RFC 1655 (rfc1655) - Page 2 of 19

Application of the Border Gateway Protocol in the Internet

RFC 1655                   BGP-4 Application                   July 1994


   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
   (Spider).

   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
   document.

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
   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



Rekhter & Gross