RFC 1163 (rfc1163) - Page 2 of 29

Border Gateway Protocol (BGP)

RFC 1163                          BGP                          June 1990


      6.3 UPDATE message error handling.........................   16
      6.4 NOTIFICATION message error handling...................   17
      6.5 Hold Timer Expired error handling.....................   17
      6.6 Finite State Machine error handling...................   18
      6.7 Cease.................................................   18
      7.  BGP Version Negotiation...............................   18
      8.  BGP Finite State machine..............................   18
      9.  UPDATE Message Handling...............................   22
      10. Detection of Inter-AS Policy Contradictions...........   23
      Appendix 1.  BGP FSM State Transitions and Actions........   25
      Appendix 2.  Comparison with RFC 1105.....................   28
      Appendix 3.  TCP options that may be used with BGP........   28
      References................................................   29
      Security Considerations...................................   29
      Authors' Addresses........................................   29

1.  Acknowledgements

   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 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.

2.  Introduction

   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 [1] and EGP usage in the NSFNET Backbone as
   described in RFC 1092 [2] and RFC 1093 [3].

   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
   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



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