One document matched: draft-irtf-tmrg-metrics-00.ps

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(yright \(C\) The Internet Society \(2005\). All Rights Reserv)-.11 E
(ed.)-.165 E F2(Abstract)72 492.2 Q F3
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100.8 110 Q -.15(ve)-.4 G(ntions).15 E F0 11(.......................)
10.44 G F2(3)11.5 E(2. Introduction)100.8 122 Q F0 11
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115.8 146 Q 2.5(,a)-.65 G(nd Drop Rates)-2.5 E F0 11(...............)
5.29 G F2(4)11.5 E(3.1.1. Throughput)130.8 158 Q F0 11
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E(et Drop Rates)-.1 E F0 11(..................)10.02 G F2(4)11.5 E
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(.....................)4.22 G F2(8)11.5 E(Authors' Addresses)100.8 350 Q
F0 11(......................)5.05 G F2(10)6.5 E(Full Cop)100.8 362 Q
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(Intellectual Property)100.8 374 Q F0 11(......................)2.27 G
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(users of streaming media, per)100.8 550.8 Q(-pack)-.22 E
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(some users might care about the w)100.8 576.8 Q(orst-case delay)-.11 E
2.75(,o)-.715 G 2.75(ra)-2.75 G(bout the tail of the delay distrib)-2.75
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-.11 E(-based metric.)-.22 E(Some users might care about pack)100.8
645.4 Q(et drop rates only in so f)-.11 E(ar as the)-.11 E 2.75(ya)-.165
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(transfer times, while other users might care about pack)100.8 658.4 Q
(et drop rates directly)-.11 E 5.5(.O)-.715 G(ne netw)-5.5 E(ork-)-.11 E
(related reason to a)100.8 671.4 Q -.22(vo)-.22 G
(id high steady-state pack).22 E(et drop rates is to a)-.11 E -.22(vo)
-.22 G(id congestion collapse in).22 E(en)100.8 684.4 Q
(vironments containing paths with multiple congested links.)-.44 E
(In such en)5.5 E(vironments, high)-.44 E(pack)100.8 697.4 Q
(et drop rates could result in congested links w)-.11 E
(asting scarce bandwidth by carrying)-.11 E(pack)100.8 710.4 Q
(ets that will only be dropped do)-.11 E(wnstream, before being deli)
-.275 E -.165(ve)-.275 G(red to the recei).165 E -.165(ve)-.275 G -.605
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(In this section we consider response times and oscillations together)
100.8 101.6 Q 2.75(,a)-.44 G 2.75(st)-2.75 G(here are well-)-2.75 E(kno)
100.8 114.6 Q(wn tradeof)-.275 E(fs between impro)-.275 E
(ving response times and minimizing oscillations.)-.165 E(In)5.5 E(addi\
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are often quite)100.8 127.6 Q(dif)100.8 140.6 Q(ferent from the scenari\
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2.75(3.2.1. Response)72 166.6 R(to Changes)2.75 E F0(One of the k)100.8
183.2 Q .33 -.165(ey c)-.11 H
(oncerns in the design of congestion control mechanisms has been the)
.165 E(response times to sudden congestion in the netw)100.8 196.2 Q
2.75(ork. On)-.11 F(the one hand, congestion control)2.75 E(mechanisms \
should respond reasonably promptly to sudden congestion from routing or)
100.8 209.2 Q(bandwidth changes, or from a b)100.8 222.2 Q
(urst of competing traf)-.22 E 2.75(\214c. At)-.275 F
(the same time, congestion)2.75 E
(control mechanisms should not respond too se)100.8 235.2 Q -.165(ve)
-.275 G(rely to transient changes, e.g., to a sudden).165 E
(increase in delay that will dissipate in less than the connection')
100.8 248.2 Q 2.75(sr)-.605 G(ound-trip time.)-2.75 E(Ev)100.8 274.2 Q(\
aluating the response to sudden or transient changes can be of particul\
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(control [RFC 3448], and for AIMD \(Additi)100.8 300.2 Q .33 -.165(ve I)
-.275 H(ncrease Multiplicati).165 E .33 -.165(ve D)-.275 H
(ecrease\) or related).165 E(mechanisms using parameters that mak)100.8
313.2 Q 2.75(et)-.11 G(hem more slo)-2.75 E
(wly-responding that TCP [BB01,)-.275 E(BBFS01].)100.8 326.2 Q
(In addition to the responsi)100.8 352.2 Q -.165(ve)-.275 G
(ness and smoothness of aggre).165 E -.055(ga)-.165 G(te traf).055 E
(\214c, one can consider the)-.275 E(tradeof)100.8 365.2 Q
(fs between responsi)-.275 E -.165(ve)-.275 G
(ness, smoothness, and aggressi).165 E -.165(ve)-.275 G
(ness for an indi).165 E(vidual)-.275 E(connection [FHP00]. In this cas\
e smoothness can be de\214ned by the lar)100.8 378.2 Q
(gest reduction in the)-.198 E
(sending rate in one round-trip time, in a deterministic en)100.8 391.2
Q(vironment with a pack)-.44 E(et drop)-.11 E -.165(ex)100.8 404.2 S
(actly e).165 E -.165(ve)-.275 G(ry 1/p pack).165 E 2.75(ets. The)-.11 F
(responsi)2.75 E -.165(ve)-.275 G
(ness is de\214ned as the number of round-trip times).165 E
(of sustained congested required for the sender to halv)100.8 417.2 Q
2.75(et)-.165 G(he sending rate, and the)-2.75 E(aggressi)100.8 430.2 Q
-.165(ve)-.275 G(ness is de\214ned as the maximum increase in the sendi\
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(ets per second, in the absence of congestion.)-.11 E F1 2.75
(3.2.2. Minimizing)72 469.2 R(Oscillations)2.75 E F0
(One goal is that of stability)100.8 485.8 Q 2.75(,i)-.715 G 2.75(nt)
-2.75 G(erms of minimizing oscillations of queueing delay or of)-2.75 E
2.75(throughput. Scenarios)100.8 498.8 R
(illustrating oscillations are often dominated by long-li)2.75 E -.165
(ve)-.275 G(d).165 E
(connections, perhaps with a small number of changes in the le)100.8
511.8 Q -.165(ve)-.275 G 2.75(lo).165 G 2.75(fc)-2.75 G(ongestion.)-2.75
E(An orthogonal goal for some congestion control mechanisms, e.g., for \
equation-based)100.8 537.8 Q(congestion control, is to minimize the osc\
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(connection, gi)100.8 563.8 Q -.165(ve)-.275 G 2.75(na).165 G 2.75(ne)
-2.75 G -.44(nv)-2.75 G(ironment with a \214x).44 E
(ed, steady-state pack)-.165 E(et drop rate.)-.11 E(\(As is well)5.5 E
(kno)100.8 576.8 Q(wn, TCP congestion control is characterized by a pro\
nounced oscillation in the sending)-.275 E(rate, with the sender halvin\
g the sending rate in response to congestion.\))100.8 589.8 Q
(One metric for)5.5 E(the le)100.8 602.8 Q -.165(ve)-.275 G 2.75(lo).165
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(ve)-.275 G 2.75(na).165 G(bo)-2.75 E -.165(ve)-.165 G(.).165 E F1(3.3.)
72 628.8 Q F2 -.325(Fa)5.5 G(ir).325 E(ness and Con)-.195 E -.13(ve)-.52
G -.13(rg).13 G(ence).13 E F0(Another set of metrics are those of f)
100.8 645.4 Q(airness and of con)-.11 E -.165(ve)-.44 G -.198(rg).165 G
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(considered between \215o)100.8 658.4 Q
(ws of the same protocol, and between \215o)-.275 E(ws using dif)-.275 E
(ferent)-.275 E(protocols \(e.g., f)100.8 671.4 Q
(airness between TCP and a ne)-.11 E 2.75(wt)-.275 G
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(ferent f)-.275 E(airness measures.)-.11 E(These include max-min f)5.5 E
(airness)-.11 E([HG86], proportional f)100.8 710.4 Q
(airness [KMT98, K01], the f)-.11 E(airness inde)-.11 E 2.75(xp)-.165 G
(roposed in [JCH84], and)-2.75 E(the product measure, a v)100.8 723.4 Q
(ariant of netw)-.275 E(ork po)-.11 E(wer [BJ81].)-.275 E(Flo)72 769 Q
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100.8 98 Q(ge as possible. Gi)-.198 E -.165(ve)-.275 G 2.75(nt).165 G
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(Thus, the max-min f)5.5 E(airness gi)-.11 E -.165(ve)-.275 G 2.75(sa)
.165 G(bsolute priority)-2.75 E(to the smallest \215o)100.8 124 Q(ws.)
-.275 E(Epsilon-f)100.8 150 Q(airness: A metric related to max-min f)
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(allocation is de\214ned as epsilon-f)100.8 163 Q(air if)-.11 E
(min_i x_i / max_i x_i >= 1 - epsilon.)109.05 189 Q
(where x_i is the resource allocation to the i-th user)100.8 215 Q 5.5
(.E)-.605 G(psilon-f)-5.5 E(airness measures the w)-.11 E(orst-)-.11 E
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(airness: In contrast, an allocation x is de\214ned as proportionally f)
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2.75(xr)-.165 G(anges from 0 to 1, and is maximum when all)-2.75 E
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(resource, and the other n-k users recei)100.8 423 Q .33 -.165(ve z)
-.275 H(ero allocation.).165 E(The product measure: The product measure)
100.8 449 Q(product_i x_i ,)109.05 475 Q
(the product of the throughput of the indi)100.8 501 Q
(vidual connections, is also used as a measure of)-.275 E -.11(fa)100.8
514 S 2.75(irness. F).11 F
(or our purposes, let x_i be the throughput for the i-th connection.)
-.165 E(\(In other)5.5 E(conte)100.8 527 Q(xts x_i is tak)-.165 E
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(referred to as netw)100.8 540 Q(ork po)-.11 E(wer)-.275 E 2.75(.\) The)
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-.275 H 2.75(os).165 G -.165(eg)-2.75 G(re).165 E -.055(ga)-.165 G
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-.165 G(onnection recei)-2.75 E -.165(ve)-.275 G 2.75(sz).165 G
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(measure is maximized when all connections recei)100.8 579 Q .33 -.165
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(irness and the number of congested links: Some of these f).165 E
(airness metrics are discussed in)-.11 E(more detail in [F91].)100.8 618
Q 1.76 -.88(We n)5.5 H
(ote that there is not a clear consensus for the f).88 E
(airness goals, in)-.11 E(particular for f)100.8 631 Q
(airness between \215o)-.11 E(ws that tra)-.275 E -.165(ve)-.22 G
(rse dif).165 E(ferent numbers of congested links)-.275 E([F91].)100.8
644 Q -.165(Fa)100.8 670 S
(irness and round-trip times: One goal cited in a number of ne).165 E
2.75(wt)-.275 G(ransport protocols has)-2.75 E(been that of f)100.8 683
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(orking community about the desirability of)-.11 E(this goal, or about \
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100.8 709 Q([FJ92] \(Section 3.3\).)100.8 722 Q(Flo)72 769 Q 309.141
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(airness issue is that of the relati)-.11 E .33 -.165(ve f)-.275 H
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(he same sending rate in bytes per second as a lar).165 E(ge-pack)-.198
E(et TCP connection in the)-.11 E(same en)100.8 150 Q
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(he same sending rate in *pack).165 E(ets* per second?)-.11 E(This f)
100.8 163 Q(airness issue has been discussed in more detail in [FK04], \
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(xisting \215o)-.165 E 2.75(wa)-.275 G(nd a ne)-2.75 E
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100.8 280 Q -.165(ve)-.44 G -.198(rg).165 G(ence times is the delta-f)
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(While congestion control mechanisms are generally e)100.8 400.6 Q -.275
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(ork of tw)-.11 E(o-w)-.11 E(ay point-to-point links, some en)-.11 E
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-.11 E(ariable bandwidth, mobility\) as well)-.275 E(as ne)100.8 439.6 Q
2.75(wm)-.275 G(etrics to be considered \(e.g., ener)-2.75 E
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(xplored for paths with)-.165 E(reordering, corruption, v)100.8 478.6 Q
(ariable bandwidth, asymmetric routing, router con\214guration)-.275 E
(changes, mobility)100.8 491.6 Q 2.75(,a)-.715 G(nd the lik)-2.75 E 2.75
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-.275 E(ustness o)-.22 E -.165(ve)-.165 G(r).165 E(ef)100.8 504.6 Q
(\214cienc)-.275 E 1.43 -.715(y, e)-.165 H(.g., when there are tradeof)
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Q .33 -.165(ey m)-.11 H(etric that is af).165 E
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Q(or wireless netw)-.165 E
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100.8 608.6 Q(\214cient use of the radio spectrum and lo)-.275 E
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(Rob)5.5 E(ustness to F)-.26 E(ailur)-.325 E(es and to Misbeha)-.234 E
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(One goal is for congestion control mechanisms to be rob)100.8 651.2 Q
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-.165(ve)-.275 G(rs that `lie' to data senders about the congestion e)
.165 E(xperienced along the path or)-.165 E(otherwise attempt to bypass\
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(A99].)-1.32 E
(Another goal is for congestion control mechanisms to be as rob)100.8
690.2 Q(ust as possible to f)-.22 E(ailures,)-.11 E(such as f)100.8
703.2 Q(ailures of routers in using e)-.11 E
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(One metric for congestion control mechanisms is their deplo)100.8 101.6
Q(yability in the current Internet.)-.11 E(Metrics related to deplo)
100.8 114.6 Q(yability include the ease of f)-.11 E
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(terms of pack)100.8 127.6 Q(et header size or added comple)-.11 E
(xity at end-nodes or routers.)-.165 E F1(3.7.)72 166.6 Q F2(Metrics f)
5.5 E(or Speci\214c T)-.325 E(ypes of T)-.962 E(ransport)-.962 E F0
(In some cases modi\214ed metrics are needed for e)100.8 183.2 Q -.275
(va)-.275 G(luting transport protocols intended for).275 E
(QoS-enabled en)100.8 196.2 Q(vironments or for belo)-.44 E(w-best-ef)
-.275 E(fort traf)-.275 E(\214c [VKD02, KK03].)-.275 E F1(4.)72 222.2 Q
/F3 14/Times-Bold@0 SF(Comments on Methodology)5.5 E F0(The types of sc\
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meters)100.8 238.8 Q(that it is useful to consider)100.8 251.8 Q 2.75
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-2.75 E(speci\214c scenarios for use in e)100.8 264.8 Q -.275(va)-.275 G
(luating congestion control mechanisms.).275 E 1.76 -.88(We n)100.8
281.4 T(ote that it can be important to e).88 E -.275(va)-.275 G
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(with a range of link bandwidths, congestion le)100.8 294.4 Q -.165(ve)
-.275 G(ls, and le).165 E -.165(ve)-.275 G(ls of statistical multiple)
.165 E 2.75(xing. It)-.165 F(is also important to e)100.8 307.4 Q -.275
(va)-.275 G
(luate congestion control mechanisms in a range of scenarios,).275 E(in\
cluding typical ranges of connection sizes and round-trip times [FK02].\
 It is also useful)100.8 320.4 Q(to compare metrics for ne)100.8 333.4 Q
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(More general references on methodology include [J91].)100.8 372.4 Q F1
(5.)72 398.4 Q F3(Security Considerations)5.5 E F0
(There are no security considerations in this document.)100.8 415 Q F1
(6.)72 441 Q F3(IAN)5.5 E 3.5(AC)-.28 G(onsiderations)-3.5 E F0
(There are no IAN)100.8 457.6 Q 2.75(Ac)-.385 G
(onsiderations in this document.)-2.75 E F1(7.)72 483.6 Q F3(Ackno)5.5 E
(wledgements)-.14 E F0(Thanks to Doug Leith for feedback.)100.8 500.2 Q
F3(Inf)72 526.2 Q(ormati)-.35 E .28 -.14(ve R)-.14 H(efer).14 E(ences)
-.252 E F0([BB01] D. Bansal and H. Balakrishnan, Binomial Congestion Co\
ntrol Algorithms, IEEE)100.8 542.8 Q(Infocom, April 2001.)129.6 555.8 Q
([BBFS01] D. Bansal, H. Balakrishnan, S. Flo)100.8 572.4 Q
(yd, and S. Shenk)-.11 E(er)-.11 E 2.75(,D)-.44 G(ynamic Beha)-2.75 E
(vior of)-.22 E(Slo)129.6 585.4 Q(wly-Responsi)-.275 E .33 -.165(ve C)
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(pproach to Performance-Oriented Flo).275 E(w)-.275 E(Control, IEEE T)
129.6 615 Q(ransactions on Communications, V)-.385 E
(ol.COM-29 N.4, April 1981.)-1.419 E([F91] S. Flo)100.8 631.6 Q
(yd, Connections with Multiple Congested Gate)-.11 E -.11(wa)-.275 G
(ys in P).11 E(ack)-.165 E(et-Switched)-.11 E(Netw)129.6 644.6 Q(orks P)
-.11 E(art 1: One-w)-.165 E(ay T)-.11 E(raf)-.385 E
(\214c, Computer Communication Re)-.275 E(vie)-.275 E 1.43 -.715(w, V)
-.275 H(ol.21, No.5,)-.704 E(October 1991, p. 30-47.)129.6 657.6 Q
([FK05] S. Flo)100.8 674.2 Q(yd and E. K)-.11 E(ohler)-.385 E 2.75(,T)
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(ariant, draft-ietf-dccp-tfrc-)-1.221 E -.22(vo)129.6 687.2 S
(ip-02.txt, internet draft, w).22 E(ork in progress, July 2005.)-.11 E
([FHP00] S. Flo)100.8 703.8 Q(yd, M. Handle)-.11 E 1.43 -.715(y, a)-.165
H(nd J. P).715 E(adh)-.165 E(ye, A Comparison of Equation-Based and)
-.055 E(AIMD Congestion Control, May 2000.)129.6 716.8 Q
(URL "http://www)8.25 E(.icir)-.715 E(.or)-.605 E(g/tfrc/".)-.198 E(Flo)
72 769 Q 366.891(yd [P)-.11 F(age 8])-.165 E 0 Cg EP
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(\214c Phase Ef)-.275 E(fects in P)-.275 E(ack)-.165 E(et-Switched Gate)
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(orking: Research and Experience, V)-.11 E
(.3 N.3, September 1992, p.115-156.)-1.419 E([FK04] S. Flo)100.8 114.6 Q
(yd and J. K)-.11 E(empf, IAB Concerns Re)-.275 E -.055(ga)-.165 G
(rding Congestion Control for V).055 E(oice)-1.419 E -.385(Tr)129.6
127.6 S(af).385 E(\214c in the Internet, RFC 3714, March 2004.)-.275 E
([FK02] S. Flo)100.8 144.2 Q(yd and E. K)-.11 E(ohler)-.385 E 2.75(,I)
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(2002.)129.6 157.2 Q([GF04] A. Gurto)100.8 173.8 Q 2.75(va)-.165 G
(nd S. Flo)-2.75 E(yd, Modeling W)-.11 E(ireless Links for T)-.44 E
(ransport Protocols, A)-.385 E(CM)-.44 E
(CCR, 34\(2\):85-96, April 2004.)129.6 186.8 Q
([HG86] E. Hahne and R. Gallager)100.8 203.4 Q 2.75(,R)-.44 G
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(ontrol in Data)-2.75 E(Communications Netw)129.6 216.4 Q
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(June 1986.)129.6 229.4 Q
([J91] R. Jain, The Art of Computer Systems Performance Analysis: T)
100.8 246 Q(echniques for)-.77 E
(Experimental Design, Measurement, Simulation, and Modeling, John W)
129.6 259 Q(ile)-.44 E 2.75(y&S)-.165 G(ons,)-2.75 E(1991.)129.6 272 Q
([JCH84] R. Jain, D.M. Chiu, and W)100.8 288.6 Q 2.75(.H)-1.012 G -.165
(aw)-2.75 G(e, A Quantitati).165 E .33 -.165(ve M)-.275 H(easure of F)
.165 E(airness and)-.165 E(Discrimination for Resource Allocation in Sh\
ared Systems, DEC TR-301, Littleton,)129.6 301.6 Q
(MA: Digital Equipment Corporation, 1984.)129.6 314.6 Q([K01] F)100.8
331.2 Q 2.75(.K)-.88 G(elly)-3.025 E 2.75(,M)-.715 G
(athematical Modelling of the Internet, "Mathematics Unlimited - 2001)
-2.75 E(and Be)129.6 344.2 Q(yond" \(Editors B. Engquist and W)-.165 E
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-1.221 E(685-702, 2001.)129.6 357.2 Q([KHR02] D. Katabi, M. Handle)100.8
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(nd C. Rohrs, Congestion Control for High Bandwidth-).715 E
(Delay Product Netw)129.6 386.8 Q(orks, A)-.11 E(CM Sigcomm, 2002.)-.44
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([KMT98] F)100.8 433 Q 2.75(.K)-.88 G(elly)-3.025 E 2.75(,A)-.715 G 2.75
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(airness and Stability)-.165 E 5.5(.J)-.715 G(ournal of the Operational)
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(TT Bell Laboratories report, April 1990.)-1.221 E
([RFC 2119] S. Bradner)100.8 505.2 Q 2.75(.K)-.605 G .33 -.165(ey W)
-3.025 H(ords F)-.715 E(or Use in RFCs to Indicate Requirement Le)-.165
E -.165(ve)-.275 G(ls. RFC).165 E(2119.)129.6 518.2 Q([RFC 2434] T)100.8
534.8 Q 2.75(.N)-.814 G(arten and H. Alv)-2.75 E 2.75
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(onsiderations)-2.75 E(Section in RFCs.)129.6 547.8 Q(RFC 2434.)5.5 E
([RFC 2581] M. Allman, V)100.8 564.4 Q 2.75(.P)-1.419 G(axson, and W)
-2.915 E 2.75(.S)-1.012 G(te)-2.75 E -.165(ve)-.275 G 2.75(ns. TCP).165
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FC 3448, Proposed Standard, January 2003.)129.6 594 Q
([SLFK03] R.N. Shorten, D.J. Leith, J. F)100.8 610.6 Q -.11(oy)-.165 G
2.75(,a)-.605 G(nd R. Kilduf)-2.75 E(f, Analysis and Design of)-.275 E
(Congestion Control in Synchronised Communication Netw)129.6 623.6 Q
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(Communications Re)129.6 666.2 Q(vie)-.275 E 1.43 -.715(w, O)-.275 H
(ctober 1999.).715 E([TM02] V)100.8 682.8 Q 2.75(.T)-1.419 G(saoussidis\
 and I. Matta, Open Issues of TCP for Mobile Computing, Journal of)-2.75
E -.44(Wi)129.6 695.8 S
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(ansport Protocols for Mobile Computing, February 2002.).385 E(Flo)72
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E([YL00] Y)100.8 157.2 Q 2.75(.R)-1.419 G 2.75(.Y)-2.75 G
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(TR-00-09, Department of Computer Sciences, UT Austin, May 2000.)129.6
170.2 Q([ZKL04] Y)100.8 186.8 Q 2.75(.Z)-1.419 G
(hang, S.-R. Kang, and D. Loguino)-2.75 E 1.43 -.715(v, D)-.165 H
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F1(Full Copyright Statement)72 333.4 Q F0(Cop)100.8 350 Q
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