Clos网络中的组播路由算法

对于三级Clos网络，扇出机制会影响Clos网络的阻塞率、算法的时间复杂度及网络成本，因此选择好的扇出方式能充分发挥网络的组播能力。根据输出级扇出、中间级扇出、输入级扇出等不同的扇出机制分类，可将组播算法分为输入级扇出算法（IFMA）、最迟扇出算法（LFMA）、切割扇出算法（SFMA）、中间级优先扇出算法（CMFF—MA）。在对4种算法仿真比较的基础上，文章提出针对不同的业务采用不同的处理方法的路由方案，对于固定扇出业务可采用CMFFMA算法进行路由，针对递增业务采用先输出级、再中间级、最后输入级扇出的策略，可有效地降低阻塞率。

The Analysis of Multicast Routing Algorithm in Clos Networks

Fan-out mechanism would affect the blocking probability of the three-stage Clos network, the time complexity of the algorithm and network costs. Good fan-out approach can give full play to the multicast capacity of the network. According to the output-stage fan-out, middle-stage fan-out, and input-stage fan-out mechanisms, multicast algorithms include Input Fan-out Multicast Algorithm (IFMA), Lazy Fan-out Multicast Algorithm (LFMA), Split Fan-out Multicast Algorithm (SFMA), and Central Module First Fan-out Multicast Algorithm (CMFFMA). Comparing the analyses of these four algorithms, this article proposes a routing scheme in which different businesses use different algorithms. Bundled traffic can adopt CMFFMA, and incremental traffic can route from output-stage through middle-stage to input-stage fan-out. Therefore, the blocking probability can be effectively reduced.