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%!PS-Adobe-2.0 %%Creator: dvips 5.47 Copyright 1986-91 Radical Eye Software %%Title: overrfc.dvi %%Pages: 28 1 %%BoundingBox: 0 0 612 792 %%EndComments %%BeginProcSet: tex.pro /TeXDict 200 dict def TeXDict begin /N /def load def /B{bind def}N /S /exch load def /X{S N}B /TR /translate load N /isls false N /vsize 10 N /@rigin{ isls{[0 1 -1 0 0 0]concat}if 72 Resolution div 72 VResolution div neg scale Resolution VResolution vsize neg mul TR matrix currentmatrix dup dup 4 get round 4 exch put dup dup 5 get round 5 exch put setmatrix}N /@letter{/vsize 10 N}B /@landscape{/isls true N /vsize -1 N}B /@a4{/vsize 10.6929133858 N}B /@a3{ /vsize 15.5531 N}B /@ledger{/vsize 16 N}B /@legal{/vsize 13 N}B /@manualfeed{ statusdict /manualfeed true put}B /@copies{/#copies X}B /FMat[1 0 0 -1 0 0]N /FBB[0 0 0 0]N /nn 0 N /IE 0 N /ctr 0 N /df-tail{/nn 8 dict N nn begin /FontType 3 N /FontMatrix fntrx N /FontBBox FBB N string /base X array /BitMaps X /BuildChar{CharBuilder}N /Encoding IE N end dup{/foo 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b(Unless)17 b(w)o(e)f(pro)o(vide)h(for)e(the)114 2006 y(p)q(ossibilit)o(y)h(of)d(dealing)i(with)f(congested)g(links,)h(then)f (real-time)g(services)h(will)g(simply)g(b)q(e)f(precluded)i(in)114 2062 y(those)f(cases.)k(W)l(e)d(\014nd)g(that)e(restriction)i(unacceptable.) 68 2137 y Fb(\017)23 b Fh(\\Simple)16 b(priorit)o(y)g(is)f(su\016cien)o(t.") 114 2212 y(It)h(is)h(true)f(that)g(simply)i(giving)f(higher)g(priorit)o(y)g (to)f(real-time)h(tra\016c)e(w)o(ould)i(lead)g(to)f(adequate)g(real-)114 2269 y(time)j(service)h(at)e(some)g(times)h(and)g(under)h(some)f(conditions.) 32 b(But)18 b(priorit)o(y)i(is)f(an)g(implemen)o(tation)114 2325 y(mec)o(hanism,)d(not)g(a)g(service)i(mo)q(del.)24 b(If)16 b(w)o(e)g(de\014ne)i(the)e(service)h(b)o(y)f(means)h(of)f(a)g(sp)q(eci\014c)i (mec)o(hanism,)114 2382 y(w)o(e)13 b(ma)o(y)h(not)f(get)h(the)g(exact)g (features)g(w)o(e)g(w)o(an)o(t.)k(In)d(the)f(case)g(of)f(simple)j(priorit)o (y)l(,)e(the)g(issue)h(is)g(that)e(as)114 2438 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y(migh)o(t)h(consist)g(of)g(one)g(transp)q (ort)f(connection)j(or)d(one)h(video)h(stream)f(b)q(et)o(w)o(een)g(a)g(giv)o (en)g(host)g(pair.)20 b(It)15 b(is)h(the)0 1691 y(\014nest)h(gran)o(ularit)o (y)f(of)g(pac)o(k)o(et)f(stream)h(distinguishable)j(b)o(y)e(the)f Ff(IS)p Fh(.)f(W)l(e)h(de\014ne)i(a)e(\015o)o(w)g(to)g(b)q(e)h(simplex,)g (i.e.,)0 1747 y(to)d(ha)o(v)o(e)g(a)h(single)h(source)e(but)h(N)g (destinations.)20 b(Th)o(us,)15 b(an)f(N-w)o(a)o(y)g(teleconference)i(will)h (generally)e(require)h(N)0 1804 y(\015o)o(ws,)e(one)i(originating)g(at)e(eac) o(h)h(site.)0 1902 y(In)g(to)q(da)o(y's)f(In)o(ternet,)g(IP)h(forw)o(arding)f (is)h(completely)h(egalitarian;)f(all)h(pac)o(k)o(ets)e(receiv)o(e)h(the)g (same)f(qualit)o(y)h(of)0 1958 y(service,)f(and)f(pac)o(k)o(ets)g(are)g(t)o (ypically)h(forw)o(arded)f(using)h(a)e(strict)h(FIF)o(O)g(queueing)i (discipline.)23 b(F)l(or)12 b(in)o(tegrated)0 2015 y(services,)i(a)f(router)g (m)o(ust)g(implemen)o(t)i(an)e(appropriate)h(QoS)f(for)g(eac)o(h)h(\015o)o (w,)f(in)h(accordance)g(with)g(the)f(service)0 2071 y(mo)q(del.)36 b(The)21 b(router)e(function)j(that)d(creates)h(di\013eren)o(t)h(qualities)h (of)e(service)h(is)g(called)h(\\tra\016c)d(con)o(trol".)0 2128 y(T)l(ra\016c)f(con)o(trol)g(in)i(turn)e(is)h(implemen)o(ted)i(b)o(y)d(three) h(comp)q(onen)o(ts:)26 b(the)19 b(pac)o(k)o(et)f(sc)o(heduler,)i(the)f (classi\014er,)0 2184 y(and)c(admission)h(con)o(trol.)68 2332 y Fb(\017)23 b Fh(P)o(ac)o(k)o(et)14 b(Sc)o(heduler)114 2407 y(The)e(pac)o(k)o(et)g(sc)o(heduler)h(manages)f(the)g(forw)o(arding)g(of)f (di\013eren)o(t)i(pac)o(k)o(et)e(streams)h(using)h(a)e(set)h(of)g(queues)114 2464 y(and)18 b(p)q(erhaps)i(other)e(mec)o(hanisms)h(lik)o(e)h(timers.)30 b(The)19 b(pac)o(k)o(et)f(sc)o(heduler)i(m)o(ust)e(b)q(e)h(implemen)o(ted)i (at)114 2520 y(the)f(p)q(oin)o(t)h(where)g(pac)o(k)o(ets)e(are)h(queued;)k (this)d(is)g(the)f(output)g(driv)o(er)h(lev)o(el)h(of)e(a)g(t)o(ypical)h(op)q (erating)0 2646 y(Braden,)15 b(Clark)g(&)h(Shenk)o(er)1289 b([P)o(age)14 b(6])p eop %%Page: 7 7 bop 0 45 a Fh(RF)o(C)15 b(1633)156 b(In)o(tegrated)15 b(Services)h(in)g(the)g (In)o(ternet)f(Arc)o(hitecture:)20 b(an)c(Ov)o(erview)173 b(July)16 b(1994)114 245 y(system,)g(and)h(corresp)q(onds)g(to)f(the)h(link)i(la)o(y)o (er)d(proto)q(col.)25 b(The)17 b(details)h(of)e(the)h(sc)o(heduling)i (algorithm)114 301 y(ma)o(y)d(b)q(e)h(sp)q(eci\014c)i(to)d(the)h(particular)g (output)g(medium.)25 b(F)l(or)16 b(example,)i(the)f(output)g(driv)o(er)g (will)h(need)114 358 y(to)e(in)o(v)o(ok)o(e)i(the)f(appropriate)g(link-la)o (y)o(er)i(con)o(trols)e(when)h(in)o(terfacing)g(to)f(a)g(net)o(w)o(ork)f(tec) o(hnology)i(that)114 414 y(has)d(an)g(in)o(ternal)h(bandwidth)g(allo)q (cation)g(mec)o(hanism.)114 489 y(An)f(exp)q(erimen)o(tal)i(pac)o(k)o(et)e (sc)o(heduler)h(has)g(b)q(een)g(built)h(that)d(implemen)o(ts)j(the)e Ff(IS)g Fh(mo)q(del)h(describ)q(ed)h(in)114 546 y(Section)d(3)f(and)h ([SCZ93];)e(this)i(is)g(kno)o(wn)f(as)g(the)h(CSZ)f(sc)o(heduler)i(and)e(is)h (discussed)h(further)f(in)g(Section)114 602 y(4.)k(W)l(e)12 b(note)f(that)g(the)h(CSZ)f(sc)o(heme)i(is)f(not)f(mandatory)g(to)g (accomplish)i(our)e(service)i(mo)q(del;)g(indeed)h(for)114 659 y(parts)f(of)g(the)h(net)o(w)o(ork)e(that)h(are)h(kno)o(wn)f(alw)o(a)o (ys)g(to)g(b)q(e)i(underloaded,)g(FIF)o(O)f(will)h(deliv)o(er)g(satisfactory) 114 715 y(service.)114 790 y(There)d(is)g(another)g(comp)q(onen)o(t)g(that)f (could)i(b)q(e)f(considered)h(part)f(of)f(the)h(pac)o(k)o(et)f(sc)o(heduler)j (or)d(separate:)114 847 y(the)19 b Ff(estimator)i Fh([Jacobson91].)32 b(This)20 b(algorithm)g(is)g(used)h(to)e(measure)h(prop)q(erties)g(of)f(the)h (outgoing)114 903 y(tra\016c)g(stream,)i(to)f(dev)o(elop)h(statistics)f(that) g(con)o(trol)g(pac)o(k)o(et)g(sc)o(heduling)i(and)e(admission)i(con)o(trol.) 114 960 y(This)15 b(memo)g(will)i(consider)f(the)g(estimator)e(to)h(b)q(e)g (a)g(part)g(of)g(the)g(pac)o(k)o(et)g(sc)o(heduler.)68 1035 y Fb(\017)23 b Fh(Classi\014er)114 1110 y(F)l(or)10 b(the)h(purp)q(ose)g(of)g (tra\016c)f(con)o(trol)h(\(and)f(accoun)o(ting\),)i(eac)o(h)f(incoming)h(pac) o(k)o(et)e(m)o(ust)h(b)q(e)g(mapp)q(ed)h(in)o(to)114 1166 y(some)k Ff(class)p Fh(;)g(all)i(pac)o(k)o(ets)e(in)h(the)g(same)f(class)h(get)g(the)f (same)h(treatmen)o(t)e(from)h(the)h(pac)o(k)o(et)f(sc)o(heduler.)114 1223 y(This)c(mapping)h(is)f(p)q(erformed)h(b)o(y)f(the)g(classi\014er.)20 b(Choice)13 b(of)e(a)h(class)g(ma)o(y)g(b)q(e)g(based)h(up)q(on)f(the)h(con)o (ten)o(ts)114 1279 y(of)i(the)h(existing)h(pac)o(k)o(et)e(header\(s\))h (and/or)f(some)g(additional)j(classi\014cation)f(n)o(um)o(b)q(er)f(added)h (to)e(eac)o(h)114 1336 y(pac)o(k)o(et.)114 1411 y(A)j(class)h(migh)o(t)f (corresp)q(ond)h(to)f(a)g(broad)g(category)g(of)g(\015o)o(ws,)g(e.g.,)h(all)g (video)g(\015o)o(ws)f(or)g(all)i(\015o)o(ws)d(at-)114 1467 y(tributable)g(to)f(a)g(particular)h(organization.)23 b(On)17 b(the)f(other)g(hand,)h(a)f(class)g(migh)o(t)h(hold)g(only)g(a)f(single)114 1524 y(\015o)o(w.)33 b(A)19 b(class)h(is)h(an)e(abstraction)g(that)g(ma)o(y)g (b)q(e)i(lo)q(cal)g(to)e(a)g(particular)h(router;)h(the)f(same)f(pac)o(k)o (et)114 1580 y(ma)o(y)i(b)q(e)h(classi\014ed)h(di\013eren)o(tly)g(b)o(y)e (di\013eren)o(t)h(routers)f(along)h(the)g(path.)39 b(F)l(or)21 b(example,)i(bac)o(kb)q(one)114 1637 y(routers)12 b(ma)o(y)h(c)o(ho)q(ose)g (to)g(map)g(man)o(y)g(\015o)o(ws)f(in)o(to)h(a)g(few)h(aggregated)e(classes,) h(while)i(routers)e(nearer)g(the)114 1693 y(p)q(eriphery)l(,)j(where)g(there) f(is)h(m)o(uc)o(h)f(less)h(aggregation,)d(ma)o(y)i(use)g(a)g(separate)g (class)h(for)e(eac)o(h)h(\015o)o(w.)68 1768 y Fb(\017)23 b Fh(Admission)16 b(Con)o(trol)114 1843 y(Admission)f(con)o(trol)f(implemen)o (ts)h(the)g(decision)h(algorithm)e(that)f(a)h(router)g(or)f(host)h(uses)g(to) g(determine)114 1900 y(whether)h(a)g(new)g(\015o)o(w)g(can)h(b)q(e)f(gran)o (ted)g(the)g(requested)h(QoS)g(without)f(impacting)h(earlier)g(guaran)o (tees.)114 1956 y(Admission)f(con)o(trol)f(is)g(in)o(v)o(ok)o(ed)g(at)g(eac)o (h)g(no)q(de)h(to)e(mak)o(e)h(a)f(lo)q(cal)i(accept/reject)f(decision,)i(at)d (the)i(time)114 2013 y(a)k(host)h(requests)g(a)g(real-time)h(service)g(along) f(some)g(path)g(through)g(the)g(In)o(ternet.)35 b(The)20 b(admission)114 2069 y(con)o(trol)14 b(algorithm)g(m)o(ust)g(b)q(e)h(consisten)o(t)g(with)f (the)h(service)g(mo)q(del,)g(and)g(it)g(is)g(logically)h(part)e(of)g (tra\016c)114 2126 y(con)o(trol.)23 b(Although)17 b(there)g(are)f(still)i(op) q(en)g(researc)o(h)e(issues)h(in)h(admission)f(con)o(trol,)g(a)f(\014rst)g (cut)h(exists)114 2182 y([JCSZ92].)114 2257 y(Admission)k(con)o(trol)f(is)h (sometimes)f(confused)h(with)g Ff(p)n(olicing)e Fh(or)h Ff(enfor)n(c)n(ement) p Fh(,)f(whic)o(h)j(is)e(a)g(pac)o(k)o(et-)114 2314 y(b)o(y-pac)o(k)o(et)e 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(ation)p Fh(,)c(IEEE)343 2127 y(T)l(rans)k(on)g(Comm.,)f(V)l(ol.)i(Com-22,)d (No.)i(5,)g(Ma)o(y)f(1974.)0 2221 y([Clark88])161 b(Clark,)17 b(D.,)f Ff(The)h(Design)g(Philosophy)h(of)g(the)g(D)o(ARP)m(A)f(Internet)f (Pr)n(oto)n(c)n(ols)p Fh(,)g(A)o(CM)g(SIG-)343 2277 y(COMM)f('88,)f(August)h (1988.)0 2371 y([CSZ92])185 b(Clark,)19 b(D.,)e(Shenk)o(er,)i(S.,)f(and)g(L.) g(Zhang,)g Ff(Supp)n(orting)h(R)n(e)n(al-Time)f(Applic)n(ations)g(in)g(an)343 2427 y(Inte)n(gr)n(ate)n(d)j(Servic)n(es)f(Packet)h(Network:)31 b(A)o(r)n(chite)n(ctur)n(e)21 b(and)h(Me)n(chanisms)p Fh(,)e(Pro)q(c.)h(SIG-) 343 2484 y(COMM)15 b('92,)f(Baltimore,)h(MD,)f(August)h(1992.)0 2646 y(Braden,)g(Clark)g(&)h(Shenk)o(er)1266 b([P)o(age)14 b(26])p eop %%Page: 27 27 bop 0 45 a Fh(RF)o(C)15 b(1633)156 b(In)o(tegrated)15 b(Services)h(in)g(the)g (In)o(ternet)f(Arc)o(hitecture:)20 b(an)c(Ov)o(erview)173 b(July)16 b(1994)0 245 y([DKS89])176 b(Demers,)12 b(A.,)g(Kesha)o(v,)g(S.,)g(and)f(S.)h (Shenk)o(er.)g 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Fh(,)e(Pro-)343 849 y(ceedings)i(of)e(the)g(3rd)g(W)l(orkshop)g(on)g(V)l(ery) g(High)h(Sp)q(eed)h(Net)o(w)o(orks,)c(Marc)o(h)i(1992.)0 938 y([Jacobson91])91 b(Jacobson,)15 b(V.,)g Ff(Private)h(Communic)n(ation)p Fh(,)f(1991.)0 1026 y([JCSZ92])162 b(Jamin,)22 b(S.,)f(Shenk)o(er,)h(S.,)f (Zhang,)f(L.,)h(and)g(D.)e(Clark,)i Ff(A)o(n)f(A)n(dmission)f(Contr)n(ol)h(A) o(lgo-)343 1083 y(rithm)d(for)g(Pr)n(e)n(dictive)f(R)n(e)n(al-Time)f(Servic)n (e)p Fh(,)f(Extended)i(abstract,)e(in)i(Pro)q(c.)f(Third)h(In)o(ter-)343 1139 y(national)f(W)l(orkshop)f(on)h(Net)o(w)o(ork)e(and)i(Op)q(erating)g (System)f(Supp)q(ort)h(for)f(Digital)h(Audio)343 1196 y(and)h(Video,)f(San)h (Diego,)f(CA,)f(No)o(v.)h(1992,)e(pp.)j(73-91.)0 1284 y([P)o(arekh92])131 b(P)o(arekh,)17 b(A.,)f Ff(A)h(Gener)n(alize)n(d)f(Pr)n(o)n(c)n(essor)h (Sharing)g(Appr)n(o)n(ach)h(to)g(Flow)f(Contr)n(ol)g(in)g(Inte-)343 1341 y(gr)n(ate)n(d)f(Servic)n(es)e(Networks)p Fh(,)g(T)l(ec)o(hnical)i(Rep)q (ort)e(LIDS-TR-2089,)h(Lab)q(oratory)e(for)h(Infor-)343 1397 y(mation)h(and)h(Decision)g(Systems,)f(Massac)o(h)o(usetts)f(Institute)i(of)e (T)l(ec)o(hnology)l(,)i(1992.)0 1486 y([P)o(artridge92])84 b(P)o(artridge,)15 b(C.,)f Ff(A)i(Pr)n(op)n(ose)n(d)g(Flow)g(Sp)n(e)n (ci\014c)n(ation)p Fh(,)d(RF)o(C)h(1363,)g(BBN,)h(July)i(1992.)0 1574 y([RSVP93a])125 b(Zhang,)18 b(L.,)g(Deering,)g(S.,)g(Estrin,)g(D.,)g (Shenk)o(er,)g(S.,)g(and)g(D.)f(Zappala,)h Ff(RSVP:)g(A)g(New)343 1631 y(R)n(esour)n(c)n(e)c(R)n(eSerV)m(ation)f(Pr)n(oto)n(c)n(ol)p Fh(,)g(Accepted)h(for)e(publication)j(in)f(IEEE)g(Net)o(w)o(ork,)d(1993.)0 1719 y([RSVP93b])123 b(Zhang,)11 b(L.,)h(Braden,)f(R.,)g(Estrin,)h(D.,)e (Herzog,)h(S.,)g(and)g(S.)g(Jamin,)h Ff(R)n(esour)n(c)n(e)f(R)n(eSerV)m (ation)343 1776 y(Pr)n(oto)n(c)n(ol)16 b(\(RSVP\))f(-)h(V)m(ersion)f(1)i(F)m (unctional)e(Sp)n(e)n(ci\014c)n(ation)p Fh(,)e(W)l(ork)h(in)i(Progress,)e (1993.)0 1864 y([ST2-90])175 b(T)l(op)q(olcic,)25 b(C.,)d Ff(Exp)n(erimental) f(Internet)g(Str)n(e)n(am)g(Pr)n(oto)n(c)n(ol:)32 b(V)m(ersion)21 b(2)h(\(ST-II\))p Fh(,)c(RF)o(C)343 1921 y(1190,)c(BBN,)h(Octob)q(er)h(1990.) 0 2009 y([T)l(enet90])159 b(F)l(errari,)20 b(D.,)f(and)g(D.)f(V)l(erma,)i Ff(A)f(Scheme)h(for)g(R)n(e)n(al-Time)f(Channel)f(Establishment)h(in)343 2066 y(Wide-A)o(r)n(e)n(a)e(Networks)p Fh(,)d(IEEE)i(JSA)o(C,)f(V)l(ol.)g(8,) g(No.)f(3,)h(pp)h(368-379,)d(April)j(1990.)0 2195 y Fg(Securit)n(y)i (Considerations)114 2318 y Fh(As)g(noted)g(in)h(Section)h(2.1,)d(the)i (abilit)o(y)g(to)f(reserv)o(e)g(resources)g(will)i(create)e(a)g(requiremen)o (t)h(for)114 2374 y(authen)o(tication,)d(b)q(oth)g(of)f(users)h(requesting)h (resource)e(guaran)o(tees)h(and)g(of)f(pac)o(k)o(ets)g(that)g(claim)114 2430 y(to)d(ha)o(v)o(e)h(the)g(righ)o(t)f(to)h(use)g(those)g(guaran)o(tees.) 18 b(These)13 b(authen)o(tication)h(issues)g(are)f(not)f(otherwise)114 2487 y(addressed)j(in)h(this)g(memo,)e(but)i(are)f(for)f(further)h(study)l(.) 0 2646 y(Braden,)g(Clark)g(&)h(Shenk)o(er)1266 b([P)o(age)14 b(27])p eop %%Page: 28 28 bop 0 45 a Fh(RF)o(C)15 b(1633)156 b(In)o(tegrated)15 b(Services)h(in)g(the)g (In)o(ternet)f(Arc)o(hitecture:)20 b(an)c(Ov)o(erview)173 b(July)16 b(1994)0 245 y Fg(Authors')j(Addresses)114 380 y Fa(Bob)k(Braden)114 437 y(USC)g(Information)f(Sciences)h(Institute)114 493 y(4676)g(Admiralty)g (Way)114 550 y(Marina)g(del)g(Rey,)g(CA)h(90292)114 662 y(Phone:)f(\(310\))g (822-1511)114 719 y(EMail:)g(Braden@ISI.EDU)114 844 y(David)g(Clark)114 900 y(MIT)g(Laboratory)g(for)g(Computer)g(Science)114 957 y(545)g(Technology) g(Square)114 1013 y(Cambridge,)f(MA)i(02139-1986)114 1126 y(Phone:)f(\(617\)) g(253-6003)114 1183 y(EMail:)g(ddc@LCS.MIT.EDU)114 1357 y(Scott)g(Shenker)114 1414 y(Xerox)g(Palo)g(Alto)g(Research)g(Center)114 1470 y(3333)g(Coyote)g (Hill)g(Road)114 1527 y(Palo)g(Alto,)g(CA)h(94304)114 1640 y(Phone:)f(\(415\))g(812-4840)114 1696 y(EMail:)g(Shenker@PARC.XEROX.COM)0 2646 y Fh(Braden,)15 b(Clark)g(&)h(Shenk)o(er)1266 b([P)o(age)14 b(28])p eop %%Trailer end userdict /end-hook known{end-hook}if %%EOF