Application of the Border Gateway Protocol in the Internet
RFC 1772

Document Type RFC - Draft Standard (March 1995; No errata)
Obsoletes RFC 1655
Last updated 2013-03-02
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Network Working Group                                         Y. Rekhter
Request for Comments: 1772        T.J. Watson Research Center, IBM Corp.
Obsoletes: 1655                                                 P. Gross
Category: Standards Track                                            MCI
                                                              March 1995

       Application of the Border Gateway Protocol in the Internet

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.


   This document, together with its companion document, "A Border
   Gateway Protocol 4 (BGP-4)", define an inter-autonomous system
   routing protocol for the Internet.  "A Border Gateway Protocol 4
   (BGP-4)" defines the BGP protocol specification, and this document
   describes the usage of the BGP in the Internet.

   Information about the progress of BGP can be monitored and/or
   reported on the BGP mailing list (


   This document was originally published as RFC 1164 in June 1990,
   jointly authored by Jeffrey C. Honig (Cornell University), Dave Katz
   (MERIT), Matt Mathis (PSC), Yakov Rekhter (IBM), and Jessica Yu

   The following also made key contributions to RFC 1164 -- Guy Almes
   (ANS, then at Rice University), Kirk Lougheed (cisco Systems), Hans-
   Werner Braun (SDSC, then at MERIT), and Sue Hares (MERIT).

   We like to explicitly thank Bob Braden (ISI) for the review of the
   previous version of this document.

   This updated version of the document is the product of the IETF BGP
   Working Group with Phill Gross (MCI) and Yakov Rekhter (IBM) as

Rekhter & Gross                                                 [Page 1]
RFC 1772                   BGP-4 Application                  March 1995

   John Moy (Proteon) contributed Section 7 "Required set of supported
   routing policies".

   Scott Brim (Cornell University) contributed the basis for Section 8
   "Interaction with other exterior routing protocols".

   Most of the text in Section 9 was contributed by Gerry Meyer

   Parts of the Introduction were taken almost verbatim from [3].

   We would like to acknowledge Dan Long (NEARNET) and Tony Li (cisco
   Systems) for their review and comments on the current version of the

   The work of Yakov Rekhter was supported in part by the National
   Science Foundation under Grant Number NCR-9219216.

1. Introduction

   This memo describes the use of the Border Gateway Protocol (BGP) [1]
   in the Internet environment. BGP is an inter-Autonomous System
   routing protocol. The network reachability information exchanged via
   BGP provides sufficient information to detect routing loops and
   enforce routing decisions based on performance preference and policy
   constraints as outlined in RFC 1104 [2]. In particular, BGP exchanges
   routing information containing full AS paths and enforces routing
   policies based on configuration information.

   As the Internet has evolved and grown over in recent years, it has
   become painfully evident that it is soon to face several serious
   scaling problems. These include:

       - Exhaustion of the class-B network address space. One
         fundamental cause of this problem is the lack of a network
         class of a size which is appropriate for mid-sized
         organization; class-C, with a maximum of 254 host addresses, is
         too small while class-B, which allows up to 65534 addresses, is
         too large to be densely populated.

       - Growth of routing tables in Internet routers are beyond the
         ability of current software (and people) to effectively manage.

       - Eventual exhaustion of the 32-bit IP address space.

   It has become clear that the first two of these problems are likely
   to become critical within the next one to three years.  Classless
   inter-domain routing (CIDR) attempts to deal with these problems by

Rekhter & Gross                                                 [Page 2]
RFC 1772                   BGP-4 Application                  March 1995

   proposing a mechanism to slow the growth of the routing table and the
   need for allocating new IP network numbers. It does not attempt to
   solve the third problem, which is of a more long-term nature, but
   instead endeavors to ease enough of the short to mid-term
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