The Border Gateway Protocol (BGP) is an interautonomous system （71） protocol.The primary function of a BGP speaking system is to exchange network （72） 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 （73）interdomain routing. These mechanisms include support for advertising an IP （74） and eliminate the concept of network class within BGP.BGP-4 also introduces mechanisms that allow aggregation of routes, including （75） of AS paths. These changes provide support for the proposed supernettting scheme.

72（）

A．secubility

B．reachability

C．capability

D．reliability

新建文档WD12D.DOC，插入一个4行4列的表格，设置列宽为3厘米，行高为20磅，表格外框线设置为1.5磅实线，表内线设置为0.5磅实线，表线全部设置成蓝色；并将第1行的2、3列合并成一个单元格，将第1列的3、4行合并成一个单元格，存储为文档WD12D.DOC。