idnits 2.17.1 draft-bernardos-dmm-pmip-04.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 5, 2015) is 3340 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-09) exists of draft-bernardos-dmm-distributed-anchoring-04 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DMM Working Group CJ. Bernardos 3 Internet-Draft A. de la Oliva 4 Intended status: Standards Track F. Giust 5 Expires: September 6, 2015 UC3M 6 March 5, 2015 8 A PMIPv6-based solution for Distributed Mobility Management 9 draft-bernardos-dmm-pmip-04 11 Abstract 13 The number of mobile users and their traffic demand is expected to be 14 ever-increasing in future years, and this growth can represent a 15 limitation for deploying current mobility management schemes that are 16 intrinsically centralized, e.g., Mobile IPv6 and Proxy Mobile IPv6. 17 For this reason it has been waved a need for distributed and dynamic 18 mobility management approaches, with the objective of reducing 19 operators' burdens, evolving to a cheaper and more efficient 20 architecture. 22 This draft describes multiple solutions for network-based distributed 23 mobility management inspired by the well known Proxy Mobile IPv6. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 29 document are to be interpreted as described in RFC 2119 [RFC2119]. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on September 6, 2015. 48 Copyright Notice 50 Copyright (c) 2015 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (http://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 3. Partially distributed solution . . . . . . . . . . . . . . . 4 68 3.1. Initial registration . . . . . . . . . . . . . . . . . . 6 69 3.2. The CMD as PBU/PBA relay . . . . . . . . . . . . . . . . 7 70 3.3. The CMD as MAAR locator . . . . . . . . . . . . . . . . . 9 71 3.4. The CMD as MAAR proxy . . . . . . . . . . . . . . . . . . 10 72 3.5. De-registration . . . . . . . . . . . . . . . . . . . . . 11 73 3.6. Message Format . . . . . . . . . . . . . . . . . . . . . 11 74 3.6.1. Previous MAAR Option . . . . . . . . . . . . . . . . 11 75 3.6.2. Serving MAAR Option . . . . . . . . . . . . . . . . . 13 76 4. Fully distributed solution . . . . . . . . . . . . . . . . . 13 77 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 78 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 79 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 80 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 81 8.1. Normative References . . . . . . . . . . . . . . . . . . 15 82 8.2. Informative References . . . . . . . . . . . . . . . . . 15 83 Appendix A. Comparison with Requirement document . . . . . . . . 15 84 A.1. Distributed mobility management . . . . . . . . . . . . . 15 85 A.2. Bypassable network-layer mobility support for each 86 application session . . . . . . . . . . . . . . 16 87 A.3. IPv6 deployment . . . . . . . . . . . . . . . . . . . . . 16 88 A.4. Existing mobility protocols . . . . . . . . . . . . . . . 16 89 A.5. Coexistence with deployed networks/hosts and operability 90 across different networks . . . . . . . . . . . . . . . . 17 91 A.6. Operation and management considerations . . . . . . . . . 17 92 A.7. Security considerations . . . . . . . . . . . . . . . . . 17 93 A.8. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 18 94 Appendix B. Implementation experience . . . . . . . . . . . . . 18 95 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 97 1. Introduction 99 Current IP mobility solutions, standardized with the names of Mobile 100 IPv6 [RFC6275], or Proxy Mobile IPv6 [RFC5213], just to cite the two 101 most relevant examples, offer mobility support at the cost of 102 handling operations at a cardinal point, the mobility anchor, and 103 burdening it with data forwarding and control mechanisms for a great 104 amount of users. As stated in [RFC7333], centralized mobility 105 solutions are prone to several problems and limitations: longer (sub- 106 optimal) routing paths, scalability problems, signaling overhead (and 107 most likely a longer associated handover latency), more complex 108 network deployment, higher vulnerability due to the existence of a 109 potential single point of failure, and lack of granularity on the 110 mobility management service (i.e., mobility is offered on a per-node 111 basis, not being possible to define finer granularity policies, as 112 for example per-application). 114 The purpose of Distributed Mobility Management is to overcome the 115 limitations of the traditional centralized mobility management 116 [RFC7333] [RFC7429]; the main concept behind DMM solutions is indeed 117 bringing the mobility anchor closer to the MN. Following this idea, 118 in our proposal, the central anchor is moved to the edge of the 119 network, being deployed in the default gateway of the mobile node. 120 That is, the first elements that provide IP connectivity to a set of 121 MNs are also the mobility managers for those MNs. In the following, 122 we will call these entities Mobility Anchor and Access Routers 123 (MAARs). 125 This document focuses on network-based DMM, hence the starting point 126 is making PMIPv6 working in a distributed manner [RFC7429]. In our 127 proposal, as in PMIPv6, mobility is handled by the network without 128 the MNs involvement, but, differently from PMIP, when the MN moves 129 from one access network to another, it also changes anchor router, 130 hence requiring signaling between the anchors to retrieve the MN's 131 previous location(s). Also, a key-aspect of network-based DMM, is 132 that a prefix pool belongs exclusively to each MAAR, in the sense 133 that those prefixes are assigned by the MAAR to the MNs attached to 134 it, and they are routable at that MAAR. 136 In the following, we consider two main approaches to design our DMM 137 solutions: 139 o Partially distributed schemes, where the data plane only is 140 distributed among access routers similar to MAGs, whereas the 141 control plane is kept centralized towards a cardinal node used as 142 information store, but relieved from any route management and MN's 143 data forwarding task. 145 o Fully distributed schemes, where both data and control planes are 146 distributed among the access routers. 148 2. Terminology 150 The following terms used in this document are defined in the Proxy 151 Mobile IPv6 specification [RFC5213]: 153 Local Mobility Anchor (LMA) 155 Mobile Access Gateway (MAG) 157 Mobile Node (MN) 159 Binding Cache Entry (BCE) 161 Proxy Care-of Address (P-CoA) 163 Proxy Binding Update (PBU) 165 Proxy Binding Acknowledgement (PBA) 167 The following terms are defined and used in this document: 169 MAAR (Mobility Anchor and Access Router). First hop router where the 170 mobile nodes attach to. It also plays the role of mobility 171 manager for the IPv6 prefixes it anchors, running the 172 functionalities of PMIP's MAG and LMA. 174 CMD (Central Mobility Database). Node that stores the BCEs allocated 175 for the MNs in the mobility domain. 177 P-MAAR (Previous MAAR). MAAR which was previously visited by the MN 178 and is still involved in an active flow using an IPv6 prefix it 179 has advertised to the MN (i.e., MAAR where that IPv6 prefix is 180 anchored). There might be multiple P-MAARs for an MN's mobility 181 session. 183 S-MAAR (Serving MAAR). MAAR which the MN is currently attached to. 185 3. Partially distributed solution 187 The following solution consists in de-coupling the entities that 188 participates in the data and the control planes: the data plane 189 becomes distributed and managed by the MAARs near the edge of the 190 network, while the control plane, besides on the MAARs, relies on a 191 central entity called Central Mobility Database (CMD). In the 192 proposed architecture, the hierarchy present in PMIP between LMA and 193 MAG is preserved, but with the following substantial variations: 195 o The LMA is relieved from the data forwarding role, only the 196 Binding Cache and its management operations are maintained. Hence 197 the LMA is renamed into Central Mobility Database (CMD). Also, 198 the CMD is able to send and parse both PBU and PBA messages. 200 o The MAG is enriched with the LMA functionalities, hence the name 201 Mobility Anchor and Access Router (MAAR). It maintains a local 202 Binding Cache for the MNs that are attached to it and it is able 203 to send and parse PBU and PBA messages. 205 o The binding cache will have to be extended to include information 206 regarding previous MAARs where the mobile node was anchored and 207 still retains active data sessions, see Appendix B for further 208 details. 210 o Each MAAR has a unique set of global prefixes (which are 211 configurable), that can be allocated by the MAAR to the MNs, but 212 must be exclusive to that MAAR, i.e. no other MAAR can allocate 213 the same prefixes. 215 The MAARs leverage on the Central Mobility Database (CMD) to access 216 and update information related to the MNs, stored as mobility 217 sessions; hence, a centralized node maintains a global view on the 218 status of the network. The CMD is queried whenever a MN is detected 219 to join/leave the mobility domain. It might be a fresh attachment, a 220 detachment or a handover, but as MAARs are not aware of past 221 information related to a mobility session, they contact the CMD to 222 retrieve the data of interest and eventually take the appropriate 223 action. The procedure adopted for the query and the messages 224 exchange sequence might vary to optimize the update latency and/or 225 the signaling overhead. Here is presented one method for the initial 226 registration, and three different approaches to update the mobility 227 sessions using PBUs and PBAs. Each approach assigns a different role 228 to the CMD: 230 o The CMD is a PBU/PBA relay; 232 o The CMD is only a MAAR locator; 234 o The CMD is a PBU/PBA proxy. 236 3.1. Initial registration 238 Upon the MN's attachment to a MAAR, say MAAR1, if the MN is 239 authorized for the service, an IPv6 global prefix belonging to the 240 MAAR's prefix pool is reserved for it (Pref1) into a temporal Binding 241 Cache Entry (BCE) allocated locally. The prefix is sent in a 242 [RFC5213] PBU with the MN's Identifier (MN-ID) to the CMD, which, 243 since the session is new, stores a permanent BCE containing as main 244 fields the MN-ID, the MN's prefix and MAAR1's address as Proxy-CoA. 245 The CMD replies to MAAR1 with a PBA including the usual options 246 defined in PMIP/RFC5213, meaning that the MN's registration is fresh 247 and no past status is available. MAAR1 definitely stores the 248 temporal BCE previously allocated and unicasts a Router Advertisement 249 (RA) to the MN including the prefix reserved before, that can be used 250 by the MN to configure an IPv6 address (e.g., with stateless auto- 251 configuration). The address is routable at the MAAR, in the sense 252 that it is on the path of packets addressed to the MN. Moreover, the 253 MAAR acts as plain router for those packets, as no encapsulation nor 254 special handling takes place. Figure 1 illustrates this scenario. 256 +-----+ +---+ +--+ 257 |MAAR1| |CMD| |CN| 258 +-----+ +---+ +*-+ 259 | | * 260 MN | * +---+ 261 attach. | ***** _|CMD|_ 262 detection | flow1 * / +-+-+ \ 263 | | * / | \ 264 local BCE | * / | \ 265 allocation | * / | \ 266 |--- PBU -->| +---*-+-' +--+--+ `+-----+ 267 | BCE | * | | | | | 268 | creation |MAAR1+------+MAAR2+-----+MAAR3| 269 |<-- PBA ---| | * | | | | | 270 local BCE | +---*-+ +-----+ +-----+ 271 finalized | * 272 | | Pref1 * 273 | | +*-+ 274 | | |MN| 275 | | +--+ 277 Operations sequence Packets flow 279 Figure 1: First attachment to the network 281 3.2. The CMD as PBU/PBA relay 283 When the MN moves from its current access and associates to MAAR2 284 (now the S-MAAR), MAAR2 reserves another IPv6 prefix (Pref2), it 285 stores a temporal BCE, and it sends a plain PBU to the CMD for 286 registration. Upon PBU reception and BC lookup, the CMD retrieves an 287 already existing entry for the MN, binding the MN-ID to its former 288 location; thus, the CMD forwards the PBU to the MAAR indicated as 289 Proxy CoA (MAAR1), including a new mobility option to communicate the 290 S-MAAR's global address to MAAR1, defined as Serving MAAR Option in 291 Section 3.6.2. The CMD updates the P-CoA field in the BCE related to 292 the MN with the S-MAAR's address. 294 Upon PBU reception, MAAR1 can install a tunnel on its side towards 295 MAAR2 and the related routes for Pref1. Then MAAR1 replies to the 296 CMD with a PBA (including the option mentioned before) to ensure that 297 the new location has successfully changed, containing the prefix 298 anchored at MAAR1 in the Home Network Prefix option. The CMD, after 299 receiving the PBA, updates the BCE populating an instance of the 300 P-MAAR list. The P-MAAR list is an additional field on the BCE that 301 contains an element for each P-MAAR involved in the MN's mobility 302 session. The list element contains the P-MAAR's global address and 303 the prefix it has delegated (see Appendix B for further details). 304 Also, the CMD send a PBA to the new S-MAAR, containing the previous 305 Proxy-CoA and the prefix anchored to it embedded into a new mobility 306 option called Previous MAAR Option (defined in Section 3.6.1), so 307 that, upon PBA arrival, a bi-directional tunnel can be established 308 between the two MAARs and new routes are set appropriately to recover 309 the IP flow(s) carrying Pref1. 311 Now packets destined to Pref1 are first received by MAAR1, 312 encapsulated into the tunnel and forwarded to MAAR2, which finally 313 delivers them to their destination. In uplink, when the MN transmits 314 packets using Pref1 as source address, they are sent to MAAR2, as it 315 is MN's new default gateway, then tunneled to MAAR1 which routes them 316 towards the next hop to destination. Conversely, packets carrying 317 Pref2 are routed by MAAR2 without any special packet handling both 318 for uplink and downlink. The procedure is depicted in Figure 2. 320 +-----+ +---+ +-----+ +--+ +--+ 321 |MAAR1| |CMD| |MAAR2| |CN| |CN| 322 +-----+ +---+ +-----+ +*-+ +*-+ 323 | | | * * 324 | | MN * +---+ * 325 | | attach. ***** _|CMD|_ * 326 | | det. flow1 * / +-+-+ \ *flow2 327 | |<-- PBU ---| * / | \ * 328 | BCE | * / | ******* 329 | check+ | * / | * \ 330 | update | +---*-+-? +--+-*+ `+-----+ 331 |<-- PBU*---| | | * | | *| | | 332 route | | |MAAR1|______|MAAR2+-----+MAAR3| 333 update | | | **(______)** *| | | 334 |--- PBA*-->| | +-----+ +-*--*+ +-----+ 335 | BCE | * * 336 | update | Pref1 * *Pref2 337 | |--- PBA*-->| +*--*+ 338 | | route ---move-->|*MN*| 339 | | update +----+ 341 Operations sequence Data Packets flow 342 PBU/PBA Messages with * contain 343 a new mobility option 345 Figure 2: Scenario after a handover, CMD as relay 347 For next MN's movements the process is repeated except for the number 348 of P-MAARs involved, that rises accordingly to the number of prefixes 349 that the MN wishes to maintain. Indeed, once the CMD receives the 350 first PBU from the new S-MAAR, it forwards copies of the PBU to all 351 the P-MAARs indicated in the BCE as current P-CoA (i.e., the MAAR 352 prior to handover) and in the P-MAARs list. They reply with a PBA to 353 the CMD, which aggregates them into a single one to notify the 354 S-MAAR, that finally can establish the tunnels with the P-MAARs. 356 It should be noted that this design separates the mobility management 357 at the prefix granularity, and it can be tuned in order to erase old 358 mobility sessions when not required, while the MN is reachable 359 through the latest prefix acquired. Moreover, the latency associated 360 to the mobility update is bound to the PBA sent by the furthest 361 P-MAAR, in terms of RTT, that takes the longest time to reach the 362 CMD. The drawback can be mitigated introducing a timeout at the CMD, 363 by which, after its expiration, all the PBAs so far collected are 364 transmitted, and the remaining are sent later upon their arrival. 366 3.3. The CMD as MAAR locator 368 The handover latency experienced in the approach shown before can be 369 reduced if the P-MAARs are allowed to signal directly their 370 information to the new S-MAAR. This procedure reflect what was 371 described in Section 3.2 up to the moment the P-MAAR receives the PBU 372 with the P-MAAR option. At that point a P-MAAR is aware of the new 373 MN's location (because of the S-MAAR's address in the S-MAAR option), 374 and, besides sending a PBA to the CMD, it also sends a PBA to the 375 S-MAAR including the prefix it is anchoring. This latter PBA does 376 not need to include new options, as the prefix is embedded in the HNP 377 option and the P-MAAR's address OS taken from the message's source 378 address. The CMD is relieved from forwarding the PBA to the S-MAAR, 379 as the latter receives a copy directly from the P-MAAR with the 380 necessary information to build the tunnels and set the appropriate 381 routes. In Figure 3 is illustrated the new messages sequence, while 382 the data forwarding is unaltered. 384 +-----+ +---+ +-----+ +--+ +--+ 385 |MAAR1| |CMD| |MAAR2| |CN| |CN| 386 +-----+ +---+ +-----+ +*-+ +*-+ 387 | | | * * 388 | | MN * +---+ * 389 | | attach. ***** _|CMD|_ * 390 | | det. flow1 * / +-+-+ \ *flow2 391 | |<-- PBU ---| * / | \ * 392 | BCE | * / | ******* 393 | check+ | * / | * \ 394 | update | +---*-+-? +--+-*+ `+-----+ 395 |<-- PBU*---| | | * | | *| | | 396 route | | |MAAR1|______|MAAR2+-----+MAAR3| 397 update | | | **(______)** *| | | 398 |--------- PBA -------->| +-----+ +-*--*+ +-----+ 399 |--- PBA*-->| route * * 400 | BCE update Pref1 * *Pref2 401 | update | +*--*+ 402 | | | ---move-->|*MN*| 403 | | | +----+ 405 Operations sequence Data Packets flow 406 PBU/PBA Messages with * contain 407 a new mobility option 409 Figure 3: Scenario after a handover, CMD as locator 411 3.4. The CMD as MAAR proxy 413 A further enhancement of previous solutions can be achieved when the 414 CMD sends the PBA to the new S-MAAR before notifying the P-MAARs of 415 the location change. Indeed, when the CMD receives the PBU for the 416 new registration, it is already in possess of all the information 417 that the new S-MAAR requires to set up the tunnels and the routes. 418 Thus the PBA is sent to the S-MAAR immediately after a PBU is 419 received, including also in this case the P-MAAR option. In 420 parallel, a PBU is sent by the CMD to the P-MAARs containing the 421 S-MAAR option, to notify them about the new MN's location, so they 422 receive the information to establish the tunnels and routes on their 423 side. When P-MAARs complete the update, they send a PBA to the CMD 424 to indicate that the operation is concluded and the information are 425 updated in all network nodes. This procedure is obtained from the 426 first one re-arranging the order of the messages, but the parameters 427 communicated are the same. This scheme is depicted in Figure 4, 428 where, again, the data forwarding is kept untouched. 430 +-----+ +---+ +-----+ +--+ +--+ 431 |MAAR1| |CMD| |MAAR2| |CN| |CN| 432 +-----+ +---+ +-----+ +*-+ +*-+ 433 | | | * * 434 | | MN * +---+ * 435 | | attach. ***** _|CMD|_ * 436 | | det. flow1 * / +-+-+ \ *flow2 437 | |<-- PBU ---| * / | \ * 438 | BCE | * / | ******* 439 | check+ | * / | * \ 440 | update | +---*-+-? +--+-*+ `+-----+ 441 |<-- PBU*---x--- PBA*-->| | * | | *| | | 442 route | route |MAAR1|______|MAAR2+-----+MAAR3| 443 update | update | **(______)** *| | | 444 |--- PBA*-->| | +-----+ +-*--*+ +-----+ 445 | BCE | * * 446 | update | Pref1 * *Pref2 447 | | | +*--*+ 448 | | | ---move-->|*MN*| 449 | | | +----+ 451 Operations sequence Data Packets flow 452 PBU/PBA Messages with * contain 453 a new mobility option 455 Figure 4: Scenario after a handover, CMD as proxy 457 3.5. De-registration 459 The de-registration mechanism devised for PMIPv6 is no longer valid 460 in the Partial DMM architecture. This is motivated by the fact that 461 each MAAR handles an independent mobility session (i.e., a single or 462 a set of prefixes) for a given MN, whereas the aggregated session is 463 stored at the CMD. Indeed, when a previous MAAR initiates a de- 464 registration procedure, because the MN is no longer present on the 465 MAAR's access link, it removes the routing state for that (those) 466 prefix(es), that would be deleted by the CMD as well, hence defeating 467 any prefix continuity attempt. The simplest approach to overcome 468 this limitation is to deny an old MAAR to de-register a prefix, that 469 is, allowing only a serving MAAR to de-register the whole MN session. 470 This can be achieved by first removing any layer-2 detachment event, 471 so that de-registration is triggered only when the session lifetime 472 expires, hence providing a guard interval for the MN to connect to a 473 new MAAR. Then, a change in the MAAR operations is required, and at 474 this stage two possible solutions can be deployed: 476 o A previous MAAR stops the BCE timer upon receiving a PBU from the 477 CMD containing a "Serving MAAR" option. In this way only the 478 Serving MAAR is allowed to de-register the mobility session, 479 arguing that the MN left definitely the domain. 481 o Previous MAARs can, upon BCE expiry, send de-registration messages 482 to the CMD, which, instead of acknowledging the message with a 0 483 lifetime, send back a PBA with a non-zero lifetime, hence re- 484 newing the session, if the MN is still connected to the domain. 486 The evaluation of these methods is left for future work. 488 3.6. Message Format 490 This section defines two Mobility Options to be used in the PBU and 491 PBA messages: 493 Previous MAAR Option; 495 Serving MAAR Option. 497 In the current draft the messages reflect IPv6 format only. IPv4 498 compatibility will be added in next release. 500 3.6.1. Previous MAAR Option 502 This new option is defined for use with the Proxy Binding 503 Acknowledgement messages exchanged by the CMD to a MAAR. This option 504 is used to notify the S-MAAR about the previous MAAR's global address 505 and the prefix anchored to it. There can be multiple Previous MAAR 506 options present in the message. Its format is as follows: 508 0 1 2 3 509 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 510 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 511 | Type | Length | Prefix Length | 512 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 513 | | 514 + + 515 | | 516 + P-MAAR's address + 517 | | 518 + + 519 | | 520 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 521 | | 522 + + 523 | | 524 + Home Network Prefix + 525 | | 526 + + 527 | | 528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 530 Type 532 To be assigned by IANA. 534 Length 536 8-bit unsigned integer indicating the length of the option in 537 octets, excluding the type and length fields. This field MUST be 538 set to 34. 540 Prefix Length 542 8-bit unsigned integer indicating the prefix length of the IPv6 543 prefix contained in the option. 545 Previous MAAR's address 547 A sixteen-byte field containing the P-MAAR's IPv6 global address. 549 Home Network Prefix 551 A sixteen-byte field containing the mobile node's IPv6 Home 552 Network Prefix. 554 3.6.2. Serving MAAR Option 556 This new option is defined for use with the Proxy Binding Update and 557 Proxy Binding Acknowledgement messages exchanged between the CMD and 558 a Previous MAAR. This option is used to notify the P-MAAR about the 559 current Serving MAAR's global address. Its format is as follows: 561 0 1 2 3 562 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 563 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 564 | Type | Length | 565 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 566 | | 567 + + 568 | | 569 + S-MAAR's address + 570 | | 571 + + 572 | | 573 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 575 Type 577 To be assigned by IANA. 579 Length 581 8-bit unsigned integer indicating the length of the option in 582 octets, excluding the type and length fields. This field MUST be 583 set to 16. 585 Serving MAAR's address 587 A sixteen-byte field containing the S-MAAR's IPv6 global address. 589 4. Fully distributed solution 591 In this section we introduce the guidelines to evolve our partially 592 DMM solution into a fully distributed one. We list the key concepts 593 in the following (some of the points are already enforced in previous 594 sections of this document): 596 o All MAARs have a pool of global routable IPv6 prefixes to be 597 assigned to MNs on the access link. 599 o Any central control entity is removed from the architecture and 600 each MAAR will retain it's own cache for the mobile nodes directly 601 anchored to it. 603 o Both control and data planes are now entirely handled by the 604 MAARs. 606 Because we aim for a fully distributed approach, the lack of 607 knowledge of other MAARs and their advertised prefixes becomes a 608 serious obstacle. In this particular case, when a MN attaches to a 609 MAAR, there are two main pieces ofi nformation that this MAAR 610 requires to know, to properly assure a mobile node's mobility and 611 continuity of its data flows: i) if the node has any P-MAARs and 612 their addresses; ii) if it has P-MAARs, which prefixes were 613 advertised by which MAAR. 615 There are several methods to achieve this: 617 o Make before approaches, employing Layer 2 or Layer 3 mechanisms. 618 The target MAAR is known in advance by the current MAAR before 619 handover, hence the mobility context can be transferred. 621 o Distributed schemes for MAAR discovery: it can based on a peer-to- 622 peer approach; or it can employ a unicast, multicast or broadcast 623 query system. 625 o Explicit notification by the MN. For example, extending the layer 626 three IP address configuration mechanisms (e.g., ND). 628 o Other MN to MAAR communication protocol (e.g., IEEE 802.21). 630 5. IANA Considerations 632 TBD. 634 6. Security Considerations 636 The solution assumes that the nodes are trusted and secure MAAR-to- 637 MAAR communications are in place, for instance re-using the security 638 mechanisms defined for PMIPv6. Thus, the solution does not introduce 639 any new security vulnerability. 641 7. Acknowledgments 643 The authors would like to thank Marco Liebsch for his comments and 644 discussion on this document. 646 8. References 648 8.1. Normative References 650 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 651 Requirement Levels", BCP 14, RFC 2119, March 1997. 653 [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., 654 and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 656 [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support 657 in IPv6", RFC 6275, July 2011. 659 8.2. Informative References 661 [I-D.bernardos-dmm-distributed-anchoring] 662 Bernardos, C. and J. Zuniga, "PMIPv6-based distributed 663 anchoring", draft-bernardos-dmm-distributed-anchoring-04 664 (work in progress), May 2014. 666 [RFC7333] Chan, H., Liu, D., Seite, P., Yokota, H., and J. Korhonen, 667 "Requirements for Distributed Mobility Management", RFC 668 7333, August 2014. 670 [RFC7429] Liu, D., Zuniga, JC., Seite, P., Chan, H., and CJ. 671 Bernardos, "Distributed Mobility Management: Current 672 Practices and Gap Analysis", RFC 7429, January 2015. 674 Appendix A. Comparison with Requirement document 676 In this section we descrbe how our solution addresses the DMM 677 requirements listed in [RFC7333]. 679 A.1. Distributed mobility management 681 "IP mobility, network access solutions, and forwarding solutions 682 provided by DMM MUST enable traffic to avoid traversing a single 683 mobility anchor far from the optimal route." 685 In our solution, a MAAR is responsible to handle the mobility for 686 those IP flows started when the MN is attached to it. As long as the 687 MN remains connected to the MAAR's access links, the IP packets of 688 such flows can benefit from the optimal path. When the MN moves to 689 another MAAR, the path becomes non-optimal for ongoing flows, as they 690 are anchored to the previous MAAR, but newly started IP sessions are 691 forwarded by the new MAAR through the optimal path. 693 A.2. Bypassable network-layer mobility support for each application 694 session 696 "DMM solutions MUST enable network-layer mobility, but it MUST be 697 possible for any individual active application session (flow) to not 698 use it. Mobility support is needed, for example, when a mobile host 699 moves and an application cannot cope with a change in the IP address. 700 Mobility support is also needed when a mobile router changes its IP 701 address as it moves together with a host and, in the presence of 702 ingress filtering, an application in the host is interrupted. 703 However, mobility support at the network layer is not always needed; 704 a mobile node can often be stationary, and mobility support can also 705 be provided at other layers. It is then not always necessary to 706 maintain a stable IP address or prefix for an active application 707 session." 709 Our DMM solution operates at the IP layer, hence upper layers are 710 totally transparent to the mobility operations. In particular, 711 ongoing IP sessions are not disrupted after a change of access 712 network. The routability of the old address is ensured by the IP 713 tunnel with the old MAAR. New IP sessions are started with the new 714 address. From the application's perspective, those processes which 715 sockets are bound to a unique IP address do not suffer any impact. 716 For the other applications, the sockets bound to the old address are 717 preserved, whereas next sockets use the new address. 719 A.3. IPv6 deployment 721 "DMM solutions SHOULD target IPv6 as the primary deployment 722 environment and SHOULD NOT be tailored specifically to support IPv4, 723 particularly in situations where private IPv4 addresses and/or NATs 724 are used." 726 The DMM solution we propose targets IPv6 only. 728 A.4. Existing mobility protocols 730 "A DMM solution MUST first consider reusing and extending IETF 731 standard protocols before specifying new protocols." 733 This DMM solution is derived from the operations and messages 734 specified in [RFC5213]. 736 A.5. Coexistence with deployed networks/hosts and operability across 737 different networks 739 "A DMM solution may require loose, tight, or no integration into 740 existing mobility protocols and host IP stacks. Regardless of the 741 integration level, DMM implementations MUST be able to coexist with 742 existing network deployments, end hosts, and routers that may or may 743 not implement existing mobility protocols. Furthermore, a DMM 744 solution SHOULD work across different networks, possibly operated as 745 separate administrative domains, when the needed mobility management 746 signaling, forwarding, and network access are allowed by the trust 747 relationship between them" 749 The partially DMM solution can be extended to provide a fallback 750 mechanism to operate as legacy Proxy Mobile IPv6. It is necessary to 751 instruct MAARs to always establish a tunnel with the same MAAR, 752 working as LMA. The fully DMM solution can be extended as well, but 753 it requires more intervention. The partially DMM solution can be 754 deployed across different domains with trust agreements if the CMDs 755 ot the operators are enabled to transfer context from one node to 756 another. The fully DMM solution works across multiple domains if 757 both solution apply the same signalling scheme. 759 A.6. Operation and management considerations 761 "A DMM solution needs to consider configuring a device, monitoring 762 the current operational state of a device, and responding to events 763 that impact the device, possibly by modifying the configuration and 764 storing the data in a format that can be analyzed later. 766 The proposed solution can re-use existing mechanisms defined for the 767 operation and management of Proxy Mobile IPv6. 769 A.7. Security considerations 771 "A DMM solution MUST support any security protocols and mechanisms 772 needed to secure the network and to make continuous security 773 improvements. In addition, with security taken into consideration 774 early in the design, a DMM solution MUST NOT introduce new security 775 risks or amplify existing security risks that cannot be mitigated by 776 existing security protocols and mechanisms." 778 The proposed solution does not specify a security mechanism, given 779 that the same mechanism for PMIPv6 can be used. 781 A.8. Multicast 783 "DMM SHOULD enable multicast solutions to be developed to avoid 784 network inefficiency in multicast traffic delivery." 786 This solution in its current version does not specify any support for 787 multicast traffic, which is left for study in future versions. 789 Appendix B. Implementation experience 791 The network-based DMM solution described in section Section 3.4 is 792 now available at the Open Distributed Mobility Management (ODMM) 793 project (http://www.odmm.net), under the name of Mobility Anchors 794 Distribution for PMIPv6 (MAD-PMIPv6). The ODMM platform is intended 795 to foster DMM development and deployment, by serving as a framework 796 to host open source implementations. 798 The MAD-PMIPv6 code is developed in ANSI C from the existing UMIP 799 implementation for PMIP. The most relevant changes with respect to 800 the UMIP original version are related to how to create the CMD and 801 MAAR's state machines from those of an LMA and a MAG; for this 802 purpose, part of the LMA code was copied to the MAG, in order to send 803 PBA messages and parse PBU. Also, the LMA routing functions were 804 removed completely, and moved to the MAG, because MAARs need to route 805 through the tunnels in downlink (as an LMA) and in uplink (as a MAG). 807 Tunnel management is hence a relevant technical aspect, as multiple 808 tunnels are established by a single MAAR, which keeps their status 809 directly into the MN's BCE. Indeed, from the implementation 810 experience it was chosen to create an ancillary data structure as 811 field within a BCE: the data structure is called "MAAR list" and 812 stores the previous MAARs' address and the corresponding prefix(es) 813 assigned for the MN. Only the CMD and the serving MAAR store this 814 data structure, because the CMD maintains the global MN's mobility 815 session formed during the MN's roaming within the domain, and the 816 serving MAAR needs to know which previous MAARs were visited, the 817 prefix(es) they assigned and the tunnels established with them. 818 Conversely, a previous MAAR only needs to know which is the current 819 Serving MAAR and establish a single tunnel with it. For this reason, 820 a MAAR that receives a PBU from the CMD (meaning that the MN attached 821 to another MAAR), first sets up the routing state for the MN's 822 prefix(es) it is anchoring, then stop the BCE expiry timer and 823 deletes the MAAR list (if present) since it is no longer useful. 825 In order to have the MN totally unaware of the changes in the access 826 link, all MAARs implement the Distributed Logical Interface (DLIF) 827 concept devised in [I-D.bernardos-dmm-distributed-anchoring]. 828 Moreover, it should be noted that the protocols designed in the 829 document work only at the network layer to handle the MNs joining or 830 leaving the domain. This should guarantee a certain independency to 831 a particular access technology. The implementation reflects this 832 reasoning, but we argue that an interaction with lower layers 833 produces a more effective attachment and detachment detection, 834 therefore improving the performance, also regarding de-registration 835 mechanisms. 837 It was chosen to implement the "proxy" solution because it produces 838 the shortest handover latency, but a slight modification on the CMD 839 state machine can produce the first scenario described ("relay") 840 which guarantees a more consistent request/ack scheme between the 841 MAARS. By modifying also the MAAR's state machine it can be 842 implemented the second solution ("locator"). 844 An early MAD-PMIPv6 implementation was shown during a demo session at 845 the IETF 83rd, in Paris in March 2012. An enhancement version of the 846 prototype has been presented at the 87th IETF meeting in Berlin, July 847 2013. The updated demo included a use case scenario employing a CDN 848 system for video delivery. More, MAD-PMIPv6 has been extensively 849 used and evaluated within a testbed employing heterogeneous radio 850 accesses within the framework of the MEDIEVAL EU project. MAD-PMIPv6 851 software is currently part of a DMM test-bed comprising 3 MAARs, one 852 CMD, one MN and a CN. All the machines used in the demos were Linux 853 UBUNTU 10.04 systems with kernel 2.6.32, but the prototype has been 854 tested also under newer systems. This testbed is being maintained by 855 the iJOIN EU project. 857 Authors' Addresses 859 Carlos J. Bernardos 860 Universidad Carlos III de Madrid 861 Av. Universidad, 30 862 Leganes, Madrid 28911 863 Spain 865 Phone: +34 91624 6236 866 Email: cjbc@it.uc3m.es 867 URI: http://www.it.uc3m.es/cjbc/ 868 Antonio de la Oliva 869 Universidad Carlos III de Madrid 870 Av. Universidad, 30 871 Leganes, Madrid 28911 872 Spain 874 Phone: +34 91624 8803 875 Email: aoliva@it.uc3m.es 876 URI: http://www.it.uc3m.es/aoliva/ 878 Fabio Giust 879 Universidad Carlos III de Madrid 880 Av. Universidad, 30 881 Leganes, Madrid 28911 882 Spain 884 Phone: +34 91624 8859 885 Email: fgiust@it.uc3m.es 886 URI: http://www.it.uc3m.es/fgiust/