Network Working Group P. Traina
Request for Comments: 1656 cisco Systems
Category: Informational July 1994
BGP-4 Protocol Document Roadmap and Implementation Experience
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Introduction
Border Gateway Protocol v4 (BGP-4) [1] is an inter-Autonomous System
routing protocol. It is built on experience gained with BGP as
defined in RFC-1267 [2] and BGP usage in the connected Internet as
described in RFC-1268 [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 list of
Autonomous Systems (ASs) that reachability information traverses.
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.
BGP-4 provides a new set of mechanisms for supporting classless
inter-domain routing. These mechanisms include support for
advertising an IP prefix and eliminates the concept of network
"class" within BGP. BGP-4 also introduces mechanisms which allow
aggregation of routes, including aggregation of AS paths. These
changes provide support for the proposed supernetting scheme [4].
The management information base has been defined [5] and security
considerations are discussed in the protocol definition document [1].
Applicability Statement for BGP-4
BGP-4 is explicitly designed for carrying reachability information
between Autonomous Systems. BGP-4 is not intended to replace
interior gateway protocols such as OSPF [7] or RIP [6].
Implementations
Four vendors have developed independent implementations at the time
of this memo:
Traina