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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 23, 2009 5 Expires: August 27, 2009 7 Mobile IPv6 Support for Dual Stack Hosts and Routers 8 draft-ietf-mext-nemo-v4traversal-08.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 27, 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 40 (http://trustee.ietf.org/license-info) in effect on the date of 41 publication of this document. Please review these documents 42 carefully, as they describe your rights and restrictions with respect 43 to this document. 45 Abstract 47 The current Mobile IPv6 and NEMO specifications support IPv6 only. 48 This specification extends those standards to allow the registration 49 of IPv4 addresses and prefixes, respectively, and the transport of 50 both IPv4 and IPv6 packets over the tunnel to the home agent. This 51 specification also allows the Mobile Node to roam over both IPv6 and 52 IPv4, including the case where Network Address Translation is present 53 on the path between the mobile node and its home agent. 55 Table of Contents 57 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 4 58 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 59 2.1. Motivation for Using Mobile IPv6 Only . . . . . . . . . . 6 60 2.2. Scenarios Considered by This Specification . . . . . . . . 6 61 3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 8 62 3.1. Home Agent Address Discovery . . . . . . . . . . . . . . . 8 63 3.2. Mobile Prefix Solicitation and Advertisement . . . . . . . 9 64 3.3. Binding Management . . . . . . . . . . . . . . . . . . . . 9 65 3.3.1. Foreign Network Supports IPv6 . . . . . . . . . . . . 10 66 3.3.2. Foreign Network Supports IPv4 Only . . . . . . . . . . 10 67 3.4. Route Optimization . . . . . . . . . . . . . . . . . . . . 12 68 3.5. Dynamic IPv4 Home Address Allocation . . . . . . . . . . . 13 69 4. Extensions And Modifications To Mobile IPv6 . . . . . . . . . 14 70 4.1. Binding Update Extensions . . . . . . . . . . . . . . . . 14 71 4.1.1. IPv4 Home Address Option . . . . . . . . . . . . . . . 14 72 4.1.2. The IPv4 Care-of Address Option . . . . . . . . . . . 15 73 4.1.3. The Binding Update Message Extensions . . . . . . . . 16 74 4.2. Binding Acknowledgement Extensions . . . . . . . . . . . . 16 75 4.2.1. IPv4 Address Acknowledgement Option . . . . . . . . . 16 76 4.2.2. The NAT Detection Option . . . . . . . . . . . . . . . 18 77 5. Protocol operation . . . . . . . . . . . . . . . . . . . . . . 20 78 5.1. Tunelling Formats . . . . . . . . . . . . . . . . . . . . 20 79 5.1.1. tunnelling Impacts on Transport and MTU . . . . . . . 21 80 5.2. NAT Detection . . . . . . . . . . . . . . . . . . . . . . 21 81 5.3. NAT Keepalives . . . . . . . . . . . . . . . . . . . . . . 23 82 5.4. Mobile Node Operation . . . . . . . . . . . . . . . . . . 24 83 5.4.1. Selecting a Care-of address . . . . . . . . . . . . . 24 84 5.4.2. Sending Binding Updates . . . . . . . . . . . . . . . 25 85 5.4.3. Sending Packets from a Visited Network . . . . . . . . 27 86 5.4.4. Movement Detection in IPv4-only Networks . . . . . . . 28 87 5.5. Home agent operation . . . . . . . . . . . . . . . . . . . 28 88 5.5.1. Sending Packets to the Mobile Node . . . . . . . . . . 30 89 5.6. Correspondent Node Operation . . . . . . . . . . . . . . . 31 90 6. Security Considerations . . . . . . . . . . . . . . . . . . . 32 91 6.1. Handover Interactions for IPsec and IKE . . . . . . . . . 33 92 6.2. IKE negotiation messages between the mobile node and 93 Home Agent . . . . . . . . . . . . . . . . . . . . . . . . 35 94 6.2.1. IKEv2 Operation for Securing DSMIPv6 Signaling . . . . 36 95 6.2.2. IKEv2 Operation for Securing Data over IPv4 . . . . . 39 96 7. Protocol Constants . . . . . . . . . . . . . . . . . . . . . . 41 97 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 42 98 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 43 99 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 44 100 10.1. Normative References . . . . . . . . . . . . . . . . . . . 44 101 10.2. Informative . . . . . . . . . . . . . . . . . . . . . . . 44 102 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 46 103 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 47 105 1. Requirements notation 107 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 108 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 109 document are to be interpreted as described in [RFC2119]. 111 2. Introduction 113 Mobile IPv6 [RFC3775] and [RFC3963] allow mobile nodes to move within 114 the Internet while maintaining reachability and ongoing sessions, 115 using an IPv6 home address or prefix. However, since IPv6 is not 116 widely deployed, it is unlikely that mobile nodes will initially use 117 IPv6 addresses only for their connections. It is reasonable to 118 assume that mobile nodes will, for a long time, need an IPv4 home 119 address that can be used by upper layers. It is also reasonable to 120 assume that mobile nodes will move to networks that might not support 121 IPv6 and would therefore need the capability to support an IPv4 122 Care-of Address. Hence, this specification extends Mobile IPv6 123 capabilities to allow dual stack mobile nodes to request that their 124 home agent (also dual stacked) tunnel IPv4/IPv6 packets addressed to 125 their home addresses, as well as IPv4/IPv6 care-of address(es). 127 Using this specification, mobile nodes would only need Mobile IPv6 128 and [RFC3963] to manage mobility while moving within the Internet; 129 hence eliminating the need to run two mobility management protocols 130 simultaneously. This specification provides the extensions needed in 131 order to allow IPv6 mobility only to be used by dual stack mobile 132 nodes. 134 This specification will also consider cases where a mobile node moves 135 into a private IPv4 network and gets configured with a private IPv4 136 Care-of Address. In these scenarios, the mobile node needs to be 137 able to traverse the IPv4 NAT in order to communicate with the home 138 agent. IPv4 NAT traversal for Mobile IPv6 is presented in this 139 specification. 141 In this specification, the term mobile node refers to both a mobile 142 host and mobile router unless the discussion is specific to either 143 hosts or routers. Similarly, we use the term home address to reflect 144 an address/prefix format. Note that both mobile host and router 145 functionality has already been defined in [RFC3775] and [RFC3963], 146 respectively. This specification does not change that already 147 defined behavior, nor does it extend the specific type of hosts and 148 router support already defined, except for two things: (i) allowing 149 the mobile node to communicate with its home agent even over IPv4 150 networks, and (ii) allowing the use of IPv4 home addresses and 151 prefixes. 153 In this specification, extensions are defined for the binding update 154 and binding acknowledgement. It should be noted that all these 155 extensions apply to cases where the mobile node communicates with a 156 Mobility Anchor Point (MAP) as defined in [RFC5380]. The 157 requirements on the MAP are identical to those stated for the home 158 agent, although it is unlikely that NAT traversal would be needed 159 with a MAP as it is expected to be in the same address domain. 161 2.1. Motivation for Using Mobile IPv6 Only 163 IPv6 offers a number of improvements over today's IPv4, primarily due 164 to its large address space. Mobile IPv6 offers a number of 165 improvements over Mobile IPv4 [RFC3344], mainly due to capabilities 166 inherited from IPv6. For instance, route optimization and dynamic 167 home agent discovery can only be achieved with Mobile IPv6. 169 One of the advantages of the large address space provided by IPv6 is 170 that it allows mobile nodes to obtain a globally unique care-of 171 address wherever they are. Hence, there is no need for Network 172 Address Translator (NAT) traversal techniques designed for Mobile 173 IPv4. This allows Mobile IPv6 to be a significantly simpler and more 174 bandwidth efficient mobility management protocol. At the same time, 175 during the transition towards IPv6, NAT traversal for existing 176 private IPv4 networks needs to be considered. This specification 177 introduces NAT traversal for this purpose. 179 The above benefits make the case for using Mobile IPv6-only for dual 180 stack mobile nodes as it allows for a long lasting mobility solution. 181 The use of Mobile IPv6 for dual stack mobility eliminates the need 182 for changing the mobility solution due to the introduction of IPv6 183 within a deployed network. 185 2.2. Scenarios Considered by This Specification 187 There are several scenarios that illustrate potential 188 incompatibilities for mobile nodes using Mobile IPv6. Some of the 189 problems associated with mobility and transition issues were 190 presented in [RFC4977]. This specification considers the scenarios 191 that address all the problems discussed in [RFC4977]. The scenarios 192 considered in this specification are listed below. 194 All of the following scenarios assume that both the mobile node and 195 the home agent are IPv4 and IPv6-enabled and that only Mobile IPv6 is 196 used between the mobile node and the home agent. We also assume that 197 the home agent is always reachable through a globally unique IPv4 198 address. Finally, it's important to note that the following 199 scenarios are not mutually exclusive. 201 Scenario 1: IPv4-only foreign network 203 In this scenario, a mobile node is connected to an IPv4-only foreign 204 network. The mobile node can only configure an IPv4 Care-of Address. 206 Scenario 2: Mobile node behind a NAT 207 In this scenario, the mobile node is in a private IPv4 foreign 208 network that has a NAT device connecting it to the Internet. If the 209 home agent is located outside the NAT device, the mobile node will 210 need a NAT traversal mechanism to communicate with the home agent. 212 Scenario 3: Home Agent behind a NAT 214 In this scenario, the communication between the mobile node and the 215 home agent is further complicated by the fact that the home agent is 216 located within a private IPv4 network. However, in this scenario, we 217 assume that the home agent is allocated a globally unique IPv4 218 address. The address might not be physically configured on the home 219 agent interface. Instead, it is associated with the home agent on 220 the NAPT device, which allows the home agent to be reachable through 221 address or port mapping. 223 Scenario 4: Use Of IPv4-only applications 225 In this scenario, the mobile node may be located in an IPv4, IPv6 or 226 a dual network. However, the mobile node might be communicating with 227 an IPv4-only node. In this case, the mobile node would need a stable 228 IPv4 address for its application. The alternative to using an IPv4 229 address is the use of protocol translators; however, end-to-end 230 communication with IPv4 is preferred to the use of protocol 231 translators. 233 The mobile node may also be communicating with an IPv4-only 234 application that requires an IPv4 address. 236 The cases above illustrate the need for the allocation of a stable 237 IPv4 home address to the mobile node. This is done using an IPv4 238 home address. Since running Mobile IPv4 and Mobile IPv6 239 simultaneously is problematic (as illustrated in [RFC4977]), this 240 scenario adds a requirement on Mobile IPv6 to support IPv4 home 241 addresses. 243 Scenario 5: IPv6 and IPv4-enabled networks 245 In this scenario, the mobile node should prefer the use of an IPv6 246 care-of address for either its IPv6 or IPv4 home address. Nomral IP 247 in IP tunnelling should be used in this scenario as described in 248 [RFC3775]. Under rare exceptions, where IP in IP tunnelling for IPv6 249 does not allow the mobile node to reach the home agent, the mobile 250 node follows the sending algorithm described in Section 5.4.1. UDP 251 tunnelling in IPv6 networks is proposed in this document as a last 252 resort mechanism when reachability cannot be achieved through normal 253 IP in IP tunnelling. It should not be viewed as a normal mode of 254 operation and should not be used as a first resort. 256 3. Solution Overview 258 In order to allow Mobile IPv6 to be used by dual stack mobile nodes, 259 the following needs to be done: 261 o Mobile nodes should be able to use an IPv4 and IPv6 home or 262 care-of address simultaneously and update their home agents 263 accordingly. 265 o Mobile nodes need to be able to know the IPv4 address of the home 266 agent as well as its IPv6 address. There is no need for IPv4 267 prefix discovery however. 269 o Mobile nodes need to be able to detect the presence of a NAT 270 device and traverse it in order to communicate with the home 271 agent. 273 This section presents an overview of the extensions required in order 274 to allow mobile nodes to use Mobile IPv6 only for IP mobility 275 management 277 3.1. Home Agent Address Discovery 279 Dynamic home agent Address Discovery (DHAAD) was defined in [RFC3775] 280 to allow mobile nodes to discover their home agents by appending a 281 well-known anycast interface identifier to their home link's prefix. 282 However, this mechanism is based on IPv6-anycast routing. If a 283 mobile node is located in an IPv4-only foreign network, it cannot 284 rely on native IPv6 routing. In this scenario, the solution for 285 discovering the home agent's IPv4 address is through the Domain Name 286 System (DNS). If the MN is attached to an IPv6-only or dual stack 287 network, it may also use procedures defined in 288 [I-D.ietf-mip6-bootstrapping-integrated-dhc] to discover home agent 289 information. Note that the use of 290 [I-D.ietf-mip6-bootstrapping-integrated-dhc] cannot give the mobile 291 node information that allows it to communicate with the home agent if 292 the mobile node is located in an IPv4-only network. In this 293 scenario, the mobile node needs to discover the IPv4 address of its 294 home agent through the DNS. 296 For DNS lookup by name, the mobile node should be configured with the 297 name of the home agent. When the mobile node needs to discover a 298 home agent, it sends a DNS request with QNAME set to the configured 299 name. An example is "ha1.example.com". If a home agent has an IPv4 300 and IPv6 address, the corresponding DNS record should be configured 301 with both 'AAAA' and 'A' records. Accordingly, the DNS reply will 302 contain 'AAAA' and 'A' records. 304 For DNS lookup by service, the SRV record defined in [RFC5026] is 305 reused. For instance, if the service name is "mip6" and the protocol 306 name is "ipv6" in the SRV record, the mobile node SHOULD send a DNS 307 request with the QNAME set to "_mip6._ipv6.example.com". The 308 response should contain the home agent's FQDN(s) and may include the 309 corresponding 'AAAA' and 'A' records as well. 311 If multiple home agents reside on the home link, each configured with 312 a public IPv4 address, then the operation above applies. The correct 313 DNS entries can be configured accordingly. 315 3.2. Mobile Prefix Solicitation and Advertisement 317 According to [RFC3775], the mobile node can send a Mobile Prefix 318 Solicitation and receive a Mobile Prefix Advertisement containing all 319 prefixes advertised on the home link. 321 A dual stack mobile node MAY send a Mobile Prefix Solicitation 322 message encapsulated in IPv4 (i.e., IPv6 in IPv4) in the case where 323 the mobile node has no access to IPv6 within the local network. 324 Securing these messages requires the mobile node to have a security 325 association with the home agent, using IPsec and based on the mobile 326 node's IPv4 care-of address as described in [RFC3775], and [RFC4877]. 328 [RFC3775] requires the mobile node to include the home address option 329 in the solicitation message sent to the home agent. If the mobile 330 node is located in an IPv4 network, it will not be assigned an IPv6 331 address to include in the source address. In this case, the mobile 332 node MUST use its home address in the source address field of the 333 IPv6 packet, in addition to using the home address option as expected 334 by [RFC3775]. 336 3.3. Binding Management 338 A dual stack mobile node will need to update its home agent with its 339 care-of address. If a mobile node has an IPv4 and an IPv6 home 340 address, it will need to create a binding cache entry for each 341 address. The format of the IP packet carrying the binding update and 342 acknowledgement messages will vary depending on whether the mobile 343 node has access to IPv6 in the visited network. There are three 344 different scenarios to consider with respect to the visited network: 346 o The visited network has IPv6 connectivity and provides the mobile 347 node with a care-of address (in a stateful or stateless manner). 349 o The mobile node can only configure a globally unique IPv4 address 350 in the visited network. 352 o The mobile node can only configure a private IPv4 address in the 353 visited network. 355 3.3.1. Foreign Network Supports IPv6 357 In this case, the mobile node is able to configure a globally unique 358 IPv6 address. The mobile node will send a binding update to the IPv6 359 address of its home agent, as defined in [RFC3775]. The binding 360 update MAY include the IPv4 home address option introduced in this 361 document. After receiving the binding update, the home agent creates 362 two binding cache entries, one for the mobile node's IPv4 home 363 address, and another for the mobile node's IPv6 home address. Both 364 entries will point to the mobile node's IPv6 care-of address. Hence, 365 whenever a packet is addressed to the mobile node's IPv4 or IPv6 home 366 addresses, the home agent will tunnel it in IPv6 to the mobile node's 367 IPv6 care-of address included in the binding update. Effectively, 368 the mobile node establishes two different tunnels, one for its IPv4 369 traffic (IPv4 in IPv6) and one for its IPv6 traffic (IPv6 in IPv6) 370 with a single binding update. 372 In this scenario, this document extends [RFC3775] by including the 373 IPv4 home address option in the binding update message. Furthermore, 374 if the network supports both IP v4 and IPv6, or if the mobile node is 375 experiencing problems with IP in IP tunnelling, this document 376 proposes some mitigating actions as described in Section 5.4.1 378 After accepting the binding update and creating the corresponding 379 binding cache entries, the home agent MUST send a binding 380 acknowledgement to the mobile node as defined in [RFC3775]. In 381 addition, if the binding update included an IPv4 home address option, 382 the binding acknowledgement MUST include the IPv4 address 383 acknowledgment option as described later in this specification. This 384 option informs the mobile node whether the binding was accepted for 385 the IPv4 home address. If this option is not included in the binding 386 acknowledgement and the IPv4 home address option was included in the 387 binding update, the mobile node MUST assume that the home agent does 388 not support the IPv4 home address option and therefore SHOULD NOT 389 include the option in future binding updates to that home agent 390 address. 392 When a mobile node acquires both IPv4 and IPv6 care-of addresses at 393 the foreign network, it SHOULD prioritize the IPv6 care-of address 394 for its MIPv6 binding as described in Section 5.4.1. 396 3.3.2. Foreign Network Supports IPv4 Only 398 If the mobile node is in a foreign network that only supports IPv4, 399 it needs to detect whether a NAT is in its communication path to the 400 home agent. This is done while exchanging the binding update and 401 acknowledgement messages as shown later in this document. NAT 402 detection is needed for the purposes of the signaling presented in 403 this specification. 405 3.3.2.1. Foreign Network Supports IPv4 Only (Public Addresses) 407 In this scenario the mobile node will need to tunnel IPv6 packets 408 containing the binding update to the home agent's IPv4 address. The 409 mobile node uses the IPv4 address it gets from the foreign network as 410 a source address in the outer header. The binding update will 411 contain the mobile node's IPv6 home address. However, since the 412 care-of address in this scenario is the mobile node's IPv4 address, 413 the mobile node MUST include its IPv4 care-of address in the IPv6 414 packet. The IPv4 address is represented in the IPv4 Care-of address 415 option defined in this specification. If the mobile node had an IPv4 416 home address, it MUST also include the IPv4 home address option 417 described in this specification. 419 After accepting the binding update, the home agent MUST create a new 420 binding cache entry for the mobile node's IPv6 home address. If an 421 IPv4 home address option were included, the home agent MUST create 422 another entry for that address. All entries MUST point to the mobile 423 node's IPv4 care-of address. Hence, all packets addressed to the 424 mobile node's home address(es) (IPv4 or IPv6) will be encapsulated in 425 an IPv4 header that includes the home agent's IPv4 address in the 426 source address field and the mobile node's IPv4 care-of address in 427 the destination address field. 429 After accepting the binding updates and creating the corresponding 430 entries, the home agent MUST send a binding acknowledgement as 431 specified in [RFC3775]. In addition, if the binding update included 432 an IPv4 home address option, the binding acknowledgement MUST include 433 the IPv4 address acknowledgment option as described later in this 434 specification. The binding acknowledgement is encapsulated to the 435 IPv4 care-of address, which was included in the source address field 436 of the IPv4 header encapsulating the binding update. 438 3.3.2.2. Foreign Network Supports IPv4 Only (Private Addresses) 440 In this scenario the mobile node will need to tunnel IPv6 packets 441 containing the binding update to the home agent's IPv4 address. In 442 order to traverse the NAT device, IPv6 packets are tunneled using UDP 443 and IPv4. The UDP port allocated for the home agent is TBD_DSMIPv6. 445 The mobile node uses the IPv4 address it gets from the visited 446 network as a source address in the IPv4 header. The binding update 447 will contain the mobile node's IPv6 home address. 449 After accepting the binding update, the home agent MUST create a new 450 binding cache entry for the mobile node's IPv6 home address. If an 451 IPv4 home address option were included, the home agent MUST create 452 another entry for that address. All entries MUST point to the mobile 453 node's IPv4 care-of address included in the source address of the 454 IPv4 header that encapsulated the binding update message. In 455 addition, the tunnel used MUST indicate UDP encapsulation for NAT 456 traversal. Hence, all packets addressed to the mobile node's home 457 address(es) (IPv4 or IPv6) will be encapsulated in UDP then 458 encapsulated in an IPv4 header that includes the home agent's IPv4 459 address in the source address field and the mobile node's IPv4 care- 460 of address in the destination address field. Note that the home 461 agent MUST store the source UDP port numbers contained in the packet 462 carrying the binding update in order to be able to forward packets to 463 the mobile node. 465 After accepting the binding updates and creating the corresponding 466 entries, the home agent MUST send a binding acknowledgement as 467 specified in [RFC3775]. In addition, if the binding update included 468 an IPv4 home address option, the binding acknowledgement MUST include 469 the IPv4 address acknowledgment option as described later in this 470 specification. The binding acknowledgement is encapsulated in UDP 471 then IPv4 with the home agent's IPv4 address in the source address 472 field and the mobile node's IPv4 care-of address in the destination 473 field. The IPv4 address in the destination field of the IPv4 packet 474 is the source address received in the IPv4 header containing the 475 binding update message. The inner IPv6 packet will contain the home 476 agent's IPv6 address as a source address and the mobile node's IPv6 477 home address in the destination address field. 479 The mobile node needs to maintain the NAT bindings for its current 480 IPv4 care-of address. This is done through sending the binding 481 update regularly to the home agent. 483 3.4. Route Optimization 485 Route optimization, as specified in [RFC3775] will operate in an 486 identical manner for dual stack mobile nodes when they are located in 487 a visited network that provides IPv6 addresses to the mobile node. 488 However, when located in an IPv4-only network, route optimization 489 will not be possible due to the difficulty of performing the care-of 490 address test. Therefore, mobile nodes will need to communicate 491 through the home agent. 493 Route optimization will not be possible for IPv4 traffic. That is, 494 traffic addressed to the mobile node's IPv4 home address. This is 495 similar to using Mobile IPv4, therefore there is no reduction of 496 features resulting from using this specification. 498 3.5. Dynamic IPv4 Home Address Allocation 500 It is possible to allow for the mobile node's IPv4 home address to be 501 allocated dynamically. This is done by including 0.0.0.0 in the IPv4 502 home address option included in the binding update. The home agent 503 SHOULD allocate an IPv4 address to the mobile node and include it in 504 the IPv4 address acknowledgement option sent to the mobile node. In 505 this case, the lifetime of the binding is bound to the minimum of the 506 lifetimes of the IPv6 binding and the lease time of the IPv4 home 507 address. 509 4. Extensions And Modifications To Mobile IPv6 511 This section highlights the protocol and implementation additions 512 required to support this specification. 514 4.1. Binding Update Extensions 516 4.1.1. IPv4 Home Address Option 518 This option is included in the Mobility Header including the binding 519 update message sent from the mobile node to a home agent or Mobility 520 Anchor Point. The alignment requirement for this option is 4n. 522 0 1 2 3 523 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 1 524 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 525 | Type | Length |Prefix-len |P| Reserved | 526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 527 | IPv4 home address | 528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 530 Figure 1: IPv4 Home Address Option 532 Type 534 TBD 536 Length 538 6 540 Prefix-len 542 The length of the prefix allocated to the mobile node. If only a 543 single address is allocated, this field MUST be set to 32. In the 544 first binding update requesting a prefix, the field contains the 545 prefix length requested. However, in the following binding 546 updates, this field must contain the length of the prefix 547 allocated. A value of zero is invalid and MUST be considered an 548 error. 550 P 552 A flag indicating, when set, that the mobile node requests a 553 mobile network prefix. This flag is only relevant for new 554 requests, and must be ignored for binding refreshes. 556 Reserved 558 This field is reserved for future use. It MUST be set to zero by 559 the sender and ignored by the receiver. 561 IPv4 Home Address 563 The mobile node's IPv4 home address that should be defended by the 564 home agent. This field could contain any unicast IPv4 address 565 (public or private) that was assigned to the mobile node. The 566 value 0.0.0.0 is used to request an IPv4 home address from the 567 home agent. A mobile node may choose to use this option to 568 request a prefix by setting the address to the All Zeroes and 569 setting the P flag. The mobile node could then form an IPv4 home 570 address based on the allocated prefix. Alternatively, the mobile 571 node may use two different options, one for requesting an address 572 (Static or Dynamic) and another for requesting a prefix. 574 4.1.2. The IPv4 Care-of Address Option 576 This option is included in the Mobility Header including the binding 577 update message sent from the mobile node to a home agent or Mobility 578 Anchor Point. The alignment requirement for this option is 4n. 580 0 1 2 3 581 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 1 582 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 583 | Type | Length | Reserved | 584 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 585 | IPv4 Care-of address | 586 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 588 Figure 2: The IPv4 CoA Option 590 Type 592 TBD 594 Length 596 6 598 Reserved 600 This field is set to zero by the sender and ignored by the 601 receiver. 603 IPv4 Care-of Address 605 This field contains the mobile node's IPv4 care- of address. The 606 IPv4 care-of address is used when the mobile node is located in an 607 IPv4-only network. 609 4.1.3. The Binding Update Message Extensions 611 This specification extends the Binding Update message with two new 612 flags. The flags are shown and described below. 614 0 1 2 3 615 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 1 616 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 617 | Sequence # | 618 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 619 |A|H|L|K|M|R|P|F| Reserved | Lifetime | 620 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 Figure 3: Binding Update message 624 F 626 When set, this flag indicates a request for forcing UDP 627 encapsulation regardless of whether a NAT is present on the path 628 between the mobile node and the home agent. This flag may be set 629 by the mobile node if it is required to use UDP encapsulation 630 regardless of the presence of a NAT. This flag SHOULD NOT be set 631 when the mobile node is configured with an IPv6 care-of address; 632 with the exception for the scenario mentioned in Section 5.4.1 634 4.2. Binding Acknowledgement Extensions 636 4.2.1. IPv4 Address Acknowledgement Option 638 This option is included in the Mobility Header including the binding 639 acknowledgement message sent from the home agent or Mobility Anchor 640 Point to the mobile node. This option indicates whether a binding 641 cache entry was created for the mobile node's IPv4 address. 642 Additionally, this option includes an IPv4 home address in the case 643 of Dynamic IPv4 home address configuration (i.e., if the unspecified 644 IPv4 address was included in the binding update). The alignment 645 requirement for this option is 4n. 647 0 1 2 3 648 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 1 649 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 650 | Type | Length | Status |Pref-len |Res| 651 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 652 | IPv4 home address | 653 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 655 Figure 4: IPv4 Address Acknowledgement Option 657 Type 659 TBD 661 Length 663 6 665 Status 667 Indicates success or failure for the IPv4 home address binding. 668 Values from 0 to 127 indicate success. Higher values indicate 669 failure. 671 Pref-len 673 The prefix length of the address allocated. This field is only 674 valid in case of success and MUST be set to zero and ignored in 675 case of failure. This field overrides what the mobile node 676 requested (if not equal to the requested length). 678 Res 680 This field is reserved for future use. It MUST be set to zero by 681 the sender and ignored by the receiver 683 IPv4 Home Address 685 The IPv4 home address that the home agent will use in the binding 686 cache entry. This could be a public or private address. This 687 field MUST contain the mobile node's IPv4 home address. If the 688 address were dynamically allocated the home agent will add the 689 address to inform the mobile node. Otherwise, if the address were 690 statically allocated to the mobile node, the home agent will copy 691 it from the binding update message. 693 The following values are allocated for the Status field: 695 o 0 Success 697 o 128 Failure, reason unspecified 699 o 129 Administratively prohibited 701 o 130 Incorrect IPv4 home address 703 o 131 Invalid IPv4 address 705 o 132 Dynamic IPv4 home address assignment not available 707 o 133 Prefix allocation unauthorized 709 4.2.2. The NAT Detection Option 711 This option is sent from the home agent to the mobile node to 712 indicate whether a NAT was in the path. This option MAY also include 713 a suggested NAT binding refresh time for the mobile node. This might 714 be usefl for scenarios where the mobile node is known to be moving 715 within the home agent's administrative domain, and therefore the NAT 716 timeout is known (through configuration) to the home agent. Section 717 3.5 of [RFC5405] discusses issues with NAT timeout in some detail. 719 The alignment requirement for this option is 4n. If a NAT is 720 detected, this option MUST be sent by the home agent. 722 0 1 2 3 723 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 1 724 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 725 | Type | Length |F| Reserved | 726 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 727 | Refresh time | 728 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 730 Figure 5: The NAT Detection Option 732 Type 734 TBD 736 Length 738 6 740 F 741 This flag indicates to the mobile node that UDP encapsulation is 742 required. When set, this flag indicates that the mobile node MUST 743 use UDP encapsulation even if a NAT is not located between the 744 mobile node and home agent. This flag SHOULD NOT be set when the 745 mobile node is assigned an IPv6 care-of address; with the 746 exception for accomodating the scenarios discussed in 747 Section 5.4.1. 749 Reserved 751 This field is reserved for future use. It MUST be set to zero by 752 the sender and ignored by the receiver. 754 Refresh Time 756 A suggested time (in seconds) for the mobile node to refresh the 757 NAT binding. If set to zero, it is ignored. If this field is set 758 to all 1s it means that keepalives are not needed, i.e., no NAT 759 was detected. The home agent MUST be configured with a default 760 value for the refresh time. The recommended value is outlined in 761 Section 7 763 5. Protocol operation 765 This section presents the protocol operation and processing for the 766 messages presented above. In addition, this section introduces the 767 NAT detection and traversal mechanism used by this specification. 769 5.1. Tunelling Formats 771 This specification allows the mobile node to use various tunnelling 772 formats depending on its location and the visited network's 773 capabilities. The mobile node can tunnel IPv6 in IPv4, IPv4 in IPv6 774 or use UDP encapsulation to tunnel IPv6 in IPv4. Naturally, this 775 specification also supports tunnelling IPv6 in IPv6. 777 This specification allows UDP-based tunnelling to be used between the 778 mobile node and its home agent or MAP. A UDP encapsulation format 779 means the following order of headers: 781 IPv4/v6 783 UDP 785 IP (v4 or v6) 787 Other headers 789 Note that the ue of UDP encapsulation for IPv6 care-of addresses 790 SHOULD NOT be done except in the circumstances highlighted in 791 Section 5.4.1. 793 When using this format the receiver would parse the version field 794 following the UDP header in order to determine whether the following 795 header is IPv4 or IPv6. The rest of the headers are processed 796 normally. The above order of headers does not take IPsec headers 797 into account as they may be placed in different parts of the packet. 798 The above format MUST be supported by all implementations of this 799 specification and MUST always be used to send the binding update 800 message. 802 UDP Tunnelling can also encapsulate an ESP header as shown below. 804 IPv4/v6 806 UDP 808 ESP 809 IP (v4 or v6) 811 Other headers 813 The negotiation of the secure tunnel format described above is 814 discussed in Section 6.2. The receiver of a UDP tunnel detects 815 whether an ESP header is present or not based on the UDP port used. 817 5.1.1. tunnelling Impacts on Transport and MTU 819 Changing the tunnel format may occur due to movement of the mobile 820 node from one network to another. This can have impacts on the link 821 and path MTU, which may affect the amount of bandwidth available to 822 the applications. The mobile node may use PMTUD as specified in 823 [RFC4459]. 825 To accommodate traffic that uses Explicit Congestion Notification 826 (ECN), it is RECOMMENDED that the ECN and DSCP information is copied 827 between the inner and outer header as defined in [RFC3168] and 828 [RFC2983]. It is RECOMMENDED that the full-functionality option 829 defined in section 9.1.1 of [RFC3168]is used to deal with ECN. 831 Note that some impementations may not be able to use ECN over the UDP 832 tunnel. This is due to the lack of access to ECN bits in the UDP API 833 on most platforms. However, this issue can be avoided if UDP 834 encapsulation is done in the kernel. 836 Note that when using UDP encapsulation, the TTL field must be 837 decremented in the same manner as when IP in IP encapsulation is 838 used. 840 5.2. NAT Detection 842 This section deals with NAT detection for the purpose of 843 encapsulating packets between the mobile node and the home agent when 844 the mobile node is present in a private IPv4 network. Mobile IPv6 845 uses IKEv2 to establish te IPsec security association between the 846 mobile node and the home agent. IKEv2 has its own NAT detection 847 mechanism. However, IKEv2's NAT detection is only used for the 848 purpose of setting up the IPsec SA for secure traffic. The 849 interactions between the two NAT traversal mechanisms are described 850 in Section 6 852 NAT detection is done when the initial binding update message is sent 853 from the mobile node to the home agent. When located in an IPv4-only 854 foreign link, the mobile node sends the binding update message 855 encapsulated in UDP and IPv4. The source address of the IPv6 packet 856 is the mobile node's IPv6 home address. The destination address is 857 the IPv6 address of the home agent. The IPv4 header contains the 858 IPv4 care-of address in the source address field and the IPv4 address 859 of the home agent in the destination address field. 861 When the home agent receives the encapsulated binding update, it 862 compares the IPv4 address of the source address field in the IPv4 863 header with the IPv4 address included in the IPv4 care-of address 864 option. If the two addresses match, no NAT device was in the path. 865 Otherwise, a NAT was in the path and the NAT detection option is 866 included in the binding acknowledgement. The binding 867 acknowledgement, and all future packets, are then encapsulated in UDP 868 and IPv4. The source address in the IPv4 header is the IPv4 address 869 of the home agent. The destination address is the IPv4 address 870 received in the IPv4 header encapsulating the binding update (this 871 address will be different from the IPv4 care-of address when a NAT is 872 in the path). The source port in the packet is the home agent's 873 source port. The destination port is the source port received in the 874 binding update message. Note that the home agent stores the port 875 numbers and associates them with the mobile node's tunnel in order to 876 forward future packets. 878 Upon receiving the binding acknowledgement with the NAT detection 879 option, the mobile node sets the tunnel to the home agent to UDP 880 encapsulation. Hence, all future packets to the home agent are 881 tunneled in UDP and IPv4. For all tunneled IPv6 packets, the source 882 address in the IPv6 header is the mobile node's IPv6 home address and 883 the destination address is the correspondent node's IPv6 address. 884 All tunneled IPv4 packets will contain the mobile node's IPv4 home 885 address in the source address field of the inner IPv4 packet and the 886 correspondent node's IPv4 address in the destination address field. 887 The outer IPv4 header is the same whether the inner packet is IPv4 or 888 IPv6. 890 If no NAT device was detected in the path between the mobile node and 891 the home agent then IPv6 packets are tunneled in an IPv4 header, 892 unless the home agent forces UDP encapsulation using the F flag. The 893 content of the inner and outer headers are identical to the UDP 894 encapsulation case. 896 A mobile node MUST always tunnel binding updates in UDP when located 897 in an IPv4-only network. Essentially, this process allows for 898 perpetual NAT detection. Similarly, the home agent MUST encapsulate 899 binding acknowledgements in a UDP header whenever the binding update 900 is encapsulated in UDP. 902 In conclusion, the packet formats for the binding update and 903 acknowledgement messages are shown below: 905 Binding update received by the home agent: 907 IPv4 header (src=V4ADDR, dst=HA_V4ADDR) 909 UDP header 911 IPv6 header (src=V6HOA, dst=HAADDR) 913 ESP Header 915 Mobility header 917 BU [IPv4 HAO] 919 IPv4 CoA option 921 Where V4ADDR is either the IPv4 care-of address or the address 922 provided by the NAT device. V6HOA is the IPv6 home address of the 923 mobile node. The binding update MAY also contain the IPv4 home 924 address option IPv4 HAO. 926 Binding acknowledgement sent by the home agent: 928 IPv4 header (src= HA_V4ADDR, dst=V4ADDR) 930 UDP Header 932 IPv6 header (src=HAADDR, dst=V6HOA) 934 ESP Header 936 Mobility Header 938 BA ([IPv4 ACK], NAT DET) 940 Where V6HOA is IPv6 home address of the mobile node. The IPv4 ACK is 941 the IPv4 address acknowledgement option, which is only included if 942 the IPv4 home address option were present in the BU. The NAT DET is 943 the NAT detection option, which MUST be present in the binding 944 acknowledgement message if the binding update was encapsulated in 945 UDP. 947 5.3. NAT Keepalives 949 If a NAT is detected, the mobile node will need to refresh the NAT 950 bindings in order to be reachable from the home agent. NAT bindings 951 can be refreshed through sending and receiving traffic encapsulated 952 in UDP. However, if the mobile node is not active, it will need to 953 periodically send a message to the home agent in order to refresh the 954 NAT binding. This can be done using the binding update message. The 955 binding update/acknowledgement pair will ensure that the NAT bindings 956 are refreshed in a reliable manner. There is no way for the mobile 957 node to know the exact time of the NAT binding. The default time 958 suggested in this specification is NATKATIMEOUT. If the home agent 959 suggests a different refresh period in the binding acknowledgement, 960 the mobile node SHOULD use the value suggested by the home agent. 962 If the refresh time in the NAT detection option in the binding 963 acknowledgement is set to all 1s, the mobile node need not send 964 messages to refresh the NAT binding. However, the mobile node may 965 still be required to encapsulate traffic in UDP. This scenario may 966 take place when a NAT is not detected, but the home agent still 967 requires the mobile node to use UDP encapsulation. 969 It should be noted that a mobile node that does not need to be 970 reachable (i.e., only cares about the session continuity aspect of 971 Mobile IP) it does not need to refresh the NAT binding. In this 972 case, the mobile node would only be able to initiate communication 973 with other nodes. However, this is likely to imply that the mobile 974 node will need to send a binding update before initiating 975 communication after a long idle period as it is likely to be assigned 976 a different port and IPv4 address by the NAT when it initiates 977 communication. Hence, an implementation may choose, for the sake of 978 simplicity, to always maintain the NAT bindings even when it does not 979 need reachability. 981 Note that keepalives are also needed by IKEv2 over UDP port 4500. 982 This is needed for IKE dead peer detection, which is not handled by 983 DSMIPv6 keepalives. 985 5.4. Mobile Node Operation 987 In addition to the operations specified in [RFC3775] and [RFC3963], 988 this specification requires mobile nodes to be able to support an 989 IPv4 home address. This specification also requires the mobile node 990 to choose an IPv4 or an IPv6 care-of address. We first discuss 991 care-of address selection, then continue with binding management and 992 transmission of normal traffic. 994 5.4.1. Selecting a Care-of address 996 When a mobile node is in a dual stacked visited network, it will have 997 a choice between an IPv4 and an IPv6 care-of address. The mobile 998 node SHOULD prefer the IPv6 care-of address and bind it to its home 999 address(es). If a mobile node attempted to bind the IPv6 care-of 1000 address to its home address(es) and the binding update timed out, the 1001 mobile node SHOULD: 1003 o Resend the binding update using the exponential back-off algorithm 1004 described in [RFC3775]. 1006 o If after three attempts in total a binding acknowledgement was not 1007 received, the mobile node SHOULD send a new binding update using 1008 the IPv4 care-of address. The exponential backoff algorithm 1009 described in [RFC3775] should be used for re-transmission of the 1010 binding update if needed. 1012 This procedure should be used to avoid scenarios where IPv6 1013 connectivity may not be as reliable as IPv4. This may take place 1014 during early deployments of IPv6, or simply due to temporary outages 1015 affecting IPv6 routing. 1017 It is RECOMMENDED that upon movement the mobile node does not change 1018 the IP address family chosen for the previous binding update unless 1019 the mobile node is aware that it has moved to a different 1020 administrative domain where previous problems with IPv6 routing may 1021 not be present. Repeating the above procedure upon every movement 1022 can cause significant degradation of the mobile node's applications' 1023 performace due to extended periods of packet losses after handover if 1024 the routing outage is still in effect. 1026 When using an IPv4 care-of address and IP in IP encapsulation, if the 1027 mobile node implementation is made aware by upper layers of 1028 persistent packet losses, it may attempt to resend the binding update 1029 with the F flag set, requesting UDP encapsulation for all packets. 1030 This may avoid packet losses due to situations where local 1031 firewalling policies prevent the use of IP in IP encapsulation. 1033 The effect of these address selection mechanism is to allow the 1034 follwing preferences in the absence of NAT: 1036 1. IPv6 1038 2. IPv4 (using IP in IP or UDP encapsulation if a NAT is detected) 1040 3. UDP encapsulation when IP in IP is not allowed by the local 1041 domain. 1043 5.4.2. Sending Binding Updates 1045 When sending an IPv6 packet containing a binding update while 1046 connected to an IPv4-only access network, mobile nodes MUST ensure 1047 the following: 1049 o The IPv6 packet is encapsulated in UDP. 1051 o The source address in the IPv4 header is the mobile node's IPv4 1052 care-of address. 1054 o The destination address in the IPv4 header is the home agent's 1055 IPv4 address. 1057 o The source address in the IPv6 header is the mobile node's IPv6 1058 home address. 1060 o The IPv4 home address option MAY be included in the mobility 1061 header. This option contains the IPv4 home address. If the 1062 mobile node did not have a static home address it MAY include the 1063 unspecified IPv4 address, which acts as a request for a dynamic 1064 IPv4 home address. Alternatively, one or more IPv4 home address 1065 options may be included with requests for IPv4 prefixes (i.e., 1066 with the P flag set). 1068 o If the mobile node wishes to use UDP encapsulation only, it should 1069 set the F flag in the binding update message. 1071 o The IPv6 packet MUST be authenticated as per [RFC3775], based on 1072 the mobile node's IPv6 home address. 1074 When sending a binding update from a visited network that supports 1075 IPv6, the mobile node MUST follow the rules specified in [RFC3775]. 1076 In addition, if the mobile node has an IPv4 home address or needs 1077 one, it MUST include the IPv4 home address option in the mobility 1078 header. If the mobile node already has a static IPv4 home address, 1079 this address MUST be included in the IPv4 home address option. 1080 Otherwise, if the mobile node needs a dynamic IPv4 address, it MUST 1081 include the IPv4 0.0.0.0 address in the IPv4 home address option. 1083 In addition to the rules in [RFC3775], the mobile node should follow 1084 the care-of address selection guidelines in Section 5.4.1. 1086 When the mobile node receives a binding acknowledgement from the home 1087 agent, it follows the rules in [RFC3775] and [RFC3963]. In addition, 1088 the following actions MUST be made: 1090 o If the status field indicated failure with error code 144, the 1091 mobile node MAY resend the binding update without setting the F 1092 flag. 1094 o If the mobility header includes an IPv4 address acknowledgement 1095 option indicating success, the mobile node should create two 1096 entries in its binding update list, one for the IPv6 home address 1097 and another for the IPv4 home address. 1099 o If the NAT detection option were present, the mobile node MUST 1100 tunnel future packets in UDP and IPv4. This MUST be indicated in 1101 the binding update list. 1103 o If no IPv4 address acknowledgement option were present, and an 1104 IPv4 home address option was present in the binding update, the 1105 mobile node MUST only create one binding update list entry for its 1106 IPv6 home address. The mobile node MAY include the IPv4 home 1107 address option in future binding updates. 1109 o If an IPv4 address acknowledgement option were present and it 1110 indicates failure for the IPv4 home address binding, the mobile 1111 node MUST NOT create an entry for that address in its binding 1112 update list. The mobile node MAY include the IPv4 home address 1113 option in future binding updates. 1115 5.4.2.1. Removing Bindings 1117 Mobile nodes will remove bindings from the home agent's binding cache 1118 whenever they move to the home link, or simply when mobility support 1119 is not needed. 1121 De-registering the IPv6 home address is described in [RFC3775]. The 1122 same mechanism applies in this specification. Mobile nodes may 1123 remove the binding for the IPv4 home address only, by sending a 1124 binding update that does not include the IPv4 home address option. 1125 Upon receiving this binding update, the home agent will replace the 1126 existing cache entries with the content of the new message. This 1127 ensures that the IPv4 home address binding is removed, while 1128 maintining an IPv6 binding. 1130 Note that the mobile node cannot remove the IPv6 home address binding 1131 while maintaining an IPv4 home address binding. 1133 A binding update message with a lifetime of zero, will remove all 1134 bindings for the mobile node. 1136 5.4.3. Sending Packets from a Visited Network 1138 When the mobile node is located in an IPv6-enabled network it sends 1139 and receives IPv6 packets as described in [RFC3775]. In cases where 1140 IP in IP encapsulation is not providing connectivity to the home 1141 agent, the mobile node may choose to encapsulate in UDP as suggested 1142 in Section 5.4.1. However, this encapsulation of IPv6 traffic should 1143 be used as a last resort as described. IPv4 traffic is encapsulated 1144 in IPv6 packets to the home agent. 1146 When the mobile node is located in an IPv4 only network, it will send 1147 IPv6 packets to its home agent according to the following format: 1149 IPv4 header (src=V4CoA, dst=HA_V4ADDR) 1151 [UDP Header] 1153 IPv6 header (src=V6HoA, dst=CN) 1155 Upper Layer protocols 1157 Here the UDP header is only used if a NAT has been detected between 1158 the mobile node and the home agent, or if the home agent forced UDP 1159 encapsulation. V4CoA is the IPv4 care-of address configured by the 1160 mobile node in the visited network. 1162 Similarly, IPv4 packets are sent according to the following format: 1164 IPv4 header (src=V4CoA, dst=HA_V4ADDR) 1166 [UDP Header] 1168 IPv4 header (src=V4HoA, dst=V4CN) 1170 Upper Layer protocols 1172 Here the UDP header is only used if a NAT has been detected between 1173 the mobile node and the home agent, or if the home agent forced UDP 1174 encapsulation. 1176 5.4.4. Movement Detection in IPv4-only Networks 1178 [RFC3775] describes movement detection mostly based on IPv6-specific 1179 triggers and Neighbor Discovery [RFC4861] information. These 1180 triggers are not available in an IPv4-only network. Hence, a mobile 1181 node located in an IPv4-only network SHOULD use [RFC4436] for 1182 guidance on movement detection mechanisms in IPv4-only networks. 1184 The mobile node detects that it's in an IPv4-only network when the 1185 IPv6 movement detection algorithm fails to configure an IPv6 address. 1187 5.5. Home agent operation 1189 In addition to the home agent specification in [RFC3775] and 1190 [RFC3963], the home agent needs to be able to process the IPv4 home 1191 address option and generate the IPv4 address acknowledgement option. 1192 Both options are included in the mobility header. Furthermore, the 1193 home agent MUST be able to detect the presence of a NAT device and 1194 indicate that in the NAT detection option included in the binding 1195 acknowledgement. 1197 A home agent must also act as a proxy for address resolution in IPv4 1198 for the registered IPv4 home addresses of mobile nodes it is serving. 1199 Moreover, the administrative domain of the home agent is responsible 1200 for advertising the routing information of registered IPv4 mobile 1201 network prefixes of the mobile nodes. 1203 In order to comply with this specification, the home agent MUST be 1204 able to find the IPv4 home address of a mobile node when given the 1205 IPv6 home address. That is, given an IPv6 home address, the home 1206 agent MUST store the corresponding IPv4 home address if a static one 1207 is present. If a dynamic address were requested by the mobile node, 1208 the home agent MUST store that address (associated with the IPv6 home 1209 address) after it's allocated to the mobile node. 1211 When the home agent receives a binding update encapsulated in UDP and 1212 containing the IPv4 home address option, it needs to follow all the 1213 steps in [RFC3775] and [RFC3963]. In addition, the following checks 1214 MUST be done: 1216 o If the IPv4 care-of address in the IPv4 CoA option is not the same 1217 as the IPv4 address in the source address in the IPv4 header then 1218 a NAT was in the path. This information should be flagged for the 1219 binding acknowledgement. 1221 o If the F flag in the binding update were set, the home agent needs 1222 to determine whether it accepts forcing UDP encapsulation. If it 1223 does not, the binding acknowledgement is sent with error code 144. 1224 UDP encapsulation MUST NOT be used when the mobile node is located 1225 in an IPv6-enabled link. 1227 o If the IPv4 home address option contains a valid unicast IPv4 1228 address, the home agent MUST check that this address is allocated 1229 to the mobile node that has the IPv6 home address included in the 1230 home address option. The same MUST be done for an IPv4 prefix. 1232 o If the IPv4 home address option contained the unspecified IPv4 1233 address, the home agent SHOULD dynamically allocate an IPv4 home 1234 address to the mobile node. If none is available, the home agent 1235 MUST return error code 132 in the status field of the IPv4 address 1236 acknowledgement option. If a prefix were requested, the home 1237 agent SHOULD allocate a prefix with the requested length; if 1238 prefix allocation (of any length) was not possible, the home agent 1239 MUST indicate failure of the operation with the appropriate error 1240 code. 1242 o If the binding update is accepted for the IPv4 home address, the 1243 home agent creates a binding cache entry for the IPv4 home 1244 address/prefix. The home agent MUST include an IPv4 1245 acknowledgement option in the mobility header containing the 1246 binding acknowledgement. 1248 o If the binding update is accepted for both IPv4 and IPv6 home 1249 addresses, the home agent creates separate binding cache entries, 1250 one for each home address. The care-of address is the one 1251 included in the binding update. If the care-of address is an IPv4 1252 address, the home agent MUST setup a tunnel to the IPv4 care-of 1253 address of the mobile node. 1255 When sending a binding acknowledgement to the mobile node, the home 1256 agent constructs the message according to [RFC3775] and [RFC3963]. 1257 Note that the routing header MUST always contain the IPv6 home 1258 address as specified in [RFC3775]. 1260 If the care-of address of the mobile node were an IPv4 address, the 1261 home agent includes the mobile node's IPv6 home address in the 1262 destination address field in the IPv6 header. If a NAT were 1263 detected, the home agent MUST then encapsulate the packet in UDP and 1264 an IPv4 header. The source address is set to the home agent's IPv4 1265 address and the destination address is set to the address received in 1266 the source address of the IPv4 header encapsulating the binding 1267 update. 1269 After creating a binding cache entry for the mobile node's home 1270 addresses, all packets sent to the mobile node's home addresses are 1271 tunneled by the home agent to the mobile node's care-of address. If 1272 a NAT were detected, packets are encapsulated in UDP and IPv4. 1273 Otherwise, if the care-of address is an IPv4 address, and no NAT were 1274 detected, packets are encapsulated in an IPv4 header unless UDP 1275 encapsulation is forced by the home agent. 1277 5.5.1. Sending Packets to the Mobile Node 1279 The home agent follows the rules specified in [RFC3775] for sending 1280 IPv6 packets to mobile nodes located in IPv6 networks. When sending 1281 IPv4 packets to mobile nodes in an IPv6 network, the home agent must 1282 encapsulate the IPv4 packets in IPv6. 1284 When sending IPv6 packets to a mobile node located in an IPv4 1285 network, the home agent must follow the format negotiated in the 1286 binding update/acknowledgement exchange. In the absence of a 1287 negotiated format, the default format that MUST be supported by all 1288 implementations is: 1290 IPv4 header (src= HA_V4ADDR, dst= V4ADDR) 1292 UDP Header 1294 IPv6 header (src=CN, dst= V6HoA) 1296 Upper layer protocols 1298 Where the UDP header is only included if a NAT were detected between 1299 the mobile node and the home agent, or if the home agent forced UDP 1300 encapsulation. V4ADDR is the IPv4 address received in the source 1301 address field of the IPv4 packet containing the binding update. 1303 When sending IPv4 packets to a mobile node located in an IPv4 1304 network, the home agent must follow the format negotiated in the 1305 binding update/acknowledgement exchange. In the absence of a 1306 negotiated format, the default format that MUST be supported by all 1307 implementations is: 1309 IPv4 header (src= HA_V4ADDR, dst= V4ADDR) 1311 [UDP Header] 1313 IPv4 header (src=V4CN, dst= V4HoA) 1315 Upper layer protocols 1317 Where the UDP header is only included if a NAT were detected between 1318 the mobile node and home agent, or if the home agent forced UDP 1319 encapsulation. 1321 5.6. Correspondent Node Operation 1323 This specification has no impact on IPv4 or IPv6 correspondent nodes. 1325 6. Security Considerations 1327 This specification allows a mobile node to send one binding update 1328 for its IPv6 and IPv4 home addresses. This is a slight deviation 1329 from [RFC3775] which requires one binding update per home address. 1330 However, like [RFC3775], the IPsec security association needed to 1331 authenticate the binding update is still based on the mobile node's 1332 IPv6 home address. Therefore, in order to authorize the mobile 1333 node's IPv4 home address binding, the home agent MUST store the IPv4 1334 address corresponding to the IPv6 address that is allocated to a 1335 mobile node. Therefore, it is sufficient for the home agent to know 1336 that the IPsec verification for the packet containing the binding 1337 update was valid provided that it knows which IPv4 home address is 1338 associated with which IPv6 home address. Hence, the security of the 1339 IPv4 home address binding is the same as the IPv6 binding. 1341 In effect, associating the mobile node's IPv4 home address with its 1342 IPv6 home address moves the authorization of the binding update for 1343 the IPv4 address to the Mobile IPv6 implementation, which infers it 1344 from the fact that the mobile node has an IPv6 home address and the 1345 right credentials for sending an authentic binding update for the 1346 IPv6 address. 1348 This specification requires the use of IKEv2 as the default mechanism 1349 for dynamic keying. 1351 In cases where this specification is used for NAT traversal, it is 1352 important to note that it has the same vulnerabilities associated 1353 with [RFC3519]. An attacker is able to hijack the mobile node's 1354 session with the home agent if it can modify the contents of the 1355 outer IPv4 header. The contents of the header are not authenticated 1356 and there is no way for the home agent to verify their validity. 1357 Hence, a man in the middle attack where a change in the contents of 1358 the IPv4 header can cause a legitimate mobile node's traffic to be 1359 diverted to an illegitimate receiver independently of the 1360 authenticity of the binding update message. 1362 In this specification, the binding update message MUST be protected 1363 using ESP transport mode. When the mobile node is located in an 1364 IPv4-only network, the binding update message is encapsulated in UDP 1365 as described earlier. However, UDP SHOULD NOT be used to encapsulate 1366 the binding update message when the mobile node is located in an 1367 IPv6-enabled network. If protection of payload traffic is needed 1368 when the mobile node is located in an IPv4-only network, 1369 encapsulation is done using tunnel mode ESP over port 4500 as 1370 described in [RFC3948]. During the IKE negotiation with the home 1371 agent, if the mobile node and home agent support the use of port 1372 4500, the mobile node MUST establish the security association over 1373 port 4500, regardless of the presence of a NAT. This is done to 1374 avoid the switching between ports 500 and 4500 and the potential 1375 traffic disruption resulting from this switch. 1377 Handovers within private IPv4 networks or from IPv6 to IPv4 networks 1378 will have impacts on the security association between the mobile node 1379 and the home agent. The following section presents the expected 1380 behaviour of the mobile node and home agent in those situations. The 1381 details of the IKE negotiations and messages are illustrated in 1382 Section 6.2 1384 6.1. Handover Interactions for IPsec and IKE 1386 After the mobile node detects movement it configures a new care-of 1387 address. If the mobile node is in an IPv4-only network, it removes 1388 binding update list entries for correspondent nodes since route 1389 optimisation cannot be supported. This may cause inbound packet 1390 losses as remote correspondent nodes are unaware of such movement. 1391 To avoid confusion in the correspondent node, the mobile node SHOULD 1392 deregister its binding with each correspondent node by sending a 1393 deregistration binding update. The deregistration binding update 1394 message is tunnelled to the home agent and onto the correspondent 1395 node. This is done after the mobile node updates the home agent with 1396 its new location as discussed below. 1398 The mobile node sends the binding update message to the home agent. 1399 If the mobile node is in an IPv6-enabled network, the binding update 1400 is sent without IPv4/UDP encapsulation. If the mobile node is in an 1401 IPv4-only network, then after IPsec processing of the BU message, it 1402 encapsulates the BU in UDP/IPv4 as discussed in sections 5.2 and 5.4. 1403 In order to be able to send the binding update while in an IPv4-only 1404 network, the mobile node needs to use the new IPv4 care-of address in 1405 the outer header, which is different from the care-of address used in 1406 the existing tunnel. This should be done without permanently 1407 updating the tunnel within the mobile node's implementation in order 1408 to allow the mobile node to receive packets on the old care-of 1409 address until the binding acknowledgement is received. The method 1410 used to achieve this effect is implementation dependent and is 1411 outside the scope of this specification. This implies that the IP 1412 forwarding function (which selects the interface or tunnel through 1413 which a packet is sent) is not based solely on the destination 1414 address: some IPv6 packets destined to the home agent are sent via 1415 the existing tunnel, while BUs are sent using the new care-of 1416 address. Since BUs are protected by IPsec, the forwarding function 1417 cannot necessarily determine the correct treatment from the packet 1418 headers. Thus, the DSMIPv6 implementation has to attach additional 1419 information to BUs, and this information has to be preserved after 1420 IPsec processing and made available to the forwarding function, or 1421 additional DSMIP processing added to the forwarding function. 1422 Depending on the mobile node's implementation, meeting this 1423 requirement may require changes to the IPsec implementation. 1425 Upon receiving the binding update message encapsulated in UDP/IPv4, 1426 the home agent processes it as follows. In order to allow the 1427 DSMIPv6 implementation in the home agent to detect the presence of a 1428 NAT on the path to the mobile node, it needs to compare the outer 1429 IPv4 source address with the IPv4 address in the IPv4 care-of address 1430 option. This implies that the information in the outer header will 1431 be preserved after IPsec processing and made available to the DSMIPv6 1432 implementation in the home agent. Depending on the home agent's 1433 implementation, meeting this requirement may require changes to the 1434 IPsec implementation. 1436 The home agent updates its tunnel mode security association to 1437 include the mobile node's care-of address as the remote tunnel header 1438 address, and 4500 as the port number. The IPv4 address and port 1439 number are likely to be wrong; the mobile node provides the correct 1440 information in a separate exchange as described below. When the 1441 mobile node is located in a private IPv4 network (which is detected 1442 as described above), the new address and port number are allocated by 1443 the NAT. The home agent will also enable or disable UDP 1444 encapsulation for outgoing ESP packets for the purpose of NAT 1445 traversal. 1447 If the Key Management Mobility Capability (K) bit was set in the 1448 binding update, and the home agent supports this feature, the home 1449 agent updates its IKE security associations to include the mobile 1450 node's care-of address as the peer address and 4500 as the port 1451 number. The home agent may also need to change NAT traversal fields 1452 in the IKE_SA to enable the dynamic update of the IP address and port 1453 number based on the reception of authenticated IKE messages, or 1454 authenticated packets using tunnel mode ESP. The dynamic updates are 1455 described in section 2.23 of RFC 4306. As described above, when the 1456 mobile node is located in a private IPv4 network, the address and 1457 port number used for IPsec and IKE traffic is not yet known by the 1458 home agent at this point. 1460 The mobile node updates the IKE SA in one of two ways. If the K flag 1461 was set in the binding acknowledgement message, the mobile node 1462 SHOULD send an empty informational message, which results in the IKE 1463 module in the home agent to dynamically update the SA information. 1464 The IKE implementation in the home agent is REQUIRED to support this 1465 feature. Alternatively, the IKE SA should be re-negotiated. Note 1466 that updating the IKE SA MUST take place after the mobile node has 1467 sent the binding update and received the acknowledgement from the 1468 home agent. 1470 It is important to note that the mobile node's IPv4 care-of address 1471 seen by the DSMIPv6 module in the home agent upon receiving the 1472 binding update may differ from the IPv4 care-of address seen by the 1473 IKE module and the care-of address used for forwarding IPsec tunnel 1474 mode traffic. Hence, it is probable that different modules in the 1475 home agent will have a different care-of address that should be used 1476 for encapsulating traffic to the mobile node. 1478 After successfully processing the binding update, the home agent 1479 sends the binding acknowledgement to the mobile node's care-of 1480 address as received in the outer header of the packet containing the 1481 binding update. Note that if the BU was rejected, the BAck is sent 1482 to the same address where the BU was received from. This may require 1483 special treatment in IP forwarding and/or IPsec processing which 1484 resembles sending of BUs in the mobile node (described above). 1486 Upon receiving the binding acknowledgement, the mobile node updates 1487 its local tunnel mode Security Association information to include the 1488 tunnel header IP source address, which is the mobile node's address 1489 and the tunnel header IP destination, which is the home agent's 1490 address. The mobile node may also need to enable or disable UDP 1491 encapsulation for outgoing ESP packets for the purpose of NAT 1492 traversal and the sending of keep alives. 1494 The mobile node MAY use [RFC4555] to update its IKE SA with the home 1495 agent. Using MOBIKE requires negotiating this capability with the 1496 home agent when establishing the SA. In this case, the mobile node 1497 and the home agent MUST NOT update their IPsec SAs locally as this 1498 step is performed by MOBIKE. Furthermore, the use of MOBIKE allows 1499 the mobile node to update the SA independently of the binding update 1500 exchange. Hence, there is no need for the mobile node to wait for a 1501 binding acknowledgement before performing MOBIKE. The use of MOBIKE 1502 is OPTIONAL in this specification. 1504 6.2. IKE negotiation messages between the mobile node and Home Agent 1506 This specification defines a number of possible data encapsulation 1507 formats depending on the mobile node's connectivity to the visited 1508 network. When connected to an IPv6-enabled network, the tunnelling 1509 formats are clear. However, when connected to an IPv4-only network, 1510 care should be taken when negotiating the IKE association and the 1511 consequential tunnelling formats used for secure and insecure 1512 traffic. This section illustrates the IKE message exchange between 1513 the mobile node and home agent when the mobile node is located in an 1514 IPv4-only network. Two different IKE negotiations are considered: 1516 o IKEv2 operation for securing DSMIPv6 Signaling. 1518 o IKEv2 operation for securing Data over IPv4 1520 6.2.1. IKEv2 Operation for Securing DSMIPv6 Signaling 1522 A mobile node connected to an IPv4-only network SHOULD follow the 1523 procedures described below in order to establish an SA for the 1524 protection of binding update and binding acknowledgement messages. 1526 Mobile Node Home Agent 1527 ----------- ---------- 1528 IPv4(source_addr=V4ADDR, dest_addr=HAADDR) 1529 UDP (500, 500) HDR, SAi1, KEi, Ni 1530 NAT-D, NAT-D --> 1532 <- IPv4(source_addr=HAADDR, dest_addr=V4ADDR) 1533 UDP(500,X) HDR, SAr1, KEr, Nr, [CERTREQ] 1534 NAT-D, NAT-D 1536 IPv4(source_addr=V4ADDR, dest_addr=HAADDR) 1537 UDP (4500,4500) HDR, SK 1538 {IDi, [CERT,] [CERTREQ,] [IDr,] AUTH, N(USE_TRANSPORT_MODE), 1539 SAi2, TSi, TSr} 1540 --> 1542 <-- IPv4(source_addr=HAADDR, dest_addr=V4ADDR) 1543 UDP (4500,Y) HDR, SK 1544 {IDr, [CERT,] AUTH, N(USE_TRANSPORT_MODE), 1545 SAr2, TSi, TSr} 1547 The corresponding SPD entries are shown below. 1549 Mobile node SPD-S: 1551 IF local_address = home_address_1 & 1553 remote_address = home_agent_1 & 1555 proto = MH & local_mh_type = BU & remote_mh_type = BAck Then use 1556 SA ESP transport mode 1558 Initiate using IDi = user_1 to address home_agent_1 1560 Home Agent SPD-S: 1562 IF local_address = home_agent_1 & 1564 remote_address = home_address_1 & 1566 proto = MH & local_mh_type = BAck & remote_mh_type = BU Then use 1567 SA ESP transport mode 1569 where home_address_1 is the mobile node's registered IPv6 home 1570 address and home_agent_1 is the IP address of the home agent 1572 The above should result in BU/BA messages with the following BU 1573 received by the home agent. 1575 IPv4 header (src=V4ADDR, dst=HA_V4ADDR) 1577 UDP header (sport=Z, dport=DSMIPv6) 1579 IPv6 header (src=V6HOA, dst=HAADDR) 1581 ESP Header in Transport Mode 1583 Mobility header 1585 BU [IPv4 HAO] 1587 IPv4 CoA option 1589 (+ other as needed) 1591 At the home agent, following UDP de-capsulation, the binding update 1592 is delivered to the IPsec module as shown below: 1594 IPv6 header (src=V6HOA, dst=HAADDR) 1596 ESP Header in Transport Mode 1598 Mobility header 1600 BU [IPv4 HAO] 1602 IPv4 CoA option 1604 (+other as needed) 1606 In addition, V4ADDR and the sport (Z) need to be passed with the 1607 packet to ensure correct processing. 1609 Following IPsec processing, the binding update is delivered to the 1610 DSMIPv6 home agent module as follows: 1612 IPv6 header (src=V6HOA, dst=HAADDR) 1614 Mobility Header 1616 BU [IPv4 HAO] 1618 IPv4 CoA option 1620 (+other as needed) 1622 In addition, V4ADDR and the sport (Z) need to be passed with the 1623 packet to ensure correct processing. 1625 The binding acknowledgement sent by the home agent module to the 1626 IPsec module is as follows: 1628 IPv6 header (src=HAADDR, dst=V6HOA) 1630 Mobility Header 1632 BA ([IPv4 ACK], NAT DET) 1634 (+ other as needed) 1636 In addition, V4ADDR, the sport from the BU (Z), and an indication 1637 that UDP encapsulation must be used, need to be passed with the 1638 packet to ensure correct processing. 1640 The binding acknowledgement sent by the home agent to the mobile node 1641 is as follows: 1643 IPv4 header (src= HA_V4ADDR, dst=V4ADDR) 1645 UDP Header (sport=DSMIPv6, dport=Z) 1647 IPv6 header (src=HAADDR, dst=V6HOA) 1649 ESP Header in Transport Mode 1651 Mobility Header 1653 BA ([IPv4 ACK], NAT DET) 1655 6.2.2. IKEv2 Operation for Securing Data over IPv4 1657 To secure data traffic when the mobile node is located in an IPv4- 1658 only network, the mobile node MUST establish a child_SA for that 1659 purpose. The procedure is as follows: 1661 Mobile Node Home Agent 1662 ----------- ---------- 1663 IPv4(source_addr=V4ADDR, dest_addr=HAADDR) 1664 UDP (4500,4500) < non-ESP Marker > HDR, SK 1665 {[N], SA, Ni, [KEi], TSi, TSr} --> 1667 <--IPv4(source_addr=HAADDR, dest_addr=V4ADDR) 1668 UDP (4500,Y) < non-ESP Marker > HDR, SK 1669 SA, Nr, [KEr], TSi, TSr} 1671 If no NAT is detected, the encapsulation used will be: 1673 IPv4 (source_addr=v4CoA, dest_addr=HAAddr) 1675 ESP 1677 IP (source_addr=HoA, set_addr=CNAddr) 1679 Upper_layer_HDR 1681 where IP=IPv4 or IPv6 and HoA=v4HoA or v6HoA 1683 If a NAT were detected, the encapsulation used will be: 1685 IPv4 (source_addr=v4Addr, dest_addr=HAAddr) 1687 UDP (sport=Y, dport=4500) 1689 ESP 1691 IP (source_addr=HoA, set_addr=CNAddr) 1693 Upper_layer_HDR 1695 Where v4CoA may be the external IPv4 address of the NAT, IP is either 1696 an IPv4 or IPv6 header and HoA is either the IPv4 or the IPv6 HoA. 1697 The above format shows the packet as seen by the home agent. 1699 The SPD, whether a NAT were detected or not, is set as follows. Note 1700 that this rule is designed to match all data from the MN to nodes 1701 other than the home agent. This is done so that this rule does not 1702 overlap with the earlier rule securing BU/BA signaling between the MN 1703 and the HA. 1705 Mobile Node SPD-S: 1707 IF local_address = home_address & 1709 remote_address != home_agent & 1711 proto=any, then use SA ESP tunnel mode 1713 Initiate using IDi = user_1 to address home_agent_1 1715 home agent SPD-S: 1717 IF local_address != home_agent & 1719 remote_address = home_address & 1721 proto=any, then use SA ESP tunnel mode 1723 Where home_address is the MN's registered IPv6 or IPv4 home address 1724 and home_agent is the IPv6 or the IPv4 address of the home agent. 1726 7. Protocol Constants 1728 NATKATIMEOUT 110 seconds 1730 8. Acknowledgements 1732 Thanks to the following members (in alphabetical order) of the MIP6 1733 and NEMO Working Groups for their contributions, discussion, and 1734 review: Jari Arkko, Sri Gundavelli, Wassim Haddad, Conny Larsson, 1735 Acee Lindem, Ahmad Muhanna, Vidya Narayanan, Karen Nielsen and 1736 Keiichi Shima. Thanks to Karen Nielsen, Pasi Eronen and Christian 1737 Kaas-Petersen for raising the issue of IKEv2 interactions and 1738 proposing the solution included in this document. Thanks to Pasi 1739 Eronen for the many thorough reviews of this document. 1741 9. IANA Considerations 1743 The specification requires the following allocations from IANA: 1745 A UDP port is needed for the NAT traversal mechanism described in 1746 section 4.1. 1748 The IPv4 home address option described in section 3.1.1 requires 1749 an option type. This option is included in the Mobility header 1750 described in [RFC3775]. 1752 The IPv4 address acknowledgement option described in section 3.2.1 1753 requires a new option type. This option is included in the 1754 Mobility header described in [RFC3775]. 1756 The NAT detection option described in section 3.2.2 requires a new 1757 option type. This option is included in the Mobility header 1758 described in [RFC3775]. 1760 The IPv4 Care-of address option described in section 3.1.2 1761 requires a new option type allocation [RFC3775]. 1763 The Status field in the IPv4 home address option should be allocated 1764 by IANA under the new registry: "DSMIPv6 IPv4 home address option 1765 status codes". 1767 The status field values are allocated using the following procedure: 1769 1. New Status field values are allocated through IETF review. This 1770 is for all RFC types including standards track, informational, 1771 and experimental status that originate from the IETF and have 1772 been approved by the IESG for publication. 1774 2. Requests for new option type value assignments from outside the 1775 IETF are only made through the publication of an IETF document, 1776 per 1) above. Note also that documents published as "RFC Editor 1777 contributions" [RFC4844] are not considered to be IETF documents. 1779 10. References 1781 10.1. Normative References 1783 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1784 Requirement Levels", BCP 14, RFC 2119, March 1997. 1786 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 1787 IPv6 Specification", RFC 2473, December 1998. 1789 [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support 1790 in IPv6", RFC 3775, June 2004. 1792 [RFC3948] Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M. 1793 Stenberg, "UDP Encapsulation of IPsec ESP Packets", 1794 RFC 3948, January 2005. 1796 [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. 1797 Thubert, "Network Mobility (NEMO) Basic Support Protocol", 1798 RFC 3963, January 2005. 1800 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", 1801 RFC 4306, December 2005. 1803 [RFC4436] Aboba, B., Carlson, J., and S. Cheshire, "Detecting 1804 Network Attachment in IPv4 (DNAv4)", RFC 4436, March 2006. 1806 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1807 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1808 September 2007. 1810 [RFC4877] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with 1811 IKEv2 and the Revised IPsec Architecture", RFC 4877, 1812 April 2007. 1814 10.2. Informative 1816 [I-D.ietf-mip6-bootstrapping-integrated-dhc] 1817 Chowdhury, K. and A. Yegin, "MIP6-bootstrapping for the 1818 Integrated Scenario", 1819 draft-ietf-mip6-bootstrapping-integrated-dhc-06 (work in 1820 progress), April 2008. 1822 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 1823 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 1824 March 2000. 1826 [RFC2983] Black, D., "Differentiated Services and Tunnels", 1827 RFC 2983, October 2000. 1829 [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition 1830 of Explicit Congestion Notification (ECN) to IP", 1831 RFC 3168, September 2001. 1833 [RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, 1834 August 2002. 1836 [RFC3519] Levkowetz, H. and S. Vaarala, "Mobile IP Traversal of 1837 Network Address Translation (NAT) Devices", RFC 3519, 1838 April 2003. 1840 [RFC3978] Bradner, S., "IETF Rights in Contributions", RFC 3978, 1841 March 2005. 1843 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 1844 for IPv6 Hosts and Routers", RFC 4213, October 2005. 1846 [RFC4459] Savola, P., "MTU and Fragmentation Issues with In-the- 1847 Network Tunneling", RFC 4459, April 2006. 1849 [RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol 1850 (MOBIKE)", RFC 4555, June 2006. 1852 [RFC4844] Daigle, L. and Internet Architecture Board, "The RFC 1853 Series and RFC Editor", RFC 4844, July 2007. 1855 [RFC4977] Tsirtsis, G. and H. Soliman, "Problem Statement: Dual 1856 Stack Mobility", RFC 4977, August 2007. 1858 [RFC5026] Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6 1859 Bootstrapping in Split Scenario", RFC 5026, October 2007. 1861 [RFC5380] Soliman, H., Castelluccia, C., ElMalki, K., and L. 1862 Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility 1863 Management", RFC 5380, October 2008. 1865 [RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines 1866 for Application Designers", BCP 145, RFC 5405, 1867 November 2008. 1869 Appendix A. Contributors 1871 This document reflects discussions and contributions from several 1872 people including (in alphabetical order): 1874 Vijay Devarapalli: vijay.devarapalli@azairenet.com 1876 James Kempf: kempf@docomolabs-usa.com 1878 Henrik Levkowetz: henrik@levkowetz.com 1880 Pascal Thubert: pthubert@cisco.com 1882 George Tsirtsis: G.Tsirtsis@Qualcomm.com 1884 Wakikawa Ryuji: ryuji@sfc.wide.ad.jp 1886 Author's Address 1888 Hesham Soliman (editor) 1889 Elevate Technologies 1891 Email: hesham@elevatemobile.com