One document matched: draft-ietf-idmr-igmp-v3-11.ps

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/F0 10/Times-Roman@0 SF(INTERNET)72 84 Q 230.5(-DRAFT Brad)-.92 F
(Cain, Cere)2.5 E .5 -.25(va N)-.25 H(etw).25 E(orks)-.1 E
(Obsoletes RFC2236)72 96 Q(Ste)231.01 E .3 -.15(ve D)-.25 H
(eering, Cisco Systems).15 E(Bill Fenner)361.09 108 Q 2.5(,A)-.4 G
(T&T Labs - Research)-3.61 E(Isidor K)377.28 120 Q(ouv)-.35 E
(elas, Cisco Systems)-.15 E(Ajit Th)396.62 132 Q(yag)-.05 E
(arajan, Ericsson)-.05 E(Expires No)72 144 Q -.15(ve)-.15 G(mber 2002)
.15 E(May 2002)293.71 E(Internet Group Management Protocol, V)191.35 180
Q(ersion 3)-1.11 E(<draft-ietf-idmr)222.61 192 Q(-igmp-v3-11.ps>)-.2 E
/F1 10/Times-Bold@0 SF(ST)72 228 Q -.95(AT)-.9 G(US OF THIS MEMO).95 E
F0(This document is an Internet-Draft and is in full conformance with a\
ll pro)72 243.6 Q(visions of Section 10 of)-.15 E(RFC2026.)72 255.6 Q
(Internet-Drafts are w)72 271.2 Q
(orking documents of the Internet Engineering T)-.1 E(ask F)-.8 E
(orce \(IETF\), its areas,)-.15 E(and its)5 E -.1(wo)72 283.2 S
(rking groups.).1 E(Note that other groups may also distrib)5 E(ute w)
-.2 E(orking documents as Internet- Drafts.)-.1 E
(Internet-Drafts are draft documents v)72 298.8 Q
(alid for a maximum of six months and may be updated, replaced, or)-.25
E(obsoleted by other documents at an)72 310.8 Q 2.5(yt)-.15 G 2.5
(ime. It)-2.5 F
(is inappropriate to use Internet-Drafts as reference material or)2.5 E
(to cite them other than as w)72 322.8 Q(ork in progress.)-.1 E 2.5
(The list of current Internet-Drafts can be accessed at)72 338.4 R
(http://www)2.5 E(.ietf.or)-.65 E(g/ietf/1id-abstracts.txt)-.18 E
(The list of Internet-Draft Shado)72 354 Q 5(wD)-.25 G
(irectories can be accessed at http://www)-5 E(.ietf.or)-.65 E(g/shado)
-.18 E -.65(w.)-.25 G(html.).65 E F1(Abstract)72 378 Q F0
(This document speci\214es V)72 393.6 Q
(ersion 3 of the Internet Group Management Protocol, IGMPv3.)-1.11 E
(IGMP is the)5 E(protocol used by IPv4 systems to report their IP multi\
cast group memberships to neighboring multicast)72 405.6 Q 2.5
(routers. V)72 417.6 R(ersion 3 of IGMP adds support for "source \214lt\
ering", that is, the ability for a system to report)-1.11 E
(interest in recei)72 429.6 Q(ving pack)-.25 E
(ets *only* from speci\214c source addresses, or from *all b)-.1 E
(ut* speci\214c source)-.2 E
(addresses, sent to a particular multicast address.)72 441.6 Q
(That information may be used by multicast routing)5 E(protocols to a)72
453.6 Q -.2(vo)-.2 G(id deli).2 E -.15(ve)-.25 G(ring multicast pack).15
E(ets from speci\214c sources to netw)-.1 E(orks where there are no)-.1
E(interested recei)72 465.6 Q -.15(ve)-.25 G(rs.).15 E
(This document obsoletes RFC 2236.)72 481.2 Q
(This document is a product of the Inter)72 496.8 Q
(-Domain Multicast Routing w)-.2 E(orking group within the Internet)-.1
E(Engineering T)72 508.8 Q(ask F)-.8 E 2.5(orce. Comments)-.15 F
(are solicited and should be addressed to the w)2.5 E(orking group')-.1
E 2.5(sm)-.55 G(ailing)-2.5 E
(list at idmr@cs.ucl.ac.uk and/or the authors.)72 520.8 Q
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 210.43(arajan [P)-.05 F(age 1])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 12/Times-Bold@0 SF -1.104(Ta)242.886 84 S
(ble of Contents)1.104 E F0(1. Introduction)72 120 Q -2.5 10
(............................ 3)7.56 H(2. The Service Interf)72 132 Q
(ace for Requesting IP Multicast Reception)-.1 E -2.5 10
(............. 3)2.15 H
(3. Multicast Reception State Maintained by Systems)72 144 Q -2.5 10
(................ 4)7.28 H(4. Message F)72 156 Q 9.38(ormats .)-.15 F
-2.5 10(......................... 6)10 H
(5. Description of the Protocol for Group Members)72 168 Q -7.5 10
(................. 1)3.42 H(4)-10 E
(6. Description of the Protocol for Multicast Routers)72 180 Q -7.5 10
(................ 1)10.35 H(8)-10 E(7. Interoperation with Older V)72
192 Q(ersions of IGMP)-1.11 E -7.5 10(.................. 2)4.53 H(5)-10
E(8. List of T)72 204 Q(imers, Counters, and their Def)-.35 E(ault V)-.1
E 4.7(alues .)-1.11 F -7.5 10(............... 2)10 H(8)-10 E
(9. Security Considerations)72 216 Q -7.5 10(........................ 3)
11.17 H(1)-10 E(10. IAN)72 228 Q 2.5(AC)-.35 G -.14(onsiderations .)-2.5
F -7.5 10(........................ 3)10 H(3)-10 E(11. Ackno)72 240 Q
-.24(wledgments .)-.25 F -7.5 10(......................... 3)10 H(3)-10
E(12. Normati)72 252 Q .3 -.15(ve R)-.25 H -2.29(eferences .).15 F -7.5
10(........................ 3)10 H(3)-10 E(13. Informati)72 264 Q .3
-.15(ve R)-.25 H 5.77(eferences .).15 F -7.5 10
(....................... 3)10 H(3)-10 E(Appendix A. Design Rationale)72
276 Q -7.5 10(....................... 3)6.18 H(5)-10 E
(Appendix B. Summary of changes from IGMPv2)72 288 Q -7.5 10
(................. 3)7.02 H(6)-10 E(Cain, Deering, Fenner)72 768 Q 2.5
(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 210.43(arajan [P)-.05 F
(age 2])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(1. INTR)72 84 R(ODUCTION)
-.3 E F0(The Internet Group Management Protocol \(IGMP\) is used by IPv\
4 systems \(hosts and routers\) to report)72 99.6 Q
(their IP multicast group memberships to an)72 111.6 Q 2.5(yn)-.15 G
(eighboring multicast routers.)-2.5 E(Note that an IP multicast router)5
E(may itself be a member of one or more multicast groups, in which case\
 it performs both the "multicast)72 123.6 Q(router part" of the protoco\
l \(to collect the membership information needed by its multicast routi\
ng protocol\))72 135.6 Q(and the "group member part" of the protocol \(\
to inform itself and other)72 147.6 Q 2.5(,n)-.4 G
(eighboring multicast routers of its)-2.5 E(memberships\).)72 159.6 Q(I\
GMP is also used for other IP multicast management functions, using mes\
sage types other than those used)72 175.2 Q
(for group membership reporting.)72 187.2 Q(This document speci\214es o\
nly the group membership reporting functions)5 E(and messages.)72 199.2
Q(This document speci\214es V)72 214.8 Q(ersion 3 of IGMP)-1.11 E 5(.V)
-1.11 G(ersion 1, speci\214ed in [RFC-1112], w)-6.11 E
(as the \214rst widely-)-.1 E(deplo)72 226.8 Q(yed v)-.1 E
(ersion and the \214rst v)-.15 E(ersion to become an Internet Standard.)
-.15 E -1.11(Ve)5 G(rsion 2, speci\214ed in [RFC-2236],)1.11 E
(added support for "lo)72 238.8 Q 2.5(wl)-.25 G(ea)-2.5 E .3 -.15(ve l)
-.2 H(atenc).15 E(y", that is, a reduction in the time it tak)-.15 E
(es for a multicast router to learn)-.1 E(that there are no longer an)72
250.8 Q 2.5(ym)-.15 G
(embers of a particular group present on an attached netw)-2.5 E 2.5
(ork. V)-.1 F(ersion 3 adds)-1.11 E(support for "source \214ltering", t\
hat is, the ability for a system to report interest in recei)72 262.8 Q
(ving pack)-.25 E(ets *only*)-.1 E(from speci\214c source addresses, as\
 required to support Source-Speci\214c Multicast [SSM], or from *all b)
72 274.8 Q(ut*)-.2 E
(speci\214c source addresses, sent to a particular multicast address.)72
286.8 Q -1.11(Ve)5 G(rsion 3 is designed to be interoperable)1.11 E
(with V)72 298.8 Q(ersions 1 and 2.)-1.11 E(Multicast Listener Disco)72
314.4 Q -.15(ve)-.15 G(ry \(MLD\) is used in a similar w).15 E
(ay by IPv6 systems.)-.1 E(MLD v)5 E(ersion 1 [MLD])-.15 E
(implements the functionality of IGMP v)72 326.4 Q(ersion 2; MLD v)-.15
E(ersion 2 [MLDv2] implements the functionality of)-.15 E(IGMP v)72
338.4 Q(ersion 3.)-.15 E(The capitalized k)72 354 Q .3 -.15(ey w)-.1 H
(ords "MUST", "MUST NO).05 E(T", "REQ)-.4 E(UIRED", "SHALL", "SHALL NO)
-.1 E(T",)-.4 E("SHOULD", "SHOULD NO)72 366 Q(T", "RECOMMENDED", "MA)-.4
E(Y", and "OPTION)-1.05 E(AL" in this document are to)-.35 E
(be interpreted as described in [RFC-2119].)72 378 Q
(Due to the lack of italics, emphasis is indicated herein by)5 E(brack)
72 390 Q(eting a w)-.1 E(ord or phrase in "*" characters.)-.1 E F1 2.5
(2. THE)72 426 R(SER)2.5 E(VICE INTERF)-.55 E -.55(AC)-.9 G 2.5(EF).55 G
(OR REQ)-2.5 E(UESTING IP MUL)-.1 E(TICAST RECEPTION)-.92 E F0 -.4(Wi)72
441.6 S
(thin an IP system, there is \(at least conceptually\) a service interf)
.4 E(ace used by upper)-.1 E(-layer protocols or)-.2 E(application prog\
rams to ask the IP layer to enable and disable reception of pack)72
453.6 Q(ets sent to speci\214c IP)-.1 E(multicast addresses.)72 465.6 Q
(In order to tak)5 E 2.5(ef)-.1 G(ull adv)-2.5 E
(antage of the capabilities of IGMPv3, a system')-.25 E 2.5(sI)-.55 G
2.5(Ps)-2.5 G(ervice)-2.5 E(interf)72 477.6 Q
(ace must support the follo)-.1 E(wing operation:)-.25 E
(IPMulticastListen \( sock)89.5 501.6 Q(et, interf)-.1 E
(ace, multicast-address,)-.1 E(\214lter)139.5 513.6 Q
(-mode, source-list \))-.2 E(where:)72 537.6 Q 5(o")72 553.2 S(sock)-5 E
(et" is an implementation-speci\214c parameter used to distinguish amon\
g dif)-.1 E(ferent requesting entities)-.25 E
(\(e.g., programs or processes\) within the system; the sock)82 565.2 Q
(et parameter of BSD Unix system calls is a)-.1 E(speci\214c e)82 577.2
Q(xample.)-.15 E 5(o")72 592.8 S(interf)-5 E
(ace" is a local identi\214er of the netw)-.1 E(ork interf)-.1 E
(ace on which reception of the speci\214ed multicast)-.1 E
(address is to be enabled or disabled.)82 604.8 Q(Interf)5 E
(aces may be ph)-.1 E(ysical \(e.g., an Ethernet interf)-.05 E
(ace\) or virtual)-.1 E(\(e.g., the endpoint of a Frame Relay virtual c\
ircuit or the endpoint of an IP-in-IP "tunnel"\).)82 616.8 Q(An)5 E
(implementation may allo)82 628.8 Q 2.5(was)-.25 G
(pecial "unspeci\214ed" v)-2.5 E(alue to be passed as the interf)-.25 E
(ace parameter)-.1 E 2.5(,i)-.4 G 2.5(nw)-2.5 G(hich)-2.5 E
(case the request w)82 640.8 Q(ould apply to the "primary" or "def)-.1 E
(ault" interf)-.1 E(ace of the system \(perhaps established by)-.1 E
(system con\214guration\).)82 652.8 Q(If reception of the same multicas\
t address is desired on more than one interf)5 E(ace,)-.1 E
(IPMulticastListen is in)82 664.8 Q -.2(vo)-.4 G -.1(ke).2 G 2.5(ds).1 G
(eparately for each desired interf)-2.5 E(ace.)-.1 E 5(o")72 680.4 S(mu\
lticast-address" is the IP multicast address, or group, to which the re\
quest pertains.)-5 E(If reception of)5 E
(more than one multicast address on a gi)82 692.4 Q -.15(ve)-.25 G 2.5
(ni).15 G(nterf)-2.5 E(ace is desired, IPMulticastListen is in)-.1 E -.2
(vo)-.4 G -.1(ke).2 G 2.5(ds).1 G(eparately)-2.5 E
(for each desired multicast address.)82 704.4 Q(Cain, Deering, Fenner)72
768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 210.43
(arajan [P)-.05 F(age 3])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E 5(o")72 84 S(\214lter)-5 E
(-mode" may be either INCLUDE or EXCLUDE.)-.2 E
(In INCLUDE mode, reception of pack)5 E(ets sent to)-.1 E(the speci\214\
ed multicast address is requested *only* from those IP source addresses\
 listed in the source-list)82 96 Q(parameter)82 108 Q 5(.I)-.55 G 2.5
(nE)-5 G(XCLUDE mode, reception of pack)-2.5 E(ets sent to the gi)-.1 E
-.15(ve)-.25 G 2.5(nm).15 G(ulticast address is requested)-2.5 E
(from all IP source addresses *e)82 120 Q
(xcept* those listed in the source-list parameter)-.15 E(.)-.55 E 5(o")
72 135.6 S(source-list" is an unordered list of zero or more IP unicast\
 addresses from which multicast reception is)-5 E
(desired or not desired, depending on the \214lter mode.)82 147.6 Q
(An implementation MA)5 E 2.5(Yi)-1.05 G(mpose a limit on the size)-2.5
E(of source lists, b)82 159.6 Q(ut that limit MUST NO)-.2 E 2.5(Tb)-.4 G
2.5(el)-2.5 G
(ess than 64 addresses per list. When an operation causes the)-2.5 E
(source list size limit to be e)82 171.6 Q(xceeded, the service interf)
-.15 E(ace MUST return an error)-.1 E(.)-.55 E -.15(Fo)72 187.2 S 2.5
(rag).15 G -2.15 -.25(iv e)-2.5 H 2.5(nc).25 G(ombination of sock)-2.5 E
(et, interf)-.1 E(ace, and multicast address, only a single \214lter mo\
de and source list)-.1 E(can be in ef)72 199.2 Q(fect at an)-.25 E 2.5
(yo)-.15 G(ne time.)-2.5 E(Ho)5 E(we)-.25 E -.15(ve)-.25 G .8 -.4(r, e)
.15 H
(ither the \214lter mode or the source list, or both, may be changed).4
E(by subsequent IPMulticastListen requests that specify the same sock)72
211.2 Q(et, interf)-.1 E(ace, and multicast address.)-.1 E
(Each subsequent request completely replaces an)72 223.2 Q 2.5(ye)-.15 G
(arlier request for the gi)-2.5 E -.15(ve)-.25 G 2.5(ns).15 G(ock)-2.5 E
(et, interf)-.1 E(ace and)-.1 E(multicast address.)72 235.2 Q(Pre)72
250.8 Q(vious v)-.25 E(ersions of IGMP did not support source \214lters\
 and had a simpler service interf)-.15 E(ace consisting of)-.1 E
(Join and Lea)72 262.8 Q .3 -.15(ve o)-.2 H
(perations to enable and disable reception of a gi).15 E -.15(ve)-.25 G
2.5(nm).15 G(ulticast address \(from *all* sources\))-2.5 E(on a gi)72
274.8 Q -.15(ve)-.25 G 2.5(ni).15 G(nterf)-2.5 E 2.5(ace. The)-.1 F
(equi)2.5 E -.25(va)-.25 G(lent operations in the ne).25 E 2.5(ws)-.25 G
(ervice interf)-2.5 E(ace follo)-.1 E(w:)-.25 E
(The Join operation is equi)72 290.4 Q -.25(va)-.25 G(lent to).25 E
(IPMulticastListen \( sock)97 314.4 Q(et, interf)-.1 E
(ace, multicast-address,)-.1 E(EXCLUDE, {} \))147 326.4 Q(and the Lea)72
350.4 Q .3 -.15(ve o)-.2 H(peration is equi).15 E -.25(va)-.25 G
(lent to:).25 E(IPMulticastListen \( sock)97 374.4 Q(et, interf)-.1 E
(ace, multicast-address,)-.1 E(INCLUDE, {} \))147 386.4 Q
(where {} is an empty source list.)72 410.4 Q(An e)72 426 Q
(xample of an API pro)-.15 E
(viding the capabilities outlined in this service interf)-.15 E
(ace is in [FIL)-.1 E(TER-API].)-.92 E/F1 10/Times-Bold@0 SF 2.5(3. MUL)
72 462 R(TICAST RECEPTION ST)-.92 E -.95(AT)-.9 G 2.5(EM).95 G(AINT)-2.5
E(AINED BY SYSTEMS)-.9 E 2.5(3.1. Sock)72 498 R(et State)-.1 E F0 -.15
(Fo)72 513.6 S 2.5(re).15 G(ach sock)-2.5 E
(et on which IPMulticastListen has been in)-.1 E -.2(vo)-.4 G -.1(ke).2
G(d, the system records the desired multicast).1 E
(reception state for that sock)72 525.6 Q 2.5(et. That)-.1 F
(state conceptually consists of a set of records of the form:)72 537.6 Q
(\(interf)92 561.6 Q(ace, multicast-address, \214lter)-.1 E
(-mode, source-list\))-.2 E(The sock)72 577.2 Q(et state e)-.1 E -.2(vo)
-.25 G(lv).2 E(es in response to each in)-.15 E -.2(vo)-.4 G
(cation of IPMulticastListen on the sock).2 E(et, as follo)-.1 E(ws:)
-.25 E 5(oI)72 592.8 S 2.5(ft)-5 G(he requested \214lter mode is INCLUD\
E *and* the requested source list is empty)-2.5 E 2.5(,t)-.65 G
(hen the entry)-2.5 E(corresponding to the requested)82 604.8 Q(interf)
82 616.8 Q(ace and multicast address is deleted if present.)-.1 E
(If no such entry is present, the request is ignored.)5 E 5(oI)72 632.4
S 2.5(ft)-5 G(he requested \214lter mode is EXCLUDE *or* the requested \
source list is non-empty)-2.5 E 2.5(,t)-.65 G(hen the entry)-2.5 E
(corresponding to the requested interf)82 644.4 Q
(ace and multicast address, if present, is changed to contain the)-.1 E
(requested \214lter mode and source list.)82 656.4 Q
(If no such entry is present, a ne)5 E 2.5(we)-.25 G
(ntry is created, using the)-2.5 E
(parameters speci\214ed in the request.)82 668.4 Q
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 210.43(arajan [P)-.05 F(age 4])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(3.2. Interface)72 84 R
(State)2.5 E F0(In addition to the per)72 99.6 Q(-sock)-.2 E(et multica\
st reception state, a system must also maintain or compute multicast)-.1
E(reception state for each of its interf)72 111.6 Q 2.5(aces. That)-.1 F
(state conceptually consists of a set of records of the form:)2.5 E
(\(multicast-address, \214lter)97 135.6 Q(-mode, source-list\))-.2 E
(At most one record per multicast-address e)72 151.2 Q(xists for a gi)
-.15 E -.15(ve)-.25 G 2.5(ni).15 G(nterf)-2.5 E 2.5(ace. This)-.1 F(per)
2.5 E(-interf)-.2 E(ace state is deri)-.1 E -.15(ve)-.25 G(d).15 E
(from the per)72 163.2 Q(-sock)-.2 E(et state, b)-.1 E(ut may dif)-.2 E
(fer from the per)-.25 E(-sock)-.2 E(et state when dif)-.1 E
(ferent sock)-.25 E(ets ha)-.1 E .3 -.15(ve d)-.2 H(if).15 E(fering)-.25
E(\214lter modes and/or source lists for the same multicast address and\
 interf)72 175.2 Q 2.5(ace. F)-.1 F(or e)-.15 E(xample, suppose one)-.15
E(application or process in)72 187.2 Q -.2(vo)-.4 G -.1(ke).2 G 2.5(st)
.1 G(he follo)-2.5 E(wing operation on sock)-.25 E(et s1:)-.1 E
(IPMulticastListen \( s1, i, m, INCLUDE, {a, b, c} \))97 211.2 Q
(requesting reception on interf)72 235.2 Q(ace i of pack)-.1 E
(ets sent to multicast address m, *only* if the)-.1 E 2.5(yc)-.15 G
(ome from source)-2.5 E(a, b, or c.)72 247.2 Q
(Suppose another application or process in)5 E -.2(vo)-.4 G -.1(ke).2 G
2.5(st).1 G(he follo)-2.5 E(wing operation on sock)-.25 E(et s2:)-.1 E
(IPMulticastListen \( s2, i, m, INCLUDE, {b, c, d} \))97 271.2 Q
(requesting reception on the same interf)72 295.2 Q(ace i of pack)-.1 E
(ets sent to the same multicast address m, *only* if the)-.1 E(y)-.15 E
(come from sources b, c, or d.)72 307.2 Q
(In order to satisfy the reception requirements of both sock)5 E
(ets, it is necessary)-.1 E(for interf)72 319.2 Q(ace i to recei)-.1 E
.3 -.15(ve p)-.25 H(ack).15 E(ets sent to m from an)-.1 E 2.5(yo)-.15 G
(ne of the sources a, b, c, or d.)-2.5 E(Thus, in this e)5 E(xample,)
-.15 E(the reception state of interf)72 331.2 Q(ace i for multicast add\
ress m has \214lter mode INCLUDE and source list {a, b, c,)-.1 E(d}.)72
343.2 Q(After a multicast pack)72 358.8 Q
(et has been accepted from an interf)-.1 E(ace by the IP layer)-.1 E 2.5
(,i)-.4 G(ts subsequent deli)-2.5 E -.15(ve)-.25 G(ry to the).15 E
(application or process listening on a particular sock)72 370.8 Q
(et depends on the multicast reception state of that sock)-.1 E(et)-.1 E
([and possibly also on other conditions, such as what transport- layer \
port the sock)72 382.8 Q(et is bound to].)-.1 E(So, in the)5 E(abo)72
394.8 Q .3 -.15(ve ex)-.15 H(ample, if a pack).15 E(et arri)-.1 E -.15
(ve)-.25 G 2.5(so).15 G 2.5(ni)-2.5 G(nterf)-2.5 E
(ace i, destined to multicast address m, with source address a, it)-.1 E
(will be deli)72 406.8 Q -.15(ve)-.25 G(red on sock).15 E(et s1 b)-.1 E
(ut not on sock)-.2 E
(et s2. Note that IGMP Queries and Reports are not subject to)-.1 E
(source \214ltering and must al)72 418.8 Q -.1(wa)-.1 G
(ys be processed by hosts and routers.).1 E(Filtering of pack)72 434.4 Q
(ets based upon a sock)-.1 E(et')-.1 E 2.5(sm)-.55 G
(ulticast reception state state is a ne)-2.5 E 2.5(wf)-.25 G
(eature of this service)-2.5 E(interf)72 446.4 Q 2.5(ace. The)-.1 F(pre)
2.5 E(vious service interf)-.25 E(ace [RFC1112] described no \214lterin\
g based upon multicast join state;)-.1 E(rather)72 458.4 Q 2.5(,aj)-.4 G
(oin on a sock)-2.5 E
(et simply caused the host to join a group on the gi)-.1 E -.15(ve)-.25
G 2.5(ni).15 G(nterf)-2.5 E(ace, and pack)-.1 E(ets destined)-.1 E
(for that group could be deli)72 470.4 Q -.15(ve)-.25 G(red to all sock)
.15 E(ets whether the)-.1 E 2.5(yh)-.15 G(ad joined or not.)-2.5 E
(The general rules for deri)72 486 Q(ving the per)-.25 E(-interf)-.2 E
(ace state from the per)-.1 E 2.5(-s)-.2 G(ock)-2.5 E
(et state are as follo)-.1 E 2.5(ws: F)-.25 F(or each)-.15 E
(distinct \(interf)72 498 Q
(ace, multicast- address\) pair that appears in an)-.1 E 2.5(ys)-.15 G
(ock)-2.5 E(et state, a per)-.1 E(-interf)-.2 E(ace record is created)
-.1 E(for that multicast address on that interf)72 510 Q 2.5
(ace. Considering)-.1 F(all sock)2.5 E
(et records containing the same \(interf)-.1 E(ace,)-.1 E
(multicast-address\) pair)72 522 Q(,)-.4 E(Cain, Deering, Fenner)72 768
Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 210.43(arajan [P)
-.05 F(age 5])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E 5(oi)72 84 S 2.5(f*)-5 G(an)-2.5 E(y* such record ha\
s a \214lter mode of EXCLUDE, then the \214lter mode of the interf)-.15
E(ace record is)-.1 E(EXCLUDE, and the source list of the interf)82 96 Q
(ace record is the intersection of the source lists of all sock)-.1 E
(et)-.1 E(records in EXCLUDE mode, minus those source addresses that ap\
pear in an)82 108 Q 2.5(ys)-.15 G(ock)-2.5 E(et record in)-.1 E
(INCLUDE mode.)82 120 Q -.15(Fo)5 G 2.5(re).15 G(xample, if the sock)
-2.65 E(et records for multicast address m on interf)-.1 E(ace i are:)
-.1 E(from sock)107 144 Q(et s1:)-.1 E 2.5(\(i)5 G 2.5(,m)-2.5 G 2.5(,E)
-2.5 G(XCLUDE, {a, b, c, d} \))-2.5 E(from sock)107 156 Q(et s2:)-.1 E
2.5(\(i)5 G 2.5(,m)-2.5 G 2.5(,E)-2.5 G(XCLUDE, {b, c, d, e} \))-2.5 E
(from sock)107 168 Q(et s3:)-.1 E 2.5(\(i)5 G 2.5(,m)-2.5 G 2.5(,I)-2.5
G(NCLUDE, {d, e, f} \))-2.5 E(then the corresponding interf)82 192 Q
(ace record on interf)-.1 E(ace i is:)-.1 E 2.5(\(m)149.5 216 S 2.5(,E)
-2.5 G(XCLUDE, {b, c} \))-2.5 E(If a fourth sock)82 240 Q
(et is added, such as:)-.1 E(from sock)107 264 Q(et s4:)-.1 E 2.5(\(i)5
G 2.5(,m)-2.5 G 2.5(,E)-2.5 G(XCLUDE, {} \))-2.5 E(then the interf)82
288 Q(ace record becomes:)-.1 E 2.5(\(m)149.5 312 S 2.5(,E)-2.5 G
(XCLUDE, {} \))-2.5 E 5(oi)72 327.6 S 2.5(f*)-5 G(all* such records ha)
-2.5 E .3 -.15(ve a \214)-.2 H
(lter mode of INCLUDE, then the \214lter mode of the interf).15 E
(ace record is)-.1 E(INCLUDE, and the source list of the interf)82 339.6
Q(ace record is the union of the source lists of all the sock)-.1 E(et)
-.1 E 2.5(records. F)82 351.6 R(or e)-.15 E(xample, if the sock)-.15 E
(et records for multicast address m on interf)-.1 E(ace i are:)-.1 E
(from sock)107 375.6 Q(et s1:)-.1 E 2.5(\(i)5 G 2.5(,m)-2.5 G 2.5(,I)
-2.5 G(NCLUDE, {a, b, c} \))-2.5 E(from sock)107 387.6 Q(et s2:)-.1 E
2.5(\(i)5 G 2.5(,m)-2.5 G 2.5(,I)-2.5 G(NCLUDE, {b, c, d} \))-2.5 E
(from sock)107 399.6 Q(et s3:)-.1 E 2.5(\(i)5 G 2.5(,m)-2.5 G 2.5(,I)
-2.5 G(NCLUDE, {e, f} \))-2.5 E(then the corresponding interf)82 423.6 Q
(ace record on interf)-.1 E(ace i is:)-.1 E 2.5(\(m)149.5 447.6 S 2.5
(,I)-2.5 G(NCLUDE, {a, b, c, d, e, f} \))-2.5 E
(An implementation MUST NO)82 471.6 Q 2.5(Tu)-.4 G(se an EXCLUDE interf)
-2.5 E(ace record to represent a group when all)-.1 E(sock)82 483.6 Q(e\
ts for this group are in INCLUDE state. If system resource limits are r\
eached when an interf)-.1 E(ace)-.1 E(state source list is calculated, \
an error MUST be returned to the application which requested the)82
495.6 Q(operation.)82 507.6 Q(The abo)72 523.2 Q .3 -.15(ve r)-.15 H
(ules for deri).15 E(ving the interf)-.25 E(ace state are \(re-\)e)-.1 E
-.25(va)-.25 G(luated whene).25 E -.15(ve)-.25 G 2.5(ra).15 G 2.5(nI)
-2.5 G(PMulticastListen in)-2.5 E -.2(vo)-.4 G(cation).2 E
(modi\214es the sock)72 535.2 Q
(et state by adding, deleting, or modifying a per)-.1 E(-sock)-.2 E
(et state record.)-.1 E(Note that a change)5 E(of)5 E(sock)72 547.2 Q
(et state does not necessarily result in a change of interf)-.1 E
(ace state.)-.1 E/F1 10/Times-Bold@0 SF 2.5(4. MESSA)72 583.2 R
(GE FORMA)-.55 E(TS)-.95 E F0(IGMP messages are encapsulated in IPv4 da\
tagrams, with an IP protocol number of 2.)72 598.8 Q(Ev)5 E(ery IGMP)
-.15 E(message described in this document is sent with an IP T)72 610.8
Q(ime-to-Li)-.35 E .3 -.15(ve o)-.25 H 2.5(f1).15 G 2.5(,I)-2.5 G 2.5
(PP)-2.5 G(recedence of Internetw)-2.5 E(ork)-.1 E(Control \(e.g.)72
622.8 Q -.8(Ty)5 G(pe of Service 0xc0\), and carries an IP Router Alert\
 option [RFC-2113] in its IP header).8 E(.)-.55 E
(IGMP message types are re)72 634.8 Q(gistered by the IAN)-.15 E 2.5(A[)
-.35 G(IAN)-2.5 E(A-REG] as described by [RFC-3228].)-.35 E
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 210.43(arajan [P)-.05 F(age 6])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(There are tw)72 84 Q 2.5(oI)-.1 G(GMP message types \
of concern to the IGMPv3 protocol described in this document:)-2.5 E/F1
10/Courier@0 SF(Type Number \(hex\))96 108 Q(Message Name)18 E 12
(----------------- ------------)96 120 R 54(0x11 Membership)132 144 R
(Query)6 E 54(0x22 Version)132 168 R 6(3M)6 G(embership Report)-6 E F0
(An implementation of IGMPv3 MUST also support the follo)72 183.6 Q
(wing three message types, for interoperation)-.25 E(with pre)72 195.6 Q
(vious v)-.25 E(ersions of IGMP \(see section 7\):)-.15 E F1 54
(0x12 Version)132 219.6 R 6(1M)6 G(embership Report)-6 E([RFC-1112])24 E
54(0x16 Version)132 243.6 R 6(2M)6 G(embership Report)-6 E([RFC-2236])24
E 54(0x17 Version)132 267.6 R 6(2L)6 G(eave Group)-6 E([RFC-2236])60 E
F0(Unrecognized message types MUST be silently ignored.)72 283.2 Q
(Other message types may be used by ne)5 E(wer)-.25 E -.15(ve)72 295.2 S
(rsions or e).15 E(xtensions of IGMP)-.15 E 2.5(,b)-1.11 G 2.5(ym)-2.5 G
(ulticast routing protocols, or for other uses.)-2.5 E
(In this document, unless otherwise quali\214ed, the capitalized w)72
310.8 Q(ords "Query" and "Report" refer to IGMP)-.1 E
(Membership Queries and IGMP V)72 322.8 Q
(ersion 3 Membership Reports, respecti)-1.11 E -.15(ve)-.25 G(ly).15 E
(.)-.65 E/F2 10/Times-Bold@0 SF 2.5(4.1. Membership)72 358.8 R
(Query Message)2.5 E F0(Membership Queries are sent by IP multicast rou\
ters to query the multicast reception state of neighboring)72 374.4 Q
(interf)72 386.4 Q 2.5(aces. Queries)-.1 F(ha)2.5 E .3 -.15(ve t)-.2 H
(he follo).15 E(wing format:)-.25 E F1 114(0123)96 410.4 S 6
(01234567890123456789012345678901)96 422.4 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
434.4 Q 12(|T)90 446.4 S(ype = 0x11)-12 E 6(|M)12 G(ax Resp Code |)-6 E
66(Checksum |)66 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
458.4 Q 150(|G)90 470.4 S(roup Address)-150 E(|)150 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
482.4 Q 6(|R)90 494.4 S 6(esv |S|)-6 F(QRV |)6 E 30(QQIC |)30 F
(Number of Sources \(N\))30 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
506.4 Q 138(|S)90 518.4 S(ource Address [1])-138 E(|)132 E 360(+- -+)90
530.4 R 138(|S)90 542.4 S(ource Address [2])-138 E(|)132 E 174(+- . -+)
90 554.4 R 186(...)90 566.4 S 186(...)90 578.4 S 360(+- -+)90 590.4 R
138(|S)90 602.4 S(ource Address [N])-138 E(|)132 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
614.4 Q F0(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E
(elas, Th)-.15 E(yag)-.05 E 210.43(arajan [P)-.05 F(age 7])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(4.1.1. Max)72 84 R
(Resp Code)2.5 E F0
(The Max Resp Code \214eld speci\214es the maximum time allo)72 99.6 Q
(wed before sending a responding report.)-.25 E(The)5 E
(actual time allo)72 111.6 Q(wed, called the Max Resp T)-.25 E
(ime, is represented in units of 1/10 second and is deri)-.35 E -.15(ve)
-.25 G 2.5(df).15 G(rom)-2.5 E(the Max Resp Code as follo)72 123.6 Q
(ws:)-.25 E(If Max Resp Code < 128, Max Resp T)72 139.2 Q
(ime = Max Resp Code)-.35 E
(If Max Resp Code >= 128, Max Resp Code represents a \215oating-point v)
72 154.8 Q(alue as follo)-.25 E(ws:)-.25 E/F2 10/Courier@0 SF 6
(01234567)96 178.8 S(+-+-+-+-+-+-+-+-+)90 190.8 Q(|1| exp | mant)90
202.8 Q(|)12 E(+-+-+-+-+-+-+-+-+)90 214.8 Q F0(Max Resp T)72 230.4 Q
(ime = \(mant | 0x10\) << \(e)-.35 E(xp + 3\))-.15 E(Small v)72 246 Q
(alues of Max Resp T)-.25 E(ime allo)-.35 E 2.5(wI)-.25 G
(GMPv3 routers to tune the "lea)-2.5 E .3 -.15(ve l)-.2 H(atenc).15 E
(y" \(the time between the)-.15 E(moment the last host lea)72 258 Q -.15
(ve)-.2 G 2.5(sag).15 G(roup and the moment the routing protocol is not\
i\214ed that there are no more)-2.5 E 2.5(members\). Lar)72 270 R(ger v)
-.18 E(alues, especially in the e)-.25 E(xponential range, allo)-.15 E
2.5(wt)-.25 G(uning of the b)-2.5 E(urstiness of IGMP)-.2 E(traf)72 282
Q(\214c on a netw)-.25 E(ork.)-.1 E F1 2.5(4.1.2. Checksum)72 306 R F0
(The Checksum is the 16-bit one')72 321.6 Q 2.5(sc)-.55 G
(omplement of the one')-2.5 E 2.5(sc)-.55 G
(omplement sum of the whole IGMP message)-2.5 E
(\(the entire IP payload\).)72 333.6 Q -.15(Fo)5 G 2.5(rc).15 G
(omputing the checksum, the Checksum \214eld is set to zero.)-2.5 E
(When recei)5 E(ving)-.25 E(pack)72 345.6 Q(ets, the checksum MUST be v)
-.1 E(eri\214ed before processing a pack)-.15 E 2.5(et. [RFC-1071])-.1 F
F1 2.5(4.1.3. Gr)72 369.6 R(oup Addr)-.18 E(ess)-.18 E F0
(The Group Address \214eld is set to zero when sending a General Query)
72 385.2 Q 2.5(,a)-.65 G(nd set to the IP multicast address)-2.5 E(bein\
g queried when sending a Group-Speci\214c Query or Group-and-Source-Spe\
ci\214c Query \(see section)72 397.2 Q(4.1.9, belo)72 409.2 Q(w\).)-.25
E F1 2.5(4.1.4. Resv)72 433.2 R(\(Reser)2.5 E -.1(ve)-.1 G(d\)).1 E F0(\
The Resv \214eld is set to zero on transmission, and ignored on recepti\
on.)72 448.8 Q F1 2.5(4.1.5. S)72 472.8 R(Flag \(Suppr)2.5 E(ess Router)
-.18 E(-Side Pr)-.37 E(ocessing\))-.18 E F0
(When set to one, the S Flag indicates to an)72 488.4 Q 2.5(yr)-.15 G
(ecei)-2.5 E(ving multicast routers that the)-.25 E 2.5(ya)-.15 G
(re to suppress the normal)-2.5 E(timer updates the)72 500.4 Q 2.5(yp)
-.15 G(erform upon hearing a Query)-2.5 E 5(.I)-.65 G 2.5(td)-5 G
(oes not, ho)-2.5 E(we)-.25 E -.15(ve)-.25 G .8 -.4(r, s).15 H
(uppress the querier election or the).4 E(normal "host-side" processing\
 of a Query that a router may be required to perform as a consequence o\
f)72 512.4 Q(itself being a group member)72 524.4 Q(.)-.55 E F1 2.5
(4.1.6. QR)72 548.4 R 2.5(V\()-.55 G(Querier')-2.5 E 2.5(sR)-.37 G(ob)
-2.5 E(ustness V)-.2 E(ariable\))-.92 E F0(If non-zero, the QR)72 564 Q
2.5<568c>-.8 G(eld contains the [Rob)-2.5 E(ustness V)-.2 E(ariable] v)
-1.11 E(alue used by the querier)-.25 E 2.5(,i)-.4 G(.e., the sender of)
-2.5 E(the Query)72 576 Q 5(.I)-.65 G 2.5(ft)-5 G(he querier')-2.5 E 2.5
(s[)-.55 G(Rob)-2.5 E(ustness V)-.2 E(ariable] e)-1.11 E
(xceeds 7, the maximum v)-.15 E(alue of the QR)-.25 E 2.5<568c>-.8 G
(eld, the QR)-2.5 E(V)-.8 E(is set to zero.)72 588 Q
(Routers adopt the QR)5 E 2.5(Vv)-.8 G
(alue from the most recently recei)-2.75 E -.15(ve)-.25 G 2.5(dQ).15 G
(uery as their o)-2.5 E(wn)-.25 E([Rob)72 600 Q(ustness V)-.2 E
(ariable] v)-1.11 E(alue, unless that most recently recei)-.25 E -.15
(ve)-.25 G 2.5(dQ).15 G 1.6 -.8(RV w)-2.5 H
(as zero, in which case the recei).7 E -.15(ve)-.25 G(rs).15 E
(use the def)72 612 Q(ault [Rob)-.1 E(ustness V)-.2 E(ariable] v)-1.11 E
(alue speci\214ed in section 8.1 or a statically con\214gured v)-.25 E
(alue.)-.25 E(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E
(elas, Th)-.15 E(yag)-.05 E 210.43(arajan [P)-.05 F(age 8])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(4.1.7. QQIC)72 84 R
(\(Querier')2.5 E 2.5(sQ)-.37 G(uery Inter)-2.5 E -.1(va)-.1 G 2.5(lC).1
G(ode\))-2.5 E F0(The Querier')72 99.6 Q 2.5(sQ)-.55 G(uery Interv)-2.5
E(al Code \214eld speci\214es the [Query Interv)-.25 E
(al] used by the querier)-.25 E 2.5(.T)-.55 G(he actual)-2.5 E(interv)72
111.6 Q(al, called the Querier')-.25 E 2.5(sQ)-.55 G(uery Interv)-2.5 E
(al \(QQI\), is represented in units of seconds and is deri)-.25 E -.15
(ve)-.25 G 2.5(df).15 G(rom)-2.5 E(the Querier')72 123.6 Q 2.5(sQ)-.55 G
(uery Interv)-2.5 E(al Code as follo)-.25 E(ws:)-.25 E
(If QQIC < 128, QQI = QQIC)72 139.2 Q
(If QQIC >= 128, QQIC represents a \215oating-point v)72 154.8 Q
(alue as follo)-.25 E(ws:)-.25 E/F2 10/Courier@0 SF 6(01234567)96 178.8
S(+-+-+-+-+-+-+-+-+)90 190.8 Q(|1| exp | mant)90 202.8 Q(|)12 E
(+-+-+-+-+-+-+-+-+)90 214.8 Q F0(QQI = \(mant | 0x10\) << \(e)72 230.4 Q
(xp + 3\))-.15 E
(Multicast routers that are not the current querier adopt the QQI v)72
246 Q(alue from the most recently recei)-.25 E -.15(ve)-.25 G(d).15 E
(Query as their o)72 258 Q(wn [Query Interv)-.25 E(al] v)-.25 E
(alue, unless that most recently recei)-.25 E -.15(ve)-.25 G 2.5(dQ).15
G(QI w)-2.5 E(as zero, in which case)-.1 E(the recei)72 270 Q
(ving routers use the def)-.25 E(ault [Query Interv)-.1 E(al] v)-.25 E
(alue speci\214ed in section 8.2.)-.25 E F1 2.5(4.1.8. Number)72 294 R
(of Sour)2.5 E(ces \(N\))-.18 E F0
(The Number of Sources \(N\) \214eld speci\214es ho)72 309.6 Q 2.5(wm)
-.25 G(an)-2.5 E 2.5(ys)-.15 G(ource addresses are present in the Query)
-2.5 E 5(.T)-.65 G(his)-5 E
(number is zero in a General Query or a Group-Speci\214c Query)72 321.6
Q 2.5(,a)-.65 G(nd non-zero in a Group-and-Source-)-2.5 E
(Speci\214c Query)72 333.6 Q 5(.T)-.65 G
(his number is limited by the MTU of the netw)-5 E(ork o)-.1 E -.15(ve)
-.15 G 2.5(rw).15 G(hich the Query is transmitted.)-2.5 E -.15(Fo)72
345.6 S 2.5(re).15 G(xample, on an Ethernet with an MTU of 1500 octets,\
 the IP header including the Router Alert option)-2.65 E(consumes 24 oc\
tets, and the IGMP \214elds up to including the Number of Sources \(N\)\
 \214eld consume 12)72 357.6 Q(octets, lea)72 369.6 Q(ving 1464 octets \
for source addresses, which limits the number of source addresses to 36\
6)-.2 E(\(1464/4\).)72 381.6 Q F1 2.5(4.1.9. Sour)72 405.6 R(ce Addr)
-.18 E(ess [i])-.18 E F0(The Source Address [i] \214elds are a v)72
421.2 Q(ector of n IP unicast addresses, where n is the v)-.15 E
(alue in the Number of)-.25 E(Sources \(N\) \214eld.)72 433.2 Q F1 2.5
(4.1.10. Additional)72 457.2 R(Data)2.5 E F0(If the P)72 472.8 Q(ack)
-.15 E(et Length \214eld in the IP header of a recei)-.1 E -.15(ve)-.25
G 2.5(dQ).15 G(uery indicates that there are additional octets of)-2.5 E
(data present, be)72 484.8 Q(yond the \214elds described here, IGMPv3 i\
mplementations MUST include those octets in the)-.15 E(computation to v)
72 496.8 Q(erify the recei)-.15 E -.15(ve)-.25 G 2.5(dI).15 G
(GMP Checksum, b)-2.5 E
(ut MUST otherwise ignore those additional octets.)-.2 E
(When sending a Query)72 508.8 Q 2.5(,a)-.65 G 2.5(nI)-2.5 G
(GMPv3 implementation MUST NO)-2.5 E 2.5(Ti)-.4 G
(nclude additional octets be)-2.5 E(yond the)-.15 E
(\214elds described here.)72 520.8 Q F1 2.5(4.1.11. Query)72 544.8 R
-.92(Va)2.5 G(riants).92 E F0(There are three v)72 560.4 Q
(ariants of the Query message:)-.25 E 5(1. A)72 576 R("General Query" i\
s sent by a multicast router to learn the complete multicast reception \
state of the)2.5 E(neighboring interf)87 588 Q(aces)-.1 E
(\(that is, the interf)87 600 Q(aces attached to the netw)-.1 E
(ork on which the Query is transmitted\).)-.1 E(In a General Query)5 E
(,)-.65 E(both the Group Address \214eld and the Number of Sources \(N\
\) \214eld are zero.)87 612 Q 5(2. A)72 627.6 R("Group-Speci\214c Query\
" is sent by a multicast router to learn the reception state, with resp\
ect to a)2.5 E(*single* multicast address, of the neighboring interf)87
639.6 Q 2.5(aces. In)-.1 F 2.5(aG)2.5 G(roup-Speci\214c Query)-2.5 E 2.5
(,t)-.65 G(he Group)-2.5 E(Address \214eld contains the multicast addre\
ss of interest, and the Number of Sources \(N\) \214eld contains)87
651.6 Q(zero.)87 663.6 Q 5(3. A)72 679.2 R("Group-and-Source-Speci\214c\
 Query" is sent by a multicast router to learn if an)2.5 E 2.5(yn)-.15 G
(eighboring interf)-2.5 E(ace)-.1 E(desires reception of pack)87 691.2 Q
(ets sent to a speci\214ed multicast address, from an)-.1 E 2.5(yo)-.15
G 2.5(fas)-2.5 G(peci\214ed list of sources.)-2.5 E
(In a Group-and-Source-Speci\214c Query)87 703.2 Q 2.5(,t)-.65 G
(he Group Address \214eld contains the multicast address of)-2.5 E(inte\
rest, and the Source Address [i] \214elds contain the source address\(e\
s\) of interest.)87 715.2 Q(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G
(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 210.43(arajan [P)-.05 F(age 9])
-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(4.1.12. IP)72 84 R
(Destination Addr)2.5 E(esses f)-.18 E(or Queries)-.25 E F0(In IGMPv3, \
General Queries are sent with an IP destination address of 224.0.0.1, t\
he all-systems multicast)72 99.6 Q 2.5(address. Group-Speci\214c)72
111.6 R(and Group-and-Source-Speci\214c Queries are sent with an IP des\
tination address)2.5 E(equal to the)72 123.6 Q
(multicast address of interest.)5 E(*Ho)5 E(we)-.25 E -.15(ve)-.25 G
(r*, a system MUST accept and).15 E(process an)5 E 2.5(yQ)-.15 G(uery)
-2.5 E(whose IP Destination Address \214eld contains *an)72 135.6 Q
(y* of the addresses \(unicast or multicast\) assigned to the)-.15 E
(interf)72 147.6 Q(ace on which the Query arri)-.1 E -.15(ve)-.25 G(s.)
.15 E F1 2.5(4.2. V)72 183.6 R(ersion 3 Membership Report Message)-1 E
F0 -1.11(Ve)72 199.2 S(rsion 3 Membership Reports are sent by IP system\
s to report \(to neighboring routers\) the current)1.11 E(multicast rec\
eption state, or changes in the multicast reception state, of their int\
erf)72 211.2 Q 2.5(aces. Reports)-.1 F(ha)2.5 E .3 -.15(ve t)-.2 H(he)
.15 E(follo)72 223.2 Q(wing format:)-.25 E/F2 10/Courier@0 SF 114(0123)
96 247.2 S 6(01234567890123456789012345678901)96 259.2 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
271.2 Q 12(|T)90 283.2 S(ype = 0x22)-12 E 24(|R)12 G 12(eserved |)-24 F
66(Checksum |)66 F
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
295.2 Q 66(|R)90 307.2 S 66(eserved |)-66 F
(Number of Group Records \(M\))12 E(|)12 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
319.2 Q 378(||)90 331.2 S 378(..)90 343.2 S 144(.G)90 355.2 S
(roup Record [1])-144 E(.)138 E 378(..)90 367.2 S 378(||)90 379.2 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
391.2 Q 378(||)90 403.2 S 378(..)90 415.2 S 144(.G)90 427.2 S
(roup Record [2])-144 E(.)138 E 378(..)90 439.2 S 378(||)90 451.2 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
463.2 Q 186(|.|)90 475.2 S 186(...)90 487.2 S 186(|.|)90 499.2 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
511.2 Q 378(||)90 523.2 S 378(..)90 535.2 S 144(.G)90 547.2 S
(roup Record [M])-144 E(.)138 E 378(..)90 559.2 S 378(||)90 571.2 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
583.2 Q F0(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E
(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 10])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(where each Group Record has the follo)72 84 Q
(wing internal format:)-.25 E/F1 10/Courier@0 SF
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
108 Q 12(|R)90 120 S(ecord Type)-12 E 12(|A)12 G(ux Data Len |)-12 E
(Number of Sources \(N\))30 E(|)30 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
132 Q 138(|M)90 144 S(ulticast Address)-138 E(|)138 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
156 Q 138(|S)90 168 S(ource Address [1])-138 E(|)132 E 360(+- -+)90 180
R 138(|S)90 192 S(ource Address [2])-138 E(|)132 E 360(+- -+)90 204 R
186(...)90 216 S 186(...)90 228 S 186(...)90 240 S 360(+- -+)90 252 R
138(|S)90 264 S(ource Address [N])-138 E(|)132 E
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
276 Q 378(||)90 288 S 378(..)90 300 S 150(.A)90 312 S(uxiliary Data)-150
E(.)144 E 378(..)90 324 S 378(||)90 336 S
(+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+)90
348 Q/F2 10/Times-Bold@0 SF 2.5(4.2.1. Reser)72 372 R -.1(ve)-.1 G(d).1
E F0(The Reserv)72 387.6 Q
(ed \214elds are set to zero on transmission, and ignored on reception.)
-.15 E F2 2.5(4.2.2. Checksum)72 411.6 R F0
(The Checksum is the 16-bit one')72 427.2 Q 2.5(sc)-.55 G
(omplement of the one')-2.5 E 2.5(sc)-.55 G
(omplement sum of the whole IGMP message)-2.5 E
(\(the entire IP payload\).)72 439.2 Q -.15(Fo)5 G 2.5(rc).15 G
(omputing the checksum, the Checksum \214eld is set to zero.)-2.5 E
(When recei)5 E(ving)-.25 E(pack)72 451.2 Q(ets, the checksum MUST be v)
-.1 E(eri\214ed before processing a message.)-.15 E F2 2.5
(4.2.3. Number)72 475.2 R(of Gr)2.5 E(oup Records \(M\))-.18 E F0
(The Number of Group Records \(M\) \214eld speci\214es ho)72 490.8 Q 2.5
(wm)-.25 G(an)-2.5 E 2.5(yG)-.15 G
(roup Records are present in this Report.)-2.5 E F2 2.5(4.2.4. Gr)72
514.8 R(oup Record)-.18 E F0(Each Group Record is a block of \214elds c\
ontaining information pertaining to the sender')72 530.4 Q 2.5(sm)-.55 G
(embership in a)-2.5 E(single multicast group on the interf)72 542.4 Q
(ace from which the Report is sent.)-.1 E F2 2.5(4.2.5. Record)72 566.4
R -.74(Ty)2.5 G(pe).74 E F0(See section 4.2.12, belo)72 582 Q -.65(w.)
-.25 G F2 2.5(4.2.6. A)72 606 R(ux Data Len)-.5 E F0(The Aux Data Len \
\214eld contains the length of the Auxiliary Data \214eld in this Group\
 Record, in units of)72 621.6 Q(32-bit w)72 633.6 Q 2.5(ords. It)-.1 F
(may contain zero, to indicate the absence of an)2.5 E 2.5(ya)-.15 G
(uxiliary data.)-2.5 E F2 2.5(4.2.7. Number)72 657.6 R(of Sour)2.5 E
(ces \(N\))-.18 E F0(The Number of Sources \(N\) \214eld speci\214es ho)
72 673.2 Q 2.5(wm)-.25 G(an)-2.5 E 2.5(ys)-.15 G
(ource addresses are present in this Group Record.)-2.5 E
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 11])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(4.2.8. Multicast)72 84 R
(Addr)2.5 E(ess)-.18 E F0(The Multicast Address \214eld contains the IP\
 multicast address to which this Group Record pertains.)72 99.6 Q F1 2.5
(4.2.9. Sour)72 123.6 R(ce Addr)-.18 E(ess [i])-.18 E F0
(The Source Address [i] \214elds are a v)72 139.2 Q
(ector of n IP unicast addresses, where n is the v)-.15 E
(alue in this record')-.25 E(s)-.55 E(Number of Sources \(N\) \214eld.)
72 151.2 Q F1 2.5(4.2.10. A)72 175.2 R(uxiliary Data)-.5 E F0(The Auxil\
iary Data \214eld, if present, contains additional information pertaini\
ng to this Group Record.)72 190.8 Q(The)5 E
(protocol speci\214ed in this document, IGMPv3, does not de\214ne an)72
202.8 Q 2.5(ya)-.15 G(uxiliary data.)-2.5 E(Therefore,)5 E
(implementations of IGMPv3 MUST NO)72 214.8 Q 2.5(Ti)-.4 G(nclude an)
-2.5 E 2.5(ya)-.15 G(uxiliary data \(i.e., MUST set the Aux Data Len)
-2.5 E(\214eld to zero\) in an)72 226.8 Q 2.5(yt)-.15 G
(ransmitted Group Record, and MUST ignore an)-2.5 E 2.5(ya)-.15 G
(uxiliary data present in an)-2.5 E 2.5(yr)-.15 G(ecei)-2.5 E -.15(ve)
-.25 G(d).15 E(Group Record.)72 238.8 Q(The semantics and internal enco\
ding of the Auxiliary Data \214eld are to be de\214ned by an)5 E(y)-.15
E(future v)72 250.8 Q(ersion or e)-.15 E
(xtension of IGMP that uses this \214eld.)-.15 E F1 2.5
(4.2.11. Additional)72 274.8 R(Data)2.5 E F0(If the P)72 290.4 Q(ack)
-.15 E(et Length \214eld in the IP header of a recei)-.1 E -.15(ve)-.25
G 2.5(dR).15 G(eport indicates that there are additional octets of)-2.5
E(data present, be)72 302.4 Q(yond the last Group Record, IGMPv3 implem\
entations MUST include those octets in the)-.15 E(computation to v)72
314.4 Q(erify the recei)-.15 E -.15(ve)-.25 G 2.5(dI).15 G
(GMP Checksum, b)-2.5 E
(ut MUST otherwise ignore those additional octets.)-.2 E
(When sending a Report, an IGMPv3 implementation MUST NO)72 326.4 Q 2.5
(Ti)-.4 G(nclude additional octets be)-2.5 E(yond the last)-.15 E
(Group Record.)72 338.4 Q F1 2.5(4.2.12. Gr)72 362.4 R(oup Record T)-.18
E(ypes)-.74 E F0(There are a number of dif)72 378 Q(ferent types of Gro\
up Records that may be included in a Report message:)-.25 E 5(oA)72
393.6 S("Current-State Record" is sent by a system in response to a Que\
ry recei)-2.5 E -.15(ve)-.25 G 2.5(do).15 G 2.5(na)-2.5 G 2.5(ni)-2.5 G
(nterf)-2.5 E 2.5(ace. It)-.1 F(reports)2.5 E
(the current reception state of that interf)82 405.6 Q
(ace, with respect to a single multicast address.)-.1 E(The Record T)5 E
(ype)-.8 E(of a Current-State Record may be one of the follo)82 417.6 Q
(wing tw)-.25 E 2.5(ov)-.1 G(alues:)-2.75 E/F2 10/Courier@0 SF 6
(Value Name)94 441.6 R(and Meaning)6 E 6(----- ----------------)94 453.6
R 24(1M)106 477.6 S(ODE_IS_INCLUDE - indicates that the interface has a)
-24 E(filter mode of INCLUDE for the specified multicast)136 489.6 Q 6
(address. The)136 501.6 R(Source Address [i] fields in this Group)6 E
(Record contain the interface's source list for the)136 513.6 Q
(specified multicast address, if it is non-empty.)136 525.6 Q 24(2M)106
549.6 S(ODE_IS_EXCLUDE - indicates that the interface has a)-24 E
(filter mode of EXCLUDE for the specified multicast)136 561.6 Q 6
(address. The)136 573.6 R(Source Address [i] fields in this Group)6 E
(Record contain the interface's source list for the)136 585.6 Q
(specified multicast address, if it is non-empty.)136 597.6 Q F0
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 12])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E 5(oA)72 84 S("Filter)-2.5 E
(-Mode-Change Record" is sent by a system whene)-.2 E -.15(ve)-.25 G 2.5
(ral).15 G(ocal in)-2.5 E -.2(vo)-.4 G(cation of IPMulticastListen).2 E
(causes a change of the \214lter mode \(i.e., a change from INCLUDE to \
EXCLUDE, or from EXCLUDE to)82 96 Q(INCLUDE\), of the interf)82 108 Q
(ace-le)-.1 E -.15(ve)-.25 G 2.5(ls).15 G
(tate entry for a particular multicast address.)-2.5 E
(The Record is included)5 E(in a Report sent from the interf)82 120 Q
(ace on which the change occurred.)-.1 E(The Record T)5 E
(ype of a Filter)-.8 E(-Mode-)-.2 E
(Change Record may be one of the follo)82 132 Q(wing tw)-.25 E 2.5(ov)
-.1 G(alues:)-2.75 E/F1 10/Courier@0 SF 24(3C)106 156 S
(HANGE_TO_INCLUDE_MODE - indicates that the interface)-24 E
(has changed to INCLUDE filter mode for the specified)136 168 Q
(multicast address.)136 180 Q(The Source Address [i] fields)12 E
(in this Group Record contain the interface's new)136 192 Q
(source list for the specified multicast address,)136 204 Q
(if it is non-empty.)136 216 Q 24(4C)106 240 S
(HANGE_TO_EXCLUDE_MODE - indicates that the interface)-24 E
(has changed to EXCLUDE filter mode for the specified)136 252 Q
(multicast address.)136 264 Q(The Source Address [i] fields)12 E
(in this Group Record contain the interface's new)136 276 Q
(source list for the specified multicast address,)136 288 Q
(if it is non-empty.)136 300 Q F0 5(oA)72 315.6 S
("Source-List-Change Record" is sent by a system whene)-2.5 E -.15(ve)
-.25 G 2.5(ral).15 G(ocal in)-2.5 E -.2(vo)-.4 G
(cation of IPMulticastListen).2 E(causes a change of source list that i\
s *not* coincident with a change of \214lter mode, of the interf)82
327.6 Q(ace-le)-.1 E -.15(ve)-.25 G(l).15 E
(state entry for a particular multicast address.)82 339.6 Q
(The Record is included in a Report sent from the interf)5 E(ace)-.1 E
(on which the change occurred.)82 351.6 Q(The Record T)5 E
(ype of a Source-List-Change Record may be one of the)-.8 E(follo)82
363.6 Q(wing tw)-.25 E 2.5(ov)-.1 G(alues:)-2.75 E F1 24(5A)106 387.6 S
(LLOW_NEW_SOURCES - indicates that the Source Address)-24 E
([i] fields in this Group Record contain a list of the)136 399.6 Q
(additional sources that the system wishes to)136 411.6 Q
(hear from, for packets sent to the specified)136 423.6 Q
(multicast address.)136 435.6 Q(If the change was to an INCLUDE)12 E
(source list, these are the addresses that were added)136 447.6 Q
(to the list; if the change was to an EXCLUDE source)136 459.6 Q
(list, these are the addresses that were deleted from)136 471.6 Q
(the list.)136 483.6 Q 24(6B)106 507.6 S
(LOCK_OLD_SOURCES - indicates that the Source Address)-24 E
([i] fields in this Group Record contain a list of the)136 519.6 Q
(sources that the system no longer wishes to)136 531.6 Q
(hear from, for packets sent to the specified)136 543.6 Q
(multicast address.)136 555.6 Q(If the change was to an INCLUDE)12 E
(source list, these are the addresses that were)136 567.6 Q
(deleted from)136 579.6 Q(the list; if the change was to an)12 E
(EXCLUDE source list, these are the addresses that)136 591.6 Q
(were added to the list.)136 603.6 Q F0
(If a change of source list results in both allo)82 627.6 Q(wing ne)-.25
E 2.5(ws)-.25 G(ources and blocking old sources, then tw)-2.5 E 2.5(oG)
-.1 G(roup)-2.5 E
(Records are sent for the same multicast address, one of type ALLO)82
639.6 Q(W_NEW_SOURCES and one of type)-.35 E(BLOCK_OLD_SOURCES.)82 651.6
Q 1.6 -.8(We u)72 679.2 T
(se the term "State-Change Record" to refer to either a Filter).8 E
(-Mode-Change Record or a Source-List-)-.2 E(Change Record.)72 691.2 Q
(Unrecognized Record T)72 706.8 Q(ype v)-.8 E
(alues MUST be silently ignored.)-.25 E(Cain, Deering, Fenner)72 768 Q
2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)
-.05 F(age 13])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(4.2.13. IP)72 84 R(Sour)2.5
E(ce Addr)-.18 E(esses f)-.18 E(or Reports)-.25 E F0
(An IGMP report is sent with a v)72 99.6 Q
(alid IP source address for the destination subnet.)-.25 E
(The 0.0.0.0 source)5 E(address may be used by a system that has not ye\
t acquired an IP address.)72 111.6 Q(Note that the 0.0.0.0 source)5 E
(address may simultaneously be used by multiple systems on a LAN.)72
123.6 Q(Routers MUST accept a report with a)5 E
(source address of 0.0.0.0.)72 135.6 Q F1 2.5(4.2.14. IP)72 171.6 R
(Destination Addr)2.5 E(esses f)-.18 E(or Reports)-.25 E F0 -1.11(Ve)72
187.2 S(rsion 3 Reports are sent with an IP destination address of 224.\
0.0.22, to which all IGMPv3-capable)1.11 E(multicast routers listen.)72
199.2 Q 2.5(As)5 G(ystem that is operating in v)-2.5 E(ersion 1 or v)
-.15 E(ersion 2 compatibility modes sends)-.15 E -.15(ve)72 211.2 S
(rsion 1 or v).15 E(ersion 2 Reports to the multicast group speci\214ed\
 in the Group Address \214eld of the Report.)-.15 E(In)5 E
(addition, a system MUST accept and process an)72 223.2 Q 2.5(yv)-.15 G
(ersion 1 or v)-2.65 E(ersion 2 Report whose IP Destination)-.15 E
(Address \214eld contains *an)72 235.2 Q
(y* of the addresses \(unicast or multicast\) assigned to the interf)
-.15 E(ace on which the)-.1 E(Report arri)72 247.2 Q -.15(ve)-.25 G(s.)
.15 E F1 2.5(4.2.15. Notation)72 271.2 R -.25(fo)2.5 G 2.5(rG).25 G -.18
(ro)-2.5 G(up Records).18 E F0
(In the rest of this document, we use the follo)72 286.8 Q
(wing notation to describe the contents of a Group Record)-.25 E
(pertaining to a particular multicast address:)72 298.8 Q/F2 10
/Courier@0 SF(IS_IN \( x \))96 322.8 Q 12(-T)12 G
(ype MODE_IS_INCLUDE, source addresses x)-12 E(IS_EX \( x \))96 334.8 Q
12(-T)12 G(ype MODE_IS_EXCLUDE, source addresses x)-12 E(TO_IN \( x \))
96 346.8 Q 12(-T)12 G(ype CHANGE_TO_INCLUDE_MODE, source addresses x)-12
E(TO_EX \( x \))96 358.8 Q 12(-T)12 G
(ype CHANGE_TO_EXCLUDE_MODE, source addresses x)-12 E(ALLOW \( x \))96
370.8 Q 12(-T)12 G(ype ALLOW_NEW_SOURCES, source addresses x)-12 E
(BLOCK \( x \))96 382.8 Q 12(-T)12 G
(ype BLOCK_OLD_SOURCES, source addresses x)-12 E F0(where x is either:)
72 406.8 Q 5(oa)72 422.4 S(capital letter \(e.g., "A"\) to represent th\
e set of source addresses, or)-2.5 E 5(oa)72 438 S(set e)-2.5 E(xpressi\
on \(e.g., "A+B"\), where "A+B" means the union of sets A and B,)-.15 E
("A*B" means the)5 E
(intersection of sets A and B, and "A-B" means the remo)82 450 Q -.25
(va)-.15 G 2.5(lo).25 G 2.5(fa)-2.5 G(ll elements of set B from set A.)
-2.5 E F1 2.5(4.2.16. Membership)72 486 R(Report Size)2.5 E F0(If the s\
et of Group Records required in a Report does not \214t within the size\
 limit of a single Report message)72 501.6 Q
(\(as determined by the MTU of the netw)72 513.6 Q
(ork on which it will be sent\), the Group Records are sent in as man)
-.1 E(y)-.15 E(Report messages as needed to report the entire set.)72
525.6 Q(If a single Group Record contains so man)72 541.2 Q 2.5(ys)-.15
G(ource addresses that it does not \214t within the size limit of a)-2.5
E(single Report message, if its T)72 553.2 Q
(ype is not MODE_IS_EXCLUDE or CHANGE_T)-.8 E(O_EXCLUDE_MODE, it)-.18 E
(is split into multiple Group Records, each containing a dif)72 565.2 Q
(ferent subset of the source addresses and each)-.25 E
(sent in a separate Report message.)72 577.2 Q(If its T)5 E
(ype is MODE_IS_EXCLUDE or)-.8 E(CHANGE_T)72 589.2 Q
(O_EXCLUDE_MODE, a single Group Record is sent, containing as man)-.18 E
2.5(ys)-.15 G(ource addresses as)-2.5 E(can \214t, and the remaining so\
urce addresses are not reported; though the choice of which sources to \
report is)72 601.2 Q(arbitrary)72 613.2 Q 2.5(,i)-.65 G 2.5(ti)-2.5 G
2.5(sp)-2.5 G(referable to report the same set of sources in each subse\
quent report, rather than reporting)-2.5 E(dif)72 625.2 Q
(ferent sources each time.)-.25 E F1 2.5(5. DESCRIPTION)72 661.2 R
(OF THE PR)2.5 E -1.88 -.4(OT O)-.3 H(COL FOR GR).4 E(OUP MEMBERS)-.3 E
F0(IGMP is an asymmetric protocol, specifying separate beha)72 676.8 Q
(viors for group members -- that is, hosts or)-.2 E
(routers that wish to recei)72 688.8 Q .3 -.15(ve m)-.25 H
(ulticast pack).15 E(ets -- and multicast routers.)-.1 E
(This section describes the part of)5 E(IGMPv3 that applies to all grou\
p members. \(Note that a multicast router that is also a group member)72
700.8 Q(performs both parts of IGMPv3, recei)72 712.8 Q
(ving and responding to its o)-.25 E
(wn IGMP message transmissions as well)-.25 E(Cain, Deering, Fenner)72
768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43
(arajan [P)-.05 F(age 14])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(as those of its neighbors.)72 84 Q
(The multicast router part of IGMPv3 is described in section 6.\))5 E
2.5(As)72 99.6 S
(ystem performs the protocol described in this section o)-2.5 E -.15(ve)
-.15 G 2.5(ra).15 G(ll interf)-2.5 E
(aces on which multicast reception is)-.1 E(supported, e)72 111.6 Q -.15
(ve)-.25 G 2.5(ni).15 G 2.5(fm)-2.5 G(ore than one of those interf)-2.5
E(aces is connected to the same netw)-.1 E(ork.)-.1 E -.15(Fo)72 127.2 S
2.5(ri).15 G(nteroperability with multicast routers running older v)-2.5
E(ersions of IGMP)-.15 E 2.5(,s)-1.11 G(ystems maintain a)-2.5 E
(MulticastRouterV)72 139.2 Q(ersion v)-1.11 E(ariable for each interf)
-.25 E(ace on which multicast reception is supported.)-.1 E
(This section)5 E(describes the beha)72 151.2 Q
(vior of group member systems on interf)-.2 E
(aces for which MulticastRouterV)-.1 E(ersion = 3.)-1.11 E(The)5 E
(algorithm for determining MulticastRouterV)72 163.2 Q
(ersion, and the beha)-1.11 E(vior for v)-.2 E
(ersions other than 3, are described)-.15 E(in section 7.)72 175.2 Q(Th\
e all-systems multicast address, 224.0.0.1, is handled as a special cas\
e.)72 190.8 Q(On all systems -- that is all hosts)5 E
(and routers, including multicast routers -- reception of pack)72 202.8
Q(ets destined to the all-systems multicast address,)-.1 E
(from all sources, is permanently enabled on all interf)72 214.8 Q
(aces on which multicast reception is supported.)-.1 E(No)5 E
(IGMP messages are e)72 226.8 Q -.15(ve)-.25 G 2.5(rs).15 G(ent re)-2.5
E -.05(ga)-.15 G(rding the all-systems multicast address.).05 E
(There are tw)72 242.4 Q 2.5(ot)-.1 G(ypes of e)-2.5 E -.15(ve)-.25 G
(nts that trigger IGMPv3 protocol actions on an interf).15 E(ace:)-.1 E
5(oa)72 258 S(change of the interf)-2.5 E
(ace reception state, caused by a local in)-.1 E -.2(vo)-.4 G
(cation of IPMulticastListen.).2 E 5(or)72 273.6 S(eception of a Query)
-5 E(.)-.65 E(\(Recei)72 289.2 Q -.15(ve)-.25 G 2.5(dI).15 G
(GMP messages of types other than Query are silently ignored, e)-2.5 E
(xcept as required for)-.15 E(interoperation with earlier v)72 301.2 Q
(ersions of IGMP)-.15 E(.\))-1.11 E(The follo)72 316.8 Q
(wing subsections describe the actions to be tak)-.25 E
(en for each of these tw)-.1 E 2.5(oc)-.1 G 2.5(ases. In)-2.5 F(those)
2.5 E(descriptions, timer and counter names appear in square brack)72
328.8 Q 2.5(ets. The)-.1 F(def)2.5 E(ault v)-.1 E
(alues for those timers and)-.25 E
(counters are speci\214ed in section 8.)72 340.8 Q/F1 10/Times-Bold@0 SF
2.5(5.1. Action)72 376.8 R(on Change of Interface State)2.5 E F0(An in)
72 392.4 Q -.2(vo)-.4 G(cation of IPMulticastListen may cause the multi\
cast reception state of an interf).2 E(ace to change,)-.1 E
(according to the rules in section 3.2.)72 404.4 Q(Each such change af)5
E(fects the per)-.25 E(-interf)-.2 E(ace entry for a single multicast)
-.1 E(address.)72 416.4 Q 2.5(Ac)72 432 S(hange of interf)-2.5 E(ace st\
ate causes the system to immediately transmit a State-Change Report fro\
m that)-.1 E(interf)72 444 Q 2.5(ace. The)-.1 F(type and contents of th\
e Group Record\(s\) in that Report are determined by comparing the)2.5 E
(\214lter mode and source list for the af)72 456 Q
(fected multicast address before and after the change, according to the)
-.25 E(table belo)72 468 Q 3.8 -.65(w. I)-.25 H 2.5(fn).65 G 2.5(oi)-2.5
G(nterf)-2.5 E(ace state e)-.1 E
(xisted for that multicast address before the change \(i.e., the change)
-.15 E(consisted of creating a ne)72 480 Q 2.5(wp)-.25 G(er)-2.5 E
(-interf)-.2 E(ace record\), or if no state e)-.1 E
(xists after the change \(i.e., the change)-.15 E
(consisted of deleting a per)72 492 Q(-interf)-.2 E
(ace record\), then the "non-e)-.1 E(xistent" state is considered to ha)
-.15 E .3 -.15(ve a \214)-.2 H(lter mode).15 E
(of INCLUDE and an empty source list.)72 504 Q/F2 10/Courier@0 SF
(Old State)84 528 Q(New State)54 E(State-Change Record Sent)54 E 48
(--------- --------- ------------------------)84 540 R(INCLUDE \(A\))84
564 Q(INCLUDE \(B\))42 E(ALLOW \(B-A\), BLOCK \(A-B\))42 E
(EXCLUDE \(A\))84 588 Q(EXCLUDE \(B\))42 E(ALLOW \(A-B\), BLOCK \(B-A\))
42 E(INCLUDE \(A\))84 612 Q(EXCLUDE \(B\))42 E(TO_EX \(B\))42 E
(EXCLUDE \(A\))84 636 Q(INCLUDE \(B\))42 E(TO_IN \(B\))42 E F0
(If the computed source list for either an ALLO)72 651.6 Q 2.5(Wo)-.35 G
2.5(raB)-2.5 G(LOCK State-Change Record is empty)-2.5 E 2.5(,t)-.65 G
(hat record is)-2.5 E(omitted from the Report message.)72 663.6 Q 1.6
-.8(To c)72 679.2 T -.15(ove).8 G 2.5(rt).15 G(he possibility of the St\
ate-Change Report being missed by one or more multicast routers, it is)
-2.5 E(retransmitted [Rob)72 691.2 Q(ustness V)-.2 E
(ariable] - 1 more times, at interv)-1.11 E
(als chosen at random from the range \(0,)-.25 E
([Unsolicited Report Interv)72 703.2 Q(al]\).)-.25 E
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 15])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(If more changes to the same interf)72 84 Q(ace state\
 entry occur before all the retransmissions of the State-Change)-.1 E
(Report for the \214rst change ha)72 96 Q .3 -.15(ve b)-.2 H
(een completed, each such additional change triggers the immediate).15 E
(transmission of a ne)72 108 Q 2.5(wS)-.25 G(tate-Change Report.)-2.5 E
(The contents of the ne)72 123.6 Q 2.5(wt)-.25 G
(ransmitted report are calculated as follo)-2.5 E 2.5(ws. As)-.25 F -.1
(wa)2.5 G 2.5(sd).1 G(one with the \214rst report, the)-2.5 E(interf)72
135.6 Q(ace state for the af)-.1 E(fected group before and after the la\
test change is compared. The report records)-.25 E -.15(ex)72 147.6 S
(pressing the dif).15 E(ference are b)-.25 E
(uilt according to the table abo)-.2 E -.15(ve)-.15 G 5(.H).15 G -.25
(ow)-5 G -2.15 -.25(ev e).25 H 2.5(rt).25 G
(hese records are not transmitted)-2.5 E(in a message b)72 159.6 Q
(ut instead mer)-.2 E
(ged with the contents of the pending report, to create the ne)-.18 E
2.5(wS)-.25 G(tate-Change)-2.5 E(report. The rules for mer)72 171.6 Q
(ging the dif)-.18 E
(ference report resulting from the state change and the pending report)
-.25 E(are described belo)72 183.6 Q -.65(w.)-.25 G
(The transmission of the mer)72 199.2 Q(ged State-Change Report termina\
tes retransmissions of the earlier State-Change)-.18 E(Reports for the \
same multicast address, and becomes the \214rst of [Rob)72 211.2 Q
(ustness V)-.2 E(ariable] transmissions of)-1.11 E
(State-Change Reports.)72 223.2 Q
(Each time a source is included in the dif)72 238.8 Q
(ference report calculated abo)-.25 E -.15(ve)-.15 G 2.5(,r).15 G
(etransmission state for that source)-2.5 E
(needs to be maintained until [Rob)72 250.8 Q(ustness V)-.2 E
(ariable] State-Change reports ha)-1.11 E .3 -.15(ve b)-.2 H
(een sent by the host.).15 E(This is)5 E
(done in order to ensure that a series of successi)72 262.8 Q .3 -.15
(ve s)-.25 H(tate changes do not break the protocol rob).15 E(ustness.)
-.2 E(If the interf)72 278.4 Q
(ace reception-state change that triggers the ne)-.1 E 2.5(wr)-.25 G
(eport is a \214lter)-2.5 E(-mode change, then the ne)-.2 E(xt)-.15 E
([Rob)72 290.4 Q(ustness V)-.2 E
(ariable] State-Change Reports will include a Filter)-1.11 E
(-Mode-Change record. This applies e)-.2 E -.15(ve)-.25 G 2.5(ni).15 G
(f)-2.5 E(an)72 302.4 Q 2.5(yn)-.15 G(umber of source-list changes occu\
r in that period. The host has to maintain retransmission state for the)
-2.5 E(group until the [Rob)72 314.4 Q(ustness V)-.2 E
(ariable] State-Change reports ha)-1.11 E .3 -.15(ve b)-.2 H(een sent.)
.15 E(When [Rob)5 E(ustness V)-.2 E(ariable])-1.11 E
(State-Change reports with Filter)72 326.4 Q(-Mode-Change records ha)-.2
E .3 -.15(ve b)-.2 H(een transmitted after the last \214lter).15 E
(-mode)-.2 E(change, and if source-list changes to the interf)72 338.4 Q
(ace reception ha)-.1 E .3 -.15(ve s)-.2 H
(cheduled additional reports, then the ne).15 E(xt)-.15 E
(State-Change report will include Source-List-Change records.)72 350.4 Q
(Each time a State-Change Report is transmitted, the contents are deter\
mined as follo)72 366 Q(ws. If the report should)-.25 E
(contain a Filter)72 378 Q
(-Mode-Change record, then if the current \214lter)-.2 E
(-mode of the interf)-.2 E(ace is INCLUDE, a T)-.1 E(O_IN)-.18 E
(record is included in the report, otherwise a T)72 390 Q
(O_EX record is included. If instead the report should contain)-.18 E
(Source-List-Change records, an ALLO)72 402 Q 2.5(Wa)-.35 G
(nd a BLOCK record are included.)-2.5 E(The contents of these records)5
E(are b)72 414 Q(uilt according to the table belo)-.2 E -.65(w.)-.25 G
/F1 10/Courier@0 SF 12(Record Sources)84 438 R(included)6 E 12
(------ ----------------)84 450 R 18(TO_IN All)84 462 R
(in the current interface state that must be forwarded)6 E 18(TO_EX All)
84 474 R(in the current interface state that must be blocked)6 E 18
(ALLOW All)84 486 R(with retransmission state that must be forwarded)6 E
18(BLOCK All)84 498 R(with retransmission state that must be blocked)6 E
F0(If the computed source list for either an ALLO)72 513.6 Q 2.5(Wo)-.35
G 2.5(raB)-2.5 G(LOCK record is empty)-2.5 E 2.5(,t)-.65 G
(hat record is omitted from)-2.5 E(the State-Change report.)72 525.6 Q
(Note: When the \214rst State-Change report is sent, the non-e)72 541.2
Q(xistent pending report to mer)-.15 E(ge with, can be)-.18 E
(treated as a source-change report with empty ALLO)72 553.2 Q 2.5(Wa)
-.35 G(nd BLOCK records \(no sources ha)-2.5 E -.15(ve)-.2 G
(retransmission state\).)72 565.2 Q/F2 10/Times-Bold@0 SF 2.5
(5.2. Action)72 601.2 R(on Reception of a Query)2.5 E F0
(When a system recei)72 616.8 Q -.15(ve)-.25 G 2.5(saQ).15 G(uery)-2.5 E
2.5(,i)-.65 G 2.5(td)-2.5 G(oes not respond immediately)-2.5 E 5(.I)-.65
G(nstead, it delays its response by a)-5 E
(random amount of time, bounded by the Max Resp T)72 628.8 Q(ime v)-.35
E(alue deri)-.25 E -.15(ve)-.25 G 2.5(df).15 G
(rom the Max Resp Code in the)-2.5 E(recei)72 640.8 Q -.15(ve)-.25 G 2.5
(dQ).15 G(uery message.)-2.5 E 2.5(As)5 G(ystem may recei)-2.5 E .3 -.15
(ve a v)-.25 H(ariety of Queries on dif)-.1 E(ferent interf)-.25 E
(aces and of dif)-.1 E(ferent)-.25 E(kinds \(e.g., General Queries, Gro\
up-Speci\214c Queries, and Group-and- Source-Speci\214c Queries\), each\
 of)72 652.8 Q(which may require its o)72 664.8 Q(wn delayed response.)
-.25 E(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)
-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 16])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(Before scheduling a response to a Query)72 84 Q 2.5
(,t)-.65 G(he system must \214rst consider pre)-2.5 E
(viously scheduled pending)-.25 E(responses and in man)72 96 Q 2.5(yc)
-.15 G(ases schedule a combined response. Therefore, the system must be\
 able to maintain)-2.5 E(the follo)72 108 Q(wing state:)-.25 E 5(oA)72
123.6 S(timer per interf)-2.5 E
(ace for scheduling responses to General Queries.)-.1 E 5(oA)72 139.2 S
(per)-2.5 E(-group and interf)-.2 E(ace timer for scheduling responses \
to Group-Speci\214c and Group-and-Source-)-.1 E(Speci\214c Queries.)82
151.2 Q 5(oA)72 166.8 S(per)-2.5 E(-group and interf)-.2 E(ace list of \
sources to be reported in the response to a Group-and-Source-Speci\214c)
-.1 E(Query)82 178.8 Q(.)-.65 E(When a ne)72 194.4 Q 2.5(wQ)-.25 G
(uery with the Router)-2.5 E(-Alert option arri)-.2 E -.15(ve)-.25 G 2.5
(so).15 G 2.5(na)-2.5 G 2.5(ni)-2.5 G(nterf)-2.5 E(ace, pro)-.1 E
(vided the system has state to)-.15 E(report, a delay for a response is\
 randomly selected in the range \(0, [Max Resp T)72 206.4 Q
(ime]\) where Max Resp)-.35 E -.35(Ti)72 218.4 S(me is deri).35 E -.15
(ve)-.25 G 2.5(df).15 G(rom Max Resp Code in the recei)-2.5 E -.15(ve)
-.25 G 2.5(dQ).15 G(uery message.)-2.5 E(The follo)5 E
(wing rules are then used to)-.25 E(determine if a Report needs to be s\
cheduled and the type of Report to schedule.)72 230.4 Q
(The rules are considered in)5 E
(order and only the \214rst matching rule is applied.)72 242.4 Q 5
(1. If)72 258 R(there is a pending response to a pre)2.5 E
(vious General Query scheduled sooner than the selected delay)-.25 E 2.5
(,n)-.65 G(o)-2.5 E(additional response needs to be scheduled.)87 270 Q
5(2. If)72 285.6 R(the recei)2.5 E -.15(ve)-.25 G 2.5(dQ).15 G
(uery is a General Query)-2.5 E 2.5(,t)-.65 G(he interf)-2.5 E
(ace timer is used to schedule a response to the)-.1 E
(General Query after the selected delay)87 297.6 Q 5(.A)-.65 G .3 -.15
(ny p)-5 H(re).15 E(viously pending response to a General Query is)-.25
E(canceled.)87 309.6 Q 5(3. If)72 325.2 R(the recei)2.5 E -.15(ve)-.25 G
2.5(dQ).15 G(uery is a Group-Speci\214c Query or a Group-and-Source-Spe\
ci\214c Query and there is no)-2.5 E(pending response to a pre)87 337.2
Q(vious Query for this group, then the group timer is used to schedule \
a report.)-.25 E(If the recei)87 349.2 Q -.15(ve)-.25 G 2.5(dQ).15 G
(uery is a Group-and-Source-Speci\214c Query)-2.5 E 2.5(,t)-.65 G
(he list of queried sources is recorded to be)-2.5 E
(used when generating a response.)87 361.2 Q 5(4. If)72 376.8 R
(there already is a pending response to a pre)2.5 E
(vious Query scheduled for this group, and either the ne)-.25 E(w)-.25 E
(Query is a Group-Speci\214c Query or the recorded source-list associat\
ed with the group is empty)87 388.8 Q 2.5(,t)-.65 G(hen the)-2.5 E(grou\
p source-list is cleared and a single response is scheduled using the g\
roup timer)87 400.8 Q 2.5(.T)-.55 G(he ne)-2.5 E 2.5(wr)-.25 G(esponse)
-2.5 E(is scheduled to be sent at the earliest of the remaining time fo\
r the pending report and the selected)87 412.8 Q(delay)87 424.8 Q(.)-.65
E 5(5. If)72 440.4 R(the recei)2.5 E -.15(ve)-.25 G 2.5(dQ).15 G(uery i\
s a Group-and-Source-Speci\214c Query and there is a pending response f\
or this)-2.5 E(group with a non-empty source-list, then the group sourc\
e list is augmented to contain the list of)87 452.4 Q(sources in the ne)
87 464.4 Q 2.5(wQ)-.25 G
(uery and a single response is scheduled using the group timer)-2.5 E
2.5(.T)-.55 G(he ne)-2.5 E 2.5(wr)-.25 G(esponse is)-2.5 E(scheduled to\
 be sent at the earliest of the remaining time for the pending report a\
nd the selected delay)87 476.4 Q(.)-.65 E
(When the timer in a pending response record e)72 492 Q
(xpires, the system transmits, on the associated interf)-.15 E(ace, one)
-.1 E(or more Report messages carrying one or more Current-State Record\
s \(see section 4.2.12\), as follo)72 504 Q(ws:)-.25 E 5(1. If)72 519.6
R(the e)2.5 E(xpired timer is the interf)-.15 E(ace timer \(i.e., it is\
 a pending response to a General Query\), then one)-.1 E(Current-State \
Record is sent for each multicast address for which the speci\214ed int\
erf)87 531.6 Q(ace has reception)-.1 E
(state, as described in section 3.2.)87 543.6 Q
(The Current-State Record carries the multicast address and its)5 E(ass\
ociated \214lter mode \(MODE_IS_INCLUDE or MODE_IS_EXCLUDE\) and source\
 list.)87 555.6 Q(Multiple)5 E(Current-State Records are pack)87 567.6 Q
(ed into indi)-.1 E(vidual Report messages, to the e)-.25 E
(xtent possible.)-.15 E(This nai)87 583.2 Q .3 -.15(ve a)-.25 H
(lgorithm may result in b).15 E(ursts of pack)-.2 E
(ets when a system is a member of a lar)-.1 E(ge number of)-.18 E 2.5
(groups. Instead)87 595.2 R(of using a single interf)2.5 E(ace timer)-.1
E 2.5(,i)-.4 G(mplementations are recommended to spread)-2.5 E
(transmission of such Report messages o)87 607.2 Q -.15(ve)-.15 G 2.5
(rt).15 G(he interv)-2.5 E(al \(0, [Max Resp T)-.25 E 2.5(ime]\). Note)
-.35 F(that an)2.5 E 2.5(ys)-.15 G(uch)-2.5 E(implementation MUST a)87
619.2 Q -.2(vo)-.2 G(id the "ack-implosion" problem, i.e. MUST NO).2 E
2.5(Ts)-.4 G(end a Report immediately)-2.5 E
(on reception of a General Query)87 631.2 Q(.)-.65 E 5(2. If)72 646.8 R
(the e)2.5 E(xpired timer is a group timer and the list of recorded sou\
rces for the that group is empty \(i.e., it is)-.15 E 2.5(ap)87 658.8 S
(ending response to a Group-Speci\214c Query\), then if and only if the\
 interf)-2.5 E(ace has reception state for)-.1 E(that group address, a \
single Current-State Record is sent for that address.)87 670.8 Q
(The Current-State Record)5 E(carries the multicast address and its ass\
ociated \214lter mode \(MODE_IS_INCLUDE or)87 682.8 Q
(MODE_IS_EXCLUDE\) and source list.)87 694.8 Q(Cain, Deering, Fenner)72
768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43
(arajan [P)-.05 F(age 17])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E 5(3. If)72 84 R(the e)2.5 E(xpired timer is a group \
timer and the list of recorded sources for that group is non-empty \(i.\
e., it)-.15 E(is a pending response to a Group-and-Source-Speci\214c Qu\
ery\), then if and only if the interf)87 96 Q(ace has)-.1 E(reception s\
tate for that group address, the contents of the responding Current-Sta\
te Record is)87 108 Q(determined from the interf)87 120 Q
(ace state and the pending response record, as speci\214ed in the follo)
-.1 E(wing table:)-.25 E/F1 10/Courier@0 SF(set of sources in the)225
144 Q(interface state)111 156 Q(pending response record)18 E
(Current-State Record)18 E 12
(--------------- ----------------------- --------------------)111 168 R
(INCLUDE \(A\))117 192 Q 114(BI)96 G(S_IN \(A*B\))-114 E(EXCLUDE \(A\))
117 216 Q 114(BI)96 G(S_IN \(B-A\))-114 E F0(If the resulting Current-S\
tate Record has an empty set of source addresses, then no response is s\
ent.)72 231.6 Q(Finally)72 247.2 Q 2.5(,a)-.65 G(fter an)-2.5 E 2.5(yr)
-.15 G(equired Report messages ha)-2.5 E .3 -.15(ve b)-.2 H
(een generated, the source lists associated with an).15 E(y)-.15 E
(reported groups are cleared.)72 259.2 Q/F2 10/Times-Bold@0 SF 2.5
(6. DESCRIPTION)72 295.2 R(OF THE PR)2.5 E -1.88 -.4(OT O)-.3 H
(COL FOR MUL).4 E(TICAST R)-.92 E(OUTERS)-.3 E F0(The purpose of IGMP i\
s to enable each multicast router to learn, for each of its directly at\
tached netw)72 310.8 Q(orks,)-.1 E(which multicast addresses are of int\
erest to the systems attached to those netw)72 322.8 Q 2.5(orks. IGMP)
-.1 F -.15(ve)2.5 G(rsion 3 adds).15 E
(the capability for a multicast router to also learn)72 334.8 Q
(which *sources* are of interest to neighboring systems,)5 E(for pack)72
346.8 Q(ets sent to an)-.1 E 2.5(yp)-.15 G(articular multicast address.)
-2.5 E(The information g)5 E(athered by IGMP is pro)-.05 E(vided to)-.15
E(whiche)72 358.8 Q -.15(ve)-.25 G 2.5(rm).15 G
(ulticast routing protocol is being used by the router)-2.5 E 2.5(,i)-.4
G 2.5(no)-2.5 G(rder to ensure that multicast pack)-2.5 E(ets)-.1 E
(are deli)72 370.8 Q -.15(ve)-.25 G(red to all netw).15 E
(orks where there are interested recei)-.1 E -.15(ve)-.25 G(rs.).15 E(T\
his section describes the part of IGMPv3 that is performed by multicast\
 routers.)72 386.4 Q(Multicast routers may)5 E(also themselv)72 398.4 Q
(es become members of multicast groups, and therefore also perform the \
group member part of)-.15 E(IGMPv3, described in section 5.)72 410.4 Q
2.5(Am)72 426 S
(ulticast router performs the protocol described in this section o)-2.5
E -.15(ve)-.15 G 2.5(re).15 G(ach of its directly-attached)-2.5 E(netw)
72 438 Q 2.5(orks. If)-.1 F 2.5(am)2.5 G
(ulticast router has more than one interf)-2.5 E(ace to the same netw)
-.1 E(ork, it only needs to operate)-.1 E(this protocol o)72 450 Q -.15
(ve)-.15 G 2.5(ro).15 G(ne of those interf)-2.5 E 2.5(aces. On)-.1 F
(each interf)2.5 E(ace o)-.1 E -.15(ve)-.15 G 2.5(rw).15 G
(hich this protocol is being run, the)-2.5 E(router MUST enable recepti\
on of multicast address 224.0.0.22, from all sources \(and MUST perform\
 the)72 462 Q
(group member part of IGMPv3 for that address on that interf)72 474 Q
(ace\).)-.1 E(Multicast routers need to kno)72 489.6 Q 2.5(wo)-.25 G
(nly that *at least one* system on an attached netw)-2.5 E
(ork is interested in)-.1 E(pack)72 501.6 Q(ets to a particular multica\
st address from a particular source; a multicast router is not required\
 to k)-.1 E(eep)-.1 E(track of the interests of each indi)72 513.6 Q
(vidual neighboring system.)-.25 E(\(Ho)5 E(we)-.25 E -.15(ve)-.25 G .8
-.4(r, s).15 H(ee Appendix A.2 point 1 for).4 E(discussion.\))72 525.6 Q
(IGMPv3 is backw)72 541.2 Q(ard compatible with pre)-.1 E(vious v)-.25 E
(ersions of the IGMP protocol.)-.15 E(In order to remain)5 E(backw)72
553.2 Q(ard compatible with older IGMP systems, IGMPv3 multicast router\
s MUST also implement v)-.1 E(ersions)-.15 E 2.5(1a)72 565.2 S
(nd 2 of the protocol \(see section 7\).)-2.5 E F2 2.5(6.1. Conditions)
72 601.2 R -.25(fo)2.5 G 2.5(rI).25 G(GMP Queries)-2.5 E F0(Multicast r\
outers send General Queries periodically to request group membership in\
formation from an)72 616.8 Q(attached netw)72 628.8 Q 2.5(ork. These)-.1
F(queries are used to b)2.5 E
(uild and refresh the group membership state of systems on)-.2 E
(attached netw)72 640.8 Q 2.5(orks. Systems)-.1 F(respond to these quer\
ies by reporting their group membership state \(and their)2.5 E(desired\
 set of sources\) with Current-State Group Records in IGMPv3 Membership\
 Reports.)72 652.8 Q(As a member of a multicast group, a system may e)72
668.4 Q(xpress interest in recei)-.15 E(ving or not recei)-.25 E
(ving traf)-.25 E(\214c from)-.25 E(particular sources.)72 680.4 Q(As t\
he desired reception state of a system changes, it reports these change\
s using Filter)5 E(-)-.2 E
(Mode-Change Records or Source-List-Change Records.)72 692.4 Q
(These records indicate an e)5 E(xplicit state change in)-.15 E 2.5(ag)
72 704.4 S(roup at a system in either the group record')-2.5 E 2.5(ss)
-.55 G(ource list or its \214lter)-2.5 E 2.5(-mode. When)-.2 F 2.5(ag)
2.5 G(roup membership is)-2.5 E(terminated at a system or traf)72 716.4
Q(\214c from a particular source is no longer desired, a multicast rout\
er must query)-.25 E(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)
-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 18])-.15
E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(for other members of the group or listeners of the s\
ource before deleting the group \(or source\) and pruning)72 84 Q
(its traf)72 96 Q(\214c.)-.25 E 1.6 -.8(To e)72 111.6 T
(nable all systems on a netw).8 E
(ork to respond to changes in group membership, multicast routers send)
-.1 E(speci\214c queries.)72 123.6 Q 2.5(AG)5 G
(roup- Speci\214c Query is sent to v)-2.5 E
(erify there are no systems that desire reception of the)-.15 E
(speci\214ed group or to "reb)72 135.6 Q
(uild" the desired reception state for a particular group.)-.2 E
(Group-Speci\214c Queries)5 E(are sent when a router recei)72 147.6 Q
-.15(ve)-.25 G 2.5(saS).15 G
(tate-Change record indicating a system is lea)-2.5 E(ving a group.)-.2
E 2.5(AG)72 163.2 S(roup-and-Source Speci\214c Query is used to v)-2.5 E
(erify there are no systems on a netw)-.15 E(ork which desire to)-.1 E
(recei)72 175.2 Q .3 -.15(ve t)-.25 H(raf).15 E
(\214c from a set of sources.)-.25 E(Group-and-Source Speci\214c Querie\
s list sources for a particular group)5 E(which ha)72 187.2 Q .3 -.15
(ve b)-.2 H(een requested to no longer be forw).15 E 2.5(arded. This)-.1
F(query is sent by a multicast router to learn if)2.5 E(an)72 199.2 Q
2.5(ys)-.15 G(ystems desire reception of pack)-2.5 E(ets to the speci\
\214ed group address from the speci\214ed source addresses.)-.1 E(Group\
-and-Source Speci\214c Queries are only sent in response to State-Chang\
e Records and ne)72 211.2 Q -.15(ve)-.25 G 2.5(ri).15 G(n)-2.5 E
(response to Current-State Records.)72 223.2 Q
(Section 4.1.11 describes each query in more detail.)5 E/F1 10
/Times-Bold@0 SF 2.5(6.2. IGMP)72 259.2 R
(State Maintained by Multicast Routers)2.5 E F0
(Multicast routers implementing IGMPv3 k)72 274.8 Q
(eep state per group per attached netw)-.1 E 2.5(ork. This)-.1 F
(group state)2.5 E(consists of a \214lter)72 286.8 Q
(-mode, a list of sources, and v)-.2 E(arious timers.)-.25 E -.15(Fo)5 G
2.5(re).15 G(ach attached netw)-2.5 E(ork running IGMP)-.1 E 2.5(,a)
-1.11 G
(multicast router records the desired reception state for that netw)72
298.8 Q(ork.)-.1 E
(That state conceptually consists of a set of records of the form:)72
310.8 Q(\(multicast address, group timer)87 334.8 Q 2.5<2c8c>-.4 G(lter)
-2.5 E(-mode, \(source records\)\))-.2 E
(Each source record is of the form:)72 350.4 Q
(\(source address, source timer\))87 374.4 Q(If all sources within a gi)
72 390 Q -.15(ve)-.25 G 2.5(ng).15 G
(roup are desired, an empty source record list is k)-2.5 E
(ept with \214lter)-.1 E(-mode set to)-.2 E 2.5(EXCLUDE. This)72 402 R
(means hosts on this netw)2.5 E(ork w)-.1 E
(ant all sources for this group to be forw)-.1 E 2.5(arded. This)-.1 F
(is the)2.5 E(IGMPv3 equi)72 414 Q -.25(va)-.25 G
(lent to a IGMPv1 or IGMPv2 group join.).25 E F1 2.5
(6.2.1. De\214nition)72 450 R(of Router Filter)2.5 E(-Mode)-.37 E F0 1.6
-.8(To r)72 465.6 T(educe internal state, IGMPv3 routers k).8 E
(eep a \214lter)-.1 E(-mode per group per attached netw)-.2 E 2.5
(ork. This)-.1 F(\214lter)2.5 E(-)-.2 E(mode is used to condense the to\
tal desired reception state of a group to a minimum set such that all)72
477.6 Q(systems' memberships are satis\214ed.)72 489.6 Q(This \214lter)5
E(-mode may change in response to the reception of particular)-.2 E
(types of group records or when certain timer conditions occur)72 501.6
Q 5(.I)-.55 G 2.5(nt)-5 G(he follo)-2.5 E
(wing sections, we use the term)-.25 E("router \214lter)72 513.6 Q
(-mode" to refer to the \214lter)-.2 E
(-mode of a particular group within a router)-.2 E 5(.S)-.55 G
(ection 6.4 describes)-5 E(the changes of a router \214lter)72 525.6 Q
(-mode per group record recei)-.2 E -.15(ve)-.25 G(d.).15 E
(Conceptually)72 541.2 Q 2.5(,w)-.65 G(hen a group record is recei)-2.5
E -.15(ve)-.25 G(d, the router \214lter).15 E
(-mode for that group is updated to co)-.2 E -.15(ve)-.15 G 2.5(ra).15 G
(ll)-2.5 E(the requested sources using the least amount of state.)72
553.2 Q(As a rule, once a group record with a \214lter)5 E(-mode of)-.2
E(EXCLUDE is recei)72 565.2 Q -.15(ve)-.25 G(d, the router \214lter).15
E(-mode for that group will be EXCLUDE.)-.2 E(When a router \214lter)72
580.8 Q
(-mode for a group is EXCLUDE, the source record list contains tw)-.2 E
2.5(ot)-.1 G(ypes of sources.)-2.5 E(The \214rst type is the set which \
represents con\215icts in the desired reception state; this set must be\
 forw)72 592.8 Q(arded)-.1 E(by some router on the netw)72 604.8 Q 2.5
(ork. The)-.1 F(second type is the set of sources which hosts ha)2.5 E
.3 -.15(ve r)-.2 H(equested to not be).15 E(forw)72 616.8 Q 2.5
(arded. Appendix)-.1 F 2.5(Ad)2.5 G(escribes the reasons for k)-2.5 E
(eeping this second set when in EXCLUDE mode.)-.1 E
(When a router \214lter)72 632.4 Q(-mode for a group is INCLUDE, the so\
urce record list is the list of sources desired for)-.2 E(the group. Th\
is is the total desired set of sources for that group. Each source in t\
he source record list must)72 644.4 Q(be forw)72 656.4 Q
(arded by some router on the netw)-.1 E(ork.)-.1 E
(Because a reported group record with a \214lter)72 672 Q
(-mode of EXCLUDE will cause a router to transition its \214lter)-.2 E
(-)-.2 E(mode for that group to EXCLUDE, a mechanism for transitioning \
a router')72 684 Q 2.5<738c>-.55 G(lter)-2.5 E(-mode back to INCLUDE)-.2
E(must e)72 696 Q 2.5(xist. If)-.15 F
(all systems with a group record in EXCLUDE \214lter)2.5 E
(-mode cease reporting, it is desirable for)-.2 E(the router \214lter)72
708 Q(-mode for that group to transition back to INCLUDE mode. This tra\
nsition occurs when the)-.2 E(group timer e)72 720 Q(xpires and is e)
-.15 E(xplained in detail in section 6.5.)-.15 E(Cain, Deering, Fenner)
72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43
(arajan [P)-.05 F(age 19])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(6.2.2. De\214nition)72 84 R
(of Gr)2.5 E(oup T)-.18 E(imers)-.18 E F0(The group timer is only used \
when a group is in EXCLUDE mode and it represents the time for the *\
\214lter)72 99.6 Q(-)-.2 E(mode* of the group to e)72 111.6 Q
(xpire and switch to INCLUDE mode. W)-.15 E 2.5(ed)-.8 G
(e\214ne a group timer as a decrementing)-2.5 E(timer with a lo)72 123.6
Q(wer bound of zero k)-.25 E(ept per group per attached netw)-.1 E 2.5
(ork. Group)-.1 F(timers are updated according)2.5 E
(to the types of group records recei)72 135.6 Q -.15(ve)-.25 G(d.).15 E
2.5(Ag)72 151.2 S(roup timer e)-2.5 E(xpiring when a router \214lter)
-.15 E(-mode for the group is EXCLUDE means there are no listeners)-.2 E
(on the attached netw)72 163.2 Q(ork in EXCLUDE mode.)-.1 E
(At this point, a router will transition to INCLUDE \214lter)5 E(-)-.2 E
2.5(mode. Section)72 175.2 R(6.5 describes the actions tak)2.5 E
(en when a group timer e)-.1 E(xpires while in EXCLUDE mode.)-.15 E
(The follo)72 190.8 Q(wing table summarizes the role of the group timer)
-.25 E 5(.S)-.55 G(ection 6.4 describes the details of setting the)-5 E
(group timer per type of group record recei)72 202.8 Q -.15(ve)-.25 G
(d.).15 E/F2 10/Courier@0 SF(Group)84 226.8 Q 30(Filter-Mode Group)84
238.8 R(Timer Value)6 E(Actions/Comments)42 E 30
(----------- -----------------)84 250.8 R(----------------)42 E 54
(INCLUDE Timer)84 274.8 R(>= 0)6 E(All members in INCLUDE)84 E(mode.)330
286.8 Q 54(EXCLUDE Timer)84 310.8 R 72 6(>0 A)6 H 6(tl)-6 G
(east one member in)-6 E(EXCLUDE mode.)330 322.8 Q 54(EXCLUDE Timer)84
358.8 R(== 0)6 E(No more listeners to)84 E 6(group. If)330 370.8 R
(all source)6 E(timers have expired then)330 382.8 Q
(delete Group Record.)330 394.8 Q(If there are still)330 406.8 Q
(source record timers)330 418.8 Q(running, switch to)330 430.8 Q
(INCLUDE filter-mode)330 442.8 Q(using those source records)330 454.8 Q
(with running timers as the)330 466.8 Q(INCLUDE source record)330 478.8
Q(state.)330 490.8 Q F1 2.5(6.2.3. De\214nition)72 526.8 R(of Sour)2.5 E
(ce T)-.18 E(imers)-.18 E F0 2.5(As)72 542.4 S(ource timer is k)-2.5 E
(ept per source record and is a decrementing timer with a lo)-.1 E
(wer bound of zero.)-.25 E(Source)5 E
(timers are updated according to the type and \214lter)72 554.4 Q
(-mode of the group record recei)-.2 E -.15(ve)-.25 G 2.5(d. Source).15
F(timers are)2.5 E(al)72 566.4 Q -.1(wa)-.1 G
(ys updated \(for a particular group\) whene).1 E -.15(ve)-.25 G 2.5(rt)
.15 G(he source is present in a recei)-2.5 E -.15(ve)-.25 G 2.5(dr).15 G
(ecord for that group.)-2.5 E(Section 6.4 describes the setting of sour\
ce timers per type of group records recei)72 578.4 Q -.15(ve)-.25 G(d.)
.15 E 2.5(As)72 594 S
(ource record with a running timer with a router \214lter)-2.5 E
(-mode for the group of INCLUDE means that there)-.2 E
(is currently one or more systems \(in INCLUDE \214lter)72 606 Q
(-mode\) which desire to recei)-.2 E .3 -.15(ve t)-.25 H(hat source.).15
E(If a source)5 E(timer e)72 618 Q(xpires with a router \214lter)-.15 E
(-mode for the group of INCLUDE, the router concludes that traf)-.2 E
(\214c from)-.25 E
(this particular source is no longer desired on the attached netw)72 630
Q(ork, and deletes the associated source record.)-.1 E
(Source timers are treated dif)72 645.6 Q
(ferently when a router \214lter)-.25 E(-mode for a group is EXCLUDE.)
-.2 E(If a source record)5 E(has a running timer with a router \214lter)
72 657.6 Q
(-mode for the group of EXCLUDE, it means that at least one system)-.2 E
(desires the source.)72 669.6 Q(It should therefore be forw)5 E
(arded by a router on the netw)-.1 E 2.5(ork. Appendix)-.1 F 2.5(Ad)2.5
G(escribes the)-2.5 E(reasons for k)72 681.6 Q
(eeping state for sources that ha)-.1 E .3 -.15(ve b)-.2 H
(een requested to be forw).15 E(arded while in EXCLUDE state.)-.1 E
(If a source timer e)72 697.2 Q(xpires with a router \214lter)-.15 E
(-mode for the group of EXCLUDE, the router informs the)-.2 E
(routing protocol that there is no longer a recei)72 709.2 Q -.15(ve)
-.25 G 2.5(ro).15 G 2.5(nt)-2.5 G(he netw)-2.5 E(ork interested in traf)
-.1 E(\214c from this source.)-.25 E(Cain, Deering, Fenner)72 768 Q 2.5
(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F
(age 20])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(When a router \214lter)72 84 Q(-mode for a group is \
EXCLUDE, source records are only deleted when the group timer)-.2 E -.15
(ex)72 96 S 2.5(pires. Section).15 F
(6.3 describes the actions that should be tak)2.5 E
(en dependent upon the v)-.1 E(alue of a source timer)-.25 E(.)-.55 E/F1
10/Times-Bold@0 SF 2.5(6.3. IGMPv3)72 132 R(Sour)2.5 E(ce-Speci\214c F)
-.18 E(orwarding Rules)-.25 E F0(When a multicast router recei)72 147.6
Q -.15(ve)-.25 G 2.5(sad).15 G(atagram from a source destined to a part\
icular group, a decision has to)-2.5 E(be made whether to forw)72 159.6
Q(ard the datagram onto an attached netw)-.1 E(ork or not.)-.1 E
(The multicast routing protocol)5 E(in use is in char)72 171.6 Q(ge of \
this decision, and should use the IGMPv3 information to ensure that all)
-.18 E(sources/groups desired on a subnetw)72 183.6 Q(ork are forw)-.1 E
(arded to that subnetw)-.1 E 2.5(ork. IGMPv3)-.1 F(information does not)
2.5 E -.15(ove)72 195.6 S(rride multicast routing information; for e).15
E(xample, if the IGMPv3 \214lter)-.15 E(-mode group for G is EXCLUDE,)
-.2 E 2.5(ar)72 207.6 S(outer may still forw)-2.5 E(ard pack)-.1 E
(ets for e)-.1 E(xcluded sources to a transit subnet.)-.15 E 1.6 -.8
(To s)72 223.2 T(ummarize, the follo).8 E(wing table describes the forw)
-.25 E(arding suggestions made by IGMP to the routing)-.1 E
(protocol for traf)72 235.2 Q
(\214c originating from a source destined to a group.)-.25 E
(It also summarizes the actions tak)5 E(en upon)-.1 E(the e)72 247.2 Q
(xpiration of a source timer based on the router \214lter)-.15 E
(-mode of the group.)-.2 E/F2 10/Courier@0 SF(Group)84 271.2 Q 18
(Filter-Mode Source)84 283.2 R(Timer Value)6 E(Action)24 E 18
(----------- ------------------ ------)84 295.2 R 42(INCLUDE TIMER)84
319.2 R 60 6(>0 S)6 H(uggest to forward traffic)-6 E(from source)306
331.2 Q 42(INCLUDE TIMER)84 355.2 R(== 0)6 E(Suggest to stop forwarding)
72 E(traffic from source and remove)306 367.2 Q(source record.)306 379.2
Q(If there are no)12 E(more source records for the)306 391.2 Q
(group, delete group record.)306 403.2 Q 42(INCLUDE No)84 427.2 R
(Source Elements)6 E(Suggest to not forward source)24 E 42
(EXCLUDE TIMER)84 451.2 R 60 6(>0 S)6 H(uggest to forward traffic from)
-6 E(source)306 463.2 Q 42(EXCLUDE TIMER)84 487.2 R(== 0)6 E
(Suggest to not forward traffic)72 E(from source)306 499.2 Q
(\(DO NOT remove record\))306 511.2 Q 42(EXCLUDE No)84 535.2 R
(Source Elements)6 E(Suggest to forward traffic from)24 E(source)306
547.2 Q F1 2.5(6.4. Action)72 583.2 R(on Reception of Reports)2.5 E 2.5
(6.4.1. Reception)72 607.2 R(of Curr)2.5 E(ent-State Records)-.18 E F0
(When recei)72 622.8 Q(ving Current-State Records, a router updates bot\
h its group and source timers.)-.25 E(In some)5 E(circumstances, the re\
ception of a type of group record will cause the router \214lter)72
634.8 Q(-mode for that group to)-.2 E 2.5(change. The)72 646.8 R
(table belo)2.5 E 2.5(wd)-.25 G(escribes the actions, with respect to s\
tate and timers that occur to a router')-2.5 E 2.5(ss)-.55 G(tate)-2.5 E
(upon reception of Current-State Records.)72 658.8 Q(The follo)72 674.4
Q(wing notation is used to describe the updating of source timers.)-.25
E(The notation \( A, B \) will be used)5 E
(to represent the total number of sources for a particular group, where)
72 686.4 Q(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E
(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 21])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Courier@0 SF 6(A=s)78 84 S
(et of source records whose source timers > 0)-6 E
(\(Sources that at least one host has requested to be forwarded\))102 96
Q 6(B=s)78 108 S(et of source records whose source timers = 0)-6 E
(\(Sources that IGMP will suggest to the routing protocol not to)102 120
Q(forward\))108 132 Q F0(Note that there will only be tw)72 147.6 Q 2.5
(os)-.1 G(ets when a router')-2.5 E 2.5<738c>-.55 G(lter)-2.5 E
(-mode for a group is EXCLUDE.)-.2 E(When a)5 E(router')72 159.6 Q 2.5
<738c>-.55 G(lter)-2.5 E(-mode for a group is INCLUDE, a single set is \
used to describe the set of sources requested to)-.2 E(be forw)72 171.6
Q(arded \(e.g. simply \(A\)\).)-.1 E(In the follo)72 187.2 Q
(wing tables, abbre)-.25 E(viations are used for se)-.25 E -.15(ve)-.25
G(ral v).15 E(ariables \(all of which are described in detail in)-.25 E
(section 8\).)72 199.2 Q(The v)5 E(ariable GMI is an abbre)-.25 E
(viation for the Group Membership Interv)-.25 E
(al, which is the time in)-.25 E(which group memberships will time out.)
72 211.2 Q(The v)5 E(ariable LMQT is an abbre)-.25 E
(viation for the Last Member)-.25 E(Query T)72 223.2 Q(ime, which is th\
e total time spent after Last Member Query Count retransmissions.)-.35 E
(LMQT)5 E(represents the)72 235.2 Q("lea)5 E .3 -.15(ve l)-.2 H(atenc)
.15 E(y", or the dif)-.15 E
(ference between the transmission of a membership change and the)-.25 E
(change in the information gi)72 247.2 Q -.15(ve)-.25 G 2.5(nt).15 G 2.5
(ot)-2.5 G(he routing protocol.)-2.5 E -.4(Wi)72 274.8 S(thin the "Acti\
ons" section of the router state tables, we use the notation \264A=J\
\264, which means that the set).4 E 2.5(Ao)72 286.8 S 2.5(fs)-2.5 G
(ource records should ha)-2.5 E .3 -.15(ve t)-.2 H
(heir source timers set to v).15 E(alue J.)-.25 E('Delete A)5 E 2.5('m)
-1.11 G(eans that the set A of source)-2.5 E(records should be deleted.)
72 298.8 Q('Group T)5 E(imer=J' means that the Group T)-.35 E
(imer for the group should be set to)-.35 E -.25(va)72 310.8 S(lue J.)
.25 E F1(Router State)84 334.8 Q(Report Rec'd)18 E(New Router State)12 E
(Actions)54 E 12(------------ ------------)84 346.8 R 48
(---------------- -------)12 F(INCLUDE \(A\))84 370.8 Q(IS_IN \(B\))24 E
(INCLUDE \(A+B\))30 E(\(B\)=GMI)72 E(INCLUDE \(A\))84 394.8 Q
(IS_EX \(B\))24 E(EXCLUDE \(A*B,B-A\))30 E(\(B-A\)=0)48 E
(Delete \(A-B\))408 406.8 Q(Group Timer=GMI)408 418.8 Q(EXCLUDE \(X,Y\))
84 442.8 Q(IS_IN \(A\))12 E(EXCLUDE \(X+A,Y-A\))30 E(\(A\)=GMI)48 E
(EXCLUDE \(X,Y\))84 466.8 Q(IS_EX \(A\))12 E(EXCLUDE \(A-Y,Y*A\))30 E
(\(A-X-Y\)=GMI)48 E(Delete \(X-A\))408 478.8 Q(Delete \(Y-A\))408 490.8
Q(Group Timer=GMI)408 502.8 Q/F2 10/Times-Bold@0 SF 2.5
(6.4.2. Reception)72 538.8 R(of Filter)2.5 E(-Mode-Change and Sour)-.37
E(ce-List-Change Records)-.18 E F0(When a change in the global state of\
 a group occurs in a system, the system sends either a Source-List-)72
554.4 Q(Change Record or a Filter)72 566.4 Q
(-Mode-Change Record for that group.)-.2 E
(As with Current-State Records, routers)5 E
(must act upon these records and possibly change their o)72 578.4 Q
(wn state to re\215ect the ne)-.25 E 2.5(wd)-.25 G
(esired membership state)-2.5 E(of the netw)72 590.4 Q(ork.)-.1 E
(Routers must query sources that are requested to be no longer forw)72
606 Q(arded to a group.)-.1 E(When a router queries)5 E(or recei)72 618
Q -.15(ve)-.25 G 2.5(saq).15 G
(uery for a speci\214c set of sources, it lo)-2.5 E
(wers its source timers for those sources to a small)-.25 E(interv)72
630 Q(al of Last Member Query T)-.25 E(ime seconds.)-.35 E
(If group records are recei)5 E -.15(ve)-.25 G 2.5(di).15 G 2.5(nr)-2.5
G(esponse to the queries)-2.5 E(which e)72 642 Q
(xpress interest in recei)-.15 E(ving traf)-.25 E
(\214c from the queried sources, the corresponding timers are updated.)
-.25 E(Similarly)72 657.6 Q 2.5(,w)-.65 G
(hen a router queries a speci\214c group, it lo)-2.5 E
(wers its group timer for that group to a small interv)-.25 E(al)-.25 E
(of Last Member Query T)72 669.6 Q(ime seconds.)-.35 E(If an)5 E 2.5(yg)
-.15 G(roup records e)-2.5 E(xpressing EXCLUDE mode interest in the)-.15
E(group are recei)72 681.6 Q -.15(ve)-.25 G 2.5(dw).15 G
(ithin the interv)-2.5 E
(al, the group timer for the group is updated and the suggestion to the)
-.25 E(routing protocol to forw)72 693.6 Q
(ard the group stands without an)-.1 E 2.5(yi)-.15 G(nterruption.)-2.5 E
(During a query period \(i.e. Last Member Query T)72 709.2 Q
(ime seconds\), the IGMP component in the router)-.35 E
(continues to suggest to the routing protocol that it forw)72 721.2 Q
(ards traf)-.1 E(\214c from the groups or sources that it is)-.25 E
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 22])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E 2.5(querying. It)72 84 R
(is not until after Last Member Query T)2.5 E(ime seconds without recei)
-.35 E(ving a record e)-.25 E(xpressing)-.15 E(interest in the queried \
group or sources that the router may prune the group or sources from th\
e netw)72 96 Q(ork.)-.1 E(The follo)72 111.6 Q(wing table describes the\
 changes in group state and the action\(s\) tak)-.25 E(en when recei)-.1
E(ving either)-.25 E(Filter)72 123.6 Q
(-Mode-Change or Source-List-Change Records.)-.2 E
(This table also describes the queries which are sent)5 E
(by the querier when a particular report is recei)72 135.6 Q -.15(ve)
-.25 G(d.).15 E 1.6 -.8(We u)72 151.2 T(se the follo).8 E
(wing notation for describing the queries which are sent.)-.25 E 1.6 -.8
(We u)5 H(se the notation 'Q\(G\)' to).8 E
(describe a Group-Speci\214c Query to G.)72 163.2 Q 1.6 -.8(We u)5 H
(se the notation 'Q\(G,A\)' to describe a Group-and-Source).8 E(Speci\
\214c Query to G with source-list A. If source-list A is null as a resu\
lt of the action \(e.g. A*B\) then no)72 175.2 Q
(query is sent as a result of the operation.)72 187.2 Q
(In order to maintain protocol rob)72 202.8 Q
(ustness, queries sent by actions in the table belo)-.2 E 2.5(wn)-.25 G
(eed to be transmitted)-2.5 E([Last Member Query Count] times, once e)72
214.8 Q -.15(ve)-.25 G(ry [Last Member Query Interv).15 E(al].)-.25 E
(If while scheduling ne)72 230.4 Q 2.5(wq)-.25 G(ueries, there are alre\
ady pending queries to be retransmitted for the same group,)-2.5 E
(the ne)72 242.4 Q 2.5(wa)-.25 G(nd pending queries ha)-2.5 E .3 -.15
(ve t)-.2 H 2.5(ob).15 G 2.5(em)-2.5 G(er)-2.5 E
(ged. In addition, recei)-.18 E -.15(ve)-.25 G 2.5(dh).15 G
(ost reports for a group with pending)-2.5 E(queries may af)72 254.4 Q(\
fect the contents of those queries. Section 6.6.3 describes the process\
 of b)-.25 E(uilding and)-.2 E
(maintaining the state of pending queries.)72 266.4 Q/F1 10/Courier@0 SF
(Router State)84 290.4 Q(Report Rec'd New Router State)18 E(Actions)60 E
12(------------ ------------)84 302.4 R 54(---------------- -------)6 F
(INCLUDE \(A\))84 326.4 Q(ALLOW \(B\))24 E(INCLUDE \(A+B\))24 E
(\(B\)=GMI)78 E(INCLUDE \(A\))84 350.4 Q(BLOCK \(B\))24 E(INCLUDE \(A\))
24 E(Send Q\(G,A*B\))90 E(INCLUDE \(A\))84 374.4 Q(TO_EX \(B\))24 E
(EXCLUDE \(A*B,B-A\))24 E(\(B-A\)=0)54 E(Delete \(A-B\))408 386.4 Q
(Send Q\(G,A*B\))408 398.4 Q(Group Timer=GMI)408 410.4 Q(INCLUDE \(A\))
84 434.4 Q(TO_IN \(B\))24 E(INCLUDE \(A+B\))24 E(\(B\)=GMI)78 E
(Send Q\(G,A-B\))408 446.4 Q(EXCLUDE \(X,Y\))84 470.4 Q(ALLOW \(A\))12 E
(EXCLUDE \(X+A,Y-A\))24 E(\(A\)=GMI)54 E(EXCLUDE \(X,Y\))84 494.4 Q
(BLOCK \(A\))12 E(EXCLUDE \(X+\(A-Y\),Y\))24 E(\(A-X-Y\)=Group)42 E
(Timer)72 506.4 Q(Send Q\(G,A-Y\))408 518.4 Q(EXCLUDE \(X,Y\))84 542.4 Q
(TO_EX \(A\))12 E(EXCLUDE \(A-Y,Y*A\))24 E(\(A-X-Y\)=Group)54 E(Timer)72
554.4 Q(Delete \(X-A\))408 566.4 Q(Delete \(Y-A\))408 578.4 Q
(Send Q\(G,A-Y\))408 590.4 Q(Group Timer=GMI)408 602.4 Q
(EXCLUDE \(X,Y\))84 626.4 Q(TO_IN \(A\))12 E(EXCLUDE \(X+A,Y-A\))24 E
(\(A\)=GMI)54 E(Send Q\(G,X-A\))408 638.4 Q(Send Q\(G\))408 650.4 Q/F2
10/Times-Bold@0 SF 2.5(6.5. Switching)72 686.4 R(Router Filter)2.5 E
(-Modes)-.37 E F0(The group timer is used as a mechanism for transition\
ing the router \214lter)72 702 Q(-mode from EXCLUDE to)-.2 E(INCLUDE.)72
714 Q(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)
-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 23])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(When a group timer e)72 84 Q
(xpires with a router \214lter)-.15 E
(-mode of EXCLUDE, a router assumes that there are no)-.2 E
(systems with a *\214lter)72 96 Q
(-mode* of EXCLUDE present on the attached netw)-.2 E 2.5(ork. When)-.1
F 2.5(ar)2.5 G(outer')-2.5 E 2.5<738c>-.55 G(lter)-2.5 E(-mode)-.2 E
(for a group is EXCLUDE and the group timer e)72 108 Q
(xpires, the router \214lter)-.15 E(-mode for the group transitions to)
-.2 E(INCLUDE.)72 120 Q 2.5(Ar)72 135.6 S(outer uses source records wit\
h running source timers as its state for the switch to a \214lter)-2.5 E
(-mode of)-.2 E 2.5(INCLUDE. If)72 147.6 R(there are an)2.5 E 2.5(ys)
-.15 G(ource records with source timers greater than zero \(i.e. reques\
ted to be)-2.5 E(forw)72 159.6 Q(arded\), a router switches to \214lter)
-.1 E(-mode of INCLUDE using those source records.)-.2 E(Source records)
5 E(whose timers are zero \(from the pre)72 171.6 Q
(vious EXCLUDE mode\) are deleted.)-.25 E -.15(Fo)72 187.2 S 2.5(re).15
G(xample, if a router')-2.65 E 2.5(ss)-.55 G
(tate for a group is EXCLUDE\(X,Y\) and the group timer e)-2.5 E
(xpires for that group,)-.15 E(the router switches to \214lter)72 199.2
Q(-mode of INCLUDE with state INCLUDE\(X\).)-.2 E/F1 10/Times-Bold@0 SF
2.5(6.6. Action)72 235.2 R(on Reception of Queries)2.5 E 2.5(6.6.1. T)72
259.2 R(imer Updates)-.18 E F0(When a router sends or recei)72 274.8 Q
-.15(ve)-.25 G 2.5(saq).15 G(uery with a clear Suppress Router)-2.5 E
(-Side Processing \215ag, it must update)-.2 E
(its timers to re\215ect the correct timeout v)72 286.8 Q
(alues for the group or sources being queried.)-.25 E(The follo)5 E
(wing table)-.25 E(describes the timer actions when sending or recei)72
298.8 Q(ving a Group-Speci\214c or Group-and-Source Speci\214c)-.25 E
(Query with the Suppress Router)72 310.8 Q
(-Side Processing \215ag not set.)-.2 E/F2 10/Courier@0 SF 30
(Query Action)96 334.8 R 30(----- ------)96 346.8 R 24(Q\(G,A\) Source)
96 358.8 R(Timer for sources in A are lowered to LMQT)6 E 36
(Q\(G\) Group)96 370.8 R(Timer is lowered to LMQT)6 E F0
(When a router sends or recei)72 386.4 Q -.15(ve)-.25 G 2.5(saq).15 G
(uery with the Suppress Router)-2.5 E
(-Side Processing \215ag set, it will not)-.2 E(update its timers.)72
398.4 Q F1 2.5(6.6.2. Querier)72 434.4 R(Election)2.5 E F0(IGMPv3 elect\
s a single querier per subnet using the same querier election mechanism\
 as IGMPv2, namely)72 450 Q(by IP address.)72 462 Q(When a router recei)
5 E -.15(ve)-.25 G 2.5(saq).15 G(uery with a lo)-2.5 E
(wer IP address, it sets the Other)-.25 E(-Querier)-.2 E(-Present)-.2 E
(timer to Other Querier Present Interv)72 474 Q
(al and ceases to send queries on the netw)-.25 E(ork if it w)-.1 E
(as the pre)-.1 E(viously)-.25 E(elected querier)72 486 Q 5(.A)-.55 G
(fter its Other)-5 E(-Querier Present timer e)-.2 E
(xpires, it should be)-.15 E(gin sending General Queries.)-.15 E
(If a router recei)72 501.6 Q -.15(ve)-.25 G 2.5(sa).15 G 2.5(no)-2.5 G
(lder v)-2.5 E(ersion query)-.15 E 2.5(,i)-.65 G 2.5(tM)-2.5 G
(UST use the oldest v)-2.5 E(ersion of IGMP on the netw)-.15 E 2.5
(ork. F)-.1 F(or a)-.15 E
(detailed description of compatibility issues between IGMP v)72 513.6 Q
(ersions see section 7.)-.15 E F1 2.5(6.6.3. Building)72 549.6 R
(and Sending Speci\214c Queries)2.5 E 2.5(6.6.3.1. Building)72 573.6 R
(and Sending Gr)2.5 E(oup Speci\214c Queries)-.18 E F0
(When a table action "Send Q\(G\)" is encountered, then the group timer)
72 589.2 Q(must be lo)72 601.2 Q(wered to LMQT)-.25 E 2.5(.T)-.74 G(he \
router must then immediately send a group speci\214c query as well as)
-2.5 E(schedule [Last Member Query Count - 1] query retransmissions to \
be sent e)72 613.2 Q -.15(ve)-.25 G(ry [Last Member Query).15 E(Interv)
72 625.2 Q(al] o)-.25 E -.15(ve)-.15 G 2.5(r[).15 G(Last Member Query T)
-2.5 E(ime].)-.35 E(When transmitting a group speci\214c query)72 640.8
Q 2.5(,i)-.65 G 2.5(ft)-2.5 G(he group timer is lar)-2.5 E
(ger than LMQT)-.18 E 2.5(,t)-.74 G(he "Suppress Router)-2.5 E(-)-.2 E
(Side Processing" bit is set in the query message.)72 652.8 Q
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 24])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(6.6.3.2. Building)72 84 R
(and Sending Gr)2.5 E(oup and Sour)-.18 E(ce Speci\214c Queries)-.18 E
F0(When a table action "Send Q\(G,X\)" is encountered by a querier in t\
he table in section 6.4.2, the follo)72 99.6 Q(wing)-.25 E(actions must\
 be performed for each of the sources in X of group G, with source time\
r lar)72 111.6 Q(ger than LMQT)-.18 E(:)-.5 E 5(oS)72 127.2 S(et number\
 of retransmissions for each source to [Last Member Query Count].)-5 E 5
(oL)72 142.8 S -.25(ow)-5 G(er source timer to LMQT).25 E(.)-.74 E(The \
router must then immediately send a group and source speci\214c query a\
s well as schedule [Last Member)72 158.4 Q
(Query Count - 1] query retransmissions to be sent e)72 170.4 Q -.15(ve)
-.25 G(ry [Last Member Query Interv).15 E(al] o)-.25 E -.15(ve)-.15 G
2.5(r[).15 G(Last Member)-2.5 E(Query T)72 182.4 Q 2.5(ime]. The)-.35 F
(contents of these queries are calculated as follo)2.5 E(ws.)-.25 E
(When b)72 198 Q
(uilding a group and source speci\214c query for a group G, tw)-.2 E 2.5
(os)-.1 G(eparate query messages are sent for)-2.5 E
(the group. The \214rst one has the "Suppress Router)72 210 Q
(-Side Processing" bit set and contains all the sources with)-.2 E
(retransmission state and timers greater than LMQT)72 222 Q 2.5(.T)-.74
G(he second has the "Suppress Router)-2.5 E(-Side Processing")-.2 E(bit\
 clear and contains all the sources with retransmission state and timer\
s lo)72 234 Q(wer or equal to LMQT)-.25 E 2.5(.I)-.74 G 2.5(fe)-2.5 G
(ither)-2.5 E(of the tw)72 246 Q 2.5(oc)-.1 G
(alculated messages does not contain an)-2.5 E 2.5(ys)-.15 G
(ources, then its transmission is suppressed.)-2.5 E(Note: If a group s\
peci\214c query is scheduled to be transmitted at the same time as a gr\
oup and source)72 261.6 Q(speci\214c query for the same group, then tra\
nsmission of the group and source speci\214c message with the)72 273.6 Q
("Suppress Router)72 285.6 Q
(-Side Processing" bit set may be suppressed.)-.2 E F1 2.5(7. INTER)72
321.6 R(OPERA)-.3 E(TION WITH OLDER VERSIONS OF IGMP)-.95 E F0(IGMP v)72
337.2 Q
(ersion 3 hosts and routers interoperate with hosts and routers that ha)
-.15 E .3 -.15(ve n)-.2 H(ot yet been upgraded to).15 E 2.5
(IGMPv3. This)72 349.2 R(compatibility is maintained by hosts and route\
rs taking appropriate actions depending on)2.5 E(the v)72 361.2 Q
(ersions of IGMP operating on hosts and routers within a netw)-.15 E
(ork.)-.1 E F1 2.5(7.1. Query)72 397.2 R -1(Ve)2.5 G(rsion Distinctions)
1 E F0(The IGMP v)72 412.8 Q
(ersion of a Membership Query message is determined as follo)-.15 E(ws:)
-.25 E/F2 10/Courier@0 SF
(IGMPv1 Query: length = 8 octets AND Max Resp Code field is zero)90
436.8 Q(IGMPv2 Query: length = 8 octets AND Max Resp Code field is)90
460.8 Q(non-zero)174 472.8 Q(IGMPv3 Query: length >= 12 octets)90 496.8
Q F0(Query messages that do not match an)72 512.4 Q 2.5(yo)-.15 G 2.5
(ft)-2.5 G(he abo)-2.5 E .3 -.15(ve c)-.15 H
(onditions \(e.g., a Query of length 10 octets\) MUST be).15 E
(silently ignored.)72 524.4 Q F1 2.5(7.2. Gr)72 560.4 R(oup Member Beha)
-.18 E(vior)-.25 E 2.5(7.2.1. In)72 584.4 R(the Pr)2.5 E
(esence of Older V)-.18 E(ersion Queriers)-1 E F0
(In order to be compatible with older v)72 600 Q
(ersion routers, IGMPv3 hosts MUST operate in v)-.15 E(ersion 1 and v)
-.15 E(ersion)-.15 E 2.5(2c)72 612 S(ompatibility modes.)-2.5 E
(IGMPv3 hosts MUST k)5 E(eep state per local interf)-.1 E(ace re)-.1 E
-.05(ga)-.15 G(rding the compatibility).05 E(mode of each attached netw)
72 624 Q 2.5(ork. A)-.1 F(host')2.5 E 2.5(sc)-.55 G
(ompatibility mode is determined from the Host Compatibility)-2.5 E
(Mode v)72 636 Q
(ariable which can be in one of three states: IGMPv1, IGMPv2 or IGMPv3.)
-.25 E(This v)7.5 E(ariable is k)-.25 E(ept)-.1 E(per interf)72 648 Q
(ace and is dependent on the v)-.1 E
(ersion of General Queries heard on that interf)-.15 E
(ace as well as the Older)-.1 E -1.11(Ve)72 660 S
(rsion Querier Present timers for the interf)1.11 E(ace.)-.1 E
(In order to switch gracefully between v)72 675.6 Q(ersions of IGMP)-.15
E 2.5(,h)-1.11 G(osts k)-2.5 E(eep both an IGMPv1 Querier Present timer)
-.1 E(and an IGMPv2 Querier Present timer per interf)72 687.6 Q 2.5
(ace. IGMPv1)-.1 F(Querier Present is set to Older V)2.5 E(ersion)-1.11
E(Querier Present T)72 699.6 Q(imeout seconds whene)-.35 E -.15(ve)-.25
G 2.5(ra).15 G 2.5(nI)-2.5 G(GMPv1 Membership Query is recei)-2.5 E -.15
(ve)-.25 G 2.5(d. IGMPv2).15 F(Querier)2.5 E(Present is set to Older V)
72 711.6 Q(ersion Querier Present T)-1.11 E(imeout seconds whene)-.35 E
-.15(ve)-.25 G 2.5(ra).15 G 2.5(nI)-2.5 G(GMPv2 General Query is)-2.5 E
(recei)72 723.6 Q -.15(ve)-.25 G(d.).15 E(Cain, Deering, Fenner)72 768 Q
2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)
-.05 F(age 25])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(The Host Compatibility Mode of an interf)72 84 Q
(ace changes whene)-.1 E -.15(ve)-.25 G 2.5(ra).15 G 2.5(no)-2.5 G
(lder v)-2.5 E(ersion query \(than the current)-.15 E
(compatibility mode\) is heard or when certain timer conditions occur)72
96 Q 5(.W)-.55 G(hen the IGMPv1 Querier Present)-5 E(timer e)72 108 Q(x\
pires, a host switches to Host Compatibility mode of IGMPv2 if it has a\
 running IGMPv2 Querier)-.15 E(Present timer)72 120 Q 5(.I)-.55 G 2.5
(fi)-5 G 2.5(td)-2.5 G(oes not ha)-2.5 E .3 -.15(ve a r)-.2 H
(unning IGMPv2 Querier Present timer then it switches to Host).15 E
(Compatibility of IGMPv3.)72 132 Q
(When the IGMPv2 Querier Present timer e)5 E
(xpires, a host switches to Host)-.15 E(Compatibility mode of IGMPv3.)72
144 Q(The Host Compatibility Mode v)72 159.6 Q
(ariable is based on whether an older v)-.25 E(ersion General query w)
-.15 E(as heard in the)-.1 E(last Older V)72 171.6 Q
(ersion Querier Present T)-1.11 E(imeout seconds.)-.35 E
(The Host Compatibility Mode is set depending on the)5 E(follo)72 183.6
Q(wing:)-.25 E/F1 10/Courier@0 SF(Host Compatibility Mode)96 207.6 Q
(Timer State)42 E 36(----------------------- -----------)96 219.6 R
(IGMPv3 \(default\))132 243.6 Q(IGMPv2 Querier Present not running)48 E
(and IGMPv1 Querier Present not running)276 255.6 Q 102(IGMPv2 IGMPv2)
132 279.6 R(Querier Present running)6 E
(and IGMPv1 Querier Present not running)276 291.6 Q 102(IGMPv1 IGMPv1)
132 315.6 R(Querier Present running)6 E F0(If a host recei)72 331.2 Q
-.15(ve)-.25 G 2.5(saq).15 G(uery which causes its Querier Present time\
rs to be updated and correspondingly its)-2.5 E
(compatibility mode, it should switch compatibility modes immediately)72
343.2 Q(.)-.65 E(When Host Compatibility Mode is IGMPv3, a host acts us\
ing the IGMPv3 protocol on that interf)72 358.8 Q(ace.)-.1 E(When Host \
Compatibility Mode is IGMPv2, a host acts in IGMPv2 compatibility mode,\
 using only the)72 370.8 Q(IGMPv2 protocol, on that interf)72 382.8 Q
2.5(ace. When)-.1 F
(Host Compatibility Mode is IGMPv1, a host acts in IGMPv1)2.5 E
(compatibility mode, using only the IGMPv1 protocol on that interf)72
394.8 Q(ace.)-.1 E(An IGMPv1 router will send General Queries with the \
Max Resp Code set to 0.)72 410.4 Q(This MUST be interpreted)5 E(as a v)
72 422.4 Q(alue of 100 \(10 seconds\).)-.25 E(An IGMPv2 router will sen\
d General Queries with the Max Resp Code set to the desired Max Resp T)
72 438 Q(ime,)-.35 E
(i.e. the full range of this \214eld is linear and the e)72 450 Q
(xponential algorithm described in section 4.1.1 is not used.)-.15 E
(Whene)72 465.6 Q -.15(ve)-.25 G 2.5(rah).15 G(ost changes its compatib\
ility mode, it cancels all its pending response and retransmission)-2.5
E(timers.)72 477.6 Q/F2 10/Times-Bold@0 SF 2.5(7.2.2. In)72 513.6 R
(the Pr)2.5 E(esence of Older V)-.18 E(ersion Gr)-1 E(oup Members)-.18 E
F0(An IGMPv3 host may be placed on a netw)72 529.2 Q
(ork where there are hosts that ha)-.1 E .3 -.15(ve n)-.2 H
(ot yet been upgraded to).15 E 2.5(IGMPv3. A)72 541.2 R(host MA)2.5 E
2.5(Ya)-1.05 G(llo)-2.5 E 2.5(wi)-.25 G
(ts IGMPv3 Membership Record to be suppressed by either a V)-2.5 E
(ersion 1)-1.11 E(Membership Report, or a V)72 553.2 Q
(ersion 2 Membership Report.)-1.11 E F2 2.5(7.3. Multicast)72 589.2 R
(Router Beha)2.5 E(vior)-.25 E 2.5(7.3.1. In)72 613.2 R(the Pr)2.5 E
(esence of Older V)-.18 E(ersion Queriers)-1 E F0
(IGMPv3 routers may be placed on a netw)72 628.8 Q
(ork where at least one router on the netw)-.1 E(ork has not yet been)
-.1 E(upgraded to IGMPv3.)72 640.8 Q(The follo)5 E
(wing requirements apply:)-.25 E 5(oI)72 656.4 S 2.5(fa)-5 G .3 -.15
(ny o)-2.5 H(lder v).15 E
(ersions of IGMP are present on routers, the querier MUST use the lo)
-.15 E(west v)-.25 E(ersion of IGMP)-.15 E(present on the netw)82 668.4
Q 2.5(ork. This)-.1 F(must be administrati)2.5 E -.15(ve)-.25 G
(ly assured; routers that desire to be compatible with).15 E
(IGMPv1 and IGMPv2 MUST ha)82 680.4 Q .3 -.15(ve a c)-.2 H
(on\214guration option to act in IGMPv1 or IGMPv2 compatibility).15 E
2.5(modes. When)82 692.4 R(in IGMPv1 mode, routers MUST send Periodic Q\
ueries with a Max Resp Code of 0 and)2.5 E(truncated at the Group Addre\
ss \214eld \(i.e. 8 bytes long\), and MUST ignore Lea)82 704.4 Q .3 -.15
(ve G)-.2 H(roup messages.).15 E(The)5 E(y)-.15 E(SHOULD also w)82 716.4
Q(arn about recei)-.1 E(ving an IGMPv2 or IGMPv3 query)-.25 E 2.5(,a)
-.65 G(lthough such w)-2.5 E(arnings MUST be)-.1 E
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 26])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E 2.5(rate-limited. When)82 84 R(in IGMPv2 mode, route\
rs MUST send Periodic Queries truncated at the Group)2.5 E
(Address \214eld \(i.e. 8 bytes long\), and SHOULD also w)82 96 Q
(arn about recei)-.1 E(ving an IGMPv3 query \(such)-.25 E -.1(wa)82 108
S(rnings MUST be rate-limited\).).1 E(The)5 E 2.5(ya)-.15 G
(lso MUST \214ll in the Max Resp T)-2.5 E(ime in the Max Resp Code)-.35
E(\214eld, i.e. the e)82 120 Q
(xponential algorithm described in section 4.1.1 is not used.)-.15 E 5
(oI)72 135.6 S 2.5(far)-5 G(outer is not e)-2.5 E(xplicitly con\214gure\
d to use IGMPv1 or IGMPv2 and hears an IGMPv1 Query or)-.15 E
(IGMPv2 General Query)82 147.6 Q 2.5(,i)-.65 G 2.5(tS)-2.5 G
(HOULD log a w)-2.5 E 2.5(arning. These)-.1 F -.1(wa)2.5 G
(rnings MUST be rate-limited.).1 E/F1 10/Times-Bold@0 SF 2.5(7.3.2. In)
72 183.6 R(the Pr)2.5 E(esence of Older V)-.18 E(ersion Gr)-1 E
(oup Members)-.18 E F0(IGMPv3 routers may be placed on a netw)72 199.2 Q
(ork where there are hosts that ha)-.1 E .3 -.15(ve n)-.2 H
(ot yet been upgraded to).15 E 2.5(IGMPv3. In)72 211.2 R
(order to be compatible with older v)2.5 E
(ersion hosts, IGMPv3 routers MUST operate in v)-.15 E(ersion 1)-.15 E
(and v)72 223.2 Q(ersion 2 compatibility modes.)-.15 E(IGMPv3 routers k)
5 E(eep a compatibility mode per group record.)-.1 E(A)5 E(group')72
235.2 Q 2.5(sc)-.55 G
(ompatibility mode is determined from the Group Compatibility Mode v)
-2.5 E(ariable which can be in)-.25 E
(one of three states: IGMPv1, IGMPv2 or IGMPv3.)72 247.2 Q(This v)7.5 E
(ariable is k)-.25 E(ept per group record and is dependent)-.1 E
(on the v)72 259.2 Q(ersion of Membership Reports heard for that group \
as well as the Older V)-.15 E(ersion Host Present timer)-1.11 E
(for the group.)72 271.2 Q(In order to switch gracefully between v)72
286.8 Q(ersions of IGMP)-.15 E 2.5(,r)-1.11 G(outers k)-2.5 E
(eep an IGMPv1 Host Present timer and an)-.1 E(IGMPv2 Host Present time\
r per group record. The IGMPv1 Host Present timer is set to Older V)72
298.8 Q(ersion Host)-1.11 E(Present T)72 310.8 Q(imeout seconds whene)
-.35 E -.15(ve)-.25 G 2.5(ra).15 G 2.5(nI)-2.5 G
(GMPv1 Membership Report is recei)-2.5 E -.15(ve)-.25 G
(d. The IGMPv2 Host Present).15 E(timer is set to Older V)72 322.8 Q
(ersion Host Present T)-1.11 E(imeout seconds whene)-.35 E -.15(ve)-.25
G 2.5(ra).15 G 2.5(nI)-2.5 G(GMPv2 Membership Report is)-2.5 E(recei)72
334.8 Q -.15(ve)-.25 G(d.).15 E
(The Group Compatibility Mode of a group record changes whene)72 350.4 Q
-.15(ve)-.25 G 2.5(ra).15 G 2.5(no)-2.5 G(lder v)-2.5 E
(ersion report \(than the)-.15 E(current compatibility mode\) is heard \
or when certain timer conditions occur)72 362.4 Q 5(.W)-.55 G
(hen the IGMPv1 Host)-5 E(Present timer e)72 374.4 Q(xpires, a router s\
witches to Group Compatibility mode of IGMPv2 if it has a running)-.15 E
(IGMPv2 Host Present timer)72 386.4 Q 5(.I)-.55 G 2.5(fi)-5 G 2.5(td)
-2.5 G(oes not ha)-2.5 E .3 -.15(ve a r)-.2 H
(unning IGMPv2 Host Present timer then it switches to).15 E
(Group Compatibility of IGMPv3.)72 398.4 Q
(When the IGMPv2 Host Present timer e)5 E(xpires and the IGMPv1 Host)
-.15 E(Present timer is not running, a router switches to Group Compati\
bility mode of IGMPv3.)72 410.4 Q(Note that when a)5 E
(group switches back to IGMPv3 mode, it tak)72 422.4 Q
(es some time to re)-.1 E -.05(ga)-.15 G
(in source-speci\214c state information.).05 E
(Source-speci\214c information will be learned during the ne)72 434.4 Q
(xt General Query)-.15 E 2.5(,b)-.65 G(ut sources that should be)-2.7 E
(block)72 446.4 Q(ed will not be block)-.1 E
(ed until [Group Membership Interv)-.1 E(al] after that.)-.25 E
(The Group Compatibility Mode v)72 462 Q
(ariable is based on whether an older v)-.25 E(ersion report w)-.15 E
(as heard in the last)-.1 E(Older V)72 474 Q(ersion Host Present T)-1.11
E(imeout seconds.)-.35 E
(The Group Compatibility Mode is set depending on the)5 E(follo)72 486 Q
(wing:)-.25 E/F2 10/Courier@0 SF(Group Compatibility Mode)96 510 Q
(Timer State)36 E 30(------------------------ -----------)96 522 R
(IGMPv3 \(default\))132 546 Q(IGMPv2 Host Present not running)48 E
(and IGMPv1 Host Present not running)276 558 Q 102(IGMPv2 IGMPv2)132 582
R(Host Present running)6 E(and IGMPv1 Host Present not running)276 594 Q
102(IGMPv1 IGMPv1)132 618 R(Host Present running)6 E F0
(If a router recei)72 633.6 Q -.15(ve)-.25 G 2.5(sar).15 G(eport which \
causes its older Host Present timers to be updated and correspondingly)
-2.5 E(its compatibility mode, it SHOULD switch compatibility modes imm\
ediately)72 645.6 Q(.)-.65 E(When Group Compatibility Mode is IGMPv3, a\
 router acts using the IGMPv3 protocol for that group.)72 661.2 Q
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 27])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(When Group Compatibility Mode is IGMPv2, a router in\
ternally translates the follo)72 84 Q(wing IGMPv2)-.25 E
(messages for that group to their IGMPv3 equi)72 96 Q -.25(va)-.25 G
(lents:).25 E/F1 10/Courier@0 SF(IGMPv2 Message)96 120 Q
(IGMPv3 Equivalent)96 E 90(-------------- -----------------)96 132 R 138
(Report IS_EX\()108 156 R({} \))6 E 144(Leave TO_IN\()108 180 R({} \))6
E F0(IGMPv3 BLOCK messages are ignored, as are source-lists in T)72 204
Q(O_EX\(\) messages \(i.e. an)-.18 E 2.5(yT)-.15 G(O_EX\(\))-2.68 E
(message is treated as T)72 216 Q(O_EX\( {} \)\).)-.18 E(When Group Com\
patibility Mode is IGMPv1, a router internally translates the follo)72
231.6 Q(wing IGMPv1 and)-.25 E
(IGMPv2 messages for that group to their IGMPv3 equi)72 243.6 Q -.25(va)
-.25 G(lents:).25 E F1(IGMP Message)96 267.6 Q(IGMPv3 Equivalent)108 E
102(------------ -----------------)96 279.6 R(v1 Report)108 303.6 Q
(IS_EX\( {} \))132 E(v2 Report)108 327.6 Q(IS_EX\( {} \))132 E F0
(In addition to ignoring IGMPv3 BLOCK messages and source-lists in T)72
351.6 Q(O_EX\(\) messages as in IGMPv2)-.18 E
(Group Compatibility Mode, IGMPv2 Lea)72 363.6 Q .3 -.15(ve m)-.2 H
(essages and IGMPv3 T).15 E(O_IN\(\) messages are also ignored.)-.18 E
/F2 10/Times-Bold@0 SF 2.5(8. LIST)72 399.6 R
(OF TIMERS, COUNTERS, AND THEIR DEF)2.5 E -.5(AU)-.9 G 1.84 -.92(LT V).5
H(ALUES)-.43 E F0(Most of these timers are con\214gurable.)72 415.2 Q
(If non-def)5 E(ault settings are used, the)-.1 E 2.5(yM)-.15 G
(UST be consistent among all)-2.5 E
(systems on a single link. Note that parentheses are used to group e)72
427.2 Q(xpressions to mak)-.15 E 2.5(et)-.1 G(he algebra clear)-2.5 E(.)
-.55 E F2 2.5(8.1. Rob)72 463.2 R(ustness V)-.2 E(ariable)-.92 E F0
(The Rob)72 478.8 Q(ustness V)-.2 E(ariable allo)-1.11 E
(ws tuning for the e)-.25 E(xpected pack)-.15 E(et loss on a netw)-.1 E
2.5(ork. If)-.1 F 2.5(an)2.5 G(etw)-2.5 E(ork is e)-.1 E(xpected)-.15 E
(to be lossy)72 490.8 Q 2.5(,t)-.65 G(he Rob)-2.5 E(ustness V)-.2 E
(ariable may be increased.)-1.11 E(IGMP is rob)5 E(ust to \(Rob)-.2 E
(ustness V)-.2 E(ariable - 1\) pack)-1.11 E(et)-.1 E 2.5(losses. The)72
502.8 R(Rob)2.5 E(ustness V)-.2 E(ariable MUST NO)-1.11 E 2.5(Tb)-.4 G
2.5(ez)-2.5 G(ero, and SHOULD NO)-2.5 E 2.5(Tb)-.4 G 2.5(eo)-2.5 G 2.5
(ne. Def)-2.5 F(ault: 2)-.1 E F2 2.5(8.2. Query)72 538.8 R(Inter)2.5 E
-.1(va)-.1 G(l).1 E F0(The Query Interv)72 554.4 Q(al is the interv)-.25
E(al between General Queries sent by the Querier)-.25 E 5(.D)-.55 G(ef)
-5 E(ault: 125 seconds.)-.1 E(By v)72 570 Q(arying the [Query Interv)
-.25 E
(al], an administrator may tune the number of IGMP messages on the netw)
-.25 E(ork;)-.1 E(lar)72 582 Q(ger v)-.18 E
(alues cause IGMP Queries to be sent less often.)-.25 E F2 2.5
(8.3. Query)72 618 R(Response Inter)2.5 E -.1(va)-.1 G(l).1 E F0
(The Max Response T)72 633.6 Q(ime used to calculate the Max Resp Code \
inserted into the periodic General Queries.)-.35 E(Def)72 645.6 Q
(ault: 100 \(10 seconds\))-.1 E(By v)72 661.2 Q
(arying the [Query Response Interv)-.25 E
(al], an administrator may tune the b)-.25 E
(urstiness of IGMP messages on)-.2 E(the netw)72 673.2 Q(ork; lar)-.1 E
(ger v)-.18 E(alues mak)-.25 E 2.5(et)-.1 G(he traf)-2.5 E(\214c less b)
-.25 E(ursty)-.2 E 2.5(,a)-.65 G 2.5(sh)-2.5 G
(ost responses are spread out o)-2.5 E -.15(ve)-.15 G 2.5(ral).15 G(ar)
-2.5 E(ger)-.18 E(interv)72 685.2 Q 2.5(al. The)-.25 F
(number of seconds represented by the [Query Response Interv)2.5 E
(al] must be less than the)-.25 E([Query Interv)72 697.2 Q(al].)-.25 E
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 28])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(8.4. Gr)72 84 R
(oup Membership Inter)-.18 E -.1(va)-.1 G(l).1 E F0
(The Group Membership Interv)72 99.6 Q(al is the amount of time that mu\
st pass before a multicast router decides)-.25 E
(there are no more members of a group or a particular source on a netw)
72 111.6 Q(ork.)-.1 E(This v)72 127.2 Q(alue MUST be \(\(the Rob)-.25 E
(ustness V)-.2 E(ariable\) times \(the Query Interv)-1.11 E
(al\)\) plus \(one Query Response)-.25 E(Interv)72 139.2 Q(al\).)-.25 E
F1 2.5(8.5. Other)72 175.2 R(Querier Pr)2.5 E(esent Inter)-.18 E -.1(va)
-.1 G(l).1 E F0(The Other Querier Present Interv)72 190.8 Q(al is the l\
ength of time that must pass before a multicast router decides that)-.25
E(there is no longer another multicast router which should be the queri\
er)72 202.8 Q 5(.T)-.55 G(his v)-5 E(alue MUST be \(\(the)-.25 E(Rob)72
214.8 Q(ustness V)-.2 E(ariable\) times \(the Query Interv)-1.11 E
(al\)\) plus \(one half of one Query Response Interv)-.25 E(al\).)-.25 E
F1 2.5(8.6. Startup)72 250.8 R(Query Inter)2.5 E -.1(va)-.1 G(l).1 E F0
(The Startup Query Interv)72 266.4 Q(al is the interv)-.25 E
(al between General Queries sent by a Querier on startup.)-.25 E(Def)5 E
(ault:)-.1 E(1/4 the Query Interv)72 278.4 Q(al.)-.25 E F1 2.5
(8.7. Startup)72 314.4 R(Query Count)2.5 E F0(The Startup Query Count i\
s the number of Queries sent out on startup, separated by the Startup Q\
uery)72 330 Q(Interv)72 342 Q 2.5(al. Def)-.25 F(ault: the Rob)-.1 E
(ustness V)-.2 E(ariable.)-1.11 E F1 2.5(8.8. Last)72 378 R
(Member Query Inter)2.5 E -.1(va)-.1 G(l).1 E F0
(The Last Member Query Interv)72 393.6 Q(al is the Max Response T)-.25 E
(ime used to calculate the Max Resp Code inserted)-.35 E
(into Group-Speci\214c Queries sent in response to Lea)72 405.6 Q .3
-.15(ve G)-.2 H(roup messages.).15 E(It is also the Max Response T)5 E
(ime)-.35 E(used in calculating the Max Resp Code for Group-and-Source-\
Speci\214c Query messages.)72 417.6 Q(Def)5 E(ault: 10 \(1)-.1 E
(second\))72 429.6 Q(Note that for v)72 445.2 Q
(alues of LMQI greater than 12.8 seconds, a limited set of v)-.25 E
(alues can be represented,)-.25 E(corresponding to sequential v)72 457.2
Q(alues of Max Resp Code.)-.25 E(When con)5 E -.15(ve)-.4 G
(rting a con\214gured time to a Max Resp).15 E(Code v)72 469.2 Q
(alue, it is recommended to use the e)-.25 E(xact v)-.15 E
(alue if possible, or the ne)-.25 E(xt lo)-.15 E(wer v)-.25 E
(alue if the requested)-.25 E -.25(va)72 481.2 S(lue is not e).25 E
(xactly representable.)-.15 E(This v)72 496.8 Q
(alue may be tuned to modify the "lea)-.25 E .3 -.15(ve l)-.2 H(atenc)
.15 E(y" of the netw)-.15 E 2.5(ork. A)-.1 F(reduced v)2.5 E
(alue results in reduced)-.25 E
(time to detect the loss of the last member of a group or source.)72
508.8 Q F1 2.5(8.9. Last)72 544.8 R(Member Query Count)2.5 E F0(The Las\
t Member Query Count is the number of Group-Speci\214c Queries sent bef\
ore the router assumes)72 560.4 Q(there are no local members.)72 572.4 Q
(The Last Member Query Count is also the number of Group-and-Source-)5 E
(Speci\214c Queries sent before the router assumes there are no listene\
rs for a particular source.)72 584.4 Q(Def)5 E(ault: the)-.1 E(Rob)72
596.4 Q(ustness V)-.2 E(ariable.)-1.11 E F1 2.5(8.10. Last)72 632.4 R
(Member Query T)2.5 E(ime)-.18 E F0(The Last Member Query T)72 648 Q
(ime is the time v)-.35 E
(alue represented by the Last Member Query Interv)-.25 E(al, multiplied)
-.25 E(by the Last Member Query Count.)72 660 Q(It is not a tunable v)5
E(alue, b)-.25 E(ut may be tuned by changing its components.)-.2 E F1
2.5(8.11. Unsolicited)72 696 R(Report Inter)2.5 E -.1(va)-.1 G(l).1 E F0
(The Unsolicited Report Interv)72 711.6 Q
(al is the time between repetitions of a host')-.25 E 2.5(si)-.55 G
(nitial report of membership in a)-2.5 E 2.5(group. Def)72 723.6 R
(ault: 1 second.)-.1 E(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)
-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 29])-.15
E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(8.12. Older)72 84 R -1(Ve)
2.5 G(rsion Querier Pr)1 E(esent T)-.18 E(imeout)-.18 E F0(The Older V)
72 99.6 Q(ersion Querier Interv)-1.11 E(al is the time-out for transiti\
oning a host back to IGMPv3 mode once an)-.25 E(older v)72 111.6 Q
(ersion query is heard.)-.15 E(When an older v)5 E
(ersion query is recei)-.15 E -.15(ve)-.25 G(d, hosts set their Older V)
.15 E(ersion Querier)-1.11 E(Present T)72 123.6 Q(imer to Older V)-.35 E
(ersion Querier Interv)-1.11 E(al.)-.25 E(This v)72 139.2 Q
(alue MUST be \(\(the Rob)-.25 E(ustness V)-.2 E
(ariable\) times \(the Query Interv)-1.11 E(al in the last Query recei)
-.25 E -.15(ve)-.25 G(d\)\) plus).15 E(\(one Query Response Interv)72
151.2 Q(al\).)-.25 E F1 2.5(8.13. Older)72 187.2 R(Host Pr)2.5 E
(esent Inter)-.18 E -.1(va)-.1 G(l).1 E F0
(The Older Host Present Interv)72 202.8 Q(al is the time-out for transi\
tioning a group back to IGMPv3 mode once an)-.25 E(older v)72 214.8 Q
(ersion report is sent for that group.)-.15 E(When an older v)5 E
(ersion report is recei)-.15 E -.15(ve)-.25 G
(d, routers set their Older).15 E(Host Present T)72 226.8 Q
(imer to Older Host Present Interv)-.35 E(al.)-.25 E(This v)72 242.4 Q
(alue MUST be \(\(the Rob)-.25 E(ustness V)-.2 E
(ariable\) times \(the Query Interv)-1.11 E
(al\)\) plus \(one Query Response)-.25 E(Interv)72 254.4 Q(al\).)-.25 E
F1 2.5(8.14. Con\214guring)72 290.4 R(timers)2.5 E F0
(This section is meant to pro)72 306 Q(vide advice to netw)-.15 E
(ork administrators on ho)-.1 E 2.5(wt)-.25 G 2.5(ot)-2.5 G
(une these settings to their)-2.5 E(netw)72 318 Q 2.5(ork. Ambitious)-.1
F(router implementations might tune these settings dynamically based up\
on changing)2.5 E(characteristics of the netw)72 330 Q(ork.)-.1 E F1 2.5
(8.14.1. Rob)72 354 R(ustness V)-.2 E(ariable)-.92 E F0(The Rob)72 369.6
Q(ustness V)-.2 E(ariable tunes IGMP to e)-1.11 E
(xpected losses on a link.)-.15 E(IGMPv3 is rob)5 E(ust to \(Rob)-.2 E
(ustness)-.2 E -1.11(Va)72 381.6 S(riable - 1\) pack)1.11 E
(et losses, e.g. if the Rob)-.1 E(ustness V)-.2 E
(ariable is set to the def)-1.11 E(ault v)-.1 E
(alue of 2, IGMPv3 is rob)-.25 E(ust)-.2 E(to a single pack)72 393.6 Q
(et loss b)-.1 E(ut may operate imperfectly if more losses occur)-.2 E 5
(.O)-.55 G 2.5(nl)-5 G(ossy subnetw)-2.5 E(orks, the)-.1 E(Rob)72 405.6
Q(ustness V)-.2 E(ariable should be increased to allo)-1.11 E 2.5(wf)
-.25 G(or the e)-2.5 E(xpected le)-.15 E -.15(ve)-.25 G 2.5(lo).15 G 2.5
(fp)-2.5 G(ack)-2.5 E(et loss.)-.1 E(Ho)5 E(we)-.25 E -.15(ve)-.25 G -.4
(r,).15 G(increasing the Rob)72 417.6 Q(ustness V)-.2 E
(ariable increases the lea)-1.11 E .3 -.15(ve l)-.2 H(atenc).15 E 2.5
(yo)-.15 G 2.5(ft)-2.5 G(he subnetw)-2.5 E(ork \(the time between when)
-.1 E
(the last member stops listening to a source or group and when the traf)
72 429.6 Q(\214c stops \215o)-.25 E(wing.\))-.25 E F1 2.5(8.14.2. Query)
72 453.6 R(Inter)2.5 E -.1(va)-.1 G(l).1 E F0(The o)72 469.2 Q -.15(ve)
-.15 G(rall le).15 E -.15(ve)-.25 G 2.5(lo).15 G 2.5(fp)-2.5 G
(eriodic IGMP traf)-2.5 E(\214c is in)-.25 E -.15(ve)-.4 G
(rsely proportional to the Query Interv).15 E 2.5(al. A)-.25 F
(longer Query)2.5 E(Interv)72 481.2 Q(al results in a lo)-.25 E(wer o)
-.25 E -.15(ve)-.15 G(rall le).15 E -.15(ve)-.25 G 2.5(lo).15 G 2.5(fI)
-2.5 G(GMP traf)-2.5 E 2.5(\214c. The)-.25 F(Query Interv)2.5 E
(al MUST be equal to or longer)-.25 E(than the Max Response T)72 493.2 Q
(ime inserted in General Query messages.)-.35 E F1 2.5(8.14.3. Max)72
517.2 R(Response T)2.5 E(ime)-.18 E F0(The b)72 532.8 Q
(urstiness of IGMP traf)-.2 E(\214c is in)-.25 E -.15(ve)-.4 G
(rsely proportional to the Max Response T).15 E 2.5(ime. A)-.35 F
(longer Max)2.5 E(Response T)72 544.8 Q
(ime will spread Report messages o)-.35 E -.15(ve)-.15 G 2.5(ral).15 G
(onger interv)-2.5 E 2.5(al. Ho)-.25 F(we)-.25 E -.15(ve)-.25 G .8 -.4
(r, a l).15 H(onger Max Response T).4 E(ime)-.35 E
(in Group-Speci\214c and Source-and-Group-Speci\214c Queries e)72 556.8
Q(xtends the lea)-.15 E .3 -.15(ve l)-.2 H(atenc).15 E 2.5(y\()-.15 G
(the time between)-2.5 E(when the last member stops listening to a sour\
ce or group and when the traf)72 568.8 Q(\214c stops \215o)-.25 E 2.5
(wing.\) The)-.25 F -.15(ex)72 580.8 S
(pected rate of Report messages can be calculated by di).15 E
(viding the e)-.25 E(xpected number of)-.15 E(Cain, Deering, Fenner)72
768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43
(arajan [P)-.05 F(age 30])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(Reporters by the Max Response T)72 84 Q 2.5(ime. The)
-.35 F(Max Response T)2.5 E(ime may be dynamically calculated per Query)
-.35 E(by using the e)72 96 Q
(xpected number of Reporters for that Query as follo)-.15 E(ws:)-.25 E
/F1 10/Courier@0 SF(Query Type)90 120 Q(Expected number of Reporters)72
E 66(---------- ----------------------------)90 132 R(General Query)90
156 Q(All systems on subnetwork)54 E(Group-Specific Query)90 180 Q
(All systems that had expressed interest)12 E
(in the group on the subnetwork)234 192 Q 24(Source-and-Group- All)90
216 R(systems on the subnetwork that had)6 E(Specific Query)96 228 Q
(expressed interest in the source and group)54 E F0 2.5(Ar)72 252 S(out\
er is not required to calculate these populations or tune the Max Respo\
nse T)-2.5 E(ime dynamically; these)-.35 E(are simply guidelines.)72 264
Q/F2 10/Times-Bold@0 SF 2.5(9. SECURITY)72 312 R(CONSIDERA)2.5 E(TIONS)
-.95 E F0 1.6 -.8(We c)72 327.6 T(onsider the rami\214cations of a for)
.8 E(ged message of each type, and describe the usage of IPSEC AH to)
-.18 E(authenticate messages if desired.)72 339.6 Q F2 2.5(9.1. Query)72
363.6 R(Message)2.5 E F0 2.5(Af)72 379.2 S(or)-2.5 E
(ged Query message from a machine with a lo)-.18 E
(wer IP address than the current Querier will cause)-.25 E
(Querier duties to be assigned to the for)72 391.2 Q(ger)-.18 E 5(.I)
-.55 G 2.5(ft)-5 G(he for)-2.5 E
(ger then sends no more Query messages, other routers')-.18 E(Other Que\
rier Present timer will time out and one will resume the role of Querie\
r)72 403.2 Q 5(.D)-.55 G(uring this time, if the)-5 E(for)72 415.2 Q
(ger ignores Lea)-.18 E .3 -.15(ve M)-.2 H(essages, traf).15 E
(\214c might \215o)-.25 E 2.5(wt)-.25 G 2.5(og)-2.5 G
(roups with no members for up to [Group Membership)-2.5 E(Interv)72
427.2 Q(al].)-.25 E 2.5(AD)72 442.8 S
(oS attack on a host could be staged through for)-2.5 E
(ged Group-and-Source-Speci\214c Queries. The attack)-.18 E(er)-.1 E(ca\
n \214nd out about membership of a speci\214c host with a general query)
72 454.8 Q 2.5(.A)-.65 G(fter that it could send a lar)-2.5 E(ge)-.18 E
(number of Group-and-Source-Speci\214c queries, each with a lar)72 466.8
Q(ge source list and the Maximum Response)-.18 E -.35(Ti)72 478.8 S
(me set to a lar).35 E(ge v)-.18 E 2.5(alue. The)-.25 F(host will ha)2.5
E .3 -.15(ve t)-.2 H 2.5(os).15 G
(tore and maintain the sources speci\214ed in all of those)-2.5 E
(queries for as long as it tak)72 490.8 Q
(es to send the delayed response.)-.1 E(This w)5 E
(ould consume both memory and CPU)-.1 E -.15(cy)72 502.8 S(cles in orde\
r to augment the recorded sources with the source lists included in the\
 successi).15 E .3 -.15(ve q)-.25 H(ueries.).15 E 1.6 -.8(To p)72 518.4
T(rotect ag).8 E(ainst such a DoS attack, a host stack implementation c\
ould restrict the number of Group-and-)-.05 E
(Source-Speci\214c Queries per group membership within this interv)72
530.4 Q(al, and/or record only a limited number of)-.25 E(sources.)72
542.4 Q -.15(Fo)72 558 S -.18(rg).15 G
(ed Query messages from the local netw).18 E(ork can be easily traced.)
-.1 E(There are three measures necessary to)5 E(defend ag)72 570 Q
(ainst e)-.05 E(xternally for)-.15 E(ged Queries:)-.18 E 5(oR)72 585.6 S
(outers SHOULD NO)-5 E 2.5(Tf)-.4 G(orw)-2.5 E(ard Queries. This is eas\
ier for a router to accomplish if the Query carries)-.1 E(the Router)82
597.6 Q(-Alert option.)-.2 E 5(oH)72 613.2 S
(osts SHOULD ignore v2 or v3 Queries without the Router)-5 E
(-Alert option.)-.2 E 5(oH)72 628.8 S(osts SHOULD ignore v1, v2 or v3 G\
eneral Queries sent to a multicast address other than 224.0.0.1, the)-5
E(all-systems address.)82 640.8 Q F2 2.5(9.2. Curr)72 676.8 R
(ent-State Report messages)-.18 E F0 2.5(Af)72 692.4 S(or)-2.5 E(ged Re\
port message may cause multicast routers to think there are members of \
a group on a netw)-.18 E(ork)-.1 E(when there are not.)72 704.4 Q -.15
(Fo)5 G -.18(rg).15 G(ed Report messages from the local netw).18 E
(ork are meaningless, since joining a group)-.1 E
(on a host is generally an unpri)72 716.4 Q(vile)-.25 E
(ged operation, so a local user may tri)-.15 E(vially g)-.25 E
(ain the same result without)-.05 E(Cain, Deering, Fenner)72 768 Q 2.5
(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F
(age 31])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(for)72 84 Q(ging an)-.18 E 2.5(ym)-.15 G 2.5
(essages. F)-2.5 F(or)-.15 E(ged Report messages from e)-.18 E
(xternal sources are more troublesome; there are tw)-.15 E(o)-.1 E
(defenses ag)72 96 Q(ainst e)-.05 E(xternally for)-.15 E(ged Reports:)
-.18 E 5(oI)72 111.6 S
(gnore the Report if you cannot identify the source address of the pack)
-5 E(et as belonging to a netw)-.1 E(ork)-.1 E(assigned to the interf)82
123.6 Q(ace on which the pack)-.1 E(et w)-.1 E(as recei)-.1 E -.15(ve)
-.25 G 2.5(d. This).15 F(solution means that Reports sent by)2.5 E
(mobile hosts without addresses on the local netw)82 135.6 Q
(ork will be ignored.)-.1 E(Report messages with a source)5 E
(address of 0.0.0.0 SHOULD be accepted on an)82 147.6 Q 2.5(yi)-.15 G
(nterf)-2.5 E(ace.)-.1 E 5(oI)72 163.2 S(gnore Report messages without \
Router Alert options [RFC-2113], and require that routers not forw)-5 E
(ard)-.1 E(Report messages.)82 175.2 Q(\(The requirement is not a requi\
rement of generalized \214ltering in the forw)5 E(arding path,)-.1 E
(since the pack)82 187.2 Q(ets already ha)-.1 E .3 -.15(ve R)-.2 H
(outer Alert options in them\).).15 E(This solution breaks backw)5 E
(ards)-.1 E(compatibility with implementations of IGMPv1 or earlier v)82
199.2 Q(ersions of IGMPv2 which did not require)-.15 E(Router Alert.)82
211.2 Q 2.5(Af)72 226.8 S(or)-2.5 E(ged V)-.18 E
(ersion 1 Report Message may put a router into "v)-1.11 E
(ersion 1 members present" state for a particular)-.15 E
(group, meaning that the router will ignore Lea)72 238.8 Q .3 -.15(ve m)
-.2 H 2.5(essages. This).15 F(can cause traf)2.5 E(\214c to \215o)-.25 E
2.5(wt)-.25 G 2.5(og)-2.5 G(roups with no)-2.5 E
(members for up to [Group Membership Interv)72 250.8 Q 2.5(al]. This)
-.25 F(can be solv)2.5 E(ed by pro)-.15 E(viding routers with a)-.15 E
(con\214guration switch to ignore V)72 262.8 Q
(ersion 1 messages completely)-1.11 E 5(.T)-.65 G
(his breaks automatic compatibility with)-5 E -1.11(Ve)72 274.8 S
(rsion 1 hosts, so should only be used in situations where "f)1.11 E
(ast lea)-.1 E -.15(ve)-.2 G 2.5("i).15 G 2.5(sc)-2.5 G(ritical.)-2.5 E
2.5(Af)72 290.4 S(or)-2.5 E(ged V)-.18 E
(ersion 2 Report Message may put a router into "v)-1.11 E
(ersion 2 members present" state for a particular)-.15 E(group, meaning\
 that the router will ignore IGMPv3 source-speci\214c state messages.)72
302.4 Q(This can cause traf)5 E(\214c to)-.25 E<8d6f>72 314.4 Q 2.5(wf)
-.25 G(rom unw)-2.5 E(anted sources for up to [Group Membership Interv)
-.1 E 2.5(al]. This)-.25 F(can be solv)2.5 E(ed by pro)-.15 E(viding)
-.15 E(routers with a con\214guration switch to ignore V)72 326.4 Q
(ersion 2 messages completely)-1.11 E 5(.T)-.65 G(his breaks automatic)
-5 E(compatibility with V)72 338.4 Q(ersion 2 hosts, so should only be \
used in situations where source include and e)-1.11 E(xclude is)-.15 E
(critical.)72 350.4 Q/F1 10/Times-Bold@0 SF 2.5(9.3. State-Change)72
374.4 R(Report messages)2.5 E F0 2.5(Af)72 390 S(or)-2.5 E(ged State-Ch\
ange Report message will cause the Querier to send out Group-Speci\214c\
 or Source-and-)-.18 E
(Group-Speci\214c Queries for the group in question.)72 402 Q
(This causes e)5 E(xtra processing on each router and on each)-.15 E
(member of the group, b)72 414 Q(ut can not cause loss of desired traf)
-.2 E 2.5(\214c. There)-.25 F(are tw)2.5 E 2.5(od)-.1 G(efenses ag)-2.5
E(ainst e)-.05 E(xternally)-.15 E(for)72 426 Q
(ged State-Change Report messages:)-.18 E 5(oI)72 441.6 S(gnore the Sta\
te-Change Report message if you cannot identify the source address of t\
he pack)-5 E(et as)-.1 E(belonging to a subnet assigned to the interf)82
453.6 Q(ace on which the pack)-.1 E(et w)-.1 E(as recei)-.1 E -.15(ve)
-.25 G 2.5(d. This).15 F(solution means)2.5 E(that State-Change Report \
messages sent by mobile hosts without addresses on the local subnet wil\
l be)82 465.6 Q 2.5(ignored. State-Change)82 477.6 R(Report messages wi\
th a source address of 0.0.0.0 SHOULD be accepted on an)2.5 E(y)-.15 E
(interf)82 489.6 Q(ace.)-.1 E 5(oI)72 505.2 S(gnore State-Change Report\
 messages without Router Alert options [RFC-2113], and require that rou\
ters)-5 E(not forw)82 517.2 Q(ard State-Change Report messages.)-.1 E
(\(The requirement is not a requirement of generalized)5 E
(\214ltering in the forw)82 529.2 Q(arding path, since the pack)-.1 E
(ets already ha)-.1 E .3 -.15(ve R)-.2 H(outer Alert options in them\).)
.15 E F1 2.5(9.4. IPSEC)72 553.2 R(Usage)2.5 E F0(In addition to these \
measures, IPSEC in Authentication Header mode [AH] may be used to prote\
ct ag)72 568.8 Q(ainst)-.05 E(remote attacks by ensuring that IGMPv3 me\
ssages came from a system on the LAN \(or)72 580.8 Q 2.5(,m)-.4 G
(ore speci\214cally)-2.5 E 2.5(,a)-.65 G(system with the proper k)72
592.8 Q -.15(ey)-.1 G 2.5(\). When).15 F
(using IPSEC, the messages sent to 224.0.0.1 and 224.0.0.22 should be)
2.5 E(authenticated using AH.)72 604.8 Q(When k)5 E -.15(ey)-.1 G
(ing, there are tw).15 E 2.5(op)-.1 G(ossibilities:)-2.5 E 5(1. Use)72
620.4 R 2.5(as)2.5 G(ymmetric signature algorithm with a single k)-2.5 E
.3 -.15(ey f)-.1 H(or the LAN \(or a k).15 E .3 -.15(ey f)-.1 H
(or each group\).).15 E(This)5 E(allo)87 632.4 Q(ws v)-.25 E
(alidation that a pack)-.25 E(et w)-.1 E(as sent by a system with the k)
-.1 E -.15(ey)-.1 G 5(.T)-.5 G(his has the limitation that an)-5 E(y)
-.15 E(system with the k)87 644.4 Q .3 -.15(ey c)-.1 H(an for).15 E
(ge a message; it is not possible to authenticate the indi)-.18 E
(vidual sender)-.25 E(precisely)87 656.4 Q 5(.I)-.65 G 2.5(ta)-5 G
(lso requires disabling IPSec')-2.5 E 2.5(sR)-.55 G(eplay Protection.)
-2.5 E 5(2. When)72 672 R(appropriate k)2.5 E .3 -.15(ey m)-.1 H
(anagement standards ha).15 E .3 -.15(ve b)-.2 H(een de).15 E -.15(ve)
-.25 G(loped, use an asymmetric signature).15 E 2.5(algorithm. All)87
684 R(systems need to kno)2.5 E 2.5(wt)-.25 G(he public k)-2.5 E .3 -.15
(ey o)-.1 H 2.5(fa).15 G(ll routers, and all routers need to kno)-2.5 E
2.5(wt)-.25 G(he)-2.5 E(public k)87 696 Q .3 -.15(ey o)-.1 H 2.5(fa).15
G(ll systems.)-2.5 E(This requires a lar)5 E(ge amount of k)-.18 E .3
-.15(ey m)-.1 H(anagement b).15 E(ut has the adv)-.2 E(antage that)-.25
E(senders can be authenticated indi)87 708 Q
(vidually so e.g. a host cannot for)-.25 E
(ge a message that only routers should)-.18 E(be allo)87 720 Q
(wed to send.)-.25 E(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)
-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 32])-.15
E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E(This solution only directly applies to Query and Lea)
72 84 Q .3 -.15(ve m)-.2 H(essages in IGMPv1 and IGMPv2, since Reports)
.15 E(are sent to the group being reported and it is not feasible to ag\
ree on a k)72 96 Q .3 -.15(ey f)-.1 H(or host-to-router).15 E
(communication for arbitrary multicast groups.)72 108 Q/F1 10
/Times-Bold@0 SF 2.5(10. IAN)72 144 R 2.5(AC)-.2 G(ONSIDERA)-2.5 E
(TIONS)-.95 E F0
(All IGMP types described in this document are already assigned in [IAN)
72 159.6 Q 2.5(A-REG]. The)-.35 F(IAN)2.5 E 2.5(Ai)-.35 G 2.5(sr)-2.5 G
(equested)-2.5 E(to replace the [RFCIGMPv3] references with a reference\
 to this document')72 171.6 Q 2.5(sR)-.55 G(FC number when published.)
-2.5 E F1 2.5(11. A)72 195.6 R(CKNO)-.55 E(WLEDGMENTS)-.5 E F0 1.6 -.8
(We w)72 211.2 T(ould lik).7 E 2.5(et)-.1 G 2.5(ot)-2.5 G
(hank Ran Atkinson, Luis Costa, T)-2.5 E(oerless Eck)-.8 E(ert, Dino F)
-.1 E(arinacci, Ser)-.15 E(ge Fdida, W)-.18 E(ilbert de)-.4 E
(Graaf, Sumit Gupta, Mark Handle)72 223.2 Q 1.3 -.65(y, B)-.15 H
(ob Quinn, Michael Speer).65 E 2.5(,D)-.4 G -2.25 -.2(av e)-2.5 H
(Thaler and Rolland V)2.7 E(ida for)-.6 E
(comments and suggestions on this document.)72 235.2 Q
(Portions of the te)72 250.8 Q
(xt of this document were copied from [RFC-1112] and [RFC-2236].)-.15 E
F1 2.5(12. Normati)72 286.8 R .2 -.1(ve R)-.1 H(efer).1 E(ences)-.18 E
20([AH] K)72 310.8 R(ent, S. and R. Atkinson, "IP A)-.25 E
(uthentication Header",)-.5 E(RFC 2402, No)104.5 322.8 Q -.1(ve)-.1 G
(mber 1998.).1 E([IAN)72 346.8 Q 5(A-REG] http://www)-.2 F(.iana.or)-.7
E(g/assignments/igmp-type-numbers)-.1 E 5([RFC-1112] Deering,)72 370.8 R
(S., "Host Extensions f)2.5 E(or IP Multicasting", RFC 1112,)-.25 E -.5
(Au)104.5 382.8 S(gust 1989.).5 E 5([RFC-2113] Katz,)72 406.8 R -.2(D.)
2.5 G 2.5(,").2 G(IP Router Alert Option," RFC 2113, A)-2.5 E
(pril 1996.)-.25 E 5([RFC-2119] Bradner)72 430.8 R 2.5(,S)-.92 G(., "K)
-2.5 E(ey w)-.25 E(ords f)-.1 E(or use in RFCs to Indicate)-.25 E
(Requir)104.5 442.8 Q(ement Le)-.18 E -.1(ve)-.15 G
(ls", RFC 2119, BCP14, Mar).1 E(ch 1997.)-.18 E 5([RFC-2236] F)72 466.8
R(enner)-.25 E 2.5(,W)-.92 G(., "Inter)-3.42 E(net Gr)-.15 E
(oup Management Pr)-.18 E(otocol, V)-.18 E(ersion 2",)-1 E(RFC 2236, No)
104.5 478.8 Q -.1(ve)-.1 G(mber 1997.).1 E 5([RFC-3228] F)72 502.8 R
(enner)-.25 E 2.5(,B)-.92 G(., "IAN)-2.5 E 2.5(AC)-.2 G(onsiderations f)
-2.5 E(or IPv4 Inter)-.25 E(net Gr)-.15 E(oup)-.18 E(Management Pr)104.5
514.8 Q(otocol \(IGMP\)", RFC 3228, F)-.18 E(ebruary 2002.)-.25 E F0
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 33])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF 2.5(13. Inf)72 84 R(ormati)-.25
E .2 -.1(ve R)-.1 H(efer).1 E(ences)-.18 E 5([RFC-1071] Braden,)72 108 R
(R.T)2.5 E(., D)-.9 E(.A. Borman, C.)-.2 E -.1(Pa)5 G
(rtridge, "Computing the).1 E(Inter)104.5 120 Q
(net checksum", RFC 1071, September 1988.)-.15 E([FIL)72 144 Q
(TER-API] Thaler)-.92 E 2.5(,D)-.92 G(., B. F)-2.7 E(enner)-.25 E 2.5
(,a)-.92 G(nd B. Quinn, "Sock)-2.5 E(et Interface)-.1 E(Extensions f)
104.5 156 Q(or Multicast Sour)-.25 E(ce Filters", W)-.18 E(ork in pr)
-.75 E(ogr)-.18 E(ess,)-.18 E -.15(Ju)104.5 168 S(ly 2001.).15 E 17.5
([SSM] Bhattacharyya,)72 192 R(S. et al., "An Ov)2.5 E(er)-.1 E
(view of Sour)-.1 E(ce-Speci\214c)-.18 E(Multicast \(SSM\)", W)104.5 204
Q(ork in pr)-.75 E(ogr)-.18 E(ess, Mar)-.18 E(ch 2002.)-.18 E 17.5
([MLD] Deering,)72 228 R(S., W)2.5 E 2.5(.F)-.92 G(enner)-2.75 E 2.5(,a)
-.92 G(nd B. Haberman, "Multicast Listener)-2.5 E(Disco)104.5 240 Q -.1
(ve)-.1 G(ry \(MLD\) f).1 E(or IPv6", RFC 2710, October 1999.)-.25 E
([MLD)72 264 Q 12.5(V2] V)-.4 F
(ida, R., L. Costa, S. Fdida, S. Deering, B. F)-.37 E(enner)-.25 E 2.5
(,I)-.92 G 2.5(.K)-2.5 G(ouv)-2.75 E(elas,)-.1 E
(and B. Haberman, "Multicast Listener Disco)104.5 276 Q -.1(ve)-.1 G
(ry V).1 E(ersion 2)-1 E(\(MLDv2\) f)104.5 288 Q(or IPv6", w)-.25 E
(ork in pr)-.1 E(ogr)-.18 E(ess, J)-.18 E(anuary 2002.)-.15 E F0
(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E
(yag)-.05 E 205.43(arajan [P)-.05 F(age 34])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF(APPENDIX A.)72 84 Q(DESIGN RA)5
E(TION)-.95 E(ALE)-.2 E 2.5(A.1 The)72 120 R(Need f)2.5 E
(or State-Change Messages)-.25 E F0(IGMPv3 speci\214es tw)72 135.6 Q 2.5
(ot)-.1 G(ypes of Membership Reports: Current-State and State Change.)
-2.5 E(This section)5 E
(describes the rationale for the need for both these types of Reports.)
72 147.6 Q(Routers need to distinguish Membership Reports that were sen\
t in response to Queries from those that were)72 163.2 Q
(sent as a result of a change in interf)72 175.2 Q(ace state.)-.1 E
(Membership reports that are sent in response to Membership)5 E
(Queries are used mainly to refresh the e)72 187.2 Q
(xisting state at the router; the)-.15 E 2.5(yt)-.15 G
(ypically do not cause transitions in)-2.5 E(state at the router)72
199.2 Q 5(.M)-.55 G
(embership Reports that are sent in response to changes in interf)-5 E
(ace state require the)-.1 E(router to tak)72 211.2 Q 2.5(es)-.1 G
(ome action in response to the recei)-2.5 E -.15(ve)-.25 G 2.5(dr).15 G
(eport \(see Section 6.4\).)-2.5 E
(The inability to distinguish between the tw)72 226.8 Q 2.5(ot)-.1 G
(ypes of reports w)-2.5 E(ould force a router to treat all Membership)
-.1 E(Reports as potential changes in state and could result in increas\
ed processing at the router as well as an)72 238.8 Q
(increase in IGMP traf)72 250.8 Q(\214c on the netw)-.25 E(ork.)-.1 E F1
2.5(A.2 Host)72 286.8 R(Suppr)2.5 E(ession)-.18 E F0
(In IGMPv1 and IGMPv2, a host w)72 302.4 Q
(ould cancel sending a pending membership reports if a similar report w)
-.1 E(as)-.1 E(observ)72 314.4 Q(ed from another member on the netw)-.15
E 2.5(ork. In)-.1 F(IGMPv3, this suppression of host membership reports)
2.5 E(has been remo)72 326.4 Q -.15(ve)-.15 G 2.5(d. The).15 F(follo)2.5
E(wing points e)-.25 E(xplain the reasons behind this decision.)-.15 E 5
(1. Routers)72 342 R(may w)2.5 E(ant to track per)-.1 E
(-host membership status on an interf)-.2 E 2.5(ace This)-.1 F(allo)2.5
E(ws routers to implement)-.25 E -.1(fa)87 354 S(st lea).1 E -.15(ve)-.2
G 2.5(s\().15 G 2.5(e.g. for)-2.5 F(layered multicast congestion contro\
l schemes\) as well as track membership status)2.5 E
(for possible accounting purposes.)87 366 Q 5(2. Membership)72 381.6 R
(Report suppression does not w)2.5 E(ork well on bridged LANs.)-.1 E
(Man)5 E 2.5(yb)-.15 G(ridges and)-2.5 E
(Layer2/Layer3 switches that implement IGMP snooping do not forw)87
393.6 Q(ard IGMP messages across LAN)-.1 E(se)87 405.6 Q
(gments in order to pre)-.15 E -.15(ve)-.25 G
(nt membership report suppression.).15 E(Remo)5 E
(ving membership report)-.15 E
(suppression eases the job of these IGMP snooping de)87 417.6 Q(vices.)
-.25 E 5(3. By)72 433.2 R
(eliminating membership report suppression, hosts ha)2.5 E .3 -.15(ve f)
-.2 H -.25(ew).15 G(er messages to process; this leads to a).25 E
(simpler state machine implementation.)87 445.2 Q 5(4. In)72 460.8 R
(IGMPv3, a single membership report no)2.5 E 2.5(wb)-.25 G
(undles multiple multicast group records to decrease the)-2.7 E
(number of pack)87 472.8 Q(ets sent.)-.1 E(In comparison, the pre)5 E
(vious v)-.25 E(ersions of IGMP required that each multicast)-.15 E
(group be reported in a separate message.)87 484.8 Q F1(A.3 Switching r)
72 520.8 Q(outer \214lter modes fr)-.18 E(om EXCLUDE to INCLUDE)-.18 E
F0(If there e)72 536.4 Q(xist hosts in both EXCLUDE and INCLUDE modes f\
or a single multicast group in a netw)-.15 E(ork, the)-.1 E
(router must be in EXCLUDE mode as well \(see section 6.2.1\).)72 548.4
Q(In EXCLUDE mode, a router forw)5 E(ards)-.1 E(traf)72 560.4 Q
(\214c from all sources unless that source e)-.25 E(xists in the e)-.15
E(xclusion source list.)-.15 E(If all hosts in EXCLUDE)5 E
(mode cease to e)72 572.4 Q(xist, it w)-.15 E(ould be desirable for the\
 router to switch back to INCLUDE mode seamlessly)-.1 E
(without interrupting the \215o)72 584.4 Q 2.5(wo)-.25 G 2.5(ft)-2.5 G
(raf)-2.5 E(\214c to e)-.25 E(xisting recei)-.15 E -.15(ve)-.25 G(rs.)
.15 E(One of the w)72 600 Q(ays to accomplish this is for routers to k)
-.1 E(eep track of all sources desired by hosts that are in)-.1 E
(INCLUDE mode e)72 612 Q -.15(ve)-.25 G 2.5(nt).15 G
(hough the router itself is in EXCLUDE mode.)-2.5 E
(If the group timer no)5 E 2.5(we)-.25 G(xpires in)-2.65 E(EXCLUDE mode\
, it implies that there are no hosts in EXCLUDE mode on the netw)72 624
Q(ork \(otherwise a)-.1 E(membership report from that host w)72 636 Q
(ould ha)-.1 E .3 -.15(ve r)-.2 H(efreshed the group timer\).).15 E
(The router can then switch to)5 E
(INCLUDE mode seamlessly with the list of sources currently being forw)
72 648 Q(arded in its source list.)-.1 E(Cain, Deering, Fenner)72 768 Q
2.5(,K)-.4 G(ouv)-2.85 E(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)
-.05 F(age 35])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF(APPENDIX B.)72 84 Q(SUMMAR)5 E
2.5(YO)-.35 G 2.5(FC)-2.5 G(HANGES FR)-2.5 E(OM IGMPv2)-.3 E F0(While t\
he main additional feature of IGMPv3 is the addition of source \214lter\
ing, the follo)72 99.6 Q(wing is a summary)-.25 E
(of other changes from RFC 2236.)72 111.6 Q 5(oS)72 127.2 S(tate is mai\
ntained as Group + List-of-Sources, not simply Group as in IGMPv2.)-5 E
5(oI)82 142.8 S(nteroperability with IGMPv1 and IGMPv2 systems is de\
\214ned as operations on the IGMPv3 state.)-5 E 5(oT)72 158.4 S
(he IP Service Interf)-5 E(ace has changed to allo)-.1 E 2.5(ws)-.25 G
(peci\214cation of source-lists.)-2.5 E 5(oT)72 174 S
(he Querier includes its Rob)-5 E(ustness V)-.2 E
(ariable and Query Interv)-1.11 E(al in Query pack)-.25 E(ets to allo)
-.1 E(w)-.25 E(synchronization of these v)82 186 Q
(ariables on non-Queriers.)-.25 E 5(oT)72 201.6 S(he Max Response T)-5 E
(ime in Query messages has an e)-.35 E
(xponential range, changing the maximum from 25.5)-.15 E(seconds to abo\
ut 53 minutes, for use on links with huge numbers of systems.)82 213.6 Q
5(oH)72 229.2 S(osts retransmit state-change messages for increased rob)
-5 E(ustness.)-.2 E 5(oA)72 244.8 S
(dditional data sections are de\214ned to allo)-5 E 2.5(wl)-.25 G
(ater e)-2.5 E(xtensions.)-.15 E 5(oR)72 260.4 S(eport pack)-5 E
(ets are sent to 224.0.0.22, to assist layer)-.1 E
(-2 switches in "snooping".)-.2 E 5(oR)72 276 S(eport pack)-5 E
(ets can contain multiple group records, to allo)-.1 E 2.5(wr)-.25 G
(eporting of full current state using fe)-2.5 E(wer)-.25 E(pack)82 288 Q
(ets.)-.1 E 5(oH)72 303.6 S(osts no longer perform suppression, to simp\
lify implementations and permit e)-5 E(xplicit membership)-.15 E
(tracking.)82 315.6 Q 5(oN)72 331.2 S .5 -.25(ew S)-5 H(uppress Router)
.25 E(-Side Processing \(S\) \215ag in Query messages \214x)-.2 E
(es rob)-.15 E(ustness issues which were)-.2 E(also present in IGMPv2.)
82 343.2 Q(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E
(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 36])-.15 E EP
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/F0 10/Times-Roman@0 SF(INTERNET)72 48 Q 111.93(-DRAFT IGMPv3)-.92 F
(May 2002)157.67 E/F1 10/Times-Bold@0 SF -.5(AU)72 84 S
(THORS' ADDRESSES).5 E F0(Brad Cain)79.5 99.6 Q(Cere)79.5 111.6 Q .5
-.25(va N)-.25 H(etw).25 E(orks)-.1 E(Email: bcain@cere)79.5 123.6 Q
-.25(va)-.25 G(.com).25 E(Ste)79.5 147.6 Q .3 -.15(ve D)-.25 H(eering)
.15 E(Cisco Systems, Inc.)79.5 159.6 Q(170 T)79.5 171.6 Q(asman Dri)-.8
E -.15(ve)-.25 G(San Jose, CA 95134-1706)79.5 183.6 Q
(phone: +1-408-527-8213)79.5 195.6 Q(email: deering@cisco.com)79.5 207.6
Q(Bill Fenner)79.5 231.6 Q -1.11(AT)79.5 243.6 S(&T Labs - Research)1.11
E(75 W)79.5 255.6 Q(illo)-.4 E 2.5(wR)-.25 G(d.)-2.5 E(Menlo P)79.5
267.6 Q(ark, CA 94025)-.15 E(phone: +1-650-330-7893)79.5 279.6 Q
(email: fenner@research.att.com)79.5 291.6 Q(Isidor K)79.5 315.6 Q(ouv)
-.35 E(elas)-.15 E(Cisco Systems, Inc.)79.5 327.6 Q(170 T)79.5 339.6 Q
(asman Dri)-.8 E -.15(ve)-.25 G(San Jose, CA 95134-1706)79.5 351.6 Q
(phone: +1-408-525-0727)79.5 363.6 Q(email: k)79.5 375.6 Q(ouv)-.1 E
(elas@cisco.com)-.15 E(Ajit Th)79.5 399.6 Q(yag)-.05 E(arajan)-.05 E
(Ericsson IP Infrastructure)79.5 411.6 Q(12120 Plum Orchard Dr)79.5
423.6 Q(.)-.55 E(Silv)79.5 435.6 Q(er Spring, MD 20904)-.15 E
(phone: +1-301-586-8200)79.5 447.6 Q(email: ajit@torrentnet.com)79.5
459.6 Q(Cain, Deering, Fenner)72 768 Q 2.5(,K)-.4 G(ouv)-2.85 E
(elas, Th)-.15 E(yag)-.05 E 205.43(arajan [P)-.05 F(age 37])-.15 E EP
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