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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: 'RFC2710' is defined on line 421, but no explicit reference was found in the text == Unused Reference: 'RFC2236' is defined on line 448, but no explicit reference was found in the text ** Obsolete normative reference: RFC 3775 (Obsoleted by RFC 6275) Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MULTIMOB Group T C. Schmidt 3 Internet-Draft HAW Hamburg 4 Intended status: Informational M. Waehlisch 5 Expires: September 29, 2011 link-lab & FU Berlin 6 M. Farooq 7 HAW Hamburg 8 March 28, 2011 10 Mobile Multicast Sender Support in PMIPv6 Domains with Base Multicast 11 Deployment 12 draft-schmidt-multimob-pmipv6-base-source-00 14 Abstract 16 Multicast communication can be enabled in Proxy Mobile IPv6 domains 17 by deploying MLD Proxy functions at Mobile Access Gateways, and 18 multicast routing functions at Local Mobility Anchors. This document 19 describes the support of mobile multicast senders in Proxy Mobile 20 IPv6 domains that is provided by this base deployment scenario. 21 Mobile sources remain agnostic of multicast mobility operations. 23 Requirements Language 25 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 26 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 27 document are to be interpreted as described in RFC 2119 [RFC2119]. 29 Status of this Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at http://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on September 29, 2011. 46 Copyright Notice 48 Copyright (c) 2011 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 64 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 66 4. Source Mobility Details . . . . . . . . . . . . . . . . . . . 7 67 4.1. Operations of the Mobile Node . . . . . . . . . . . . . . 7 68 4.2. Operations of the Mobile Access Gateway . . . . . . . . . 7 69 4.3. Operations of the Local Mobility Anchor . . . . . . . . . 7 70 4.4. IPv4 Support . . . . . . . . . . . . . . . . . . . . . . . 7 71 4.5. Efficiency of the Distribution System . . . . . . . . . . 8 72 4.6. Multicast Availability throughout the Access Network . . . 9 73 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 74 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 75 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 76 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 77 8.1. Normative References . . . . . . . . . . . . . . . . . . . 10 78 8.2. Informative References . . . . . . . . . . . . . . . . . . 11 79 Appendix A. Evaluation of Traffic Flows . . . . . . . . . . . . . 11 80 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 11 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 83 1. Introduction 85 Proxy Mobile IPv6 (PMIPv6) [RFC5213] extends Mobile IPv6 (MIPv6) 86 [RFC3775] by network-based management functions that enable IP 87 mobility for a host without requiring its participation in any 88 mobility-related signaling. Additional network entities called the 89 Local Mobility Anchor (LMA), and Mobile Access Gateways (MAGs), are 90 responsible for managing IP mobility on behalf of the mobile node 91 (MN). An MN connected to a PMIPv6 domain, which only operates 92 according to the base specifications of [RFC5213], cannot participate 93 in multicast communication, as MAGs will discard group packets. 95 Multicast support for mobile listeners can be enabled within a PMIPv6 96 domain by deploying MLD Proxy functions at Mobile Access Gateways, 97 and multicast routing functions at Local Mobility Anchors 98 [I-D.ietf-multimob-pmipv6-base-solution]. This base deployment 99 option is the simplest way to PMIPv6 multicast extensions in the 100 sense that it neither requires new protocol operations nor additional 101 infrastructure entities. Standard software functions need to be 102 activated on PMIPv6 entities, only, on the price of possibly non- 103 optimal multicast routing. 105 This document describes the support of mobile multicast senders in 106 Proxy Mobile IPv6 domains as it is provided by the base deployment 107 scenario [I-D.ietf-multimob-pmipv6-base-solution]. Mobile Nodes in 108 this setting remain agnostic of multicast mobility operations. This 109 document discusses implications on multicast routing, but does not 110 address specific optimizations and efficiency improvements of 111 multicast routing for network-based mobility as discussed in 112 [RFC5757]. 114 2. Terminology 116 This document uses the terminology as defined for the mobility 117 protocols [RFC3775], [RFC5213] and [RFC5844], as well as the 118 multicast edge related protocols [RFC3376], [RFC3810] and [RFC4605]. 120 3. Overview 122 The reference scenario for multicast deployment in Proxy Mobile IPv6 123 domains is illustrated in Figure 1. 125 +-------------+ 126 | Multicast | 127 | Listeners | 128 +-------------+ 129 | 130 *** *** *** *** 131 * ** ** ** * 132 * * 133 * Fixed Internet * 134 * * 135 * ** ** ** * 136 *** *** *** *** 137 / \ 138 +----+ +----+ 139 |LMA1| |LMA2| Multicast Anchor 140 +----+ +----+ 141 LMAA1 | | LMAA2 142 | | 143 \\ //\\ 144 \\ // \\ 145 \\ // \\ Unicast Tunnel 146 \\ // \\ 147 \\ // \\ 148 \\ // \\ 149 Proxy-CoA1 || || Proxy-CoA2 150 +----+ +----+ 151 |MAG1| |MAG2| MLD Proxy 152 +----+ +----+ 153 | | | 154 MN-HNP1 | | MN-HNP2 | MN-HNP3 155 MN1 MN2 MN3 156 Multicast Sender + Listener(s) 158 Figure 1: Reference Network for Multicast Deployment in PMIPv6 with 159 Source Mobility 161 An MN in a PMIPv6 domain will decide on multicast data transmission 162 completely independent of its current mobility conditions. It will 163 send packets as initiated by applications, using its source address 164 with Home Network Prefix (HNP) and a multicast destination addresses 165 chosen by application needs. Multicast packets will arrive at the 166 currently active MAG via one of its downstream local (wireless) 167 links. A multicast unaware MAG would simply discard these packets in 168 the absence of a multicast forwarding information base (MFIB). 170 An MN can successfully distribute multicast data in PMIPv6, if MLD 171 proxy functions are deployed at the MAG as described in 172 [I-D.ietf-multimob-pmipv6-base-solution]. In this set-up, the MLD 173 proxy instance serving a mobile multicast source has configured its 174 upstream interface at the tunnel towards MN's corresponding LMA. For 175 each LMA, there will be a separate instance of an MLD proxy. 177 According to the specifications given in [RFC4605], multicast data 178 arriving from a downstream interface of an MLD proxy will be 179 forwarded to the upstream interface and to all but the incoming 180 downstream interfaces with appropriate forwarding states for this 181 group. Thus multicast streams originating from an MN will arrive at 182 the corresponding LMA and directly at all mobile receivers co-located 183 at the same MAG. Serving as the designated multicast router or an 184 additional MLD proxy, the LMA forwards data to the fixed Internet, if 185 forwarding states are maintained through multicast routing. If the 186 LMA is acting as another MLD proxy, it will forward the multicast 187 data to its upstream interface, and based upon the downstream 188 interfaces' subscriptions accordingly. 190 In case of a handover, the MN (unaware of IP mobility) can continue 191 to send multicast packets as soon as network connectivity is 192 reconfigured. At this time, the MAG has determined the corresponding 193 LMA, and IPv6 unicast address configuration with PMIPv6 bindings have 194 been performed. Multicast packets arriving at the MAG are discarded 195 until the MAG has completed the following steps. 197 1. The MAG SHOULD determine whether the MN is admissible to 198 multicast services, and stop here otherwise. 200 2. The MAG adds the new downstream link to the MLD proxy instance 201 with up-link to the corresponding LMA. 203 As soon as the MN's uplink is associated with the corresponding MLD 204 proxy instance, multicast packets are forwarded again to the LMA and 205 eventually to receivers within the PMIP domain (see the call flow in 206 Figure 2). In this way, multicast source mobility is transparently 207 enabled in PMIPv6 domains that deploy the base scenario for 208 multicast. 210 MN1 MAG1 MN2 MAG2 LMA 211 | | | | | 212 | | Mcast Data | | | 213 | |<---------------+ | | 214 | | Mcast Data | | | 215 | Join(G) +================================================>| 216 +--------------> | | | | 217 | Mcast Data | | | | 218 |<---------------+ | | | 219 | | | | | 220 | < Movement of MN 2 to MAG2 & PMIP Binding Update > | 221 | | | | | 222 | | |--- Rtr Sol -->| | 223 | | |<-- Rtr Adv ---| | 224 | | | | | 225 | | | < MLD Proxy Configuration > | 226 | | | | | 227 | | | MLD Query | | 228 | | |<--------------+ | 229 | | | Mcast Data | | 230 | | +-------------->| | 231 | | | | Mcast Data | 232 | | | +===============>| 233 | | | | | 234 | | Mcast Data | | | 235 | |<================================================+ 236 | Mcast Data | | | | 237 |<---------------+ | | | 238 | | | | | 240 Figure 2: Call Flow for Group Communication in Multicast-enabled PMIP 242 These multicast deployment considerations likewise apply for mobile 243 nodes that operate with their IPv4 stack enabled in a PMIPv6 domain. 244 PMIPv6 can provide IPv4 home address mobility support [RFC5844]. 245 IPv4 multicast is handled by an IGMP proxy function at the MAG in an 246 analogous way. 248 Following these deployment steps, multicast traffic distribution 249 transparently inter-operates with PMIPv6. It is worth noting that a 250 MN - while being attached to the same MAG as the mobile source, but 251 associated with a different LMA, cannot receive multicast traffic on 252 a shortest path. Instead, multicast streams flow up to the LMA of 253 the mobile source, are transferred to the LMA of the mobile listener 254 and tunneled downwards to the MAG again (see Appendix A for further 255 considerations). 257 4. Source Mobility Details 259 Incorporating multicast source mobility in PMIPv6 requires to deploy 260 general multicast functions at PMIPv6 routers and to define their 261 interaction with the PMIPv6 protocol in the following way. 263 4.1. Operations of the Mobile Node 265 A Mobile Node willing to send multicast data will proceed as if 266 attached to the fixed Internet. No specific mobility or other 267 multicast related functionalities are required at the MN. 269 4.2. Operations of the Mobile Access Gateway 271 A Mobile Access Gateway is required to have MLD proxy instances 272 deployed corresponding to each LMA, taking the corresponding tunnel 273 as its unique upstream link, cf., 274 [I-D.ietf-multimob-pmipv6-base-solution]. On the arrival of a MN, 275 the MAG decides on the mapping of downstream links to a proxy 276 instance and the upstream link to the LMA based on the regular 277 Binding Update List as maintained by PMIPv6 standard operations. 278 When multicast data is received from the MN, the MAG MUST identify 279 the corresponding proxy instance from the incoming interface and 280 forwards multicast data upstream according to [RFC4605]. 282 The MAG MAY apply special admission control to enable multicast data 283 transition from a MN. It is advisable to take special care that MLD 284 proxy implementations do not redistribute multicast data to 285 downstream interfaces without appropriate subscriptions in place. 287 4.3. Operations of the Local Mobility Anchor 289 For any MN, the Local Mobility Anchor acts as the persistent Home 290 Agent and at the same time as the default multicast upstream for the 291 corresponding MAG. It will manage and maintain a multicast 292 forwarding information base for all group traffic arriving from its 293 mobile sources. It SHOULD participate in multicast routing functions 294 that enable traffic redistribution to all adjacent LMAs within the 295 PMIPv6 domain and thereby ensure a continuous receptivity while the 296 source is in motion. 298 4.4. IPv4 Support 300 An MN in a PMIPv6 domain may use an IPv4 address transparently for 301 communication as specified in [RFC5844]. For this purpose, LMAs can 302 register IPv4-Proxy-CoAs in its Binding Caches and MAGs can provide 303 IPv4 support in access networks. Correspondingly, multicast 304 membership management will be performed by the MN using IGMP. For 305 multicast support on the network side, an IGMP proxy function needs 306 to be deployed at MAGs in exactly the same way as for IPv6. 307 [RFC4605] defines IGMP proxy behaviour in full agreement with IPv6/ 308 MLD. Thus IPv4 support can be transparently provided following the 309 obvious deployment analogy. 311 For a dual-stack IPv4/IPv6 access network, the MAG proxy instances 312 SHOULD choose multicast signaling according to address configurations 313 on the link, but MAY submit IGMP and MLD queries in parallel, if 314 needed. It should further be noted that the infrastructure cannot 315 identify two data streams as identical when distributed via an IPv4 316 and IPv6 multicast group. Thus duplicate data may be forwarded on a 317 heterogeneous network layer. 319 A particular note is worth giving the scenario of [RFC5845] in which 320 overlapping private address spaces of different operators can be 321 hosted in a PMIP domain by using GRE encapsulation with key 322 identification. This scenario implies that unicast communication in 323 the MAG-LMA tunnel can be individually identified per MN by the GRE 324 keys. This scenario still does not impose any special treatment of 325 multicast communication for the following reasons. 327 Multicast streams from and to MNs arrive at a MAG on point-to-point 328 links (identical to unicast). between the routers and independent of 329 any individual MN. So the MAG-proxy and the LMA SHOULD NOT use GRE 330 key identifiers, but plain GRE encapsulation in multicast 331 communication (including MLD queries and reports). Multicast traffic 332 sent upstream and downstream of MAG-to-LMA tunnels proceeds as 333 router-to-router forwarding according to the multicast forwarding 334 information base (MFIB) of the MAG or LMA and independent of MN's 335 unicast addresses, while the MAG proxy instance re-distributes 336 multicast data down the point-to-point links (interfaces) according 337 to its own MFIB, independent of MN's IP addresses. 339 4.5. Efficiency of the Distribution System 341 In the following efficiency-related issues are enumerated. 343 Multicast reception at LMA In the current deployment scenario, the 344 LMA will receive all multicast traffic originating from its 345 associated MNs. There is no mechanism to suppress upstream 346 forwarding in the absence of receivers. 348 MNs on the same MAG using different LMAs For a mobile receiver and a 349 source that use different LMAs, the traffic has to go up to one 350 LMA, cross over to the other LMA, and then be tunneled back to the 351 same MAG, causing redundant flows in the access network and at the 352 MAG. 354 4.6. Multicast Availability throughout the Access Network 356 There may be deployment scenarios, where multicast services are 357 available throughout the access network independent of the PMIPv6 358 infrastructure. Direct multicast access at MAGs may be supported 359 through native multicast routing within a flat access network that 360 includes a multicast router, via dedicated (tunnel or VPN) links 361 between MAGs and designated multicast routers. 363 Multicast traffic distribution can be simplified in these scenarios. 364 A single proxy instance at MAGs with up-link into the multicast cloud 365 will serve as a first hop gateway into the multicast routing domain 366 and avoid traffic duplication or detour routing. However, mobility 367 of the multicast source in this scenario will require some multicast 368 routing protocols to rebuild distribution trees. This can cause 369 significant service disruptions or delays (see [RFC5757] for further 370 details). 372 5. IANA Considerations 374 This document makes no request of IANA. 376 Note to RFC Editor: this section may be removed on publication as an 377 RFC. 379 6. Security Considerations 381 This draft does not introduce additional messages or novel protocol 382 operations. Consequently, no new threats are introduced by this 383 document in addition to those identified as security concerns of 384 [RFC3810], [RFC4605], [RFC5213], and [RFC5844]. 386 However, particular attention should be paid to implications of 387 combining multicast and mobility management at network entities. As 388 this specification allows mobile nodes to initiate the creation of 389 multicast forwarding states at MAGs and LMAs while changing 390 attachments, threats of resource exhaustion at PMIP routers and 391 access networks arrive from rapid state changes, as well as from high 392 volume data streams routed into access networks of limited 393 capacities. In addition to proper authorization checks of MNs, rate 394 controls at replicators MAY be required to protect the agents and the 395 downstream networks. In particular, MLD proxy implementations at 396 MAGs SHOULD carefully procure for automatic multicast state 397 extinction on the departure of MNs, as mobile multicast listeners in 398 the PMIPv6 domain will not actively terminate group membership prior 399 to departure. 401 7. Acknowledgements 403 The authors would like to thank (in alphabetical order) Jouni 404 Korhonen and Stig Venaas for advice, help and reviews of the 405 document. Funding by the German Federal Ministry of Education and 406 Research within the G-LAB Initiative is gratefully acknowledged. 408 8. References 410 8.1. Normative References 412 [I-D.ietf-multimob-pmipv6-base-solution] 413 Schmidt, T., Waehlisch, M., and S. Krishnan, "Base 414 Deployment for Multicast Listener Support in PMIPv6 415 Domains", draft-ietf-multimob-pmipv6-base-solution-07 416 (work in progress), December 2010. 418 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 419 Requirement Levels", BCP 14, RFC 2119, March 1997. 421 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 422 Listener Discovery (MLD) for IPv6", RFC 2710, 423 October 1999. 425 [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. 426 Thyagarajan, "Internet Group Management Protocol, Version 427 3", RFC 3376, October 2002. 429 [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support 430 in IPv6", RFC 3775, June 2004. 432 [RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery 433 Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. 435 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 436 "Internet Group Management Protocol (IGMP) / Multicast 437 Listener Discovery (MLD)-Based Multicast Forwarding 438 ("IGMP/MLD Proxying")", RFC 4605, August 2006. 440 [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., 441 and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 443 [RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy 444 Mobile IPv6", RFC 5844, May 2010. 446 8.2. Informative References 448 [RFC2236] Fenner, W., "Internet Group Management Protocol, Version 449 2", RFC 2236, November 1997. 451 [RFC5757] Schmidt, T., Waehlisch, M., and G. Fairhurst, "Multicast 452 Mobility in Mobile IP Version 6 (MIPv6): Problem Statement 453 and Brief Survey", RFC 5757, February 2010. 455 [RFC5845] Muhanna, A., Khalil, M., Gundavelli, S., and K. Leung, 456 "Generic Routing Encapsulation (GRE) Key Option for Proxy 457 Mobile IPv6", RFC 5845, June 2010. 459 Appendix A. Evaluation of Traffic Flows 461 TODO 463 Appendix B. Change Log 465 Authors' Addresses 467 Thomas C. Schmidt 468 HAW Hamburg 469 Berliner Tor 7 470 Hamburg 20099 471 Germany 473 Email: schmidt@informatik.haw-hamburg.de 474 URI: http://inet.cpt.haw-hamburg.de/members/schmidt 476 Matthias Waehlisch 477 link-lab & FU Berlin 478 Hoenower Str. 35 479 Berlin 10318 480 Germany 482 Email: mw@link-lab.net 483 Muhamma Omer Farooq 484 HAW Hamburg 485 Berliner Tor 7 486 Hamburg 20099 487 Germany 489 Email: omer.farooq@ymail.com