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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MULTIMOB Group T C. Schmidt, Ed. 3 Internet-Draft HAW Hamburg 4 Intended status: Standards Track S. Gao 5 Expires: August 29, 2013 H. Zhang 6 Beijing Jiaotong University 7 M. Waehlisch 8 link-lab & FU Berlin 9 February 25, 2013 11 Mobile Multicast Sender Support in Proxy Mobile IPv6 (PMIPv6) Domains 12 draft-ietf-multimob-pmipv6-source-03 14 Abstract 16 Multicast communication can be enabled in Proxy Mobile IPv6 domains 17 via the Local Mobility Anchors by deploying MLD Proxy functions at 18 Mobile Access Gateways, via a direct traffic distribution within an 19 ISP's access network, or by selective route optimization schemes. 20 This document describes the support of mobile multicast senders in 21 Proxy Mobile IPv6 domains for all three scenarios. Protocol 22 optimizations for synchronizing PMIPv6 with PIM, as well as extended 23 MLD Proxy functions are presented. Mobile sources always remain 24 agnostic of multicast mobility operations. 26 Requirements Language 28 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 29 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 30 document are to be interpreted as described in RFC 2119 [RFC2119]. 32 Status of this Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at http://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on August 29, 2013. 49 Copyright Notice 51 Copyright (c) 2013 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (http://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 68 3. Base Solution for Source Mobility and PMIPv6 Routing . . . . . 5 69 3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 5 70 3.2. Base Solution for Source Mobility: Details . . . . . . . . 9 71 3.2.1. Operations of the Mobile Node . . . . . . . . . . . . 9 72 3.2.2. Operations of the Mobile Access Gateway . . . . . . . 9 73 3.2.3. Operations of the Local Mobility Anchor . . . . . . . 9 74 3.2.4. IPv4 Support . . . . . . . . . . . . . . . . . . . . . 10 75 3.2.5. Efficiency of the Distribution System . . . . . . . . 11 76 4. Direct Multicast Routing . . . . . . . . . . . . . . . . . . . 11 77 4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 12 78 4.2. MLD Proxies at MAGs . . . . . . . . . . . . . . . . . . . 13 79 4.2.1. Considerations for PIM-SM on the Upstream . . . . . . 14 80 4.2.2. SSM Considerations . . . . . . . . . . . . . . . . . . 14 81 4.3. PIM-SM . . . . . . . . . . . . . . . . . . . . . . . . . . 14 82 4.3.1. Routing Information Base for PIM-SM . . . . . . . . . 14 83 4.3.2. Operations of PIM in Phase One . . . . . . . . . . . . 15 84 4.3.3. Operations of PIM in Phase Two . . . . . . . . . . . . 16 85 4.3.4. Operations of PIM in Phase Three . . . . . . . . . . . 16 86 4.3.5. PIM-SSM Considerations . . . . . . . . . . . . . . . . 17 87 4.3.6. Handover Optimizations for PIM . . . . . . . . . . . . 17 88 4.4. BIDIR-PIM . . . . . . . . . . . . . . . . . . . . . . . . 18 89 4.4.1. Routing Information Base for BIDIR-PIM . . . . . . . . 18 90 4.4.2. Operations of BIDIR-PIM . . . . . . . . . . . . . . . 18 91 5. Extended MLD Proxy Function for Optimized Source Mobility 92 in PMIPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . 19 93 5.1. Peering Function for MLD Proxies . . . . . . . . . . . . . 19 94 5.1.1. Operations at the Multicast Sender . . . . . . . . . . 19 95 5.1.2. Operations at the Multicast Listener . . . . . . . . . 20 96 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 97 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21 98 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22 99 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 100 9.1. Normative References . . . . . . . . . . . . . . . . . . . 22 101 9.2. Informative References . . . . . . . . . . . . . . . . . . 23 102 Appendix A. Multiple Upstream Interface Proxy . . . . . . . . . . 23 103 A.1. Operations for Local Multicast Sources . . . . . . . . . . 24 104 A.2. Operations for Local Multicast Subscribers . . . . . . . . 24 105 Appendix B. Evaluation of Traffic Flows . . . . . . . . . . . . . 24 106 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 25 107 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26 109 1. Introduction 111 Proxy Mobile IPv6 (PMIPv6) [RFC5213] extends Mobile IPv6 (MIPv6) 112 [RFC6275] by network-based management functions that enable IP 113 mobility for a host without requiring its participation in any 114 mobility-related signaling. Additional network entities called the 115 Local Mobility Anchor (LMA), and Mobile Access Gateways (MAGs), are 116 responsible for managing IP mobility on behalf of the mobile node 117 (MN). An MN connected to a PMIPv6 domain, which only operates 118 according to the base specifications of [RFC5213], cannot participate 119 in multicast communication, as MAGs will discard group packets. 121 Multicast support for mobile listeners can be enabled within a PMIPv6 122 domain by deploying MLD Proxy functions at Mobile Access Gateways, 123 and multicast routing functions at Local Mobility Anchors [RFC6224]. 124 This base deployment option is the simplest way to PMIPv6 multicast 125 extensions in the sense that it follows the common PMIPv6 traffic 126 model and neither requires new protocol operations nor additional 127 infrastructure entities. Standard software functions need to be 128 activated on PMIPv6 entities, only, at the price of possibly non- 129 optimal multicast routing. 131 Alternate solutions leverage performance optimization by providing 132 multicast routing at the access gateways directly, or by selective 133 route optimization schemes. Such approaches (partially) follow the 134 business model of providing multicast data services in parallel to 135 PMIPv6 unicast routing. 137 Multicast listener support satisfies the needs of receptive use cases 138 such as IPTV or server-centric gaming on mobiles. However, current 139 trends in the Internet enfold towards user-centric, highly 140 interactive group applications like user generated streaming, 141 conferencing, collective mobile sensing, etc. Many of these popular 142 applications create group content at end systems and can largely 143 profit from a direct data transmission to a multicast-enabled 144 network. 146 This document describes the support of mobile multicast senders in 147 Proxy Mobile IPv6 domains subsequently for the base deployment 148 scenario [RFC6224], for direct traffic distribution within an ISP's 149 access network, as well as for selective route optimization schemes. 150 The contribution of this work reflects the source mobility problem as 151 discussed in [RFC5757]. Mobile Nodes in this setting remain agnostic 152 of multicast mobility operations. 154 2. Terminology 156 This document uses the terminology as defined for the mobility 157 protocols [RFC6275], [RFC5213] and [RFC5844], as well as the 158 multicast edge related protocols [RFC3376], [RFC3810] and [RFC4605]. 160 3. Base Solution for Source Mobility and PMIPv6 Routing 162 3.1. Overview 164 The reference scenario for multicast deployment in Proxy Mobile IPv6 165 domains is illustrated in Figure 1. MAGs play the role of first-hop 166 access routers that serve multiple MNs on the downstream while 167 running an MLD/IGMP proxy instance for every LMA upstream tunnel. 169 +-------------+ 170 | Multicast | 171 | Listeners | 172 +-------------+ 173 | 174 *** *** *** *** 175 * ** ** ** * 176 * * 177 * Fixed Internet * 178 * * 179 * ** ** ** * 180 *** *** *** *** 181 / \ 182 +----+ +----+ 183 |LMA1| |LMA2| Multicast Anchor 184 +----+ +----+ 185 LMAA1 | | LMAA2 186 | | 187 \\ //\\ 188 \\ // \\ 189 \\ // \\ Unicast Tunnel 190 \\ // \\ 191 \\ // \\ 192 \\ // \\ 193 Proxy-CoA1 || || Proxy-CoA2 194 +----+ +----+ 195 |MAG1| |MAG2| MLD Proxy 196 +----+ +----+ 197 | | | 198 MN-HNP1 | | MN-HNP2 | MN-HNP3 199 | | | 200 MN1 MN2 MN3 202 Multicast Sender + Listener(s) 204 Figure 1: Reference Network for Multicast Deployment in PMIPv6 with 205 Source Mobility 207 An MN in a PMIPv6 domain will decide on multicast data transmission 208 completely independent of its current mobility conditions. It will 209 send packets as initiated by applications, using its source address 210 with Home Network Prefix (HNP) and a multicast destination address 211 chosen by application needs. Multicast packets will arrive at the 212 currently active MAG via one of its downstream local (wireless) 213 links. A multicast unaware MAG would simply discard these packets in 214 the absence of a multicast routing information base (MRIB). 216 An MN can successfully distribute multicast data in PMIPv6, if MLD 217 proxy functions are deployed at the MAG as described in [RFC6224]. 218 In this set-up, the MLD proxy instance serving a mobile multicast 219 source has configured its upstream interface at the tunnel towards 220 MN's corresponding LMA. For each LMA, there will be a separate 221 instance of an MLD proxy. 223 According to the specifications given in [RFC4605], multicast data 224 arriving from a downstream interface of an MLD proxy will be 225 forwarded to the upstream interface and to all but the incoming 226 downstream interfaces that have appropriate forwarding states for 227 this group. Thus multicast streams originating from an MN will 228 arrive at the corresponding LMA and directly at all mobile receivers 229 co-located at the same MAG and MLD Proxy instance. Serving as the 230 designated multicast router or an additional MLD proxy, the LMA 231 forwards data to the fixed Internet, whenever forwarding states are 232 maintained by multicast routing. If the LMA is acting as another MLD 233 proxy, it will forward the multicast data to its upstream interface, 234 and to downstream interfaces with matching subscriptions, 235 accordingly. 237 In case of a handover, the MN (unaware of IP mobility) can continue 238 to send multicast packets as soon as network connectivity is 239 reconfigured. At this time, the MAG has determined the corresponding 240 LMA, and IPv6 unicast address configuration (including PMIPv6 241 bindings) has been performed. Still multicast packets arriving at 242 the MAG are discarded (if not buffered) until the MAG has completed 243 the following steps. 245 1. The MAG has determined that the MN is admissible to multicast 246 services. 248 2. The MAG has added the new downstream link to the MLD proxy 249 instance with up-link to the corresponding LMA. 251 As soon as the MN's uplink is associated with the corresponding MLD 252 proxy instance, multicast packets are forwarded again to the LMA and 253 eventually to receivers within the PMIP domain (see the call flow in 254 Figure 2). In this way, multicast source mobility is transparently 255 enabled in PMIPv6 domains that deploy the base scenario for 256 multicast. 258 MN1 MAG1 MN2 MAG2 LMA 259 | | | | | 260 | | Mcast Data | | | 261 | |<---------------+ | | 262 | | Mcast Data | | | 263 | Join(G) +================================================>| 264 +--------------> | | | | 265 | Mcast Data | | | | 266 |<---------------+ | | | 267 | | | | | 268 | < Movement of MN 2 to MAG2 & PMIP Binding Update > | 269 | | | | | 270 | | |--- Rtr Sol -->| | 271 | | |<-- Rtr Adv ---| | 272 | | | | | 273 | | | < MLD Proxy Configuration > | 274 | | | | | 275 | | | (MLD Query) | | 276 | | |<--------------+ | 277 | | | Mcast Data | | 278 | | +-------------->| | 279 | | | | Mcast Data | 280 | | | +===============>| 281 | | | | | 282 | | Mcast Data | | | 283 | |<================================================+ 284 | Mcast Data | | | | 285 |<---------------+ | | | 286 | | | | | 288 Figure 2: Call Flow for Group Communication in Multicast-enabled PMIP 290 These multicast deployment considerations likewise apply for mobile 291 nodes that operate with their IPv4 stack enabled in a PMIPv6 domain. 292 PMIPv6 can provide IPv4 home address mobility support [RFC5844]. 293 IPv4 multicast is handled by an IGMP proxy function at the MAG in an 294 analogous way. 296 Following these deployment steps, multicast traffic distribution 297 transparently inter-operates with PMIPv6. It is worth noting that an 298 MN - while being attached to the same MAG as the mobile source, but 299 associated with a different LMA - cannot receive multicast traffic on 300 a shortest path. Instead, multicast streams flow up to the LMA of 301 the mobile source, are transferred to the LMA of the mobile listener 302 and tunneled downwards to the MAG again (see Appendix B for further 303 considerations). 305 3.2. Base Solution for Source Mobility: Details 307 Incorporating multicast source mobility in PMIPv6 requires to deploy 308 general multicast functions at PMIPv6 routers and to define their 309 interaction with the PMIPv6 protocol in the following way. 311 3.2.1. Operations of the Mobile Node 313 A Mobile Node willing to send multicast data will proceed as if 314 attached to the fixed Internet. No specific mobility or other 315 multicast related functionalities are required at the MN. 317 3.2.2. Operations of the Mobile Access Gateway 319 A Mobile Access Gateway is required to have MLD proxy instances 320 deployed, one for each tunnel to an LMA, which serves as its unique 321 upstream link (cf., [RFC6224]). On the arrival of an MN, the MAG 322 decides on the mapping of downstream links to a proxy instance and 323 the upstream link to the LMA based on the regular Binding Update List 324 as maintained by PMIPv6 standard operations. When multicast data is 325 received from the MN, the MAG MUST identify the corresponding proxy 326 instance from the incoming interface and forwards multicast data 327 upstream according to [RFC4605]. 329 The MAG MAY apply special admission control to enable multicast data 330 transition from an MN. It is advisable to take special care that MLD 331 proxy implementations do not redistribute multicast data to 332 downstream interfaces without appropriate subscriptions in place. 334 3.2.3. Operations of the Local Mobility Anchor 336 For any MN, the Local Mobility Anchor acts as the persistent Home 337 Agent and at the same time as the default multicast upstream for the 338 corresponding MAG. It will manage and maintain a multicast 339 forwarding information base for all group traffic arriving from its 340 mobile sources. It SHOULD participate in multicast routing functions 341 that enable traffic redistribution to all adjacent LMAs within the 342 PMIPv6 domain and thereby ensure a continuous receptivity while the 343 source is in motion. 345 3.2.3.1. Local Mobility Anchors Operating PIM 347 Local Mobility Anchors that operate the PIM-SM routing protocol 348 [RFC4601] will require sources to be directly connected for sending 349 PIM registers to the RP. This does not hold in a PMIPv6 domain, as 350 MAGs are routers intermediate to MN and the LMA. In this sense, MNs 351 are multicast sources external to the PIM-SM domain. 353 To mitigate this incompatibility common to all subsidiary MLD proxy 354 domains, the LMA should act as a PIM Border Router and activate the 355 Border-bit. In this case, the DirectlyConnected(S) is treated as 356 being TRUE for mobile sources and the PIM-SM forwarding rule "iif == 357 RPF_interface(S)" is relaxed to be TRUE, as the incoming tunnel 358 interface from MAG to LMA is considered as not part of the PIM-SM 359 component of the LMA (see A.1 of [RFC4601] ). 361 In addition, an LMA serving as PIM Designated Router is connected to 362 MLD proxies via individual IP-tunnel interfaces and will experience 363 changing PIM source states on handover. As the incoming interface 364 connects to a point-to-point link, PIM Assert contention is not 365 active, and incoming interface validation is only performed by RPF 366 checks. Consequently, a PIM DR should update incoming source states, 367 as soon as RPF inspection succeeds, i.e., after PMIPv6 forwarding 368 state update. Consequently, PIM routers SHOULD be able to manage 369 these state changes, but some implementations are expected to 370 incorrectly refuse packets until the previous state has timed out. 372 Notably, running BIDIR PIM [RFC5015] on LMAs remains robust with 373 respect to source location and does not require special 374 configurations or state management for sources. 376 3.2.4. IPv4 Support 378 An MN in a PMIPv6 domain may use an IPv4 address transparently for 379 communication as specified in [RFC5844]. For this purpose, an LMA 380 can register an IPv4-Proxy-CoA in its Binding Cache and the MAG can 381 provide IPv4 support in its access network. Correspondingly, 382 multicast membership management will be performed by the MN using 383 IGMP. For multicast support on the network side, an IGMP proxy 384 function needs to be deployed at MAGs in exactly the same way as for 385 IPv6. [RFC4605] defines IGMP proxy behaviour in full agreement with 386 IPv6/MLD. Thus IPv4 support can be transparently provided following 387 the obvious deployment analogy. 389 For a dual-stack IPv4/IPv6 access network, the MAG proxy instances 390 SHOULD choose multicast signaling according to address configurations 391 on the link, but MAY submit IGMP and MLD queries in parallel, if 392 needed. It should further be noted that the infrastructure cannot 393 identify two data streams as identical when distributed via an IPv4 394 and IPv6 multicast group. Thus duplicate data may be forwarded on a 395 heterogeneous network layer. 397 A particular note is worth giving the scenario of [RFC5845] in which 398 overlapping private address spaces of different operators can be 399 hosted in a PMIP domain by using GRE encapsulation with key 400 identification. This scenario implies that unicast communication in 401 the MAG-LMA tunnel can be individually identified per MN by the GRE 402 keys. This scenario still does not impose any special treatment of 403 multicast communication for the following reasons. 405 Multicast streams from and to MNs arrive at a MAG on point-to-point 406 links (identical to unicast). Multicast data transmission from the 407 MAG to the corresponding LMA is link-local between the routers and 408 routing/forwarding remains independent of any individual MN. So the 409 MAG-proxy and the LMA SHOULD NOT use GRE key identifiers, but plain 410 GRE encapsulation in multicast communication (including MLD queries 411 and reports). Multicast traffic sent upstream and downstream of MAG- 412 to-LMA tunnels proceeds as router-to-router forwarding according to 413 the multicast routing information base (MRIB) of the MAG or LMA and 414 independent of MN's unicast addresses, while the MAG proxy instance 415 re-distributes multicast data down the point-to-point links 416 (interfaces) according to its own MRIB, independent of MN's IP 417 addresses. 419 3.2.5. Efficiency of the Distribution System 421 The distribution system of the base solution directly follows PMIPv6 422 routing rules, and organizes multicast domains with respect to LMAs. 423 Thus, no coordination between address spaces or services is required 424 between the different instances, provided their associated LMAs 425 belong to disjoint multicast domains. Routing is optimal for 426 communication between MNs of the same domain, or stationary 427 subscribers. 429 In the following efficiency-related issues remain. 431 Multicast reception at LMA In the current deployment scenario, the 432 LMA will receive all multicast traffic originating from its 433 associated MNs. There is no mechanism to suppress upstream 434 forwarding in the absence of receivers. 436 MNs on the same MAG using different LMAs For a mobile receiver and a 437 source that use different LMAs, the traffic has to go up to one 438 LMA, cross over to the other LMA, and then be tunneled back to the 439 same MAG, causing redundant flows in the access network and at the 440 MAG. 442 4. Direct Multicast Routing 444 There are deployment scenarios, where multicast services are 445 available throughout the access network independent of the PMIPv6 446 routing system [I-D.ietf-multimob-pmipv6-ropt]. In these cases, the 447 visited networks grant a local content distribution service (in 448 contrast to LMA-based home subscription) with locally optimized 449 traffic flows. It is also possible to deploy a mixed service model 450 of local and LMA-based subscriptions, provided a unique way of 451 service selection is implemented. For example, access routers (MAGs) 452 could decide on service access based on the multicast address G or 453 the SSM channel (S,G) under request (see Section 5 for a further 454 discussion). 456 4.1. Overview 458 Direct multicast access can be supported by 460 o native multicast routing provided by one multicast router that is 461 neighboring MLD proxies deployed at MAGs within a flat access 462 network, or via tunnel uplinks, 464 o a multicast routing protocol such as PIM-SM [RFC4601] or BIDIR-PIM 465 [RFC5015] deployed at the MAGs. 467 *** *** *** *** 468 * ** ** ** * 469 * * 470 * Multicast * 471 +----+ * Infrastructure * +----+ 472 |LMA | * ** ** ** * |LMA | 473 +----+ *** *** *** *** +----+ 474 | // \\ | 475 \\ // \\ PMIP (unicast) | 476 PMIP \\ // \\ // \\ ** *** *** ** // 477 (unicast) \\ // \\ // \\ * ** ** ** // 478 \\ // \\ // \\* Multicast *// 479 || || || || * || Routing || * 480 +----+ +----+ * +----+ +----+ * 481 MLD Proxy |MAG1| |MAG2| * |MAG1| |MAG2| * 482 +----+ +----+ *+----+ ** ** +----+* 483 | | | | |*** *** ***| 484 | | | | | | 485 MN1 MN2 MN3 MN1 MN2 MN3 487 (a) Multicast Access at Proxy Uplink (b) Multicast Routing at MAG 489 Figure 3: Reference Networks for (a) Proxy-assisted Direct Multicast 490 Access and (b) Dynamic Multicast Routing at MAGs 492 Figure 3 displays the corresponding deployment scenarios, which 493 separate multicast from PMIPv6 unicast routing. It is assumed 494 throughout these scenarios that all MAGs (MLD proxies) are linked to 495 a single multicast routing domain. Noteworthy, this scenario 496 requires coordination of multicast address utilization and service 497 bindings. 499 Multicast traffic distribution can be simplified in these scenarios. 500 A single proxy instance at MAGs with up-link into the multicast 501 domain will serve as a first hop multicast gateway and avoid traffic 502 duplication or detour routing. Multicast routing functions at MAGs 503 will seamlessly embed access gateways within a multicast cloud. 504 However, mobility of the multicast source in this scenario will 505 require some multicast routing protocols to rebuild distribution 506 trees. This can cause significant service disruptions or delays (see 507 [RFC5757] for further aspects). Deployment details are specific to 508 the multicast routing protocol in use, in the following described for 509 common protocols. 511 4.2. MLD Proxies at MAGs 513 In a PMIPv6 domain, single MLD proxy instances can be deployed at 514 each MAG that enable multicast service at the access via an uplink to 515 a multicast service infrastructure (see Figure 3 (a) ). To avoid 516 service disruptions on handovers, the uplinks of all proxies SHOULD 517 be adjacent to the same next-hop multicast router. This can either 518 be achieved by arranging proxies within a flat access network, or by 519 upstream tunnels that terminate at a common multicast router. 521 Multicast data submitted by a mobile source will reach the MLD proxy 522 at the MAG that subsequently forwards flows to the upstream, and all 523 downstream interfaces with appropriate subscriptions. Traversing the 524 upstream will lead traffic into the multicast infrastructure (e.g., 525 to a PIM Designated Router) which will route packets to all local 526 MAGs that have joined the group, as well as further upstream 527 according to protocol procedures and forwarding states. 529 On handover, a mobile source will reattach at a new MAG and can 530 continue to send multicast packets as soon as PMIPv6 unicast 531 configurations have completed. Like at the previous MAG, the new MLD 532 proxy will forward data upstream and downstream to subscribers. 533 Listeners local to the previous MAG will continue to receive group 534 traffic via the local multicast distribution infrastructure following 535 aggregated listener reports of the previous proxy. In general, 536 traffic from the mobile source continues to be transmitted via the 537 same next-hop router using the same source address and thus remains 538 unchanged when seen from the wider multicast infrastructure. 540 4.2.1. Considerations for PIM-SM on the Upstream 542 A mobile source that transmits data via an MLD proxy will not be 543 directly connected to a PIM Designated Router as discussed in 544 Section 3.2.3.1. Countermeasures apply correspondingly. 546 A PIM Designated Router that is connected to MLD proxies via 547 individual IP-tunnel interfaces will experience invalid PIM source 548 states on handover. In some implementations of PIM-SM this could 549 lead to interim packet loss (see Section Section 3.2.3.1). This 550 problem can be mitigated by aggregating proxies on a lower layer. 552 4.2.2. SSM Considerations 554 Source-specific subscriptions invalidate with routes, whenever the 555 source moves from or to the MAG/proxy of a subscriber. Multicast 556 forwarding states will rebuild with unicast route changes. However, 557 this may lead to noticeable service disruptions for locally 558 subscribed nodes. 560 4.3. PIM-SM 562 The full-featured multicast routing protocol PIM-SM MAY be deployed 563 in the access network for providing multicast services in parallel to 564 unicast routes. Throughout this section, it is assumed that the 565 PMIPv6 mobility domain is part of a single PIM-SM multicast routing 566 domain with PIM-SM routing functions present at all MAGs and all 567 LMAs. The PIM routing instance at a MAG SHALL then serve as the 568 Designated Router (DR) for all directly attached Mobile Nodes. For 569 expediting handover operations, it is advisable to position PIM 570 Rendezvous Points (RPs) in the core of the PMIPv6 network domain. 571 However, regular IP routing tables need not be present in a PMIPv6 572 deployment, and additional effort is required to establish reverse 573 path forwarding rules as required by PIM-SM. 575 4.3.1. Routing Information Base for PIM-SM 577 In this scenario, PIM-SM will rely on a Multicast Routing Information 578 Base (MRIB) that is generated independently of the policy-based 579 routing rules of PMIPv6. The granularity of mobility-related routing 580 locators required in PIM depends on the complexity (phases) of its 581 deployment. 583 The following information is needed for all phases of PIM. 585 o All routes to networks and nodes (including RPs) that are not 586 mobile members of the PMIPv6 domain MUST be defined consistently 587 among PIM routers and remain uneffected by node mobility. The 588 setup of these general routes is expected to follow the topology 589 of the operator network and is beyond the scope of this document. 591 The following route entries are required at a PIM-operating MAG when 592 phases two or three of PIM, or PIM-SSM are in operation. 594 o All MNs that are directly attached to the MAG generate local 595 routes to their Home Network Prefixes (HNPs) at the corresponding 596 point-to-point attachments that MUST be included into the local 597 MRIB. 599 o All routes to MNs that are attached to distant MAGs of the PMIPv6 600 domain point towards their corresponding LMAs. These routes MUST 601 be made available in the MRIB of all PIM routers (except for the 602 local MAG of attachment), but MAY be eventually expressed by an 603 appropriate default entry. 605 4.3.2. Operations of PIM in Phase One 607 A new mobile source S will transmit multicast data of group G towards 608 its MAG of attachment. Acting as a PIM DR, the access gateway will 609 unicast-encapsulate the multicast packets and forward the data to the 610 Virtual Interface (VI) with encapsulation target RP(G), a process 611 known as PIM source registering. The RP will decapsulate and 612 natively forward the packets down the RP-based distribution tree 613 towards (mobile and stationary) subscribers. 615 On handover, the point-to-point link connecting the mobile source to 616 the old MAG will go down and all (S,*) flows terminate. In response, 617 the previous DR (MAG) deactivates the data encapsulation channels for 618 the transient source (e.g., all DownstreamJPState(S,*,VI) are set to 619 NoInfo state). After reattaching and completing unicast handover 620 negotiations, the mobile source can continue to transmit multicast 621 packets, while being treated as a new source at its new DR (MAG). 622 Source register encapsulation will be immediately initiated, and 623 (S,G) data continue to flow natively down the (*,G) RP-based tree. 625 Source handover management in PIM phase one admits low complexity and 626 remains transparent to receivers. In addition, the source register 627 tunnel management of PIM is a fast protocol operation and little 628 overhead is induced thereof. In a PMIPv6 deployment, PIM RPs MAY be 629 configured to not initiated (S,G) shortest path tress for mobile 630 sources, and thus remain in phase one of the protocol. The price to 631 pay for such simplified deployment lies in possible routing detours 632 by an overall RP-based packet distribution. 634 4.3.3. Operations of PIM in Phase Two 636 After receiving source register packets, a PIM RP eventually will 637 initiated a source-specific Join for creating a shortest path tree to 638 the (mobile) source S, and issue a source register stop at the native 639 arrival of data from S. For initiating an (S,G) tree, the RP, as well 640 as all intermediate routers, require route entries for MN's HNP that 641 - unless the RP coincides with the MAG of S - point towards the 642 corresponding LMA of S. Consequently, the (S,G) tree will proceed 643 from the RP via the (stable) LMA, the LMA-MAG tunnel to the mobile 644 source. This tree can be of lesser routing efficiency than the PIM 645 source register tunnel established in phase one, but provides the 646 advantage of immediate data delivery to receivers that share a MAG 647 with S. 649 On handover, the mobile source reattaches to a new MAG (DR), and 650 PMIPv6 unicast management will transfer the LMA-MAG tunnel to the new 651 point of attachment. However, in the absence of a corresponding 652 multicast forwarding state, the new DR will treat S as a new source 653 and initiate a source registering of PIM phase one with the RP. In 654 response, the PIM RP will recognize the known source at a new 655 (tunnel) interface. A PIM RP implementation compliant with this 656 change can proceed as follows. The RP immediately responds with a 657 register stop, when it receives a register from the new MAG. As the 658 RP had joined the shortest path tree to receive from the source via 659 the LMA, the tree is persistently updated by joins transmitted 660 towards the new MAG on a path via the LMA. In proceeding this way, a 661 quick recovery of PIM transition from phase one to two will be 662 performed per handover. 664 4.3.4. Operations of PIM in Phase Three 666 In response to an exceeded threshold of packet transmission, DRs of 667 receivers eventually will initiated a source-specific Join for 668 creating a shortest path tree to the (mobile) source S, thereby 669 transitioning PIM into the final short-cut phase three. For all 670 receivers not sharing a MAG with S, this (S,G) tree will proceed from 671 the receiving DR via the (stable) LMA, the LMA-MAG tunnel to the 672 mobile source. This tree is of higher routing efficiency than 673 established in the previous phase two, but need not outperform the 674 PIM source register tunnel established in phase one. It provides the 675 advantage of immediate data delivery to receivers that share a MAG 676 with S. 678 On handover, the mobile source reattaches to a new MAG (DR), and 679 PMIPv6 unicast management will transfer the LMA-MAG tunnel to the new 680 point of attachment. However, in the absence of a corresponding 681 multicast forwarding state, the new DR will treat S as a new source 682 and initiate a source registering of PIM phase one. A PIM 683 implementation compliant with this change can recover phase three 684 states in the following way. First, the RP recovers to phase two as 685 described in the previous section, but - being unaware of the LMA in 686 the role of a static mobility anchor - needs to forward data packets 687 that arrived via the source register tunnel down the RP-base tree 688 towards receivers. Such packets will trigger updates of phase three 689 shortest path trees at the DRs of the receivers. Meanwhile packets 690 arriving at the LMA without source register encapsulation are 691 forwarded natively along the shortest path tree towards receivers. 693 In consequence, the PIM transition from phase one to two and three 694 will be quickly recovered per handover, but still leads to an 695 enhanced signaling load and repeated delay variations. 697 4.3.5. PIM-SSM Considerations 699 Source-specific Joins of receivers will guide PIM to operate in SSM 700 mode and lead to an immediate establishment of source-specific 701 shortest path trees. Such (S,G) trees will equal the distribution 702 system of PIM's final phase three (see Section 4.3.4). However, on 703 handover and in the absence of RP-based data distribution, SSM data 704 delivery cannot be resumed via source registering as in PIM phase 705 one. Consequently, data packets transmitted after a handover will be 706 discarded at the MAG until regular tree maintenance has re- 707 established the (S,G) forwarding state at the new MAG. 709 4.3.6. Handover Optimizations for PIM 711 Source-specific shortest path trees are constructed in PIM-SM (phase 712 two and three), and in PIM-SSM that follow LMA-MAG tunnels towards a 713 source. As PIM remains unaware of source mobility management, these 714 trees invalidate under handovers with each tunnel re-establishment at 715 a new MAG. Regular tree maintenance of PIM will recover the states, 716 but remains unsynchronized and too slow to seamlessly preserve PIM 717 data dissemination. 719 A method to quickly recover PIM (S,G) trees under handover SHOULD 720 synchronize multicast state maintenance with unicast handover 721 operations and MAY proceed as follows. On handover, an LMA reads all 722 (S,G) Join states from its corresponding tunnel interface and 723 identifies those source addresses S_i that match moving HNPs. After 724 re-establishing the new tunnel, it SHOULD associate the (S_i,*) Join 725 states with the new tunnel endpoint and immediately trigger a state 726 maintenance (PIM Join) message. In proceeding this way, the source- 727 specific PIM states are transferred to the new tunnel end point and 728 propagated to the new MAG in synchrony with unicast handover 729 procedures. 731 4.4. BIDIR-PIM 733 BIDIR-PIM MAY be deployed in the access network for providing 734 multicast services in parallel to unicast routes. Throughout this 735 section, it is assumed that the PMIPv6 mobility domain is part of a 736 single BIDIR-PIM multicast routing domain with BIDIR-PIM routing 737 functions present at all MAGs and all LMAs. The PIM routing instance 738 at a MAG SHALL then serve as the Designated Forwarder (DF) for all 739 directly attached Mobile Nodes. For expediting handover operations, 740 it is advisable to position BIDIR-PIM Rendezvous Point Addresses 741 (RPAs) in the core of the PMIPv6 network domain. As regular IP 742 routing tables need not be present in a PMIPv6 deployment, reverse 743 path forwarding rules as required by BIDIR-PIM need to be 744 established. 746 4.4.1. Routing Information Base for BIDIR-PIM 748 In this scenario, BIDIR-PIM will rely on a Multicast Routing 749 Information Base (MRIB) that is generated independently of the 750 policy-based routing rules of PMIPv6. The following information is 751 needed. 753 o All routes to networks and nodes (including RPAs) that are not 754 mobile members of the PMIPv6 domain MUST be defined consistently 755 among BIDIR-PIM routers and remain uneffected by node mobility. 756 The setup of these general routes is expected to follow the 757 topology of the operator network and is beyond the scope of this 758 document. 760 4.4.2. Operations of BIDIR-PIM 762 BIDIR-PIM will establish spanning trees across its network domain in 763 conformance to its preconfigured RPAs and the routing information 764 provided. Multicast data transmitted by a mobile source will 765 immediately be forwarded by its DF (MAG) onto the spanning group tree 766 without further protocol operations. 768 On handover, the mobile source re-attaches to a new MAG (DF), which 769 completes unicast network configurations. Thereafter, the source can 770 immediately proceed with multicast packet transmission onto the pre- 771 established distribution tree. BIDIR-PIM does neither require 772 protocol signaling nor additional reconfiguration delays to adapt to 773 source mobility and can be considered the protocol of choice for 774 mobile multicast operations in the access. As multicast streams 775 always flow up to the Rendezvous Point Link, some care should be 776 taken to configure RPAs compliant with network capacities. 778 5. Extended MLD Proxy Function for Optimized Source Mobility in PMIPv6 780 A deployment of MLD Proxies (see [RFC4605]) at MAGs has proven a 781 useful and appropriate approach to multicast in PMIPv6, see 782 [RFC6224], [I-D.ietf-multimob-pmipv6-ropt]. However, deploying 783 unmodified standard proxies can go along with significant performance 784 degradation for mobile senders as discussed along the lines of this 785 document. To overcome these deficits, an optimized approach to 786 multicast source mobility based on extended peering functions among 787 proxies is introduced in this section. Prior to presenting the 788 solution, we will sketch the relevant requirements. 790 Solutions that extend MLD Proxies by additional uplinking functions 791 need to comply to the following requirements. 793 Prevention of Routing Loops In the absence of a full-featured 794 routing logic at an MLD Proxy, simple and locally decidable rules 795 need to prevent source traffic from traversing the network in 796 loops as potentially enabled by multiple uplinks. 798 Unique coverage of receivers Listener functions at Proxies require 799 simple, locally decidable rules to initiate a unique delivery of 800 multicast packets to all receivers. 802 Following different techniques, these requirements are met in the 803 following solutions. 805 5.1. Peering Function for MLD Proxies 807 In this section, we define a peering interface for MLD proxies that 808 allows for a direct data exchange of locally attached multicast 809 sources. Such peering interfaces can be configured - as a direct 810 link or a bidirectional tunnel - between any two proxy instances 811 (locally deployed as in [RFC6224] or remotely) and remain as silent 812 virtual links in regular proxy operations. Data on such link is 813 exchanged only in cases, where one peering proxy directly connects on 814 the downstream to a source of multicast traffic, which the other 815 peering proxy actively subscribes to. Operations are defined for ASM 816 and SSM, but provide superior performance in the presence of source- 817 specific signaling (IGMPv3/MLDv2). 819 5.1.1. Operations at the Multicast Sender 821 An MLD Proxy in the perspective of a sender will see peering 822 interfaces as restricted downstream interfaces. It will install and 823 maintain source filters at its peering links that will restrict data 824 transmission to those packets that originate from a locally attached 825 source at the downstream. In detail, a proxy will extract from its 826 configuration the network prefixes attached to its downstream 827 interfaces and MUST implement a source filter base at its peering 828 interfaces that restricts data transmission to IP source addresses 829 from its local prefixes. This filter base Must be updated, if and 830 only if the downstream configuration changes. In this way, a 831 multihop forwarding on peering links is prevented. Multicast packets 832 that arrive from the upstream interface of the proxy are thus only 833 forwarded to regular downstream interfaces with appropriate 834 subscription states. 836 Multicast traffic arriving from a locally attached source will be 837 forwarded to the regular upstream interface and all downstreams with 838 appropriate subscription states (i.e., regular Proxy operations). In 839 addition, local multicast packets are transferred to those peering 840 interfaces with appropriate subscription states. 842 5.1.2. Operations at the Multicast Listener 844 From the listener side, peering interfaces appear as preferred 845 upstream links. Thus an MLD proxy with peering interconnects will 846 offer several interfaces for pulling remote traffic: the regular 847 upstream and the peerings. Traffic arriving from any of the peering 848 links will be mutually disjoint, but normally also available from the 849 upstream. To prevent duplicate traffic from arriving at the listener 850 side, the proxy 852 o MAY delay aggregated reports to the upstream, and 854 o MUST apply appropriate filters to exclude duplicate streams. 856 In detail, it first issues listener reports (in parallel) to its 857 peering links, which only span one (virtual) hop. Whenever the 858 expected traffic (e.g., SSM channels) does not completely arrive from 859 the peerings after a waiting time (default: 10 ms), additional 860 (complementary, in the case of SSM) reports are sent to the standard 861 upstream interface. 863 After the arrival of traffic from peering links, an MLD proxy MUST 864 install source filters at the upstream in the following way. 866 ASM with IGMPv2/MLDv1 In the presence of Any Source Multicast using 867 IGMPv2/MLDv1, only, the proxy cannot signal source filtering to 868 its upstream. Correspondingly, it applies (S,*) ingress filters 869 at its upstream interface for all sources S seen in traffic of the 870 peering links. It is noteworthy that unwanted traffic is still 871 replicated to the proxy via the access network. 873 ASM with IGMPv3/MLDv2 In the presence of source-specific signaling 874 (IGMPv3/MLDv2), the upstream interface is set to (S,*) exclude 875 mode for all sources S seen in traffic of the peering links. The 876 corresponding source-specific signaling will prevent duplicate 877 traffic forwarding throughout the access network. 879 SSM In the presence of Source Specific Multicast, the proxy will 880 subscribe on its uplink interface to those (S,G) channels, only, 881 that do not arrive via the peering links. 883 In proceeding this way, multicast group data arrive from peering 884 interfaces first, while only peer-wise unavailable traffic is 885 retrieved from the regular upstream interface. 887 6. IANA Considerations 889 TODO. 891 Note to RFC Editor: this section may be removed on publication as an 892 RFC. 894 7. Security Considerations 896 TODO 898 Consequently, no new threats are introduced by this document in 899 addition to those identified as security concerns of [RFC3810], 900 [RFC4605], [RFC5213], and [RFC5844]. 902 However, particular attention should be paid to implications of 903 combining multicast and mobility management at network entities. As 904 this specification allows mobile nodes to initiate the creation of 905 multicast forwarding states at MAGs and LMAs while changing 906 attachments, threats of resource exhaustion at PMIP routers and 907 access networks arrive from rapid state changes, as well as from high 908 volume data streams routed into access networks of limited 909 capacities. In addition to proper authorization checks of MNs, rate 910 controls at replicators MAY be required to protect the agents and the 911 downstream networks. In particular, MLD proxy implementations at 912 MAGs SHOULD carefully procure for automatic multicast state 913 extinction on the departure of MNs, as mobile multicast listeners in 914 the PMIPv6 domain will not actively terminate group membership prior 915 to departure. 917 8. Acknowledgements 919 The authors would like to thank (in alphabetical order) Luis M. 920 Contreras, Muhamma Omer Farooq, Bohao Feng, Dirk von Hugo, Ning Kong, 921 Jouni Korhonen, He-Wu Li, Akbar Rahman, Stig Venaas, Li-Li Wang, Qian 922 Wu, Zhi-Wei Yan for advice, help and reviews of the document. 923 Funding by the German Federal Ministry of Education and Research 924 within the G-LAB Initiative (project HAMcast) is gratefully 925 acknowledged. 927 9. References 929 9.1. Normative References 931 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 932 Requirement Levels", BCP 14, RFC 2119, March 1997. 934 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 935 Listener Discovery (MLD) for IPv6", RFC 2710, 936 October 1999. 938 [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. 939 Thyagarajan, "Internet Group Management Protocol, Version 940 3", RFC 3376, October 2002. 942 [RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery 943 Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. 945 [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, 946 "Protocol Independent Multicast - Sparse Mode (PIM-SM): 947 Protocol Specification (Revised)", RFC 4601, August 2006. 949 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 950 "Internet Group Management Protocol (IGMP) / Multicast 951 Listener Discovery (MLD)-Based Multicast Forwarding 952 ("IGMP/MLD Proxying")", RFC 4605, August 2006. 954 [RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano, 955 "Bidirectional Protocol Independent Multicast (BIDIR- 956 PIM)", RFC 5015, October 2007. 958 [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., 959 and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 961 [RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy 962 Mobile IPv6", RFC 5844, May 2010. 964 [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support 965 in IPv6", RFC 6275, July 2011. 967 9.2. Informative References 969 [I-D.ietf-multimob-pmipv6-ropt] 970 Zuniga, J., Contreras, L., Bernardos, C., Jeon, S., and Y. 971 Kim, "Multicast Mobility Routing Optimizations for Proxy 972 Mobile IPv6", draft-ietf-multimob-pmipv6-ropt-03 (work in 973 progress), February 2013. 975 [RFC2236] Fenner, W., "Internet Group Management Protocol, Version 976 2", RFC 2236, November 1997. 978 [RFC5757] Schmidt, T., Waehlisch, M., and G. Fairhurst, "Multicast 979 Mobility in Mobile IP Version 6 (MIPv6): Problem Statement 980 and Brief Survey", RFC 5757, February 2010. 982 [RFC5845] Muhanna, A., Khalil, M., Gundavelli, S., and K. Leung, 983 "Generic Routing Encapsulation (GRE) Key Option for Proxy 984 Mobile IPv6", RFC 5845, June 2010. 986 [RFC6224] Schmidt, T., Waehlisch, M., and S. Krishnan, "Base 987 Deployment for Multicast Listener Support in Proxy Mobile 988 IPv6 (PMIPv6) Domains", RFC 6224, April 2011. 990 Appendix A. Multiple Upstream Interface Proxy 992 In this section, we document upstream extensions for an MLD proxy 993 that were originally developed during the work on this document. 994 Multiple proxy instances deployed at a single MAG (see Section 3) can 995 be avoided by adding multiple upstream interfaces to a single MLD 996 Proxy. In a typical PMIPv6 deployment, each upstream of a single 997 proxy instance can interconnect to one of the LMAs. With such 998 ambiguous upstream options, appropriate forwarding rules MUST be 999 supplied to 1001 o unambiguously guide traffic forwarding from directly attached 1002 mobile sources, and 1004 o lead listener reports to initiating unique traffic subscriptions. 1006 This can be achieved by a complete set of source- and group-specific 1007 filter rules (e.g., (S,*), (*,G)) installed at proxy interfaces. 1008 These filters MAY be derived in parts from PMIPv6 routing policies, 1009 and can include a default behavior (e.g., (*,*)). 1011 A.1. Operations for Local Multicast Sources 1013 Packets from a locally attached multicast source will be forwarded to 1014 all downstream interfaces with appropriate subscriptions, as well as 1015 up the interface with the matching source-specific filter. 1017 Typically, the upstream interface for a mobile multicast source is 1018 chosen based on the policy routing (e.g., the MAG-LMA tunnel 1019 interface for LMA-based routing or the interface towards the 1020 multicast router for direct routing), but alternate configuriations 1021 MAY be applied. Packets from a locally attached multicast source 1022 will be forwarded to the corresponding upstream interface with the 1023 matching source-specific filter, as well as all the downstream 1024 interfaces with appropriate subscriptions. 1026 A.2. Operations for Local Multicast Subscribers 1028 Multicast listener reports are group-wise aggregated by the MLD 1029 proxy. The aggregated report is issued to the upstream interface 1030 with matching group/channel-specific filter. The choice of the 1031 corresponding upstream interface for aggregated group membership 1032 reports MAY be additionally based on some administrative scoping 1033 rules for scoped multicast group addresses. 1035 In detail, a Multiple Upstream Interface Proxy will provide and 1036 maintain a Multicast Subscription Filter Table that maps source- and 1037 group-specific filters to upstream interfaces. The forwarding 1038 decision for an aggregated MLD listener report is based on the first 1039 matching entry from this table, with the understanding that for 1040 IGMPv3/MLDv2 the MLD Proxy performs a state decomposition , if needed 1041 (i.e., a (*,G) subscription is split into (S,G) and (* \ S,G) in the 1042 presence of (*,G) after (S,G) interface entries), and that 1043 (S,*)-filters are always false in the absence of source-specific 1044 signaling, i.e. in IGMPv2/MLDv1 only domains. 1046 In typical deployment scenarios, specific group services (channels) 1047 could be either associated with selected uplinks to remote LMAs, 1048 while a (*,*) default subscription entry (in the last table line) is 1049 bound to a local routing interface, or selected groups are configured 1050 as local services first, while a (*,*) default entry (in the last 1051 table line) points to a remote uplink that provides the general 1052 multicast support. 1054 Appendix B. Evaluation of Traffic Flows 1056 TODO 1058 Appendix C. Change Log 1060 The following changes have been made from version 1061 draft-ietf-multimob-pmipv6-source-02: 1063 1. Added clarifications and details as requested by the working 1064 group, resolved nits. 1066 2. Moved Multiple Upstream MLD Proxy to Appendix in response to WG 1067 desire. 1069 3. Updated references. 1071 The following changes have been made from version 1072 draft-ietf-multimob-pmipv6-source-01: 1074 1. Added clarifications and details as requested by the working 1075 group, resolved nits. 1077 2. Detailed out operations of Multiple Upstream MLD Proxies. 1079 3. Clarified operations of MLD proxies with peering links. 1081 4. Many editorial improvements. 1083 5. Updated references. 1085 The following changes have been made from version 1086 draft-ietf-multimob-pmipv6-source-00: 1088 1. Direct routing with PIM-SM and PIM-SSM has been added. 1090 2. PMIP synchronization with PIM added for improved handover. 1092 3. Direct routing with BIDIR-PIM has been added. 1094 4. MLD Proxy extensions requirements added. 1096 5. Peering of MLD Proxies added. 1098 6. First sketch of multiple upstream proxy added. 1100 7. Editorial improvements. 1102 8. Updated references. 1104 Authors' Addresses 1106 Thomas C. Schmidt (editor) 1107 HAW Hamburg 1108 Berliner Tor 7 1109 Hamburg 20099 1110 Germany 1112 Email: schmidt@informatik.haw-hamburg.de 1113 URI: http://inet.cpt.haw-hamburg.de/members/schmidt 1115 Shuai Gao 1116 Beijing Jiaotong University 1117 Beijing, 1118 China 1120 Phone: 1121 Fax: 1122 Email: shgao@bjtu.edu.cn 1123 URI: 1125 Hong-Ke Zhang 1126 Beijing Jiaotong University 1127 Beijing, 1128 China 1130 Phone: 1131 Fax: 1132 Email: hkzhang@bjtu.edu.cn 1133 URI: 1135 Matthias Waehlisch 1136 link-lab & FU Berlin 1137 Hoenower Str. 35 1138 Berlin 10318 1139 Germany 1141 Email: mw@link-lab.net