Network Working Group Pedro R. Marques Internet Draft cisco Systems, Inc. Expiration Date: May 1998 November 1997 BGP-4 Capabilities Negotiation for BGP Multiprotocol Extensions draft-marques-bgp4-cap-mp-00.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 learn the current status of any Internet-Draft, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (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-00.txt November 1997 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 0x81, in hexadecimal). The high-order bit on this code is set to 1 meaning that this Capability is marked as "Required". 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-00.txt November 1997 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, August 1997. [BGP-MP] "Multiprotocol Extensions for BGP-4", T. Bates, R. Chandra, D. Katz, and Y. Rekhter, Internet Draft, September 1997. [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]