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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


         <draft-dupont-durand-idr-ipv6-bgp-routerid-01.txt>


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
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   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)


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