Network Working Group A. Lindem (Editor) Internet-Draft Redback Networks Intended status: Standards Track S. Mirtorabi Expires: October 7, 2007 Force10 Networks A. Roy M. Barnes Cisco Systems R. Aggarwal Juniper Networks April 5, 2007 Support of address families in OSPFv3 draft-ietf-ospf-af-alt-05.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on October 7, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Lindem (Editor), et al. Expires October 7, 2007 [Page 1] Internet-Draft OSPFv3 AF April 2007 Abstract This document describes a mechanism for supporting multiple address families in OSPFv3 using multiple instances. It maps an address family (AF) to an OSPFv3 instance using the Instance ID field in the OSPFv3 packet header. This approach is fairly simple and minimizes extensions to OSPFv3 for supporting multiple AFs. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Design Considerations . . . . . . . . . . . . . . . . . . 3 1.2. Requirements notation . . . . . . . . . . . . . . . . . . 3 2. Protocol Details . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Instance ID values for new AFs . . . . . . . . . . . . . . 4 2.2. OSPFv3 Options and Prefix Options Changes . . . . . . . . 4 2.2.1. OSPFv3 Options . . . . . . . . . . . . . . . . . . . . 4 2.2.2. Prefix Options . . . . . . . . . . . . . . . . . . . . 5 2.3. Advertising Prefixes in new AFs . . . . . . . . . . . . . 5 2.4. Changes to the Hello processing . . . . . . . . . . . . . 6 2.5. Next hop for IPv4 unicast and multicast AFs . . . . . . . 6 2.6. Operation over Virtual Links . . . . . . . . . . . . . . . 7 3. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 8 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.1. Normative References . . . . . . . . . . . . . . . . . . . 12 6.2. Informative References . . . . . . . . . . . . . . . . . . 12 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Intellectual Property and Copyright Statements . . . . . . . . . . 15 Lindem (Editor), et al. Expires October 7, 2007 [Page 2] Internet-Draft OSPFv3 AF April 2007 1. Introduction OSPFv3 has been defined to support the base IPv6 unicast Address Family (AF). There is a requirement to advertise other AFs in OSPFv3 including multicast IPv6, unicast IPv4, and multicast IPv4. This document supports these other AFs in OSPFv3 by mapping each to a separate Instance ID and OSPFv3 instance. 1.1. Design Considerations This section describes the rationale for using the multiple instance ID approach to support multiple address families in OSPFv3. As described earlier, OSPFv3 is designed to support multiple instances. Hence mapping an instance to an address family doesn't introduce any new mechanisms to the protocol. It minimizes the protocol extensions required and it simplifies the implementation. The presence of a separate link state database per address family is also easier to debug and operate. Additionally, it doesn't change the existing instance, area, and interface based configuration model in most OSPFv3 implementations. 1.2. Requirements notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC-KEYWORDS]. Lindem (Editor), et al. Expires October 7, 2007 [Page 3] Internet-Draft OSPFv3 AF April 2007 2. Protocol Details Currently the entire Instance ID number space is used for IPv6 unicast. This specification assigns different Instance ID ranges to different AFs in order to support other AFs in OSPFv3. Each Instance ID implies a separate OSPFv3 instance with its own neighbor adjacencies, link state database, protocol data structures, and shortest path first (SPF) computation. Additionally, the current LSAs that are defined to advertise IPv6 unicast prefixes can be used without any modifications to advertise prefixes from other AFs. It should be noted that OSPFv3 is running on the top of IPv6 and uses IPv6 link local addresses for OSPFv3 control packets and next hop calculations. Therefore, it is required that IPv6 be enabled on a link, although the link may not be participating in the IPv6 unicast AF. 2.1. Instance ID values for new AFs Instance ID zero is already defined by default for the IPv6 unicast AF. We define the following ranges for different AFs. The first value of each range is considered as the default value for the corresponding AF. Instance ID # 0 - # 31 IPv6 unicast AF Instance ID # 32 - # 63 IPv6 multicast AF Instance ID # 64 - # 95 IPv4 unicast AF Instance ID # 96 - # 127 IPv4 multicast AF Instance ID # 128 - # 255 Unassigned OSPFv3 Instance IDs 2.2. OSPFv3 Options and Prefix Options Changes A new bit is added to the OSPFv3 options field. A couple of the option bits are only applicable to the IPv6 unicast AF. 2.2.1. OSPFv3 Options 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+--+-+-+--+--+--+ | | | | | | | | | | | | | | | |AF|*|*|DC|R|N|MC| E|V6| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+--+-+-+--+--+--+ The Options field Lindem (Editor), et al. Expires October 7, 2007 [Page 4] Internet-Draft OSPFv3 AF April 2007 OSPFv3 Options V6-bit The V6 bit is used in OSPFv3 to exclude a node from IPv6 unicast route calculation but allow it in the SPF calculation for other address families. Since Instance ID now denotes the AF explicitly, this bit is ignored in AFs other than IPv6 unicast. MC-bit This bit is not used in other AFs introduced in this document. AF-bit When a router supports AF, it MUST set this new bit in the OSPFv3 Options field of Hello Packets, DD packets, and LSAs. 2.2.2. Prefix Options 0 1 2 3 4 5 6 7 +--+--+--+--+--+--+--+--+ | | | | | P|* |LA|NU| +--+--+--+--+--+--+--+--+ Prefix Options MC-bit This bit is ignored in AFs other than IPv6 Unicast. NU-bit The NU bit MUST be clear in all unicast AFs and it MUST be set in all multicast AFs. Note that all bits unused in a given AF MAY be redefined for AF specific purposes in future specifications. 2.3. Advertising Prefixes in new AFs Each Prefix defined in OSPFv3 has a prefix length field. This facilitate advertising prefixes of different lengths in different AFs. The existing LSAs defined in OSPFv3 are used for this purpose and there is no need to define new LSAs. Lindem (Editor), et al. Expires October 7, 2007 [Page 5] Internet-Draft OSPFv3 AF April 2007 2.4. Changes to the Hello processing When a router does not support an AF but it is configured the corresponding Instance ID packets could be black holed. This could happen due to misconfiguration or a router software downgrade. Black holing is possible because the router which doesn't support the AF can still be included in the SPF calculated path as long as it establishes adjacencies using the Instance ID corresponding to the AF. Note that router and network LSAs are AF independent. In order to avoid the above situation, hello processing is changed in order to only establish adjacencies with routers that have the AF-bit set in their Options field. Receiving Hello Packets is specified in section 3.2.2.1 of [OSPFV3]. The following check is added to Hello reception: o When a router participates in an AF (sets the AF-bit in Options field) it MUST discard Hello packets having the AF-bit clear in the Options field. The only exception is IPv6 unicast AF, where this check MUST NOT be done (for backward compatibility). 2.5. Next hop for IPv4 unicast and multicast AFs OSPFv3 runs on the top of IPv6 and uses IPv6 link local addresses for OSPFv3 control packets and next hop calculations. Although IPV6 link local addresses could be used as next hops for IPv4 address families, it is desirable to have IPv4 next hop addresses. For example, in IPv4 multicast having the next hop address the same as the Protocol Independent Multicast (PIM) [PIM] neighbor address (IPv4 address) makes it easier to determine which upstream neighbor to send a PIM join when doing a Reverse Path Forwarding (RPF) lookup. It is also easier for troubleshooting to have a next hop with the same AF. In order to achieve this, the link's IPv4 address will be advertised in the "link local address" field of the IPv4 instance's Link-LSA. This address is placed in the first 32 bit of "link local address" field and used for IPv4 next hop calculations. We call direct interface address (DIA) the address that is reachable directly via the link provided that a layer 3 to layer 2 mapping is available. Note that there is no explicit need for the IPv4 link addresses to be on the same subnet. An implementation should resolve layer 3 to layer 2 mappings via Address Resolution Protocol (ARP) [ARP] or Neighbor Discovery (ND) [ND] for a DIA even if the IPv4 address is not on the same subnet as the router's interface IP address. Lindem (Editor), et al. Expires October 7, 2007 [Page 6] Internet-Draft OSPFv3 AF April 2007 2.6. Operation over Virtual Links OSPFv3 control packets sent over a virtual link are IPv6 packets and may traverse multiples hops. Therefore, there must be a global IPv6 address associated with the virtual link so that the control packet is forwarded correctly by the intermediate hops between virtual link endpoints. Although this requirement can be satisfied in IPv6 unicast AFs, it will not function in other AFs as there will not be a routable global IPv6 address or forwarding path. Therefore, virtual links are not supported in AFs other than IPv6 Unicast. Lindem (Editor), et al. Expires October 7, 2007 [Page 7] Internet-Draft OSPFv3 AF April 2007 3. Backward Compatibility In this section, we will define a non-capable OSPFv3 router as one not supporting this specification. Each new AF will have a corresponding Instance ID and can interoperate with the existing non- capable OSPFv3 routers in an IPv6 unicast topology. Furthermore, when a non-capable OSPFv3 router uses an Instance ID which is reserved for a given AF, no adjacency will be formed with this router since the AF-bit in the Options field will not be set in Hello packets. Therefore, there are no backward compatibility issues. AFs can be gradually deployed without disturbing networks with non- capable OSPFv3 routers. Lindem (Editor), et al. Expires October 7, 2007 [Page 8] Internet-Draft OSPFv3 AF April 2007 4. Security Considerations The function described in this document does not create any new security issues for the OSPF protocol. Security considerations for the OSPFv3 are covered in [OSPFV3]. Lindem (Editor), et al. Expires October 7, 2007 [Page 9] Internet-Draft OSPFv3 AF April 2007 5. IANA Considerations The following IANA assignments are to be made from existing registries: o An OSPFv3 options bit will be allocated for support of address families using separate instances. IANA is requested to create a new registry, "OSPFv3 Instance ID Address Family Values". for assignment of address families IDs. Note that the Instance ID MAY be used for applications other than the support of multiple address families. However, if it is being used for address families the assignments herein should be honored. +-------------+----------------------+--------------------+ | Value/Range | Designation | Assignment Policy | +-------------+----------------------+--------------------+ | 0 | Base IPv6 Unicast AF | Already assigned | | | | | | 1-31 | IPv6 Unicast AFs | Already assigned | | | dependent on local | | | | policy | | | | | | | 32 | Base IPv6 Multicast | Already assigned | | | | | | 33-63 | IPv6 Multicast AFs | Already assigned | | | dependent on local | | | | policy | | | | | | | 64 | Base IPv4 Unicast AF | Already assigned | | | | | | 65-95 | IPv4 Unicast AFs | Already assigned | | | dependent on local | | | | policy | | | | | | | 96 | Base IPv4 Multicast | Already assigned | | | | | | 97-127 | IPv4 Multicast AFs | Already assigned | | | dependent on local | | | | policy | | | | | | | 128-255 | Unassigned | Standards Action | +-------------+----------------------+--------------------+ OSPFv3 Address Family Use of Instance IDs Lindem (Editor), et al. Expires October 7, 2007 [Page 10] Internet-Draft OSPFv3 AF April 2007 o Instancs IDs 0-127 are assigned by this specification. o Instance IDs in the range 128-255 are not assigned at this time. Before any assignments can be made in this range, there MUST be a Standards Track RFC including IANA Considerations explicitely specifying the AF Instance IDs being assigned. Lindem (Editor), et al. Expires October 7, 2007 [Page 11] Internet-Draft OSPFv3 AF April 2007 6. References 6.1. Normative References [OSPFV3] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6", RFC 2740, December 1999. [RFC-KEYWORDS] Bradner, S., "Key words for use in RFC's to Indicate Requirement Levels", RFC 2119, March 1997. 6.2. Informative References [ARP] Plummer, D., "An Ethernet Address Resolution Protocol", RFC 826, November 1982. [ND] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [PIM] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, August 2006. Lindem (Editor), et al. Expires October 7, 2007 [Page 12] Internet-Draft OSPFv3 AF April 2007 Appendix A. Acknowledgments The RFC text was produced using Marshall Rose's xml2rfc tool. Thanks to Tom Henderson and the folks at Boeing for implementing in quagga. Lindem (Editor), et al. Expires October 7, 2007 [Page 13] Internet-Draft OSPFv3 AF April 2007 Authors' Addresses Acee Lindem Redback Networks 102 Carric Bend Court Cary, NC 27519 USA Email: acee@redback.com Sina Mirtorabi Force10 Networks 350 Holger Way San Jose, CA 95134 USA Email: sina@force10networks.com Abhay Roy Cisco Systems 225 West Tasman Drive San Jose, CA 95134 USA Email: akr@cisco.com Michael Barnes Cisco Systems 225 West Tasman Drive San Jose, CA 95134 USA Email: mjbarnes@cisco.com Rahul Aggarwal Juniper Networks 1194 N. Mathilda Ave. Sunnyvale, CA 94089 USA Email: rahul@juniper.net Lindem (Editor), et al. Expires October 7, 2007 [Page 14] Internet-Draft OSPFv3 AF April 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Lindem (Editor), et al. Expires October 7, 2007 [Page 15]