在IP网络中,当某链路或者节点发生故障时,通过路由协议的收敛来绕开故障的链路或节点.对OSPF路由协议,这个时间至少为5秒,期间经过故障节点或链路的流量将会被丢弃,绝大多数的应用可以承受这种程度的延迟.但是,对延迟敏感的应用如VoIP而言,这种量级的延迟是很难为用户所接受的.基于现有的OSPF路由协议的最短路径树(SPT)算法,提出一种支持IP快速重路由的多冗余路径树计算算法.算法计算除最短路径外至少一条不相交无环备份路径,保证在最短路径的链路或节点故障时,通过快速切换到备份路径,以提高IP网络的故障收敛时间.%In the IP network,bypass the failed link or node through the convergence of routing protocol when a link or node failed. This time at least 5 seconds for OSPF routing protocol,during the fault the packet will be dropped,most of the applications can accept this level of delay. However, delay-sensitive applications such as VolP, the delay of this magnitude is difficult to accept for users. Based on the existing routing protocols of shortest path tree (SPT) algorithm, proposed to support multiple redundant path tree calculation algorithm for IP fast reroute. In addition to calculating the shortest path,the algorithm calculates at least one disjoint acyclic backup path, when link or node of the shortest path fail, ensure that the packet switchs to the backup path quickly to improve IP network fault convergence time.
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