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