Start)-.11 E(Request [RFC3360].)100.8 384 Q
(RFC 1122 and 2988 recommend that the sender should set the initial R)
100.8 410 Q .396 -.198(TO t)-.66 H 2.75(ot).198 G(hree seconds,)-2.75 E
(though man)100.8 423 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)100.8 436 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.)100.8 449 Q(In the case of a retransmission, in additio\
n to resending the SYN or SYN/A)100.8 475 Q(CK pack)-.44 E(et)-.11 E
(without the Quick-Start Request, the TCP sender SHOULD use an R)100.8
488 Q .396 -.198(TO o)-.66 H 2.75(ft).198 G(hree seconds)-2.75 E
(and a dif)100.8 501 Q(ferent Initial Sequence Number)-.275 E 5.5(.U)
-.605 G(sing this scheme the TCP sender MUST k)-5.5 E(eep)-.11 E
(track of when each of the SYN \(or SYN/A)100.8 514 Q(CK\) pack)-.44 E
(ets w)-.11 E(as transmitted.)-.11 E(In this w)5.5 E(ay)-.11 E 2.75(,a)
-.715 G(n)-2.75 E(ackno)100.8 527 Q
(wledgement for the retransmitted SYN or SYN/A)-.275 E(CK pack)-.44 E
(et can be matched with the)-.11 E(SYN or SYN/A)100.8 540 Q
(CK being ackno)-.44 E
(wledged, and the transmission time of the SYN \(or)-.275 E(SYN/A)100.8
553 Q(CK\) being ackno)-.44 E(wledged can be used for an R)-.275 E
(TT measurement to seed the R)-.66 E -.198(TO)-.66 G 5.5(.I).198 G(f)
-5.5 E(only the retransmitted SYN or SYN/A)100.8 566 Q(CK is ackno)-.44
E(wledged, the TCP sender can reasonably)-.275 E
(assume that the earlier SYN or SYN/A)100.8 579 Q
(CK with the Quick-Start option w)-.44 E(as dropped by the)-.11 E(netw)
100.8 592 Q(ork because of the option and not because of congestion.)
-.11 E(In this case, the TCP sender)5.5 E
(can refrain from performing TCP')100.8 605 Q 2.75(ss)-.605 G
(tandard congestion control state changes.)-2.75 E 1.76 -.88(We n)100.8
631 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)100.8 644 Q
(gotiate ECN-capability with the)-.165 E
(TCP host at the other end, then the drop of a TCP SYN pack)100.8 657 Q
(et could be due to congestion,)-.11 E(to a middlebox dropping the pack)
100.8 670 Q(et because of the IP Option, or because of a middlebox)-.11
E(dropping the pack)100.8 683 Q
(et because of the information in the TCP header ne)-.11 E
(gotiating ECN.)-.165 E(In this)5.5 E
(case, the sender could resend the dropped pack)100.8 696 Q
(et without either the Quick-Start or the ECN)-.11 E 2.75
(requests. Alternately)100.8 709 R 2.75(,t)-.715 G
(he sender could resend the dropped pack)-2.75 E(et with only the ECN)
-.11 E(request in the TCP header)100.8 722 Q 2.75(,r)-.44 G
(esending the TCP SYN pack)-2.75 E(et without either the Quick-Start)
-.11 E(Flo)72 769 Q 195.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(4.6.2. [P)2.75 F(age 24])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E
(or the ECN requests if the second TCP SYN pack)100.8 85 Q
(et is dropped.)-.11 E(The second choice seems)5.5 E(reasonable, gi)
100.8 98 Q -.165(ve)-.275 G 2.75(nt).165 G(hat a TCP SYN pack)-2.75 E
(et today is more lik)-.11 E(ely to be block)-.11 E(ed due to IP)-.11 E
(Options than due to an ECN request in the TCP header [MAF04].)100.8 111
Q(It is al)100.8 137 Q -.11(wa)-.11 G
(ys possible that some middlebox that doesn').11 E 2.75(td)-.198 G
(rop TCP SYN pack)-2.75 E(ets containing)-.11 E
(Quick-Start options will still drop or delay TCP data pack)100.8 150 Q
(ets containing Quick-Start)-.11 E(options as Appro)100.8 163 Q -.165
(ve)-.165 G 2.75(dR).165 G(ate reports.)-2.75 E(This w)5.5 E
(ould be one reason for a TCP sender to report the)-.11 E(Appro)100.8
176 Q -.165(ve)-.165 G 2.75(dR).165 G(ate in a separate control pack)
-2.75 E(et, rather than in a data pack)-.11 E(et.)-.11 E/F1 11
/Times-Bold@0 SF(4.7.)72 215 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)100.8 241 Q
(wing issues that arise when Quick-Start is used by TCP to)-.275 E
(request a lar)100.8 254 Q(ger windo)-.198 E 2.75(wi)-.275 G 2.75(nt)
-2.75 G(he middle of connection, for e)-2.75 E
(xample after an idle period: \(1\))-.165 E(determining the rate to req\
uest; and \(2\) the response if Quick-Start pack)100.8 267 Q
(ets are dropped;)-.11 E(\(1\) Determining the rate to request:)100.8
293 Q(In the middle of connection, an easy rule of thumb w)100.8 306 Q
(ould be for the TCP sender to)-.11 E(determine the lar)100.8 319 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)-2.75 E(pack)100.8 332 Q
(et drop, to translate this congestion windo)-.11 E 2.75(wt)-.275 G 2.75
(oas)-2.75 G(ending rate, and use this rate in the)-2.75 E
(Quick-Start request.)100.8 345 Q(If the request is granted, then the s\
ender essentially restarts with its)5.5 E(old congestion windo)100.8 358
Q 2.75(wf)-.275 G(rom before it w)-2.75 E(as reduced, for e)-.11 E
(xample during an idle period.)-.165 E
(In the case of an idle period, the sender SHOULD NO)100.8 384 Q 2.75
(Tu)-.44 G(se Quick-Start if the idle period)-2.75 E
(has been less than an R)100.8 397 Q -.198(TO)-.66 G 2.75(,a).198 G
(nd the congestion windo)-2.75 E 2.75(wh)-.275 G(as not decayed do)-2.75
E(wn to less than)-.275 E(half of its v)100.8 410 Q
(alue at the start of the idle period.)-.275 E
(Such a use of Quick-Start requires further)5.5 E(in)100.8 423 Q -.165
(ve)-.44 G(stig).165 E(ation.)-.055 E 2.75(AQ)100.8 449 S(uick-Start Re\
quest sent in the middle of a TCP connection could be carried either in\
 a)-2.75 E(data pack)100.8 462 Q(et or in a pure ackno)-.11 E
(wledgement pack)-.275 E(et.)-.11 E(\(2\) Response if Quick-Start pack)
100.8 488 Q(ets are dropped:)-.11 E(If Quick-Start pack)100.8 501 Q
(ets are dropped in the middle of connection, then the sender MUST)-.11
E(re)100.8 514 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)100.8 527 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(4.8.)72 566 Q F2
(An Example Quick-Start Scenario with TCP)5.5 E F0(The follo)100.8 592 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)100.8 605 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.)100.8 618 Q 2.75(*T)100.8 644 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)100.8 670 S(outers along the forw)-2.75 E
(ard path modify the Quick-Start Request as appropriate.)-.11 E 2.75(*H)
100.8 696 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
709 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)100.8 722 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(Flo)72 769 Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F
2.75(4.8. [P)2.75 F(age 25])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(IP header of the SYN/A)100.8
85 Q(CK pack)-.44 E(et.)-.11 E 2.75(*R)100.8 111 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)
100.8 137 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)100.8 150 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)100.8 163 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)
100.8 176 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)100.8 189 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)100.8 215
Q 2.75(ff)-.275 G(or the Quick-Start Request in the incoming)-2.75 E
(SYN/A)100.8 228 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)100.8 241 Q(et.)-.11 E 2.75(*H)100.8 267 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)100.8 280 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)100.8 293 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)
100.8 306 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)100.8 319 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 11/Times-Bold@0
SF(5.)72 358 Q/F2 14/Times-Bold@0 SF(Quick-Start and IPsec AH)5.5 E F0
(This section sho)100.8 384 Q(ws that Quick-Start is compatible with IP\
sec AH \(Authentication Header\).)-.275 E(AH uses an Inte)100.8 397 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)100.8 410 Q
(grity [RFC2402,2402bis].)-.165 E(Changes to the Quick-Start)5.5 E
(option in the IP header do not af)100.8 423 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
436 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.)100.8 449 Q(Because the contents of the Q\
uick-Start option can change along the path, it is important)100.8 475 Q
(that these changes not af)100.8 488 Q
(fect the IPsec Authentication Header Inte)-.275 E(grity Check V)-.165 E
(alue \(AH)-1.221 E 2.75(ICV\). F)100.8 501 R(or IPv4, RFC 2402 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)100.8 514 Q(problems with e)100.8 527 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)100.8 540 Q
(for AH ICV calculation purposes.)100.8 553 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)100.8 566 Q
(A-allocated option type has the v)-.385 E(alue)-.275 E 2.75(1t)100.8
579 S 2.75(oi)-2.75 G
(ndicate that the Quick-Start option data can change en route.)-2.75 E
(RFC 2402 requires that)5.5 E(the option data of an)100.8 592 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)100.8 605
Q(fect the calculation of the AH)-.275 E(ICV)100.8 618 Q(.)-1.419 E F1
(6.)72 657 Q F2(Quick-Start in IP T)5.5 E(unnels)-1.288 E F0(This secti\
on considers interactions between Quick-Start and IP tunnels, including\
 IPsec)100.8 683 Q([RFC2401,2401bis] and IP in IP [RFC2003].)100.8 696 Q
(In the discussion, we use TTL Dif)100.8 722 Q
(f, de\214ned earlier as the dif)-.275 E(ference between the IP TTL)
-.275 E(Flo)72 769 Q 212.275(yd/Allman/Jain/Sarolahti Section)-.11 F
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(September 2006)2.75 E(March 2006)106.935 E
(and the Quick-Start TTL, mod 256.)100.8 85 Q
(Recall that the sender considers the Quick-Start)5.5 E(request appro)
100.8 98 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)100.8 111 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)
100.8 137 Q 2.75(w")-.275 G(outer" IP header)-2.75 E(that encapsulates \
the original or "inner" IP header and its associated pack)100.8 150 Q
2.75(et. In)-.11 F(man)2.75 E 2.75(yc)-.165 G(ases,)-2.75 E(the ne)100.8
163 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)-2.75 E(connection, enabling the netw)100.8
176 Q(ork to establish a tunnel without requiring endpoint)-.11 E 2.75
(participation. W)100.8 189 R 2.75(ed)-.88 G(enote tunnels that specify\
 that the outer header be discarded at tunnel)-2.75 E -.165(eg)100.8 202
S(ress as "simple tunnels", and we denote tunnels where the e).165 E
(gress sa)-.165 E -.165(ve)-.22 G 2.75(sa).165 G(nd uses)-2.75 E(inform\
ation from the outer header before discarding it as "non-simple tunnels\
".)100.8 215 Q(An)5.5 E -.165(ex)100.8 228 S
(ample of a "non-simple tunnel" w).165 E
(ould be a tunnel con\214gured to support ECN, where the)-.11 E -.165
(eg)100.8 241 S(ress router might cop).165 E 2.75(yt)-.11 G
(he ECN codepoint in the outer header to the inner header before)-2.75 E
(discarding the outer header [RFC3168].)100.8 254 Q/F1 11/Courier@0 SF
(__ Tunnels Compatible with Quick-Start)232.8 286 Q(/)226.2 299 Q
(Simple Tunnels)100.8 312 Q(__/)13.2 E(\\)219.6 325 Q
(\\__ Tunnels Not Compatible with Quick-Start)226.2 338 Q
(\(False Positives!\))318.6 351 Q(__ Tunnels Supporting Quick-Start)
259.2 390 Q(/)252.6 403 Q(/)246 416 Q
(Non-Simple Tunnels __/_____ Tunnels Compatible with Quick-Start,)100.8
429 Q 66(\\b)239.4 442 S(ut Not Supporting Quick-Start)-66 E(\\)246 455
Q(\\__ Tunnels Not Compatible with Quick-Start?)252.6 468 Q
(Figure 6: Categories of Tunnels.)100.8 494 Q F0 -.495(Tu)100.8 526 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)100.8 539 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)100.8 552 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
565 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
578 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)100.8 604
Q(arding before tunnel)-.11 E(encapsulation tak)100.8 617 Q
(es place, then the simple tunnel is compatible with Quick-Start, with)
-.11 E(Quick-Start requests being rejected.)100.8 630 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.)100.8 643 Q(There ar\
e some simple tunnels that are not compatible with Quick-Start, allo)
100.8 669 Q(wing `f)-.275 E(alse)-.11 E(positi)100.8 682 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)
100.8 695 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)100.8 721 Q -.165(ve)-.44
G(stig).165 E(ate the occurrence of tunnels that are not)-.055 E(Flo)72
769 Q 212.275(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(6. [P)2.75 F
(age 27])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E
(compatible with Quick-Start, and to track the e)100.8 85 Q
(xtent to which such tunnels are modi\214ed)-.165 E -.165(ove)100.8 98 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)100.8 111 Q
(fect the progression of Quick-Start from Experimental)-.275 E
(to Proposed Standard, and will af)100.8 124 Q(fect the de)-.275 E
(gree of deplo)-.165 E(yment of Quick-Start while in)-.11 E
(Experimental mode.)100.8 137 Q -.495(Tu)100.8 163 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
176 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.)100.8 189
Q(Some tunnels)5.5 E(that are compatible with Quick-Start support Quick\
-Start, while others do not.)100.8 202 Q 1.76 -.88(We n)5.5 H(ote).88 E
(that a simple tunnel is not able to support Quick-Start.)100.8 215 Q
(From a security point of vie)100.8 241 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)100.8 254 Q
(ersary could tamper with the Quick-Start)-.165 E
(information that propag)100.8 267 Q(ates be)-.055 E
(yond the tunnel endpoint, or because the Quick-Start Option)-.165 E
-.165(ex)100.8 280 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.)100.8 293 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)100.8 306 Q(Quick-Start option or zero the Quick-Start rate re\
quest and QS TTL \214elds before)100.8 319 Q 2.75(encapsulation. The)
100.8 332 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.)100.8 345 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
358 Q(ut does not support Quick-)-.22 E
(Start, where all Quick-Start requests along the path will be rejected.)
100.8 371 Q(The second approach)5.5 E(is a Quick-Start-capable mode, de\
scribed in Section 6.3, where the tunnel acti)100.8 384 Q -.165(ve)-.275
G(ly supports).165 E(Quick-Start.)100.8 397 Q/F1 11/Times-Bold@0 SF
(6.1.)72 436 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)100.8 462 Q
(ays that a simple tunnel can be compatible with Quick-Start)-.11 E -.22
(bu)100.8 475 S 2.75(tn).22 G(ot support Quick-Start, resulting in the \
rejection of all Quick-Start requests that)-2.75 E(tra)100.8 488 Q -.165
(ve)-.22 G(rse the tunnel.).165 E
(If the tunnel ingress for the simple tunnel is at a router)100.8 514 Q
2.75(,t)-.44 G(he IP TTL of the inner header is)-2.75 E
(generally decremented during forw)100.8 527 Q
(arding before tunnel encapsulation tak)-.11 E(es place.)-.11 E(In this)
5.5 E(case TTL Dif)100.8 540 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
553 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)100.8 566 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)100.8 579 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)100.8 592 Q
(.)-.605 E F1 2.75(6.1.1. Simple)72 631 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)100.8 657 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)100.8 670 Q
(\214elds or remo)100.8 683 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
696 Q(ant to support Quick-Start.)-.11 E(Deleting the Quick-Start optio\
n or zeroing the Quick-Start rate request *after)100.8 722 Q(Flo)72 769
Q 195.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(6.1.1. [P)2.75 F
(age 28])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(decapsulation* also serv)
100.8 85 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 98 Q
(If the outer header does not contain a Quick-Start Request, a)5.5 E
(Quick-Start-a)100.8 111 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)100.8 124 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)100.8 150 Q
(prior to encapsulation, and neither tunnel endpoint is a)100.8 163 Q
-.11(wa)-.165 G(re of Quick-Start, then this allo).11 E(ws)-.275 E -.11
(fa)100.8 176 S(lse positi).11 E -.165(ve)-.275 G
(s, described in the section belo).165 E -.715(w.)-.275 G/F1 11
/Times-Bold@0 SF(6.2.)72 215 Q/F2 13/Times-Bold@0 SF(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 implementation that does not support Quic\
k-Start is independent of the)100.8 254 Q
(TCP sender or a router implementation that supports Quick-Start.)100.8
267 Q(In these cases it is)5.5 E
(possible that a Quick-Start Request gets erroneously appro)100.8 280 Q
-.165(ve)-.165 G 2.75(dw).165 G(ithout the routers in the)-2.75 E
(tunnel ha)100.8 293 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)100.8 319 Q(arding, it is)-.11 E
(possible that a pack)100.8 332 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)100.8 345 Q(encapsulation tak)100.8 358 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)100.8 371 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)100.8 384 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)100.8 397 Q(ould be)-.11 E -.11(fa)100.8
410 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)100.8 423 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)100.8 436 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)100.8 449 Q(ork dri)-.11 E -.165
(ve)-.275 G(rs).165 E(and the TCP/IP protocol stack [RFC2401].)100.8 462
Q(As one e)100.8 488 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)100.8 501 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)100.8 514 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.)100.8 527 Q
(Because most VPN clients are reported to use BITS)5.5 E
([H05], we will e)100.8 540 Q(xplore this in more detail.)-.165 E 2.75
(AB)100.8 566 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)100.8 579 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 [RFC2401].)100.8 592 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)100.8 605 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)100.8 618 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.)100.8 631 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)100.8 644 Q
(et is passed from the host to)-.11 E(the BITW)100.8 657 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
683 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)100.8 696 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].)100.8 709 Q(Flo)72 769
Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(6.2. [P)2.75 F
(age 29])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(Section 9.2 discusses the r\
elated issue of non-IP queues, such as layer)100.8 85 Q(-tw)-.22 E 2.75
(oE)-.11 G(thernet or)-2.75 E -1.221(AT)100.8 98 S 2.75(Mn)1.221 G(etw)
-2.75 E(orks, as another instance of possible bottlenecks that do not p\
articipate in the)-.11 E(Quick-Start feedback.)100.8 111 Q/F1 11
/Times-Bold@0 SF(6.3.)72 150 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.)
100.8 176 Q(If the tunnel ingress node chooses to locally appro)100.8
202 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)100.8 215 Q(TTL, and MUST cop)100.8 228 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)100.8 241 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)100.8 254 Q(tunnel e)100.8 267 Q
(gress does not support Quick-Start.)-.165 E
(If the tunnel ingress node does not choose to locally appro)100.8 293 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,)100.8 306 Q
(or zero the QS TTL and the Rate Request \214elds before encapsulation.)
100.8 319 Q(Upon decapsulation, if the outer header contains a Quick-St\
art option, the tunnel e)100.8 345 Q(gress)-.165 E(MUST cop)100.8 358 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)100.8 371 Q(.)-.605 E
(IPsec uses the IKE \(Internet K)100.8 397 Q .33 -.165(ey E)-.275 H
(xchange\) 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)100.8 410 Q 2.75(document. No)
100.8 423 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)100.8 436 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)100.8 449 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.)
100.8 462 Q(This w)5.5 E
(as done for ECN for IPsec tunnels, with IKEv1 [RFC3168,)-.11 E
(Section 9.2].)100.8 475 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.)100.8 488 Q
(This document will also include a discussion of the potential)5.5 E(ef)
100.8 501 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)100.8 514 Q
(xposing the Quick-Start rate request to)-.165 E(netw)100.8 527 Q
(ork scanners.)-.11 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 30])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 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 Appro)5.5 E -.165(ve)-.165 G(d).165 E 2.75
(Rate. The)100.8 176 R(sender starts sending Quick-Start pack)2.75 E
(ets, rate-paced out at the appro)-.11 E -.165(ve)-.165 G(d).165 E
(sending rate.)100.8 189 Q 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 [SAF05], 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([SAF05] 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 -.165(Fo)5.5 G(llo).165 E(wing)-.275 E
(Section 4.1, the sender SHOULD NO)100.8 644 Q 2.75(Tr)-.44 G
(equest a sending rate lar)-2.75 E(ger than it is able to use)-.198 E
-.165(ove)100.8 657 S 2.75(rt).165 G
(he round-trip time of the connection \(or o)-2.75 E -.165(ve)-.165 G
2.75(r1).165 G(00 ms, if the round-trip time is not)-2.75 E(kno)100.8
670 Q(wn\), e)-.275 E
(xcept as required to round up the desired sending rate to the ne)-.165
E(xt-highest)-.165 E(allo)100.8 683 Q -.11(wa)-.275 G(ble request.).11 E
(Flo)72 769 Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(8.1. [P)2.75 F(age 31])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF(8.2.)
72 85 Q/F2 13/Times-Bold@0 SF(Deciding the P)5.5 E
(ermitted Rate Request at a Router)-.26 E F0
(In this section we brie\215y outline ho)100.8 111 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.)100.8 124 Q(The router should ask the follo)5.5 E
(wing questions:)-.275 E 2.75(*H)100.8 150 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)100.8 176 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)
100.8 189 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)100.8 215 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)100.8 228 Q .33 -.165(ve d)-.275 H(ue to)
.165 E(recently-appro)100.8 241 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>100.8 254 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.)100.8 267 Q 2.75(As)100.8 293 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
306 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)100.8 319 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)100.8 332 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
345 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)100.8 358 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.)100.8 371 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 D, and more)-2.75 E
(discussion of these issues is a)100.8 384 Q -.275(va)-.22 G
(ilable in [SAF05].\)).275 E 2.75(*I)100.8 410 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
423 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)
100.8 436 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)100.8 462 Q(requests at routers.)100.8 475 Q
([SAF05] discusses the range of possible Quick-Start algorithms at the)
5.5 E(router for deciding whether to appro)100.8 488 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\
AF05] also discusses Extreme Quick-Start)100.8 501 Q
(mechanisms at routers, where the router w)100.8 514 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.)100.8 527 Q F1
(9.)72 566 Q/F3 14/Times-Bold@0 SF(Ev)5.5 E(aluation of Quick-Start)-.14
E F1(9.1.)72 605 Q F2(Bene\214ts of Quick-Start)5.5 E F0
(The main bene\214t of Quick-Start is the f)100.8 631 Q
(aster start-up for the transport connection itself.)-.11 E -.165(Fo)5.5
G(r).165 E 2.75(as)100.8 644 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
657 Q 2.75(or)-.11 G(ound-trip times \(including)-2.75 E
(the round-trip time for connection establishment\).)100.8 670 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)100.8 683 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)100.8 696 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)100.8 709 Q
(ut it might eliminate or at least shorten the start-up phase.)-.22 E
(Ho)100.8 722 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(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.1. [P)2.75 F(age 32])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(could possibly allo)100.8 85
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 \(after the initial round-trip time for the SYN e)100.8 98 Q
(xchange\), instead of the log_2\(M\)-2)-.165 E
(round-trip times that it w)100.8 111 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)100.8 124 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/F1 11/Times-Bold@0 SF(9.2.)72 163
Q/F2 13/Times-Bold@0 SF(Costs of Quick-Start)5.5 E F0(This section disc\
usses the costs of Quick-Start for the connection and for the routers a\
long)100.8 189 Q(the path.)100.8 202 Q(The cost of ha)100.8 228 Q
(ving a Quick-Start pack)-.22 E(et dropped:)-.11 E -.165(Fo)100.8 241 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)100.8 254 Q 2.75
(ets. This)-.11 F(should be an unlik)2.75 E(ely situation)-.11 E
(because routers are e)100.8 267 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)100.8 280 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
293 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)100.8 306 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)100.8 319 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)100.8 332 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)100.8 345 Q -.165(ve)-.165 G
(d, so the performance cost to the connection of ha).165 E(ving a)-.22 E
(Quick-Start pack)100.8 358 Q
(et dropped is small, compared to the performance without Quick-Start.)
-.11 E(\(On the other hand, the performance dif)100.8 371 Q
(ference between Quick-Start with a Quick-Start)-.275 E(pack)100.8 384 Q
(et dropped and Quick-Start with no Quick-Start pack)-.11 E
(et dropped can be considerable.\))-.11 E(Added comple)100.8 410 Q
(xity at routers:)-.165 E(The main cost of Quick-Start at routers conce\
rns the costs of added comple)100.8 423 Q(xity)-.165 E 5.5(.T)-.715 G
(he added)-5.5 E(comple)100.8 436 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.)100.8 449 Q(The added comple)5.5 E
(xity at the routers is also some)-.165 E(what)-.275 E(moderate; it in)
100.8 462 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)100.8 475 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)100.8 488 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)100.8 501 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.)
100.8 514 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)100.8 527 Q(.)-1.221
E(The slo)100.8 553 Q 2.75(wp)-.275 G(ath in routers:)-2.75 E
(Another dra)100.8 566 Q(wback of Quick-Start is that pack)-.165 E
(ets containing the Quick-Start Request)-.11 E(message might not tak)
100.8 579 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')100.8 592 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)100.8 605 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 4.6,)-2.75 E(not all pack)100.8 618 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)100.8 631 Q -.165
(ve)-.165 G(d, or in typical en).165 E(vironments where)-.44 E
(most of the pack)100.8 644 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)100.8 657 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)100.8 670 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)100.8 683 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)100.8 696 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
709 R(W03] and [R)-.605 E
(W04] contain measurements of the impact of IP Option)-.605 E
(Processing on pack)100.8 722 Q(et round-trip times.)-.11 E(Flo)72 769 Q
204.025(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.2. [P)2.75 F
(age 33])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E(Multiple paths:)100.8 85 Q
(One limitation of Quick-Start is that it presumes that the data pack)
100.8 98 Q(ets of a connection will)-.11 E(follo)100.8 111 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)100.8 124 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)100.8 137 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(Quick-Start could gi)100.8 150 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)100.8 163 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.)100.8 176 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)
100.8 189 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)100.8 202 Q(wed initial)
-.275 E(rate.)100.8 215 Q 2.75(Ar)100.8 241 S
(outer that uses multipath routing for pack)-2.75 E
(ets within a single connection MUST NO)-.11 E(T)-.44 E(appro)100.8 254
Q .33 -.165(ve a Q)-.165 H(uick-Start request.).165 E(Quick-Start w)5.5
E(ould not perform rob)-.11 E(ustly in an en)-.22 E(vironment)-.44 E
(with multipath routing, where dif)100.8 267 Q(ferent pack)-.275 E
(ets in a connection routinely follo)-.11 E 2.75(wd)-.275 G(if)-2.75 E
(ferent)-.275 E 2.75(paths. In)100.8 280 R(such an en)2.75 E
(vironment, the Quick-Start request and some fraction of the pack)-.44 E
(ets in)-.11 E(the connection might tak)100.8 293 Q 2.75(ea)-.11 G 2.75
(nu)-2.75 G(nderutilized path, while the rest of the pack)-2.75 E
(ets tak)-.11 E 2.75(ea)-.11 G(n)-2.75 E(alternate, congested path.)
100.8 306 Q(Non-IP queues:)100.8 332 Q 2.75(Ap)100.8 345 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)
100.8 358 Q -.165(ve)-.275 G 2.75(lr).165 G 2.75(outers. As)-2.75 F(an)
2.75 E -.165(ex)100.8 371 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)100.8 384 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)100.8 397 Q
(as appropriate.)-.11 E(One w)5.5 E(ould hope that in)-.11 E
(general, IP netw)100.8 410 Q(orks are con\214gured so that non-IP queu\
es between IP routers do not end up)-.11 E
(being the congested bottlenecks.)100.8 423 Q/F1 11/Times-Bold@0 SF
(9.3.)72 462 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)100.8 488
Q(gely been of Quick-Start with def)-.198 E(ault, best-ef)-.11 E(fort)
-.275 E(traf)100.8 501 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)100.8 514 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.)100.8 527 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)100.8 540 Q 2.75(,s)-.44 G
(ince it is orthogonal to the speci\214cation of Quick-Start.)-2.75 E F1
(9.4.)72 579 Q F2(Pr)5.5 E(otection against Misbeha)-.234 E(ving Nodes)
-.325 E F0(In this section we discuss the protection ag)100.8 605 Q
(ainst senders, recei)-.055 E -.165(ve)-.275 G(rs, or colluding).165 E
(middlebox)100.8 618 Q(es lying about the Quick-Start Request.)-.165 E
(First, we note that it is not necessarily)5.5 E(in the sender')100.8
631 Q 2.75(so)-.605 G 2.75(rr)-2.75 G(ecei)-2.75 E -.165(ve)-.275 G(r')
.165 E 2.75(si)-.605 G(nterest to lie about the Quick-Start Request.)
-2.75 E(If the sender)5.5 E
(sends at too-high of an initial rate, and has a pack)100.8 644 Q
(et dropped, this does not necessarily)-.11 E(impro)100.8 657 Q .33
-.165(ve t)-.165 H(he performance of the connection, relati).165 E .33
-.165(ve t)-.275 H 2.75(ot).165 G(he case when the Quick-Start)-2.75 E
(Request w)100.8 670 Q(as not appro)-.11 E -.165(ve)-.165 G(d.).165 E
(Flo)72 769 Q 204.025(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(9.4. [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 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF 2.75
(9.4.1. Misbeha)72 85 R(ving Senders)-.275 E F0 2.75(At)100.8 111 S(ran\
sport sender could try to transmit data at a higher rate than that appr\
o)-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, or transmit at a high rate e)100.8 124 Q -.165(ve)
-.275 G 2.75(nw).165 G(ithout using Quick-Start at all.)-2.75 E(The)5.5
E(netw)100.8 137 Q(ork could use a traf)-.11 E
(\214c policer to protect ag)-.275 E(ainst such misbeha)-.055 E
(ving senders, for)-.22 E -.165(ex)100.8 150 S(ample by dropping pack)
.165 E(ets that e)-.11 E(xceed the allo)-.165 E
(wed transmission rate. The required)-.275 E(Report of Appro)100.8 163 Q
-.165(ve)-.165 G 2.75(dR).165 G(ate allo)-2.75 E(ws traf)-.275 E
(\214c policers to check that the Report of Appro)-.275 E -.165(ve)-.165
G 2.75(dR).165 G(ate)-2.75 E(does not e)100.8 176 Q
(xceed the Rate Request actually appro)-.165 E -.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)-.11 E
(pre)100.8 189 Q(vious Quick-Start Request from that connection.)-.275 E
(The required Appro)5.5 E -.165(ve)-.165 G 2.75(dR).165 G(ate report)
-2.75 E(also allo)100.8 202 Q(ws traf)-.275 E
(\214c policers to check that the sender')-.275 E 2.75(ss)-.605 G
(ending rate does not e)-2.75 E(xceed the rate)-.165 E
(in the Report of Appro)100.8 215 Q -.165(ve)-.165 G 2.75(dR).165 G
(ate.)-2.75 E(If a router or recei)100.8 241 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)100.8 254 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)100.8 267 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)100.8 280 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)100.8 293 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)100.8 306 Q 5.5(.I)
-.605 G 2.75(far)-5.5 G(outer sees a Report of Appro)-2.75 E -.165(ve)
-.165 G 2.75(dR).165 G(ate,)-2.75 E(and did not see an earlier Quick-St\
art request, then either the sender could be cheating, or)100.8 319 Q
(the connection')100.8 332 Q 2.75(sp)-.605 G(ath could ha)-2.75 E .33
-.165(ve c)-.22 H(hanged since the Quick-Start request w).165 E
(as sent.)-.11 E(In either)5.5 E(case, the router could decide to den)
100.8 345 Q 2.75(yf)-.165 G(uture Quick-Start requests from this sender)
-2.75 E 5.5(.I)-.605 G(n)-5.5 E(particular)100.8 358 Q 2.75(,i)-.44 G
2.75(ti)-2.75 G 2.75(sr)-2.75 G(easonable for the router to den)-2.75 E
2.75(yaQ)-.165 G(uick-Start request if either the sender is)-2.75 E
(cheating, or if the connection path suf)100.8 371 Q
(fers from path changes or multi-pathing.)-.275 E(If a router appro)
100.8 397 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)100.8 410 Q -.165(ve)-.275
G(ral possibilities: \(1\) the sender did not send a Report of Appro)
.165 E -.165(ve)-.165 G(d).165 E(Rate; \(2\) the Appro)100.8 423 Q -.165
(ve)-.165 G 2.75(dR).165 G(ate report w)-2.75 E(as dropped in the netw)
-.11 E(ork; or \(3\) the Appro)-.11 E -.165(ve)-.165 G 2.75(dR).165 G
(ate)-2.75 E(report took a dif)100.8 436 Q
(ferent path from the Quick-Start Request.)-.275 E(In an)5.5 E 2.75(yo)
-.165 G 2.75(ft)-2.75 G(hese three cases, the)-2.75 E(router w)100.8 449
Q(ould be justi\214ed in den)-.11 E
(ying future Quick-Start Requests from this sender)-.165 E(.)-.605 E
(In an)100.8 475 Q 2.75(yo)-.165 G 2.75(ft)-2.75 G(he abo)-2.75 E .33
-.165(ve m)-.165 H(entioned cases \(i.e., an Appro).165 E -.165(ve)-.165
G 2.75(dR).165 G(ate report that is lar)-2.75 E(ger than the)-.198 E
(Rate Request in the earlier Quick-Start request; no Appro)100.8 488 Q
-.165(ve)-.165 G 2.75(dR).165 G(ate report because of pack)-2.75 E(et)
-.11 E(drops, path changes, or the sender')100.8 501 Q 2.75(sf)-.605 G
(ailure to send one\), a traf)-2.86 E(\214c policer may assume that)
-.275 E(Quick-Start is not being used appropriately)100.8 514 Q 2.75(,o)
-.715 G 2.75(ri)-2.75 G 2.75(sb)-2.75 G(eing used in an inappropriate)
-2.75 E(en)100.8 527 Q(vironment, and tak)-.44 E 2.75(es)-.11 G
(ome corresponding action.)-2.75 E F1 2.75(9.4.2. Recei)72 566 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)100.8 592 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)100.8 605 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)100.8 618 Q
(or by zeroing the QS TTL and QS Nonce, then the recei)100.8 631 Q -.165
(ve)-.275 G 2.75(rc).165 G(an `)-2.75 E(`lie" about whether the)-.814 E
(request w)100.8 644 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.)100.8 657 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)100.8 670 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/\(2K\).)100.8 683 Q(Ho)100.8 709 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)100.8 722 Q -.165(ve)-.275 G 2.75
(rc).165 G(ould)-2.75 E(Flo)72 769 Q 195.775
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.4.2. [P)2.75 F(age 35])
-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E
(lie about whether the Quick-Start Requests were appro)100.8 85 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 98 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)100.8 111 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)100.8 124 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)100.8 137 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.)100.8 150 Q(Unfortunately)100.8 176 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)100.8 189 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)100.8 202 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.)100.8 215 Q
(As we noted abo)100.8 241 Q -.165(ve)-.165 G 2.75(,i).165 G 2.75(ti)
-2.75 G 2.75(sn)-2.75 G(ot necessarily in the recei)-2.75 E -.165(ve)
-.275 G(r').165 E 2.75(si)-.605 G(nterests to lie about whether the)
-2.75 E(rate request w)100.8 254 Q(as appro)-.11 E -.165(ve)-.165 G
(d, particularly since such lying could result in Quick-Start data).165
E(pack)100.8 267 Q(ets dropped in the netw)-.11 E
(ork due to congestion.)-.11 E/F1 11/Times-Bold@0 SF 2.75(9.4.3. Recei)
72 306 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)100.8 332 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)100.8 345 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.)100.8 358 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)100.8 371 Q 2.75(,a)
-.44 G(nd a higher Rate Request reported by the)-2.75 E(recei)100.8 384
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)100.8 397 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)100.8 410 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)100.8 423 Q
(ws that either some router along the path)-.275 E(malfunctioned \(incr\
easing the Rate Request inappropriately\), or the recei)100.8 436 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)100.8 449 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)100.8 475 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)100.8 488 Q -.165(ve)-.165 G 2.75
(dR).165 G(ate Request of X, and reports a Rate Request)-2.75 E(of Y)
100.8 501 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)100.8 514 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)100.8 540 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)100.8 553
Q(ould mak)-.11 E 2.75(ei)-.11 G 2.75(te)-2.75 G(asier for the)-2.75 E
(recei)100.8 566 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)100.8 579 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)100.8 592 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(Request used by the sender)100.8 605 Q(.)-.605 E(There are se)
100.8 631 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)100.8 644 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)100.8 657 Q
(sender)100.8 670 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.)100.8 683 Q 2.75
(As)100.8 709 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
722 Q(\214cult for recei)-.275 E -.165(ve)-.275 G(rs to guess the).165 E
(Flo)72 769 Q 195.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(9.4.3. [P)2.75 F(age 36])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(original v)100.8 85 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 98 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)100.8 111 Q
(fers limited protection in an)-.275 E 2.75(yc)-.165 G(ase.)-2.75 E(Ag)
100.8 137 Q(ain, as we noted abo)-.055 E -.165(ve)-.165 G 2.75(,i).165 G
2.75(ti)-2.75 G 2.75(sn)-2.75 G(ot necessarily in the recei)-2.75 E
-.165(ve)-.275 G(r').165 E 2.75(si)-.605 G(nterests to lie about the)
-2.75 E -.275(va)100.8 150 S(lue of the appro).275 E -.165(ve)-.165 G
2.75(dr).165 G
(ate request, particularly since such lying could result in Quick-Start)
-2.75 E(data pack)100.8 163 Q(ets dropped in the netw)-.11 E
(ork due to congestion.)-.11 E/F1 11/Times-Bold@0 SF 2.75
(9.4.4. Collusion)72 202 R(between Misbeha)2.75 E(ving Routers)-.275 E
F0(In addition to protecting ag)100.8 228 Q(ainst misbeha)-.055 E
(ving recei)-.22 E -.165(ve)-.275 G(rs, it is necessary also to protect)
.165 E(ag)100.8 241 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.)100.8 254 Q
(The ingress router could decrement the Rate)5.5 E
(Request at the ingress, with the e)100.8 267 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)100.8 280 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)100.8 293 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)100.8 319 Q
(ould be for the ingress router to inform the e)-.11 E
(gress router out-)-.165 E(of-band of the TTL Dif)100.8 332 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)100.8 345 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)100.8 358 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)100.8 371 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)100.8 384 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)100.8 397 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)
100.8 410 Q(et.)-.11 E(Ho)100.8 436 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)100.8 449 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)100.8 462 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)
100.8 475 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)100.8 488 Q
(along the path could ha)100.8 501 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)100.8 514 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)100.8 527
S(ress routers.).165 E
(In contrast, with Quick-Start, the collusion of the ingress and e)100.8
553 Q(gress routers to mak)-.165 E 2.75(ei)-.11 G(t)-2.75 E -.11(fa)
100.8 566 S(lsely appear that a Quick-Start request w).11 E(as appro)
-.11 E -.165(ve)-.165 G 2.75(dd).165 G(oes not necessarily gi)-2.75 E
.33 -.165(ve a)-.275 H(n).165 E(adv)100.8 579 Q(antage to the traf)-.275
E(\214c co)-.275 E -.165(ve)-.165 G(red by that collusion.).165 E
(If some router along the path really does)5.5 E(not ha)100.8 592 Q .33
-.165(ve e)-.22 H(nough a).165 E -.275(va)-.22 G
(ilable bandwidth to appro).275 E .33 -.165(ve t)-.165 H
(he Quick-Start request, then the Quick-).165 E(Start pack)100.8 605 Q
(ets sent as a result of the f)-.11 E(alsely-appro)-.11 E -.165(ve)-.165
G 2.75(dr).165 G(equest could be dropped in the)-2.75 E(netw)100.8 618 Q
(ork, to the resulting disadv)-.11 E(antage of the connection.)-.275 E
(Thus, while the ingress and)5.5 E -.165(eg)100.8 631 S
(ress routers could collude to pre).165 E -.165(ve)-.275 G
(nt intermediate routers from den).165 E(ying a Quick-Start)-.165 E
(request, it w)100.8 644 Q(ould not necessarily be to the connection')
-.11 E 2.75(sa)-.605 G(dv)-2.75 E(antage for this to happen.)-.275 E(In)
5.5 E(addition, the router between the ingress and e)100.8 657 Q
(gress nodes that denied the request could be)-.165 E
(monitoring connection performance, acti)100.8 670 Q -.165(ve)-.275 G
(ly penalizing nodes that seem to be using).165 E
(Quick-Start after a Quick-Start request w)100.8 683 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)100.8 696 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 w)100.8 722 Q
(as ECN-capable, and the colluding ingress and e)-.11 E
(gress routers were)-.165 E(Flo)72 769 Q 195.775
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.4.4. [P)2.75 F(age 37])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(lying about ECN-capability \
as well as about Quick-Start, then the result could be that the)100.8 85
Q(Quick-Start request f)100.8 98 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)100.8 111 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)100.8 124
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 \
\(if no intermediate router is monitoring to catch such misbeha)100.8
137 Q(vior\).)-.22 E/F1 11/Times-Bold@0 SF(9.5.)72 176 Q/F2 13
/Times-Bold@0 SF(Misbeha)5.5 E(ving Middleboxes and the IP TTL)-.325 E
F0(One possible dif)100.8 202 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 attack\
s in the netw)100.8 215 Q 2.75(ork. If)-.11 F(such a traf)100.8 228 Q
(\214c normalizer re-wrote the IP TTL, b)-.275 E
(ut did not adjust the Quick-Start TTL by)-.22 E
(the same amount, then the sender')100.8 241 Q 2.75(sm)-.605 G
(echanism for determining if the request w)-2.75 E(as appro)-.11 E -.165
(ve)-.165 G(d).165 E(by all routers along the path w)100.8 254 Q
(ould no longer be reliable.)-.11 E(Re-writing the IP TTL could)5.5 E
(result in f)100.8 267 Q(alse positi)-.11 E -.165(ve)-.275 G 2.75(s\()
.165 G(with the sender incorrectly belie)-2.75 E
(ving that the Quick-Start request)-.275 E -.11(wa)100.8 280 S 2.75(sa)
.11 G(ppro)-2.75 E -.165(ve)-.165 G(d\) as well as f).165 E(alse ne)-.11
E -.055(ga)-.165 G(ti).055 E -.165(ve)-.275 G 2.75(s\().165 G
(with the sender incorrectly belie)-2.75 E(ving that the)-.275 E
(Quick-Start request w)100.8 293 Q(as denied\).)-.11 E F1(9.6.)72 332 Q
F2(Attacks on Quick-Start)5.5 E F0
(As discussed in [SAF05], Quick-Start is vulnerable to tw)100.8 358 Q
2.75(ok)-.11 G(inds of Quick-Start attacks:)-2.75 E(\(1\) attacks to in\
crease the routers' processing and state load; and \(2\) attacks with b\
ogus)100.8 371 Q(Quick-Start requests to temporarily tie up a)100.8 384
Q -.275(va)-.22 G(ilable Quick-Start bandwidth, pre).275 E -.165(ve)
-.275 G(nting).165 E(routers from appro)100.8 397 Q
(ving Quick-Start requests from other connections.)-.165 E
(Routers can protect)5.5 E(ag)100.8 410 Q(ainst the \214rst kind of att\
ack by applying a simple limit on the rate at which Quick-Start)-.055 E
(requests will be considered by the router)100.8 423 Q(.)-.605 E
(The second kind of attack, attacks to tie up the a)100.8 449 Q -.275
(va)-.22 G(ilable Quick-Start bandwidth, is more).275 E(dif)100.8 462 Q
(\214cult to defend ag)-.275 E 2.75(ainst. As)-.055 F
(discussed in [SAF05]. Quick-Start Requests that are not)2.75 E
(going to be used, either because the)100.8 475 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)-2.75 E(denied by routers do)100.8 488 Q
(wnstream, can result in `w)-.275 E
(asting' potential Quick-Start bandwidth,)-.11 E
(resulting in routers den)100.8 501 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)100.8 514 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)100.8 527 Q
(as deplo)-.11 E(yed in a controlled en)-.11 E(vironment such as an)-.44
E(Intranet, where there w)100.8 540 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)100.8 553 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)100.8 566 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)
100.8 579 Q(ork without Quick-Start.)-.11 E([SAF05] considers the poten\
tial of Extreme Quick-Start algorithms at routers, which k)100.8 605 Q
(eep)-.11 E(per)100.8 618 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)100.8 631 Q
(ace of frequent o)-.11 E -.165(ve)-.165 G
(rly-larqe Quick-Start requests.).165 E F1(9.7.)72 670 Q F2
(Simulations with Quick-Start)5.5 E F0(Quick-Start w)100.8 696 Q(as add\
ed to the NS simulator [SH02] by Srikanth Sundarrajan, and additional)
-.11 E(functionality w)100.8 709 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.)100.8 722 Q
(The initial simulation studies from [SH02] sho)5.5 E 2.75(was)-.275 G
(igni\214cant)-2.75 E(Flo)72 769 Q 204.025
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(9.7. [P)2.75 F(age 38])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(performance impro)100.8 85 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 98 Q(-utilized en)
-.22 E 2.75(vironments. These)-.44 F
(studies are of \214le transfers, with the)2.75 E(impro)100.8 111 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)100.8 124 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.)100.8 137 Q
(The Quick-Start simulations in [SAF05] e)100.8 163 Q(xplore the follo)
-.165 E(wing: the potential bene\214t of)-.275 E
(Quick-Start for the connection; the relati)100.8 176 Q .33 -.165(ve b)
-.275 H(ene\214ts of dif).165 E(ferent router)-.275 E
(-based algorithms for)-.22 E(appro)100.8 189 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
202 Q/F1 11/Times-Bold@0 SF(10.)72 241 Q/F2 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.)100.8 267 Q
(This section)8.25 E(also discusses some of the k)100.8 280 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)100.8 293 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)100.8 306
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)100.8 319 Q
(wn or unkno)-.275 E(wn IP Options.)-.275 E F1(10.1.)72 358 Q/F3 13
/Times-Bold@0 SF(Implementation Issues f)5.5 E
(or Sending Quick-Start Requests)-.325 E F0(Section 4.6 discusses some \
of the issues with deciding the initial sending rate to request.)100.8
384 Q(Quick-Start raises additional issues about the communication betw\
een the transport)100.8 397 Q(protocol and the application, and about t\
he use of the past history with Quick-Start in the)100.8 410 Q
(end node.)100.8 423 Q
(One possibility is that a protocol implementation could pro)100.8 449 Q
(vide an API for applications to)-.165 E(indicate when the)100.8 462 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)100.8 475 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
488 Q(Some applications, such those that use TCP for b)5.5 E
(ulk transfers, do not ha)-.22 E -.165(ve)-.22 G
(interest in the transmission rate, b)100.8 501 Q(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 sent)-2.75 E(immediately)100.8 514 Q 2.75
(.B)-.715 G(ased on this, the sender implementation could decide whethe\
r Quick-Start)-2.75 E -.11(wo)100.8 527 S
(uld be useful, and what rate should be requested.).11 E
(Datagram-based real-time streaming)5.5 E
(applications, on the other hand, may ha)100.8 540 Q .33 -.165(ve a s)
-.22 H(peci\214c preference on the transmission rate and).165 E(the)
100.8 553 Q 2.75(yc)-.165 G(ould indicate the required rate e)-2.75 E
(xplicitly to the transport protocol to be used in the)-.165 E
(Quick-Start Request.)100.8 566 Q 1.76 -.88(We n)100.8 592 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)100.8 605 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)100.8 618 Q
(ets.)-.11 E F1(10.2.)72 657 Q F3(Implementation Issues f)5.5 E(or Pr)
-.325 E(ocessing Quick-Start Requests)-.234 E F0 2.75(Ar)100.8 683 S
(outer or other netw)-2.75 E
(ork host must be able to determine the approximate bandwidth of its)
-.11 E(outbound netw)100.8 696 Q(ork interf)-.11 E
(aces in order to process incoming Quick-Start rate requests,)-.11 E
(including those that originate from the host itself.)100.8 709 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
722 Q(wback of)-.165 E(Flo)72 769 Q 198.525
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(10.2. [P)2.75 F(age 39])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(not being rob)100.8 85 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 98 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)100.8 111 Q(.)-.605
E -.165(Pa)100.8 137 S
(rticular issues will arise for wireless links with v).165 E
(ariable bandwidth, where decisions will)-.275 E(ha)100.8 150 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 netw)-2.75 E
(ork host gets updates of the changing)-.11 E 2.75(bandwidth. It)100.8
163 R(seems appropriate that Quick-Start Requests w)2.75 E
(ould be handled particularly)-.11 E(conserv)100.8 176 Q(ati)-.275 E
-.165(ve)-.275 G(ly for links with v).165 E(ariable bandwidth, to a)
-.275 E -.22(vo)-.22 G(id cases where Quick-Start).22 E
(Requests are appro)100.8 189 Q -.165(ve)-.165 G
(d, the link bandwidth is reduced, and the data pack).165 E
(ets that are sent)-.11 E(end up being dropped.)100.8 202 Q(Dif)100.8
228 Q(\214cult issues also arise for paths with multi-access links \(e.\
g., Ethernet\).)-.275 E(Routers with)5.5 E
(multi-access links should be particularly conserv)100.8 241 Q(ati)-.275
E .33 -.165(ve i)-.275 H 2.75(ng).165 G(ranting Quick-Start requests.)
-2.75 E/F1 11/Times-Bold@0 SF(10.3.)72 280 Q/F2 13/Times-Bold@0 SF -.26
(Po)5.5 G(ssible Deployment Scenarios).26 E F0
(Because of possible problems discussed abo)100.8 306 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)100.8 319 Q
(ork paths, the most realistic initial deplo)-.11 E
(yment of Quick-Start w)-.11 E(ould most lik)-.11 E(ely tak)-.11 E(e)
-.11 E(place in Intranets and other controlled en)100.8 332 Q 2.75
(vironments. Quick-Start)-.44 F(is most useful on high)2.75 E(bandwidth\
-delay paths that are signi\214cantly underutilized. The primary initia\
l users of)100.8 345 Q(Quick-Start w)100.8 358 Q(ould lik)-.11 E
(ely be in or)-.11 E -.055(ga)-.198 G(nizations that pro).055 E
(vide netw)-.165 E(ork services to their users)-.11 E(and also ha)100.8
371 Q .33 -.165(ve c)-.22 H(ontrol o).165 E -.165(ve)-.165 G 2.75(ral)
.165 G(ar)-2.75 E(ge portion of the netw)-.198 E(ork path.)-.11 E(Belo)
100.8 397 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.)100.8 410 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
423 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)100.8 436 Q(.)-.605 E 2.75(*C)
100.8 462 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)100.8 475 Q(ork capacity)-.11 E 2.75
(,w)-.715 G(ith netw)-2.75 E
(orks that are underutilized for much of the time.)-.11 E(Such)5.5 E(In\
tranets might also include high-bandwidth and high-delay paths to remot\
e sites.)100.8 488 Q(In such)5.5 E(an en)100.8 501 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)100.8 514 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)100.8 527 Q
(orks used for scienti\214c computing.)-.11 E 2.75(*G)100.8 553 S
(PRS: Quick-Start could also be useful in high-delay en)-2.75 E
(vironments of Cellular W)-.44 E(ide-)-.44 E(Area W)100.8 566 Q
(ireless Netw)-.44 E
(orks such as the GPRS [BW97] and their enhancements and ne)-.11 E(xt)
-.165 E(generations. F)100.8 579 Q(or e)-.165 E
(xample, GPRS EDGE \(Enhanced Data for GSM Ev)-.165 E(olution\) is e)
-.22 E(xpected)-.165 E(to pro)100.8 592 Q
(vide wireless bandwidth of up to 384 Kbps \(roughly 32 1500-byte pack)
-.165 E(ets per)-.11 E
(second\) while the GPRS round-trip times range typically from fe)100.8
605 Q 2.75(wh)-.275 G(undred milliseconds to)-2.75 E -.165(ove)100.8 618
S 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 [GP)-.11 E(AR02]. In)
-1.012 E(addition, these netw)100.8 631 Q(orks sometimes ha)-.11 E .33
-.165(ve v)-.22 H(ariable additional delays due to resource)-.11 E
(allocation that could be a)100.8 644 Q -.22(vo)-.22 G(ided by k).22 E
(eeping the connection path constantly utilized, starting)-.11 E
(from initial slo)100.8 657 Q 2.75(w-start. Thus,)-.275 F
(Quick-Start could be of signi\214cant bene\214t to users in these)2.75
E(en)100.8 670 Q(vironments.)-.44 E 2.75(*P)100.8 696 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)100.8 709 Q(ation de\
lays on the order of 250 ms while the bandwidth can be measured in)-.055
E(me)100.8 722 Q -.055(ga)-.165 G(bits per second [RFC2488]. Because of\
 the considerable bandwidth-delay product on).055 E(Flo)72 769 Q 198.525
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(10.3. [P)2.75 F(age 40])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(the link, TCP')100.8 85 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 98 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.)100.8 111 Q/F1
11/Times-Bold@0 SF(10.4.)72 150 Q/F2 13/Times-Bold@0 SF -.975(Wo)5.5 G
(uld QuickStart pack).975 E(ets tak)-.13 E 3.25(et)-.13 G(he slo)-3.25 E
3.25(wp)-.13 G(ath in r)-3.25 E(outers?)-.234 E F0(Ho)100.8 176 Q 2.75
(wm)-.275 G(uch delay w)-2.75 E(ould the slo)-.11 E 2.75(wp)-.275 G
(ath add to the processing time for Quick-Start request)-2.75 E(pack)
100.8 189 Q 2.75(ets? In)-.11 F(addition, if QuickStart request pack)
2.75 E(ets took the slo)-.11 E 2.75(wp)-.275 G
(ath, this could add stress)-2.75 E(to routers, though routers could al)
100.8 202 Q -.11(wa)-.11 G
(ys rate-limit the number of QuickStart request pack).11 E(ets)-.11 E
(the)100.8 215 Q 2.75(ya)-.165 G(re willing to consider)-2.75 E(.)-.605
E F1(10.5.)72 254 Q F2 3.25(AC)5.5 G(omparison with the Deployment Pr)
-3.25 E(oblems of ECN)-.234 E F0(Gi)100.8 280 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)100.8 293 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.)100.8 306 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
319 Q 2.75(su)-.605 G(se of Quick-Start requires)-2.75 E(its deplo)100.8
332 Q(yment on all of the routers along the end-to-end path.)-.11 E
(Second, unlik)5.5 E 2.75(eE)-.11 G(CN, which)-2.75 E
(uses an allocated \214eld in the IP header)100.8 345 Q 2.75(,Q)-.44 G
(uick-Start requires the e)-2.75 E(xtra complications of an)-.165 E
(IP Option.)100.8 358 Q(Ho)100.8 384 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 the Inte\
rnet, because the potential bene\214ts of Quick-Start to)100.8 397 Q
(the user are considerably more dramatic than those of ECN.)100.8 410 Q
(Rather than simply replacing)5.5 E(the occasional dropped pack)100.8
423 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)100.8 436 Q(vironments.)-.44 E
F1(11.)72 475 Q/F3 14/Times-Bold@0 SF(Related W)5.5 E(ork)-1.05 E F0
(The Quick-Start proposal, tak)100.8 501 Q
(en together with HighSpeed TCP [RFC3649] or other)-.11 E(transport pro\
tocols for high-bandwidth transfers, could go a signi\214cant w)100.8
514 Q(ay to)-.11 E -.11(wa)-.275 G(rds).11 E -.165(ex)100.8 527 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)100.8 540 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
553 Q(ould not help in making more precise use of the)-.11 E -.22(av)
100.8 566 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)100.8 579 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)100.8 592 Q .33 -.165(ve c)-.275 H
(onnections.).165 E(In addition, an)100.8 618 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)
100.8 631 Q
(xplicit information from routers, and of approaches that use)-.165 E
(more \214ne-grained feedback from routers as part of a lar)100.8 644 Q
(ger congestion control mechanism.)-.198 E 1.76 -.88(We d)100.8 657 T
(iscuss se).88 E -.165(ve)-.275 G(ral classes of proposals \(no e).165 E
(xplicit feedback from routers; e)-.165 E(xplicit)-.165 E(feedback abou\
t the initial rate; more \214ne-grained feedback from routers; and prop\
osals)100.8 670 Q(based on lo)100.8 683 Q(wer)-.275 E(-than-best-ef)-.22
E(fort service\) in the sections belo)-.275 E -.715(w.)-.275 G(Flo)72
769 Q 206.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(11. [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 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF(11.1.)
72 85 Q/F2 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)100.8 111 Q
(ould be for senders to use information from the pack)-.11 E
(et streams to learn)-.11 E(about the a)100.8 124 Q -.275(va)-.22 G
(ilable bandwidth, without e).275 E(xplicit information from routers.)
-.165 E(These techniques)5.5 E -.11(wo)100.8 137 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)100.8 150 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)100.8 163 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)100.8 176 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)100.8 189 Q
(werful that is possible *with* e)-.275 E(xplicit)-.165 E
(feedback, it is also possible that approaches that are more aggressi)
100.8 202 Q .33 -.165(ve t)-.275 H(han slo).165 E(w-start are)-.275 E
(possible without e)100.8 215 Q(xplicit feedback from routers.)-.165 E
(Periodic pack)100.8 241 Q(et streams:)-.11 E([JD02] e)100.8 254 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.)100.8 267 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')100.8 280 Q 2.75(sr)-.605 G
(ate is higher than the a)-2.75 E -.275(va)-.22 G(ilable bandwidth.).275
E(While)5.5 E([JD02] states that the proposed mechanism does not cause \
signi\214cant increases in netw)100.8 293 Q(ork)-.11 E
(utilization, losses, or delays when done by one \215o)100.8 306 Q 2.75
(wa)-.275 G 2.75(tat)-2.75 G(ime, the approach could be)-2.75 E
(problematic if conducted concurrently by a number of \215o)100.8 319 Q
2.75(ws. [JD02])-.275 F(also gi)2.75 E -.165(ve)-.275 G 2.75(sa).165 G
(n)-2.75 E -.165(ove)100.8 332 S(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 bandwidth from pack).275 E(et)-.11 E(trains.)100.8 345
Q(Swift-Start:)100.8 371 Q
(The Swift Start proposal from [PRAKS02] combines pack)100.8 384 Q
(et-pair and pack)-.11 E(et-pacing)-.11 E 2.75(techniques. An)100.8 397
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)100.8 410
S(ailable bandwidth along the path.)-.055 E
(This estimate is then used to dramatically increase the)5.5 E
(congestion windo)100.8 423 Q 2.75(wd)-.275 G(uring the second R)-2.75 E
(TT of data transmission.)-.66 E(SP)100.8 449 Q(AND:)-1.012 E
(In the TCP/SP)100.8 462 Q
(AND proposal from [ZQK00] for speeding up short data transfers, netw)
-1.012 E(ork)-.11 E(performance information w)100.8 475 Q
(ould be shared among man)-.11 E 2.75(yc)-.165 G
(o-located hosts to estimate each)-2.75 E(connection')100.8 488 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)
100.8 501 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)100.8 514 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
527 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(While continued research on the limits of the\
 ability of TCP and other transport protocols)100.8 553 Q(to learn of a)
100.8 566 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)100.8 579 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)
100.8 605 Q(aster than implicit feedback:)-.11 E(One adv)100.8 618 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)100.8 631
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
657 Q 2.75(As)100.8 670 S(econd adv)-2.75 E(antage of e)-.275 E
(xplicit feedback from the routers is that the a)-.165 E -.275(va)-.22 G
(ilable bandwidth).275 E
(along the path does not necessarily map to the allo)100.8 683 Q
(wed sending rate for an indi)-.275 E(vidual \215o)-.275 E -.715(w.)
-.275 G(As an e)100.8 696 Q(xample, if the TCP sender sends four pack)
-.165 E(ets back-to-back in the initial windo)-.11 E -.715(w,)-.275 G
(and the TCP recei)100.8 709 Q -.165(ve)-.275 G 2.75(rr).165 G
(eports that the data pack)-2.75 E(ets were recei)-.11 E -.165(ve)-.275
G 2.75(dw).165 G(ith roughly the same)-2.75 E(spacing as the)100.8 722 Q
2.75(yw)-.165 G(ere transmitted, does this mean that the \215o)-2.75 E
2.75(wc)-.275 G(an infer an underutilized)-2.75 E(Flo)72 769 Q 198.525
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(11.1. [P)2.75 F(age 42])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E 2.75(path? And)100.8 85 R
(ho)2.75 E 2.75(wf)-.275 G(ast can the \215o)-2.86 E 2.75(ws)-.275 G
(end in the ne)-2.75 E(xt round-trip time?)-.165 E
(Do the results depend)5.5 E(on the le)100.8 98 Q -.165(ve)-.275 G 2.75
(lo).165 G 2.75(fs)-2.75 G(tatistical multiple)-2.75 E
(xing at the congested link, and on the number of \215o)-.165 E(ws)-.275
E(attempting a f)100.8 111 Q(aster start-up at the same time?)-.11 E/F1
11/Times-Bold@0 SF(11.2.)72 150 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)100.8 176 Q(ge)-.198 E
(initial windo)100.8 189 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)100.8 202 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)100.8 215 Q 4.18
-.715(w. T)-.275 H(he proposal w).715 E(ould be that)-.11 E
(congested routers w)100.8 228 Q
(ould use this information in the \214rst data pack)-.11 E
(et to drop or delay man)-.11 E(y)-.165 E(or all of the pack)100.8 241 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)100.8 254 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)100.8 267 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)100.8 280 Q(pack)100.8 293 Q(et of a lar)-.11 E
(ge initial windo)-.198 E -.715(w.)-.275 G(Ob)100.8 319 Q
(viously there w)-.165 E
(ould be a number of questions to consider about an approach of)-.11 E
(optimistic sending.)100.8 332 Q(\(1\) Incremental deplo)100.8 358 Q
(yment:)-.11 E(One question w)100.8 371 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)100.8 384 Q
(et information describing the)-.11 E(initial windo)100.8 397 Q -.715
(w.)-.275 G(\(2\) Congestion collapse:)100.8 423 Q
(There could also be concerns about congestion collapse if man)100.8 436
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)100.8 449 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)
100.8 462 Q(ets that are only going to be dropped do)-.11 E(wnstream.)
-.275 E(\(3\) Distrib)100.8 488 Q(uted Denial of Service attacks:)-.22 E
2.75(At)100.8 501 S(hird k)-2.75 E .33 -.165(ey q)-.11 H(uestion w).165
E(ould be the potential role of optimistic senders in amplifying the)
-.11 E(damage done by a Distrib)100.8 514 Q
(uted Denial of Service \(DDoS\) attack.)-.22 E
(\(4\) Performance hits if a pack)100.8 540 Q(et is dropped:)-.11 E 2.75
(Af)100.8 553 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)100.8 566 Q
(ws.)-.275 E F1(11.3.)72 605 Q F2 -.325(Fa)5.5 G
(st Start-ups with other Inf).325 E(ormation fr)-.325 E(om Routers)-.234
E F0(There ha)100.8 631 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)100.8 644 Q
(xplicit information from the routers along the path.)-.165 E
(An IP Option about the free b)100.8 670 Q(uf)-.22 E(fer size:)-.275 E
(In related w)100.8 683 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)100.8 696 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)100.8 709 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)100.8 722 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
(Flo)72 769 Q 198.525(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75
(11.3. [P)2.75 F(age 43])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E
(sender already had an estimate of the round-trip time.)100.8 85 Q
(The Performance T)100.8 111 Q(ransparenc)-.385 E 2.75(yP)-.165 G
(rotocol:)-2.75 E(The Performance T)100.8 124 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)100.8 137 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)100.8 150 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.)100.8 163 Q(ETEN:)100.8 189 Q
(Additional proposals for end nodes to collect e)100.8 202 Q
(xplicit information from routers include)-.165 E(Explicit T)100.8 215 Q
(ransport Error Noti\214cation \(ETEN\), which includes a cumulati)-.385
E .33 -.165(ve m)-.275 H(echanism to).165 E(notify endpoints of aggre)
100.8 228 Q -.055(ga)-.165 G
(te congestion statistics along the path [KAPS02].).055 E/F1 11
/Times-Bold@0 SF(11.4.)72 267 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-gra\
ined congestion-related feedback from routers include XCP)100.8 293 Q
([KHR02], MaxNet [MaxNet], and AntiECN marking [K03].)100.8 306 Q
(Section A.6 discusses in)5.5 E(more detail the relationship between Qu\
ick-Start and proposals for more \214ne-grained per)100.8 319 Q(-)-.22 E
(pack)100.8 332 Q(et feedback from routers.)-.11 E(XCP:)100.8 358 Q
(Proposals such as XCP for ne)100.8 371 Q 2.75(wc)-.275 G
(ongestion control mechanisms based on more feedback)-2.75 E
(from routers are more po)100.8 384 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)100.8 397 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.)100.8 410 Q(The per)5.5 E(-)-.22 E(pack)100.8 423 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')
100.8 436 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(wledged.)-.275 E(AntiECN:)
100.8 462 Q(The AntiECN proposal is for a single bit in the pack)100.8
475 Q(et header that routers could set to)-.11 E(indicate that the)100.8
488 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)100.8 501 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)100.8 514 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(11.5.)72 553 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)100.8 579 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)100.8 592 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)
100.8 605 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.)100.8 618 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 w)100.8 631 Q
(ould be used by transport protocols that start-up f)-.11 E
(aster than slo)-.11 E 2.75(w-start. F)-.275 F(or)-.165 E -.165(ex)100.8
644 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)100.8 657 Q
(\214c, with routers con\214gured to use strict priority queueing.)-.275
E 2.75(As)100.8 683 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)100.8 696 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)100.8 709 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)100.8 722 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(Flo)72 769 Q 198.525
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(11.5. [P)2.75 F(age 44])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(ef)100.8 85 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 98 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)100.8 111 Q(ault slo)-.11 E
(w-start mechanisms of TCP)-.275 E(.)-1.221 E 1.76 -.88(We n)100.8 137 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
150 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(best-ef)100.8 163 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.)100.8 176 Q/F1 11/Times-Bold@0 SF(12.)72 215 Q/F2 14
/Times-Bold@0 SF(Security Considerations)5.5 E F0(Sections 9.4 and 9.6 \
discuss the security considerations related to Quick-Start.)100.8 241 Q
(Section 9.4)5.5 E(discusses the potential ab)100.8 254 Q
(use of Quick-Start by senders or recei)-.22 E -.165(ve)-.275 G
(rs lying about whether the).165 E(request w)100.8 267 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)100.8 280 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
293 Q(et headers.)-.11 E
(All of these problems could result in the sender using a Rate)5.5 E
(Request that w)100.8 306 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)100.8 319 Q
(act denied by at least one router along the path.)-.11 E
(This inappropriate use of Quick-Start)5.5 E -.11(wo)100.8 332 S
(uld result in congestion and an unacceptable le).11 E -.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
(congestion could also be part of a Denial of Service attack.)100.8 345
Q(Section 9.6 discusses a potential attack on the routers' processing a\
nd state load from an)100.8 371 Q(attack of Quick-Start Requests.)100.8
384 Q(Section 9.6 also discusses a potential attack on the)5.5 E -.22
(av)100.8 397 S(ailable Quick-Start bandwidth by sending bogus Quick-St\
art requests for bandwidth that)-.055 E(will not in f)100.8 410 Q
(act be used.)-.11 E
(Section 4.6.2 discusses the potential problem of pack)100.8 436 Q
(ets with Quick-Start Requests)-.11 E(dropped by middlebox)100.8 449 Q
(es along the path.)-.165 E
(As discussed in Section 5, for IPv4 IPsec Authentication Header Inte)
100.8 475 Q(grity Check V)-.165 E(alue)-1.221 E(\(AH ICV\) calculation,\
 the Quick-Start option MUST be treated as a mutable IPv4 option,)100.8
488 Q(and hence completely zeroed for AH ICV calculation purposes; this\
 is also the treatment)100.8 501 Q
(required by RFC 2402 for unrecognized IPv4 options.)100.8 514 Q
(The IPv6 Quick-Start option')5.5 E(s)-.605 E(IAN)100.8 527 Q(A-allocat\
ed option type indicates that it is a mutable option, hence, according \
to RFC)-.385 E
(2402, its option data MUST be zeroed for AH ICV computation purposes.)
100.8 540 Q(See RFC 2402)5.5 E(for further e)100.8 553 Q(xplanation.)
-.165 E(Section 6.2 discusses possible problems of Quick-Start used by \
connections carried o)100.8 579 Q -.165(ve)-.165 G(r).165 E
(simple tunnels that are not compatible with Quick-Start.)100.8 592 Q
(In this case it is possible that a)8.25 E
(Quick-Start Request is erroneously considered appro)100.8 605 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)100.8 618 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 F1(13.)72 657 Q F2(Conclusions)5.5 E F0 1.76 -.88(We a)100.8 683
T(re presenting the Quick-Start mechanism as a simple, understandable, \
and).88 E(incrementally-deplo)100.8 696 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)100.8 709 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)100.8 722 Q 2.75(vironments. W)-.44 F 2.75(ee)-.88 G
(xpect there will be an increasing number of)-2.915 E(Flo)72 769 Q
206.775(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(13. [P)2.75 F
(age 45])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E -.165(ove)100.8 85 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 98 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)
100.8 111 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
124 Q(vide feedback and e)-.165 E
(xperimentation on issues relating to Quick-Start.)-.165 E/F1 11
/Times-Bold@0 SF(14.)72 163 Q/F2 14/Times-Bold@0 SF(Ackno)5.5 E
(wledgements)-.14 E F0(The authors wish to thank Mark Handle)100.8 189 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
202 Q(ransport Services W)-.385 E(orking Group, and)-.88 E
(members of IP)100.8 215 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)100.8 228 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)100.8 241 Q 2.75(,a)
-.44 G(nd for the initial simulation study)-2.75 E(.)-.715 E(Man)100.8
254 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 QuickStart and IP).165 E 2.75(tunnels. W)100.8 267 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)100.8 280 Q
(an, Gorry F)-.055 E(airhurst, John Heidemann, P)-.165 E(aul Hyder)-.165
E 2.75(,D)-.44 G(ina Katabi and V)-2.75 E(ern P)-1.221 E(axson for)-.165
E 2.75(feedback. This)100.8 293 R(draft b)2.75 E
(uilds upon the concepts described in [RFC3390], [AHO98],)-.22 E
([RFC2415], and [RFC3168].)100.8 306 Q(Some of the te)5.5 E
(xt on Quick-Start in tunnels w)-.165 E(as borro)-.11 E(wed)-.275 E
(directly from RFC 3168.)100.8 319 Q(This document is the de)100.8 345 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)100.8 358 Q -.165(ve)-.165 G(ry).165 E(.)
-.715 E F1(A.)72 397 Q F2(Design Decisions)5.5 E F1(A.1.)72 436 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
462 Q(sender to the recei)100.8 475 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)100.8 488 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 used)
100.8 501 Q(for deli)100.8 514 Q -.165(ve)-.275 G
(ring the Quick-Start Request.).165 E F1 2.75(A.1.1. ICMP)72 553 R F0
(Being a control protocol used between Internet nodes, one could ar)
100.8 579 Q(gue that ICMP is the)-.198 E
(ideal method for requesting a permission for f)100.8 592 Q
(aster startup from routers.)-.11 E(The ICMP header)5.5 E(is abo)100.8
605 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
618 Q -.275(va)-.275 G(lent of the Quick-Start IP).275 E(option w)100.8
631 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)100.8 644 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].)100.8 657 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)100.8 670 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)100.8 683 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)100.8 696 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)100.8 709 Q(as not)-.11 E(appro)100.8
722 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(Flo)72 769 Q 193.333
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.1.1. [P)2.75 F(age 46])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(the sender w)100.8 85 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 98 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)100.8 111 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)100.8 124 Q
(ould need the source and destination port numbers for demultiple)-.11 E
(xing at the end)-.165 E 2.75(nodes. If)100.8 137 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)100.8 150 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.)100.8 163 Q
(One bene\214t of using ICMP w)100.8 189 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)100.8 202 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)100.8 215 Q
(es were blocking pack)-.165 E
(ets with Quick-Start Requests, using the Quick-)-.11 E
(Start Request in a separate ICMP pack)100.8 228 Q(et w)-.11 E
(ould mean that the middlebox beha)-.11 E(vior w)-.22 E(ould)-.11 E
(not af)100.8 241 Q(fect the connection as a whole.)-.275 E(\(T)5.5 E
2.75(og)-.88 G(et this rob)-2.75 E(ustness to middlebox)-.22 E
(es with TCP)-.165 E(using an IP Quick-Start Option, one w)100.8 254 Q
(ould ha)-.11 E .33 -.165(ve t)-.22 H 2.75(oh).165 G -2.475 -.22(av e)
-2.75 H 2.75(aT)2.97 G(CP-le)-2.75 E -.165(ve)-.275 G 2.75(lQ).165 G
(uick-Start Request)-2.75 E(pack)100.8 267 Q
(et that could be sent concurrently b)-.11 E
(ut separately from the TCP SYN pack)-.22 E(et.\))-.11 E(Ho)100.8 293 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
306 Q(es may not forw)-.165 E(ard the ICMP Quick-Start Request pack)-.11
E 2.75(ets. \(If)-.11 F(an ICMP Reply)2.75 E(pack)100.8 319 Q
(et from a router to the sender is dropped in the netw)-.11 E
(ork, the sender w)-.11 E(ould still kno)-.11 E(w)-.275 E
(that the request w)100.8 332 Q(as not appro)-.11 E -.165(ve)-.165 G
(d, as stated earlier).165 E 2.75(,s)-.44 G 2.75(ot)-2.75 G(his w)-2.75
E(ould not be as serious of a)-.11 E 2.75(problem.\) In)100.8 345 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)100.8 358 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 tunnel mode [RFC2401].)100.8
371 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)100.8 384 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-)100.8 410 Q(party malicious hosts that are not p\
ossible when the control information is carried in-band)100.8 423 Q
(with the IP pack)100.8 436 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)100.8 449 Q
(ould cause a small amount of additional traf)-.11 E(\214c in the)-.275
E(netw)100.8 462 Q(ork, which is not the case when using IP options.)
-.11 E/F1 11/Times-Bold@0 SF 2.75(A.1.2. RSVP)72 501 R F0 -.44(Wi)100.8
527 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)100.8 540 Q
(xpected to process RSVP pack)-.165 E(ets more)-.11 E -.165(ex)100.8 553
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)100.8 566 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)100.8 579 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)100.8 592 S(uld not \
require periodical refreshing of soft state, because Quick-Start does n\
ot require).11 E(per)100.8 605 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)100.8 618 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)100.8 631 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)100.8 644 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.)100.8 657 Q
(If RSVP w)100.8 683 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
696 Q(ould be included in the RSVP P)-.11 E
(ath message that is sent from the sender to)-.165 E(recei)100.8 709 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)100.8 722 Q(Flo)72 769 Q 193.333
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.1.2. [P)2.75 F(age 47])
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(September 2006)2.75 E(March 2006)106.935 E(equi)100.8 85 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 98 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
111 Q(Start Request object, it w)100.8 124 Q
(ould reject the entire RSVP message and send an RSVP P)-.11 E(athErr)
-.165 E(message back to the sender)100.8 137 Q 5.5(.W)-.605 G
(hen an RSVP message with the Quick-Start Request object)-5.5 E
(reaches the recei)100.8 150 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)100.8 163 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
176 Q(as dropped along the path, the)-.11 E(transport sender w)100.8 189
Q(ould simply proceed with the normal congestion control procedures.)
-.11 E(Much of the discussion about bene\214ts and dra)100.8 215 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)100.8 228 Q(as)
-.11 E(transmitted in a separate pack)100.8 241 Q
(et instead of as an IP option, the transport protocol pack)-.11 E(et)
-.11 E(deli)100.8 254 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)100.8 267 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)100.8 280 Q
(xpected to be similar: middlebox)-.165 E(es in the netw)-.165 E
(ork may)-.11 E(not be able to forw)100.8 293 Q
(ard the Quick-Start Request messages, and the IP tunnels might cause)
-.11 E(problems for processing the Quick-Start Requests.)100.8 306 Q/F1
11/Times-Bold@0 SF(A.2.)72 345 Q/F2 13/Times-Bold@0 SF(Alter)5.5 E
(nate Encoding Functions)-.195 E F0(In this section we look at alternat\
e encoding functions for the Rate Request \214eld in the)100.8 371 Q
(Quick-Start Request.)100.8 384 Q
(The main requirements for this function is that it should ha)5.5 E .33
-.165(ve a)-.22 H(suf)100.8 397 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.)100.8 410 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)100.8 423 Q
(store the table gi)100.8 436 Q(ving the mapping between the v)-.275 E
(alue N in the Rate Request \214eld, and the)-.275 E
(actual rate request f\(N\).)100.8 449 Q
(In this section we consider possible encoding methods for Rate)5.5 E
(Request \214elds of dif)100.8 462 Q(ferent sizes, including four)-.275
E(-bit, eight-bit, and lar)-.22 E(ger Rate Request)-.198 E(\214elds.)
100.8 475 Q(Linear functions:)100.8 501 Q(One possible proposal w)100.8
514 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)
100.8 527 Q(ed v)-.165 E(alue of M.)-.275 E(Thus, for the)5.5 E -.275
(va)100.8 540 S(lue N in the Rate Request \214eld, the requested rate w)
.275 E(ould be M*N Kbps.)-.11 E(Po)100.8 566 Q(wers of tw)-.275 E(o:)
-.11 E(If a granularity of f)100.8 579 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)100.8 592 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.)100.8 605
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)100.8 618 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)100.8 631 Q
(ould be from 80 Kbps to 40*2^255 Kbps.)-.11 E(This)5.5 E(clearly w)
100.8 644 Q(ould be an unnecessarily lar)-.11 E(ge request range.)-.198
E -.165(Fo)100.8 670 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)100.8 683 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)100.8 696 Q(use other mechanisms, such as the e)100.8 709
Q(xplicit reserv)-.165 E(ation of bandwidth.)-.275 E
(If an upper limit of)5.5 E(1.3 Gbps w)100.8 722 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(Flo)72 769
Q 201.583(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.2. [P)2.75 F
(age 48])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(If the granularity of f)
100.8 85 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 98 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)100.8 111 Q(xponential functions.)
-.165 E 2.75(Am)100.8 137 S(antissa and e)-2.75 E
(xponent representation:)-.165 E
(Section 4.4 of [B05] suggests a mantissa and e)100.8 150 Q
(xponent representation for the Quick-Start)-.165 E(encoding function.)
100.8 163 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)
100.8 176 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)100.8 189 Q
(xponent \214eld for e of 8 bits.)-.165 E(This representation)5.5 E -.11
(wo)100.8 202 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)100.8 215 Q 2.75(oe)-.11 G
(ncoding used in this document.)-2.75 E
(Constraints of the transport protocol:)100.8 241 Q 1.76 -.88(We n)100.8
254 T(ote that the Rate Request is also constrained by the abilities of\
 the transport protocol.).88 E -.165(Fo)100.8 267 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)100.8 280 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.)100.8 293 Q/F1 11/Times-Bold@0 SF(A.3.)72
332 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)100.8 358 Q(or in pack)
100.8 371 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)100.8 384 Q
.33 -.165(ve o)-.275 H 2.75(ft).165 G(he router)-2.75 E(.)-.605 E -.165
(Fo)100.8 410 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.)
100.8 423 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)100.8 436 Q(et headers.)-.11 E(Other transport protocols w)100.8
449 Q(ould concei)-.11 E -.275(va)-.275 G
(bly use the Quick-Start Request directly in).275 E(pack)100.8 462 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)100.8 475 Q(ets.)-.11 E
(The assumption of this draft is that the router only appro)100.8 501 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.)100.8 514 Q -.165(Fo)
5.5 G 2.75(rt).165 G(his, the router could measure the)-2.75 E -.22(av)
100.8 527 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.)100.8 540 Q(If the Quick-Start Request w)100.8 566 Q
(as in bytes per second, and applied only to the data payload,)-.11 E
(then the router w)100.8 579 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)100.8 592 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)100.8 605 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.)100.8 618 Q
(Therefore, for a Quick-Start Request in)5.5 E(bytes per second, it mak)
100.8 631 Q
(es most sense for this to include the transport and IP headers as)-.11
E(well as the data payload.)100.8 644 Q
(Of course, this will be at best a rough approximation on the part)5.5 E
(of the sender; the transport-le)100.8 657 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)100.8 670 Q 2.75(wn)-.275 G
(othing at all about the separate headers added in IP)-2.75 E
(tunnels do)100.8 683 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)100.8 696 Q(.)-.715 E
(It has been suggested that the router could possibly use information f\
rom the MSS option)100.8 722 Q(Flo)72 769 Q 201.583
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.3. [P)2.75 F(age 49])
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(September 2006)2.75 E(March 2006)106.935 E(in the TCP pack)100.8 85 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 98 Q
(ets per second to bytes per second, or vice v)-.11 E 2.75(ersa. The)
-.165 F(MSS option is de\214ned as the)2.75 E
(maximum MSS that the TCP sender e)100.8 111 Q(xpects to recei)-.165 E
-.165(ve)-.275 G 2.75(,n).165 G(ot the maximum MSS that the)-2.75 E
(TCP sender plans to send [RFC793].)100.8 124 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 often the case that this MSS)-2.75 E(also applies as an upper \
bound on the MSS used by the TCP sender in sending.)100.8 137 Q 1.76
-.88(We n)100.8 163 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)100.8 176 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)100.8 189 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].)
100.8 202 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)100.8 215 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.)100.8 228 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].)100.8 241 Q -.165
(Fo)100.8 267 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)100.8 280 Q
(et headers.)-.11 E 1.76 -.88(We h)100.8 306 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)100.8 319 Q
(what more rob)-.275 E(ust, particularly to routers.)-.22 E/F1 11
/Times-Bold@0 SF(A.4.)72 358 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)100.8 384 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)100.8 397 Q(ws:)-.275
E(\(1\) T)100.8 423 Q(otal Rate: The requested Rate Request is the requ\
ested total rate for the connection,)-.88 E
(including the current rate; or)100.8 436 Q(\(2\) Additional Rate: The \
requested Rate Request is the requested increase in the total rate)100.8
462 Q(for that connection, o)100.8 475 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,)100.8 501 Q(and there is no dif)100.8 514 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)100.8 527 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)100.8 540 Q(higher rate.)100.8
553 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)100.8 566
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)100.8 579 Q .33 -.165(ve c)-.22 H
(hosen the `T).165 E(otal Rate' semantics.)-.88 E(The T)100.8 605 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)100.8 618 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)
100.8 631 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)100.8 644 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)100.8 657 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)100.8 670 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)100.8 683 Q
(wing the current sending rates of the dif)-.275 E(ferent)-.275 E<8d6f>
100.8 696 Q(ws.)-.275 E
(The Additional Rate semantics also lends itself to g)100.8 722 Q
(aming by the connection, with senders)-.055 E(Flo)72 769 Q 201.583
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.4. [P)2.75 F(age 50])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E
(sending frequent Quick-Start Requests in the hope of g)100.8 85 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 98 Q(connection of sending a rate request o)100.8 111 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
(an *additional* rate with each rate request, o)100.8 124 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')100.8 137 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)
100.8 150 Q(act granted.)-.11 E(Appendix D discusses a Report of Curren\
t Sending Rate as one possible function in the)100.8 176 Q
(Quick-Start Option.)100.8 189 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(A.5.)72 241 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 4.5 discusses TCP')100.8 267 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)100.8 280 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)100.8 306 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)100.8 319 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)100.8 332 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)
100.8 345 Q(ork as a whole.)-.11 E(The pack)5.5 E(et loss)-.11 E
(in the initial windo)100.8 358 Q 2.75(wi)-.275 G
(ndicates that Quick-Start f)-2.75 E
(ailed in \214nding an appropriate congestion)-.11 E(windo)100.8 371 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)100.8 397
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(\(W)100.8 410 Q(-D\)/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)100.8 423 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)100.8 436 Q(ets deli)-.11 E
-.165(ve)-.275 G(red is a good indication of the).165 E(appropriate a)
100.8 449 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
462 Q 2.75(ork. W)-.11 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)100.8 475 Q
(ork with a range of pack)-.11 E(et dropping)-.11 E
(mechanisms at the router)100.8 488 Q 2.75(,a)-.44 G
(nd we cannot recommend it at this time.)-2.75 E(Another dra)100.8 514 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)100.8 527 Q(et in the initial windo)-.11 E 2.75(wi)-.275 G 2.75
(sd)-2.75 G(ropped is that an)-2.75 E 2.75(ys)-.165 G
(uch approaches could gi)-2.75 E .33 -.165(ve t)-.275 H(he TCP).165 E
(recei)100.8 540 Q -.165(ve)-.275 G 2.75(ra).165 G 2.75(ni)-2.75 G
(ncenti)-2.75 E .33 -.165(ve t)-.275 H 2.75(ol).165 G
(ie about the Quick-Start request.)-2.75 E(That is, if the sender re)5.5
E -.165(ve)-.275 G(rts to).165 E(slo)100.8 553 Q
(w-start when a Quick-Start pack)-.275 E
(et is dropped, then it is generally not to the recei)-.11 E -.165(ve)
-.275 G(r').165 E(s)-.605 E(adv)100.8 566 Q(antage to report a lar)-.275
E(ger rate request than w)-.198 E(as actually appro)-.11 E -.165(ve)
-.165 G 2.75(di).165 G 2.75(ft)-2.75 G(he result is going to)-2.75 E
(be a Quick-Start pack)100.8 579 Q(et dropped in the netw)-.11 E 2.75
(ork. Ho)-.11 F(we)-.275 E -.165(ve)-.275 G .88 -.44(r, i).165 H 2.75
(ft).44 G(he recei)-2.75 E -.165(ve)-.275 G 2.75(rb).165 G
(ene\214ts from a)-2.75 E(lar)100.8 592 Q(ger Quick-Start windo)-.198 E
2.75(we)-.275 G -.165(ve)-3.025 G 2.75(nw).165 G(hen the lar)-2.75 E
(ger windo)-.198 E 2.75(wr)-.275 G(esults in Quick-Start pack)-2.75 E
(ets)-.11 E(dropped in the netw)100.8 605 Q(ork, then the recei)-.11 E
-.165(ve)-.275 G 2.75(rh).165 G(as a greater incenti)-2.75 E .33 -.165
(ve t)-.275 H 2.75(ol).165 G(ie about the recei)-2.75 E -.165(ve)-.275 G
(d).165 E(rate request, in an ef)100.8 618 Q
(fort to get the sender to use a lar)-.275 E(ger initial sending rate.)
-.198 E F1(A.6.)72 657 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)100.8 683 Q
(ould allo)-.11 E(w)-.275 E
(connections to use higher sending rates along underutilized paths, b)
100.8 696 Q(ut that does not attempt)-.22 E(to pro)100.8 709 Q
(vide a ne)-.165 E
(xt-generation transport protocol, and does not attempt the goal of pro)
-.165 E(viding)-.165 E -.165(ve)100.8 722 S(ry 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 11.4 discusses, there are a number)-2.75 E(Flo)72 769
Q 201.583(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.6. [P)2.75 F
(age 51])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E(of proposals such as XCP)
100.8 85 Q 2.75(,M)-1.221 G
(axNet, and AntiECN for more \214ne-grained per)-2.75 E(-pack)-.22 E(et)
-.11 E(feedback from routers than the current congestion control mechan\
isms, that do attempt)100.8 98 Q(these more ambitious goals.)100.8 111 Q
(Compared to proposals such as XCP and AntiECN, Quick-Start of)100.8 137
Q(fers much less control.)-.275 E(Quick-Start does not attempt to pro)
100.8 150 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.)100.8 163 Q(Quick-Start can be thought of as an "anti-congest\
ion-control" mechanism, that is only of)100.8 176 Q(an)100.8 189 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
202 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)100.8 215 Q(ything of)-.165 E(the lik)100.8 228 Q(e.)-.11 E
(At the same time, Quick-Start w)100.8 254 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 \(e.g., XCP')
100.8 267 Q 2.75(sc)-.605 G(wnd and rtt \214elds\),)-2.75 E(and w)100.8
280 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 control).275 E 2.75
(mechanism. Thus,)100.8 293 R(Quick-Start is signi\214cantly less po)
2.75 E(werful than proposals for ne)-.275 E(w)-.275 E
(congestion control mechanisms such as XCP and AntiECN, b)100.8 306 Q
(ut as po)-.22 E(werful or more)-.275 E(po)100.8 319 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)100.8 332 Q
(yment in the current Internet.)-.11 E 1.76 -.88(We d)100.8 358 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
371 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.)100.8 384 Q(Quick-Start is)5.5 E
(inherently a rather crude tool that does not deli)100.8 397 Q -.165(ve)
-.275 G 2.75(ra).165 G(ssurances about maintaining high link)-2.75 E
(utilization and lo)100.8 410 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)100.8 423 Q(sending rate is allo)100.8 436 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)100.8 449 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.)
100.8 462 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
475 Q 1.76 -.88(We w)100.8 501 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)100.8 514 Q .33 -.165(ve a s)-.22 H
(eparate mechanism such as Quick-Start for).165 E(indicating an allo)
100.8 527 Q(wed initial sending rate, or an allo)-.275 E
(wed total sending rate after an idle or)-.275 E(underutilized period.)
100.8 540 Q(One dif)100.8 566 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)100.8 579 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)100.8 592 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)100.8 605 Q -.165(ve)-.275 G(ly rob).165 E
(ust performance in the presence of multi-path routing by using per)-.22
E(-pack)-.22 E(et)-.11 E
(feedback, where the feedback carried in a single pack)100.8 618 Q
(et is about the relati)-.11 E .33 -.165(ve i)-.275 H(ncrease or).165 E
(decrease in the rate or windo)100.8 631 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)100.8 644 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)100.8 670 Q(gi)100.8 683 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)100.8 696 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)100.8 709 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;)-2.75 E(for e)5.5 E(xample, the Quick-Start Request)-.165 E
(could ha)100.8 722 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(Flo)72 769 Q 201.583
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.6. [P)2.75 F(age 52])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E
(round-trip time are routed on path B.)100.8 85 Q(There are also dif)
100.8 111 Q
(ferences between Quick-Start and some of the proposals for per)-.275 E
(-pack)-.22 E(et)-.11 E(feedback in terms of the number of bits of feed\
back required from the routers to the end-)100.8 124 Q 2.75
(nodes. Quick-Start)100.8 137 R
(uses four bits of feedback in the rate request \214eld to indicate the)
2.75 E(allo)100.8 150 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)100.8 163 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)
100.8 176 Q(that the sender can increase as f)100.8 189 Q(ast as slo)
-.11 E(w-starting, in response to this particular pack)-.275 E(et)-.11 E
(ackno)100.8 202 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)100.8 215 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)100.8 228 Q 2.75
(ww)-.275 G(hen this pack)-2.75 E(et is ackno)-.11 E(wledged.)-.275 E
(Ho)100.8 241 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)100.8 254 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)100.8 267 Q(-)-.22 E(pack)100.8 280 Q
(et feedback to increase or decrease the sending rate.)-.11 E
(On a more practical le)100.8 306 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)100.8 319 Q
(wer open issues with Quick-Start than there w)-.275 E(ould be with a)
-.11 E(ne)100.8 332 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)100.8 345 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.)
100.8 358 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)100.8 371 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.)100.8 384 Q -.88(Ta)100.8 410 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)100.8 423 Q(et congestion control feedback.)-.11 E(Flo)72 769 Q
201.583(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.6. [P)2.75 F
(age 53])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 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(A.7.)72 559 Q/F3 13/Times-Bold@0 SF(Alter)5.5 E
(nate Implementations f)-.195 E(or a QuickStart Nonce)-.325 E F2 2.75
(A.7.1. An)72 598 R(Alter)2.75 E(nate Pr)-.165 E(oposal f)-.198 E
(or the QuickStart 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 193.333
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(A.7.1. [P)2.75 F(age 54])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 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(A.7.2. The)72
241 R(Earlier Request-A)2.75 E(ppr)-.275 E -.11(ove)-.198 G 2.75(dQ).11
G(uickStart 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(uickStart 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(uickStart 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 2.75(rt).165 G(o)-2.75 E
(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 the QS TTL \214eld, by ze\
roing 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(uickStart 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(B.)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 [KHF05] 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(B. [P)2.75 F(age 55])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(Because CCID 3 uses a rate-\
based 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: \(1\) ho)-.275 E 2.75
(wd)-.275 G(oes the sender respond if a Quick-Start pack)-2.75 E(et)-.11
E(is dropped; and \(2\) when does the sender determine that there has b\
een no feedback from)100.8 176 Q(the recei)100.8 189 Q -.165(ve)-.275 G
.88 -.44(r, a).165 H(nd reduce the sending rate?).44 E(\(1\) Ho)100.8
215 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)100.8 228 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)100.8 241 Q
(ould ha)-.11 E .33 -.165(ve u)-.22 H
(sed if the Quick-Start request had not).165 E(been appro)100.8 254 Q
-.165(ve)-.165 G(d.).165 E(\(2\) When does the sender decide there has \
been no feedback from the recei)100.8 280 Q -.165(ve)-.275 G(r:).165 E
(Unlik)100.8 293 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)100.8 306 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.)
100.8 319 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)100.8 332 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 \(when the sender is sending at least one)
-2.75 E(pack)100.8 345 Q(et e)-.11 E -.165(ve)-.275 G(ry tw).165 E 2.75
(or)-.11 G(ound-trip times\).)-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)100.8 358 Q
(al, e.g., to reduce the sending rate if no feedback is)-.275 E(recei)
100.8 371 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
(The question also arises of ho)100.8 397 Q 2.75(wt)-.275 G
(he sending rate should be reduced after a period of no)-2.75 E
(feedback from the recei)100.8 410 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)100.8 423 Q
(\214cient response to the absence of feedback; an)-.275 E(alternati)
100.8 436 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)100.8 449 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
462 Q 2.75(sr)-.605 G(esponse to a period of no)-2.75 E
(feedback from the recei)100.8 475 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)100.8 501 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)100.8 514 Q
(wing questions arise: \(1\) what rate does the)-.275 E
(sender request; \(2\) what is the response to a pack)100.8 527 Q
(et loss; and \(3\) when does the sender)-.11 E
(determine that there has been no feedback from the recei)100.8 540 Q
-.165(ve)-.275 G .88 -.44(r, a).165 H(nd the sending rate must be).44 E
(reduced?)100.8 553 Q(\(1\) What rate does the sender request:)100.8 579
Q(As in TCP)100.8 592 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.)
100.8 605 Q(The sender kno)5.5 E(ws the)-.275 E(current loss e)100.8 618
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)100.8 631 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
644 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
657 Q(because in standard operation CCID 3 does not allo)100.8 670 Q
2.75(wt)-.275 G(he sender to send more than twice as)-2.75 E -.11(fa)
100.8 683 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:)100.8 709 Q
(The response to the loss of Quick-Start pack)100.8 722 Q
(ets should be to return to the sending rate that)-.11 E(Flo)72 769 Q
210.438(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(B. [P)2.75 F
(age 56])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E -.11(wo)100.8 85 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)100.8 111 Q
-.165(ve)-.275 G(r:).165 E
(As in the case of the initial sending rate, it w)100.8 124 Q
(ould seem prudent to reduce the sending rate if)-.11 E
(no feedback is recei)100.8 137 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(that in this case, the sending rate shou\
ld be reduced to the sending rate that w)100.8 150 Q(ould ha)-.11 E
-.165(ve)-.22 G(been used if no Quick-Start request had been appro)100.8
163 Q -.165(ve)-.165 G(d.).165 E/F1 11/Times-Bold@0 SF(C.)72 202 Q/F2 14
/Times-Bold@0 SF -.28(Po)5.5 G(ssible Router Algorithm).28 E F0(This sp\
eci\214cation does not tightly de\214ne the algorithm a router uses whe\
n deciding)100.8 228 Q(whether to appro)100.8 241 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)100.8 254 R
(range of algorithms is lik)2.75 E
(ely useful in this space and we consider the algorithm)-.11 E 2.75(ap)
100.8 267 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)100.8 280 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
293 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
306 Q(xample and as a frame)-.165 E -.11(wo)-.275 G
(rk for thinking about additional mechanisms.).11 E([SAF05] pro)100.8
332 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)100.8 345 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)100.8 358 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)
100.8 371 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
384 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 \(of some).165 E
(size\).)100.8 397 Q(First, we de\214ne the "peak utilization" estimati\
on technique \(from [SAF05]\).)100.8 423 Q(This)5.5 E
(mechanism records the utilization of the link e)100.8 436 Q -.165(ve)
-.275 G(ry S seconds and stores the most recent N).165 E
(of these measurements.)100.8 449 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
462 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.)100.8 475 Q
(In [SAF05] S is set to 0.15 seconds, and)5.5 E -.165(ex)100.8 488 S
(periments use v).165 E(alues for N ranging from 3 to 20.)-.275 E
(Second, we de\214ne the "tar)100.8 514 Q
(get" algorithm for processing incoming Quick-Start Rate)-.198 E
(Requests \(also from [SAF05]\).)100.8 527 Q
(The algorithm relies on kno)5.5 E(wing the bandwidth of the)-.275 E
(outgoing link \(which in man)100.8 540 Q 2.75(yc)-.165 G
(ases can be easily con\214gured\), the utilization of the)-2.75 E
(outgoing link \(from an estimation technique such as gi)100.8 553 Q
-.165(ve)-.275 G 2.75(na).165 G(bo)-2.75 E -.165(ve)-.165 G 2.75(\)a)
.165 G(nd an estimate of the)-2.75 E
(potential bandwidth from recent Quick-Start appro)100.8 566 Q -.275(va)
-.165 G(ls.).275 E -.385(Tr)100.8 592 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)100.8 605 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 simpliest method, outlined in Section 8.2,)
5.5 E(is for the router to k)100.8 618 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
631 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)100.8 644 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.)100.8 657 Q(The e)5.5 E(xperiments in [SAF05] 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)100.8 670 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)100.8 696 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')100.8 709 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)100.8 722 Q -.275(va)-.165 G(ls,).275 E(Flo)72 769 Q 210.438
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(C. [P)2.75 F(age 57])-.165
E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(is abo)100.8 85 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 98 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)100.8 111 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)100.8 124 Q(ould not dri)
-.11 E .33 -.165(ve t)-.275 H(he utilization to more than the).165 E(gi)
100.8 137 Q -.165(ve)-.275 G 2.75(nt).165 G 2.75(hreshold. The)-2.75 F
(algorithm is:)2.75 E(util_bw = bandwidth * utilization;)106.3 163 Q
(util_bw = util_bw + recent_qs_appro)106.3 176 Q -.275(va)-.165 G(ls;)
.275 E(if \(util_bw < \(qs_thresh * bandwidth\)\))106.3 189 Q({)106.3
202 Q(appro)117.3 215 Q -.165(ve)-.165 G 2.75(d=\().165 G
(qs_thresh * bandwidth\) - util_bw;)-2.75 E(if \(rate_request < appro)
117.3 228 Q -.165(ve)-.165 G(d\)).165 E(appro)128.3 241 Q -.165(ve)-.165
G 2.75(d=r).165 G(ate_request;)-2.75 E(appro)117.3 254 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)117.3 267 Q -.275(va)-.165 G(ls += appro)
.275 E -.165(ve)-.165 G(d;).165 E(})106.3 280 Q(Also note that gi)100.8
306 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)100.8 319 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.)100.8 332 Q(Routers that wish to k)
100.8 358 Q
(eep close track of the allocated Quick-Start bandwidth could use)-.11 E
(Appro)100.8 371 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)100.8 384 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.)
100.8 397 Q/F1 11/Times-Bold@0 SF -.22(D.)72 436 S/F2 14/Times-Bold@0 SF
-.28(Po)5.72 G(ssible Additional Uses f).28 E(or the Quick-Start Option)
-.35 E F0(The Quick-Start Option contains a four)100.8 462 Q
(-bit Function \214eld in the third byte, enabling)-.22 E
(additional uses to be de\214ned for the Quick-Start Option.)100.8 475 Q
(In this section we discuss some of)5.5 E
(the possible additional uses that ha)100.8 488 Q .33 -.165(ve b)-.22 H
(een discussed for Quick-Start.).165 E(The Function \214eld)5.5 E(mak)
100.8 501 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)100.8 527 Q
(Sending Rate' codepoint set in the Function \214eld w)100.8 540 Q
(ould be using the Rate Request \214eld to)-.11 E
(report the current estimated sending rate for that connection.)100.8
553 Q(This could accompan)5.5 E 2.75(ya)-.165 G
(second Quick-Start Request in the same pack)100.8 566 Q
(et containing a standard rate request, for a)-.11 E(connection that is\
 using Quick-Start to increase its current sending rate.)100.8 579 Q(Re\
quest to Increase Sending Rate: A codepoint for `Request to Increase Se\
nding Rate' in)100.8 605 Q(the Function \214eld w)100.8 618 Q
(ould indicate that the connection is not idle or just starting up, b)
-.11 E(ut is)-.22 E
(attemmpting to use Quick-Start to increase its current sending rate.)
100.8 631 Q(This codepoint w)5.5 E(ould)-.11 E
(not change the semantics of the Rate Request \214eld.)100.8 644 Q -.66
(RT)100.8 670 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)100.8 683 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)100.8 696 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)100.8 709 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)100.8 722 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(Flo)72 769 Q 209.833
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(D. [P)2.75 F(age 58])-.165
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(September 2006)2.75 E(March 2006)106.935 E(grained encoding of the R)
100.8 85 Q(TT)-.66 E(.)-.814 E(Informational Request: An Informational \
Request codepoint in the Function \214eld w)100.8 111 Q(ould)-.11 E(ind\
icate that a request is purely informational, for the sender to \214nd \
out if a rate request)100.8 124 Q -.11(wo)100.8 137 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.)100.8 150 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
(time later by a standard Quick-Start Request.)100.8 163 Q 2.75(Ar)5.5 G
(outer appro)-2.75 E(ving an Informational Request)-.165 E -.11(wo)100.8
176 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)100.8 189 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)
100.8 202 Q(.)-.605 E(Use F)100.8 228 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)100.8 241 Q
(ould indicate that an alternate format w)-.11 E
(as being used for the Rate)-.11 E(Request \214eld.)100.8 254 Q(Do Not \
Decrement: A Do Not Decrement codepoint could be used for a Quick-Start)
100.8 280 Q(request where the sender w)100.8 293 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)100.8 306 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)100.8 319 Q(as appro)-.11 E
-.165(ve)-.165 G(d.).165 E/F1 11/Times-Bold@0 SF(E.)72 358 Q/F2 14
/Times-Bold@0 SF -.35(Fe)5.5 G(edback fr).35 E(om Bob Briscoe)-.252 E F0
([B05] in a re)100.8 384 Q(vie)-.275 E 2.75(wo)-.275 G 2.75(fa)-2.75 G
2.75(ne)-2.75 G(arlier v)-2.75 E
(ersion of the Quick-Start proposal discussed a number of)-.165 E
(potential problems with Quick-Start, and ar)100.8 397 Q
(gued for an alternate approach for policing)-.198 E(congestion in netw)
100.8 410 Q(orks using re-feedback [BJCG+05,BJS05].)-.11 E(Ho)5.5 E(we)
-.275 E -.165(ve)-.275 G .88 -.44(r, [).165 H(B05] didn').44 E(t)-.198 E
(oppose the mo)100.8 423 Q .33 -.165(ve t)-.165 H 2.75(oQ).165 G
(uick-Start to e)-2.75 E
(xperimental status as long as its applicability is made)-.165 E(clear)
100.8 436 Q(.)-.605 E F1(E.1.)72 475 Q/F3 13/Times-Bold@0 SF -.26(Po)5.5
G(tential Deployment Scenarios).26 E F0([B05] ar)100.8 501 Q
(gues that because the sender')-.198 E 2.75(st)-.605 G(rustw)-2.75 E
(orthiness is not necessarily v)-.11 E(eri\214ed, Quick-)-.165 E
(Start, if it is remain stateless, should be con\214ned to en)100.8 514
Q(vironments where e)-.44 E -.165(ve)-.275 G(ry source is).165 E 2.75
(trusted. Section)100.8 527 R(3.2 of [B05] ar)2.75 E
(gues that either \(1\) Quick-Start should be recommended for)-.198 E
(deplo)100.8 540 Q(yment only in trusted en)-.11 E
(vironments, or \(2\) Quick-Start could be recommended for)-.44 E(deplo)
100.8 553 Q(yment also in untrusted en)-.11 E(vironments, with \215o)
-.44 E 2.75(ws)-.275 G(tate required at some or all routers.)-2.75 E
(Since [B05], we ha)100.8 579 Q .33 -.165(ve a)-.22 H
(dded the Report of Appro).165 E -.165(ve)-.165 G 2.75(dR).165 G
(ate as a required part of Quick-Start,)-2.75 E(and discussed w)100.8
592 Q(ays that this could be used by routers or by traf)-.11 E
(\214c policers, if desired, to)-.275 E
(check on the use of Quick-Start by senders.)100.8 605 Q 1.76 -.88(We a)
5.5 H(lso note that senders can send at an initial).88 E(high rate e)
100.8 618 Q -.165(ve)-.275 G 2.75(ni).165 G 2.75(nt)-2.75 G
(he absence of Quick-Start, in the current netw)-2.75 E 2.75(ork; that)
-.11 F(is, in our vie)2.75 E -.715(w,)-.275 G
(Quick-Start does not change the dangers to the netw)100.8 631 Q
(ork from malicious senders.)-.11 E(Thus,)5.5 E
(while we are clearly not recommending Quick-Start for widespread deplo)
100.8 644 Q(yment in the)-.11 E(global Internet, we also don')100.8 657
Q 2.75(tf)-.198 G(eel the need to e)-2.75 E
(xplicitly restrict its deplo)-.165 E(yment to)-.11 E(en)100.8 670 Q
(vironments where e)-.44 E -.165(ve)-.275 G
(ry source is trusted, or to e).165 E(xplicitly require per)-.165 E
(-\215o)-.22 E 2.75(ws)-.275 G(tate at Quick-)-2.75 E(Start routers.)
100.8 683 Q 1.76 -.88(We a)5.5 H
(ssume that Quick-Start will only be enabled at routers if the system)
.88 E(administrators feel either that the)100.8 696 Q 2.75(yh)-.165 G
-2.475 -.22(av e)-2.75 H(suf)2.97 E(\214cient trust in senders, suf)
-.275 E(\214cient policing)-.275 E(mechanisms for checking for misbeha)
100.8 709 Q(ving nodes, or suf)-.22 E(\214cient o)-.275 E -.165(ve)-.165
G(rsite to disable Quick-).165 E
(Start if it is determined to be causisng problems..)100.8 722 Q(Flo)72
769 Q 202.804(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(E.1. [P)2.75
F(age 59])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF(E.2.)
72 85 Q/F2 13/Times-Bold@0 SF(Misbeha)5.5 E(ving Senders and Recei)-.325
E -.13(ve)-.13 G(rs).13 E F0(Some of the criticisms of Quick-Start in [\
B05] are criticisms for mechanisms that allocate)100.8 111 Q
(rates to senders, b)100.8 124 Q
(ut this is not what Quick-Start does. Quick-Start requests apply to)
-.22 E(indi)100.8 137 Q(vidual connections, not to unique addresses or \
unique tuples of addresses.)-.275 E(Further)5.5 E 2.75(,t)-.44 G(he)
-2.75 E(appro)100.8 150 Q -.275(va)-.165 G 2.75(lb).275 G 2.75(yr)-2.75
G(outers of Quick-Start requests does not result in an allocation of ba\
ndwidth)-2.75 E(for the sender making that request; the appro)100.8 163
Q -.275(va)-.165 G 2.75(lb).275 G 2.75(yr)-2.75 G
(outers does not result in an)-2.75 E 2.75(ya)-.165 G(llocation)-2.75 E
(of bandwidth at all.)100.8 176 Q
(The state used by routers from past Quick-Start appro)5.5 E -.275(va)
-.165 G(ls is used only).275 E(to guide the router in its appro)100.8
189 Q -.275(va)-.165 G 2.75(lo).275 G 2.75(rr)-2.75 G
(ejection of future Quick-Start requests.)-2.75 E 1.76 -.88(We h)5.5 H
-2.475 -.22(av e).88 H(added te)100.8 202 Q(xt to this document to mak)
-.165 E 2.75(et)-.11 G(his quite e)-2.75 E(xplicit.)-.165 E([B05] discu\
sses the dangers of sender spoo\214ng and identity splitting.)100.8 228
Q(Identify splitting)5.5 E -.11(wo)100.8 241 S(uld not be a problem wit\
h Quick-Start, because Quick-Start requests apply to indi).11 E(vidual)
-.275 E
(connections, not to unique addresses or unique tuples of addresses.)
100.8 254 Q(Because Quick-Start)5.5 E
(does not allocate rates to senders, sender)100.8 267 Q
(-spoo\214ng is also not a critical issue \(e)-.22 E(xcept as it)-.165 E
-.11(wo)100.8 280 S(uld mak).11 E 2.75(ei)-.11 G 2.75(tm)-2.75 G
(ore dif)-2.75 E
(\214cult for those Quick-Start routers that maintain per)-.275 E
(-\215o)-.22 E 2.75(ws)-.275 G(tate to)-2.75 E
(identify senders that send Quick-Start requests that are not in f)100.8
293 Q(act used, due either to)-.11 E
(malicious requests or due to requests denied do)100.8 306 Q
(wnstream\).)-.275 E(In Section 3.3, [B05] says that "the lack of a sec\
ure binding between a request and)100.8 332 Q(subsequent traf)100.8 345
Q(\214c means that an)-.275 E 2.75(yo)-.165 G(ther node could send a b)
-2.75 E(urst of traf)-.22 E(\214c and claim it)-.275 E
(requests it, with no-one being able to pro)100.8 358 Q .33 -.165(ve i)
-.165 H 2.75(td).165 G(idn')-2.75 E 2.75(t." In)-.198 F
(the current Internet, an)2.75 E 2.75(yn)-.165 G(ode can)-2.75 E
(send a b)100.8 371 Q(urst of traf)-.22 E(\214c an)-.275 E 2.75(yt)-.165
G(ime it w)-2.75 E(ould lik)-.11 E(e, e)-.11 E -.165(ve)-.275 G 2.75(nw)
.165 G(ithout Quick-Start.)-2.75 E(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G
.88 -.44(r, i).165 H 2.75(nt).44 G(he)-2.75 E
(absense of Quick-Start, sending at a high rate is not al)100.8 384 Q
-.11(wa)-.11 G(ys in the sender').11 E 2.75(si)-.605 G(nterest, as the)
-2.75 E(pack)100.8 397 Q(ets that are send might ha)-.11 E .33 -.165
(ve a h)-.22 H(igh probability of being dropped in the netw).165 E(ork,)
-.11 E(particularly in the absense of Quick-Start.)100.8 410 Q
(The addition of the Report of Appro)5.5 E -.165(ve)-.165 G 2.75(dR).165
G(ate to)-2.75 E(Quick-Start gi)100.8 423 Q -.165(ve)-.275 G 2.75(st)
.165 G(raf)-2.75 E
(\214c policers the ability to check on some of the potential ab)-.275 E
(uses of)-.22 E(Quick-Start, if the)100.8 436 Q 2.75(ys)-.165 G 2.75(od)
-2.75 G(esire.)-2.75 E
(In Section 3.8, [B05] states that "not only do Quick-Start senders ha)
100.8 462 Q .33 -.165(ve t)-.22 H 2.75(ob).165 G 2.75(et)-2.75 G
(rusted, b)-2.75 E(ut)-.22 E(also other senders who could claim their d\
ata had been authorised by a Quick-Start)100.8 475 Q
(response when it hadn')100.8 488 Q 2.75(t\()-.198 G
(Section 3.3\)." In response, we w)-2.75 E(ould ag)-.11 E
(ain clarify that with)-.055 E(Quick-Start, the Quick-Start request mak)
100.8 501 Q(es no dif)-.11 E(ference in ho)-.275 E 2.75(wt)-.275 G
(he subsequent Quick-)-2.75 E(Start data pack)100.8 514 Q
(ets are treated at the router)-.11 E 2.75(,c)-.44 G
(ompared to non-Quick-Start data pack)-2.75 E(ets.)-.11 E
(Thus, a sender')100.8 527 Q 2.75(sc)-.605 G
(laim that its data results from a pre)-2.75 E
(vious Quick-Start request should mak)-.275 E(e)-.11 E(no dif)100.8 540
Q(ference in ho)-.275 E 2.75(wt)-.275 G(hose data pack)-2.75 E
(ets are treated at routers.)-.11 E(The appro)5.5 E -.275(va)-.165 G
2.75(lo).275 G 2.75(faQ)-2.75 G(uick-)-2.75 E(Start request is not a pr\
omise by the router that the subsequent data pack)100.8 553 Q
(ets will recei)-.11 E -.165(ve)-.275 G(dif)100.8 566 Q(ferential treat\
ment at the router; it is only a statement from the router that the rou\
ter)-.275 E(belie)100.8 579 Q -.165(ve)-.275 G 2.75(st).165 G
(hat the Quick-Start data pack)-2.75 E
(ets will not change the current under)-.11 E(-utilized state of)-.22 E
(the router)100.8 592 Q 5.5(.W)-.605 G 2.75(eh)-6.38 G -2.475 -.22(av e)
-2.75 H(clari\214ed this in Section 3.3 of this document.)2.97 E F1
(E.3.)72 631 Q F2 -.325(Fa)5.5 G(ir).325 E(ness)-.195 E F0
(In its abstract, [B05] says the follo)100.8 657 Q(wing: "Because traf)
-.275 E(\214c v)-.275 E(ariance will al)-.275 E -.11(wa)-.11 G
(ys blur the).11 E(boundary)100.8 670 Q 2.75(,w)-.715 G 2.75(ea)-2.75 G
-.198(rg)-2.75 G(ue that under).198 E
(-utilisation should be treated as the e)-.22 E(xtreme of a spectrum)
-.165 E(where f)100.8 683 Q(airness is al)-.11 E -.11(wa)-.11 G
(ys an issue to some e).11 E(xtent.")-.165 E
(The speci\214cation for Quick-Start no)100.8 709 Q 2.75(ws)-.275 G
(ays the follo)-2.75 E(wing: "A router should only appro)-.275 E .33
-.165(ve a)-.165 H(Quick-Start request if the output link is underutili\
zed, and if the router judges that the)100.8 722 Q(Flo)72 769 Q 202.804
(yd/Allman/Jain/Sarolahti Section)-.11 F 2.75(E.3. [P)2.75 F(age 60])
-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E
(output link will continue to be underutilized if the request is appro)
100.8 85 Q -.165(ve)-.165 G(d.").165 E 1.76 -.88(We c)100.8 111 T(hange\
d the quote "for a mechanism for requesting an initial sending rate in \
an).88 E(underutilized en)100.8 124 Q(vironment, the f)-.44 E
(airness issues of a general congestion control mechanism)-.11 E(go a)
100.8 137 Q -.11(wa)-.165 G(y" to the follo).11 E
(wing: "because Quick-Start is a mechanism for requesting an initial)
-.275 E(sending rate in an underutilized en)100.8 150 Q
(vironment, its f)-.44 E(airness issues are less se)-.11 E -.165(ve)
-.275 G(re than those).165 E
(of a general congestion control mechanism.")100.8 163 Q(Ho)100.8 189 Q
(we)-.275 E -.165(ve)-.275 G .88 -.44(r, w).165 H 2.75(ed).44 G(id not \
add the sentence recommended in Ssection 3.4 of [B05], that "Quick-)
-2.75 E(Start is tar)100.8 202 Q(geted at an e)-.198 E(xperimental en)
-.165 E(vironment where the more intractable issues can be)-.44 E
(set aside".)100.8 215 Q(In particular)5.5 E 2.75(,w)-.44 G 2.75(ed)
-2.75 G(on')-2.75 E 2.75(ta)-.198 G
(gree that Quick-Start needs to be tar)-2.75 E(geted only for)-.198 E
(en)100.8 228 Q(vironments where f)-.44 E(airness is not an issue.)-.11
E/F1 11/Times-Bold@0 SF(E.4.)72 267 Q/F2 13/Times-Bold@0 SF
(Models of Under)5.5 E(-Utilization)-.481 E F0
([B05] states that "One of the under)100.8 293 Q
(-utilisation assumptions I had in my head while reading)-.22 E
(the paper w)100.8 306 Q(as that an)-.11 E 2.75(yo)-.165 G
(ne host is generally able to o)-2.75 E -.165(ve)-.165 G -.22(r-).165 G
(\214ll a).22 E -.275(va)-.22 G(ilable capacity).275 E 2.75(,b)-.715 G
(ut that,)-2.97 E(gi)100.8 319 Q -.165(ve)-.275 G 2.75(nah).165 G
(igh rate, the \215o)-2.75 E 2.75(ww)-.275 G(ould end quickly)-2.86 E
2.75(." W)-.715 F 2.75(ea)-.88 G
(re sorry that this is the model that the)-2.75 E
(author inferred from the draft, b)100.8 332 Q(ut we can gi)-.22 E .33
-.165(ve a)-.275 H(ssurances that this `one big \215o).165 E 2.75(wa)
-.275 G 2.75(tat)-2.75 G(ime")-2.75 E(model w)100.8 345 Q(as *ne)-.11 E
-.165(ve)-.275 G(r* the implicit or e).165 E
(xplicit model underlying the Quick-Start design.)-.165 E(\(W)5.5 E(e)
-.88 E -.11(wo)100.8 358 S(uld also note that e).11 E -.165(ve)-.275 G
(ry v).165 E(ersion of this document since the \214rst v)-.165 E
(ersion back in 2002 has)-.165 E
(discussed router responses when the router e)100.8 371 Q
(xperiences a \215ood of Quick-Start requests.\))-.165 E
([B05] also says the follo)100.8 397 Q(wing: "By re)-.275 E -.165(ve)
-.275 G(rse engineering this algorithm, it w).165 E(as possible to)-.11
E(guess that there w)100.8 410 Q(as an assumption that host capacity w)
-.11 E(as smaller than the netw)-.11 E(ork')-.11 E(s, so)-.605 E
(meeting a request in full w)100.8 423 Q(ould still lea)-.11 E .33 -.165
(ve a l)-.22 H(ot of spare capacity for the ne).165 E(xt request.")-.165
E(Ag)100.8 436 Q(ain, we w)-.055 E(ould lik)-.11 E 2.75(et)-.11 G 2.75
(oc)-2.75 G
(larify that there has been no such assumption underlying the)-2.75 E
(Quick-Start design.)100.8 449 Q F1(E.5.)72 488 Q F2
(Router Algorithms as Local P)5.5 E(olicy)-.26 E F0([B05] recommends th\
at either this document should set constraints on possible router)100.8
514 Q(algorithms, or say that e)100.8 527 Q
(xperiments are needed "in order to establish constraints required on)
-.165 E(router algorithms for interw)100.8 540 Q(orking, rob)-.11 E
(ustness, f)-.22 E(airness etc." While it is possible that)-.11 E -.165
(ex)100.8 553 S(periments will lead to an understanding of constraints \
that are needed on router).165 E(algorithms, we think it is more lik)
100.8 566 Q(ely that there will not be a need for e)-.11 E
(xplicit constraints on)-.165 E
(router algorithms for accepting or rejecting Quick-Start requests.)
100.8 579 Q(Our approach is that, while the Quick-Start IETF documentat\
ion standardizes the)100.8 605 Q(semantics of Quick-Start and the forma\
t of the Quick-Start IP Option and the Quick-Start)100.8 618 Q(Response\
 TCP Option, the IETF documentation should not and does not standardize\
 the)100.8 631 Q(algorithms used at routers for appro)100.8 644 Q
(ving or den)-.165 E(ying Quick-Start request.)-.165 E(Appendix D in)5.5
E(this document has presented one possible router algorithm for appro)
100.8 657 Q(ving or den)-.165 E(ying Quick-)-.165 E(Start requests, b)
100.8 670 Q(ut further discussion of the range of possibilities in rout\
er algorithms is)-.22 E -.22(av)100.8 683 S(ailable else)-.055 E
(where [SAF05].)-.275 E(As an e)5.5 E(xample, the f)-.165 E
(airness criteria that routers might apply)-.11 E(in granting or den)
100.8 696 Q(ying Quick-Start requests are discussed in [SAF05], b)-.165
E(ut are not discussed)-.22 E(in the same detail in this document.)100.8
709 Q(This document lea)5.5 E -.165(ve)-.22 G 2.75(sr).165 G
(outers free to apply an)-2.75 E 2.75(yc)-.165 G(riteria)-2.75 E(the)
100.8 722 Q 2.75(yc)-.165 G(hoose in accepting or den)-2.75 E
(ying Quick-Start requests, modulo the requirements gi)-.165 E -.165(ve)
-.275 G(n).165 E(Flo)72 769 Q 202.804(yd/Allman/Jain/Sarolahti Section)
-.11 F 2.75(E.5. [P)2.75 F(age 61])-.165 E 0 Cg EP
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(September 2006)2.75 E(March 2006)106.935 E(in Section 3.3 abo)100.8 85
Q -.165(ve)-.165 G(.).165 E(This approach of the Quick-Start router alg\
orithm as a matter of local polic)100.8 111 Q 2.75(yi)-.165 G 2.75(sc)
-2.75 G(onsistent)-2.75 E(with the approach in RFC 3168 on standardizin\
g Explicit Congestion Noti\214cation \(ECN\).)100.8 124 Q
(RFC 3168 standardized the semantics of the ECN \214eld, b)100.8 137 Q
(ut did not standardize a router')-.22 E(s)-.605 E(Acti)100.8 150 Q .33
-.165(ve Q)-.275 H
(ueue Management mechanisms for deciding when to set the Congestion).165
E(Experienced codepoint in pack)100.8 163 Q(ets.)-.11 E/F1 11
/Times-Bold@0 SF(E.6.)72 202 Q/F2 13/Times-Bold@0 SF(An Alter)5.5 E
(nate Pr)-.195 E(oposal)-.234 E F0([B05] proposes an alternate to Quick\
-Start where endpoints allocate rates to themselv)100.8 228 Q(es.)-.165
E([B05] ar)100.8 241 Q(gues that adding rate allocation to interior rou\
ters is not the fundamenally correct)-.198 E(direction.)100.8 254 Q
([B05] ar)100.8 280 Q(gues for an approach that associates senders with\
 their ingress attachment point,)-.198 E(with routers reporting their i\
mpairment status back to the sender [BJCG+05, BJS05].)100.8 293 Q(The)
5.5 E(source declares the impairment that it belie)100.8 306 Q -.165(ve)
-.275 G 2.75(si).165 G 2.75(tw)-2.75 G
(ill accumulate along the path, and)-2.75 E(routers ef)100.8 319 Q
(fecti)-.275 E -.165(ve)-.275 G
(ly subtract the local impairment status.).165 E
(If the sender is reporting correctly)5.5 E(,)-.715 E(and the impairmen\
t has not changed signi\214cantly from one round-trip time to the ne)
100.8 332 Q(xt, the)-.165 E(reported impairment at the e)100.8 345 Q
(gress router should be close to zero.)-.165 E/F3 14/Times-Bold@0 SF
(Normati)72 384 Q .28 -.14(ve R)-.14 H(efer).14 E(ences)-.252 E F0
([RFC793] J. Postel, T)100.8 410 Q
(ransmission Control Protocol, RFC 793, September 1981.)-.385 E
([RFC1191] Mogul, J. and S. Deering, P)100.8 436 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
([RFC2460] S. Deering and R. Hinden. Internet Protocol, V)100.8 462 Q
(ersion 6 \(IPv6\) Speci\214cation.)-1.221 E(RFC 2460, December 1998.)
100.8 475 Q([RFC2581] M. Allman, V)100.8 501 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
514 Q([RFC3168] Ramakrishnan, K.K., Flo)100.8 540 Q
(yd, S., and Black, D.)-.11 E(The Addition of Explicit)5.5 E
(Congestion Noti\214cation \(ECN\) to IP)100.8 553 Q 5.5(.R)-1.221 G
(FC 3168, Proposed Standard, September 2001.)-5.5 E
([RFC3390] M. Allman, S. Flo)100.8 579 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
592 Q([RFC3742] Flo)100.8 618 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.)100.8 631 Q F3(Inf)72
670 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.)100.8 696 Q 2.75([RFC1321] Ri)100.8 722 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 62])-.165
E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 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([RFC2246] T)100.8 267 Q 2.75(.D)-.814
G(ierks and C. Allen, The TLS Protocol, RFC 2246.)-2.75 E
([RFC2309] B. Braden, D. Clark, J. Cro)100.8 293 Q(wcroft, B. Da)-.275 E
(vie, S. Deering, D. Estrin, S. Flo)-.22 E(yd, V)-.11 E(.)-1.419 E
(Jacobson, G. Minshall, C. P)100.8 306 Q(artridge, L. Peterson, K.)-.165
E(Ramakrishnan, S. Shenk)5.5 E(er)-.11 E 2.75(,J)-.44 G(.)-2.75 E
(Wrocla)100.8 319 Q
(wski, L. Zhang, Recommendations on Queue Management and Congestion)
-.165 E -1.342 -.814(Av o)100.8 332 T
(idance in the Internet, RFC 2309, April 1998.).814 E([RFC2401] S. K)
100.8 358 Q(ent and R. Atkinson. Security Architecture for the Internet\
 Protocol. RFC)-.275 E(2401, No)100.8 371 Q -.165(ve)-.165 G(mber 1998.)
.165 E([2401bis] S. K)100.8 397 Q(ent and K. Seo, Security Architecture\
 for the Internet Protocol, internet-draft)-.275 E
(draft-ietf-ipsec-rfc2401bis-06.txt, w)100.8 410 Q
(ork-in-progress, March 2005.)-.11 E([RFC2402] S. K)100.8 436 Q
(ent and R. Atkinson. IP Authentication Header)-.275 E 2.75(.R)-.605 G
(FC 2402, No)-2.75 E -.165(ve)-.165 G(mber).165 E(1998.)100.8 449 Q
([2402bis] S. K)100.8 475 Q(ent, IP Authentication Header)-.275 E 2.75
(,i)-.44 G(nternet-draft draft-ietf-ipsec-)-2.75 E(rfc2402bis-11.txt w)
100.8 488 Q(ork-in-progress, March 2005.)-.11 E([RFC2415] K. Poduri and\
 K. Nichols. Simulation Studies of Increased Initial TCP W)100.8 514 Q
(indo)-.44 E(w)-.275 E(Size. RFC 2415. September 1998.)100.8 527 Q
([RFC2416] T)100.8 553 Q 2.75(.S)-.814 G(hepard and C. P)-2.75 E 2.75
(artridge. When)-.165 F(TCP Starts Up W)2.75 E(ith F)-.44 E(our P)-.165
E(ack)-.165 E(ets Into)-.11 E(Only Three Buf)100.8 566 Q 2.75(fers. RFC)
-.275 F(2416. September 1998.)2.75 E([RFC2463] A. Conta and S. Deering.\
 Internet Control Message Protocol \(ICMPv6\) for the)100.8 592 Q
(Internet Protocol V)100.8 605 Q
(ersion 6 \(IPv6\) Speci\214cation. RFC 2463, December 1998.)-1.221 E
([RFC2488] M. Allman, D. Glo)100.8 631 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.)100.8 644 Q
([RFC2661] W)100.8 670 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)100.8 683 T -.495(Tu)3.63 G
(nneling Protocol "L2TP", RFC 2661, August 1999.).495 E
([RFC2960] R. Ste)100.8 709 Q -.11(wa)-.275 G
(rt, et. al. Stream Control T).11 E
(ransmission Protocol. RFC 2960, October)-.385 E(2000.)100.8 722 Q(Flo)
72 769 Q 261.775(yd/Allman/Jain/Sarolahti [P)-.11 F(age 63])-.165 E 0 Cg
EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E
([RFC3124] H. Balakrishnan and S. Seshan. The Congestion Manager)100.8
85 Q 2.75(.R)-.605 G(FC 3124. June)-2.75 E(2001.)100.8 98 Q
([RFC3234] B. Carpenter and S. Brim, Middlebox)100.8 124 Q(es: T)-.165 E
(axonomy and Issues, RFC 3234,)-.88 E(February 2002.)100.8 137 Q([RFC33\
44] C. Perkins \(ed.\). IP Mobility Support for IPv4. RFC 3344, August \
2002.)100.8 163 Q([RFC3360] S. Flo)100.8 189 Q 2.75(yd. Inappropriate)
-.11 F(TCP Resets Considered Harmful.)2.75 E(RFC 3360, August)5.5 E
(2002.)100.8 202 Q([RFC3649] Flo)100.8 228 Q
(yd, S., HighSpeed TCP for Lar)-.11 E(ge Congestion W)-.198 E(indo)-.44
E(ws, RFC 3649,)-.275 E(December 2003.)100.8 241 Q
([RFC3662] R. Bless, K. Nichols, and K. W)100.8 267 Q 2.75(ehrle. A)-.88
F(Lo)2.75 E(wer Ef)-.275 E(fort Per)-.275 E(-Domain Beha)-.22 E(vior)
-.22 E(\(PDB\) for Dif)100.8 280 Q(ferentiated Services.)-.275 E
(RFC 3662, December 2003.)5.5 E
([RFC3775] D. Johnson, C. Perkins, and J. Arkk)100.8 306 Q
(o. Mobility Support in IPv6. RFC 3775,)-.11 E(June 2004.)100.8 319 Q
([RFC3819] P)100.8 345 Q 2.75(.K)-1.221 G
(arn et al., "Advice for Internet Subnetw)-2.75 E
(ork Designers", July 2004.)-.11 E([RFC3948] A. Huttunen, B. Sw)100.8
371 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)100.8 384 Q(ack)-.165 E
(ets, RFC 3948, January 2005.)-.11 E([RFC4306] Kaufman, C., "Internet K)
100.8 410 Q .33 -.165(ey E)-.275 H
(xchange \(IKEv2\) Protocol", RFC 4306,).165 E(December 2005.)100.8 423
Q([AHO98] M. Allman, C. Hayes and S. Ostermann. An e)100.8 449 Q -.275
(va)-.275 G(luation of TCP with Lar).275 E(ger)-.198 E(Initial W)100.8
462 Q(indo)-.44 E(ws. A)-.275 E(CM Computer Communication Re)-.44 E(vie)
-.275 E 1.43 -.715(w, J)-.275 H(uly 1998.).715 E([B05] B. Briscoe, Re)
100.8 488 Q(vie)-.275 E(w: Quick-Start for TCP and IP)-.275 E 2.75(,i)
-1.221 G(nternet-draft draft-briscoe-tsvwg-)-2.75 E
(quickstart-rvw-00, w)100.8 501 Q(ork-in-progress, URL)-.11 E
("http://www)100.8 514 Q(.cs.ucl.ac.uk/staf)-.715 E
(f/B.Briscoe/pubs.html", No)-.275 E -.165(ve)-.165 G(mber 2005.).165 E
([BJCG+05] Briscoe, B., Jacquet, A., Di Cairano-Gilfedder)100.8 540 Q
2.75(,C)-.44 G(., Salv)-2.75 E(atori, A., Soppera, A.,)-.275 E(and M. K)
100.8 553 Q -.11(oy)-.385 G
(abe, "Policing Congestion Response in an Internetw).11 E
(ork Using Re-Feedback",)-.11 E(SIGCOMM, August 2005.)100.8 566 Q
([BJS05] Briscoe, B., Jacquet, A., and A. Salv)100.8 592 Q
(atori, "Re-ECN: Adding Accountability for)-.275 E(Causing Congestion t\
o TCP/IP", internet-draft draft-briscoe-tsvwg-re-ecn-tcp-00.txt, w)100.8
605 Q(ork-)-.11 E(in-progress, October 2005.)100.8 618 Q
([BW97] G. Brasche and B. W)100.8 644 Q(alk)-.88 E
(e. Concepts, Services and Protocols of the ne)-.11 E 2.75(wG)-.275 G
(SM)-2.75 E(Phase 2+ General P)100.8 657 Q(ack)-.165 E
(et Radio Service. IEEE Communications Mag)-.11 E(azine, pages 94--104,)
-.055 E(August 1997.)100.8 670 Q([FF99] Flo)100.8 696 Q(yd, S., and F)
-.11 E
(all, K., Promoting the Use of End-to-End Congestion Control in the)
-.165 E(Internet, IEEE/A)100.8 709 Q(CM T)-.44 E(ransactions on Netw)
-.385 E(orking, August 1999.)-.11 E(Flo)72 769 Q 261.775
(yd/Allman/Jain/Sarolahti [P)-.11 F(age 64])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E([GP)100.8 85 Q
(AR02] A. Gurto)-1.012 E 1.43 -.715(v, M)-.165 H 2.75(.P).715 G
(assoja, O. Aalto, and M. Raitola. Multi-Layer Protocol T)-2.915 E
(racing)-.385 E(in a GPRS Netw)100.8 98 Q
(ork. In Proceedings of the IEEE V)-.11 E(ehicular T)-1.221 E
(echnology Conference \(F)-.77 E(all)-.165 E(VTC2002\), V)100.8 111 Q
(ancouv)-1.221 E(er)-.165 E 2.75(,C)-.44 G(anada, September 2002.)-2.75
E([H05] P)100.8 137 Q 2.75(.H)-1.221 G(of)-2.75 E
(fman, email, October 2005.)-.275 E(Citation for ackno)5.5 E
(wledgement purposes only)-.275 E(.)-.715 E([HKP01] M. Handle)100.8 163
Q 1.43 -.715(y, C)-.165 H 2.75(.K).715 G(reibich and V)-2.75 E 2.75(.P)
-1.419 G(axson, Netw)-2.915 E(ork Intrusion Detection: Ev)-.11 E(asion,)
-.275 E -.385(Tr)100.8 176 S(af).385 E(\214c Normalization, and End-to-\
End Protocol Semantics, Proc. USENIX Security)-.275 E(Symposium 2001.)
100.8 189 Q([Jac88] V)100.8 215 Q 2.75(.J)-1.419 G
(acobson, Congestion A)-2.75 E -.22(vo)-.814 G(idance and Control, A).22
E(CM SIGCOMM)-.44 E([JD02] Manish Jain, Constantinos Do)100.8 241 Q
(vrolis, End-to-End A)-.165 E -.275(va)-.814 G(ilable Bandwidth:).275 E
(Measurement Methodology)100.8 254 Q 2.75(,D)-.715 G
(ynamics, and Relation with TCP Throughput, SIGCOMM)-2.75 E(2002.)100.8
267 Q([K03] S. K)100.8 293 Q(unniyur)-.165 E 2.75(,")-.44 G
(AntiECN Marking: A Marking Scheme for High Bandwidth Delay)-2.75 E
(Connections", Proceedings, IEEE ICC '03, May 2003.)100.8 306 Q(URL)5.5
E("http://www)100.8 319 Q(.seas.upenn.edu/~kunniyur/".)-.715 E
([KAPS02] Rajesh Krishnan, Mark Allman, Craig P)100.8 345 Q
(artridge, James P)-.165 E 2.75(.G. Sterbenz.)-1.221 F(Explicit)2.75 E
-.385(Tr)100.8 358 S(ansport Error Noti\214cation \(ETEN\) for Error)
.385 E(-Prone W)-.22 E(ireless and Satellite Netw)-.44 E(orks.)-.11 E
-.77(Te)100.8 371 S(chnical Report No. 8333, BBN T).77 E
(echnologies, March 2002.)-.77 E(URL)5.5 E("http://www)100.8 384 Q
(.icir)-.715 E(.or)-.605 E(g/mallman/papers/".)-.198 E
([KHR02] Dina Katabi, Mark Handle)100.8 410 Q 1.43 -.715(y, a)-.165 H
(nd Charles Rohrs, Internet Congestion Control for).715 E
(Future High Bandwidth-Delay Product En)100.8 423 Q(vironments. A)-.44 E
(CM Sigcomm 2002, August 2002.)-.44 E
(URL "http://ana.lcs.mit.edu/dina/XCP/".)100.8 436 Q([KHF05] E. K)100.8
462 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
(\(DCCP\), internet draft draft-ietf-dccp-spec-11.txt, w)100.8 475 Q
(ork in progress, March 2005.)-.11 E([KK03] A. K)100.8 501 Q(uzmano)
-.165 E(vic and E. W)-.165 E 2.75(.K)-1.012 G(nightly)-2.75 E 5.5(.T)
-.715 G(CP-LP: A Distrib)-5.5 E(uted Algorithm for Lo)-.22 E(w)-.275 E
(Priority Data T)100.8 514 Q(ransfer)-.385 E 5.5(.I)-.605 G
(NFOCOM 2003, April 2003.)-5.5 E
([L05] Guohan Lu, Nonce in TCP Quick Start, draft, September 2005.)100.8
540 Q(URL)5.5 E("http://www)100.8 553 Q(.net-glyph.or)-.715 E
(g/~lgh/nonce-usage.pdf".)-.198 E
([MAF04] Alberto Medina, Mark Allman, and Sally Flo)100.8 579 Q
(yd, Measuring Interactions)-.11 E(Between T)100.8 592 Q
(ransport Protocols and Middlebox)-.385 E
(es, Internet Measurement Conference 2004,)-.165 E(August 2004.)100.8
605 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)100.8 631 Q 2.75
(yd. Measuring)-.11 F(the Ev)2.75 E(olution of)-.22 E -.385(Tr)100.8 644
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 2004.).715 E
([MaxNet] MaxNet Home P)100.8 670 Q(age, URL "http://netlab)-.165 E
(.caltech.edu/~bartek/maxnet.htm".)-.44 E([PK98] V)100.8 696 Q
(enkata N. P)-1.221 E(admanabhan and Randy H. Katz, TCP F)-.165 E
(ast Start: A T)-.165 E(echnique F)-.77 E(or)-.165 E(Speeding Up W)100.8
709 Q(eb T)-.88 E(ransfers, IEEE GLOBECOM '98, No)-.385 E -.165(ve)-.165
G(mber 1998.).165 E(Flo)72 769 Q 261.775(yd/Allman/Jain/Sarolahti [P)
-.11 F(age 65])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E([P00] Joon-Sang P)100.8 85 Q
(ark, Bandwidth Disco)-.165 E -.165(ve)-.165 G
(ry of a TCP Connection, report to John).165 E(Jeidemann, 2000, pri)
100.8 98 Q -.275(va)-.275 G(te communication.).275 E(Citation for ackno)
5.5 E(wledgement purposes only)-.275 E(.)-.715 E([PRAKS02] Craig P)100.8
124 Q(artridge, Dennis Rockwell, Mark Allman, Rajesh Krishnan, James P)
-.165 E(.G.)-1.221 E(Sterbenz. A Swifter Start for TCP)100.8 137 Q 2.75
(.T)-1.221 G(echnical Report No. 8339, BBN T)-3.52 E(echnologies, March)
-.77 E 2.75(2002. URL)100.8 150 R("http://www)2.75 E(.icir)-.715 E(.or)
-.605 E(g/mallman/papers/".)-.198 E([R)100.8 176 Q
(W03] Mattia Rossi and Michael W)-.605 E
(elzl, On the Impact of IP Option Processing, Preprint-)-.88 E
(Reihe des F)100.8 189 Q
(achbereichs Mathematik - Informatik, No. 15, October 2003.)-.165 E([R)
100.8 215 Q(W04] Mattia Rossi and Michael W)-.605 E
(elzl, On the Impact of IP Option Processing -)-.88 E -.165(Pa)8.25 G
(rt 2,).165 E(Preprint-Reihe des F)100.8 228 Q
(achbereichs Mathematik - Informatik, No. 26, July 2004.)-.165 E
([S02] Ion Stoica, pri)100.8 254 Q -.275(va)-.275 G
(te communication, 2002.).275 E(Citation for ackno)5.5 E
(wledgement purposes)-.275 E(only)100.8 267 Q(.)-.715 E([SAF05] P)100.8
293 Q(asi Sarolahti, Mark Allman, and Sally Flo)-.165 E 2.75(yd. Ev)-.11
F(aluating Quick-Start for TCP)-.275 E(.)-1.221 E(May 2005.)100.8 306 Q
(URL "http://www)5.5 E(.icir)-.715 E(.or)-.605 E(g/\215o)-.198 E
(yd/quickstart.html".)-.11 E 5.5([SGF05] Singh,)100.8 332 R
(M., Guha, S., and P)2.75 E 2.75(.F)-1.221 G
(rancis, "Utilizing spare netw)-2.75 E(ork bandwidth to)-.11 E(impro)
100.8 345 Q .33 -.165(ve T)-.165 H(CP performance", A).165 E
(CM SIGCOMM 2005 W)-.44 E(ork in Progress session , August)-.88 E
(2005, https://www)100.8 358 Q(.guha.cc/saikat/pub/sigcomm05-lo)-.715 E
(wtcp.pdf.)-.275 E
([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
(Study of TCP Quick Start with NS-2.)5.5 E
(Class Project, December 2002.)100.8 436 Q(Not publically a)5.5 E -.275
(va)-.22 G(ilable; citation for ackno).275 E(wledgement)-.275 E
(purposes only)100.8 449 Q(.)-.715 E([V02] A. V)100.8 475 Q
(enkataramani, R. K)-1.221 E(okku, and M. Dahlin.)-.385 E
(TCP Nice: A Mechanism for)5.5 E(Background T)100.8 488 Q 2.75
(ransfers. OSDI)-.385 F(2002.)2.75 E([W00] Michael W)100.8 514 Q
(elzl: PTP: Better Feedback for Adapti)-.88 E .33 -.165(ve D)-.275 H
(istrib).165 E(uted Multimedia)-.22 E(Applications on the Internet, IPC\
CC 2000 \(19th IEEE International Performance,)100.8 527 Q(Computing, A\
nd Communications Conference\), Phoenix, Arizona, USA, 20-22 February)
100.8 540 Q 2.75(2000. URL)100.8 553 R
("http://informatik.uibk.ac.at/users/c70370/research/publications/".)
2.75 E([W03] Michael W)100.8 579 Q(elzl, PMTU-Options: P)-.88 E
(ath MTU Disco)-.165 E -.165(ve)-.165 G(ry Using Options, e).165 E
(xpired)-.165 E(internet-draft draft-welzl-pmtud-options-01.txt, w)100.8
592 Q 2.75(ork-in-progress. February)-.11 F(2003.)2.75 E([ZPS00] Y)100.8
618 Q 2.75(.Z)-1.419 G(hang, V)-2.75 E 2.75(.P)-1.419 G
(axson, and S. Shenk)-2.915 E(er)-.11 E 5.5(,T)-.44 G
(he Stationarity of Internet P)-5.5 E(ath Properties:)-.165 E
(Routing, Loss, and Throughput, A)100.8 631 Q(CIRI T)-.44 E
(echnical Report, May 2000.)-.77 E([ZQK00] Y)100.8 657 Q 2.75(.Z)-1.419
G(hang, L. Qiu, and S. K)-2.75 E(esha)-.275 E 1.43 -.715(v, S)-.22 H
(peeding Up Short Data T).715 E(ransfers: Theory)-.385 E(,)-.715 E
(Architectural Support, and Simulation Results, NOSSD)100.8 670 Q 2.97
-1.485(AV 2)-.44 H(000, June 2000.)1.485 E(Flo)72 769 Q 261.775
(yd/Allman/Jain/Sarolahti [P)-.11 F(age 66])-.165 E 0 Cg EP
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/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 65.168(-DRAFT Expires:)-1.012 F
(September 2006)2.75 E(March 2006)106.935 E/F1 11/Times-Bold@0 SF -1.21
(F.)72 85 S/F2 14/Times-Bold@0 SF(IAN)6.71 E 3.5(AC)-.28 G
(onsiderations)-3.5 E F0
(Quick-Start requires an IP Option and a TCP Option.)100.8 111 Q F1
-1.21(F.)72 150 S(1.)1.21 E/F3 13/Times-Bold@0 SF(IP Option)5.5 E F0(Qu\
ick-Start requires that both an IPv4 and an IPv6 Option Number be alloc\
ated.)100.8 176 Q(The IPv4)5.5 E(Option w)100.8 189 Q(ould ha)-.11 E .33
-.165(ve a c)-.22 H
(opied \215ag of 0, a class \214eld of 00, and the assigned \214v).165 E
(e-bit option)-.165 E(number)100.8 202 Q 5.5(.T)-.605 G
(he IPv6 Option w)-5.5 E(ould ha)-.11 E .33 -.165(ve t)-.22 H
(he \214rst three bits of "001" [RFC 2460, Section 4.2],).165 E
(with the \214rst tw)100.8 215 Q 2.75(ob)-.11 G
(its indicating that the IPv6 node skip o)-2.75 E -.165(ve)-.165 G 2.75
(rt).165 G(his option and continue)-2.75 E
(processing the header if it doesn')100.8 228 Q 2.75(tr)-.198 G
(ecognize the option type, and the third bit indicating)-2.75 E
(that the Option Data may change en-route.)100.8 241 Q
(In both cases the name of the option w)100.8 267 Q
(ould be "QS - Quick-Start", with this document as)-.11 E
(the reference document.)100.8 280 Q F1 -1.21(F.)72 319 S(2.)1.21 E F3
(TCP Option)5.5 E F0
(Quick-Start also requires that a TCP Option Number be allocated.)100.8
345 Q(The Length w)5.5 E(ould be 4,)-.11 E(and the Meaning w)100.8 358 Q
(ould be "Quick-Start Request", with this document as the reference)-.11
E(document.)100.8 371 Q F2 -.7(AU)72 410 S(THORS' ADDRESSES).7 E F0
(Sally Flo)100.8 449 Q(yd)-.11 E(Phone: +1 \(510\) 666-2989)100.8 462 Q
(ICIR \(ICSI Center for Internet Research\))100.8 475 Q(Email: \215o)
100.8 488 Q(yd@icir)-.11 E(.or)-.605 E(g)-.198 E(URL: http://www)100.8
501 Q(.icir)-.715 E(.or)-.605 E(g/\215o)-.198 E(yd/)-.11 E(Mark Allman)
100.8 527 Q(ICSI Center for Internet Research)100.8 540 Q
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