idnits 2.17.00 (12 Aug 2021) /tmp/idnits53896/draft-ietf-msdp-spec-07.txt: ** The Abstract section seems to be numbered Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** Looks like you're using RFC 2026 boilerplate. This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- ** Missing expiration date. The document expiration date should appear on the first and last page. ** The document seems to lack a 1id_guidelines paragraph about Internet-Drafts being working documents. ** The document is more than 15 pages and seems to lack a Table of Contents. == No 'Intended status' indicated for this document; assuming Proposed Standard == The page length should not exceed 58 lines per page, but there was 26 longer pages, the longest (page 2) being 60 lines == It seems as if not all pages are separated by form feeds - found 0 form feeds but 27 pages Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an Introduction section. ** The document seems to lack separate sections for Informative/Normative References. All references will be assumed normative when checking for downward references. ** There are 12 instances of too long lines in the document, the longest one being 7 characters in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year == The document seems to lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords. (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: RPs which originate SA messages do it periodically as long as there is data being sent by the source. There is one SA-Advertisement-Timer covering the sources that an RP may advertise. [SA-Advertisement-Period] MUST be 60 seconds. An RP MUST not send more than one periodic SA message for a given (S,G) within an SA Advertisement interval. Originating periodic SA messages is important so that new receivers who join after a source has been active can get data quickly via the receiver's own RP. Finally, an originating RP SHOULD trigger the transmission of an SA message as soon as it receives data from an internal source for the first time. -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- Couldn't find a document date in the document -- date freshness check skipped. Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'SA-Advertisement-Period' is mentioned on line 165, but not defined == Missing Reference: 'SA-State-Period' is mentioned on line 183, but not defined == Missing Reference: 'SA-Hold-Down-Period' is mentioned on line 191, but not defined == Missing Reference: 'KeepAlive-Period' is mentioned on line 201, but not defined == Missing Reference: 'ConnectRetry-Period' is mentioned on line 212, but not defined == Missing Reference: 'Hold-Time-Period' is mentioned on line 225, but not defined == Missing Reference: 'MSDP-GRE-ProtocolType' is mentioned on line 910, but not defined == Unused Reference: 'RFC1700' is defined on line 985, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. 'IANA' ** Obsolete normative reference: RFC 1700 (Obsoleted by RFC 3232) ** Obsolete normative reference: RFC 1771 (Obsoleted by RFC 4271) ** Obsolete normative reference: RFC 1825 (Obsoleted by RFC 2401) ** Downref: Normative reference to an Historic RFC: RFC 1828 ** Obsolete normative reference: RFC 2283 (Obsoleted by RFC 2858) ** Obsolete normative reference: RFC 2362 (Obsoleted by RFC 4601, RFC 5059) Summary: 14 errors (**), 0 flaws (~~), 14 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group David Meyer (Editor) 3 INTERNET DRAFT 4 Category Standards Track 5 March, 2001 7 Multicast Source Discovery Protocol (MSDP) 8 10 1. Status of this Memo 12 This document is an Internet-Draft and is in full conformance with 13 all provisions of Section 10 of RFC 2026. 15 Internet Drafts are working documents of the Internet Engineering 16 Task Force (IETF), its areas, and its working groups. Note that other 17 groups may also distribute working documents as Internet-Drafts. 19 Internet-Drafts are draft documents valid for a maximum of six months 20 and may be updated, replaced, or obsoleted by other documents at any 21 time. It is inappropriate to use Internet-Drafts as reference 22 material or to cite them other than as "work in progress." 24 The list of current Internet-Drafts can be accessed at 25 http://www.ietf.org/ietf/1id-abstracts.txt. 27 The list of Internet-Draft Shadow Directories can be accessed at 28 http://www.ietf.org/shadow.html. 30 2. Abstract 32 The Multicast Source Discovery Protocol, MSDP, describes a mechanism 33 to connect multiple PIM-SM domains together. Each PIM-SM domain uses 34 its own independent RP(s) and does not have to depend on RPs in other 35 domains. 37 3. Copyright Notice 39 Copyright (C) The Internet Society (2000). All Rights Reserved. 41 4. Introduction 43 The Multicast Source Discovery Protocol, MSDP, describes a mechanism 44 to connect multiple PIM-SM domains together. Each PIM-SM domain uses 45 its own independent RP(s) and does not have to depend on RPs in other 46 domains. Advantages of this approach include: 48 o No Third-party resource dependencies on RP 50 PIM-SM domains can rely on their own RPs only. 52 o Receiver only Domains 54 Domains with only receivers get data without globally 55 advertising group membership. 57 The keywords MUST, MUST NOT, MAY, OPTIONAL, REQUIRED, RECOMMENDED, 58 SHALL, SHALL NOT, SHOULD, SHOULD NOT are to be interpreted as defined 59 in RFC 2119 [RFC2119]. 61 5. Overview 63 MSDP-speaking routers in a PIM-SM [RFC2362] domain will have a MSDP 64 peering relationship with MSDP peers in another domain. The peering 65 relationship will be made up of a TCP connection in which control 66 information is exchanged. Each domain will have one or more 67 connections to this virtual topology. 69 The purpose of this topology is to allow domains discover multicast 70 sources from other domains. If the multicast sources are of interest 71 to a domain which has receivers, the normal source-tree building 72 mechanism in PIM-SM will be used to deliver multicast data over an 73 inter-domain distribution tree. 75 We envision this virtual topology will essentially be congruent to 76 the existing BGP topology used in the unicast-based Internet today. 77 That is, the TCP connections between MSDP peers are likely to be 78 congruent to the connections in the BGP routing system. 80 6. Procedure 82 A source in a PIM-SM domain originates traffic to a multicast group. 83 The PIM DR which is directly connected to the source sends the data 84 encapsulated in a PIM Register message to the RP in the domain. 86 The RP will construct a "Source-Active" (SA) message and send it to 87 its MSDP peers. The SA message contains the following fields: 89 o Source address of the data source. 90 o Group address the data source sends to. 91 o IP address of the RP. 93 Each MSDP peer receives and forwards the message away from the RP 94 address in a "peer-RPF flooding" fashion. The notion of peer-RPF 95 flooding is with respect to forwarding SA messages. The BGP routing 96 table is examined to determine which peer is the NEXT_HOP towards the 97 originating RP of the SA message. Such a peer is called an "RPF 98 peer". See section 14 below for the details of peer-RPF forwarding. 100 If the MSDP peer receives the SA from a non-RPF peer towards the 101 originating RP, it will drop the message. Otherwise, it forwards the 102 message to all its MSDP peers (except the one from which it received 103 the SA message). 105 The flooding can be further constrained to children of the peer by 106 interrogating BGP reachability information. That is, if a BGP peer 107 advertises a route (back to you) and you are the next to last AS in 108 the AS_PATH, the peer is using you as the NEXT_HOP. This is known in 109 other circles as Split-Horizon with Poison Reverse. An implementation 110 SHOULD NOT forward SA messages (which were originated from the RP 111 address covered by a route) to peers which have not Poison Reversed 112 that route. 114 When an MSDP peer which is also an RP for its own domain receives a 115 new SA message, it determines if it has any group members interested 116 in the group which the SA message describes. That is, the RP checks 117 for a (*,G) entry with a non-empty outgoing interface list; this 118 implies that the domain is interested in the group. In this case, the 119 RP triggers a (S,G) join event towards the data source as if a 120 Join/Prune message was received addressed to the RP itself. This sets 121 up a branch of the source-tree to this domain. Subsequent data 122 packets arrive at the RP which are forwarded down the shared-tree 123 inside the domain. If leaf routers choose to join the source-tree 124 they have the option to do so according to existing PIM-SM 125 conventions. Finally, if an RP in a domain receives a PIM Join 126 message for a new group G, the RP SHOULD trigger a (S,G) join event 127 for each SA for that group in its cache. 129 This procedure has been affectionately named flood-and-join because 130 if any RP is not interested in the group, they can ignore the SA 131 message. Otherwise, they join a distribution tree. 133 7. Caching 135 A MSDP speaker MUST cache SA messages. Caching allows pacing of MSDP 136 messages as well as reducing join latency for new receivers of a 137 group G at an orginating RP which has existing MSDP (S,G) state. In 138 addition, caching greatly aids in diagnosis and debugging of various 139 problems. 141 8. Timers 143 The main timers for MSDP are: SA-Advertisement-Timer, SA-Hold-Down- 144 Timer, SA Cache Entry timer, KeepAlive timer, and ConnectRetry and 145 Peer Hold Timer. Each is considered below. 147 8.1. SA-Advertisement-Timer 149 RPs which originate SA messages do it periodically as long as there 150 is data being sent by the source. There is one SA-Advertisement-Timer 151 covering the sources that an RP may advertise. [SA-Advertisement- 152 Period] MUST be 60 seconds. An RP MUST not send more than one 153 periodic SA message for a given (S,G) within an SA Advertisement 154 interval. Originating periodic SA messages is important so that new 155 receivers who join after a source has been active can get data 156 quickly via the receiver's own RP. Finally, an originating RP SHOULD 157 trigger the transmission of an SA message as soon as it receives data 158 from an internal source for the first time. 160 8.2. SA-Advertisement-Timer Processing 162 An RP MUST spread the generation of periodic SA messages over its 163 reporting interval (i.e. SA-Advertisement-Period). An RP starts the 164 SA-Advertisement-Timer when the MSDP process is configured. When the 165 timer expires, an RP resets the timer to [SA-Advertisement-Period] 166 seconds, and begins the advertisement of its active sources. Active 167 sources are advertised in the following manner: An RP packs its 168 active sources into an SA message until the largest MSDP packet that 169 can be sent is built or there are no more sources, and then sends the 170 message. This process is repeated periodically within the SA- 171 Advertisement-Period in such a way that all of the RP's sources are 172 advertised. Note that the largest MSDP packet that can be sent has 173 size that is the minimum of MTU of outgoing link minus size of TCP 174 and IP headers, and 1400 (largest MSDP packet). Finally, the timer is 175 deleted when the MSDP process is deconfigured. 177 8.3. SA Cache Timeout (SA-State-Timer) 179 Each entry in an SA Cache has an associated SA-State-Timer. A 180 (S,G)-SA-State-Timer is started when an (S,G)-SA message is initially 181 received by a MSDP peer. The timer is reset to [SA-State-Period] if 182 another (S,G)-SA message is received before the (S,G)-SA-State-Timer 183 expires. [SA-State-Period] MUST NOT be less than 90 seconds. 185 8.4. SA-Hold-Down-Timer 187 The per-(S,G) timer is set to [SA-Hold-Down-Period] when forwarding 188 an SA message, and a SA message MUST only be forwarded when it's 189 associated timer is not running. [SA-Hold-Down-Period] SHOULD be set 190 to 30 seconds. A MSDP peer MUST NOT forward a (S,G)-SA message it has 191 received in during the previous [SA-Hold-Down-Period] seconds. 192 Finally, the timer is deleted when the SA cache entry is deleted. 194 8.5. KeepAlive Timer 196 The KeepAlive timer contols when to send MSDP KeepAlive messages. In 197 particular, the KeepAlive timer is used to reset the TCP connection 198 when the passive-connect side of the connection goes down. The 199 KeepAlive timer is set to [KeepAlive-Period] when the passive-connect 200 peer comes up. [KeepAlive-Period] SHOULD NOT be less that 75 seconds. 201 The timer is reset to [KeepAlive-Period] upon receipt of an MSDP 202 message from peer, and deleted when the timer expires or the 203 passive-connect peer closes the connection. 205 8.6. ConnectRetry Timer 207 The ConnectRetry timer is used by an MSDP peer to transition from 208 INACTIVE to CONNECTING states. There is one timer per peer, and the 209 [ConnectRetry-Period] SHOULD be set to 30 seconds. The timer is 210 initialized to [ConnectRetry-Period] when an MSDP peer's active 211 connect attempt fails. When the timer expires, the peer retries the 212 connection and the timer is reset to [ConnectRetry-Period]. It is 213 deleted if either the connection transitions into ESTABLISHED state 214 or the peer is deconfigured. 216 8.7. Peer Hold Timer 218 If a system does not receive successive KeepAlive messages (or any SA 219 message) within the period specified by the Hold Timer, then a 220 Notification message with Hold Timer Expired Error Code MUST be sent 221 and the MSDP connection MUST be closed. [Hold-Time-Period] MUST be at 222 least three seconds. A suggested value for [Hold-Time-Period] is 90 223 seconds. 225 The Hold Timer is initialized to [Hold-Time-Period] when the peer's 226 transport connection is established, and is reset to [Hold-Time- 227 Period] when any MSDP message is received. 229 9. Intermediate MSDP Peers 231 Intermediate RPs do not originate periodic SA messages on behalf of 232 sources in other domains. In general, an RP MUST only originate an SA 233 for a source which would register to it. 235 10. SA Filtering and Policy 237 As the number of (S,G) pairs increases in the Internet, an RP may 238 want to filter which sources it describes in SA messages. Also, 239 filtering may be used as a matter of policy which at the same time 240 can reduce state. Only the RP co-located in the same domain as the 241 source can restrict SA messages. Note, however, that MSDP peers in 242 transit domains should not filter SA messages or the flood-and-join 243 model can not guarantee that sources will be known throughout the 244 Internet (i.e., SA filtering by transit domains can cause undesired 245 lack of connectivity). In general, policy should be expressed using 246 MBGP [RFC2283]. This will cause MSDP messages to flow in the desired 247 direction and peer-RPF fail otherwise. An exception occurs at an 248 administrative scope [RFC2365] boundary. In particular, a SA message 249 for a (S,G) MUST NOT be sent to peers which are on the other side of 250 an administrative scope boundary for G. 252 11. SA Requests 254 A MSDP speaker MAY accept SA-Requests from other MSDP peers. When an 255 MSDP speaker receives an SA-Request for a group range, it will 256 respond to the peer with a set of SA entries, in an SA-Response 257 message, for all active sources sending to the group range requested 258 in the SA-Request message. The peer that sends the request will not 259 flood the responding SA-Response message to other peers. See section 260 17 for discussion of error handling relating to SA requests and 261 responses. 263 12. Encapsulated Data Packets 265 For bursty sources, the RP may encapsulate multicast data from the 266 source. An interested RP may decapsulate the packet, which SHOULD be 267 forwarded as if a PIM register encapsulated packet was received. That 268 is, if packets are already arriving over the interface toward the 269 source, then the packet is dropped. Otherwise, if the outgoing 270 interface list is non-null, the packet is forwarded appropriately. 271 Note that when doing data encapsulation, an implementation MUST bound 272 the time during which packets are encapsulated. 274 This allows for small bursts to be received before the multicast tree 275 is built back toward the source's domain. For example, an 276 implementation SHOULD encapsulate at least the first packet to 277 provide service to bursty sources. 279 13. Other Scenarios 281 MSDP is not limited to deployment across different routing domains. 282 It can be used within a routing domain when it is desired to deploy 283 multiple RPs for the same group ranges. As long as all RPs have a 284 interconnected MSDP topology, each can learn about active sources as 285 well as RPs in other domains. 287 14. MSDP Peer-RPF Forwarding 289 The MSDP Peer-RPF Forwarding rules are used for forwarding SA 290 messages throughout an MSDP enabled internet. Unlike the RPF check 291 used when forwarding data packets, the Peer-RPF check is against the 292 RP address carried in the SA message. 294 14.1. Peer-RPF Forwarding Rules 296 An SA message originated by R and received by X 297 from N is accepted if N is the peer-RPF neighbor for R, and is 298 discarded otherwise. 300 MP(R,N) MP(N,X) 301 R ---------....-------> N ------------------> X 302 SA(S,G,R) SA(S,G,R) 304 Where MP(A,B) is an MSDP peering path (one or more 305 MSDP peers) between A and B, and SA(S,G,R) is an 306 SA message for source S on group G orignated by 307 an RP R. 309 The peer-RPF neighbor is chosen deterministically, 310 using the first of the following rules that matches. 312 X accepts the SA from R forwarded by N if : 314 (i). R is the RPF neighbor if we have an MSDP peering 315 with R (e.g. N == R). 317 (ii). N is the RPF neighbor of X if N is a MSDP peer of 318 X and N is the next hop toward R. 320 (iii). N is the RPF neighbor of X if X has an MSDP 321 peering(s) with the neighboring AS (the AS 322 with that AS, then the MSDP neighbor with the 323 highest IP address in the first AS toward R is 324 the RPF peer. 326 (iv). N is the RPF neighbor of X if (intra-domain case): 328 (a). N == R (i.e. N originated the SA), or 330 (b). X and N are part of a MSDP Mesh Group. Note that in 331 this case every member of mesh group is an peer-RPF 332 neighbor of X. 334 (v). If none of the above match, and we have an 335 MSDP default-peer configured, the MSDP 336 default-peer is the RPF neighbor. 338 14.2. MSDP default-peer semantics 340 An MSDP default-peer is much like a default route. It is intended to 341 be used in those cases where a stub network isn't running BGP. An 342 MSDP peer configured with a default-peer accepts all SA messages from 343 the default-peer. Note that a router running BGP SHOULD NOT allow 344 configuration of default peers, since this allows the possibility for 345 SA looping or black-holes to occur. 347 14.3. MSDP mesh-group semantics 349 A MSDP mesh-group is a operational mechanism for reducing SA 350 flooding, typically in an intra-domain setting. In particular, when 351 some subset of a domain's MSDP speakers are fully meshed, then can be 352 configured into a mesh-group. The semantics of the mesh-group are as 353 follows: 355 (i). If a member R of a mesh-group M receives a SA message from an 356 MSDP peer that is also a member of mesh-group M, R accepts the 357 SA message and forwards it to all of it's peers that are not 358 part of any mesh-group. R MUST NOT forward the SA message to 359 other members of mesh-group M. 361 (ii). If a member R of a mesh-group M receives a SA message from an 362 MSDP peer that is not a member of mesh-group M, and the SA 363 message passes the peer-RPF check, then R forwards the SA 364 message to all members of mesh-group M. 366 Note that since mesh-groups suspend peer-RPF checking of SAs received 367 from a mesh-group member ((i). above), they allow for mis- 368 configuration to cause SA looping. 370 15. MSDP Connection Establishment 372 MSDP messages will be encapsulated in a TCP connection. An MSDP peer 373 listens for new TCP connections on port 639. One side of the MSDP 374 peering relationship will listen on the well-known port and the other 375 side will do an active connect to the well-known port. The side with 376 the higher peer IP address will do the listen. This connection 377 establishment algorithm avoids call collision. Therefore, there is no 378 need for a call collision procedure. It should be noted, however, 379 that the disadvantage of this approach is that it may result in 380 longer startup times at the passive end. 382 An MSDP peer starts in the INACTIVE state. MSDP peers establish 383 peering sessions according to the following state machine: 385 De-configured or 386 disabled 387 +-------------------------------------------+ 388 | | 389 | | 390 Enable | 391 +-----|--------->+----------+ Connect Retry Timer | 392 | | +->| INACTIVE |----------------+ | 393 | | | +----------+ | | 394 Deconf'ed | | | /|\ /|\ | | Lower Address 395 or | | | | | | | 396 disabled | | | | | \|/ | 397 | | | | | | +-------------+ 398 | | | | | +---------------| CONNECTING | 399 | | | | | Timeout or +-------------+ 400 | | | | | Local Address Change | 401 \|/ \|/ | | | | 402 +----------+ | | | | 403 | DISABLED | | | +---------------------+ | TCP Established 404 +----------+ | | | | 405 /|\ /|\ | | Connection Timeout, | | 406 | | | | Local Address change, | | 407 | | | | Authorization Failure | | 408 | | | | | | 409 | | | | | \|/ 410 | | | | +-------------+ 411 | | Local | | | ESTABLISHED | 412 | | Address | | Higher Address +-------------+ 413 | | Change | \|/ /|\ | 414 | | | +--------+ | | 415 | | +--| LISTEN |--------------------+ | 416 | | +--------+ TCP Accept | 417 | | | | 418 | | | | 419 | +---------------+ | 420 | De-configured or | 421 | disabled | 422 | | 423 +------------------------------------------------------+ 424 De-configured or 425 disabled 427 16. Packet Formats 429 MSDP messages will be encoded in TLV format. If an implementation 430 receives a TLV that has length that is longer than expected, the TLV 431 SHOULD be accepted. Any additional data SHOULD be ignored. 433 16.1. MSDP TLV format: 435 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 436 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 437 | Type | Length | Value .... | 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 440 Type (8 bits) 441 Describes the format of the Value field. 443 Length (16 bits) 444 Length of Type, Length, and Value fields in octets. 445 minimum length required is 4 octets, except for 446 Keepalive messages. 448 Value (variable length) 449 Format is based on the Type value. See below. The length of 450 the value field is Length field minus 3. All reserved fields 451 in the Value field MUST be transmitted as zeros and ignored on 452 receipt. 454 16.2. Defined TLVs 456 The following TLV Types are defined: 458 Code Type 459 =========================================================== 460 1 IPv4 Source-Active 461 2 IPv4 Source-Active Request 462 3 IPv4 Source-Active Response 463 4 KeepAlive 464 5 Notification 466 Each TLV is described below. 468 16.2.1. IPv4 Source-Active TLV 470 The maximum size SA message that can be sent is 1400 octets. If an 471 MSDP peer needs to originate a message with information greater than 472 1400 octets, it sends successive 1400 octet or smaller messages. The 473 1400 octet size does not include the TCP, IP, layer-2 headers. 475 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 | 1 | x + y | Entry Count | 478 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 479 | RP Address | 480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 481 | Reserved | Sprefix Len | \ 482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ 483 | Group Address | ) z 484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / 485 | Source Address | / 486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 488 Type 489 IPv4 Source-Active TLV is type 1. 491 Length x 492 Is the length of the control information in the message. x is 493 8 octets (for the first two 32-bit quantities) plus 12 times 494 Entry Count octets. 496 Length y 497 If 0, then there is no data encapsulated. Otherwise an IPv4 498 packet follows and y is the length of the total length field 499 of the IPv4 header encapsulated. If there are multiple SA TLVs 500 in a message, and data is also included, y must be 0 in all SA 501 TLVs except the last one and the last SA TLV must reflect the 502 source and destination addresses in the IP header of the 503 encapsulated data. 505 Entry Count 506 Is the count of z entries (note above) which follow the RP 507 address field. This is so multiple (S,G)s from the same domain 508 can be encoded efficiently for the same RP address. 510 RP Address 511 The address of the RP in the domain the source has become 512 active in. 514 Reserved 515 The Reserved field MUST be transmitted as zeros and ignored 516 by a receiver. 518 Sprefix Len 519 The route prefix length associated with source address. 520 This field MUST be transmitted as 32 (/32). An Invalid 521 Sprefix Len Notification SHOULD be sent upon receipt 522 of any other value. 524 Group Address 525 The group address the active source has sent data to. 527 Source Address 528 The IP address of the active source. 530 Multiple SA TLVs MAY appear in the same message and can be batched 531 for efficiency at the expense of data latency. This would typically 532 occur on intermediate forwarding of SA messages. 534 16.2.2. IPv4 Source-Active Request TLV 536 The Source-Active Request is used to request SA-state from a MSDP 537 peer. If an RP in a domain receives a PIM Join message for a group, 538 creates (*,G) state and wants to know all active sources for group G, 539 it may send an SA-Request message for the group. 541 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 543 | 2 | 8 | Reserved | 544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 545 | Group Address Prefix | 546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 548 Type 549 IPv4 Source-Active Request TLV is type 2. 551 Reserved 552 Must be transmitted as zero and ignored on receipt. 554 Group Address 555 The group address the MSDP peer is requesting. 557 16.2.3. IPv4 Source-Active Response TLV 559 The Source-Active Response is sent in response to a Source-Active 560 Request message. The Source-Active Response message has the same 561 format as a Source-Active message but does not allow encapsulation of 562 multicast data. 564 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 565 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 566 | 3 | x | .... | 567 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 569 Type 570 IPv4 Source-Active Response TLV is type 3. 572 Length x 573 Is the length of the control information in the message. x is 8 574 octets (for the first two 32-bit quantities) plus 12 times Entry 575 Count octets. 577 16.2.4. KeepAlive TLV 579 A KeepAlive TLV is sent to an MSDP peer if and only if there were no 580 MSDP messages sent to the peer after a period of time. This message 581 is necessary for the active connect side of the MSDP connection. The 582 passive connect side of the connection knows that the connection will 583 be reestablished when a TCP SYN packet is sent from the active 584 connect side. However, the active connect side will not know when the 585 passive connect side goes down. Therefore, the KeepAlive timeout will 586 be used to reset the TCP connection. 588 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 590 | 4 | 3 | 591 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 593 The length of the message is 3 octets which encompasses the one octet 594 Type field and the two octet Length field. 596 16.2.5. Notification TLV 598 A Notification message is sent when an error condition is detected, 599 and has the following form: 601 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 602 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 603 | 5 | x + 5 |O| Error Code | 604 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 605 | Error subcode | ... | 606 +-+-+-+-+-+-+-+-+ | 607 | Data | 608 | ... | 609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 611 Type 612 The Notification TLV is type 5. 614 Length 615 Length is a two octet field with value x + 5, where x is 616 the length of the notification data field. 618 O-bit 619 Open-bit. If clear, the connection will be closed. 621 Error code 622 This 7-bit unsigned integer indicates the type of Notification. 623 The following Error Codes have been defined: 625 Error Code Symbolic Name Reference 627 1 Message Header Error Section 17.1 628 2 SA-Request Error Section 17.2 629 3 SA-Message/SA-Response Error Section 17.3 630 4 Hold Timer Expired Section 17.4 631 5 Finite State Machine Error Section 17.5 632 6 Notification Section 17.6 633 7 Cease Section 17.7 635 Error subcode: 636 This one-octet unsigned integer provides more specific information 637 about the reported error. Each Error Code may have one or more Error 638 Subcodes associated with it. If no appropriate Error Subcode is 639 defined, then a zero (Unspecific) value is used for the Error Subcode 640 field, and the O-bit must be cleared (i.e. the connection will be 641 closed). The used notation in the error description below is: MC = 642 Must Close connection = O-bit clear; CC = Can Close connection = 643 O-bit might be cleared. 645 Message Header Error subcodes: 647 0 - Unspecific (MC) 648 2 - Bad Message Length (MC) 649 3 - Bad Message Type (CC) 651 SA-Request Error subcodes: 653 0 - Unspecific (MC) 654 1 - Invalid Group (MC) 656 SA-Message/SA-Response Error subcodes 658 0 - Unspecific (MC) 659 1 - Invalid Entry Count (CC) 660 2 - Invalid RP Address (MC) 661 3 - Invalid Group Address (MC) 662 4 - Invalid Source Address (MC) 663 5 - Invalid Sprefix Length (MC) 664 6 - Looping SA (Self is RP) (MC) 665 7 - Unknown Encapsulation (MC) 666 8 - Administrative Scope Boundary Violated (MC) 668 Hold Timer Expired subcodes (the O-bit is always clear): 670 0 - Unspecific (MC) 672 Finite State Machine Error subcodes: 674 0 - Unspecific (MC) 675 1 - Unexpected Message Type FSM Error (MC) 677 Notification subcodes (the O-bit is always clear): 679 0 - Unspecific (MC) 681 Cease subcodes (the O-bit is always clear): 683 0 - Unspecific (MC) 685 17. MSDP Error Handling 687 This section describes actions to be taken when errors are detected 688 while processing MSDP messages. MSDP Error Handling is similar to 689 that of BGP [RFC1771]. 691 When any of the conditions described here are detected, a 692 Notification message with the indicated Error Code, Error Subcode, 693 and Data fields is sent. In addition, the MSDP connection might be 694 closed. If no Error Subcode is specified, then a zero (Unspecific) 695 must be used. 697 The phrase "the MSDP connection is closed" means that the transport 698 protocol connection has been closed and that all resources for that 699 MSDP connection have been deallocated. 701 17.1. Message Header Error Handling 703 All errors detected while processing the Message Header are indicated 704 by sending the Notification message with Error Code Message Header 705 Error. The Error Subcode describes the specific nature of the error. 706 The Data field contains the erroneous Message (including the message 707 header). 709 If the Length field of the message header is less than 4 or greater 710 than 1400, or the length of a KeepAlive message is not equal to 3, 711 then the Error Subcode is set to Bad Message Length. 713 If the Type field of the message header is not recognized, then the 714 Error Subcode is set to Bad Message Type. 716 17.2. SA-Request Error Handling 718 The SA-Request Error code is used to signal the receipt of a SA 719 request at a MSDP peer when an invalid group address requested. 721 When a MSDP peer receives a request for an invalid group, it returns 722 the following notification: 724 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 725 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 726 | 5 | 16 |O| 2 | 727 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 728 | 2 | Reserved | Gprefix Len | 729 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 730 | Gprefix | 731 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 732 | Invalid Group Address | 733 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 735 17.3. SA-Message/SA-Response Error Handling 737 The SA-Message/SA-Response Error code is used to signal the receipt 738 of a erroneous SA Message at an MSDP peer, or the receipt of an SA- 739 Response Message by a peer that did not issue a SA-Request. It has 740 the following form: 742 17.3.1. Invalid Entry Count (IEC) 744 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 745 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 746 | 5 | 6 |O| 3 | 747 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 748 | 1 | IEC | 749 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 751 17.3.2. Invalid RP Address 753 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 754 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 755 | 5 | 12 |O| 3 | 756 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 757 | 2 | Reserved | 758 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 759 | Invalid RP Address | 760 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 762 17.3.3. Invalid Group Address 764 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 765 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 766 | 5 | 12 |O| 3 | 767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 768 | 3 | Reserved | 769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 770 | Invalid Group Address | 771 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 773 17.3.4. Invalid Source Address 775 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 776 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 777 | 5 | 12 |O| 3 | 778 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 779 | 4 | Reserved | 780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 781 | Invalid Source Address | 782 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 784 17.3.5. Invalid Sprefix Length (ISL) 786 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 787 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 788 | 5 | 6 |O| 3 | 789 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 790 | 5 | ISL | 791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 793 17.3.6. Looping SAs (Self is RP in received SA) 795 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 796 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 797 | 5 | x + 5 |O| 3 | 798 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 799 | 6 | Looping SA Message .... 800 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 802 Length x 803 x is the length of the looping SA message contained in the data 804 field of the Notification message. 806 17.3.7. Unknown Encapsulation 808 This notification is sent on receipt of SA data that is encapsulated 809 in an unknown encapsulation type. See section 18 for known 810 encapsulations. 812 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 813 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 814 | 5 | x + 5 |O| 3 | 815 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 816 | 7 | SA Message .... 817 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 818 Length x 819 x is the length of the SA message (which contained data which 820 was encapsulated in some unknown way) that is contained in the 821 data field of the Notification message. 823 17.3.8. Administrative Scope Boundary Violated 825 This notification is used when an SA message is received for a group 826 G from a peer which is across an administrative scope boundary for G. 828 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 829 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 830 | 5 | 16 |O| 3 | 831 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 832 | 8 | Reserved | Gprefix Len | 833 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 834 | Gprefix | 835 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 836 | Group Address | 837 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 839 17.4. Hold Time Expired 841 If a system does not receive successive KeepAlive or any SA Message 842 and/or Notification messages within the period specified in the Hold 843 Timer, the notification message with Hold Timer Expired Error Code 844 and no additional data MUST be sent and the MSDP connection closed. 846 17.5. Finite State Machine Error Handling 848 Any error detected by the MSDP Finite State Machine (e.g., receipt of 849 an unexpected event) is indicated by sending the Notification message 850 with Error Code Finite State Machine Error. 852 17.6. Notification Message Error Handling 854 If a node sends a Notification message, and there is an error in that 855 message, and the O-bit of that message is not clear, a Notification 856 with O-bit clear, Error Code of Notification Error, and subcode 857 Unspecific must be sent. In addition, the Data field must include 858 the Notification message that triggered the error. However, if the 859 erroneous Notification message had the O-bit clear, then any error, 860 such as an unrecognized Error Code or Error Subcode, should be 861 noticed, logged locally, and brought to the attention of the 862 administrator of the remote node. 864 17.7. Cease 866 In absence of any fatal errors (that are indicated in this section), 867 an MSDP node may choose at any given time to close its MSDP 868 connection by sending the Notification message with Error Code Cease. 869 However, the Cease Notification message MUST NOT be used when a fatal 870 error indicated by this section does exist. 872 18. SA Data Encapsulation 874 This section describes UDP, GRE, and TCP encapsulation of SA data. 875 Encapsulation type is a configuration option. 877 18.1. UDP Data Encapsulation 879 Data packets MAY be encapsulated in UDP. In this case, the UDP 880 pseudo-header has the following form: 882 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 883 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 884 | Source Port | Destination Port | 885 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 886 | Length | Checksum | 887 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 888 | Origin RP Address | 889 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 891 The Source port, Destination Port, Length, and Checksum are used 892 according to RFC 768. Source and Destination ports are known via an 893 implementation-specific method (e.g. per-peer configuration). 895 Checksum 896 The checksum is computed according to RFC 768 [RFC768]. 898 Originating RP Address 899 The Originating RP Address is the address of the RP sending 900 the encapsulated data. 902 18.2. GRE Encapsulation 904 MSDP SA-data MAY be encapsulated in GRE using protocol type [MSDP- 905 GRE-ProtocolType]. The GRE header and payload packet have the 906 following form: 908 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 909 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 910 |C| Reserved0 | Ver | [MSDP-GRE-ProtocolType] |\ 911 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ GRE Header 912 | Checksum (optional) | Reserved1 |/ 913 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 914 | Originating RP IPv4 Address |\ 915 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Payload 916 | (S,G) Data Packet .... / 917 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 919 18.2.1. Encapsulation and Path MTU Discovery [RFC1191] 921 Existing implementations of GRE, when using IPv4 as the Delivery 922 Header, do not implement Path MTU discovery and do not set the Don't 923 Fragment bit in the Delivery Header. This can cause large packets to 924 become fragmented within the tunnel and reassembled at the tunnel 925 exit (independent of whether the payload packet is using PMTU). If a 926 tunnel entry point were to use Path MTU discovery, however, that 927 tunnel entry point would also need to relay ICMP unreachable error 928 messages (in particular the "fragmentation needed and DF set" code) 929 back to the originator of the packet, which is not required by the 930 GRE specification [RFC2784]. Failure to properly relay Path MTU 931 information to an originator can result in the following behavior: 932 the originator sets the don't fragment bit, the packet gets dropped 933 within the tunnel, but since the originator doesn't receive proper 934 feedback, it retransmits with the same PMTU, causing subsequently 935 transmitted packets to be dropped. 937 18.3. TCP Data Encapsulation 939 As discussed earlier, encapsulation of data in SA messages MAY be 940 supported for backwards compatibility with legacy MSDP peers. 942 19. IANA Considerations 944 The IANA should assigne 0x0009 from the IANA SNAP Protocol IDs [IANA] 945 to MSDP-GRE-ProtocolType. 947 20. Security Considerations 949 An MSDP implementation MAY use IPsec [RFC1825] or keyed MD5 [RFC1828] 950 to secure control messages. When encapsulating SA data in GRE, 951 security should be relatively similar to security in a normal IPv4 952 network, as routing using GRE follows the same routing that IPv4 uses 953 natively. Route filtering will remain unchanged. However packet 954 filtering at a firewall requires either that a firewall look inside 955 the GRE packet or that the filtering is done on the GRE tunnel 956 endpoints. In those environments in which this is considered to be a 957 security issue it may be desirable to terminate the tunnel at the 958 firewall. 960 21. Acknowledgments 962 The editor would like to thank the original authors, Dino Farinacci, 963 Yakov Rehkter, Peter Lothberg, Hank Kilmer, and Jermey Hall for their 964 orginal contribution to the MSDP specification. In addition, Bill 965 Nickless, John Meylor, Liming Wei, Manoj Leelanivas, Mark Turner, 966 John Zwiebel, Cristina Radulescu-Banu and IJsbrand Wijnands provided 967 useful and productive design feedback and comments. In addition to 968 many other contributions, Tom Pusateri helped to clarify the 969 connection state machine, Dave Thaler helped to clarify the 970 Notification message types, and Bill Fenner helped to clarify the 971 Peer-RPF rules. 973 22. Editor's Address: 975 David Meyer 976 Cisco Systems, Inc. 977 170 Tasman Drive 978 San Jose, CA, 95134 979 Email: dmm@cisco.com 981 23. REFERENCES 983 [IANA] ftp://www.iana.org 985 [RFC1700] J. Reynolds and J. Postel, "Assigned Numbers", RFC 1700, 986 October, 1994. 988 [RFC2784] Farinacci, D., et al., "Generic Routing Encapsulation 989 (GRE)", RFC 2784, March 2000. 991 [RFC768] Postel, J. "User Datagram Protocol", RFC 768, August, 992 1980. 994 [RFC1191] Mogul, J., and S. Deering, "Path MTU Discovery", 995 RFC 1191, November 1990. 997 [RFC1771] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4 998 (BGP-4)", RFC 1771, March 1995. 1000 [RFC1825] Atkinson, R., "Security Architecture for the Internet 1001 Protocol", RFC 1825, August, 1995. 1003 [RFC1828] P. Metzger and W. Simpson, "IP Authentication using 1004 Keyed MD5", RFC 1828, August, 1995. 1006 [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate 1007 Requirement Levels", RFC 2119, March, 1997. 1009 [RFC2283] Bates, T., Chandra, R., Katz, D., and Y. Rekhter., 1010 "Multiprotocol Extensions for BGP-4", RFC 2283, 1011 February 1998. 1013 [RFC2362] Estrin D., et al., "Protocol Independent Multicast - 1014 Sparse Mode (PIM-SM): Protocol Specification", RFC 1015 2362, June 1998. 1017 [RFC2365] Meyer, D. "Administratively Scoped IP Multicast", RFC 1018 2365, July, 1998.