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ENC0/Courier RE/Times-Italic@0 ENC0/Times-Italic RE/Times-Roman@0 ENC0/Times-Roman RE/Times-Bold@0 ENC0/Times-Bold RE/Courier-Bold@0 ENC0/Courier-Bold RE%%EndProlog%%Page: 1 1%%BeginPageSetupBP%%EndPageSetup/F0 10/Courier-Bold@0 SF(Internet Engineering Task Force)72 85 Q(PIM WG)209.999 E 245.999(INTERNET-DRAFT Bill)72 98 R(Fenner/AT&T)6 E 161.999(draft-ietf-pim-sm-bsr-03.ps Mark)72 111 R(Handley/ICIR)6 E(Roger Kermode/Motorola)371.999 124 Q(David Thaler/Microsoft)371.999 137Q(25 February 2003)407.999 150 Q(Expires: August 2003)383.999 163 Q/F114/Times-Bold@0 SF(Bootstrap Router \(BSR\) Mechanism f)112.615 188 Q(or PIM Sparse Mode)-.35 E/F2 11/Times-Bold@0 SF(Status of this Document)72 233 Q/F3 11/Times-Roman@0 SF(This document \is an Internet-Draft and is in full conformance with all pro)72 249.6 Q(visions of Section 10 of)-.165 E(RFC2026.)72 262.6 Q(Internet-Drafts are w)72 288.6 Q(orking documents of the Internet Engineering T)-.11 E(ask F)-.88 E(orce \(IETF\), its areas,)-.165 E(and its w)72 301.6 Q(orking groups.)-.11 E(Note that other groups may also distrib)5.5 E(ute w)-.22 E(orking documents as)-.11 E(Internet-Drafts.)72 314.6 Q(Internet-Drafts are draft documents v)72 340.6 Q(alid for a maximum of six months and may be updated,)-.275 E(replaced, or obsoleted by other documents at an)72 353.6 Q 2.75(yt)-.165 G 2.75(ime. It)-2.75 F(is inappropriate to use Internet- Drafts)2.75 E(as reference material or to cite them other than as "w)72 366.6 Q(ork in progress.")-.11 E(The list of current Internet-Drafts can be accessed at http://www)72392.6 Q(.ietf.or)-.715 E(g/ietf/1id-abstracts.txt)-.198 E(The list of Internet-Draft Shado)72 418.6 Q 2.75(wD)-.275 G(irectories can be accessed at http://www)-2.75 E(.ietf.or)-.715 E(g/shado)-.198 E -.715(w.)-.275 G(html.).715 E(This document is a product of the IETF PIM WG.)72 444.6 Q(Comments should be addressed to the authors,)5.5 E(or the WG')72 457.6Q 2.75(sm)-.605 G(ailing list at pim@catarina.usc.edu.)-2.75 E F2(Abstract)267.534 476.6 Q F3(This document speci\214es the Bootstrap Ro\uter \(BSR\) mechanism for Protocol)97 499.2 Q(Independent Multicast - Sparse Mode \(PIM-SM\).)97 512.2 Q(BSR is one w)5.5 E(ay that a PIM-SM)-.11 E(router can learn the set of\ group-to-RP mappings required in order to function.)97 525.2 Q(The)5.5E(mechanism is dynamic, lar)97 538.2 Q(gely self-con\214guring, and rob)-.198 E(ust to router f)-.22 E(ailure.)-.11 E(Fenner/Handle)72 769 Q(y/K)-.165 E 246.265(ermode/Thaler [P)-.275 F(age 1])-.165 E EP%%Page: 2 2%%BeginPageSetupBP%%EndPageSetup/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 72.802(-DRAFT Expires:)-1.012 F(August 2003)2.75 E(February 2003)103.569 E/F1 13/Times-Bold@0 SF -1.196(Ta)239.126 85 S(ble of Contents)1.196 E/F2 10/Times-Roman@0 SF(1. Introduction)97 123 Q F0 11(......................)3.56 G F2(3)11.5E(1.1. General Ov)107 135 Q(ervie)-.15 E 2.5(wa)-.25 G(nd Background)-2.5 E F0 11(..............)4 G F2(3)11.5 E(1.2. Ov)107 147 Q(ervie)-.15E 2.5(wo)-.25 G 2.5(fB)-2.5 G(ootstrap and RP Disco)-2.5 E -.15(ve)-.15G(ry for Global Scope).15 E F0 11(.......)4.71 G F2(5)11.5 E(1.3. Administrati)107 159 Q -.15(ve)-.25 G(ly Scoped Multicast and BSR).15 E F0 11(...........)8.81 G F2(5)11.5 E(2. BSR State and T)97 171 Q(imers)-.35 E F0 11(...................)5.43 G F2(6)11.5 E(3. Bootstrap Router Election and RP-Set Distrib)97 183 Q(ution)-.2 E F011(...........)1.39 G F2(7)11.5 E(3.1. Sending Candidate-RP-Adv)107 195Q(ertisements)-.15 E F0 11(.............)1.91 G F2(15)6.5 E(3.2. Creating the RP-Set at the BSR)107 207 Q F0 11(...............)5.91 G F2(15)6.5 E(3.3. F)107 219 Q(orw)-.15 E(arding Bootstrap Messages)-.1 E F0 11(...............)2.57 G F2(16)6.5E(3.4. Recei)107 231 Q(ving and Using the RP-Set)-.25 E F0 11(...............)2.56 G F2(16)6.5 E(4. Message F)97 243 Q(ormats)-.15 EF0 11(....................)10.38 G F2(17)6.5 E(4.1. Bootstrap Message F)107 255 Q(ormat)-.15 E F0 11(................)10.38 G F2(18)6.5 E(4.1.1. Semantic Fragmentation of BSMs)117 267 Q F0 11(.............)5.36 G F2(21)6.5 E(4.2. Candidate-RP-Adv)107 279 Q(ertisement F)-.15 E(ormat)-.15 E F0 11(.............)9.84 G F2(22)6.5 E(5. Def)97 291 Q(ault V)-.1 E(alues for T)-1.11 E(imers)-.35 E F0 11(..................)4.31 G F2(23)6.5 E(6. Security Considerations)97 303 Q F0 11(..................)12.17 G F2(24)6.5 E(6.1. Possible Threats)107 315 QF0 11(...................)10.92 G F2(24)6.5 E(6.2. Limiting Third-P)107327 Q(arty DoS Attacks)-.15 E F0 11(..............)8.15 G F2(24)6.5 E(6.3. BS Message Security)107 339 Q F0 11(..................)4.95 G F2(24)6.5 E(6.4. C-RP-Adv)107 351 Q(ertisement Security)-.15 E F0 11(...............)11.63 G F2(25)6.5 E(6.5. Denial of Service using IPsec)107 363 Q F0 11(...............)13.44 G F2(26)6.5 E(7. Authors' Addresses)97 375 Q F0 11(....................)1.35 G F2(26)6.5 E(8. References)97 387 Q F0 11(......................)8.58 G F2(27)6.5 E(9. Ackno)97 399 Q(wledgments)-.25 E F0 11(....................)5.76 G F2(27)6.5 E F1(List of Figur)247.674 451 Q(es)-.234 E F2(Figure 1. Per)97 489 Q(-Scope-Zone State-machine for a candidate BSR)-.2 E F0 11(........)9.08 G F2(7)11.5 E(Figure 2. Per)97 501 Q(-Scope-Zone State-machine for a router not con\214gured as C-BSR)-.2 EF0 11(...)10.89 G F2(10)6.5 E F0(Fenner/Handle)72 769 Q(y/K)-.165 E246.265(ermode/Thaler [P)-.275 F(age 2])-.165 E EP%%Page: 3 3%%BeginPageSetupBP%%EndPageSetup/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 72.802(-DRAFT Expires:)-1.012 F(August 2003)2.75 E(February 2003)103.569 E/F1 11/Times-Bold@0 SF(1.)7285 Q/F2 14/Times-Bold@0 SF(Intr)5.5 E(oduction)-.252 E F0(Note: this document assumes f)72 101.6 Q(amiliarity with the w)-.11 E(orkings of Protocol Independent Multicast -)-.11 E(Sparse Mode, as de\214ned in [3], and with Administrati)72 114.6 Q-.165(ve)-.275 G(ly Scoped Multicast, as described in [6].).165 E -.165(Fo)72 131.2 S 2.75(rc).165 G(orrect operation, e)-2.75 E -.165(ve)-.275G(ry PIM Sparse-mode router within a PIM domain must be able to map a).165 E(particular global-scope multicast group address to the same RP)72144.2 Q 5.5(.I)-1.221 G 2.75(ft)-5.5 G(his is not the case then black)-2.75 E(holes may appear)72 157.2 Q 2.75(,w)-.44 G(here some recei)-2.75E -.165(ve)-.275 G(rs in the domain cannot recei).165 E .33 -.165(ve s)-.275 H(ome groups.).165 E 2.75(Ad)5.5 G(omain in)-2.75 E(this conte)72170.2 Q(xt is a contiguous set of routers that all implement PIM and ar\e con\214gured to operate)-.165 E(within a common boundary de\214ned by\ PIM Multicast Border Routers \(PMBRs\). PMBRs connect)72 183.2 Q(each PIM domain to the rest of the internet.)72 196.2 Q 2.75(AP)72212.8 S(IM domain may also brok)-2.75 E(en up into multiple administrati)-.11 E .33 -.165(ve s)-.275 H(cope re).165 E(gions - these are re)-.165 E(gions)-.165 E(where a border has be\en con\214gured so that a range of multicast groups will not be forw)72225.8 Q(arded)-.11 E(across that border)72 238.8 Q 5.5(.F)-.605 G(or more information on Administrati)-5.665 E -.165(ve)-.275 G(ly Scoped IP Multicast, see RFC).165 E 2.75(2365. The)72 251.8 R(modi\214ed criteria for admin-scoped re)2.75 E(gions are that the re)-.165 E(gion is con)-.165 E .33 -.165(vex w)-.44 H(ith respect to).165 E(forw)72 264.8 Q(arding based on the MRIB, and that all PIM routers wit\hin the same scope re)-.11 E(gion map a)-.165 E(particular scoped group to the same RP within that re)72 277.8 Q(gion.)-.165 E(The PIM-SM speci\214cation does not mandate the use of a single\ mechanism to pro)72 294.4 Q(vide routers)-.165 E(with the information to perform the group-to-RP mapping.)72 307.4 Q(This document describes the)5.5 E(Bootstrap Router \(BSR\) mechanism.)72 320.4 Q(BSR w)5.5 E(as \214rst de\214ned in RFC 2362 [2], which has since)-.11 E(been obsoleted.)72 333.4 Q(This document pro)5.5 E(vides an updated speci\214cation of the BSR mechanism from)-.165 E(RFC 2362, and also e)72 346.4 Q(xtends it to cope with administrati)-.165 E -.165(ve)-.275 G(ly scoped re).165 E(gion boundaries.)-.165 E F1(1.1.)72 372.4 Q/F3 13/Times-Bold@0 SF(General Ov)5.5 E(er)-.13 E(view and Backgr)-.13 E(ound)-.234 E F0(Ev)72 389 Q(ery PIM-SM multicas\t group needs to be associated with the IP address of a Rendezv)-.165 E(ous-Point)-.22 E 2.75(\(RP\). When)72 402 R 2.75(an)2.75 G .55 -.275(ew m)-2.75 H(ulticast sender starts sending, its local Designated Rout\er \(DR\) will).275 E(encapsulate these data pack)72 415 Q(ets in a PIM Re)-.11 E(gister message and send them to the RP for that)-.165 E(multicast group.)72 428 Q(When a ne)5.5 E 2.75(wm)-.275 G(ulticast recei)-2.75 E -.165(ve)-.275 G 2.75(rj).165 G(oins, its local DR will send a PIM Join message)-2.75 E(to)72 441 Q-.11(wa)-.275 G(rds the RP for that multicast group.).11 E(When an)5.5 E2.75(yP)-.165 G(IM router sends a \(*,G\) Join message, it)-2.75 E(needs to kno)72 454 Q 2.75(ww)-.275 G(hich is the ne)-2.75 E(xt ho)-.165 E 2.75(wr)-.275 G(outer to)-2.75 E -.11(wa)-.275 G(rds the RP for G to send the message to.).11 E(Also)5.5 E(when a PIM router is forw)72 467 Q(arding data pack)-.11 E(ets using \(*,G\) state, it needs to kno)-.11 E 2.75(ww)-.275 G(hich is the)-2.75 E(correct incoming interf)72 480 Q(ace for pack)-.11E(ets destined for G, as it needs to reject an)-.11 E 2.75(yp)-.165 G(ack)-2.75 E(ets that arri)-.11 E -.165(ve)-.275 G(on other interf)72493 Q 2.75(aces. Thus)-.11 F(it is important for all the PIM routers in a domain to be able to map)2.75 E(each multicast group to the correct RP address.)72 506 Q(There are a number of w)72 532 Q(ays that group-to-RP mapping can be done; the simplest solution is for)-.11 E(all the routers in the domain to be con\214gured with the same i\nformation.)72 545 Q(Ho)5.5 E(we)-.275 E -.165(ve)-.275 G .88 -.44(r, s).165 H(tatic).44 E(con\214guration generally doesn')72 558 Q 2.75(ts)-.198 G(cale well, and also does not dynamically adapt to route around)-2.75 E(router or link f)72 571 Q 2.75(ailures. The)-.11 F(mechanism speci\214ed in this document is kno)2.75 E(wn as the PIM BootStrap)-.275 E(Router mechanism, or BSR for short, and pro)72 584 Q(vides a dynamic, adapti)-.165 E .33 -.165(ve m)-.275 H(echanism to distrib).165 E(ute)-.22 E(group-to-RP mapping information rapidly throughout a domain.)72 597 Q(\Before we discuss the BSR mechanism itself, we should understand the ru\les a PIM-SM router)72 623 Q(will apply to the mapping information.)72636 Q(Irrespecti)5.5 E .33 -.165(ve o)-.275 H 2.75(fh).165 G .55 -.275(ow i)-2.75 H 2.75(to).275 G(btains the mapping information, a)-2.75 E(PIM-SM router will ha)72 649 Q .33 -.165(ve a m)-.22 H(apping table containing multiple entries, each of which has the).165 E(follo)72 662 Q(wing form:)-.275 E 7.15<834d>72 678.6 S(ulticast group range, e)-7.15 E(xpressed as an address and pre\214x length.)-.165 E 7.15<8352>72 695.2S 2.75(PP)-7.15 G(riority)-2.75 E(.)-.715 E 7.15<8349>72 711.8 S 2.75(Pa)-7.15 G(ddress of RP)-2.75 E(.)-1.221 E(Fenner/Handle)72 769 Q(y/K)-.165 E 188.515(ermode/Thaler Section)-.275 F 2.75(1.1. [P)2.75 F(age 3])-.165 E EP%%Page: 4 4%%BeginPageSetupBP%%EndPageSetup/F0 11/Times-Roman@0 SF(INTERNET)72 49 Q 72.802(-DRAFT Expires:)-1.012 F(August 2003)2.75 E(February 2003)103.569 E(In general, these mapping entries may o)72 85 Q -.165(ve)-.165 G(rlap in arbitrary w).165 E(ays; a particular multicast group may)-.11 E(be co)72 98 Q -.165(ve)-.165 G(red by multiple mapping entries.).165 E(When this is the case, the router chooses only one of the)5.5 E(entrie\s by applying a deterministic algorithm \(speci\214ed in the PIM-SM pro\tocol speci\214cation\) so)72 111 Q(that all routers in the domain mak)72 124 Q 2.75(et)-.11 G(he same choice of entry and hence apply the same group-to-)-2.75 E(RP mapping.)72 137 Q(The BSR mechanism pro)72 153.6 Q(vides a w)-.165 E(ay in which viable group-to-RP mappings can be created and)-.11 E(distrib)72 166.6 Q(uted to all the PIM-SM routers in a domain.)-.22 E(It is adapti)5.5 E -.165(ve)-.275 G 2.75(,i).165 G 2.75(nt)-2.75 G(hat if an RP becomes)-2.75 E(unreachable, this will be detected and th\e mapping tables will be modi\214ed so that the unreachable)72 179.6 Q(RP is no longer used, and the ne)72 192.6 Q 2.75(wt)-.275 G(ables will be rapidly distrib)-2.75 E(uted throughout the domain.)-.22E(The general idea behind the BSR-mechanism is that some of the PIM rou\ters within a PIM)72 209.2 Q(domain are con\214gured to be potential RPs for the domain.)72 222.2 Q(These are kno)5.5 E(wn as candidate-RPs \(C-)-.275 E 2.75(RPs\). A)72235.2 R(subset of the C-RPs will e)2.75 E -.165(ve)-.275 G(ntually be used as the actual RPs for the domain.).165 E(In)5.5 E(addi\tion, some of the PIM routers in the domain are con\214gured as candida\te bootstrap routers \(C-)72 248.2 Q 2.75(BSRs\). One)72 261.2 R(of these C-BSRs will be elected to serv)2.75 E 2.75(ea)-.165 G 2.75(st)-2.75 G(he bootstrap router \(BSR\) for the)-2.75 E(domain, and all the\ PIM routers in the domain will learn the result of this election throu\gh)72 274.2 Q(Bootstrap messages.)72 287.2 Q(The C-RPs will them report their candidac)5.5 E 2.75(yt)-.165 G 2.75(ot)-2.75 G(he elected BSR, which will)-2.75 E(choose a subset of the C\-RPs to form the actual set of RPs to the used.)72 300.2 Q(This RP-Set will then be)5.5 E(distrib)72 313.2 Q(uted out to all the routers in the domain through Bootstrap messages.)-.22 E(The mechanism is complicated slightly by the presence of administrati)72 329.8 Q -.165(ve)-.275 G(ly-scoped multicast).165 E(re)72 342.8 Q(gions within the PIM-SM domain.)-.165 E(An admin-scope re)5.5 E(gion is a con)-.165 E .33 -.165(vex c)-.44 H(onnected set of PIM).165 E