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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group H. Soliman, Ed. 3 Internet-Draft Elevate Technologies 4 Intended status: Standards Track February 27, 2009 5 Expires: August 31, 2009 7 Mobile IPv6 Support for Dual Stack Hosts and Routers 8 draft-ietf-mext-nemo-v4traversal-09.txt 10 Status of this Memo 12 This Internet-Draft is submitted to IETF in full conformance with the 13 provisions of BCP 78 and BCP 79. 15 Internet-Drafts are working documents of the Internet Engineering 16 Task Force (IETF), its areas, and its working groups. Note that 17 other groups may also distribute working documents as Internet- 18 Drafts. 20 Internet-Drafts are draft documents valid for a maximum of six months 21 and may be updated, replaced, or obsoleted by other documents at any 22 time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as "work in progress." 25 The list of current Internet-Drafts can be accessed at 26 http://www.ietf.org/ietf/1id-abstracts.txt. 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 This Internet-Draft will expire on August 31, 2009. 33 Copyright Notice 35 Copyright (c) 2009 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents in effect on the date of 40 publication of this document (http://trustee.ietf.org/license-info). 41 Please review these documents carefully, as they describe your rights 42 and restrictions with respect to this document. 44 Abstract 46 The current Mobile IPv6 and NEMO specifications support IPv6 only. 47 This specification extends those standards to allow the registration 48 of IPv4 addresses and prefixes, respectively, and the transport of 49 both IPv4 and IPv6 packets over the tunnel to the home agent. This 50 specification also allows the Mobile Node to roam over both IPv6 and 51 IPv4, including the case where Network Address Translation is present 52 on the path between the mobile node and its home agent. 54 Table of Contents 56 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 4 57 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 58 2.1. Motivation for Using Mobile IPv6 Only . . . . . . . . . . 6 59 2.2. Scenarios Considered by This Specification . . . . . . . . 6 60 3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 8 61 3.1. Home Agent Address Discovery . . . . . . . . . . . . . . . 8 62 3.2. Mobile Prefix Solicitation and Advertisement . . . . . . . 9 63 3.3. Binding Management . . . . . . . . . . . . . . . . . . . . 9 64 3.3.1. Foreign Network Supports IPv6 . . . . . . . . . . . . 10 65 3.3.2. Foreign Network Supports IPv4 Only . . . . . . . . . . 10 66 3.4. Route Optimization . . . . . . . . . . . . . . . . . . . . 12 67 3.5. Dynamic IPv4 Home Address Allocation . . . . . . . . . . . 13 68 4. Extensions And Modifications To Mobile IPv6 . . . . . . . . . 14 69 4.1. Binding Update Extensions . . . . . . . . . . . . . . . . 14 70 4.1.1. IPv4 Home Address Option . . . . . . . . . . . . . . . 14 71 4.1.2. The IPv4 Care-of Address Option . . . . . . . . . . . 15 72 4.1.3. The Binding Update Message Extensions . . . . . . . . 16 73 4.2. Binding Acknowledgement Extensions . . . . . . . . . . . . 16 74 4.2.1. IPv4 Address Acknowledgement Option . . . . . . . . . 16 75 4.2.2. The NAT Detection Option . . . . . . . . . . . . . . . 18 76 5. Protocol operation . . . . . . . . . . . . . . . . . . . . . . 20 77 5.1. Tunelling Formats . . . . . . . . . . . . . . . . . . . . 20 78 5.1.1. tunnelling Impacts on Transport and MTU . . . . . . . 21 79 5.2. NAT Detection . . . . . . . . . . . . . . . . . . . . . . 21 80 5.3. NAT Keepalives . . . . . . . . . . . . . . . . . . . . . . 23 81 5.4. Mobile Node Operation . . . . . . . . . . . . . . . . . . 24 82 5.4.1. Selecting a Care-of address . . . . . . . . . . . . . 24 83 5.4.2. Sending Binding Updates . . . . . . . . . . . . . . . 25 84 5.4.3. Sending Packets from a Visited Network . . . . . . . . 27 85 5.4.4. Movement Detection in IPv4-only Networks . . . . . . . 28 86 5.5. Home agent operation . . . . . . . . . . . . . . . . . . . 28 87 5.5.1. Sending Packets to the Mobile Node . . . . . . . . . . 30 88 5.6. Correspondent Node Operation . . . . . . . . . . . . . . . 31 89 6. Security Considerations . . . . . . . . . . . . . . . . . . . 32 90 6.1. Handover Interactions for IPsec and IKE . . . . . . . . . 33 91 6.2. IKE negotiation messages between the mobile node and 92 Home Agent . . . . . . . . . . . . . . . . . . . . . . . . 35 93 6.2.1. IKEv2 Operation for Securing DSMIPv6 Signaling . . . . 36 94 6.2.2. IKEv2 Operation for Securing Data over IPv4 . . . . . 39 95 7. Protocol Constants . . . . . . . . . . . . . . . . . . . . . . 41 96 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 42 97 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 43 98 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 44 99 10.1. Normative References . . . . . . . . . . . . . . . . . . . 44 100 10.2. Informative . . . . . . . . . . . . . . . . . . . . . . . 44 101 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 46 102 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 47 104 1. Requirements notation 106 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 107 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 108 document are to be interpreted as described in [RFC2119]. 110 2. Introduction 112 Mobile IPv6 [RFC3775] and [RFC3963] allow mobile nodes to move within 113 the Internet while maintaining reachability and ongoing sessions, 114 using an IPv6 home address or prefix. However, since IPv6 is not 115 widely deployed, it is unlikely that mobile nodes will initially use 116 IPv6 addresses only for their connections. It is reasonable to 117 assume that mobile nodes will, for a long time, need an IPv4 home 118 address that can be used by upper layers. It is also reasonable to 119 assume that mobile nodes will move to networks that might not support 120 IPv6 and would therefore need the capability to support an IPv4 121 Care-of Address. Hence, this specification extends Mobile IPv6 122 capabilities to allow dual stack mobile nodes to request that their 123 home agent (also dual stacked) tunnel IPv4/IPv6 packets addressed to 124 their home addresses, as well as IPv4/IPv6 care-of address(es). 126 Using this specification, mobile nodes would only need Mobile IPv6 127 and [RFC3963] to manage mobility while moving within the Internet; 128 hence eliminating the need to run two mobility management protocols 129 simultaneously. This specification provides the extensions needed in 130 order to allow IPv6 mobility only to be used by dual stack mobile 131 nodes. 133 This specification will also consider cases where a mobile node moves 134 into a private IPv4 network and gets configured with a private IPv4 135 Care-of Address. In these scenarios, the mobile node needs to be 136 able to traverse the IPv4 NAT in order to communicate with the home 137 agent. IPv4 NAT traversal for Mobile IPv6 is presented in this 138 specification. 140 In this specification, the term mobile node refers to both a mobile 141 host and mobile router unless the discussion is specific to either 142 hosts or routers. Similarly, we use the term home address to reflect 143 an address/prefix format. Note that both mobile host and router 144 functionality has already been defined in [RFC3775] and [RFC3963], 145 respectively. This specification does not change that already 146 defined behavior, nor does it extend the specific type of hosts and 147 router support already defined, except for two things: (i) allowing 148 the mobile node to communicate with its home agent even over IPv4 149 networks, and (ii) allowing the use of IPv4 home addresses and 150 prefixes. 152 In this specification, extensions are defined for the binding update 153 and binding acknowledgement. It should be noted that all these 154 extensions apply to cases where the mobile node communicates with a 155 Mobility Anchor Point (MAP) as defined in [RFC5380]. The 156 requirements on the MAP are identical to those stated for the home 157 agent, although it is unlikely that NAT traversal would be needed 158 with a MAP as it is expected to be in the same address domain. 160 2.1. Motivation for Using Mobile IPv6 Only 162 IPv6 offers a number of improvements over today's IPv4, primarily due 163 to its large address space. Mobile IPv6 offers a number of 164 improvements over Mobile IPv4 [RFC3344], mainly due to capabilities 165 inherited from IPv6. For instance, route optimization and dynamic 166 home agent discovery can only be achieved with Mobile IPv6. 168 One of the advantages of the large address space provided by IPv6 is 169 that it allows mobile nodes to obtain a globally unique care-of 170 address wherever they are. Hence, there is no need for Network 171 Address Translator (NAT) traversal techniques designed for Mobile 172 IPv4. This allows Mobile IPv6 to be a significantly simpler and more 173 bandwidth efficient mobility management protocol. At the same time, 174 during the transition towards IPv6, NAT traversal for existing 175 private IPv4 networks needs to be considered. This specification 176 introduces NAT traversal for this purpose. 178 The above benefits make the case for using Mobile IPv6-only for dual 179 stack mobile nodes as it allows for a long lasting mobility solution. 180 The use of Mobile IPv6 for dual stack mobility eliminates the need 181 for changing the mobility solution due to the introduction of IPv6 182 within a deployed network. 184 2.2. Scenarios Considered by This Specification 186 There are several scenarios that illustrate potential 187 incompatibilities for mobile nodes using Mobile IPv6. Some of the 188 problems associated with mobility and transition issues were 189 presented in [RFC4977]. This specification considers the scenarios 190 that address all the problems discussed in [RFC4977]. The scenarios 191 considered in this specification are listed below. 193 All of the following scenarios assume that both the mobile node and 194 the home agent are IPv4 and IPv6-enabled and that only Mobile IPv6 is 195 used between the mobile node and the home agent. We also assume that 196 the home agent is always reachable through a globally unique IPv4 197 address. Finally, it's important to note that the following 198 scenarios are not mutually exclusive. 200 Scenario 1: IPv4-only foreign network 202 In this scenario, a mobile node is connected to an IPv4-only foreign 203 network. The mobile node can only configure an IPv4 Care-of Address. 205 Scenario 2: Mobile node behind a NAT 206 In this scenario, the mobile node is in a private IPv4 foreign 207 network that has a NAT device connecting it to the Internet. If the 208 home agent is located outside the NAT device, the mobile node will 209 need a NAT traversal mechanism to communicate with the home agent. 211 Scenario 3: Home Agent behind a NAT 213 In this scenario, the communication between the mobile node and the 214 home agent is further complicated by the fact that the home agent is 215 located within a private IPv4 network. However, in this scenario, we 216 assume that the home agent is allocated a globally unique IPv4 217 address. The address might not be physically configured on the home 218 agent interface. Instead, it is associated with the home agent on 219 the NAPT device, which allows the home agent to be reachable through 220 address or port mapping. 222 Scenario 4: Use Of IPv4-only applications 224 In this scenario, the mobile node may be located in an IPv4, IPv6 or 225 a dual network. However, the mobile node might be communicating with 226 an IPv4-only node. In this case, the mobile node would need a stable 227 IPv4 address for its application. The alternative to using an IPv4 228 address is the use of protocol translators; however, end-to-end 229 communication with IPv4 is preferred to the use of protocol 230 translators. 232 The mobile node may also be communicating with an IPv4-only 233 application that requires an IPv4 address. 235 The cases above illustrate the need for the allocation of a stable 236 IPv4 home address to the mobile node. This is done using an IPv4 237 home address. Since running Mobile IPv4 and Mobile IPv6 238 simultaneously is problematic (as illustrated in [RFC4977]), this 239 scenario adds a requirement on Mobile IPv6 to support IPv4 home 240 addresses. 242 Scenario 5: IPv6 and IPv4-enabled networks 244 In this scenario, the mobile node should prefer the use of an IPv6 245 care-of address for either its IPv6 or IPv4 home address. Nomral IP 246 in IP tunnelling should be used in this scenario as described in 247 [RFC3775]. Under rare exceptions, where IP in IP tunnelling for IPv6 248 does not allow the mobile node to reach the home agent, the mobile 249 node follows the sending algorithm described in Section 5.4.1. UDP 250 tunnelling in IPv6 networks is proposed in this document as a last 251 resort mechanism when reachability cannot be achieved through normal 252 IP in IP tunnelling. It should not be viewed as a normal mode of 253 operation and should not be used as a first resort. 255 3. Solution Overview 257 In order to allow Mobile IPv6 to be used by dual stack mobile nodes, 258 the following needs to be done: 260 o Mobile nodes should be able to use an IPv4 and IPv6 home or 261 care-of address simultaneously and update their home agents 262 accordingly. 264 o Mobile nodes need to be able to know the IPv4 address of the home 265 agent as well as its IPv6 address. There is no need for IPv4 266 prefix discovery however. 268 o Mobile nodes need to be able to detect the presence of a NAT 269 device and traverse it in order to communicate with the home 270 agent. 272 This section presents an overview of the extensions required in order 273 to allow mobile nodes to use Mobile IPv6 only for IP mobility 274 management 276 3.1. Home Agent Address Discovery 278 Dynamic home agent Address Discovery (DHAAD) was defined in [RFC3775] 279 to allow mobile nodes to discover their home agents by appending a 280 well-known anycast interface identifier to their home link's prefix. 281 However, this mechanism is based on IPv6-anycast routing. If a 282 mobile node is located in an IPv4-only foreign network, it cannot 283 rely on native IPv6 routing. In this scenario, the solution for 284 discovering the home agent's IPv4 address is through the Domain Name 285 System (DNS). If the MN is attached to an IPv6-only or dual stack 286 network, it may also use procedures defined in 287 [I-D.ietf-mip6-bootstrapping-integrated-dhc] to discover home agent 288 information. Note that the use of 289 [I-D.ietf-mip6-bootstrapping-integrated-dhc] cannot give the mobile 290 node information that allows it to communicate with the home agent if 291 the mobile node is located in an IPv4-only network. In this 292 scenario, the mobile node needs to discover the IPv4 address of its 293 home agent through the DNS. 295 For DNS lookup by name, the mobile node should be configured with the 296 name of the home agent. When the mobile node needs to discover a 297 home agent, it sends a DNS request with QNAME set to the configured 298 name. An example is "ha1.example.com". If a home agent has an IPv4 299 and IPv6 address, the corresponding DNS record should be configured 300 with both 'AAAA' and 'A' records. Accordingly, the DNS reply will 301 contain 'AAAA' and 'A' records. 303 For DNS lookup by service, the SRV record defined in [RFC5026] is 304 reused. For instance, if the service name is "mip6" and the protocol 305 name is "ipv6" in the SRV record, the mobile node SHOULD send a DNS 306 request with the QNAME set to "_mip6._ipv6.example.com". The 307 response should contain the home agent's FQDN(s) and may include the 308 corresponding 'AAAA' and 'A' records as well. 310 If multiple home agents reside on the home link, each configured with 311 a public IPv4 address, then the operation above applies. The correct 312 DNS entries can be configured accordingly. 314 3.2. Mobile Prefix Solicitation and Advertisement 316 According to [RFC3775], the mobile node can send a Mobile Prefix 317 Solicitation and receive a Mobile Prefix Advertisement containing all 318 prefixes advertised on the home link. 320 A dual stack mobile node MAY send a Mobile Prefix Solicitation 321 message encapsulated in IPv4 (i.e., IPv6 in IPv4) in the case where 322 the mobile node has no access to IPv6 within the local network. 323 Securing these messages requires the mobile node to have a security 324 association with the home agent, using IPsec and based on the mobile 325 node's IPv4 care-of address as described in [RFC3775], and [RFC4877]. 327 [RFC3775] requires the mobile node to include the home address option 328 in the solicitation message sent to the home agent. If the mobile 329 node is located in an IPv4 network, it will not be assigned an IPv6 330 address to include in the source address. In this case, the mobile 331 node MUST use its home address in the source address field of the 332 IPv6 packet, in addition to using the home address option as expected 333 by [RFC3775]. 335 3.3. Binding Management 337 A dual stack mobile node will need to update its home agent with its 338 care-of address. If a mobile node has an IPv4 and an IPv6 home 339 address, it will need to create a binding cache entry for each 340 address. The format of the IP packet carrying the binding update and 341 acknowledgement messages will vary depending on whether the mobile 342 node has access to IPv6 in the visited network. There are three 343 different scenarios to consider with respect to the visited network: 345 o The visited network has IPv6 connectivity and provides the mobile 346 node with a care-of address (in a stateful or stateless manner). 348 o The mobile node can only configure a globally unique IPv4 address 349 in the visited network. 351 o The mobile node can only configure a private IPv4 address in the 352 visited network. 354 3.3.1. Foreign Network Supports IPv6 356 In this case, the mobile node is able to configure a globally unique 357 IPv6 address. The mobile node will send a binding update to the IPv6 358 address of its home agent, as defined in [RFC3775]. The binding 359 update MAY include the IPv4 home address option introduced in this 360 document. After receiving the binding update, the home agent creates 361 two binding cache entries, one for the mobile node's IPv4 home 362 address, and another for the mobile node's IPv6 home address. Both 363 entries will point to the mobile node's IPv6 care-of address. Hence, 364 whenever a packet is addressed to the mobile node's IPv4 or IPv6 home 365 addresses, the home agent will tunnel it in IPv6 to the mobile node's 366 IPv6 care-of address included in the binding update. Effectively, 367 the mobile node establishes two different tunnels, one for its IPv4 368 traffic (IPv4 in IPv6) and one for its IPv6 traffic (IPv6 in IPv6) 369 with a single binding update. 371 In this scenario, this document extends [RFC3775] by including the 372 IPv4 home address option in the binding update message. Furthermore, 373 if the network supports both IP v4 and IPv6, or if the mobile node is 374 experiencing problems with IP in IP tunnelling, this document 375 proposes some mitigating actions as described in Section 5.4.1 377 After accepting the binding update and creating the corresponding 378 binding cache entries, the home agent MUST send a binding 379 acknowledgement to the mobile node as defined in [RFC3775]. In 380 addition, if the binding update included an IPv4 home address option, 381 the binding acknowledgement MUST include the IPv4 address 382 acknowledgment option as described later in this specification. This 383 option informs the mobile node whether the binding was accepted for 384 the IPv4 home address. If this option is not included in the binding 385 acknowledgement and the IPv4 home address option was included in the 386 binding update, the mobile node MUST assume that the home agent does 387 not support the IPv4 home address option and therefore SHOULD NOT 388 include the option in future binding updates to that home agent 389 address. 391 When a mobile node acquires both IPv4 and IPv6 care-of addresses at 392 the foreign network, it SHOULD prioritize the IPv6 care-of address 393 for its MIPv6 binding as described in Section 5.4.1. 395 3.3.2. Foreign Network Supports IPv4 Only 397 If the mobile node is in a foreign network that only supports IPv4, 398 it needs to detect whether a NAT is in its communication path to the 399 home agent. This is done while exchanging the binding update and 400 acknowledgement messages as shown later in this document. NAT 401 detection is needed for the purposes of the signaling presented in 402 this specification. 404 3.3.2.1. Foreign Network Supports IPv4 Only (Public Addresses) 406 In this scenario the mobile node will need to tunnel IPv6 packets 407 containing the binding update to the home agent's IPv4 address. The 408 mobile node uses the IPv4 address it gets from the foreign network as 409 a source address in the outer header. The binding update will 410 contain the mobile node's IPv6 home address. However, since the 411 care-of address in this scenario is the mobile node's IPv4 address, 412 the mobile node MUST include its IPv4 care-of address in the IPv6 413 packet. The IPv4 address is represented in the IPv4 Care-of address 414 option defined in this specification. If the mobile node had an IPv4 415 home address, it MUST also include the IPv4 home address option 416 described in this specification. 418 After accepting the binding update, the home agent MUST create a new 419 binding cache entry for the mobile node's IPv6 home address. If an 420 IPv4 home address option were included, the home agent MUST create 421 another entry for that address. All entries MUST point to the mobile 422 node's IPv4 care-of address. Hence, all packets addressed to the 423 mobile node's home address(es) (IPv4 or IPv6) will be encapsulated in 424 an IPv4 header that includes the home agent's IPv4 address in the 425 source address field and the mobile node's IPv4 care-of address in 426 the destination address field. 428 After accepting the binding updates and creating the corresponding 429 entries, the home agent MUST send a binding acknowledgement as 430 specified in [RFC3775]. In addition, if the binding update included 431 an IPv4 home address option, the binding acknowledgement MUST include 432 the IPv4 address acknowledgment option as described later in this 433 specification. The binding acknowledgement is encapsulated to the 434 IPv4 care-of address, which was included in the source address field 435 of the IPv4 header encapsulating the binding update. 437 3.3.2.2. Foreign Network Supports IPv4 Only (Private Addresses) 439 In this scenario the mobile node will need to tunnel IPv6 packets 440 containing the binding update to the home agent's IPv4 address. In 441 order to traverse the NAT device, IPv6 packets are tunneled using UDP 442 and IPv4. The UDP port allocated for the home agent is TBD_DSMIPv6. 444 The mobile node uses the IPv4 address it gets from the visited 445 network as a source address in the IPv4 header. The binding update 446 will contain the mobile node's IPv6 home address. 448 After accepting the binding update, the home agent MUST create a new 449 binding cache entry for the mobile node's IPv6 home address. If an 450 IPv4 home address option were included, the home agent MUST create 451 another entry for that address. All entries MUST point to the mobile 452 node's IPv4 care-of address included in the source address of the 453 IPv4 header that encapsulated the binding update message. In 454 addition, the tunnel used MUST indicate UDP encapsulation for NAT 455 traversal. Hence, all packets addressed to the mobile node's home 456 address(es) (IPv4 or IPv6) will be encapsulated in UDP then 457 encapsulated in an IPv4 header that includes the home agent's IPv4 458 address in the source address field and the mobile node's IPv4 care- 459 of address in the destination address field. Note that the home 460 agent MUST store the source UDP port numbers contained in the packet 461 carrying the binding update in order to be able to forward packets to 462 the mobile node. 464 After accepting the binding updates and creating the corresponding 465 entries, the home agent MUST send a binding acknowledgement as 466 specified in [RFC3775]. In addition, if the binding update included 467 an IPv4 home address option, the binding acknowledgement MUST include 468 the IPv4 address acknowledgment option as described later in this 469 specification. The binding acknowledgement is encapsulated in UDP 470 then IPv4 with the home agent's IPv4 address in the source address 471 field and the mobile node's IPv4 care-of address in the destination 472 field. The IPv4 address in the destination field of the IPv4 packet 473 is the source address received in the IPv4 header containing the 474 binding update message. The inner IPv6 packet will contain the home 475 agent's IPv6 address as a source address and the mobile node's IPv6 476 home address in the destination address field. 478 The mobile node needs to maintain the NAT bindings for its current 479 IPv4 care-of address. This is done through sending the binding 480 update regularly to the home agent. 482 3.4. Route Optimization 484 Route optimization, as specified in [RFC3775] will operate in an 485 identical manner for dual stack mobile nodes when they are located in 486 a visited network that provides IPv6 addresses to the mobile node and 487 while communicating with an IPv6-enabled correspondent node. 488 However, when located in an IPv4-only network, or when using the IPv4 489 home address to communicate with an IPv4 correspondent node, route 490 optimization will not be possible due to the difficulty of performing 491 the return routability test. In this specification, UDP 492 encapsulation is only used between the mobile node and its home 493 agent. Therefore, mobile nodes will need to communicate through the 494 home agent. 496 Route optimization will not be possible for IPv4 traffic. That is, 497 traffic addressed to the mobile node's IPv4 home address. This is 498 similar to using Mobile IPv4, therefore there is no reduction of 499 features resulting from using this specification. 501 3.5. Dynamic IPv4 Home Address Allocation 503 It is possible to allow for the mobile node's IPv4 home address to be 504 allocated dynamically. This is done by including 0.0.0.0 in the IPv4 505 home address option included in the binding update. The home agent 506 SHOULD allocate an IPv4 address to the mobile node and include it in 507 the IPv4 address acknowledgement option sent to the mobile node. In 508 this case, the lifetime of the binding is bound to the minimum of the 509 lifetimes of the IPv6 binding and the lease time of the IPv4 home 510 address. 512 4. Extensions And Modifications To Mobile IPv6 514 This section highlights the protocol and implementation additions 515 required to support this specification. 517 4.1. Binding Update Extensions 519 4.1.1. IPv4 Home Address Option 521 This option is included in the Mobility Header including the binding 522 update message sent from the mobile node to a home agent or Mobility 523 Anchor Point. The alignment requirement for this option is 4n. 525 0 1 2 3 526 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 1 527 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 528 | Type | Length |Prefix-len |P| Reserved | 529 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 530 | IPv4 home address | 531 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 533 Figure 1: IPv4 Home Address Option 535 Type 537 TBD 539 Length 541 6 543 Prefix-len 545 The length of the prefix allocated to the mobile node. If only a 546 single address is allocated, this field MUST be set to 32. In the 547 first binding update requesting a prefix, the field contains the 548 prefix length requested. However, in the following binding 549 updates, this field must contain the length of the prefix 550 allocated. A value of zero is invalid and MUST be considered an 551 error. 553 P 555 A flag indicating, when set, that the mobile node requests a 556 mobile network prefix. This flag is only relevant for new 557 requests, and must be ignored for binding refreshes. 559 Reserved 561 This field is reserved for future use. It MUST be set to zero by 562 the sender and ignored by the receiver. 564 IPv4 Home Address 566 The mobile node's IPv4 home address that should be defended by the 567 home agent. This field could contain any unicast IPv4 address 568 (public or private) that was assigned to the mobile node. The 569 value 0.0.0.0 is used to request an IPv4 home address from the 570 home agent. A mobile node may choose to use this option to 571 request a prefix by setting the address to the All Zeroes and 572 setting the P flag. The mobile node could then form an IPv4 home 573 address based on the allocated prefix. Alternatively, the mobile 574 node may use two different options, one for requesting an address 575 (Static or Dynamic) and another for requesting a prefix. 577 4.1.2. The IPv4 Care-of Address Option 579 This option is included in the Mobility Header including the binding 580 update message sent from the mobile node to a home agent or Mobility 581 Anchor Point. The alignment requirement for this option is 4n. 583 0 1 2 3 584 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 1 585 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 586 | Type | Length | Reserved | 587 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 588 | IPv4 Care-of address | 589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 591 Figure 2: The IPv4 CoA Option 593 Type 595 TBD 597 Length 599 6 601 Reserved 603 This field is set to zero by the sender and ignored by the 604 receiver. 606 IPv4 Care-of Address 608 This field contains the mobile node's IPv4 care- of address. The 609 IPv4 care-of address is used when the mobile node is located in an 610 IPv4-only network. 612 4.1.3. The Binding Update Message Extensions 614 This specification extends the Binding Update message with two new 615 flags. The flags are shown and described below. 617 0 1 2 3 618 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 1 619 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 620 | Sequence # | 621 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 |A|H|L|K|M|R|P|F| Reserved | Lifetime | 623 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 625 Figure 3: Binding Update message 627 F 629 When set, this flag indicates a request for forcing UDP 630 encapsulation regardless of whether a NAT is present on the path 631 between the mobile node and the home agent. This flag may be set 632 by the mobile node if it is required to use UDP encapsulation 633 regardless of the presence of a NAT. This flag SHOULD NOT be set 634 when the mobile node is configured with an IPv6 care-of address; 635 with the exception for the scenario mentioned in Section 5.4.1 637 4.2. Binding Acknowledgement Extensions 639 4.2.1. IPv4 Address Acknowledgement Option 641 This option is included in the Mobility Header including the binding 642 acknowledgement message sent from the home agent or Mobility Anchor 643 Point to the mobile node. This option indicates whether a binding 644 cache entry was created for the mobile node's IPv4 address. 645 Additionally, this option includes an IPv4 home address in the case 646 of Dynamic IPv4 home address configuration (i.e., if the unspecified 647 IPv4 address was included in the binding update). The alignment 648 requirement for this option is 4n. 650 0 1 2 3 651 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 1 652 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 653 | Type | Length | Status |Pref-len |Res| 654 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 655 | IPv4 home address | 656 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 658 Figure 4: IPv4 Address Acknowledgement Option 660 Type 662 TBD 664 Length 666 6 668 Status 670 Indicates success or failure for the IPv4 home address binding. 671 Values from 0 to 127 indicate success. Higher values indicate 672 failure. 674 Pref-len 676 The prefix length of the address allocated. This field is only 677 valid in case of success and MUST be set to zero and ignored in 678 case of failure. This field overrides what the mobile node 679 requested (if not equal to the requested length). 681 Res 683 This field is reserved for future use. It MUST be set to zero by 684 the sender and ignored by the receiver 686 IPv4 Home Address 688 The IPv4 home address that the home agent will use in the binding 689 cache entry. This could be a public or private address. This 690 field MUST contain the mobile node's IPv4 home address. If the 691 address were dynamically allocated the home agent will add the 692 address to inform the mobile node. Otherwise, if the address were 693 statically allocated to the mobile node, the home agent will copy 694 it from the binding update message. 696 The following values are allocated for the Status field: 698 o 0 Success 700 o 128 Failure, reason unspecified 702 o 129 Administratively prohibited 704 o 130 Incorrect IPv4 home address 706 o 131 Invalid IPv4 address 708 o 132 Dynamic IPv4 home address assignment not available 710 o 133 Prefix allocation unauthorized 712 4.2.2. The NAT Detection Option 714 This option is sent from the home agent to the mobile node to 715 indicate whether a NAT was in the path. This option MAY also include 716 a suggested NAT binding refresh time for the mobile node. This might 717 be usefl for scenarios where the mobile node is known to be moving 718 within the home agent's administrative domain, and therefore the NAT 719 timeout is known (through configuration) to the home agent. Section 720 3.5 of [RFC5405] discusses issues with NAT timeout in some detail. 722 The alignment requirement for this option is 4n. If a NAT is 723 detected, this option MUST be sent by the home agent. 725 0 1 2 3 726 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 1 727 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 728 | Type | Length |F| Reserved | 729 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 730 | Refresh time | 731 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 733 Figure 5: The NAT Detection Option 735 Type 737 TBD 739 Length 741 6 743 F 744 This flag indicates to the mobile node that UDP encapsulation is 745 required. When set, this flag indicates that the mobile node MUST 746 use UDP encapsulation even if a NAT is not located between the 747 mobile node and home agent. This flag SHOULD NOT be set when the 748 mobile node is assigned an IPv6 care-of address; with the 749 exception for accomodating the scenarios discussed in 750 Section 5.4.1. 752 Reserved 754 This field is reserved for future use. It MUST be set to zero by 755 the sender and ignored by the receiver. 757 Refresh Time 759 A suggested time (in seconds) for the mobile node to refresh the 760 NAT binding. If set to zero, it is ignored. If this field is set 761 to all 1s it means that keepalives are not needed, i.e., no NAT 762 was detected. The home agent MUST be configured with a default 763 value for the refresh time. The recommended value is outlined in 764 Section 7 766 5. Protocol operation 768 This section presents the protocol operation and processing for the 769 messages presented above. In addition, this section introduces the 770 NAT detection and traversal mechanism used by this specification. 772 5.1. Tunelling Formats 774 This specification allows the mobile node to use various tunnelling 775 formats depending on its location and the visited network's 776 capabilities. The mobile node can tunnel IPv6 in IPv4, IPv4 in IPv6 777 or use UDP encapsulation to tunnel IPv6 in IPv4. Naturally, this 778 specification also supports tunnelling IPv6 in IPv6. 780 This specification allows UDP-based tunnelling to be used between the 781 mobile node and its home agent or MAP. A UDP encapsulation format 782 means the following order of headers: 784 IPv4/v6 786 UDP 788 IP (v4 or v6) 790 Other headers 792 Note that the ue of UDP encapsulation for IPv6 care-of addresses 793 SHOULD NOT be done except in the circumstances highlighted in 794 Section 5.4.1. 796 When using this format the receiver would parse the version field 797 following the UDP header in order to determine whether the following 798 header is IPv4 or IPv6. The rest of the headers are processed 799 normally. The above order of headers does not take IPsec headers 800 into account as they may be placed in different parts of the packet. 801 The above format MUST be supported by all implementations of this 802 specification and MUST always be used to send the binding update 803 message. 805 UDP Tunnelling can also encapsulate an ESP header as shown below. 807 IPv4/v6 809 UDP 811 ESP 812 IP (v4 or v6) 814 Other headers 816 The negotiation of the secure tunnel format described above is 817 discussed in Section 6.2. The receiver of a UDP tunnel detects 818 whether an ESP header is present or not based on the UDP port used. 820 5.1.1. tunnelling Impacts on Transport and MTU 822 Changing the tunnel format may occur due to movement of the mobile 823 node from one network to another. This can have impacts on the link 824 and path MTU, which may affect the amount of bandwidth available to 825 the applications. The mobile node may use PMTUD as specified in 826 [RFC4459]. 828 To accommodate traffic that uses Explicit Congestion Notification 829 (ECN), it is RECOMMENDED that the ECN and DSCP information is copied 830 between the inner and outer header as defined in [RFC3168] and 831 [RFC2983]. It is RECOMMENDED that the full-functionality option 832 defined in section 9.1.1 of [RFC3168]is used to deal with ECN. 834 Note that some impementations may not be able to use ECN over the UDP 835 tunnel. This is due to the lack of access to ECN bits in the UDP API 836 on most platforms. However, this issue can be avoided if UDP 837 encapsulation is done in the kernel. 839 Note that when using UDP encapsulation, the TTL field must be 840 decremented in the same manner as when IP in IP encapsulation is 841 used. 843 5.2. NAT Detection 845 This section deals with NAT detection for the purpose of 846 encapsulating packets between the mobile node and the home agent when 847 the mobile node is present in a private IPv4 network. Mobile IPv6 848 uses IKEv2 to establish te IPsec security association between the 849 mobile node and the home agent. IKEv2 has its own NAT detection 850 mechanism. However, IKEv2's NAT detection is only used for the 851 purpose of setting up the IPsec SA for secure traffic. The 852 interactions between the two NAT traversal mechanisms are described 853 in Section 6 855 NAT detection is done when the initial binding update message is sent 856 from the mobile node to the home agent. When located in an IPv4-only 857 foreign link, the mobile node sends the binding update message 858 encapsulated in UDP and IPv4. The source address of the IPv6 packet 859 is the mobile node's IPv6 home address. The destination address is 860 the IPv6 address of the home agent. The IPv4 header contains the 861 IPv4 care-of address in the source address field and the IPv4 address 862 of the home agent in the destination address field. 864 When the home agent receives the encapsulated binding update, it 865 compares the IPv4 address of the source address field in the IPv4 866 header with the IPv4 address included in the IPv4 care-of address 867 option. If the two addresses match, no NAT device was in the path. 868 Otherwise, a NAT was in the path and the NAT detection option is 869 included in the binding acknowledgement. The binding 870 acknowledgement, and all future packets, are then encapsulated in UDP 871 and IPv4. The source address in the IPv4 header is the IPv4 address 872 of the home agent. The destination address is the IPv4 address 873 received in the IPv4 header encapsulating the binding update (this 874 address will be different from the IPv4 care-of address when a NAT is 875 in the path). The source port in the packet is the home agent's 876 source port. The destination port is the source port received in the 877 binding update message. Note that the home agent stores the port 878 numbers and associates them with the mobile node's tunnel in order to 879 forward future packets. 881 Upon receiving the binding acknowledgement with the NAT detection 882 option, the mobile node sets the tunnel to the home agent to UDP 883 encapsulation. Hence, all future packets to the home agent are 884 tunneled in UDP and IPv4. For all tunneled IPv6 packets, the source 885 address in the IPv6 header is the mobile node's IPv6 home address and 886 the destination address is the correspondent node's IPv6 address. 887 All tunneled IPv4 packets will contain the mobile node's IPv4 home 888 address in the source address field of the inner IPv4 packet and the 889 correspondent node's IPv4 address in the destination address field. 890 The outer IPv4 header is the same whether the inner packet is IPv4 or 891 IPv6. 893 If no NAT device was detected in the path between the mobile node and 894 the home agent then IPv6 packets are tunneled in an IPv4 header, 895 unless the home agent forces UDP encapsulation using the F flag. The 896 content of the inner and outer headers are identical to the UDP 897 encapsulation case. 899 A mobile node MUST always tunnel binding updates in UDP when located 900 in an IPv4-only network. Essentially, this process allows for 901 perpetual NAT detection. Similarly, the home agent MUST encapsulate 902 binding acknowledgements in a UDP header whenever the binding update 903 is encapsulated in UDP. 905 In conclusion, the packet formats for the binding update and 906 acknowledgement messages are shown below: 908 Binding update received by the home agent: 910 IPv4 header (src=V4ADDR, dst=HA_V4ADDR) 912 UDP header 914 IPv6 header (src=V6HOA, dst=HAADDR) 916 ESP Header 918 Mobility header 920 BU [IPv4 HAO] 922 IPv4 CoA option 924 Where V4ADDR is either the IPv4 care-of address or the address 925 provided by the NAT device. V6HOA is the IPv6 home address of the 926 mobile node. The binding update MAY also contain the IPv4 home 927 address option IPv4 HAO. 929 Binding acknowledgement sent by the home agent: 931 IPv4 header (src= HA_V4ADDR, dst=V4ADDR) 933 UDP Header 935 IPv6 header (src=HAADDR, dst=V6HOA) 937 ESP Header 939 Mobility Header 941 BA ([IPv4 ACK], NAT DET) 943 Where V6HOA is IPv6 home address of the mobile node. The IPv4 ACK is 944 the IPv4 address acknowledgement option, which is only included if 945 the IPv4 home address option were present in the BU. The NAT DET is 946 the NAT detection option, which MUST be present in the binding 947 acknowledgement message if the binding update was encapsulated in 948 UDP. 950 5.3. NAT Keepalives 952 If a NAT is detected, the mobile node will need to refresh the NAT 953 bindings in order to be reachable from the home agent. NAT bindings 954 can be refreshed through sending and receiving traffic encapsulated 955 in UDP. However, if the mobile node is not active, it will need to 956 periodically send a message to the home agent in order to refresh the 957 NAT binding. This can be done using the binding update message. The 958 binding update/acknowledgement pair will ensure that the NAT bindings 959 are refreshed in a reliable manner. There is no way for the mobile 960 node to know the exact time of the NAT binding. The default time 961 suggested in this specification is NATKATIMEOUT. If the home agent 962 suggests a different refresh period in the binding acknowledgement, 963 the mobile node SHOULD use the value suggested by the home agent. 965 If the refresh time in the NAT detection option in the binding 966 acknowledgement is set to all 1s, the mobile node need not send 967 messages to refresh the NAT binding. However, the mobile node may 968 still be required to encapsulate traffic in UDP. This scenario may 969 take place when a NAT is not detected, but the home agent still 970 requires the mobile node to use UDP encapsulation. 972 It should be noted that a mobile node that does not need to be 973 reachable (i.e., only cares about the session continuity aspect of 974 Mobile IP) it does not need to refresh the NAT binding. In this 975 case, the mobile node would only be able to initiate communication 976 with other nodes. However, this is likely to imply that the mobile 977 node will need to send a binding update before initiating 978 communication after a long idle period as it is likely to be assigned 979 a different port and IPv4 address by the NAT when it initiates 980 communication. Hence, an implementation may choose, for the sake of 981 simplicity, to always maintain the NAT bindings even when it does not 982 need reachability. 984 Note that keepalives are also needed by IKEv2 over UDP port 4500. 985 This is needed for IKE dead peer detection, which is not handled by 986 DSMIPv6 keepalives. 988 5.4. Mobile Node Operation 990 In addition to the operations specified in [RFC3775] and [RFC3963], 991 this specification requires mobile nodes to be able to support an 992 IPv4 home address. This specification also requires the mobile node 993 to choose an IPv4 or an IPv6 care-of address. We first discuss 994 care-of address selection, then continue with binding management and 995 transmission of normal traffic. 997 5.4.1. Selecting a Care-of address 999 When a mobile node is in a dual stacked visited network, it will have 1000 a choice between an IPv4 and an IPv6 care-of address. The mobile 1001 node SHOULD prefer the IPv6 care-of address and bind it to its home 1002 address(es). If a mobile node attempted to bind the IPv6 care-of 1003 address to its home address(es) and the binding update timed out, the 1004 mobile node SHOULD: 1006 o Resend the binding update using the exponential back-off algorithm 1007 described in [RFC3775]. 1009 o If after three attempts in total a binding acknowledgement was not 1010 received, the mobile node SHOULD send a new binding update using 1011 the IPv4 care-of address. The exponential backoff algorithm 1012 described in [RFC3775] should be used for re-transmission of the 1013 binding update if needed. 1015 This procedure should be used to avoid scenarios where IPv6 1016 connectivity may not be as reliable as IPv4. This may take place 1017 during early deployments of IPv6, or simply due to temporary outages 1018 affecting IPv6 routing. 1020 It is RECOMMENDED that upon movement the mobile node does not change 1021 the IP address family chosen for the previous binding update unless 1022 the mobile node is aware that it has moved to a different 1023 administrative domain where previous problems with IPv6 routing may 1024 not be present. Repeating the above procedure upon every movement 1025 can cause significant degradation of the mobile node's applications' 1026 performace due to extended periods of packet losses after handover if 1027 the routing outage is still in effect. 1029 When using an IPv4 care-of address and IP in IP encapsulation, if the 1030 mobile node implementation is made aware by upper layers of 1031 persistent packet losses, it may attempt to resend the binding update 1032 with the F flag set, requesting UDP encapsulation for all packets. 1033 This may avoid packet losses due to situations where local 1034 firewalling policies prevent the use of IP in IP encapsulation. 1036 The effect of these address selection mechanism is to allow the 1037 follwing preferences in the absence of NAT: 1039 1. IPv6 1041 2. IPv4 (using IP in IP or UDP encapsulation if a NAT is detected) 1043 3. UDP encapsulation when IP in IP is not allowed by the local 1044 domain. 1046 5.4.2. Sending Binding Updates 1048 When sending an IPv6 packet containing a binding update while 1049 connected to an IPv4-only access network, mobile nodes MUST ensure 1050 the following: 1052 o The IPv6 packet is encapsulated in UDP. 1054 o The source address in the IPv4 header is the mobile node's IPv4 1055 care-of address. 1057 o The destination address in the IPv4 header is the home agent's 1058 IPv4 address. 1060 o The source address in the IPv6 header is the mobile node's IPv6 1061 home address. 1063 o The IPv4 home address option MAY be included in the mobility 1064 header. This option contains the IPv4 home address. If the 1065 mobile node did not have a static home address it MAY include the 1066 unspecified IPv4 address, which acts as a request for a dynamic 1067 IPv4 home address. Alternatively, one or more IPv4 home address 1068 options may be included with requests for IPv4 prefixes (i.e., 1069 with the P flag set). 1071 o If the mobile node wishes to use UDP encapsulation only, it should 1072 set the F flag in the binding update message. 1074 o The IPv6 packet MUST be authenticated as per [RFC3775], based on 1075 the mobile node's IPv6 home address. 1077 When sending a binding update from a visited network that supports 1078 IPv6, the mobile node MUST follow the rules specified in [RFC3775]. 1079 In addition, if the mobile node has an IPv4 home address or needs 1080 one, it MUST include the IPv4 home address option in the mobility 1081 header. If the mobile node already has a static IPv4 home address, 1082 this address MUST be included in the IPv4 home address option. 1083 Otherwise, if the mobile node needs a dynamic IPv4 address, it MUST 1084 include the IPv4 0.0.0.0 address in the IPv4 home address option. 1086 In addition to the rules in [RFC3775], the mobile node should follow 1087 the care-of address selection guidelines in Section 5.4.1. 1089 When the mobile node receives a binding acknowledgement from the home 1090 agent, it follows the rules in [RFC3775] and [RFC3963]. In addition, 1091 the following actions MUST be made: 1093 o If the status field indicated failure with error code 144, the 1094 mobile node MAY resend the binding update without setting the F 1095 flag. 1097 o If the mobility header includes an IPv4 address acknowledgement 1098 option indicating success, the mobile node should create two 1099 entries in its binding update list, one for the IPv6 home address 1100 and another for the IPv4 home address. 1102 o If the NAT detection option were present, the mobile node MUST 1103 tunnel future packets in UDP and IPv4. This MUST be indicated in 1104 the binding update list. 1106 o If no IPv4 address acknowledgement option were present, and an 1107 IPv4 home address option was present in the binding update, the 1108 mobile node MUST only create one binding update list entry for its 1109 IPv6 home address. The mobile node MAY include the IPv4 home 1110 address option in future binding updates. 1112 o If an IPv4 address acknowledgement option were present and it 1113 indicates failure for the IPv4 home address binding, the mobile 1114 node MUST NOT create an entry for that address in its binding 1115 update list. The mobile node MAY include the IPv4 home address 1116 option in future binding updates. 1118 5.4.2.1. Removing Bindings 1120 Mobile nodes will remove bindings from the home agent's binding cache 1121 whenever they move to the home link, or simply when mobility support 1122 is not needed. 1124 De-registering the IPv6 home address is described in [RFC3775]. The 1125 same mechanism applies in this specification. Mobile nodes may 1126 remove the binding for the IPv4 home address only, by sending a 1127 binding update that does not include the IPv4 home address option. 1128 Upon receiving this binding update, the home agent will replace the 1129 existing cache entries with the content of the new message. This 1130 ensures that the IPv4 home address binding is removed, while 1131 maintining an IPv6 binding. 1133 Note that the mobile node cannot remove the IPv6 home address binding 1134 while maintaining an IPv4 home address binding. 1136 A binding update message with a lifetime of zero, will remove all 1137 bindings for the mobile node. 1139 5.4.3. Sending Packets from a Visited Network 1141 When the mobile node is located in an IPv6-enabled network it sends 1142 and receives IPv6 packets as described in [RFC3775]. In cases where 1143 IP in IP encapsulation is not providing connectivity to the home 1144 agent, the mobile node may choose to encapsulate in UDP as suggested 1145 in Section 5.4.1. However, this encapsulation of IPv6 traffic should 1146 be used as a last resort as described. IPv4 traffic is encapsulated 1147 in IPv6 packets to the home agent. 1149 When the mobile node is located in an IPv4 only network, it will send 1150 IPv6 packets to its home agent according to the following format: 1152 IPv4 header (src=V4CoA, dst=HA_V4ADDR) 1154 [UDP Header] 1156 IPv6 header (src=V6HoA, dst=CN) 1158 Upper Layer protocols 1160 Here the UDP header is only used if a NAT has been detected between 1161 the mobile node and the home agent, or if the home agent forced UDP 1162 encapsulation. V4CoA is the IPv4 care-of address configured by the 1163 mobile node in the visited network. 1165 Similarly, IPv4 packets are sent according to the following format: 1167 IPv4 header (src=V4CoA, dst=HA_V4ADDR) 1169 [UDP Header] 1171 IPv4 header (src=V4HoA, dst=V4CN) 1173 Upper Layer protocols 1175 Here the UDP header is only used if a NAT has been detected between 1176 the mobile node and the home agent, or if the home agent forced UDP 1177 encapsulation. 1179 5.4.4. Movement Detection in IPv4-only Networks 1181 [RFC3775] describes movement detection mostly based on IPv6-specific 1182 triggers and Neighbor Discovery [RFC4861] information. These 1183 triggers are not available in an IPv4-only network. Hence, a mobile 1184 node located in an IPv4-only network SHOULD use [RFC4436] for 1185 guidance on movement detection mechanisms in IPv4-only networks. 1187 The mobile node detects that it's in an IPv4-only network when the 1188 IPv6 movement detection algorithm fails to configure an IPv6 address. 1190 5.5. Home agent operation 1192 In addition to the home agent specification in [RFC3775] and 1193 [RFC3963], the home agent needs to be able to process the IPv4 home 1194 address option and generate the IPv4 address acknowledgement option. 1195 Both options are included in the mobility header. Furthermore, the 1196 home agent MUST be able to detect the presence of a NAT device and 1197 indicate that in the NAT detection option included in the binding 1198 acknowledgement. 1200 A home agent must also act as a proxy for address resolution in IPv4 1201 for the registered IPv4 home addresses of mobile nodes it is serving. 1202 Moreover, the administrative domain of the home agent is responsible 1203 for advertising the routing information of registered IPv4 mobile 1204 network prefixes of the mobile nodes. 1206 In order to comply with this specification, the home agent MUST be 1207 able to find the IPv4 home address of a mobile node when given the 1208 IPv6 home address. That is, given an IPv6 home address, the home 1209 agent MUST store the corresponding IPv4 home address if a static one 1210 is present. If a dynamic address were requested by the mobile node, 1211 the home agent MUST store that address (associated with the IPv6 home 1212 address) after it's allocated to the mobile node. 1214 When the home agent receives a binding update encapsulated in UDP and 1215 containing the IPv4 home address option, it needs to follow all the 1216 steps in [RFC3775] and [RFC3963]. In addition, the following checks 1217 MUST be done: 1219 o If the IPv4 care-of address in the IPv4 CoA option is not the same 1220 as the IPv4 address in the source address in the IPv4 header then 1221 a NAT was in the path. This information should be flagged for the 1222 binding acknowledgement. 1224 o If the F flag in the binding update were set, the home agent needs 1225 to determine whether it accepts forcing UDP encapsulation. If it 1226 does not, the binding acknowledgement is sent with error code 144. 1227 UDP encapsulation SHOULD NOT be used when the mobile node is 1228 located in an IPv6-enabled link, with the exception of the 1229 scenarios outlined in Section 5.4.1. 1231 o If the IPv4 home address option contains a valid unicast IPv4 1232 address, the home agent MUST check that this address is allocated 1233 to the mobile node that has the IPv6 home address included in the 1234 home address option. The same MUST be done for an IPv4 prefix. 1236 o If the IPv4 home address option contained the unspecified IPv4 1237 address, the home agent SHOULD dynamically allocate an IPv4 home 1238 address to the mobile node. If none is available, the home agent 1239 MUST return error code 132 in the status field of the IPv4 address 1240 acknowledgement option. If a prefix were requested, the home 1241 agent SHOULD allocate a prefix with the requested length; if 1242 prefix allocation (of any length) was not possible, the home agent 1243 MUST indicate failure of the operation with the appropriate error 1244 code. 1246 o If the binding update is accepted for the IPv4 home address, the 1247 home agent creates a binding cache entry for the IPv4 home 1248 address/prefix. The home agent MUST include an IPv4 1249 acknowledgement option in the mobility header containing the 1250 binding acknowledgement. 1252 o If the binding update is accepted for both IPv4 and IPv6 home 1253 addresses, the home agent creates separate binding cache entries, 1254 one for each home address. The care-of address is the one 1255 included in the binding update. If the care-of address is an IPv4 1256 address, the home agent MUST setup a tunnel to the IPv4 care-of 1257 address of the mobile node. 1259 When sending a binding acknowledgement to the mobile node, the home 1260 agent constructs the message according to [RFC3775] and [RFC3963]. 1261 Note that the routing header MUST always contain the IPv6 home 1262 address as specified in [RFC3775]. 1264 If the care-of address of the mobile node were an IPv4 address, the 1265 home agent includes the mobile node's IPv6 home address in the 1266 destination address field in the IPv6 header. If a NAT were 1267 detected, the home agent MUST then encapsulate the packet in UDP and 1268 an IPv4 header. The source address is set to the home agent's IPv4 1269 address and the destination address is set to the address received in 1270 the source address of the IPv4 header encapsulating the binding 1271 update. 1273 After creating a binding cache entry for the mobile node's home 1274 addresses, all packets sent to the mobile node's home addresses are 1275 tunneled by the home agent to the mobile node's care-of address. If 1276 a NAT were detected, packets are encapsulated in UDP and IPv4. 1277 Otherwise, if the care-of address is an IPv4 address, and no NAT were 1278 detected, packets are encapsulated in an IPv4 header unless UDP 1279 encapsulation is forced by the home agent. 1281 5.5.1. Sending Packets to the Mobile Node 1283 The home agent follows the rules specified in [RFC3775] for sending 1284 IPv6 packets to mobile nodes located in IPv6 networks. When sending 1285 IPv4 packets to mobile nodes in an IPv6 network, the home agent must 1286 encapsulate the IPv4 packets in IPv6. 1288 When sending IPv6 packets to a mobile node located in an IPv4 1289 network, the home agent must follow the format negotiated in the 1290 binding update/acknowledgement exchange. In the absence of a 1291 negotiated format, the default format that MUST be supported by all 1292 implementations is: 1294 IPv4 header (src= HA_V4ADDR, dst= V4ADDR) 1296 UDP Header 1298 IPv6 header (src=CN, dst= V6HoA) 1300 Upper layer protocols 1302 Where the UDP header is only included if a NAT were detected between 1303 the mobile node and the home agent, or if the home agent forced UDP 1304 encapsulation. V4ADDR is the IPv4 address received in the source 1305 address field of the IPv4 packet containing the binding update. 1307 When sending IPv4 packets to a mobile node located in an IPv4 1308 network, the home agent must follow the format negotiated in the 1309 binding update/acknowledgement exchange. In the absence of a 1310 negotiated format, the default format that MUST be supported by all 1311 implementations is: 1313 IPv4 header (src= HA_V4ADDR, dst= V4ADDR) 1315 [UDP Header] 1317 IPv4 header (src=V4CN, dst= V4HoA) 1319 Upper layer protocols 1321 Where the UDP header is only included if a NAT were detected between 1322 the mobile node and home agent, or if the home agent forced UDP 1323 encapsulation. 1325 5.6. Correspondent Node Operation 1327 This specification has no impact on IPv4 or IPv6 correspondent nodes. 1329 6. Security Considerations 1331 This specification allows a mobile node to send one binding update 1332 for its IPv6 and IPv4 home addresses. This is a slight deviation 1333 from [RFC3775] which requires one binding update per home address. 1334 However, like [RFC3775], the IPsec security association needed to 1335 authenticate the binding update is still based on the mobile node's 1336 IPv6 home address. Therefore, in order to authorize the mobile 1337 node's IPv4 home address binding, the home agent MUST store the IPv4 1338 address corresponding to the IPv6 address that is allocated to a 1339 mobile node. Therefore, it is sufficient for the home agent to know 1340 that the IPsec verification for the packet containing the binding 1341 update was valid provided that it knows which IPv4 home address is 1342 associated with which IPv6 home address. Hence, the security of the 1343 IPv4 home address binding is the same as the IPv6 binding. 1345 In effect, associating the mobile node's IPv4 home address with its 1346 IPv6 home address moves the authorization of the binding update for 1347 the IPv4 address to the Mobile IPv6 implementation, which infers it 1348 from the fact that the mobile node has an IPv6 home address and the 1349 right credentials for sending an authentic binding update for the 1350 IPv6 address. 1352 This specification requires the use of IKEv2 as the default mechanism 1353 for dynamic keying. 1355 In cases where this specification is used for NAT traversal, it is 1356 important to note that it has the same vulnerabilities associated 1357 with [RFC3519]. An attacker is able to hijack the mobile node's 1358 session with the home agent if it can modify the contents of the 1359 outer IPv4 header. The contents of the header are not authenticated 1360 and there is no way for the home agent to verify their validity. 1361 Hence, a man in the middle attack where a change in the contents of 1362 the IPv4 header can cause a legitimate mobile node's traffic to be 1363 diverted to an illegitimate receiver independently of the 1364 authenticity of the binding update message. 1366 In this specification, the binding update message MUST be protected 1367 using ESP transport mode. When the mobile node is located in an 1368 IPv4-only network, the binding update message is encapsulated in UDP 1369 as described earlier. However, UDP SHOULD NOT be used to encapsulate 1370 the binding update message when the mobile node is located in an 1371 IPv6-enabled network. If protection of payload traffic is needed 1372 when the mobile node is located in an IPv4-only network, 1373 encapsulation is done using tunnel mode ESP over port 4500 as 1374 described in [RFC3948]. During the IKE negotiation with the home 1375 agent, if the mobile node and home agent support the use of port 1376 4500, the mobile node MUST establish the security association over 1377 port 4500, regardless of the presence of a NAT. This is done to 1378 avoid the switching between ports 500 and 4500 and the potential 1379 traffic disruption resulting from this switch. 1381 Handovers within private IPv4 networks or from IPv6 to IPv4 networks 1382 will have impacts on the security association between the mobile node 1383 and the home agent. The following section presents the expected 1384 behaviour of the mobile node and home agent in those situations. The 1385 details of the IKE negotiations and messages are illustrated in 1386 Section 6.2 1388 6.1. Handover Interactions for IPsec and IKE 1390 After the mobile node detects movement it configures a new care-of 1391 address. If the mobile node is in an IPv4-only network, it removes 1392 binding update list entries for correspondent nodes since route 1393 optimisation cannot be supported. This may cause inbound packet 1394 losses as remote correspondent nodes are unaware of such movement. 1395 To avoid confusion in the correspondent node, the mobile node SHOULD 1396 deregister its binding with each correspondent node by sending a 1397 deregistration binding update. The deregistration binding update 1398 message is tunnelled to the home agent and onto the correspondent 1399 node. This is done after the mobile node updates the home agent with 1400 its new location as discussed below. 1402 The mobile node sends the binding update message to the home agent. 1403 If the mobile node is in an IPv6-enabled network, the binding update 1404 SHOULD be sent without IPv4/UDP encapsulation, unless UDP 1405 encapsulation is needed as described in Section 5.4.1. If the mobile 1406 node is in an IPv4-only network, then after IPsec processing of the 1407 BU message, it encapsulates the BU in UDP/IPv4 as discussed in 1408 sections 5.2 and 5.4. In order to be able to send the binding update 1409 while in an IPv4-only network, the mobile node needs to use the new 1410 IPv4 care-of address in the outer header, which is different from the 1411 care-of address used in the existing tunnel. This should be done 1412 without permanently updating the tunnel within the mobile node's 1413 implementation in order to allow the mobile node to receive packets 1414 on the old care-of address until the binding acknowledgement is 1415 received. The method used to achieve this effect is implementation 1416 dependent and is outside the scope of this specification. This 1417 implies that the IP forwarding function (which selects the interface 1418 or tunnel through which a packet is sent) is not based solely on the 1419 destination address: some IPv6 packets destined to the home agent are 1420 sent via the existing tunnel, while BUs are sent using the new 1421 care-of address. Since BUs are protected by IPsec, the forwarding 1422 function cannot necessarily determine the correct treatment from the 1423 packet headers. Thus, the DSMIPv6 implementation has to attach 1424 additional information to BUs, and this information has to be 1425 preserved after IPsec processing and made available to the forwarding 1426 function, or additional DSMIP processing added to the forwarding 1427 function. Depending on the mobile node's implementation, meeting 1428 this requirement may require changes to the IPsec implementation. 1430 Upon receiving the binding update message encapsulated in UDP/IPv4, 1431 the home agent processes it as follows. In order to allow the 1432 DSMIPv6 implementation in the home agent to detect the presence of a 1433 NAT on the path to the mobile node, it needs to compare the outer 1434 IPv4 source address with the IPv4 address in the IPv4 care-of address 1435 option. This implies that the information in the outer header will 1436 be preserved after IPsec processing and made available to the DSMIPv6 1437 implementation in the home agent. Depending on the home agent's 1438 implementation, meeting this requirement may require changes to the 1439 IPsec implementation. 1441 The home agent updates its tunnel mode security association to 1442 include the mobile node's care-of address as the remote tunnel header 1443 address, and 4500 as the port number. The IPv4 address and port 1444 number are likely to be wrong; the mobile node provides the correct 1445 information in a separate exchange as described below. When the 1446 mobile node is located in a private IPv4 network (which is detected 1447 as described above), the new address and port number are allocated by 1448 the NAT. The home agent will also enable or disable UDP 1449 encapsulation for outgoing ESP packets for the purpose of NAT 1450 traversal. 1452 If the Key Management Mobility Capability (K) bit was set in the 1453 binding update, and the home agent supports this feature, the home 1454 agent updates its IKE security associations to include the mobile 1455 node's care-of address as the peer address and 4500 as the port 1456 number. The home agent may also need to change NAT traversal fields 1457 in the IKE_SA to enable the dynamic update of the IP address and port 1458 number based on the reception of authenticated IKE messages, or 1459 authenticated packets using tunnel mode ESP. The dynamic updates are 1460 described in section 2.23 of RFC 4306. As described above, when the 1461 mobile node is located in a private IPv4 network, the address and 1462 port number used for IPsec and IKE traffic is not yet known by the 1463 home agent at this point. 1465 The mobile node updates the IKE SA in one of two ways. If the K flag 1466 was set in the binding acknowledgement message, the mobile node 1467 SHOULD send an empty informational message, which results in the IKE 1468 module in the home agent to dynamically update the SA information. 1469 The IKE implementation in the home agent is REQUIRED to support this 1470 feature. Alternatively, the IKE SA should be re-negotiated. Note 1471 that updating the IKE SA MUST take place after the mobile node has 1472 sent the binding update and received the acknowledgement from the 1473 home agent. 1475 It is important to note that the mobile node's IPv4 care-of address 1476 seen by the DSMIPv6 module in the home agent upon receiving the 1477 binding update may differ from the IPv4 care-of address seen by the 1478 IKE module and the care-of address used for forwarding IPsec tunnel 1479 mode traffic. Hence, it is probable that different modules in the 1480 home agent will have a different care-of address that should be used 1481 for encapsulating traffic to the mobile node. 1483 After successfully processing the binding update, the home agent 1484 sends the binding acknowledgement to the mobile node's care-of 1485 address as received in the outer header of the packet containing the 1486 binding update. Note that if the BU was rejected, the BAck is sent 1487 to the same address where the BU was received from. This may require 1488 special treatment in IP forwarding and/or IPsec processing which 1489 resembles sending of BUs in the mobile node (described above). 1491 Upon receiving the binding acknowledgement, the mobile node updates 1492 its local tunnel mode Security Association information to include the 1493 tunnel header IP source address, which is the mobile node's address 1494 and the tunnel header IP destination, which is the home agent's 1495 address. The mobile node may also need to enable or disable UDP 1496 encapsulation for outgoing ESP packets for the purpose of NAT 1497 traversal and the sending of keep alives. 1499 The mobile node MAY use [RFC4555] to update its IKE SA with the home 1500 agent. Using MOBIKE requires negotiating this capability with the 1501 home agent when establishing the SA. In this case, the mobile node 1502 and the home agent MUST NOT update their IPsec SAs locally as this 1503 step is performed by MOBIKE. Furthermore, the use of MOBIKE allows 1504 the mobile node to update the SA independently of the binding update 1505 exchange. Hence, there is no need for the mobile node to wait for a 1506 binding acknowledgement before performing MOBIKE. The use of MOBIKE 1507 is OPTIONAL in this specification. 1509 6.2. IKE negotiation messages between the mobile node and Home Agent 1511 This specification defines a number of possible data encapsulation 1512 formats depending on the mobile node's connectivity to the visited 1513 network. When connected to an IPv6-enabled network, the tunnelling 1514 formats are clear. However, when connected to an IPv4-only network, 1515 care should be taken when negotiating the IKE association and the 1516 consequential tunnelling formats used for secure and insecure 1517 traffic. This section illustrates the IKE message exchange between 1518 the mobile node and home agent when the mobile node is located in an 1519 IPv4-only network. Two different IKE negotiations are considered: 1521 o IKEv2 operation for securing DSMIPv6 Signaling. 1523 o IKEv2 operation for securing Data over IPv4 1525 6.2.1. IKEv2 Operation for Securing DSMIPv6 Signaling 1527 A mobile node connected to an IPv4-only network SHOULD follow the 1528 procedures described below in order to establish an SA for the 1529 protection of binding update and binding acknowledgement messages. 1531 Mobile Node Home Agent 1532 ----------- ---------- 1533 IPv4(source_addr=V4ADDR, dest_addr=HAADDR) 1534 UDP (500, 500) HDR, SAi1, KEi, Ni 1535 NAT-D, NAT-D --> 1537 <- IPv4(source_addr=HAADDR, dest_addr=V4ADDR) 1538 UDP(500,X) HDR, SAr1, KEr, Nr, [CERTREQ] 1539 NAT-D, NAT-D 1541 IPv4(source_addr=V4ADDR, dest_addr=HAADDR) 1542 UDP (4500,4500) HDR, SK 1543 {IDi, [CERT,] [CERTREQ,] [IDr,] AUTH, N(USE_TRANSPORT_MODE), 1544 SAi2, TSi, TSr} 1545 --> 1547 <-- IPv4(source_addr=HAADDR, dest_addr=V4ADDR) 1548 UDP (4500,Y) HDR, SK 1549 {IDr, [CERT,] AUTH, N(USE_TRANSPORT_MODE), 1550 SAr2, TSi, TSr} 1552 The corresponding SPD entries are shown below. 1554 Mobile node SPD-S: 1556 IF local_address = home_address_1 & 1558 remote_address = home_agent_1 & 1560 proto = MH & local_mh_type = BU & remote_mh_type = BAck Then use 1561 SA ESP transport mode 1563 Initiate using IDi = user_1 to address home_agent_1 1565 Home Agent SPD-S: 1567 IF local_address = home_agent_1 & 1569 remote_address = home_address_1 & 1571 proto = MH & local_mh_type = BAck & remote_mh_type = BU Then use 1572 SA ESP transport mode 1574 where home_address_1 is the mobile node's registered IPv6 home 1575 address and home_agent_1 is the IP address of the home agent 1577 The above should result in BU/BA messages with the following BU 1578 received by the home agent. 1580 IPv4 header (src=V4ADDR, dst=HA_V4ADDR) 1582 UDP header (sport=Z, dport=DSMIPv6) 1584 IPv6 header (src=V6HOA, dst=HAADDR) 1586 ESP Header in Transport Mode 1588 Mobility header 1590 BU [IPv4 HAO] 1592 IPv4 CoA option 1594 (+ other as needed) 1596 At the home agent, following UDP de-capsulation, the binding update 1597 is delivered to the IPsec module as shown below: 1599 IPv6 header (src=V6HOA, dst=HAADDR) 1601 ESP Header in Transport Mode 1603 Mobility header 1605 BU [IPv4 HAO] 1607 IPv4 CoA option 1609 (+other as needed) 1611 In addition, V4ADDR and the sport (Z) need to be passed with the 1612 packet to ensure correct processing. 1614 Following IPsec processing, the binding update is delivered to the 1615 DSMIPv6 home agent module as follows: 1617 IPv6 header (src=V6HOA, dst=HAADDR) 1619 Mobility Header 1621 BU [IPv4 HAO] 1623 IPv4 CoA option 1625 (+other as needed) 1627 In addition, V4ADDR and the sport (Z) need to be passed with the 1628 packet to ensure correct processing. 1630 The binding acknowledgement sent by the home agent module to the 1631 IPsec module is as follows: 1633 IPv6 header (src=HAADDR, dst=V6HOA) 1635 Mobility Header 1637 BA ([IPv4 ACK], NAT DET) 1639 (+ other as needed) 1641 In addition, V4ADDR, the sport from the BU (Z), and an indication 1642 that UDP encapsulation must be used, need to be passed with the 1643 packet to ensure correct processing. 1645 The binding acknowledgement sent by the home agent to the mobile node 1646 is as follows: 1648 IPv4 header (src= HA_V4ADDR, dst=V4ADDR) 1650 UDP Header (sport=DSMIPv6, dport=Z) 1652 IPv6 header (src=HAADDR, dst=V6HOA) 1654 ESP Header in Transport Mode 1656 Mobility Header 1658 BA ([IPv4 ACK], NAT DET) 1660 6.2.2. IKEv2 Operation for Securing Data over IPv4 1662 To secure data traffic when the mobile node is located in an IPv4- 1663 only network, the mobile node MUST establish a child_SA for that 1664 purpose. The procedure is as follows: 1666 Mobile Node Home Agent 1667 ----------- ---------- 1668 IPv4(source_addr=V4ADDR, dest_addr=HAADDR) 1669 UDP (4500,4500) < non-ESP Marker > HDR, SK 1670 {[N], SA, Ni, [KEi], TSi, TSr} --> 1672 <--IPv4(source_addr=HAADDR, dest_addr=V4ADDR) 1673 UDP (4500,Y) < non-ESP Marker > HDR, SK 1674 SA, Nr, [KEr], TSi, TSr} 1676 If no NAT is detected, the encapsulation used will be: 1678 IPv4 (source_addr=v4CoA, dest_addr=HAAddr) 1680 ESP 1682 IP (source_addr=HoA, set_addr=CNAddr) 1684 Upper_layer_HDR 1686 where IP=IPv4 or IPv6 and HoA=v4HoA or v6HoA 1688 If a NAT were detected, the encapsulation used will be: 1690 IPv4 (source_addr=v4Addr, dest_addr=HAAddr) 1692 UDP (sport=Y, dport=4500) 1694 ESP 1696 IP (source_addr=HoA, set_addr=CNAddr) 1698 Upper_layer_HDR 1700 Where v4CoA may be the external IPv4 address of the NAT, IP is either 1701 an IPv4 or IPv6 header and HoA is either the IPv4 or the IPv6 HoA. 1702 The above format shows the packet as seen by the home agent. 1704 The SPD, whether a NAT were detected or not, is set as follows. Note 1705 that this rule is designed to match all data from the MN to nodes 1706 other than the home agent. This is done so that this rule does not 1707 overlap with the earlier rule securing BU/BA signaling between the MN 1708 and the HA. 1710 Mobile Node SPD-S: 1712 IF local_address = home_address & 1714 remote_address != home_agent & 1716 proto=any, then use SA ESP tunnel mode 1718 Initiate using IDi = user_1 to address home_agent_1 1720 home agent SPD-S: 1722 IF local_address != home_agent & 1724 remote_address = home_address & 1726 proto=any, then use SA ESP tunnel mode 1728 Where home_address is the MN's registered IPv6 or IPv4 home address 1729 and home_agent is the IPv6 or the IPv4 address of the home agent. 1731 7. Protocol Constants 1733 NATKATIMEOUT 110 seconds 1735 8. Acknowledgements 1737 Thanks to the following members (in alphabetical order) of the MIP6 1738 and NEMO Working Groups for their contributions, discussion, and 1739 review: Jari Arkko, Sri Gundavelli, Wassim Haddad, Conny Larsson, 1740 Acee Lindem, Ahmad Muhanna, Vidya Narayanan, Karen Nielsen and 1741 Keiichi Shima. Thanks to Karen Nielsen, Pasi Eronen and Christian 1742 Kaas-Petersen for raising the issue of IKEv2 interactions and 1743 proposing the solution included in this document. Thanks to Pasi 1744 Eronen for the many thorough reviews of this document. 1746 9. IANA Considerations 1748 The specification requires the following allocations from IANA: 1750 A UDP port is needed for the NAT traversal mechanism described in 1751 section 4.1. 1753 The IPv4 home address option described in section 3.1.1 requires 1754 an option type. This option is included in the Mobility header 1755 described in [RFC3775]. 1757 The IPv4 address acknowledgement option described in section 3.2.1 1758 requires a new option type. This option is included in the 1759 Mobility header described in [RFC3775]. 1761 The NAT detection option described in section 3.2.2 requires a new 1762 option type. This option is included in the Mobility header 1763 described in [RFC3775]. 1765 The IPv4 Care-of address option described in section 3.1.2 1766 requires a new option type allocation [RFC3775]. 1768 The Status field in the IPv4 home address option should be allocated 1769 by IANA under the new registry: "DSMIPv6 IPv4 home address option 1770 status codes". 1772 The status field values are allocated using the following procedure: 1774 1. New Status field values are allocated through IETF review. This 1775 is for all RFC types including standards track, informational, 1776 and experimental status that originate from the IETF and have 1777 been approved by the IESG for publication. 1779 2. Requests for new option type value assignments from outside the 1780 IETF are only made through the publication of an IETF document, 1781 per 1) above. Note also that documents published as "RFC Editor 1782 contributions" [RFC4844] are not considered to be IETF documents. 1784 10. References 1786 10.1. Normative References 1788 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1789 Requirement Levels", BCP 14, RFC 2119, March 1997. 1791 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 1792 IPv6 Specification", RFC 2473, December 1998. 1794 [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support 1795 in IPv6", RFC 3775, June 2004. 1797 [RFC3948] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M. 1798 Stenberg, "UDP Encapsulation of IPsec ESP Packets", 1799 RFC 3948, January 2005. 1801 [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. 1802 Thubert, "Network Mobility (NEMO) Basic Support Protocol", 1803 RFC 3963, January 2005. 1805 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", 1806 RFC 4306, December 2005. 1808 [RFC4436] Aboba, B., Carlson, J., and S. Cheshire, "Detecting 1809 Network Attachment in IPv4 (DNAv4)", RFC 4436, March 2006. 1811 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1812 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1813 September 2007. 1815 [RFC4877] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with 1816 IKEv2 and the Revised IPsec Architecture", RFC 4877, 1817 April 2007. 1819 10.2. Informative 1821 [I-D.ietf-mip6-bootstrapping-integrated-dhc] 1822 Chowdhury, K. and A. Yegin, "MIP6-bootstrapping for the 1823 Integrated Scenario", 1824 draft-ietf-mip6-bootstrapping-integrated-dhc-06 (work in 1825 progress), April 2008. 1827 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 1828 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 1829 March 2000. 1831 [RFC2983] Black, D., "Differentiated Services and Tunnels", 1832 RFC 2983, October 2000. 1834 [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition 1835 of Explicit Congestion Notification (ECN) to IP", 1836 RFC 3168, September 2001. 1838 [RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, 1839 August 2002. 1841 [RFC3519] Levkowetz, H. and S. Vaarala, "Mobile IP Traversal of 1842 Network Address Translation (NAT) Devices", RFC 3519, 1843 April 2003. 1845 [RFC3978] Bradner, S., "IETF Rights in Contributions", RFC 3978, 1846 March 2005. 1848 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 1849 for IPv6 Hosts and Routers", RFC 4213, October 2005. 1851 [RFC4459] Savola, P., "MTU and Fragmentation Issues with In-the- 1852 Network Tunneling", RFC 4459, April 2006. 1854 [RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol 1855 (MOBIKE)", RFC 4555, June 2006. 1857 [RFC4844] Daigle, L. and Internet Architecture Board, "The RFC 1858 Series and RFC Editor", RFC 4844, July 2007. 1860 [RFC4977] Tsirtsis, G. and H. Soliman, "Problem Statement: Dual 1861 Stack Mobility", RFC 4977, August 2007. 1863 [RFC5026] Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6 1864 Bootstrapping in Split Scenario", RFC 5026, October 2007. 1866 [RFC5380] Soliman, H., Castelluccia, C., ElMalki, K., and L. 1867 Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility 1868 Management", RFC 5380, October 2008. 1870 [RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines 1871 for Application Designers", BCP 145, RFC 5405, 1872 November 2008. 1874 Appendix A. Contributors 1876 This document reflects discussions and contributions from several 1877 people including (in alphabetical order): 1879 Vijay Devarapalli: vijay.devarapalli@azairenet.com 1881 James Kempf: kempf@docomolabs-usa.com 1883 Henrik Levkowetz: henrik@levkowetz.com 1885 Pascal Thubert: pthubert@cisco.com 1887 George Tsirtsis: G.Tsirtsis@Qualcomm.com 1889 Wakikawa Ryuji: ryuji@sfc.wide.ad.jp 1891 Author's Address 1893 Hesham Soliman (editor) 1894 Elevate Technologies 1896 Email: hesham@elevatemobile.com