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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3775 (Obsoleted by RFC 6275) == Outdated reference: A later version (-18) exists of draft-ietf-netlmm-pmip6-ipv4-support-17 Summary: 3 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group H. Yokota 3 Internet-Draft KDDI Lab 4 Intended status: Standards Track K. Chowdhury 5 Expires: May 22, 2010 R. Koodli 6 Starent Networks 7 B. Patil 8 Nokia 9 F. Xia 10 Huawei USA 11 November 18, 2009 13 Fast Handovers for Proxy Mobile IPv6 14 draft-ietf-mipshop-pfmipv6-10.txt 16 Abstract 18 Mobile IPv6 (MIPv6) [RFC3775] provides a mobile node with IP mobility 19 when it performs a handover from one access router to another and 20 fast handovers for Mobile IPv6 (FMIPv6) [RFC5568] are specified to 21 enhance the handover performance in terms of latency and packet loss. 22 While MIPv6 (and FMIPv6 as well) requires the participation of the 23 mobile node in the mobility-related signaling, Proxy Mobile IPv6 24 (PMIPv6) [RFC5213] provides IP mobility to mobile nodes that either 25 have or do not have MIPv6 functionality without such involvement. 26 Nevertheless, the basic performance of PMIPv6 in terms of handover 27 latency and packet loss is considered not any different from that of 28 MIPv6. 30 When the fast handover is considered in such an environment, several 31 modifications are needed to FMIPv6 to adapt to the network-based 32 mobility management. This document specifies the usage of Fast 33 Mobile IPv6 (FMIPv6) when Proxy Mobile IPv6 is used as the mobility 34 management protocol. Necessary extensions are specified for FMIPv6 35 to support the scenario when the mobile node does not have IP 36 mobility functionality and hence is not involved with either MIPv6 or 37 FMIPv6 operations. 39 Status of this Memo 41 This Internet-Draft is submitted to IETF in full conformance with the 42 provisions of BCP 78 and BCP 79. 44 Internet-Drafts are working documents of the Internet Engineering 45 Task Force (IETF), its areas, and its working groups. Note that 46 other groups may also distribute working documents as Internet- 47 Drafts. 49 Internet-Drafts are draft documents valid for a maximum of six months 50 and may be updated, replaced, or obsoleted by other documents at any 51 time. It is inappropriate to use Internet-Drafts as reference 52 material or to cite them other than as "work in progress." 54 The list of current Internet-Drafts can be accessed at 55 http://www.ietf.org/ietf/1id-abstracts.txt. 57 The list of Internet-Draft Shadow Directories can be accessed at 58 http://www.ietf.org/shadow.html. 60 This Internet-Draft will expire on May 22, 2010. 62 Copyright Notice 64 Copyright (c) 2009 IETF Trust and the persons identified as the 65 document authors. All rights reserved. 67 This document is subject to BCP 78 and the IETF Trust's Legal 68 Provisions Relating to IETF Documents 69 (http://trustee.ietf.org/license-info) in effect on the date of 70 publication of this document. Please review these documents 71 carefully, as they describe your rights and restrictions with respect 72 to this document. Code Components extracted from this document must 73 include Simplified BSD License text as described in Section 4.e of 74 the Trust Legal Provisions and are provided without warranty as 75 described in the BSD License. 77 This document may contain material from IETF Documents or IETF 78 Contributions published or made publicly available before November 79 10, 2008. The person(s) controlling the copyright in some of this 80 material may not have granted the IETF Trust the right to allow 81 modifications of such material outside the IETF Standards Process. 82 Without obtaining an adequate license from the person(s) controlling 83 the copyright in such materials, this document may not be modified 84 outside the IETF Standards Process, and derivative works of it may 85 not be created outside the IETF Standards Process, except to format 86 it for publication as an RFC or to translate it into languages other 87 than English. 89 Table of Contents 91 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 4 92 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 93 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 94 4. Proxy-based FMIPv6 Protocol Overview . . . . . . . . . . . . . 7 95 4.1. Protocol Operation . . . . . . . . . . . . . . . . . . . . 8 96 4.2. Inter-AR Tunneling Operation . . . . . . . . . . . . . . . 15 97 4.3. IPv4 Support Considerations . . . . . . . . . . . . . . . 17 98 5. PMIPv6-related Fast Handover Issues . . . . . . . . . . . . . 18 99 5.1. Manageability Considerations . . . . . . . . . . . . . . . 18 100 5.2. Expedited Packet Transmission . . . . . . . . . . . . . . 18 101 6. Message Formats . . . . . . . . . . . . . . . . . . . . . . . 20 102 6.1. Mobility Header . . . . . . . . . . . . . . . . . . . . . 20 103 6.1.1. Handover Initiate (HI) . . . . . . . . . . . . . . . . 20 104 6.1.2. Handover Acknowledge (HAck) . . . . . . . . . . . . . 22 105 6.2. Mobility Options . . . . . . . . . . . . . . . . . . . . . 24 106 6.2.1. Context Request Option . . . . . . . . . . . . . . . . 24 107 6.2.2. Local Mobility Anchor Address (LMAA) Option . . . . . 25 108 6.2.3. Mobile Node Interface Identifier (MN IID) Option . . . 26 109 6.2.4. Home Network Prefix Option . . . . . . . . . . . . . . 27 110 6.2.5. Link-local Address Option . . . . . . . . . . . . . . 27 111 6.2.6. GRE Key Option . . . . . . . . . . . . . . . . . . . . 27 112 6.2.7. IPv4 Address Option . . . . . . . . . . . . . . . . . 27 113 6.2.8. Vendor-Specific Mobility Option . . . . . . . . . . . 27 114 7. Security Considerations . . . . . . . . . . . . . . . . . . . 28 115 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 116 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30 117 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31 118 10.1. Normative References . . . . . . . . . . . . . . . . . . . 31 119 10.2. Informative References . . . . . . . . . . . . . . . . . . 31 120 Appendix A. Applicable Use Cases . . . . . . . . . . . . . . . . 32 121 A.1. PMIPv6 Handoff Indication . . . . . . . . . . . . . . . . 32 122 A.2. Local Routing . . . . . . . . . . . . . . . . . . . . . . 32 123 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 34 124 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39 126 1. Requirements notation 128 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 129 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 130 document are to be interpreted as described in [RFC2119]. 132 2. Introduction 134 Proxy Mobile IPv6 [RFC5213] provides IP mobility to a mobile node 135 that does not support Mobile IPv6 [RFC3775] mobile node 136 functionality. A proxy agent in the network performs the mobility 137 management signaling on behalf of the mobile node. This model 138 transparently provides mobility for mobile nodes within a PMIPv6 139 domain. Nevertheless, the basic performance of PMIPv6 in terms of 140 handover latency and packet loss is considered not any different from 141 that of Mobile IPv6. 143 Fast Handovers for Mobile IPv6 (FMIPv6) [RFC5568] describes the 144 protocol to reduce the handover latency for Mobile IPv6 by allowing a 145 mobile node to send packets as soon as it detects a new subnet link 146 and by delivering packets to the mobile node as soon as its 147 attachment is detected by the new access router. This document 148 describes necessary extensions to FMIPv6 to minimize handover delay 149 and packet loss as well as to transfer network-resident context for a 150 PMIPv6 handover. 152 3. Terminology 154 This document reuses terminology from [RFC5213], [RFC5568] and 155 [RFC3775]. The following terms and abbreviations are additionally 156 used in this document. 158 Access Network (AN): 159 A network composed of link-layer access devices such as access 160 points or base stations providing access to an Access Router 161 (AR) connected to it. 163 Previous Access Network (P-AN): 164 The access network to which the Mobile Node (MN) is attached 165 before handover. 167 New Access Network (N-AN): 168 The access network to which the Mobile Node (MN) is attached 169 after handover. 171 Previous Mobile Access Gateway (PMAG): 172 The MAG that manages mobility related signaling for the MN 173 before handover. In this document, the MAG and the Access 174 Router are co-located. 176 New Mobile Access Gateway (NMAG): 177 The MAG that manages mobility related signaling for the MN after 178 handover. In this document, the MAG and the Access Router (AR) 179 are co-located. 181 Local Mobility Anchor (LMA) 182 The topological anchor point for the mobile node's home network 183 prefix(es) and the entity that manages the mobile node's binding 184 state. This specification does not alter any capability or 185 functionality defined in [RFC5213]. 187 HO-Initiate: 188 A generic signaling message, sent from the P-AN to the PMAG that 189 indicates a MN handover. While this signaling is dependent on 190 the access technology, it is assumed that HO-Initiate can carry 191 the information to identify the MN and to assist the PMAG 192 resolve the NMAG and the new access point or the base station to 193 which the MN is moving to. The details of this message are 194 outside the scope of this document. 196 4. Proxy-based FMIPv6 Protocol Overview 198 This specification describes fast handover protocols for the network- 199 based mobility management protocol called Proxy Mobile IP (PMIPv6) 200 [RFC5213]. The core functional entities defined in PMIPv6 are the 201 LMA and the MAG. The LMA is the topological anchor point for the 202 MN's home network prefix(es). The MAG acts as an access router (AR) 203 for the MN and performs the mobility management procedures on its 204 behalf. The MAG is responsible for detecting the MN's movements to 205 and from the access link and for initiating binding registrations to 206 the MN's LMA. If the MAGs can be informed of the detachment and/or 207 attachment of the MN in a timely manner via e.g., the lower layer 208 signaling, it will become possible to optimize the handover 209 procedure, which involves establishing a connection on the new link 210 and signaling between mobility agents, compared to the baseline 211 specification of PMIPv6. 213 In order to further improve the performance during the handover, the 214 PFMIPv6 protocol in this document specifies a bi-directional tunnel 215 between the Previous MAG (PMAG) and the New MAG (NMAG) to tunnel 216 packets meant for the mobile node. In order to enable the NMAG to 217 send the Proxy Binding Update (PBU), the Handover Initiate (HI) and 218 Handover Acknowledge (HAck) messages in [RFC5568] are extended for 219 context transfer, in which parameters such as MN's Network Access 220 Identifier (NAI), Home Network Prefix (HNP), IPv4 Home Address, are 221 transferred from the PMAG. New flags 'P' and 'F' are defined for the 222 HI and HAck messages to distinguish from those in [RFC5568] and to 223 request packet forwarding, respectively. 225 In this document, the Previous Access Router (PAR) and New Access 226 Router (NAR) are interchangeable with the PMAG and NMAG, 227 respectively. The reference network is illustrated in Figure 1. The 228 access networks in the figure (i.e., P-AN and N-AN) are composed of 229 Access Points (APs) defined in [RFC5568], which are often referred to 230 as base stations in cellular networks. 232 Since a MN is not directly involved with IP mobility protocol 233 operations, it follows that the MN is not directly involved with fast 234 handover procedures either. Hence, the messages involving the MN in 235 [RFC5568] are not used when PMIPv6 is in use. More specifically, the 236 Router Solicitation for Proxy Advertisement (RtSolPr), the Proxy 237 Router Advertisement (PrRtAdv), Fast Binding Update (FBU), Fast 238 Binding Acknowledgment (FBack) and the Unsolicited Neighbor 239 Advertisement (UNA) messages are not applicable in the PMIPv6 240 context. 242 +----------+ 243 | LMA | 244 | | 245 +----------+ 246 / \ 247 / \ 248 / \ 249 +........../..+ +..\..........+ 250 . +-------+-+ .______. +-+-------+ . 251 . | PMAG |()_______)| NMAG | . 252 . | (PAR) | . . | (NAR) | . 253 . +----+----+ . . +----+----+ . 254 . | . . | . 255 . ___|___ . . ___|___ . 256 . / \ . . / \ . 257 . ( P-AN ) . . ( N-AN ) . 258 . \_______/ . . \_______/ . 259 . | . . | . 260 . +----+ . . +----+ . 261 . | MN | ----------> | MN | . 262 . +----+ . . +----+ . 263 +.............+ +.............+ 265 Figure 1: Reference network for fast handover 267 4.1. Protocol Operation 269 There are two modes of operation in FMIPv6 [RFC5568]. In the 270 predictive mode of fast handover, a bi-directional tunnel between the 271 PMAG (PAR) and NMAG (NAR) is established prior to the MN's attachment 272 to the NMAG. In the reactive mode, this tunnel establishment takes 273 place after the MN attaches to the NMAG. In order to alleviate the 274 packet loss during a MN's handover (especially when the MN is 275 detached from both links), the downlink packets for the MN need to be 276 buffered either at the PMAG or NMAG, depending on when the packet 277 forwarding is performed. It is hence required that all MAGs have the 278 capability and enough resources to buffer packets for the MNs 279 accommodated by them. The buffer size to be prepared and the rate at 280 which buffered packets are drained are addressed in Section 5.4 of 281 [RFC5568]. Note that the protocol operation specified in the 282 document is transparent to the LMA, hence there is no new functional 283 requirement or change on the LMA. 285 Unlike MIPv6, the MN in the PMIPv6 domain is not involved with IP 286 mobility signaling; therefore, in order for the predictive fast 287 handover to work effectively, it is required that the MN is capable 288 of reporting lower-layer information to the AN at a short enough 289 interval, and the AN is capable of sending the HO-initiate to the 290 PMAG at an appropriate timing. The sequence of events for the 291 predictive fast handover are illustrated in Figure 2. 293 PMAG NMAG 294 MN P-AN N-AN (PAR) (NAR) LMA 295 | | | | | | 296 | Report | | | | | 297 (a) |-(MN ID,-->| | | | | 298 | New AP ID)| | | | | 299 | | HO Initiate | | | 300 (b) | |--(MN ID, New AP ID)-->| | | 301 | | | | | | 302 | | | | | | 303 (c) | | | |----HI---->| | 304 | | | | | | 305 | | | | | | 306 (d) | | | |<---HAck---| | 307 | | | | | | 308 | | | | | | 309 | | | |HI/HAck(optional) | 310 (e) | | | |<- - - - ->| | 311 | | | #=|<===================| 312 (f) | | | #====DL data=>| | 313 | | | | | | 314 (g) ~~~ | | | | | 315 ~~~ | | | | | 316 | MN-AN connection | AN-MAG connection | | 317 (h) |<---establishment---->|<----establishment----->| | 318 | | | (substitute for UNA) | | 319 | | | | | | 320 (i) |<==================DL data=====================| | 321 | | | | | | 322 (j) |===================UL data====================>|=# | 323 | | | #=|<============# | 324 | | | #=====================>| 325 / | | | | | | \ 326 |(k) | | | | |--PBU-->| | 327 | | | | | | | | 328 |(l) | | | | |<--PBA--| | 329 \ | | | | | | / 331 Figure 2: Predictive fast handover for PMIPv6 (PAR initiated) 333 The detailed descriptions are as follows: 335 (a) The MN detects that a handover is imminent and reports the 336 identifications of itself (MN ID) and the New Access Point 337 Identifier (New AP ID) [RFC5568] to which the MN is most likely 338 to move. The MN ID could be the NAI or a Link Layer Address 339 (LLA), or any other suitable identifier. This step is access 340 technology specific. In some cases, the P-AN will determine 341 which AP ID the MN is moving to. 343 (b) The previous access network (P-AN), to which the MN is currently 344 attached, indicates the handover of the MN to the PMAG (PMAG). 345 Detailed definition and specification of this message are 346 outside the scope of this document. 348 (c) The PMAG sends the HI to the NMAG. The HI message MUST have the 349 P flag set and include the MN ID, the HNP(s), the MN IID and the 350 address of the LMA that is currently serving the MN. If there 351 is a valid (non-zero) MN Link-layer Identifier (MN LL-ID), that 352 information MUST also be included. 354 (d) The NMAG sends the HAck back to the PMAG with the P flag set. 356 (e) If it is preferred that the timing of buffering or forwarding 357 should be later than step (c), the NMAG may optionally request 358 the PMAG at a later and appropriate time to buffer or forward 359 packets by setting U flag [RFC5568] or F flag in the HI message, 360 respectively. 362 (f) If the F flag is set in the previous step, a bi-directional 363 tunnel is established between the PMAG and NMAG and packets 364 destined for the MN are forwarded from the PMAG to the NMAG over 365 this tunnel. After decapsulation, those packets may be buffered 366 at the NMAG. If the connection between the N-AN and NMAG has 367 already been established, those packets may be forwarded towards 368 the N-AN, which then becomes responsible for them (e.g., 369 buffering or delivering depending on the condition of the MN's 370 attachment); this is access technology specific. 372 (g) The MN undergoes handover to the New Access Network (N-AN). 374 (h) The MN establishes a physical link connection with the N-AN 375 (e.g., radio channel assignment), which in turn triggers the 376 establishment of a link-layer connection between the N-AN and 377 NMAG if not yet established. An IP layer connection setup may 378 be performed at this time (e.g., PPP IPv6CP) or at a later time 379 (e.g., stateful or stateless auto address configuration). This 380 step can be a substitute for the UNA in [RFC5568]. If the NMAG 381 acquires a valid new MN LL-ID via the N-AN and a valid old MN 382 LL-ID from the PMAG at step (c), these IDs SHOULD be compared to 383 determine whether the same interface is used before and after 384 handover. When the connection between the MN and NMAG is PPP 385 and the same interface is used for the handover, the NMAG SHOULD 386 confirm that the same interface identifier (IID), which is 387 transferred by the MN-IID option at step (c), is assigned to the 388 MN's interface during the Configure-Request/Ack exchange. 390 (i) The NMAG starts to forward packets destined for the MN via the 391 N-AN. 393 (j) The uplink packets from the MN are sent to the NMAG via the N-AN 394 and the NMAG forwards them to the PMAG. The PMAG then sends the 395 packets to the LMA that is currently serving the MN. 397 (k) The NMAG (NAR) sends the Proxy Binding Update (PBU) to the LMA, 398 whose address is provided in (c). Steps (k) and (l) are not 399 part of the fast handover procedure, but shown for reference. 401 (l) The LMA sends back the Proxy Binding Acknowledgment (PBA) to the 402 NMAG (NMAG). From this time on, the packets to/from the MN go 403 through the NMAG instead of the PMAG. 405 According to Section 4 of [RFC5568], the PMAG establishes a binding 406 between the Previous Care-of Address (PCoA) and New Care-of Address 407 (NCoA) to forward packets for the MN to the NAR, and the NMAG creates 408 a proxy neighbor cache entry to receive those packets for the NCoA 409 before the MN arrives. In the case of PMIPv6, however, the only 410 address that is used by the MN is MN-HoA (Mobile Node's Home 411 Address). Hence the PMAG forwards MN's packets to the NMAG instead 412 of the NCoA. FMIPv4 [RFC4988] specifies forwarding when the MN uses 413 the home address as its on-link address rather than the care-of 414 address. The usage in PMIPv6 is similar to that in FMIPv4, where the 415 address is used by the MN is based on Home Network Prefix. Hence the 416 PMAG forwards MN's packets to the NMAG instead of the NCoA. The NMAG 417 then simply decapsulates those packets and delivers them to the MN. 418 Since the NMAG obtains the Link-layer address (MN LL-ID), the 419 interface identifier (MN-IID) and HNP(s) by the HI, it can create the 420 Neighbor Cache Entry for the MN and deliver packets to it even before 421 the MN can perform Neighbor Discovery. For the uplink packets from 422 the MN after handover in (j), the NMAG forwards the packets to the 423 PMAG through the tunnel established in step (f). The PMAG then 424 decapsulates and sends them to the LMA. 426 The timing of the context transfer and that of packet forwarding may 427 be different. Thus, a new flag 'F' and Option Code values for it in 428 the HI and HAck messages are defined to request forwarding. To 429 request buffering, 'U' flag has already been defined in [RFC5568]. 430 If the PMAG receives the HI message with the F flag set, it starts 431 forwarding packets for the MN. The HI message with the U flag set 432 may be sent earlier if the timing of buffering is different from that 433 of forwarding. If packet forwarding is completed, the PMAG MAY send 434 the HI message with the F flag set and the Option Code value being 2. 435 By this message, the ARs on both ends can tear down the forwarding 436 tunnel synchronously. 438 The IP addresses in the headers of those user packets are summarized 439 below: 441 In Step (f), 443 Inner source address: IP address of the CN 445 Inner destination address: HNP or Mobile Node's IPv4 Home 446 Address (IPv4-MN-HoA) 448 Outer source address: IP address of the PMAG (PAR) 450 Outer destination address: IP address of the NMAG (NAR) 452 In Step (i), 454 Source address: IP address of the CN 456 Destination address: HNP or IPv4-MN-HoA 458 In Step (j), 460 - from the MN to the NMAG, 462 Source address: HNP or IPv4-MN-HoA 464 Destination address: IP address of the CN 466 - from the NMAG to the PMAG, 468 Inner source address: HNP or IPv4-MN-HoA 470 Inner destination address: IP address of the CN 472 Outer source address: IP address of the NMAG (NAR) 474 Outer destination address: IP address of the PMAG (PAR) 476 - from the PMAG to the LMA, 477 Inner source address: HNP or IPv4-MN-HoA 479 Inner destination address: IP address of the CN 481 Outer source address: IP address of the PMAG (PAR) 483 Outer destination address: IP address of the LMA 485 In the case of the reactive handover for PMIPv6, since the MN does 486 not send either the FBU or UNA, it would be more natural that the 487 NMAG sends the HI to the PMAG after the MN has moved to the new link. 488 The NMAG then needs to obtain the information of the PMAG beforehand. 489 Such information could be provided, for example, by the MN sending 490 the AP-ID on the old link and/or by the lower-layer procedures 491 between the P-AN and N-AN. The exact method is not specified in this 492 document. Figure 3 illustrates the reactive fast handover procedures 493 for PMIPv6, where the bi-directional tunnel establishment is 494 initiated by the NMAG. 496 PMAG NMAG 497 MN P-AN N-AN (PAR) (NAR) LMA 498 | | | | | | 499 (a) ~~~ | | | | | 500 ~~~ | | | | | 501 | MN-AN connection | AN-MAG connection | | 502 (b) |<--establishment-->|<-------establishment------>| | 503 |(MN ID, Old AP ID) | (MN ID, Old AP ID) | | 504 | | |(substitute for UNA and FBU)| | 505 | | | | | | 506 | | | | | | 507 (c) | | | |<-----HI-------| | 508 | | | | | | 509 | | | | | | 510 (d) | | | |-----HAck----->| | 511 | | | | | | 512 | | | | | | 513 (e) | | | #=|<=======================| 514 | | | #================>|=# | 515 |<====================DL data======================# | 516 | | | | | | 517 (f) |=====================UL data===================>|=# | 518 | | | #=|<================# | 519 | | | #=========================>| 520 | | | | | | 521 / | | | | | | \ 522 |(g) | | | | |--PBU-->| | 523 | | | | | | | | 524 |(h) | | | | |<--PBA--| | 525 \ | | | | | | / 527 Figure 3: Reactive fast handover for PMIPv6 (NAR initiated) 529 The detailed descriptions are as follows: 531 (a) The MN undergoes handover from the P-AN to the N-AN. The AP-ID 532 on the old link may be provided by the MN to help identify the 533 PMAG on the new link. 535 (b) The MN establishes a connection (e.g., radio channel) with the 536 N-AN, which triggers the establishment of the connection between 537 the N-AN and NMAG. The MN ID is transferred to the NMAG for the 538 subsequent procedures. The AP-ID on the old link may also be 539 provided by the MN to help identify the PMAG on the new link. 540 This can be regarded as a substitute for the UNA and FBU. 542 (c) The NMAG sends the HI to the PMAG. The HI message MUST have the 543 P flag set and include the MN ID. The Context Request Option 544 MAY be included to request additional context information on the 545 MN to the PMAG. 547 (d) The PMAG sends the HAck back to the NMAG with the P flag set. 548 The HAck message MUST include the HNP(s) and/or IPv4-MN-HoA that 549 is corresponding to the MN ID in the HI message and SHOULD 550 include the MN LL-ID, only if it is valid (non zero), and the 551 LMA address that is currently serving the MN. The context 552 information requested by the NMAG MUST be included. If the 553 requested context is not available for some reason, the PMAG 554 MUST return the HAck with the Code value 131. If the F flag is 555 set in the HI at step (c) and forwarding is nevertheless not 556 executable for some reason, the PMAG MUST return the HAck with 557 the Code value 132. 559 (e) If the F flag in the HI is set at step (c), a bi-directional 560 tunnel is established between the PMAG and NMAG and packets 561 destined for the MN are forwarded from the PMAG to the NMAG over 562 this tunnel. After decapsulation, those packets are delivered 563 to the MN via the N-AN. 565 (f) The uplink packets from the MN are sent to the NMAG via the N-AN 566 and the NMAG forwards them to the PMAG. The PMAG then sends the 567 packets to the LMA that is currently serving the MN. 569 Steps (g)-(h) are the same as (k)-(l) in the predictive fast handover 570 procedures. 572 In step (c), The IP address of the PMAG needs to be resolved by the 573 NMAG to send the HI to the PMAG. This information may come from the 574 N-AN or some database that the NMAG can access. 576 4.2. Inter-AR Tunneling Operation 578 When the PMAG (PAR) or NMAG (NAR), depending on the fast handover 579 mode, receives the HI message with the F flag set, it prepares to 580 send/receive the MN's packets to/from the other MAG and returns the 581 HAck message with the same sequence number. The both MAGs SHOULD 582 support the following encapsulation modes for the user packets, which 583 are also defined for the tunnel between the LMA and MAG: 585 o IPv4-or-IPv6-over-IPv6 [IPv4PMIPv6] 587 o IPv4-or-IPv6-over-IPv4 [IPv4PMIPv6] 588 o IPv4-or-IPv6-over-IPv4-UDP [IPv4PMIPv6] 590 o TLV-header UDP tunneling [GREKEY] 592 o GRE tunneling with or without GRE key(s) [GREKEY] 594 The PMAG and the NMAG MUST use the same tunneling mechanism for the 595 data traffic tunneled between them. The encapsulation mode to be 596 employed SHOULD be configurable. This specification recommends the 597 following: 599 1. As the default behavior, the inter-MAG tunnel uses the same 600 encapsulation mechanism as that for the PMIPv6 tunnel between the 601 LMA and the MAGs. The PMAG and NMAG automatically start using 602 the same encapsulation mechanism without a need for a special 603 configuration on the MAGs or a dynamic tunneling mechanism 604 negotiation between them. 606 2. Configuration on the MAGs can override the default mechanism 607 specified in #1 above. The PMAG and NMAG MUST be configured with 608 the same mechanism and this configuration is most likely to be 609 uniform throughout the PMIPv6 domain. If the packets on the 610 PMIPv6 tunnel cannot be uniquely mapped on to the configured 611 inter-MAG tunnel, this scenario is not applicable and scenario #3 612 below SHOULD directly be applied. 614 3. An implicit or explicit tunnel negotiation mechanism between the 615 MAGs can override the default mechanism specified in #1 above. 616 The employed tunnel negotiation mechanism is outside the scope of 617 this document. 619 The necessary information MUST be transferred in the HI/HAck messages 620 to distinguish MN's packets for forwarding in advance or at this 621 time. Such information includes the HNP(s) (or IPv4-MN-HoA) and/or 622 GRE key(s). In the case of GRE tunneling with GRE keys being used, 623 for each mobility session, the NMAG selects the GRE key for the 624 downlink packets and the PMAG selects the GRE key for the uplink 625 packets. These GRE keys are exchanged between the PMAG and the NMAG 626 using the GRE Key option as described in [GREKEY], e.g., In the case 627 of the reactive mode as shown in Figure 3, the DL GRE key is 628 communicated in the HI message while the UL GRE key is sent in the 629 HAck message. For the downlink packets, the PMAG redirects MN's 630 packets from the LMA towards the NMAG and if the MN is ready to 631 receive those packets or the N-AN can handle them regardless of the 632 state of the MN, the NMAG should immediately send them towards the 633 N-AN; otherwise it should buffer them until the MN is ready. For the 634 uplink packets, the NMAG SHOULD reverse-tunnel them from the MN 635 towards the PMAG and the PMAG sends them to the LMA. 637 When the PMAG or NMAG receives the HI message with the U flag set, it 638 prepares to buffer the MN's packets and returns the HAck message with 639 the same sequence number. It MUST be followed by another HI message 640 with the F flag set at an appropriate time to forward the buffered 641 packets. 643 If the MAG that received the HI message encounters an erroneous 644 situation (e.g., insufficient buffer space), it SHOULD immediately 645 send the HAck message with the cause of the error and cancel all 646 tunneling operation. 648 4.3. IPv4 Support Considerations 650 The motivation and usage scenarios of IPv4 protocol support by PMIPv6 651 are described in [IPv4PMIPv6]. The scope of IPv4 support covers the 652 following two features: 654 o IPv4 Home Address Mobility Support, and 656 o IPv4 Transport Support. 658 As for IPv4 Home Address Mobility Support, the MN acquires IPv4 Home 659 Address (IPv4-MN-HoA) and in the case of handover, the PMAG needs to 660 transfer IPv4-MN-HoA to the NMAG, which is the inner destination 661 address of the packets forwarded on the downlink. For this purpose, 662 IPv4 Address Option described in Section 6.2.7 is used. In order to 663 provide IPv4 Transport Support, the NMAG needs to know the IPv4 664 address of the LMA (IPv4-LMAA) to send PMIPv6 signaling messages to 665 the LMA in the IPv4 transport network. For this purpose, a new 666 option called LMA Address (LMAA) Option is defined in Section 6.2.2 667 so as to convey IPv4-LMAA from the PMAG to NMAG. 669 5. PMIPv6-related Fast Handover Issues 671 5.1. Manageability Considerations 673 This specification does not require any additional IP-level 674 functionality on the LMA and the MN running in the PMIPv6 domain. A 675 typical network interface that the MN could be assumed to have is one 676 with the cellular network, where the network controls the movement of 677 the MN. Different types of interfaces could be involved such as 678 different generations (3G and 3.9G) or different radio access 679 systems. This specification supports a MN with the single radio 680 mode, where only one interface is active at any given time. The 681 assigned IP address is preserved whether the physical interface 682 changes or not and the MN can identify which interface should be used 683 if there are multiple ones. 685 5.2. Expedited Packet Transmission 687 The protocol specified in this document enables the NMAG to obtain 688 parameters which would otherwise be available only by communicating 689 with the LMA. For instance, the HNP(s) and/or IPv4-MN-HoA of a MN 690 are made available to the NMAG through context transfer. This allows 691 the NMAG to perform some procedures that may be beneficial. The 692 NMAG, for example, could send a Router Advertisement (RA) with the 693 HNP option to the MN as soon as its link attachment is detected 694 (e.g., via receipt of a Router Solicitation message). Such an RA is 695 recommended, for example, in scenarios where the MN uses a new radio 696 interface while attaching to the NMAG; since the MN does not have 697 information regarding the new interface, it will not be able to 698 immediately send packets without first receiving an RA with HNP(s). 699 Especially, in the reactive fast handover, the NMAG gets to know the 700 HNP(s) assigned to the MN on the previous link at step (d) in 701 Figure 3. In order to reduce the communication disruption time, the 702 NMAG SHOULD expect the MN to keep using the same HNP and to send 703 uplink packets before that step upon the MN's request. However, if 704 the HAck from the PMAG returns a different HNP or the subsequent 705 PMIPv6 binding registration for the HNP fails for some reason, then 706 the NMAG MUST withdraw the advertised HNP by sending another RA with 707 zero prefix lifetime for the HNP in question. This operation is the 708 same as described in Section 6.12 of [RFC5213]. 710 The protocol specified in this document is applicable regardless of 711 whether link-layer addresses are used between a MN and its access 712 router. A MN should be able to continue sending packets on the 713 uplink even when it changes link. When link-layer addresses are 714 used, the MN performs Neighbor Unreachability Detection (NUD) 715 [RFC4861], after attaching to a new link, probing the reachability of 716 its default router. The new router should respond to the NUD probe, 717 providing its link-layer address in the solicited Neighbor 718 Advertisement, which is common in the PMIPv6 domain. Implementations 719 should allow the MN to continue to send uplink packets while it is 720 performing NUD. 722 6. Message Formats 724 This document defines new Mobility Header messages for the extended 725 HI and Hack and new mobility options for conveying context 726 information. 728 6.1. Mobility Header 730 6.1.1. Handover Initiate (HI) 732 This section defines extensions to the HI message in [RFC5568]. The 733 format of the Message Data field in the Mobility Header is as 734 follows: 736 0 1 2 3 737 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 1 738 +-------------------------------+ 739 | Sequence # | 740 +-+-+-+-+-------+---------------+-------------------------------+ 741 |S|U|P|F|Resv'd | Code | | 742 +-+-+-+-+-------+---------------+ | 743 | | 744 . . 745 . Mobility options . 746 . . 747 | | 748 +---------------------------------------------------------------+ 749 (Note:P=1) 751 IP Fields: 753 Source Address 755 The IP address of PMAG or NMAG 757 Destination Address 759 The IP address of the peer MAG 761 Message Data: 763 Sequence # Same as [RFC5568]. 765 S flag Defined in [RFC5568] and MUST be set to zero in this 766 specification. 768 U flag Buffer flag. Same as [RFC5568]. 770 P flag Proxy flag. Used to distinguish the message from that 771 defined in [RFC5568] and MUST be set in all new message 772 formats defined in this document when using this protocol 773 extension. 775 F flag Forwarding flag. Used to request to forward the packets 776 for the MN. 778 Reserved Same as [RFC5568]. 780 Code [RFC5568] defines this field and its values 0 and 1. In 781 this specification, with the P flag set, this field can 782 be set to zero by default or the following values: 784 2: Indicate the completion of forwarding 786 3: All available context transferred 788 Code value 3 is set when the transfer of all necessary 789 context information is completed with this message. This 790 Code value is used in both cases where the context 791 information is fragmented into several pieces and the 792 last fragment is contained in this message and where the 793 whole information is transferred in one piece. 795 Mobility options: 797 This field contains one or more mobility options, whose encoding and 798 formats are defined in [RFC3775]. 800 Requested option 801 In order to uniquely identify the target MN, the MN 802 Identifier MUST be contained in the Mobile Node Identifier 803 Option. 805 The transferred context MUST be for one MN per message. In addition, 806 the NMAG can request necessary mobility options by the Context 807 Request Option defined in this document. 809 Context Request Option 811 This option MAY be present to request context information 812 typically by the NMAG to the PMAG in the NAR-initiated fast 813 handover. 815 6.1.2. Handover Acknowledge (HAck) 817 This section defines extensions to the HAck message in[RFC5568]. The 818 format of the Message Data field in the Mobility Header is as 819 follows: 821 0 1 2 3 822 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 1 823 +-------------------------------+ 824 | Sequence # | 825 +-+-+-+---------+---------------+-------------------------------+ 826 |U|P|F|Reserved | Code | | 827 +-+-+-+---------+---------------+ | 828 | | 829 . . 830 . Mobility options . 831 . . 832 | | 833 +---------------------------------------------------------------+ 834 (Note:P=1) 836 IP Fields: 838 Source Address 840 Copied from the destination address of the 841 Handover Initiate message to which this message 842 is a response. 844 Destination Address 846 Copied from the source address of the Handover 847 Initiate message to which this message is a 848 response. 850 Message Data: 852 The usages of Sequence # and Reserved fields are exactly the same as 853 those in [RFC5568]. 855 U flag Same as defined in Section 6.1.1. 857 P flag Used to distinguish the message from that defined in 858 [RFC5568] and MUST be set in all new message formats 859 defined in this document when using this protocol 860 extension. 862 F flag Same as defined in Section 6.1.1. 864 Code 865 Code values 0 through 4 and 128 through 130 are defined 866 in [RFC5568]. In this specification, the meaning of Code 867 value 0 is modified, 128 through 130 are reused, and 5, 868 6, 131 and 132 are newly defined. 870 0: Handover Accepted or Successful 872 5: Context Transfer Accepted or Successful 874 6: All available Context Transferred 876 128: Handover Not Accepted, reason unspecified 878 129: Administratively prohibited 880 130: Insufficient resources 882 131: Requested Context Not Available 884 132: Forwarding Not Available 886 Mobility options: 888 This field contains one or more mobility options, whose encoding and 889 formats are defined in [RFC3775]. The mobility option that uniquely 890 identifies the target MN MUST be copied from the corresponding HI 891 message and the transferred context MUST be for one MN per message. 893 Requested option(s) All the context information requested by the 894 Context Request Option in the HI message SHOULD be present 895 in the HAck message. The other cases are described below. 897 In the case of the PAR-initiated fast handover, when the PMAG sends 898 the HI message to the NMAG with the context information and the NMAG 899 successfully receives it, the NMAG returns the HAck message with Code 900 value 5. In the case of the NAR-initiated fast handover, when the 901 NMAG sends the HI message to the PMAG with or without Context Request 902 Option, the PMAG returns the HAck message with the requested or 903 default context information (if any). If all available context 904 information is transferred, the PMAG sets the Code value in the HAck 905 message to 6. If more context information is available, the PMAG 906 sets the Code value in the HAck to 5 and the NMAG MAY send new HI 907 message(s) to retrieve the rest of the available context information. 908 If none of the requested context information is available, the PMAG 909 returns the HAck message with Code value 131 without any context 910 information. 912 6.2. Mobility Options 914 6.2.1. Context Request Option 916 This option is sent in the HI message to request context information 917 on the MN. If a default set of context information is defined and 918 always sufficient, this option is not used. This option is more 919 useful to retrieve additional or dynamically selected context 920 information. 922 Context Request Option is typically used for the reactive (NAR- 923 initiated) fast handover mode to retrieve the context information 924 from the PMAG. When this option is included in the HI message, all 925 the requested context information SHOULD be included in the HAck 926 message in the corresponding mobility option(s) (e.g., HNP, LMAA or 927 MN IID mobility options). 929 The default context information to request is the Home Network Prefix 930 Option. If the Mobile Node link-layer is available and used, the 931 Mobile Node Link-layer Identifier Option MUST also be requested. 933 0 1 2 3 934 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 1 935 +---------------+---------------+---------------+---------------+ 936 | Option-Type | Option-Length | Reserved | 937 +---------------+---------------+-------------------------------+ 938 | Req-type-1 | Req-length-1 | Req-type-2 | Req-length-2 | 939 +---------------------------------------------------------------+ 940 | Req-type-3 | Req-length-3 | Req-option-3 | 941 +---------------------------------------------------------------+ 942 | ... | 944 Option-Type TBD1 946 Option-Length The length in octets of this option, not including the 947 Option Type and Option Length fields. 949 Reserved This field is unused. It MUST be initialized to zero 950 by the sender and MUST be ignored by the receiver. 952 Req-type-n The type value for the n'th requested option. 954 Req-length-n The length of the n'th requested option excluding the 955 Req-type-n and Req-length-n fields. 957 Req-option-n The optional data to uniquely identify the requested 958 context for the n'th requested option. 960 In the case where there are only Req-type-n and Req-length-n fields, 961 the value of the Req-length-n is set to zero. If additional 962 information besides the Req-type-n is necessary to uniquely specify 963 the requested context, such information follows after the 964 Req-length-n. For example, when the requested contexts start with 965 the HNP Option (type=22), the MN Link-layer ID Option (type=25) and 966 the Vendor-Specific Option (type=19), the requested option format 967 looks as follows: 969 | ... | 970 +---------------+---------------+---------------+---------------+ 971 |Option-Type=CRO| Option-Length | Reserved | 972 +---------------+---------------+---------------+---------------+ 973 | Req-type-N=22 | Req-length-N=0| Req-type-N=25 | Req-length-N=0| 974 +---------------+---------------+-------------------------------+ 975 | Req-type-N=19 | Req-length-N=5| Vendor-ID | 976 +-------------------------------+---------------+---------------+ 977 | Vendor-ID | Sub-Type | | 978 +-----------------------------------------------+ | 979 | ... | 981 The first two options can uniquely identify the requested contexts 982 (i.e., the HNP and MN Link-layer ID) by the Req-type, so the Req- 983 length is set to zero; however, the subsequent Vendor-Specific Option 984 further needs the Vendor-ID and Sub-type to identify the requested 985 context, so these parameters follow and the Req-length is set to 5. 986 Note that the exact values in the Vendor-ID ans Sub-Type follow 987 [RFC5094]. 989 6.2.2. Local Mobility Anchor Address (LMAA) Option 991 This option is used to transfer the Local Mobility Anchor IPv6 992 Address (LMAA) or its IPv4 Address (IPv4-LMAA), with which the MN is 993 currently registered. The detailed definition of the LMAA is 994 described in [RFC5213]. 996 0 1 2 3 997 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 1 998 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 999 | Option-Type | Option-Length | Option-Code | Reserved | 1000 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1001 | Local Mobility Anchor Address ... | 1003 Option-Type TBD2 1005 Option-Length 18 or 6 1007 Option-Code 1009 0 Reserved 1011 1 IPv6 address of the LMA (LMAA) 1013 2 IPv4 address of the LMA (IPv4-LMAA) 1015 Reserved This field is unused. It MUST be initialized to zero 1016 by the sender and MUST be ignored by the receiver. 1018 Local Mobility Anchor Address 1019 If Option-Code is 1, the LMA IPv6 address (LMAA) is 1020 inserted. If Option-Code is 2, the LMA IPv4 address 1021 (IPv4-LMA) is inserted. 1023 6.2.3. Mobile Node Interface Identifier (MN IID) Option 1025 This option is used to transfer the interface identifier of the MN 1026 that is used in the P-AN. 1028 0 1 2 3 1029 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 1030 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1031 | Option-Type | Option-Length | Reserved | 1032 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1033 | | 1034 + Interface Identifier + 1035 | | 1036 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1038 Option-Type TBD3 1040 Option-Length 10 1042 Reserved This field is unused. It MUST be initialized to zero 1043 by the sender and MUST be ignored by the receiver. 1045 Interface Identifier 1046 The Interface Identifier value of the MN that is used 1047 in the P-AN. 1049 6.2.4. Home Network Prefix Option 1051 This option is used to transfer the home network prefix that is 1052 assigned to the MN in the P-AN. The Home Network Prefix Option 1053 defined in [RFC5213] is used for this. 1055 6.2.5. Link-local Address Option 1057 This option is used to transfer the link-local address of the PMAG 1058 (PMAG). The Link-local Address Option defined in [RFC5213] is used 1059 for this. 1061 6.2.6. GRE Key Option 1063 This option is used to transfer the GRE Key for the MN's data flow 1064 over the bi-directional tunnel between the PMAG and NMAG. The 1065 message format of this option follows the GRE Key Option defined in 1066 [GREKEY]. The GRE Key value uniquely identifies each flow and the 1067 sender of this option expects to receive packets of the flow from the 1068 peer AR with this value. 1070 6.2.7. IPv4 Address Option 1072 As described in Section 4.3, if the MN runs in IPv4-only mode or 1073 dual-stack mode, it requires IPv4 home address (IPv4-MN-HoA). This 1074 option is used to transfer the IPv4 home address if assigned on the 1075 previous link. The format of this option follows the IPv4 Home 1076 Address Request Option defined in [IPv4PMIPv6]. 1078 6.2.8. Vendor-Specific Mobility Option 1080 This option is used to transfer any other information defined in this 1081 document. The format and used values of this option follow the 1082 Vendor-Specific Mobility Option defined in [RFC5094]. 1084 7. Security Considerations 1086 Security issues for this document follow those for PMIPv6 [RFC5213] 1087 and FMIPv6 [RFC5568]. In PMIPv6, the MAG and LMA are assumed to 1088 share security associations. In FMIPv6, the access routers (i.e., 1089 the PMAG and NMAG in this document) are assumed to share security 1090 associations. 1092 The Handover Initiate (HI) and Handover Acknowledge (HAck) messages 1093 exchanged between the PMAG and NMAG MUST be protected using end-to- 1094 end security association(s) offering integrity and data origin 1095 authentication. The PMAG and the NMAG MUST implement IPsec [RFC4301] 1096 for protecting the HI and HAck messages. IPsec Encapsulating 1097 Security Payload (ESP) [RFC4303] in transport mode with mandatory 1098 integrity protection SHOULD be used for protecting the signaling 1099 messages. Confidentiality protection SHOULD be used if sensitive 1100 context related to the mobile node is transferred. 1102 IPsec ESP [RFC4303] in tunnel mode SHOULD be used to protect the MN's 1103 packets at the time of forwarding if the link between the PMAG and 1104 NMAG exposes the MN's packets to more threats than if they had 1105 followed their normal routed path. 1107 8. IANA Considerations 1109 This document defines new flags and status codes in the HI and HAck 1110 messages as well as three new mobility options. The Type values for 1111 these mobility options are assigned from the same numbering space as 1112 allocated for the other mobility options defined in [RFC3775]. 1114 Mobility Options 1115 Value Description Reference 1116 ----- ------------------------------------- ------------- 1117 TBD1 Context Request Option Section 6.2.1 1118 TBD2 Local Mobility Anchor Address Option Section 6.2.2 1119 TBD3 Mobile Node Interface Identifier Option Section 6.2.3 1121 Handover Initiate Flags 1122 Flag Value Description Reference 1123 ---- ----- ------------------------------- ------------- 1124 P 0x20 Proxy flag Section 6.1.1 1125 F 0x10 Forwarding flag Section 6.1.1 1127 Handover Acknowlede Flags 1128 Flag Value Description Reference 1129 ---- ----- ------------------------------- ------------- 1130 P 0x40 Proxy flag Section 6.1.2 1131 F 0x20 Forwarding flag Section 6.1.2 1133 Handover Initiate Status Codes 1134 Code Description Reference 1135 ---- -------------------------------------- ------------- 1136 2 Indicate the completion of forwarding Section 6.1.1 1137 3 All available context transferred Section 6.1.1 1139 Handover Acknowledge Status Codes 1140 Code Description Reference 1141 ---- -------------------------------------- ------------- 1142 0 Handover Accepted or Successful Section 6.1.2 1143 5 Context Transfer Accepted or Successful Section 6.1.2 1144 6 All available Context Transferred Section 6.1.2 1145 131 Requested Context Not Available Section 6.1.2 1146 132 Forwarding Not Available Section 6.1.2 1148 9. Acknowledgments 1150 The authors would like to specially thank Vijay Devarapalli and Sri 1151 Gundavelli for their thorough reviews of this document. 1153 The authors would also like to thank Charlie Perkins, Desire Oulai, 1154 Ahmad Muhanna, Giaretta Gerardo, Domagoj Premec, Marco Liebsch, Fan 1155 Zhao, Julien Laganier and Pierrick Seite for their passionate 1156 discussions in the working group mailing list. 1158 10. References 1160 10.1. Normative References 1162 [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., 1163 and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 1165 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1166 Requirement Levels", BCP 14, RFC 2119, March 1997. 1168 [RFC5568] Koodli, R., "Mobile IPv6 Fast Handovers", RFC 5568, 1169 July 2009. 1171 [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support 1172 in IPv6", RFC 3775, June 2004. 1174 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1175 Internet Protocol", RFC 4301, December 2005. 1177 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1178 RFC 4303, December 2005. 1180 [RFC5094] Devarapalli, V., Patel, A., and K. Leung, "Mobile IPv6 1181 Vendor Specific Option", RFC 5094, December 2007. 1183 [IPv4PMIPv6] 1184 Wakikawa, R., Ed. and S. Gundavelli, "IPv4 Support for 1185 Proxy Mobile IPv6", 1186 draft-ietf-netlmm-pmip6-ipv4-support-17.txt, 1187 Semptember 2009. 1189 [GREKEY] Muhanna, A., Ed., "GRE Key Option for Proxy Mobile IPv6", 1190 draft-ietf-netlmm-grekey-option-09.txt, May 2009. 1192 10.2. Informative References 1194 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1195 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1196 September 2007. 1198 [RFC4988] Koodli, R. and C. Perkins, "Mobile IPv4 Fast Handovers", 1199 RFC 4988, October 2007. 1201 Appendix A. Applicable Use Cases 1203 A.1. PMIPv6 Handoff Indication 1205 PMIPv6 [RFC5213] defines the Handoff Indicator Option and describes 1206 the type of the handoff and the values to set to the option. This 1207 document proposes one approach to determining the handoff type by the 1208 NMAG when the handoff of the MN is executed. 1210 According to [RFC5213], the following handoff types are defined: 1212 0) Reserved 1214 1) Attachment over a new interface 1216 2) Handoff between two different interfaces of the mobile node 1218 3) Handoff between mobile access gateways for the same interface 1220 4) Handoff state unknown 1222 5) Handoff state not changed (Re-registration) 1224 Assuming that there is a valid MN Link-layer Identifier (MN LL-ID), 1225 the following solution can be considered. When the NMAG receives the 1226 MN LL-ID from the PMAG in the MN LL-ID option via the HI or HAck 1227 message, the NMAG compares it with the new MN LL-ID that is obtained 1228 from the MN in the N-AN. If these two MN LL-IDs are the same, the 1229 handoff type falls into 3) and the Handoff Indicator value is set to 1230 3. If these two MN LL-IDs are different, the handoff is likely to be 1231 2) since the HI/HAck message exchange implies that this is a handoff 1232 not a multi-homing, therefore the Handoff Indicator value can be set 1233 to 2. If there is no HI/HAck exchange performed prior to the network 1234 attachment of the MN in the N-AN, the NMAG may infer that this is a 1235 multi-homing case and set the Handoff Indicator value to 1. In the 1236 case of re-registration, the MAG, to which the MN is attached, can 1237 determine if the handoff state is not changed, so the MAG can set the 1238 HI value to 5 without any additional information. If none of them 1239 can be assumed or there is no valid MN LL-ID available, the NMAG may 1240 set the value to 4. 1242 A.2. Local Routing 1244 Section 6.10.3 in [RFC5213] describes that if EnableMAGLocalRouting 1245 flag is set, when two mobile nodes are attached to one MAG, the 1246 traffic between them may be locally routed. If one mobile node moves 1247 from this MAG (PMAG) to another MAG (NMAG) and if the PMAG does not 1248 detect the MN's detachment, it will continue to forward packets 1249 locally forever. This situation is more likely to happen in the 1250 reactive fast handover with WLAN access, which does not have the 1251 capability to detect the detachment of the MN in a timely manner. 1252 PFMIPv6 can be applied to handle this case. When the MN attaches to 1253 the NMAG, the NMAG sends the HI message to the PMAG with the 'F' flag 1254 set, which makes the PMAG realize the detachment of the MN and 1255 establish the inter-MAG tunnel. The PMAG immediately stops the local 1256 routing and sends the packets for the MN to the NMAG via that tunnel, 1257 which are then delivered to the MN on the new link. 1259 Appendix B. Change Log 1261 Changes at -00 1263 * Added separate sections for MH and ICMP. 1265 * Clarified usage of HNP and IPv4-MN-HoA throughout the document. 1267 * Added IANA Considerations. 1269 * Added section on Other Considerations, including operation of 1270 uplink packets when using link-layer addresses, multiple 1271 interface usage and transmission of RA to withdraw HNP in the 1272 event of failure of PMIP6 registration. 1274 * Revised Security Considerations. 1276 Changes from -00 to -01 1278 * Removed ICMPv6-based message format. 1280 * Clarified HI/HAck exchange in the predictive mode (step (e) in 1281 Figure 2). 1283 * Clarified information retrieval about the PMAG in the reactive 1284 mode. 1286 * Removed the extension to the GRE Key Option. 1288 * Clarified the handoff type considerations in Appendix A. 1290 * Home Network Prefix Option, Link-local Address Option and 1291 Vendor-Specific Mobility Option are added. 1293 Changes from -01 to -02 1295 * Aligned HI/HAck message formats with 1296 draft-ietf-mipshop-rfc5268bis-00.txt. 1298 * Revised Section 8 removing the request for the type assignment 1299 of HI/HAck Mobility Headers. 1301 Changes from -02 to -03 1303 * Updated HI/HAck message formats according to 1304 draft-ietf-mipshop-rfc5268bis-01.txt. 1306 * Cleaned up Figure 2 and Figure 3. 1308 * Moved PMIP domain boundary crossing situation in Section 4.1 to 1309 Appendix A.3. 1311 * Removed the alternative protocol operation with an unsolicited 1312 HAck from Section 4.1. 1314 * Modified Code values in the HAck message in order to avoid 1315 collision with those in draft-ietf-mipshop-rfc5268bis-01.txt. 1317 * Clarified the usage scenarios of Context Request Option. 1319 * Modified the description of Code values in the HAck message. 1321 * Changed the container for the IPv4-LMAA from IPv4 Address 1322 option to the LMAA option. 1324 * Made Confidentiality protection "SHOULD" for context transfer. 1326 Changes from -03 to -04 1328 * Added more explanations about MIPv6, FMIPv6 and PMIPv6 in 1329 Abstract. 1331 * Moved Figure 1 to Section 4. 1333 * More clearly indicated the FMIPv6 messages that are not 1334 applicable in the PMIPv6 context. 1336 * Mandated the support of IP Sec on the PMAG and NMAG in order to 1337 protect signaling and user packets and the context information. 1339 * Added a new section for the inter-AR tunneling operation 1340 (Section 4.2). 1342 * Added descriptions about the encapsulation type in Sections 4.1 1343 and 4.3. 1345 * Added a description about buffering requirements on the MAG in 1346 Section 4.1. 1348 * Added a description about the timing of L2 and L3 connection 1349 establishments in Section 4.1. 1351 * Added a new section for PMIPv6-related fast handover issues 1352 (Section 5) and a description about preferable behaviors of the 1353 MN and MAG to reduce packet loss. 1355 * Added Acknowledgments section (Section 9). 1357 * Added a new section for local routing in Appendix (A.2). 1359 Changes from -04 to -05 1361 * Fixed Figure 2 (step (i)). 1363 * Defined the Mobile Network Interface Identifier (MN-IID) 1364 mobility option in Section 6.2.4 (swapped with old Section 1365 6.2.5), and added it to IANA considerations (Section 8). 1367 * Changed from SHOULD to MUST regarding the inclusion of the 1368 MN-ID, MN-HNP, MN-IID and the LMAA options in the HI message 1369 (step (c) in Section 4.1). 1371 * The optional behavior of the NMAG that allows it to send uplink 1372 packets directly to the LMA before the PBU/PBA exchange was 1373 removed from section 4.2 (as out of scope). 1375 * In Section A.3, the description about the HA address assignment 1376 from the NAR to the MN was removed (as out of scope). 1378 Changes from -05 to -06 1380 * Added 'P' flag in the HI and Hack messages to distinguish them 1381 from those in FMIPv6. 1383 * Made editorial corrections in Section 2 (Introduction), Section 1384 3 (Terminology), Section 4 (Protocol Overview) and Section 4.2 1385 (Inter-AR Tunneling Operation). 1387 * Added a description on how forwarded packets should be handled 1388 in the access network at step (f) in Section 4.1. 1390 * Added all types of encapsulation methods that should be 1391 supported in Section 4.1. 1393 * Revised the Code values for the HI message in Section 6.1.1. 1395 * Revised the Code values for the HAck message in Section 6.1.2 1396 and added a description of its usage at step (d) of the 1397 reactive handover mode in Section 4.1. 1399 * Removed the definition of the IP Address Option in Section 1400 6.2.3 and moved to Section 6.2.7, which currently refers to the 1401 IPv4 Home Address Option defined by RFC5555. Revised the IANA 1402 Consideration section accordingly. 1404 * Removed the Option-Code from the Mobile Node Identifier (MN 1405 IID) Option. 1407 * Removed Appendix A.3 (Handling of PMIPv6/MIPv6 switching). 1409 Changes from -06 to -07 1411 * Added explanations about defining and setting the 'P' flag for 1412 the HI and Hack messages in Sections 4 and 4.1. 1414 * Corrected the references for the encapsulation types in Section 1415 4.1. 1417 * Modified the Code values for the HI message in Section 6.1.1 to 1418 avoid overlapping with those in 1419 draft-ietf-mipshop-rfc5268bis-01.txt. 1421 * Modified the reference for the IPv4 Address Option from RFC5555 1422 to [IPv4PMIPv6] in Section 6.2.7. 1424 Changes from -07 to -08 1426 * Corrected the reference for the TLV-header UDP encapsulation in 1427 Section 4.1. 1429 * Updated the version number of the reference document 1430 [IPv4PMIPv6] and the option name defined by that document in 1431 Section 6.2.7. 1433 Changes from -08 to -09 1435 * Added a paragraph at the beginning of Section 4 describing the 1436 assumption related to the lower layer signaling. 1438 * Added a new section on the manageability considerations in 1439 Section 5 describing the configurations on the network and the 1440 mobile node assumed in this document. 1442 * Modified the assumed configuration of the MAG regarding its 1443 link-layer address in Section 5 (Section 5.2 in version -09). 1445 * Specified the requested option to identify the target MN for 1446 the inter-AR tunneling in Section 6.1.1. 1448 * Specified the default context information in the Context 1449 Request Option in Section 6.2.1. 1451 Changes from -09 to -10 1453 * Revised the document based on the comments from TSV-DIR, SEC- 1454 DIR, OPS-DIR and GEN-ART. 1456 + Split the abstract section in half for readability. 1458 + Added the definition of Localized Mobility Anchor (LMA) in 1459 Section 3. 1461 + Added the purpose of this document at the beginning of 1462 Section 4 to make the paragraph more complete. 1464 + Revised the third paragraph of the Security Consideration 1465 section for more precise expression. 1467 + Moved the description about the requirement to set the 'P' 1468 flag in HI/HAck to Sections 6.1.1 and 6.1.2. Also, noted 1469 the 'P' flag setting below the message formats. 1471 + Described the both 'P' and 'F' flags as newly defined ones 1472 in Section 4. 1474 + Clarified the usage of the Context Request Option if a 1475 default set of context information is defined in Section 1476 6.2.1 (changed from "not mandatory" to "not used"). 1478 + Modified the identifier for the interface on the MN to the 1479 MN's link-layer ID (MN LL-ID). 1481 + Corrected the local routing operation of the PMAG in 1482 Appendix A.2. 1484 * Revised the descriptions about the encapsulation mechanism for 1485 the inter-MAG tunnel in Section 4.2 and other related parts for 1486 clarification. 1488 * Also listed the new flags and status codes for the HI/HAck 1489 messages in the IANA Considerations section. 1491 * Elaborated on the example use of the Context Request Option in 1492 Section 6.2.1. 1494 Authors' Addresses 1496 Hidetoshi Yokota 1497 KDDI Lab 1498 2-1-15 Ohara, Fujimino 1499 Saitama, 356-8502 1500 Japan 1502 Email: yokota@kddilabs.jp 1504 Kuntal Chowdhury 1505 Starent Networks 1506 30 International Place 1507 Tewksbury, MA 01876 1508 USA 1510 Email: kchowdhury@starentnetworks.com 1512 Rajeev Koodli 1513 Starent Networks 1514 30 International Place 1515 Tewksbury, MA 01876 1516 USA 1518 Email: rkoodli@starentnetworks.com 1520 Basavaraj Patil 1521 Nokia 1522 6000 Connection Drive 1523 Irving, TX 75039 1524 USA 1526 Email: basavaraj.patil@nokia.com 1528 Frank Xia 1529 Huawei USA 1530 1700 Alma Dr. Suite 500 1531 Plano, TX 75075 1532 USA 1534 Email: xiayangsong@huawei.com