Internet routing routing multicast routers interact

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Unformatted text preview: out neighboring routers. To avoid duplication of effort, a single router is selected (via IGMP) as the Designated Router for each physical network. network. Spanning Trees Spanning For efficient transmission, Designated For Routers construct a spanning tree that spanning connects all members of an IP Multicast group. group Minimal number of edges (transmission Minimal links) to guarantee delivery of source data packets to receivers packets Spanning Trees (continued) Spanning “Dense-mode” Multicasting The first approach is based on the assumption that The the multicast group members are densely distributed throughout the network and bandwidth is plentiful, is – i.e., almost all hosts on the network belong to the group. group. So-called “dense-mode” multicast routing So-called protocols rely on periodic flooding of the network with multicast traffic to set up and maintain the spanning tree. spanning “Sparse-mode” Multicasting The second approach to multicast routing is based The on the assumption that the multicast group members are sparsely distributed throughout the network and bandwidth is not necessarily widely available available – for example across many regions of the Internet Hence, ``sparse-mode'' multicast routing protocols Hence, must rely on more selective techniques to set up and maintain multicast trees. and Conclusion Conclusion IP Multicast enables many new types of IP applications and reduces network congestion and server loads. congestion Advances are being made in areas such as Advances reliable multicasting and real-time applications support....
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