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Next: Coding and Compression Up: Multicast Previous: Calling down traffic on


In this chapter we have looked at multi-destination packet delivery services, for circuit, and packet, and packet over circuit based networks. We have looked at the various routing systems that are used to devise delivery trees over which multimedia data can be sent for the purposes of group communication.

The main lessons are that:

If you have group communication, network support through multicast will in general reduce traffic significantly.
The IP multicast model is very powerful, and is much more convenient than the point-multipoint VC services in other networks. It is however hard to implement the former over the latter, efficiently.
Large scale use of multicast may require some form of aggregation of IP level multicast tree indices (state in Mbone routers) - we do not know how to do this at all.
Policy and QoS support in multicast routing are not yet available technologies.

In the next chapter, we will look at how to reduce the amount of data that is sent so that it doesn't swamp our network.