Border Gateway Protocol 3 (BGP-3) (RFC1267)
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2019-Feb-11
Internet Society Requests For Comment (RFCs)
K. Lougheed: AUTHOR [+1]
This memo, together with its companion document, "Application of the Border Gateway Protocol in the Internet", define an inter-autonomous system routing protocol for the Internet. [STANDARDS-TRACK]
Network Working Group K. Lougheed Request for Comments: 1267 cisco Systems Obsoletes RFCs: 1105, 1163 Y. Rekhter T.J. Watson Research Center, IBM Corp. October 1991
A Border Gateway Protocol 3 (BGP-3)
Status of this Memo
This memo, together with its companion document, "Application of the Border Gateway Protocol in the Internet", define an inter-autonomous system routing protocol for the Internet. This RFC specifies an IAB standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited.
We would like to express our thanks to Guy Almes (Rice University), Len Bosack (cisco Systems), Jeffrey C. Honig (Cornell Theory Center) and all members of the Interconnectivity Working Group of the Internet Engineering Task Force, chaired by Guy Almes, for their contributions to this document.
We like to explicitly thank Bob Braden (ISI) for the review of this document as well as his constructive and valuable comments.
We would also like to thank Bob Hinden, Director for Routing of the Internet Engineering Steering Group, and the team of reviewers he assembled to review earlier versions of this document. This team, consisting of Deborah Estrin, Milo Medin, John Moy, Radia Perlman, Martha Steenstrup, Mike St. Johns, and Paul Tsuchiya, acted with a strong combination of toughness, professionalism, and courtesy.
The Border Gateway Protocol (BGP) is an inter-Autonomous System routing protocol. It is built on experience gained with EGP as defined in RFC 904  and EGP usage in the NSFNET Backbone as described in RFC 1092  and RFC 1093 .
The primary function of a BGP speaking system is to exchange network reachability information with other BGP systems. This network reachability information includes information on the full path of
Lougheed & Rekhter [Page 1]
RFC 1267 BGP-3 October 1991
Autonomous Systems (ASs) that traffic must transit to reach these networks. This information is sufficient to construct a graph of AS connectivity from which routing loops may be pruned and some policy decisions at the AS level may be enforced.
To characterize the set of policy decisions that can be enforced using BGP, one must focus on the rule that an AS advertize to its neighbor ASs only those routes that it itself uses. This rule reflects the "hop-by-hop" routing paradigm generally used throughout the current Internet. Note that some policies cannot be supported by the "hop-by-hop" routing paradigm and thus require techniques such as source routing to enforce. For example, BGP does not enable one AS to send traffic to a neighbor AS intending that that traffic take a different route from that taken by traffic originating in the neighbor AS. On the other hand, BGP can support any policy conforming to the "hop-by-hop" rout...