Internet Engineering Task Force Francis Dupont INTERNET DRAFT ENST Bretagne Expires in July 2002 Alain Durand January 2. 2002 BGP4 router ID for IPv6 only routers Status of this Memo This document is an Internet Draft and is in full conformance with all provisions of Section 10 of RFC 2026. This document is an Internet-Draft. 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. Distribution of this memo is unlimited. Abstract BGP4 [1] uses a 32 bit field to identify router (the so called "router-IDs"). In IPv4 domain, an IPv4 address of the router is typically used in this field. In an IPv6 routing domain, routers may very well not have any IPv4 Addresses. This document provides a simple way to form a globally Unique ID in such a case. 1. Introduction BGP4 [1] extension for IPv6 are defined in [2] and [3]. However, BGP4 uses a 32 bit field known as the router ID. This router ID is used in: BGP4 [1] uses the router ID as an identifier in: - BGP Identifier in OPEN messages (local use) - AGGREGATOR (optional transitive) attributes - ORIGINATOR_ID (optional non-transitive) attributes [4] - CLUSTER_LIST (optional non-transitive) attributes [4] The AGGREGATOR attributes contain an Autonomous System (AS) number with the IP address of the BGP speaker that formed the aggregate route. It is the only transitive, (i.e. non local) use of the router ID. The router ID should be somehow unique and BGP implementations should provide a way to manually set it. This field typically contains one of the IPv4 addresses of the BGP4 speaker. In an IPv6 domain, some router may have IPv4 addresses, and some other may very well not have any. On those routers, one can not assigned random values to the router ID, as it could conflict with the router ID derived from an IPv4 addresses on another dual stack router. This document specifies a simple way to construct a somehow globally unique 32 bit router ID. 2. Recommended practice In the absence of a globally unique IPv4 address on the router, the 32 bit routing ID may be constructed with: - 4 bits set to one (as for an old reserved class E IPv4 address), - 16 bits set to the AS number (a global AS number SHOULD be used if the router ID can be seen outside the routing domain). - 12 bits manually allocated within the domain. This allows for 4096 different router IDs in each routing domain. 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 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 +-------+-------------------------------+-----------------------+ | | | | | 0xF | AS Number | Locally allocated | | | | | +-------+-------------------------------+-----------------------+ Note: 32 bit AS numbers could be introduced in the future. This recommended solution would then have to be adapted. 3. Security Considerations The usage of fake IPv4 address of this form minimizes accidental or deliberate confusions (ie. same router ID for two different BGP speakers). 4. References [1] Y. Rekhter, T. Li, "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995. [2] T. Bates, Y. Rekhter, R. Chandra, D. Katz, "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000. [3] P. Marques, F. Dupont, "Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing", RFC 2545, March 1999. [4] T. Bates, R. Chandra, E. Chen, "BGP Route Reflection - An Alternative to Full Mesh IBGP", RFC 2796, April 2000. 5. Author's Address Francis Dupont ENST Bretagne Campus de Rennes 2, rue de la Chataigneraie BP 78 35512 Cesson-Sevigne Cedex FRANCE Fax: +33 2 99 12 70 30 EMail: Francis.Dupont@enst-bretagne.fr Alain Durand SUN Microsystems, Inc 901 San Antonio Road MPK17-202 Palo Alto, CA 94303-4900 USA EMail: Alain.Durand@sun.com Expire in 6 months (July 3, 2002)