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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-18) exists of draft-ietf-netlmm-pmip6-ipv4-support-08 ** Obsolete normative reference: RFC 4306 (Obsoleted by RFC 5996) ** Obsolete normative reference: RFC 3775 (Obsoleted by RFC 6275) Summary: 3 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NETLMM Working Group V. Devarapalli (ed.) 3 Internet-Draft WiChorus 4 Intended status: Standards Track R. Koodli (ed.) 5 Expires: September 24, 2009 Starent Networks 6 H. Lim 7 N. Kant 8 Stoke 9 S. Krishnan 10 Ericsson 11 J. Laganier 12 DOCOMO Euro-Labs 13 March 23, 2009 15 Heartbeat Mechanism for Proxy Mobile IPv6 16 draft-ietf-netlmm-pmipv6-heartbeat-06.txt 18 Status of this Memo 20 This Internet-Draft is submitted to IETF in full conformance with the 21 provisions of BCP 78 and BCP 79. This document may not be modified, 22 and derivative works of it may not be created, except to format it 23 for publication as an RFC or to translate it into languages other 24 than English. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF), its areas, and its working groups. Note that 28 other groups may also distribute working documents as Internet- 29 Drafts. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 The list of current Internet-Drafts can be accessed at 37 http://www.ietf.org/ietf/1id-abstracts.txt. 39 The list of Internet-Draft Shadow Directories can be accessed at 40 http://www.ietf.org/shadow.html. 42 This Internet-Draft will expire on September 24, 2009. 44 Copyright Notice 46 Copyright (c) 2009 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents in effect on the date of 51 publication of this document (http://trustee.ietf.org/license-info). 52 Please review these documents carefully, as they describe your rights 53 and restrictions with respect to this document. 55 Abstract 57 Proxy Mobile IPv6 is a network-based mobility management protocol. 58 The mobility entities involved in the Proxy Mobile IPv6 protocol, the 59 Mobile Access Gateway (MAG) and the Local Mobility Anchor (LMA), 60 setup tunnels dynamically to manage mobility for a mobile node within 61 the Proxy Mobile IPv6 domain. This document describes a heartbeat 62 mechanism between the MAG and the LMA to detect failures quickly and 63 take appropriate action. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 68 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 69 3. Heartbeat Mechanism . . . . . . . . . . . . . . . . . . . . . 3 70 3.1. Failure Detection . . . . . . . . . . . . . . . . . . . . 4 71 3.2. Restart Detection . . . . . . . . . . . . . . . . . . . . 5 72 3.3. Heartbeat Message . . . . . . . . . . . . . . . . . . . . 6 73 3.4. Restart Counter Mobility Option . . . . . . . . . . . . . 7 74 4. Exchanging Heartbeat Messages over an IPv4 Transport 75 Network . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 76 5. Configuration Variables . . . . . . . . . . . . . . . . . . . 8 77 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 78 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 79 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 80 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 81 9.1. Normative References . . . . . . . . . . . . . . . . . . . 10 82 9.2. Informative References . . . . . . . . . . . . . . . . . . 10 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 85 1. Introduction 87 Proxy Mobile IPv6 [RFC5213] enables network-based mobility for IPv6 88 hosts that do not implement any mobility protocols. The protocol is 89 described in detail in [RFC5213]. In order to facilitate the 90 network-based mobility, the PMIPv6 protocol defines a Mobile Access 91 Gateway (MAG), which acts as a proxy for the Mobile IPv6 [RFC3775] 92 signaling, and the Local Mobility Anchor (LMA) which acts similar to 93 a Home Agent, anchoring a Mobile Node's sessions within a Proxy 94 Mobile IPv6 (PMIPv6) domain. The LMA and the MAG establish a 95 bidirectional tunnel for forwarding all data traffic belonging to the 96 Mobile Nodes. 98 In a distributed environment such as a PMIPv6 domain consisting of 99 LMA and MAGs, it is necessary for the nodes to 1) have a consistent 100 state about each other's reachability, and 2) quickly inform peers in 101 the event of recovery from node failures. So, when the LMA restarts 102 after a failure, the MAG should (quickly) learn about the restart so 103 that it could take appropriate actions (such as releasing any 104 resources). When there are no failures, a MAG should know about 105 LMA's reachability (and vice versa) so that the path can be assumed 106 to be functioning. 108 This document specifies a heartbeat mechanism between the MAG and the 109 LMA to detect the status of reachability between them. This document 110 also specifies a mechanism to indicate node restarts; the mechanism 111 could be used to quickly inform peers of such restarts. The 112 heartbeat message is a mobility header message (protocol type 135) 113 which is periodically exchanged at a configurable threshold of time 114 or sent unsolicited soon after a node restart. This document does 115 not specify the specific actions (such as releasing resources) that a 116 node takes as a response to processing the heartbeat messages. 118 2. Terminology 120 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 121 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 122 document are to be interpreted as described in [RFC2119]. 124 3. Heartbeat Mechanism 126 The MAG and the LMA exchange heartbeat messages every 127 HEARTBEAT_INTERVAL seconds to detect the current status of 128 reachability between them. The MAG initiates the heartbeat exchange 129 to test if the LMA is reachable by sending a Heartbeat Request 130 message to the LMA. Each Heartbeat Request contains a sequence 131 number that is incremented monotonically. The sequence number on the 132 last Heartbeat Request message is always recorded by the MAG, and is 133 used to match the corresponding Heartbeat Response. Similarly, the 134 LMA also initiates a heartbeat exchange with the MAG, by sending a 135 Heartbeat Request message, to check if the MAG is reachable. The 136 format of the Heartbeat message is described in Section 3.3. 138 A Heartbeat Request message can be sent only if the MAG has at least 139 one proxy binding cache entry at the LMA for a mobile node attached 140 to the MAG. If there are no proxy binding cache entries at the LMA 141 for any of the mobile nodes attached to the MAG, then the heartbeat 142 message SHOULD NOT be sent. Similarly, the LMA SHOULD NOT send a 143 Heartbeat Request message to a MAG if there is no active binding 144 cache entry created by the MAG. A PMIPv6 node MUST respond to a 145 Heartbeat Request message with a Heartbeat Response message, 146 irrespective of whether there is an active binding cache entry. 148 The HEARTBEAT_INTERVAL SHOULD NOT be configured to a value less than 149 30 seconds. Sending heartbeat messages too often may become an 150 overhead on the path between the MAG and the LMA. The 151 HEARTBEAT_INTERVAL can be set to a much larger value on the MAG and 152 the LMA, if required, to reduce the burden of sending periodic 153 heartbeat messages. 155 If the LMA or the MAG do not support the heartbeat messages, they 156 respond with a Binding Error message with status set to '2' 157 (unrecognized MH type value) as described in [RFC3775]. When the 158 Binding Error message with status set to '2' is received in response 159 to Heartbeat Request message, the initiating MAG or the LMA MUST NOT 160 use heartbeat messages with the other end again. 162 If a PMIPv6 node has detected that a peer PMIPv6 node has failed or 163 restarted without retaining the PMIPv6 session state, it should mark 164 the corresponding binding update list or binding cache entries as 165 invalid. The PMIPv6 node may also take other actions which are 166 outside the scope of this document. 168 The detection of failures and restarts events may be signaled to 169 network operators by using asynchronous notifications. Future work 170 may define such notifications in a SMIv2 Management Information Base 171 (MIB) module. 173 3.1. Failure Detection 175 A PMIPv6 node, (MAG or LMA) matches every received Heartbeat Response 176 to the Heartbeat Request sent using the sequence number. Before 177 sending the next Heartbeat Request, it increments a local variable 178 MISSING_HEARTBEAT if it has not received a Heartbeat Response for the 179 previous request. When this local variable MISSING_HEARTBEAT exceeds 180 a configurable parameter MISSING_HEARTBEATS_ALLOWED, the PMIPv6 node 181 concludes that the peer PMIPv6 node is not reachable. If a Heartbeat 182 Response message is received, the MISSING_HEARTBEATS counter is 183 reset. 185 3.2. Restart Detection 187 The section describes a mechanism for detecting failure recovery 188 without session persistence. In case the LMA or the MAG crashes and 189 re-boots and loses all state with respect to the PMIPv6 sessions, it 190 would be beneficial for the peer PMIPv6 node to discover the failure 191 and the loss of session state and establish the sessions again. 193 Each PMIPv6 node (both the MAG and LMA) MUST maintain a monotonically 194 increasing Restart Counter that is incremented every time the node 195 re-boots and looses PMIPv6 session state. The counter MUST NOT be 196 incremented if the recovery happens without losing state for the 197 PMIPv6 sessions active at the time of failure. This counter MUST be 198 treated as state that is preserved across reboots. A PMIPv6 node 199 includes a Restart Counter mobility option, described in Section 3.4 200 in an Heartbeat Response message to indicate the current value of the 201 Restart Counter. Each PMIPv6 node MUST also store the Restart 202 Counter for all the peer PMIPv6 nodes that it has sessions with 203 currently. Storing the Restart Counter values for peer PMIPv6 nodes 204 does not need to be preserved across reboots. 206 The PMIPv6 node that receives the Heartbeat Response message compares 207 the Restart Counter value with the previously received value. If the 208 value is different, the receiving node assumes that the peer PMIPv6 209 node had crashed and recovered. If the Restart Counter value changes 210 or if there was no previously stored value, the new value is stored 211 by the receiving PMIPv6 node. 213 If a PMIPv6 node restarts and looses PMIPv6 session state, it SHOULD 214 send an unsolicited Heartbeat Response message with an incremented 215 Restart Counter to all the PMIPv6 nodes that had previously 216 established PMIPv6 sessions. Note that this is possible only when 217 the PMIPv6 node is capable of storing information about the peers 218 across reboots. The unsolicited Heartbeat Response message allows 219 the peer PMIPv6 nodes to quickly discover the restart. The sequence 220 number field in the unsolicited Heartbeat Response is ignored and no 221 response is necessary; the nodes will synchronize during the next 222 Request and Response exchange. 224 3.3. Heartbeat Message 226 The Heartbeat Message is based on the Mobility Header defined in 227 Section 6.1 of [RFC3775]. The 'MH type' field in the Mobility Header 228 indicates that it is a Heartbeat Message. The value MUST be set to 229 . This document does not make any other changes to the 230 Mobility Header message. Please refer to [RFC3775] for a description 231 of the fields in the Mobility Header Message. 233 0 1 2 3 234 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 1 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 | Payload Proto | Header Len | MH Type | Reserved | 237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 238 | Checksum | | 239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 240 | | 241 . . 242 . Message Data . 243 . . 244 | | 245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 247 Figure 1: Mobility Header Message Format 249 The Heartbeat Message follows the 'Checksum' field in the above 250 message. The following illustrates the message format for the 251 Heartbeat Mobility Header message. 253 0 1 2 3 254 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 1 255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 | Reserved |U|R| 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 | Sequence Number | 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | | 261 . . 262 . Mobility options . 263 . . 264 | | 265 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 267 Figure 2: Heartbeat Message Format 269 Reserved 271 Set to 0 and ignored by the receiver. 273 'U' 275 Set to 1 in Unsolicited Heartbeat Response. Otherwise set to 0. 277 'R' 279 A 1-bit flag that indicates whether the message is a request or a 280 response. When the 'R' flag is set to 0, it indicates that the 281 Heartbeat message is a request. When the 'R' flag is set to 1, it 282 indicates that the Heartbeat message is a response. 284 Sequence Number 286 A 32-bit sequence number used for matching the request to the 287 reply. 289 Mobility Options 291 Variable-length field of such length that the complete Mobility 292 Header is an integer multiple of 8 octets long. This field 293 contains zero or more TLV-encoded mobility options. The receiver 294 MUST ignore and skip any options which it does not understand. At 295 the time of writing this document, the Restart Counter Mobility 296 Option, described in Section 3.4, is the only valid option in this 297 message. 299 3.4. Restart Counter Mobility Option 301 The following shows the message format for a new mobility option for 302 carrying the Restart Counter Value in the Heartbeat message. The 303 Restart Counter Mobility Option is only valid in a Heartbeat Response 304 message. It has an alignment requirement of 4n+2. 306 0 1 2 3 307 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 1 308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 309 | Type | Length | 310 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 311 | Restart Counter | 312 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 314 Figure 3: Restart Counter Mobility Option 316 Type 318 A 8-bit field that indicates that it is a Restart Counter mobility 319 option. It MUST be set to . 321 Length 323 A 8-bit field that indicates the length of the option in octets 324 excluding the 'Type' and 'Length' fields. It is set to '4'. 326 Restart Counter 328 A 32-bit field that indicates the current Restart Counter value. 330 4. Exchanging Heartbeat Messages over an IPv4 Transport Network 332 In some deployments, the network between the MAG and the LMA may not 333 be capable of transporting IPv6 packets. In this case, the Heartbeat 334 messages are tunneled over IPv4. If the Proxy Binding Update and 335 Proxy Binding Acknowledgment messages are sent using UDP 336 encapsulation to traverse NATs, then the Heartbeat messages are also 337 sent with UDP encapsulation. The UDP port used would be the same as 338 the port used for the Proxy Binding Update and Proxy Binding 339 Acknowledgement messages. For more details on tunneling Proxy Mobile 340 IPv6 signaling messages over IPv4, see 341 [I-D.ietf-netlmm-pmip6-ipv4-support]. 343 5. Configuration Variables 345 The LMA and the MAG must allow the following variables to be 346 configurable. 348 HEARTBEAT_INTERVAL 350 This variable is used to set the time interval in seconds between 351 two consecutive Heartbeat Request messages. The default value is 352 60 seconds. It SHOULD NOT be set to less than 30 seconds or 353 larger than 3600 seconds. 355 MISSING_HEARTBEATS_ALLOWED 357 This variable indicates the maximum number of consecutive 358 Heartbeat Request messages that a PMIPv6 node did not receive a 359 response for before concluding that the peer PMIPv6 node is not 360 reachable. The default value for this variable is 3. 362 6. Security Considerations 364 The heartbeat messages are just used for checking reachability 365 between the MAG and the LMA. They do not carry information that is 366 useful for eavesdroppers on the path. Therefore, confidentiality 367 protection is not required. Integrity protection using IPsec 368 [RFC4301] for the heartbeat messages MUST be supported on the MAG and 369 the LMA. RFC 5213 [RFC5213] describes how to protect the Proxy 370 Binding Update and Acknowledgment signaling messages with IPsec. The 371 Heartbeat message defined in this specification is merely another 372 subtype of the same Mobility Header protocol that is already being 373 protected by IPsec. Therefore, protecting this additional message is 374 possible using the mechanisms and security policy models from these 375 RFCs. The security policy database entries should use the new MH 376 Type, the Heartbeat Message, for the MH Type selector. 378 If dynamic key negotiation between the MAG and the LMA is required, 379 IKEv2 [RFC4306] should be used. 381 7. IANA Considerations 383 The Heartbeat message defined in Section 3.3 must have the type value 384 allocated from the same space as the 'MH Type' name space in the 385 Mobility Header defined in RFC 3775 [RFC3775]. 387 The Restart Counter mobility option defined in Section 3.4 must have 388 the type value allocated from the same name space as the Mobility 389 Options defined in RFC 3775 [RFC3775]. 391 8. Acknowledgments 393 A heartbeat mechanism for a network-based mobility management 394 protocol was first described in [I-D.giaretta-netlmm-dt-protocol]. 395 The authors would like to thank the members of a NETLMM design team 396 that produced that document. The mechanism described in this 397 document also derives from the path management mechanism described in 398 [GTP]. 400 We would like to thank Alessio Casati for first suggesting a fault 401 handling mechanism for Proxy Mobile IPv6. 403 9. References 404 9.1. Normative References 406 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 407 Requirement Levels", BCP 14, RFC 2119, March 1997. 409 [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., 410 and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 412 [I-D.ietf-netlmm-pmip6-ipv4-support] 413 Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy 414 Mobile IPv6", draft-ietf-netlmm-pmip6-ipv4-support-08 415 (work in progress), January 2009. 417 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 418 Internet Protocol", RFC 4301, December 2005. 420 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", 421 RFC 4306, December 2005. 423 [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support 424 in IPv6", RFC 3775, June 2004. 426 9.2. Informative References 428 [I-D.giaretta-netlmm-dt-protocol] 429 Giaretta, G., "The NetLMM Protocol", 430 draft-giaretta-netlmm-dt-protocol-02 (work in progress), 431 October 2006. 433 [GTP] 3rd Generation Partnership Project, "3GPP Technical 434 Specification 29.060 V7.6.0: "Technical Specification 435 Group Core Network and Terminals; General Packet Radio 436 Service (GPRS); GPRS Tunnelling Protocol (GTP) across the 437 Gn and Gp interface (Release 7)"", July 2007. 439 Authors' Addresses 441 Vijay Devarapalli 442 WiChorus 443 3950 North First Street 444 San Jose, CA 95134 445 USA 447 Email: vijay@wichorus.com 448 Rajeev Koodli 449 Starent Networks 450 USA 452 Email: rkoodli@starentnetworks.com 454 Heeseon Lim 455 Stoke 456 5403 Betsy Ross Drve 457 Santa Clara, CA 95054 458 USA 460 Email: hlim@stoke.com 462 Nishi Kant 463 Stoke 464 5403 Betsy Ross Drive 465 Santa Clara, CA 95054 466 USA 468 Email: nishi@stoke.com 470 Suresh Krishnan 471 Ericsson 472 8400 Decarie Blvd. 473 Town of Mount Royal, QC 474 Canada 476 Email: suresh.krishnan@ericsson.com 478 Julien Laganier 479 DOCOMO Euro-Labs 480 Landsbergerstrasse 312 481 Munich, D-80687 482 Germany 484 Email: julien.IETF@laposte.net