The Border Gateway Protocol(BGP) is an interautonomous system   （ ）   protocol. The primary function of a BGP speaking system is to exchange network   （ ）   information with other BGP system. This network reachability information includes information on the list of Autonomous System(ASs) that reachability information traverses. BGP-4 provides a new set of mechanisms for supporting   （ ）   interdomain routing. These mechanisms include support for advertising an IP   （在此空作答）   and eliminate the concept of network class within BGP. BGP-4 also introduces mechanisms that allow aggregation of routes, including   （ ）   of AS paths. These changes provide support for the proposed supernetting scheme.