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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group F. Templin 3 Internet-Draft Boeing Phantom Works 4 Intended status: Informational T. Gleeson 5 Expires: March 10, 2008 Cisco Systems K.K. 6 D. Thaler 7 Microsoft Corporation 8 September 7, 2007 10 Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) 11 draft-templin-rfc4214bis-05.txt 13 Status of this Memo 15 By submitting this Internet-Draft, each author represents that any 16 applicable patent or other IPR claims of which he or she is aware 17 have been or will be disclosed, and any of which he or she becomes 18 aware will be disclosed, in accordance with Section 6 of BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF), its areas, and its working groups. Note that 22 other groups may also distribute working documents as Internet- 23 Drafts. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 The list of current Internet-Drafts can be accessed at 31 http://www.ietf.org/ietf/1id-abstracts.txt. 33 The list of Internet-Draft Shadow Directories can be accessed at 34 http://www.ietf.org/shadow.html. 36 This Internet-Draft will expire on March 10, 2008. 38 Copyright Notice 40 Copyright (C) The IETF Trust (2007). 42 Abstract 44 The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) connects 45 dual-stack (IPv6/IPv4) nodes over IPv4 networks. ISATAP views the 46 IPv4 network as a link layer for IPv6 and supports an automatic 47 tunneling abstraction similar to the Non-Broadcast Multiple Access 48 (NBMA) model. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 4. Domain of Applicability . . . . . . . . . . . . . . . . . . . 4 56 5. Node Requirements . . . . . . . . . . . . . . . . . . . . . . 4 57 6. Addressing Requirements . . . . . . . . . . . . . . . . . . . 4 58 6.1. ISATAP Interface Identifiers . . . . . . . . . . . . . . . 4 59 6.2. ISATAP Interface Address Configuration . . . . . . . . . . 5 60 6.3. Multicast/Anycast . . . . . . . . . . . . . . . . . . . . 5 61 7. Automatic Tunneling . . . . . . . . . . . . . . . . . . . . . 5 62 7.1. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 6 63 7.2. Handling ICMPv4 Errors . . . . . . . . . . . . . . . . . . 6 64 7.3. Decapsulation . . . . . . . . . . . . . . . . . . . . . . 6 65 7.4. Link-Local Addresses . . . . . . . . . . . . . . . . . . . 6 66 7.5. Neighbor Discovery over Tunnels . . . . . . . . . . . . . 6 67 8. Neighbor Discovery for ISATAP Interfaces . . . . . . . . . . . 7 68 8.1. Conceptual Model of a Host . . . . . . . . . . . . . . . . 7 69 8.2. Router and Prefix Discovery - Router Specification . . . . 7 70 8.3. Router and Prefix Discovery - Host Specification . . . . . 7 71 8.3.1. Host Variables . . . . . . . . . . . . . . . . . . . . 7 72 8.3.2. Potential Router List Initialization . . . . . . . . . 8 73 8.3.3. Processing Received Router Advertisements . . . . . . 8 74 8.3.4. Sending Router Solicitations . . . . . . . . . . . . . 8 75 8.4. Neighbor Unreachability Detection . . . . . . . . . . . . 9 76 9. Site Administration Considerations . . . . . . . . . . . . . . 9 77 10. Security Considerations . . . . . . . . . . . . . . . . . . . 9 78 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 79 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 80 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 81 13.1. Normative References . . . . . . . . . . . . . . . . . . . 11 82 13.2. Informative References . . . . . . . . . . . . . . . . . . 12 83 Appendix A. Modified EUI-64 Addresses in the IANA Ethernet 84 Address Block . . . . . . . . . . . . . . . . . . . . 12 85 Appendix B. Changes since RFC4214 . . . . . . . . . . . . . . . . 13 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 87 Intellectual Property and Copyright Statements . . . . . . . . . . 15 89 1. Introduction 91 This document specifies a simple mechanism called the Intra-Site 92 Automatic Tunnel Addressing Protocol (ISATAP) that connects dual- 93 stack (IPv6/IPv4) nodes over IPv4 networks. Dual-stack nodes use 94 ISATAP to automatically tunnel IPv6 packets in IPv4, i.e., ISATAP 95 views the IPv4 network as a link layer for IPv6. 97 ISATAP enables automatic tunneling whether global or private IPv4 98 addresses are used, and presents a Non-Broadcast Multiple Access 99 (NBMA) abstraction similar to [RFC2491][RFC2492][RFC2529][RFC3056]. 101 The main objectives of this document are to: 1) describe the domain 102 of applicability, 2) specify addressing requirements, 3) specify 103 automatic tunneling using ISATAP, 4) specify the operation of IPv6 104 Neighbor Discovery over ISATAP interfaces, and 5) discuss Site 105 Administration, Security, and IANA considerations. 107 2. Requirements 109 The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, 110 SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this 111 document, are to be interpreted as described in [RFC2119]. 113 This document also uses internal conceptual variables to describe 114 protocol behavior and external variables that an implementation must 115 allow system administrators to change. The specific variable names, 116 how their values change, and how their settings influence protocol 117 behavior are provided in order to demonstrate protocol behavior. An 118 implementation is not required to have them in the exact form 119 described here, as long as its external behavior is consistent with 120 that described in this document. 122 3. Terminology 124 The terminology of [RFC2460][RFC2461] applies to this document. The 125 following additional terms are defined: 127 ISATAP node/host/router: 128 A dual-stack (IPv6/IPv4) node/host/router that implements the 129 specifications in this document. 131 ISATAP interface: 132 An ISATAP node's Non-Broadcast Multi-Access (NBMA) IPv6 interface, 133 used for automatic tunneling of IPv6 packets in IPv4. 135 ISATAP interface identifier: 136 An IPv6 interface identifier with an embedded IPv4 address 137 constructed as specified in Section 6.1. 139 ISATAP address: 140 An IPv6 unicast address that matches an on-link prefix on an 141 ISATAP interface of the node, and that includes an ISATAP 142 interface identifier. 144 locator: 145 An IPv4 address-to-interface mapping; i.e., a node's IPv4 address 146 and its associated interface. 148 locator set: 149 A set of locators associated with an ISATAP interface. Each 150 locator in the set belongs to the same site. 152 4. Domain of Applicability 154 The domain of applicability for this technical specification is 155 automatic tunneling of IPv6 packets in IPv4 for ISATAP nodes within 156 sites that observe the security considerations found in this 157 document, including host-to-router, router-to-host, and host-to-host 158 automatic tunneling in certain enterprise networks and 3GPP/3GPP2 159 wireless operator networks. (Other scenarios with a sufficient trust 160 basis ensured by the mechanisms specified in this document also fall 161 within this domain of applicability.) 163 Extensions to the above domain of applicability (e.g., by combining 164 the mechanisms in this document with those in other technical 165 specifications) are out of the scope of this document. 167 5. Node Requirements 169 ISATAP nodes observe the common functionality requirements for IPv6 170 nodes found in [RFC4294] and the requirements for dual IP layer 171 operation found in [RFC4213], Section 2. They also implement the 172 additional features specified in this document. 174 6. Addressing Requirements 176 6.1. ISATAP Interface Identifiers 178 ISATAP interface identifiers are constructed in Modified EUI-64 179 format per [RFC4291], Section 2.5.1 by concatenating the 24-bit IANA 180 OUI (00-00-5E), the 8-bit hexadecimal value 0xFE, and a 32-bit IPv4 181 address in network byte order as follows: 183 |0 1|1 3|3 6| 184 |0 5|6 1|2 3| 185 +----------------+----------------+--------------------------------+ 186 |000000ug00000000|0101111011111110|mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm| 187 +----------------+----------------+--------------------------------+ 189 When the IPv4 address is known to be globally unique, the "u" bit 190 (universal/local) is set to 1; otherwise, the "u" bit is set to 0. 191 "g" is the individual/group bit, and "m" are the bits of the IPv4 192 address. 194 Per [RFC4291], Section 2.5.1, ISATAP nodes are not required to 195 validate that interface identifiers created with modified EUI-64 196 tokens with the "u" bit set to universal are unique. 198 6.2. ISATAP Interface Address Configuration 200 Each ISATAP interface configures a set of locators consisting of IPv4 201 address-to-interface mappings from a single site; i.e., an ISATAP 202 interface's locator set MUST NOT span multiple sites. 204 When an IPv4 address is removed from an interface, the corresponding 205 locator SHOULD be removed from its associated locator set(s). When a 206 new IPv4 address is assigned to an interface, the corresponding 207 locator MAY be added to the appropriate locator set(s). 209 ISATAP interfaces form ISATAP interface identifiers from IPv4 210 addresses in their locator set and use them to create link-local 211 ISATAP addresses ([RFC2462], Section 5.3). 213 6.3. Multicast/Anycast 215 It is not possible to assume the general availability of wide-area 216 IPv4 multicast, so (unlike 6over4 [RFC2529]) ISATAP must assume that 217 its underlying IPv4 carrier network only has unicast capability. 218 Support for IPv6 multicast over ISATAP interfaces is not described in 219 this document. 221 Similarly, support for Reserved IPv6 Subnet Anycast Addresses is not 222 described in this document. 224 7. Automatic Tunneling 226 ISATAP interfaces use the basic tunneling mechanisms specified in 228 [RFC4213], Section 3. The following sub-sections describe additional 229 specifications. 231 7.1. Encapsulation 233 ISATAP addresses are mapped to a link-layer address by a static 234 computation; i.e., the last four octets are treated as an IPv4 235 address. 237 7.2. Handling ICMPv4 Errors 239 ISATAP interfaces SHOULD process ARP failures and persistent ICMPv4 240 errors as link-specific information indicating that a path to a 241 neighbor may have failed ([RFC2461], Section 7.3.3). 243 7.3. Decapsulation 245 The specification in [RFC4213], Section 3.6 is used. Additionally, 246 when an ISATAP node receives an IPv4 protocol 41 datagram that does 247 not belong to a configured tunnel interface, it determines whether 248 the packet's IPv4 destination address and arrival interface match a 249 locator configured in an ISATAP interface's locator set. 251 If an ISATAP interface that configures a matching locator is found, 252 the decapsulator MUST verify that the packet's IPv4 source address is 253 correct for the encapsulated IPv6 source address. The IPv4 source 254 address is correct if: 256 o the IPv6 source address is an ISATAP address that embeds the IPv4 257 source address in its interface identifier, or 259 o the IPv4 source address is a member of the Potential Router List 260 (see Section 8.1). 262 Packets for which the IPv4 source address is incorrect for this 263 ISATAP interface are checked to determine whether they belong to 264 another tunnel interface. 266 7.4. Link-Local Addresses 268 ISATAP interfaces use link-local addresses constructed as specified 269 in Section 6 of this document. 271 7.5. Neighbor Discovery over Tunnels 273 ISATAP interfaces use the specifications for neighbor discovery found 274 in the following section of this document. 276 8. Neighbor Discovery for ISATAP Interfaces 278 ISATAP interfaces use the neighbor discovery mechanisms specified in 279 [RFC2461]. The following sub-sections describe specifications that 280 are also implemented. 282 8.1. Conceptual Model of a Host 284 To the list of Conceptual Data Structures ([RFC2461], Section 5.1), 285 ISATAP interfaces add the following: 287 Potential Router List (PRL) 288 A set of entries about potential routers; used to support router 289 and prefix discovery. Each entry ("PRL(i)") has an associated 290 timer ("TIMER(i)"), and an IPv4 address ("V4ADDR(i)") that 291 represents a router's advertising ISATAP interface. 293 8.2. Router and Prefix Discovery - Router Specification 295 Advertising ISATAP interfaces send Solicited Router Advertisement 296 messages as specified in [RFC2461], Section 6.2.6 except that the 297 messages are sent directly to the soliciting node; i.e., they might 298 not be received by other nodes on the link. 300 8.3. Router and Prefix Discovery - Host Specification 302 The Host Specification in [RFC2461], Section 6.3 is used. The 303 following sub-sections describe specifications added by ISATAP 304 interfaces. 306 8.3.1. Host Variables 308 To the list of host variables ([RFC2461], Section 6.3.2), ISATAP 309 interfaces add the following: 311 PrlRefreshInterval 312 Time in seconds between successive refreshments of the PRL after 313 initialization. The designated value of all ones (0xffffffff) 314 represents infinity. 316 Default: 3600 seconds 318 MinRouterSolicitInterval 319 Minimum time in seconds between successive solicitations of the 320 same advertising ISATAP interface. The designated value of all 321 ones (0xffffffff) represents infinity. 323 8.3.2. Potential Router List Initialization 325 ISATAP nodes initialize an ISATAP interface's PRL with IPv4 addresses 326 acquired via manual configuration, a DNS Fully Qualified Domain Name 327 (FQDN) [RFC1035], a DHCPv4 [RFC2131] vendor-specific option, or an 328 unspecified alternate method. Domain names are acquired via manual 329 configuration, receipt of a DHCPv4 Domain Name option [RFC2132], or 330 an unspecified alternate method. FQDNs are resolved into IPv4 331 addresses through a static host file lookup, querying the DNS 332 service, querying a site-specific name service, or with an 333 unspecified alternate method. 335 After initializing an ISATAP interface's PRL, the node sets a timer 336 for the interface to PrlRefreshInterval seconds and re-initializes 337 the interface's PRL as specified above when the timer expires. When 338 an FQDN is used, and when it is resolved via a service that includes 339 TTLs with the IPv4 addresses returned (e.g., DNS 'A' resource records 340 [STD13]), the timer SHOULD be set to the minimum of 341 PrlRefreshInterval and the minimum TTL returned. (Zero-valued TTLs 342 are interpreted to mean that the PRL is re-initialized before each 343 Router Solicitation event; see Section 8.3.4.) 345 8.3.3. Processing Received Router Advertisements 347 To the list of checks for validating Router Advertisement messages 348 ([RFC2461], Section 6.1.1), ISATAP interfaces add the following: 350 o IP Source Address is a link-local ISATAP address that embeds 351 V4ADDR(i) for some PRL(i). 353 Valid Router Advertisements received on an ISATAP interface are 354 processed as specified in [RFC2461], Section 6.3.4. 356 8.3.4. Sending Router Solicitations 358 To the list of events after which Router Solicitation messages may be 359 sent ([RFC2461], Section 6.3.7), ISATAP interfaces add the following: 361 o TIMER(i) for some PRL(i) expires. 363 Since unsolicited Router Advertisements may be incomplete and/or 364 absent, ISATAP nodes MAY schedule periodic Router Solicitation events 365 for certain PRL(i)s by setting the corresponding TIMER(i). 367 When periodic Router Solicitation events are scheduled, the node 368 SHOULD set TIMER(i) so that the next event will refresh remaining 369 lifetimes stored for PRL(i) before they expire, including the Router 370 Lifetime, Valid Lifetimes received in Prefix Information Options, and 371 Route Lifetimes received in Route Information Options [RFC4191]. 372 TIMER(i) MUST be set to no less than MinRouterSolicitInterval seconds 373 where MinRouterSolicitInterval is configurable for the node, or for a 374 specific PRL(i), with a conservative default value (e.g., 2 minutes). 376 When TIMER(i) expires, the node sends Router Solicitation messages as 377 specified in [RFC2461], Section 6.3.7 except that the messages are 378 sent directly to PRL(i); i.e., they might not be received by other 379 routers. While the node continues to require periodic Router 380 Solicitation events for PRL(i), and while PRL(i) continues to act as 381 a router, the node resets TIMER(i) after each expiration event as 382 described above. 384 8.4. Neighbor Unreachability Detection 386 ISATAP hosts SHOULD perform Neighbor Unreachability Detection 387 ([RFC2461], Section 7.3). ISATAP routers MAY perform neighbor 388 unreachability detection, but this might not scale in all 389 environments. 391 After address resolution, ISATAP hosts SHOULD perform an initial 392 reachability confirmation by sending Neighbor Solicitation messages 393 and receiving a Neighbor Advertisement message. ISATAP routers MAY 394 perform this initial reachability confirmation, but this might not 395 scale in all environments. 397 9. Site Administration Considerations 399 Site administrators maintain a Potential Router List (PRL) of IPv4 400 addresses representing advertising ISATAP interfaces of routers. 402 The PRL is commonly maintained as an FQDN for the ISATAP service in 403 the site's name service (see Section 8.3.2). There are no mandatory 404 rules for the selection of the FQDN, but site administrators are 405 encouraged to use the convention "isatap.domainname" (e.g., 406 isatap.example.com). 408 When the site's name service includes TTLs with the IPv4 addresses 409 returned, site administrators SHOULD configure the TTLs with 410 conservative values to minimize control traffic. 412 10. Security Considerations 414 Implementers should be aware that, in addition to possible attacks 415 against IPv6, security attacks against IPv4 must also be considered. 416 Use of IP security at both IPv4 and IPv6 levels should nevertheless 417 be avoided, for efficiency reasons. For example, if IPv6 is running 418 encrypted, encryption of IPv4 would be redundant unless traffic 419 analysis is felt to be a threat. If IPv6 is running authenticated, 420 then authentication of IPv4 will add little. Conversely, IPv4 421 security will not protect IPv6 traffic once it leaves the ISATAP 422 domain. Therefore, implementing IPv6 security is required even if 423 IPv4 security is available. 425 The threats associated with IPv6 Neighbor Discovery are described in 426 [RFC3756]. 428 There is a possible spoofing attack in which spurious ip-protocol-41 429 packets are injected into an ISATAP link from outside. Since an 430 ISATAP link spans an entire IPv4 site, restricting access to the link 431 can be achieved by restricting access to the site; i.e., by having 432 site border routers implement IPv4 ingress filtering and 433 ip-protocol-41 filtering. 435 Another possible spoofing attack involves spurious ip-protocol-41 436 packets injected from within an ISATAP link by a node pretending to 437 be a router. The Potential Router List (PRL) provides a list of IPv4 438 addresses representing advertising ISATAP interfaces of routers that 439 hosts use in filtering decisions. Site administrators should ensure 440 that the PRL is kept up to date, and that the resolution mechanism 441 (see Section 9) cannot be subverted. 443 The use of temporary addresses [RFC3041] and Cryptographically 444 Generated Addresses [RFC3972] on ISATAP interfaces is outside the 445 scope of this specification. 447 11. IANA Considerations 449 The IANA has specified the format for Modified EUI-64 address 450 construction ([RFC4291], Appendix A) in the IANA Ethernet Address 451 Block. The text in Appendix A of this document has been offered as 452 an example specification. The current version of the IANA registry 453 for Ether Types can be accessed at: 455 http://www.iana.org/assignments/ethernet-numbers 457 12. Acknowledgements 459 The ideas in this document are not original, and the authors 460 acknowledge the original architects. Portions of this work were 461 sponsored through SRI International, Nokia and Boeing internal 462 projects and government contracts. Government sponsors include 463 Monica Farah Stapleton and Russell Langan (U.S. Army CECOM ASEO), and 464 Dr. Allen Moshfegh (U.S. Office of Naval Research). SRI 465 International sponsors include Dr. Mike Frankel, J. Peter 466 Marcotullio, Lou Rodriguez, and Dr. Ambatipudi Sastry. 468 The following are acknowledged for providing peer review input: Jim 469 Bound, Rich Draves, Cyndi Jung, Ambatipudi Sastry, Aaron Schrader, 470 Ole Troan, and Vlad Yasevich. 472 The following are acknowledged for their significant contributions: 473 Marcelo Albuquerque, Brian Carpenter, Alain Durand, Hannu Flinck, 474 Jason Goldschmidt, Christian Huitema, Nathan Lutchansky, Karen 475 Nielsen, Mohan Parthasarathy, Chirayu Patel, Art Shelest, Markku 476 Savela, Pekka Savola, Margaret Wasserman, Brian Zill and members of 477 the IETF ipv6 and v6ops working groups. Mohit Talwar contributed to 478 earlier versions of this document. 480 The authors acknowledge the work done by Brian Carpenter and Cyndi 481 Jung in RFC2529 that introduced the concept of intra-site automatic 482 tunneling. This concept was later called: "Virtual Ethernet" and 483 researched by Quang Nguyen under the guidance of Dr. Lixia Zhang. 485 13. References 487 13.1. Normative References 489 [RFC1035] Mockapetris, P., "Domain names - implementation and 490 specification", STD 13, RFC 1035, November 1987. 492 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 493 Requirement Levels", BCP 14, RFC 2119, March 1997. 495 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 496 RFC 2131, March 1997. 498 [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor 499 Extensions", RFC 2132, March 1997. 501 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 502 (IPv6) Specification", RFC 2460, December 1998. 504 [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor 505 Discovery for IP Version 6 (IPv6)", RFC 2461, 506 December 1998. 508 [RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address 509 Autoconfiguration", RFC 2462, December 1998. 511 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 512 for IPv6 Hosts and Routers", RFC 4213, October 2005. 514 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 515 Architecture", RFC 4291, February 2006. 517 13.2. Informative References 519 [RFC2491] Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6 520 over Non-Broadcast Multiple Access (NBMA) networks", 521 RFC 2491, January 1999. 523 [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 524 Networks", RFC 2492, January 1999. 526 [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 527 Domains without Explicit Tunnels", RFC 2529, March 1999. 529 [RFC3041] Narten, T. and R. Draves, "Privacy Extensions for 530 Stateless Address Autoconfiguration in IPv6", RFC 3041, 531 January 2001. 533 [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains 534 via IPv4 Clouds", RFC 3056, February 2001. 536 [RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor 537 Discovery (ND) Trust Models and Threats", RFC 3756, 538 May 2004. 540 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 541 RFC 3972, March 2005. 543 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 544 More-Specific Routes", RFC 4191, November 2005. 546 [RFC4294] Loughney, J., "IPv6 Node Requirements", RFC 4294, 547 April 2006. 549 Appendix A. Modified EUI-64 Addresses in the IANA Ethernet Address 550 Block 552 Modified EUI-64 addresses ([RFC4291], Section 2.5.1 and Appendix A) 553 in the IANA Ethernet Address Block are formed by concatenating the 554 24-bit IANA OUI (00-00-5E) with a 40-bit extension identifier and 555 inverting the "u" bit; i.e., the "u" bit is set to one (1) to 556 indicate universal scope and set to zero (0) to indicate local scope. 558 Modified EUI-64 addresses have the following appearance in memory 559 (bits transmitted right-to-left within octets, octets transmitted 560 left-to-right): 562 0 23 63 563 | OUI | extension identifier | 564 000000ug00000000 01011110xxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 566 When the first two octets of the extension identifier encode the 567 hexadecimal value 0xFFFE, the remainder of the extension identifier 568 encodes a 24-bit vendor-supplied id as follows: 570 0 23 39 63 571 | OUI | 0xFFFE | vendor-supplied id | 572 000000ug00000000 0101111011111111 11111110xxxxxxxx xxxxxxxxxxxxxxxx 574 When the first octet of the extension identifier encodes the 575 hexadecimal value 0xFE, the remainder of the extension identifier 576 encodes a 32-bit IPv4 address as follows: 578 0 23 31 63 579 | OUI | 0xFE | IPv4 address | 580 000000ug00000000 0101111011111110 xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx 582 Appendix B. Changes since RFC4214 584 (RFC Editor Note: this section to be deleted before publication as an 585 RFC.) 587 o noted that ISATAP nodes are not required to validate that 588 interface identifiers with the 'u' bit set to universal are 589 unique. 591 o clarifications on Potential Router List initialization. 593 o clarifications in neighbor unreachability detection. 595 o updated acknowledgements; corrected historical background. 597 o updated references. 599 Authors' Addresses 601 Fred L. Templin 602 Boeing Phantom Works 603 P.O. Box 3707 MC 7L-49 604 Seattle, WA 98124 605 USA 607 Email: fred.l.templin@boeing.com 609 Tim Gleeson 610 Cisco Systems K.K. 611 Shinjuku Mitsui Building 612 2-1-1 Nishishinjuku, Shinjuku-ku 613 Tokyo 163-0409 614 Japan 616 Email: tgleeson@cisco.com 618 Dave Thaler 619 Microsoft Corporation 620 One Microsoft Way 621 Redmond, WA 98052-6399 622 US 624 Phone: +1 425 703 8835 625 Email: dthaler@microsoft.com 627 Full Copyright Statement 629 Copyright (C) The IETF Trust (2007). 631 This document is subject to the rights, licenses and restrictions 632 contained in BCP 78, and except as set forth therein, the authors 633 retain all their rights. 635 This document and the information contained herein are provided on an 636 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 637 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 638 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 639 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 640 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 641 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 643 Intellectual Property 645 The IETF takes no position regarding the validity or scope of any 646 Intellectual Property Rights or other rights that might be claimed to 647 pertain to the implementation or use of the technology described in 648 this document or the extent to which any license under such rights 649 might or might not be available; nor does it represent that it has 650 made any independent effort to identify any such rights. Information 651 on the procedures with respect to rights in RFC documents can be 652 found in BCP 78 and BCP 79. 654 Copies of IPR disclosures made to the IETF Secretariat and any 655 assurances of licenses to be made available, or the result of an 656 attempt made to obtain a general license or permission for the use of 657 such proprietary rights by implementers or users of this 658 specification can be obtained from the IETF on-line IPR repository at 659 http://www.ietf.org/ipr. 661 The IETF invites any interested party to bring to its attention any 662 copyrights, patents or patent applications, or other proprietary 663 rights that may cover technology that may be required to implement 664 this standard. Please address the information to the IETF at 665 ietf-ipr@ietf.org. 667 Acknowledgment 669 Funding for the RFC Editor function is provided by the IETF 670 Administrative Support Activity (IASA).