2. 计算机
  3. Border Gateway Protocol(BGP)is inter-autonomous system (71)protoc01．BGP is based on a routing method called path vector routing

Border Gateway Protocol(BGP)is inter-autonomous system (71)protoc01．BGP is based on a routing method called path vector routing

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问题 Border Gateway Protocol(BGP)is inter-autonomous system  (71)protoc01．BGP is based on a routing method called path vector routing．Distance vector routing is not a good candidate for inter-autonomous system routing because there are occasions on which the route with the smallest  (72)  count is not the preferred route．For example，we may not want a packet through an autonomous system that is not secure even though it is shortest route．Also，distance vector routing is unstable due to the fact that the routers announce only the number of hop counts to the destination without defining the path that leads to that  (73)．A router that receives a distance vector advertisement packet may be fooled if the shortest path is actually calculated through the receiving router itself．Link  (74)  routing is also not a good candidate for inner—autonomous system routing because an internet is usually too big for this routing method To use link state routing for the whole internet would require each router to have a huge link state database．It would also take a long time for each router to calculate its routing  (75)  using the Dijkstra algorism．(201 1年上半年试题)
(75)
选项 A、table
B、state
C、metric
D、cost
答案A
解析 译文：边界网协议(BGP)是自治系统间的路由协议。BGP是基于路由的方法称为路径矢量路由。距离矢量路由是自己系统路由的很好的候选者，因为跨自治系统路由场合上最小的跳数的路由不一定是最合适的路由。例如，我们可能不希望通过一个自治系统不安全的数据包，即使它是最短的路线。此外，距离矢量路由是不稳定的，路由器只宣布到目的地的跳数，但指出到达目的地的路径。实际上，如果是通过接收路由器本身计算的最短路径，接收距离矢量通告报文的路由器可能被愚弄。链路状态路由在跨自治系统中也不是一个好的候选者，因为对于这种方法互联网是通常过大。要对整个互联网使用链接状态路由，就需要每个路由器有一个巨大的链路状态数据库。它也需要每个路由器用很长的时间来使用的Dijkstra算法计算自己的路由表。
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