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RFC 2119 keyword, line 233: '...ed. Hence, it is RECOMMENDED to use th...' Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (July 2, 2014) is 3585 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) -- Obsolete informational reference (is this intentional?): RFC 6506 (Obsoleted by RFC 7166) Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Draft I. Chen 3 A. Lindem 4 Category: Informational Ericsson 5 R. Atkinson 6 Consultant 7 Expires in 6 months July 2, 2014 9 OSPFv3 over IPv4 for IPv6 Transition 10 12 Status of this Memo 14 Distribution of this memo is unlimited. 16 This Internet-Draft is submitted in full conformance with the 17 provisions of BCP 78 and BCP 79. 19 Internet-Drafts are working documents of the Internet Engineering 20 Task Force (IETF), its areas, and its working groups. Note that 21 other groups may also distribute working documents as Internet- 22 Drafts. 24 Internet-Drafts are draft documents valid for a maximum of six months 25 and may be updated, replaced, or obsoleted by other documents at any 26 time. It is inappropriate to use Internet-Drafts as reference 27 material or to cite them other than as "work in progress." 29 The list of current Internet-Drafts can be accessed at 30 http://www.ietf.org/ietf/1id-abstracts.txt. 32 The list of Internet-Draft Shadow Directories can be accessed at 33 http://www.ietf.org/shadow.html. 35 This Internet-Draft will expire on date. 37 Copyright Notice 39 Copyright (c) 2014 IETF Trust and the persons identified as 40 the document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. 49 Abstract 51 This document defines a mechanism to use IPv4 to transport OSPFv3 52 packets, in order to facilitate transition from IPv4-only to IPv6 and 53 dual-stack within a routing domain. Using OSPFv3 over IPv4 with the 54 existing OSPFv3 Address Family extension can simplify transition from 55 an OSFPv2 IPv4-only routing domain to an OSPFv3 dual-stack routing 56 domain. 58 Table of Contents 60 1. Introduction ....................................................3 61 2. Encapsulation in IPv4 ...........................................4 62 2.1. Source Address .............................................6 63 2.2. Destination ................................................6 64 2.3. Operation over Virtual Link ................................6 65 3. IPv4-only Use Case ..............................................7 66 4. Security Considerations .........................................7 67 5. IANA Considerations .............................................8 68 6. References ......................................................8 70 1. Introduction 72 To facilitate transition from IPv4 [RFC791] to IPv6 [RFC2460], dual- 73 stack or IPv6 routing protocols should be gradually deployed. Dual- 74 stack routing protocols, such as Border Gateway Protocol [RFC4271], 75 have an advantage during the transition, because both IPv4 and IPv6 76 topologies can be transported using either IPv4 or IPv6. Some 77 IPv4-specific and IPv6-specific routing protocols share enough 78 similarities in their protocol packet formats and protocol signaling 79 that it is trivial to deploy an initial IPv6 routing domain by 80 carrying the routing protocol over IPv4 initially, thereby allowing 81 IPv6 routing domains be deployed and tested before decommissioning 82 IPv4 and moving to an IPv6-only network. 84 In the case of the Open Shortest Path First (OSPF) interior gateway 85 routing protocol (IGP), OSPFv2 [RFC2328] is the IGP deployed over 86 IPv4, while OSPFv3 [RFC5340] is the IGP deployed over IPv6. OSPFv3 87 further supports multiple address families [RFC5838], including both 88 the IPv6 unicast address family and the IPv4 unicast address family. 89 Consequently, it is possible to deploy OSPFv3 over IPv4 without any 90 changes either to OSPFv3 or to IPv4. During the transition to IPv6, 91 future OSPF extension can focus on OSPFv3 and OSPFv2 can move into 92 maintenance mode. 94 This document specifies how to use IPv4 packets to transport OSPFv3 95 packets. The mechanism takes advantage of the fact that OSPFv2 and 96 OSPFv3 share the same IP protocol number, 89. Additionally, the OSPF 97 packet header for both OSPFv2 and OSPFv3 places the OSPF header 98 version (i.e., the field that distinguishes an OSPFv2 packet from an 99 OSPFv3 packet) in the same location. 101 This document does not attempt to connect an IPv4 topology and an 102 IPv6 topology that are not congruent. In normal operation, it is 103 expected that the IPv4 topology within the OSPF domain will be 104 congruent with the IPv6 topology of that OSPF domain. In such cases, 105 it is expected either that all OSPFv3 packets will be transported 106 over IPv4 or that all OSPFv3 packets will be transported over IPv6. 108 If the IPv4 topology and IPv6 topology are not identical, the most 109 likely cause is that some parts of the network deployment have not 110 yet been upgraded to support both IPv4 and IPv6. In situations where 111 the IPv4 deployment is a proper superset of the IPv6 deployment, it 112 is expected that OSPFv3 packets would be transported over IPv4, until 113 the rest of the network deployment is upgraded to support IPv6 in 114 addition to IPv4. In situations where the IPv6 deployment is a 115 proper superset of the IPv4 deployment, it is expected that OSPFv3 116 would be transported over IPv6. 118 Throughout this document, OSPF is used when the text applies to both 119 OSPFv2 and OSPFv3. OSPFv2 or OSPFv3 is used when the text is 120 specific to one version of the OSPF protocol. Similarly, IP is used 121 when the text describes either version of the Internet protocol. 122 IPv4 or IPv6 is used when the text is specific to a single version of 123 the protocol. 125 2. Encapsulation in IPv4 127 Unlike 6to4 encapsulation [RFC3056] that tunnels IPv6 traffic through 128 an IPv4 network, an OSPFv3 packet can be directly encapsulated within 129 an IPv4 packet as the payload, without the IPv6 packet header, as 130 illustrated in Figure 1. For OSPFv3 transported over IPv4, the IPv4 131 packet has an IPv4 protocol type of 89, denoting that the payload is 132 an OSPF packet. The payload of the IPv4 packet consists of an OSPFv3 133 packet, beginning with the OSPF packet header with the OSPF version 134 number set to 3. 136 An OSPFv3 packet followed by an OSPF link-local signaling (LLS) 137 extension data block [RFC5613] encapsulated in an IPv4 packet is 138 illustrated in Figure 2. 140 0 1 2 3 141 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 1 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ^ 143 | 4 | IHL |Type of Service| Total Length | | 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 145 | Identification |Flags| Fragment Offset | | 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 | Time to Live | Protocol 89 | Header Checksum | IPv4 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Header 149 | Source Address | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 151 | Destination Address | | 152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 153 | Options | Padding | v 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ^ 155 | 3 | Type | Packet length | | 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 157 | Router ID | OSPFv3 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Header 159 | Area ID | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 161 | Checksum | Instance ID | 0 | | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ v 163 | OSPFv3 Body ... | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 Figure 1: An IPv4 packet encapsulating an OSPFv3 packet. 168 +---------------+ 169 | IPv4 Header | 170 +---------------+ 171 | OSPFv3 Header | 172 |...............| 173 | | 174 | OSPFv3 Body | 175 | | 176 +---------------+ 177 | | 178 | LLS Data | 179 | | 180 +---------------+ 182 Figure 2: The IPv4 packet encapsulating an OSPFv3 packet with 183 a trailing OSPF link-local signaling data block. 185 2.1. Source Address 187 For OSPFv3 over IPv4, the source address is the IPv4 interface 188 address for the interface over which the packet is transmitted. 189 All OSPFv3 routers on the link MUST share the same IPv4 subnet for 190 IPv4 transport to function correctly. 192 2.2. Destination Address 194 As defined in OSPFv2, the IPv4 destination address of an OSPF 195 protocol packet is either an IPv4 multicast address or the IPv4 196 unicast address of an OSPFv2 neighbor. Two well-known link-local 197 multicast addresses are assigned to OSPFv2, the AllSPFRouters 198 address (224.0.0.5) and the AllDRouters address (224.0.0.6). The 199 multicast address used depends on the OSPF packet type, the OSPF 200 interface type, and the OSPF router's role on multi-access 201 networks. 203 Thus, for an OSPFv3 over IPv4 packet to be sent to AllSPFRouters, 204 the destination address field in the IPv4 packet should be 205 224.0.0.5. For an OSPFv3 over IPv4 packet to be sent to 206 AllDRouters, the destination address field in the IPv4 packet 207 should be 224.0.0.6. 209 When an OSPF router sends a unicast OSPF packet over a connected 210 interface, the destination of such an IP packet is the address 211 assigned to the receiving interface. Thus, a unicast OSPFv3 packet 212 transported in an IPv4 packet would specify the OSPFv3 neighbor's 213 IPv4 address as the destination address. 215 2.3. Operation over Virtual Link 217 When an OSPF router sends an OSPF packet over a virtual link, the 218 receiving router is a router which is not directly connected to the 219 sending router. Thus, the destination IP address of the IP packet 220 must be a reachable unicast IP address of the receiving router. 221 Because IPv6 is the presumed Internet protocol and an IPv4 222 destination is not routable, the OSPFv3 address family extension 223 [RFC5838] specifies that only IPv6 address family virtual links are 224 supported. 226 As illustrated in Figure 1, this document specifies OSPFv3 227 transport over IPv4. As a result, an IPv4 packet in which the 228 destination field is a unicast IPv4 address assigned to the virtual 229 router is routable, and OSPFv3 virtual links in IPv4 unicast 230 address families can be supported. Hence, the restriction in 231 Section 2.8 of RFC 5838 [RFC5838] is removed. If IPv4 transport, 232 as specified herein, is used for IPv6 address families, virtual 233 links cannot be supported. Hence, it is RECOMMENDED to use the IP 234 transport matching the address family in OSPF routing domains 235 requiring virtual links. 237 3. IPv4-only Use Case 239 OSPFv3 only requires IPv6 link-local addresses to establish a routing 240 domain, and does not require IPv6 global-scope addresses to establish 241 a routing domain. However, IPv6 over Ethernet [RFC2464] uses a 242 different EtherType (0x86dd) from IPv4 (0x0800) and also from the 243 Address Resolution Protocol (ARP) (0x0806) [RFC826] that is used with 244 IPv4. 246 Some existing deployed link-layer equipment only supports IPv4 and 247 ARP. Such equipment contains hardware filters keyed on the EtherType 248 field of the Ethernet frame to filter which frames will be accepted 249 into that link-layer equipment. Because IPv6 uses a different 250 EtherType, IPv6 framing for OSPFv3 won't work with that equipment. 251 In other cases, PPP might be used over a serial interface, but again 252 only IPv4 over PPP might be supported over that interface. It is 253 hoped that equipment with such limitations will be replaced 254 eventually. 256 In some locations, especially locations with less communications 257 infrastructure, satellite communications (SATCOM) is used to reduce 258 deployment costs for data networking. SATCOM often has lower cost to 259 deploy than running new copper or optical cables for long distances 260 to connect remote areas. Also, in a wide range of locations 261 including places with good communications infrastructure, Very Small 262 Aperture Terminals (VSAT) often are used by banks and retailers to 263 connect their stores to their main offices. 265 Some widely deployed VSAT equipment has either (A) Ethernet 266 interfaces that only support Ethernet Address Resolution Protocol 267 (ARP) and IPv4, or (B) serial interfaces that only support IPv4 and 268 Point-to-Point Protocol (PPP) packets. Such deployments and 269 equipment still can deploy and use OSPFv3 over IPv4 today, and then 270 later migrate to OSPFv3 over IPv6 after equipment is upgraded or 271 replaced. This can have lower operational costs than running OSPFv2 272 and then trying to make a flag-day switch to running OSPFv3. By 273 running OSPFv3 over IPv4 now, the eventual transition to dual-stack, 274 and then to IPv6-only can be optimized. 276 4. Security Considerations 278 As described in [RFC4552], OSPFv3 uses IPsec [RFC4301] for 279 authentication and confidentiality. Consequently, an OSPFv3 packet 280 transported within an IPv4 packet requires IPsec to provide 281 authentication and confidentiality. Further work such as [ipsecospf] 282 would be required to support IPsec protection for OSPFv3 over IPv4 283 transport. 285 An optional OSPFv3 Authentication Trailer [RFC6506] also has been 286 defined as an alternative to using IPsec. The calculation of the 287 authentication data in the Authentication Trailer includes the source 288 IPv6 address to protect an OSPFv3 router from Man-in-the-Middle 289 attacks. For IPv4 encapsulation as described herein, the IPv4 source 290 address should be placed in the first 4 octets of Apad followed by 291 the hexadecimal value 0x878FE1F3 repeated (L-4)/4 times, where L is 292 the length of hash measured in octet. 294 The processing of the optional Authentication Trailer is contained 295 entirely within the OSPFv3 protocol. In other words, each OSPFv3 296 router instance is responsible for the authentication, without 297 involvement from IPsec or any other IP layer function. Consequently, 298 except for calculation of the value Apad, transporting OSPFv3 packets 299 using IPv4 does not change the operation of the optional OSPFv3 300 Authentication Trailer. 302 5. IANA Considerations 304 No actions are required from IANA as result of the publication of 305 this document. 307 6. References 309 6.1. Normative References 311 [RFC791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 312 1981. 314 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 315 (IPv6) Specification", RFC 2460, December 1998. 317 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 318 for IPv6", RFC 5340, July 2008. 320 [RFC2328] Moy, J., "OSPF Version 2", STD54, RFC 2328, April 1998. 322 [RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and 323 R. Aggarwal, "Support of Address Families in OSPFv3", RFC 324 5838, April 2010. 326 6.2. Informative References 328 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 329 Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 330 2006. 332 [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains 333 via IPv4 Clouds", RFC 3056, February 2001. 335 [RFC5613] Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D. 336 Yeung, "OSPF Link-Local Signaling", RFC 5613, August 2009. 338 [RFC826] Plummer, D., "Ethernet Address Resolution Protocol: Or 339 Converting Network Protocol Addresses to 48.bit Ethernet 340 Address for Transmission on Ethernet Hardware", STD 37, 341 RFC 826, November 1982. 343 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 344 Networks", RFC 2464, December 1998. 346 [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality 347 for OSPFv3", RFC 4552, June 2006. 349 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 350 Internet Protocol", RFC 4301, December 2005. 352 [RFC6506] Bhatia, M., Manral, V., and A. Lindem, "Supporting 353 Authentication Trailer for OSPFv3", RFC 6506, February 354 2012. 356 [ipsecospf] Gupta, M. and Melam, M, Work in progress, "draft-gupta- 357 ospf-ospfv2-sec-01.txt", August 2009. 359 Authors' Addresses 361 I. Chen 362 Ericsson 363 Email: ing-wher.chen@ericsson.com 365 A. Lindem 366 Ericsson 367 Email: acee.lindem@ericsson.com 369 R. Atkinson 370 Consultant