Multicast Routing – A Brief Explanation
Multi-cast Routing is sending packets to a group of nodes only. So, creating and destroying groups, joining and leaving group primitives are to support multicasting. In multicast routing, each router computes a spanning tree per group which is created by removing all the links which do not lead to any routers of that group. This pruning can be done very easily in case of link state routing and reverse path forwarding can be used in case of distance vector routing.
Congestion Control for Multicast Routing
Managing multicast flows from multiple destinations is somewhat different from the single source to single destination flows. An example for multicast transmission is several television stations transmitting video streams to a group of receivers, each of whom can view one or more stations at once and the receiver is free to switch from one station to another according to his choice.
In multicast routing applications, groups can change membership dynamically. Hence the senders can’t reserve the bandwidth in advance.