idnits 2.17.1 draft-ietf-multimob-pmipv6-source-08.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (March 3, 2014) is 3706 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Experimental ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 4601 (Obsoleted by RFC 7761) == Outdated reference: A later version (-10) exists of draft-ietf-multimob-fmipv6-pfmipv6-multicast-03 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MULTIMOB Group T. Schmidt, Ed. 3 Internet-Draft HAW Hamburg 4 Intended status: Experimental S. Gao 5 Expires: September 4, 2014 H. Zhang 6 Beijing Jiaotong University 7 M. Waehlisch 8 link-lab & FU Berlin 9 March 3, 2014 11 Mobile Multicast Sender Support in Proxy Mobile IPv6 (PMIPv6) Domains 12 draft-ietf-multimob-pmipv6-source-08 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 a base solution and an experimental protocol 21 to support mobile multicast senders in Proxy Mobile IPv6 domains for 22 all three scenarios. Protocol optimizations for synchronizing PMIPv6 23 with PIM, as well as a peering function for MLD Proxies are defined. 24 Mobile sources always remain agnostic of multicast mobility 25 operations. 27 Requirements Language 29 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 30 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 31 document are to be interpreted as described in RFC 2119 [RFC2119]. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at http://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on September 4, 2014. 50 Copyright Notice 52 Copyright (c) 2014 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 68 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 3. Base Solution for Source Mobility and PMIPv6 Routing . . . . 4 70 3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4 71 3.2. Base Solution for Source Mobility: Details . . . . . . . 8 72 3.2.1. Operations of the Mobile Node . . . . . . . . . . . . 8 73 3.2.2. Operations of the Mobile Access Gateway . . . . . . . 8 74 3.2.3. Operations of the Local Mobility Anchor . . . . . . . 8 75 3.2.4. IPv4 Support . . . . . . . . . . . . . . . . . . . . 9 76 3.2.5. Efficiency of the Distribution System . . . . . . . . 10 77 4. Direct Multicast Routing . . . . . . . . . . . . . . . . . . 11 78 4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 11 79 4.2. MLD Proxies at MAGs . . . . . . . . . . . . . . . . . . . 12 80 4.2.1. Considerations for PIM-SM on the Upstream . . . . . . 13 81 4.2.2. SSM Considerations . . . . . . . . . . . . . . . . . 13 82 4.3. PIM-SM at MAGs . . . . . . . . . . . . . . . . . . . . . 13 83 4.3.1. Routing Information Base for PIM-SM . . . . . . . . . 13 84 4.3.2. Operations of PIM in Phase One (RP Tree) . . . . . . 14 85 4.3.3. Operations of PIM in Phase Two (Register-Stop) . . . 15 86 4.3.4. Operations of PIM in Phase Three (Shortest-Path Tree) 15 87 4.3.5. PIM-SSM Considerations . . . . . . . . . . . . . . . 16 88 4.3.6. Handover Optimizations for PIM . . . . . . . . . . . 16 89 4.4. BIDIR-PIM . . . . . . . . . . . . . . . . . . . . . . . . 17 90 4.4.1. Routing Information Base for BIDIR-PIM . . . . . . . 17 91 4.4.2. Operations of BIDIR-PIM . . . . . . . . . . . . . . . 17 92 5. MLD Proxy Peering Function for Optimized Source Mobility in 93 PMIPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 94 5.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 18 95 5.2. Overview . . . . . . . . . . . . . . . . . . . . . . . . 18 96 5.3. Operations in Support of Multicast Senders . . . . . . . 19 97 5.4. Operations in Support of Multicast Listeners . . . . . . 19 99 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 100 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21 101 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22 102 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 103 9.1. Normative References . . . . . . . . . . . . . . . . . . 22 104 9.2. Informative References . . . . . . . . . . . . . . . . . 23 105 Appendix A. Multiple Upstream Interface Proxy . . . . . . . . . 23 106 A.1. Operations for Local Multicast Sources . . . . . . . . . 24 107 A.2. Operations for Local Multicast Subscribers . . . . . . . 24 108 Appendix B. Implementation . . . . . . . . . . . . . . . . . . . 25 109 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 25 110 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 112 1. Introduction 114 Proxy Mobile IPv6 (PMIPv6) [RFC5213] extends Mobile IPv6 (MIPv6) 115 [RFC6275] by network-based management functions that enable IP 116 mobility for a host without requiring its participation in any 117 mobility-related signaling. Additional network entities called the 118 Local Mobility Anchor (LMA), and Mobile Access Gateways (MAGs), are 119 responsible for managing IP mobility on behalf of the mobile node 120 (MN). An MN connected to a PMIPv6 domain, which only operates 121 according to the base specifications of [RFC5213], cannot participate 122 in multicast communication, as MAGs will discard group packets. 124 Multicast support for mobile listeners can be enabled within a PMIPv6 125 domain by deploying MLD proxy functions at Mobile Access Gateways, 126 and multicast routing functions at Local Mobility Anchors [RFC6224]. 127 This base deployment option is the simplest way to PMIPv6 multicast 128 extensions in the sense that it follows the common PMIPv6 traffic 129 model and neither requires new protocol operations nor additional 130 infrastructure entities. Standard software functions need to be 131 activated on PMIPv6 entities, only, at the price of possibly non- 132 optimal multicast routing. 134 Alternate solutions leverage performance optimization by providing 135 multicast routing at the access gateways directly 136 [I-D.ietf-multimob-fmipv6-pfmipv6-multicast], or by selective route 137 optimization schemes [RFC7028]. Such approaches (partially) follow 138 the model of providing multicast data services in parallel to PMIPv6 139 unicast routing [I-D.ietf-multimob-handover-optimization]. 141 Multicast listener support satisfies the needs of receptive use cases 142 such as IPTV or server-centric gaming on mobiles. However, current 143 trends in the Internet develop towards user-centric, highly 144 interactive group applications like user generated streaming, 145 conferencing, collective mobile sensing, etc. Many of these popular 146 applications create group content at end systems and can largely 147 profit from a direct data transmission to a multicast-enabled 148 network. 150 This document describes the support of mobile multicast senders in 151 Proxy Mobile IPv6 domains subsequently for the base deployment 152 scenario [RFC6224], for direct traffic distribution within an ISP's 153 access network, as well as for selective route optimization schemes. 154 The contribution of this work reflects the source mobility problem as 155 discussed in [RFC5757]. Mobile Nodes in this setting remain agnostic 156 of multicast mobility operations. 158 2. Terminology 160 This document uses the terminology as defined for the mobility 161 protocols [RFC6275], [RFC5213] and [RFC5844], as well as the 162 multicast routing [RFC4601] and edge related protocols [RFC3376], 163 [RFC3810] and [RFC4605]. 165 3. Base Solution for Source Mobility and PMIPv6 Routing 167 3.1. Overview 169 The reference scenario for multicast deployment in Proxy Mobile IPv6 170 domains is illustrated in Figure 1. It displays the general setting 171 for source mobility - Mobile Nodes (MNs) with Home Network Prefixes 172 (HNPs) that receive services via tunnels, which are spanned between a 173 Local Mobility Anchor Address (LMAA) and a Proxy Care-of-Address 174 (Proxy-CoA) at a Mobility Access Gateway (MAG). MAGs play the role 175 of first-hop access routers that serve multiple MNs on the downstream 176 while running an MLD/IGMP proxy instance for every LMA upstream 177 tunnel. 179 +-------------+ 180 | Multicast | 181 | Listeners | 182 +-------------+ 183 | 184 *** *** *** *** 185 * ** ** ** * 186 * * 187 * Fixed Internet * 188 * * 189 * ** ** ** * 190 *** *** *** *** 191 / \ 192 +----+ +----+ 193 |LMA1| |LMA2| Multicast Anchor 194 +----+ +----+ 195 LMAA1 | | LMAA2 196 | | 197 \\ //\\ 198 \\ // \\ 199 \\ // \\ Unicast Tunnel 200 \\ // \\ 201 \\ // \\ 202 \\ // \\ 203 Proxy-CoA1 || || Proxy-CoA2 204 +----+ +----+ 205 |MAG1| |MAG2| MLD Proxy 206 +----+ +----+ 207 | | | 208 MN-HNP1 | | MN-HNP2 | MN-HNP3 209 | | | 210 MN1 MN2 MN3 212 Multicast Sender + Listener(s) 214 Figure 1: Reference Network for Multicast Deployment in PMIPv6 216 An MN in a PMIPv6 domain will decide on multicast data transmission 217 completely independent of its current mobility conditions. It will 218 send packets as initiated by applications, using its source address 219 with Home Network Prefix (HNP) and a multicast destination address 220 chosen by application needs. Multicast packets will arrive at the 221 currently active MAG via one of its downstream local (wireless) 222 links. A multicast unaware MAG would simply discard these packets in 223 the absence of instructions for packet processing, i.e., a multicast 224 routing information base (MRIB). 226 An MN can successfully distribute multicast data in PMIPv6, if MLD 227 proxy functions are deployed at the MAG as described in [RFC6224]. 228 In this set-up, the MLD proxy instance serving a mobile multicast 229 source has configured its upstream interface at the tunnel towards 230 MN's corresponding LMA. For each LMA, there will be a separate 231 instance of an MLD proxy. 233 According to the specifications given in [RFC4605], multicast data 234 arriving from a downstream interface of an MLD proxy will be 235 forwarded to the upstream interface and to all but the incoming 236 downstream interfaces that have appropriate forwarding states for 237 this group. Thus multicast streams originating from an MN will 238 arrive at the corresponding LMA and directly at all mobile receivers 239 co-located at the same MAG and MLD proxy instance. Serving as the 240 designated multicast router or an additional MLD proxy, the LMA 241 forwards data to the fixed Internet, whenever forwarding states are 242 maintained by multicast routing. If the LMA is acting as another MLD 243 proxy, it will forward the multicast data to its upstream interface, 244 and to downstream interfaces with matching subscriptions, 245 accordingly. 247 In case of a handover, the MN (being unaware of IP mobility) can 248 continue to send multicast packets as soon as network connectivity is 249 re-established. At this time, the MAG has determined the 250 corresponding LMA, and IPv6 unicast address configuration (including 251 PMIPv6 bindings) has been completed. Still multicast packets 252 arriving at the MAG are discarded (if not buffered) until the MAG has 253 completed the following steps. 255 1. The MAG has determined that the MN is admissible to multicast 256 services. 258 2. The MAG has added the new downstream link to the MLD proxy 259 instance with up-link to the corresponding LMA. 261 As soon as the MN's uplink is associated with the corresponding MLD 262 proxy instance, multicast packets are forwarded again to the LMA and 263 eventually to receivers within the PMIP domain (see the call flow in 264 Figure 2). In this way, multicast source mobility is transparently 265 enabled in PMIPv6 domains that deploy the base scenario for 266 multicast. 268 MN1 MAG1 MN2 MAG2 LMA 269 | | | | | 270 | | Mcast Data | | | 271 | |<---------------+ | | 272 | | Mcast Data | | | 273 | Join(G) +================================================>| 274 +--------------> | | | | 275 | Mcast Data | | | | 276 |<---------------+ | | | 277 | | | | | 278 | < Movement of MN 2 to MAG2 & PMIP Binding Update > | 279 | | | | | 280 | | |--- Rtr Sol -->| | 281 | | |<-- Rtr Adv ---| | 282 | | | | | 283 | | | < MLD Proxy Configuration > | 284 | | | | | 285 | | | (MLD Query) | | 286 | | |<--------------+ | 287 | | | Mcast Data | | 288 | | +-------------->| | 289 | | | | Mcast Data | 290 | | | +===============>| 291 | | | | | 292 | | Mcast Data | | | 293 | |<================================================+ 294 | Mcast Data | | | | 295 |<---------------+ | | | 296 | | | | | 298 Figure 2: Call Flow for Group Communication in Multicast-enabled PMIP 300 These multicast deployment considerations likewise apply for mobile 301 nodes that operate with their IPv4 stack enabled in a PMIPv6 domain. 302 PMIPv6 can provide IPv4 home address mobility support [RFC5844]. 303 IPv4 multicast is handled by an IGMP proxy function at the MAG in an 304 analogous way. 306 Following these deployment steps, multicast traffic distribution 307 transparently inter-operates with PMIPv6. It is worth noting that an 308 MN - while being attached to the same MAG as the mobile source, but 309 associated with a different LMA - cannot receive multicast traffic on 310 a shortest path. Instead, multicast streams flow up to the LMA of 311 the mobile source, are transferred to the LMA of the mobile listener 312 and tunneled downwards to the MAG again (see Section 5 for further 313 optimizations). 315 3.2. Base Solution for Source Mobility: Details 317 A support of multicast source mobility in PMIPv6 requires to deploy 318 general multicast functions at PMIPv6 routers and to define their 319 interaction with the PMIPv6 protocol in the following way. 321 3.2.1. Operations of the Mobile Node 323 A Mobile Node willing to send multicast data will proceed as if 324 attached to the fixed Internet. No specific mobility or other 325 multicast related functionalities are required at the MN. 327 3.2.2. Operations of the Mobile Access Gateway 329 A Mobile Access Gateway is required to have MLD proxy instances 330 deployed, one for each tunnel to an LMA, which serves as its unique 331 upstream link (cf., [RFC6224]). On the arrival of an MN, the MAG 332 decides on the mapping of downstream links to a proxy instance and 333 the upstream link to the LMA based on the regular Binding Update List 334 as maintained by PMIPv6 standard operations. When multicast data is 335 received from the MN, the MAG MUST identify the corresponding proxy 336 instance from the incoming interface and forwards multicast data 337 upstream according to [RFC4605]. 339 The MAG MAY apply special admission control to enable multicast data 340 transmission from an MN. It is advisable to take special care that 341 MLD proxy implementations do not redistribute multicast data to 342 downstream interfaces without appropriate subscriptions in place. 344 3.2.3. Operations of the Local Mobility Anchor 346 For any MN, the Local Mobility Anchor acts as the persistent Home 347 Agent and at the same time as the default multicast upstream for the 348 corresponding MAG. It will manage and maintain a multicast 349 forwarding information base for all group traffic arriving from its 350 mobile sources. It SHOULD participate in multicast routing functions 351 that enable traffic redistribution to all adjacent LMAs within the 352 PMIPv6 domain and thereby ensure a continuous receptivity while the 353 source is in motion. 355 3.2.3.1. Local Mobility Anchors Operating PIM 357 Local Mobility Anchors that operate the PIM-SM routing protocol 358 [RFC4601] will require sources to be directly connected for sending 359 PIM registers to the RP. This does not hold in a PMIPv6 domain, as 360 MAGs are routers intermediate to MN and the LMA. In this sense, MNs 361 are multicast sources external to the PIM-SM domain. 363 To mitigate this incompatibility common to all subsidiary MLD proxy 364 domains, the LMA MUST act as a PIM Border Router and activate the 365 Border-bit. In this case, the DirectlyConnected(S) is treated as 366 being TRUE for mobile sources and the PIM-SM forwarding rule "iif == 367 RPF_interface(S)" is relaxed to be TRUE, as the incoming tunnel 368 interface from MAG to LMA is considered as not part of the PIM-SM 369 component of the LMA (see A.1 of [RFC4601] ). 371 In addition, an LMA serving as PIM Designated Router (DR) is 372 connected to MLD proxies via individual IP-tunnel interfaces and will 373 experience changing PIM source states on handover. As the incoming 374 interface connects to a point-to-point link, PIM Assert contention is 375 not active, and incoming interface validation is only performed by 376 Reverse Path Forwarding (RPF) checks. Consequently, a PIM DR SHOULD 377 update incoming source states, as soon as RPF inspection succeeds, 378 i.e., after PMIPv6 forwarding state update. Consequently, PIM 379 routers SHOULD be able to manage these state changes, but some 380 implementations are expected to incorrectly refuse packets until the 381 previous state has timed out. 383 Notably, running BIDIR-PIM [RFC5015] on LMAs remains robust with 384 respect to source location and does not require special 385 configurations or state management for sources. 387 3.2.4. IPv4 Support 389 An MN in a PMIPv6 domain may use an IPv4 address transparently for 390 communication as specified in [RFC5844]. For this purpose, an LMA 391 can register an IPv4-Proxy-CoA in its Binding Cache and the MAG can 392 provide IPv4 support in its access network. Correspondingly, 393 multicast membership management will be performed by the MN using 394 IGMP. For multicast support on the network side, an IGMP proxy 395 function needs to be deployed at MAGs in exactly the same way as for 396 IPv6. [RFC4605] defines IGMP proxy behaviour in full agreement with 397 IPv6/MLD. Thus IPv4 support can be transparently provided following 398 the obvious deployment analogy. 400 For a dual-stack IPv4/IPv6 access network, the MAG proxy instances 401 SHOULD choose multicast signaling according to address configurations 402 on the link, but MAY submit IGMP and MLD queries in parallel, if 403 needed. It should further be noted that the infrastructure cannot 404 identify two data streams as identical when distributed via an IPv4 405 and IPv6 multicast group. Thus duplicate data may be forwarded on a 406 heterogeneous network layer. 408 A particular note is worth giving the scenario of [RFC5845] in which 409 overlapping private address spaces of different operators can be 410 hosted in a PMIP domain by using GRE encapsulation with key 411 identification. This scenario implies that unicast communication in 412 the MAG-LMA tunnel can be individually identified per MN by the GRE 413 keys. This scenario still does not impose any special treatment of 414 multicast communication for the following reasons. 416 Multicast streams from and to MNs arrive at a MAG on point-to-point 417 links (identical to unicast). Multicast data transmission from the 418 MAG to the corresponding LMA is link-local between the routers and 419 routing/forwarding remains independent of any individual MN. So the 420 MAG-proxy and the LMA SHOULD NOT use GRE key identifiers, but plain 421 GRE encapsulation in multicast communication (including MLD queries 422 and reports). Multicast traffic is transmitted as router-to-router 423 forwarding via the MAG-to-LMA tunnels and according to the multicast 424 routing information base (MRIB) of the MAG or the LMA. It remains 425 independent of MN's unicast addresses, while the MAG proxy instance 426 redistributes multicast data down the point-to-point links 427 (interfaces) according to its local subscription states, independent 428 of IP addresses of the MN. 430 3.2.5. Efficiency of the Distribution System 432 The distribution system of the base solution directly follows PMIPv6 433 routing rules, and organizes multicast domains with respect to LMAs. 434 Thus, no coordination between address spaces or services is required 435 between the different instances, provided their associated LMAs 436 belong to disjoint multicast domains. Routing is optimal for 437 communication between MNs of the same domain, or stationary 438 subscribers. 440 In the following, efficiency-related issues remain. 442 Multicast reception at LMA In the current deployment scenario, the 443 LMA will receive all multicast traffic originating from its 444 associated MNs. There is no mechanism to suppress upstream 445 forwarding in the absence of receivers. 447 MNs on the same MAG using different LMAs For a mobile receiver and a 448 source that use different LMAs, the traffic has to go up to one 449 LMA, cross over to the other LMA, and then be tunneled back to the 450 same MAG, causing redundant flows in the access network and at the 451 MAG. 453 These remaining deficits in routing efficiency can be resolved by 454 adding peering functions to MLD proxies as described in Section 5. 456 4. Direct Multicast Routing 458 There are deployment scenarios, where multicast services are 459 available throughout the access network independent of the PMIPv6 460 routing system [RFC7028]. In these cases, the visited networks grant 461 a local content distribution service (in contrast to LMA-based home 462 subscription) with locally optimized traffic flows. It is also 463 possible to deploy a mixed service model of local and LMA-based 464 subscriptions, provided a unique way of service selection is 465 implemented. For example, access routers (MAGs) could decide on 466 service access based on the multicast address G or the SSM channel 467 (S,G) under request (see Appendix A for further discussions). 469 4.1. Overview 471 Direct multicast access can be supported by 473 o native multicast routing provided by one multicast router that is 474 neighboring MLD proxies deployed at MAGs within a flat access 475 network, or via tunnel uplinks, 477 o a multicast routing protocol such as PIM-SM [RFC4601] or BIDIR-PIM 478 [RFC5015] deployed at the MAGs. 480 *** *** *** *** 481 * ** ** ** * 482 * * 483 * Multicast * 484 +----+ * Infrastructure * +----+ 485 |LMA | * ** ** ** * |LMA | 486 +----+ *** *** *** *** +----+ 487 | // \\ | 488 \\ // \\ PMIP (unicast) | 489 PMIP \\ // \\ // \\ ** *** *** ** // 490 (unicast) \\ // \\ // \\ * ** ** ** // 491 \\ // \\ // \\* Multicast *// 492 || || || || * || Routing || * 493 +----+ +----+ * +----+ +----+ * 494 MLD Proxy |MAG1| |MAG2| * |MAG1| |MAG2| * 495 +----+ +----+ *+----+ ** ** +----+* 496 | | | | |*** *** ***| 497 | | | | | | 498 MN1 MN2 MN3 MN1 MN2 MN3 500 (a) Multicast Access at Proxy Uplink (b) Multicast Routing at MAG 502 Figure 3: Reference Networks for (a) Proxy-assisted Direct Multicast 503 Access and (b) Dynamic Multicast Routing at MAGs 505 Figure 3 displays the corresponding deployment scenarios, which 506 separate multicast from PMIPv6 unicast routing. It is assumed 507 throughout these scenarios that all MAGs (MLD proxies) are linked to 508 a single multicast routing domain. Notably, this scenario requires 509 coordination of multicast address utilization and service bindings. 511 Multicast traffic distribution can be simplified in these scenarios. 512 A single proxy instance at MAGs with up-link into the multicast 513 domain will serve as a first hop multicast gateway and avoid traffic 514 duplication or detour routing. Multicast routing functions at MAGs 515 will seamlessly embed access gateways within a multicast cloud. 516 However, mobility of the multicast source in this scenario will 517 require some multicast routing protocols to rebuild distribution 518 trees. This can cause significant service disruptions or delays (see 519 [RFC5757] for further aspects). Deployment details are specific to 520 the multicast routing protocol in use, in the following described for 521 common protocols. 523 4.2. MLD Proxies at MAGs 525 In a PMIPv6 domain, single MLD proxy instances can be deployed at 526 each MAG that enable multicast service at the access via an uplink to 527 a multicast service infrastructure (see Figure 3 (a) ). To avoid 528 service disruptions on handovers, the uplinks of all proxies SHOULD 529 be adjacent to the same next-hop multicast router. This can either 530 be achieved by arranging proxies within a flat access network, or by 531 upstream tunnels that terminate at a common multicast router. 533 Multicast data submitted by a mobile source will reach the MLD proxy 534 at the MAG that subsequently forwards flows to the upstream, and all 535 downstream interfaces with appropriate subscriptions. Traversing the 536 upstream will transfer traffic into the multicast infrastructure 537 (e.g., to a PIM Designated Router) which will route packets to all 538 local MAGs that have joined the group, as well as further upstream 539 according to protocol procedures and forwarding states. 541 On handover, a mobile source will reattach to a new MAG and can 542 continue to send multicast packets as soon as PMIPv6 unicast 543 configurations have been completed. Like at the previous MAG, the 544 new MLD proxy will forward data upstream and downstream to 545 subscribers. Listeners local to the previous MAG will continue to 546 receive group traffic via the local multicast distribution 547 infrastructure following aggregated listener reports of the previous 548 proxy. In general, traffic from the mobile source continues to be 549 transmitted via the same next-hop multicast router using the same 550 source address and thus remains unchanged when seen from the wider 551 multicast infrastructure. 553 4.2.1. Considerations for PIM-SM on the Upstream 555 A mobile source that transmits data via an MLD proxy will not be 556 directly connected to a PIM Designated Router as discussed in 557 Section 3.2.3.1. Countermeasures apply correspondingly. 559 A PIM Designated Router that is connected to MLD proxies via 560 individual IP-tunnel interfaces will experience invalid PIM source 561 states on handover. In some implementations of PIM-SM this could 562 lead to an interim packet loss (see Section 3.2.3.1). This problem 563 can be mitigated by aggregating proxies on a lower layer. 565 4.2.2. SSM Considerations 567 Source-specific subscriptions invalidate with routes, whenever the 568 source moves from or to the MAG/proxy of a subscriber. Multicast 569 forwarding states will rebuild with unicast route changes. However, 570 this may lead to noticeable service disruptions for locally 571 subscribed nodes. 573 4.3. PIM-SM at MAGs 575 The full-featured multicast routing protocol PIM-SM MAY be deployed 576 in the access network for providing multicast services in parallel to 577 unicast routes (see Figure 3 b). Throughout this section, it is 578 assumed that the PMIPv6 mobility domain is part of a single PIM-SM 579 multicast routing domain with PIM-SM routing functions present at all 580 MAGs and all LMAs. The PIM routing instance at a MAG SHALL then 581 serve as the Designated Router (DR) for all directly attached Mobile 582 Nodes. For expediting handover operations, it is advisable to 583 position PIM Rendezvous Points (RPs) in the core of the PMIPv6 584 network domain. However, regular IP routing tables need not be 585 present in a PMIPv6 deployment, and additional effort is required to 586 establish reverse path forwarding rules as required by PIM-SM. 588 4.3.1. Routing Information Base for PIM-SM 590 In this scenario, PIM-SM will rely on a Multicast Routing Information 591 Base (MRIB) that is generated independently of the policy-based 592 routing rules of PMIPv6. The granularity of mobility-related routing 593 locators required in PIM depends on the complexity (specific phase) 594 of its deployment. 596 For all three phases in the operation of PIM (see [RFC4601]), the 597 following information is needed. 599 o All routes to networks and nodes (including RPs) that are not 600 mobile members of the PMIPv6 domain MUST be defined consistently 601 among PIM routers and MUST remain unaffected by node mobility. 602 The setup of these general routes is expected to follow the 603 topology of the operator network and is beyond the scope of this 604 document. 606 The following route entries are required at a PIM-operating MAG when 607 phases two or three of PIM, or PIM-SSM are in operation. 609 o Local routes to the Home Network Prefixes (HNPs) of all MNs 610 associated with their corresponding point-to-point attachments 611 that MUST be included in the local MRIB. 613 o All routes to MNs that are attached to distant MAGs of the PMIPv6 614 domain point towards their corresponding LMAs. These routes MUST 615 be made available in the MRIB of all PIM routers (except for the 616 local MAG of attachment), but MAY be eventually expressed by an 617 appropriate default entry. 619 4.3.2. Operations of PIM in Phase One (RP Tree) 621 A new mobile source S will transmit multicast data of group G towards 622 its MAG of attachment. Acting as a PIM DR, the access gateway will 623 unicast-encapsulate the multicast packets and forward the data to the 624 Virtual Interface (VI) with encapsulation target RP(G), a process 625 known as PIM source registering. The RP will decapsulate and 626 natively forward the packets down the RP-based distribution tree 627 towards (mobile and stationary) subscribers. 629 On handover, the point-to-point link connecting the mobile source to 630 the old MAG will go down and all (S,*) flows terminate. In response, 631 the previous DR (MAG) deactivates the data encapsulation channels for 632 the transient source (i.e., all DownstreamJPState(S,*,VI) are set to 633 NoInfo state). After reattaching and completing unicast handover 634 negotiations, the mobile source can continue to transmit multicast 635 packets, while being treated as a new source at its new DR (MAG). 636 Source register encapsulation will be immediately initiated, and 637 (S,G) data continue to flow natively down the (*,G) RP-based tree. 639 Source handover management in PIM phase one admits low complexity and 640 remains transparent to receivers. In addition, the source register 641 tunnel management of PIM is a fast protocol operation and little 642 overhead is induced thereof. In a PMIPv6 deployment, PIM RPs MAY be 643 configured to not initiated (S,G) shortest path trees for mobile 644 sources, and thus remain in phase one of the protocol. The price to 645 pay for such simplified deployment lies in possible routing detours 646 by an overall RP-based packet distribution. 648 4.3.3. Operations of PIM in Phase Two (Register-Stop) 650 After receiving source register packets, a PIM RP eventually will 651 initiate a source-specific Join for creating a shortest path tree to 652 the (mobile) source S, and issue a source register stop at the native 653 arrival of data from S. For initiating an (S,G) tree, the RP, as well 654 as all intermediate routers, require route entries for the HNP of the 655 MN that - unless the RP coincides with the MAG of S - point towards 656 the corresponding LMA of S. Consequently, the (S,G) tree will proceed 657 from the RP via the (stable) LMA, down the LMA-MAG tunnel to the 658 mobile source. This tree can be of lower routing efficiency than the 659 PIM source register tunnel established in phase one. 661 On handover, the mobile source reattaches to a new MAG (DR), and 662 PMIPv6 unicast management will transfer the LMA-MAG tunnel to the new 663 point of attachment. However, in the absence of a corresponding 664 multicast forwarding state, the new DR will treat S as a new source 665 and initiate a source registering of PIM phase one with the RP. In 666 response, the PIM RP will recognize the known source at a new 667 (tunnel) interface and immediately responds with a register stop. As 668 the RP had previously joined the shortest path tree towards the 669 source via the LMA, it will see an RPF change when data arrives at a 670 new interface. Implementation-dependent, this can trigger an update 671 of the PIM MRIB and trigger a new PIM Join message that will install 672 the multicast forwarding state missing at the new MAG. Otherwise, 673 the tree is periodically updated by Joins transmitted towards the new 674 MAG on a path via the LMA. In proceeding this way, a quick recovery 675 of PIM transition from phase one to two will be performed per 676 handover. 678 4.3.4. Operations of PIM in Phase Three (Shortest-Path Tree) 680 In response to an exceeded threshold of packet transmission, DRs of 681 receivers eventually will initiate a source-specific Join for 682 creating a shortest path tree to the (mobile) source S, thereby 683 transitioning PIM into the final short-cut phase three. For all 684 receivers not sharing a MAG with S, this (S,G) tree will range from 685 the receiving DR via the (stable) LMA, the LMA-MAG tunnel, and the 686 serving MAG to the mobile source. This tree is of higher routing 687 efficiency than that established in the previous phase two, but need 688 not outperform the PIM source register tunnel established in phase 689 one. It provides the advantage of immediate data delivery to 690 receivers that share a MAG with S. 692 On handover, the mobile source reattaches to a new MAG (DR), and 693 PMIPv6 unicast management will transfer the LMA-MAG tunnel to the new 694 point of attachment. However, in the absence of a corresponding 695 multicast forwarding state, the new DR will treat S as a new source 696 and initiate a source registering of PIM phase one. A PIM 697 implementation compliant with this change can recover phase three 698 states in the following way. First, the RP recovers to phase two as 699 described in the previous section, and will not forward data arriving 700 via the source register tunnel. Tree maintenance eventually 701 triggered by the RPF change (see Section 4.3.3) will generate proper 702 states for a native forwarding from the new MAG via the LMA. 703 Thereafter, packets arriving at the LMA without source register 704 encapsulation are forwarded natively along the shortest path tree 705 towards receivers. 707 In consequence, the PIM transitions from phase one to two and to 708 three will be quickly recovered per handover, but still lead to an 709 enhanced signaling load and intermediate packet loss. 711 4.3.5. PIM-SSM Considerations 713 Source-specific Joins of receivers will guide PIM to operate in SSM 714 mode and lead to an immediate establishment of source-specific 715 shortest path trees. Such (S,G) trees will equal the distribution 716 system of PIM's final phase three (see Section 4.3.4). However, on 717 handover and in the absence of RP-based data distribution, SSM data 718 delivery cannot be resumed via source registering as in PIM phase 719 one. Consequently, data packets transmitted after a handover will be 720 discarded at the MAG until regular tree maintenance has reestablished 721 the (S,G) forwarding state at the new MAG. 723 4.3.6. Handover Optimizations for PIM 725 Source-specific shortest path trees are constructed in PIM-SM (phase 726 two and three), and in PIM-SSM that follow LMA-MAG tunnels towards a 727 source. As PIM remains unaware of source mobility management, these 728 trees invalidate under handovers with each tunnel re-establishment at 729 a new MAG. Regular tree maintenance of PIM will recover the states, 730 but remains unsynchronized and too slow to seamlessly preserve PIM 731 data distribution services. 733 A method to quickly recover PIM (S,G) trees under handover SHOULD 734 synchronize multicast state maintenance with unicast handover 735 operations and can proceed as follows. On handover, an LMA reads all 736 (S,G) Join states from its corresponding tunnel interface and 737 identifies those source addresses S_i that match moving HNPs. After 738 re-establishing the new tunnel, it SHOULD associate the (S_i,*) Join 739 states with the new tunnel endpoint and immediately trigger a state 740 maintenance (PIM Join) message. In proceeding this way, the source- 741 specific PIM states are transferred to the new tunnel end point and 742 propagated to the new MAG in synchrony with unicast handover 743 procedures. 745 4.4. BIDIR-PIM 747 BIDIR-PIM MAY be deployed in the access network for providing 748 multicast services in parallel to unicast routes. Throughout this 749 section, it is assumed that the PMIPv6 mobility domain is part of a 750 single BIDIR-PIM multicast routing domain with BIDIR-PIM routing 751 functions present at all MAGs and all LMAs. The PIM routing instance 752 at a MAG SHALL then serve as the Designated Forwarder (DF) for all 753 directly attached Mobile Nodes. For expediting handover operations, 754 it is advisable to position BIDIR-PIM Rendezvous Point Addresses 755 (RPAs) in the core of the PMIPv6 network domain. As regular IP 756 routing tables need not be present in a PMIPv6 deployment, reverse 757 path forwarding rules as required by BIDIR-PIM need to be 758 established. 760 4.4.1. Routing Information Base for BIDIR-PIM 762 In this scenario, BIDIR-PIM will rely on a Multicast Routing 763 Information Base (MRIB) that is generated independently of the 764 policy-based routing rules of PMIPv6. The following information is 765 needed. 767 o All routes to networks and nodes (including RPAs) that are not 768 mobile members of the PMIPv6 domain MUST be defined consistently 769 among BIDIR-PIM routers and remain unaffected by node mobility. 770 The setup of these general routes is expected to follow the 771 topology of the operator network and is beyond the scope of this 772 document. 774 4.4.2. Operations of BIDIR-PIM 776 BIDIR-PIM will establish spanning trees across its network domain in 777 conformance to its pre-configured RPAs and the routing information 778 provided. Multicast data transmitted by a mobile source will 779 immediately be forwarded by its DF (MAG) onto the spanning tree for 780 the multicast group without further protocol operations. 782 On handover, the mobile source reattaches to a new MAG (DF), which 783 completes unicast network configurations. Thereafter, the source can 784 immediately proceed with multicast packet transmission onto the pre- 785 established distribution tree. BIDIR-PIM does neither require 786 protocol signaling nor additional reconfiguration delays to adapt to 787 source mobility and can be considered the protocol of choice for 788 mobile multicast operations in the access. As multicast streams 789 always flow up to the Rendezvous Point Link, some care should be 790 taken to configure RPAs compliant with network capacities. 792 5. MLD Proxy Peering Function for Optimized Source Mobility in PMIPv6 794 A deployment of MLD Proxies (see [RFC4605]) at MAGs has proven a 795 useful and appropriate approach to multicast in PMIPv6, see 796 [RFC6224], [RFC7028]. However, deploying unmodified standard proxies 797 can go along with significant performance degradation for mobile 798 senders as discussed along the lines of this document. To overcome 799 these deficits, an optimized approach to multicast source mobility 800 based on extended peering functions among proxies is defined in this 801 section. Based on such direct data exchange between proxy instances 802 at MAGs, triangular routing is avoided and multicast streams can be 803 disseminated directly within a PMIPv6 access network, and in 804 particular within MAG routing machines. Prior to presenting the 805 solution, we will summarize the relevant requirements. 807 5.1. Requirements 809 Solutions that extend MLD Proxies by additional uplinking functions 810 need to comply to the following requirements. 812 Prevention of Routing Loops In the absence of a full-featured 813 routing logic at an MLD Proxy, simple and locally decidable rules 814 need to prevent source traffic from traversing the network in 815 loops as potentially enabled by multiple uplinks. 817 Unique coverage of receivers Listener functions at Proxies require 818 simple, locally decidable rules to initiate a unique delivery of 819 multicast packets to all receivers. 821 Following local filter techniques, these requirements are met in the 822 following solution. 824 5.2. Overview 826 A peering interface for MLD proxies allows for a direct data exchange 827 of locally attached multicast sources. Such peering interfaces can 828 be configured - as a direct link or a bidirectional tunnel - between 829 any two proxy instances (locally deployed as in [RFC6224] or 830 remotely). Peerings remain as silent virtual links in regular proxy 831 operations. Data is exchanged on such links only in cases, where one 832 peering proxy on its downstream directly connects to a source of 833 multicast traffic, which the other peering proxy actively subscribes 834 to. In such cases, the proxy connected to the source will receive a 835 listener report on its peering interface and forwards traffic from 836 its local source accordingly. It is worth noting that multicast 837 traffic distribution on peering links does not follow reverse unicast 838 paths to sources. In the following, operations are defined for ASM 839 and SSM, but provide superior performance in the presence of source- 840 specific signaling (IGMPv3/MLDv2) [RFC4604]. 842 5.3. Operations in Support of Multicast Senders 844 An MLD proxy in the perspective of a sender will see peering 845 interfaces as restricted downstream interfaces. It will install and 846 maintain source filters at its peering links that will restrict data 847 transmission to those packets that originate from a source that is 848 locally attached at one of its downstream interfaces. 850 In detail, a proxy will extract from its configuration the network 851 prefixes attached to its downstream interfaces and MUST implement a 852 source filter base at its peering interfaces that restricts data 853 transmission to IP source addresses from its local prefixes. This 854 filter base MUST be updated, if and only if the downstream 855 configuration changes (e.g., due to mobility). Multicast packets 856 that arrive from the upstream interface of the proxy are thus 857 prevented from traversing any peering link, but are only forwarded to 858 regular downstream interfaces with appropriate subscription states. 859 In this way, a multihop forwarding on peering links is prevented. 861 Multicast traffic arriving from a locally attached source will be 862 forwarded to the regular upstream interface and all downstreams with 863 appropriate subscription states (i.e., regular proxy operations). In 864 addition, multicast packets of local origin are transferred to those 865 peering interfaces with appropriate subscription states. 867 5.4. Operations in Support of Multicast Listeners 869 At the listener side, peering interfaces appear as preferred upstream 870 links. The multicast proxy will attempt to receive multicast 871 services on peering links for as many groups (channels) as possible. 872 The general upstream interface configured according to [RFC4605] will 873 be used only for retrieving those groups (channels) that remain 874 unavailable from peerings. From this extension of [RFC4605], an MLD 875 proxy with peering interconnects will exhibit several interfaces for 876 pulling remote traffic: the regular upstream and the peerings. 877 Traffic available from any of the peering links will be mutually 878 disjoint, but normally also available from the upstream. To prevent 879 duplicate traffic from arriving at the listener side, the proxy 881 o MAY delay aggregated reports to the upstream, and 883 o MUST apply appropriate filters to exclude duplicate streams. 885 In detail, an MLD proxy instance at a MAG first issues listener 886 reports (in parallel) to all of its peering links. These links span 887 at most one (virtual) hop. Whenever certain group traffic (SSM 888 channels) does not arrive from the peerings after a waiting time 889 (default: 10 ms (node-local) and 25 ms (remote)), additional 890 (complementary, in the case of SSM) reports are sent to the standard 891 upstream interface. 893 Whenever traffic from a peering link arrives, an MLD proxy MUST 894 install source filters at its RFC 4605 upstream in the following way. 896 ASM with IGMPv2/MLDv1 In the presence of Any Source Multicast using 897 IGMPv2/MLDv1, only, the proxy cannot signal source filtering to 898 its upstream. Correspondingly, it applies (S,*) ingress filters 899 at its upstream interface for all sources S seen in traffic on the 900 peering links. It is noteworthy that unwanted traffic is still 901 replicated to the proxy via the (wired) provider backbone, but it 902 is not forwarded into the wireless access network. 904 ASM with IGMPv3/MLDv2 In the presence of source-specific signaling 905 (IGMPv3/MLDv2), the upstream interface is set to (S,*) exclude 906 mode for all sources S seen in traffic of the peering links. The 907 corresponding source-specific signaling will prevent forwarding of 908 duplicate traffic throughout the access network. 910 SSM In the presence of Source Specific Multicast, the proxy will 911 subscribe on its uplink interface to those (S,G) channels, only, 912 that do not arrive via the peering links. 914 MLD proxies will install data-driven timers (source-timeout) for each 915 source but common to all peering interfaces to detect interruptions 916 of data services from individual sources at proxy peers. Termination 917 of source-specific flows may be application-specific, but also due to 918 a source handover, or transmission failures. After a handover, a 919 mobile source may reattach at another MLD proxy with peering relation 920 to the listener, or at a proxy that does not peer. While in the 921 first case, traffic reappears on another peering link, in the second 922 case data can only be retrieved via the regular upstream. To account 923 for the latter, the MLD proxy revokes the source-specific filter(s) 924 at its upstream interface, after the source-timeout fires (default: 925 50 ms). Corresponding traffic will then be pulled from the regular 926 upstream. Source-specific filters MUST be reinstalled, whenever 927 traffic of this source arrives at any peering interface. 929 There is a noteworthy trade-off between traffic minimization and 930 available traffic at the upstream that is locally filtered at the 931 proxy. Implementors can use this relation to optimize for service- 932 specific requirements. 934 In proceeding this way, multicast group data will arrive from peering 935 interfaces first, while only peer-wise unavailable traffic is 936 retrieved from the regular upstream interface. 938 6. IANA Considerations 940 This document makes no request to IANA.. 942 Note to RFC Editor: this section may be removed on publication as an 943 RFC. 945 7. Security Considerations 947 This document defines multicast sender mobility based on PMIPv6 and 948 common multicast routing protocols. Consequently, threats identified 949 as security concerns of [RFC2236], [RFC2710], , [RFC3810], [RFC4605], 950 [RFC5213], and [RFC5844] are inherited by this document. 952 In addition, particular attention should be paid to implications of 953 combining multicast and mobility management at network entities. As 954 this specification allows mobile nodes to initiate the creation of 955 multicast forwarding states at MAGs and LMAs while changing 956 attachments, threats of resource exhaustion at PMIP routers and 957 access networks arrive from rapid state changes, as well as from high 958 volume data streams routed into access networks of limited 959 capacities. In cases of PIM-SM deployment, handover operations of 960 the MNs include re-registering sources at the Rendezvous Points at 961 possibly high frequency. In addition to proper authorization checks 962 of MNs, rate controls at routing agents and replicators MAY be 963 required to protect the agents and the downstream networks. In 964 particular, MLD proxy implementations at MAGs SHOULD carefully 965 procure for automatic multicast state extinction on the departure of 966 MNs, as mobile multicast listeners in the PMIPv6 domain will in 967 general not actively terminate group membership prior to departure. 969 The deployment of IGMP/MLD proxies for multicast routing requires 970 particular care, as routing loops on the upstream are not 971 automatically detected. Peering functions between proxies extend 972 this threat in the following way. Routing loops among peering and 973 upstream interfaces are prevented by filters on local sources. Such 974 filtering can fail, whenever prefix configurations for downstream 975 interfaces at a proxy are incorrect or inconsistent. Consequently, 976 implementations of peering-enabled proxies SHOULD take particular 977 care on maintaining (varying) IP configurations at the downstream in 978 a reliable and timely manner (see [RFC6224] for requirements on 979 PMIPv6-compliant implementations of MLD proxies). 981 8. Acknowledgements 983 The authors would like to thank (in alphabetical order) David Black, 984 Luis M. Contreras, Muhamma Omer Farooq, Bohao Feng, Sri Gundavelli, 985 Dirk von Hugo, Ning Kong, Jouni Korhonen, He-Wu Li, Cong Liu, Akbar 986 Rahman, Behcet Sarikaya, Stig Venaas, Li-Li Wang, Sebastian Woelke, 987 Qian Wu, Zhi-Wei Yan for advice, help and reviews of the document. 988 Funding by the German Federal Ministry of Education and Research 989 within the G-LAB Initiative (projects HAMcast, Mindstone and SAFEST) 990 is gratefully acknowledged. 992 9. References 994 9.1. Normative References 996 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 997 Requirement Levels", BCP 14, RFC 2119, March 1997. 999 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1000 Listener Discovery (MLD) for IPv6", RFC 2710, October 1001 1999. 1003 [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. 1004 Thyagarajan, "Internet Group Management Protocol, Version 1005 3", RFC 3376, October 2002. 1007 [RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery 1008 Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. 1010 [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, 1011 "Protocol Independent Multicast - Sparse Mode (PIM-SM): 1012 Protocol Specification (Revised)", RFC 4601, August 2006. 1014 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 1015 "Internet Group Management Protocol (IGMP) / Multicast 1016 Listener Discovery (MLD)-Based Multicast Forwarding ("IGMP 1017 /MLD Proxying")", RFC 4605, August 2006. 1019 [RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano, 1020 "Bidirectional Protocol Independent Multicast (BIDIR- 1021 PIM)", RFC 5015, October 2007. 1023 [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., 1024 and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 1026 [RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy 1027 Mobile IPv6", RFC 5844, May 2010. 1029 [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support 1030 in IPv6", RFC 6275, July 2011. 1032 9.2. Informative References 1034 [I-D.ietf-multimob-fmipv6-pfmipv6-multicast] 1035 Schmidt, T., Waehlisch, M., Koodli, R., Fairhurst, G., and 1036 D. Liu, "Multicast Listener Extensions for MIPv6 and 1037 PMIPv6 Fast Handovers", draft-ietf-multimob- 1038 fmipv6-pfmipv6-multicast-03 (work in progress), February 1039 2014. 1041 [I-D.ietf-multimob-handover-optimization] 1042 Contreras, L., Bernardos, C., and I. Soto, "PMIPv6 1043 multicast handover optimization by the Subscription 1044 Information Acquisition through the LMA (SIAL)", draft- 1045 ietf-multimob-handover-optimization-07 (work in progress), 1046 December 2013. 1048 [RFC2236] Fenner, W., "Internet Group Management Protocol, Version 1049 2", RFC 2236, November 1997. 1051 [RFC4604] Holbrook, H., Cain, B., and B. Haberman, "Using Internet 1052 Group Management Protocol Version 3 (IGMPv3) and Multicast 1053 Listener Discovery Protocol Version 2 (MLDv2) for Source- 1054 Specific Multicast", RFC 4604, August 2006. 1056 [RFC5757] Schmidt, T., Waehlisch, M., and G. Fairhurst, "Multicast 1057 Mobility in Mobile IP Version 6 (MIPv6): Problem Statement 1058 and Brief Survey", RFC 5757, February 2010. 1060 [RFC5845] Muhanna, A., Khalil, M., Gundavelli, S., and K. Leung, 1061 "Generic Routing Encapsulation (GRE) Key Option for Proxy 1062 Mobile IPv6", RFC 5845, June 2010. 1064 [RFC6224] Schmidt, T., Waehlisch, M., and S. Krishnan, "Base 1065 Deployment for Multicast Listener Support in Proxy Mobile 1066 IPv6 (PMIPv6) Domains", RFC 6224, April 2011. 1068 [RFC7028] Zuniga, JC., Contreras, LM., Bernardos, CJ., Jeon, S., and 1069 Y. Kim, "Multicast Mobility Routing Optimizations for 1070 Proxy Mobile IPv6", RFC 7028, September 2013. 1072 Appendix A. Multiple Upstream Interface Proxy 1074 In this section, we document upstream extensions for an MLD proxy 1075 that were originally developed during the work on this document. 1076 Multiple proxy instances deployed at a single MAG (see Section 3) can 1077 be avoided by adding multiple upstream interfaces to a single MLD 1078 Proxy. In a typical PMIPv6 deployment, each upstream of a single 1079 proxy instance can interconnect to one of the LMAs. With such 1080 ambiguous upstream options, appropriate forwarding rules MUST be 1081 supplied to 1083 o unambiguously guide traffic forwarding from directly attached 1084 mobile sources, and 1086 o lead listener reports to initiating unique traffic subscriptions. 1088 This can be achieved by a complete set of source- and group-specific 1089 filter rules (e.g., (S,*), (*,G)) installed at proxy interfaces. 1090 These filters MAY be derived in parts from PMIPv6 routing policies, 1091 and can include a default behavior (e.g., (*,*)). 1093 A.1. Operations for Local Multicast Sources 1095 Packets from a locally attached multicast source will be forwarded to 1096 all downstream interfaces with appropriate subscriptions, as well as 1097 up the interface with the matching source-specific filter. 1099 Typically, the upstream interface for a mobile multicast source is 1100 chosen based on the policy routing (e.g., the MAG-LMA tunnel 1101 interface for LMA-based routing or the interface towards the 1102 multicast router for direct routing), but alternate configurations 1103 MAY be applied. Packets from a locally attached multicast source 1104 will be forwarded to the corresponding upstream interface with the 1105 matching source-specific filter, as well as all the downstream 1106 interfaces with appropriate subscriptions. 1108 A.2. Operations for Local Multicast Subscribers 1110 Multicast listener reports are group-wise aggregated by the MLD 1111 proxy. The aggregated report is issued to the upstream interface 1112 with matching group/channel-specific filter. The choice of the 1113 corresponding upstream interface for aggregated group membership 1114 reports MAY be additionally based on some administrative scoping 1115 rules for scoped multicast group addresses. 1117 In detail, a Multiple Upstream Interface proxy will provide and 1118 maintain a Multicast Subscription Filter Table that maps source- and 1119 group-specific filters to upstream interfaces. The forwarding 1120 decision for an aggregated MLD listener report is based on the first 1121 matching entry from this table, with the understanding that for 1122 IGMPv3/MLDv2 the MLD proxy performs a state decomposition, if needed 1123 (i.e., a (*,G) subscription is split into (S,G) and (* \ S,G) in the 1124 presence of (*,G) after (S,G) interface entries), and that 1125 (S,*)-filters are always false in the absence of source-specific 1126 signaling, i.e. in IGMPv2/MLDv1 only domains. 1128 In typical deployment scenarios, specific group services (channels) 1129 could be either associated with selected uplinks to remote LMAs, 1130 while a (*,*) default subscription entry (in the last table line) is 1131 bound to a local routing interface, or selected groups are configured 1132 as local services first, while a (*,*) default entry (in the last 1133 table line) points to a remote uplink that provides the general 1134 multicast support. 1136 Appendix B. Implementation 1138 An implementation of the extended IGMP/MLD proxy has been provided 1139 within the MCPROXY project http://mcproxy.realmv6.org/. This open 1140 source software is written in C++ and uses forwarding capabilities of 1141 the Linux kernel. It supports all regular operations according to 1142 [RFC4605], allows for multiple proxy instances on one node, 1143 dynamically changing downstream links, as well as proxy-to-proxy 1144 peerings and multiple upstream links with individual configurations. 1145 The software can be downloaded from Github at https://github.com/ 1146 mcproxy/mcproxy. 1148 Appendix C. Change Log 1150 The following changes have been made from version draft-ietf- 1151 multimob-pmipv6-source-06: 1153 1. Editorial improvements in response to WG Last Call. 1155 2. Clarified mobile source handover treatment for peering proxies in 1156 response to WG Last Call. 1158 3. Updated and extended references. 1160 4. Added pointer to available implementation in Appendix. 1162 The following changes have been made from version draft-ietf- 1163 multimob-pmipv6-source-05: 1165 1. Editorial improvements in response to WG feedback. 1167 2. Updated and extended references. 1169 The following changes have been made from version draft-ietf- 1170 multimob-pmipv6-source-04: 1172 1. Cleaned structure in Section Section 5. 1174 2. Clarified operations of the proxy peering function. 1176 3. Completed Section on Security Considerations. 1178 4. Editorial improvements in response to WG feedback. 1180 5. Updated and extended references. 1182 The following changes have been made from version draft-ietf- 1183 multimob-pmipv6-source-03: 1185 1. Fixed issues in Section Section 4.3 (PIM phase two and three 1186 transition) according to WG feedback. 1188 2. Editorial improvements, resolved nits. 1190 3. Updated references. 1192 The following changes have been made from version draft-ietf- 1193 multimob-pmipv6-source-02: 1195 1. Added clarifications and details as requested by the working 1196 group, resolved nits. 1198 2. Moved Multiple Upstream MLD proxy to Appendix in response to WG 1199 desire. 1201 3. Updated references. 1203 The following changes have been made from version draft-ietf- 1204 multimob-pmipv6-source-01: 1206 1. Added clarifications and details as requested by the working 1207 group, resolved nits. 1209 2. Detailed out operations of Multiple Upstream MLD Proxies. 1211 3. Clarified operations of MLD proxies with peering links. 1213 4. Many editorial improvements. 1215 5. Updated references. 1217 The following changes have been made from version draft-ietf- 1218 multimob-pmipv6-source-00: 1220 1. Direct routing with PIM-SM and PIM-SSM has been added. 1222 2. PMIP synchronization with PIM added for improved handover. 1224 3. Direct routing with BIDIR-PIM has been added. 1226 4. MLD proxy extensions requirements added. 1228 5. Peering of MLD Proxies added. 1230 6. First sketch of multiple upstream proxy added. 1232 7. Editorial improvements. 1234 8. Updated references. 1236 Authors' Addresses 1238 Thomas C. Schmidt (editor) 1239 HAW Hamburg 1240 Berliner Tor 7 1241 Hamburg 20099 1242 Germany 1244 Email: schmidt@informatik.haw-hamburg.de 1245 URI: http://inet.cpt.haw-hamburg.de/members/schmidt 1247 Shuai Gao 1248 Beijing Jiaotong University 1249 Beijing 1250 China 1252 Email: shgao@bjtu.edu.cn 1254 Hong-Ke Zhang 1255 Beijing Jiaotong University 1256 Beijing 1257 China 1259 Email: hkzhang@bjtu.edu.cn 1260 Matthias Waehlisch 1261 link-lab & FU Berlin 1262 Hoenower Str. 35 1263 Berlin 10318 1264 Germany 1266 Email: mw@link-lab.net