Network Working Group Pedro R. Marques Internet Draft cisco Systems, Inc. Expiration Date: October 1998 April 1998 BGP-4 Capabilities Negotiation for BGP Multiprotocol Extensions draft-marques-bgp4-cap-mp-01.txt Status of this Memo 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." To view the entire list of current Internet-Drafts, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). 1. Abstract This document defines the usage of the BGP-4 Capabilities Negotiation parameter to negotiate the support for a particular Address Family, Sub-address Family pair between BGP-4 speakers using BGP-4 Multiprotocol Extensions. 2. Overview BGP-4 Multiprotocol Extensions [BGP-MP] define two optional non- transitive attributes that enable BGP-4 to carry routing information for multiple Network Layer protocols. Such attributes are ignored by BGP-4 when unrecognized either because the peer doesn't implement or is not configured to accept BGP-4 Multiprotocol Extensions or a given (AFI, SAFI) pair. The use of BGP-4 Capabilities Parameter [BGP-CAP] allows two peers to Marques [Page 1] Internet Draft draft-marques-bgp4-cap-mp-01.txt April 1998 negotiate the set of (AFI, SAFI) combinations supported on a particular peering relationship. This document defines a Capability Code that can be used for this purpose. 3. MP Capability Code BGP speakers that wish to negotiate the set of (AFI, SAFI) pairs availiable on a particular peering should use the MP_EXT Capability Code (Type 0x01, in hexadecimal). The Capability Value associated with the code is a 32 bit value, in network byte-order, defined as: 0 7 15 23 31 +-------+-------+-------+-------+ | AFI | Res. | SAFI | +-------+-------+-------+-------+ The use and meaning of this fields is as follows: AFI - Address Family Identifier (16 bit) as defined in [RFC- 1700]. Res. - Reserved (8 bit) field. Should be set to 0 by the sender and ignored by the receiver. SAFI - Subsequent Address Family Identifier (8 bit) field as defined in [BGP-MP] Each (AFI, SAFI) pair is encoded in the Capabilities Optional Parameter of a BGP-4 OPEN message as a separate triple . This allows the requester to identify which (AFI, SAFI) values are not supported by the peer on the receipt of a Unsupported Capability NOTIFICATION. Marques [Page 2] Internet Draft draft-marques-bgp4-cap-mp-01.txt April 1998 4. Security Considerations Security issues are not discussed in this document. 5. Acknowledgements To be supplied. 6. References [BGP-4] "A Border Gateway Protocol 4 (BGP-4)", Y. Rekhter and T. Li, RFC1771, March 1995. [BGP-CAP] "Capabilities Negotiation with BGP-4", R. Chandra and J. Scudder, Internet Draft, April 1998. [BGP-MP] "Multiprotocol Extensions for BGP-4", T. Bates, R. Chandra, D. Katz, and Y. Rekhter, RFC 2283, February 1998. [RFC1700] "Assigned Numbers", J. Reynolds and J. Postel, RFC 1700, October 1994. 7. Author Information Pedro R. Marques cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134 email: roque@cisco.com Marques [Page 3]