The Border Gateway Protocol (BGP) is an interautonomous system. （1）protocol. The primary function of a BGP speaking system is to exchange network（2）information with other BGP system. This network reachability information includes information on the list of Autonomous System (ASs) that teachability information traverses. BGP-4 provides a new set of mechanisms for supporting （3） interdomain routing. These mechanisms include support for advertising an IP （4）and eliminate the concept of network class within BGP. BGP-4 also introduces mechanisms that allow aggregation of routes, including（5）of AS paths. These changes provide support for the proposed supernettting scheme.
4（）
A.suffix
B.prefix
C.reflex
D.infix