End-to-End IP Multicast

End-to-End IP Multicast
Part of deploying multicast is the determination of how much of the network should be
multicast enabled. This is an important decision because it directly affects many aspects
of multicast implementation. To strategically place the RPs, you must know where all the
multicast leaf routers will be. Knowing the approximate number of potential multicast subscribers
can have an effect on which protocols are run in the network to allow efficient
multicast forwarding and routing.
The decision to use end-to-end deployment can be based on the applications that will be used
or the intent of the multicast implementation. If you are enabling multicast for a corporate
application, you would need to enable multicast on every interface on every router throughout
the enterprise. However, if you need to provide access to only the MBONE for the engineering
department, or some other department within the organization, perhaps the most efficient
method would not include end-to-end configuration and deployment.
It is important to keep in mind that the state of technology is dynamic. Today, you might
receive a request from a single department for multicast access. Before jumping on the project
and planning for just that department, consider that in the near future, it is likely that other
departments will also request access. Applications that require end-to-end multicast capability
might be purchased or integrated into the enterprise. It is far better to plan an end-to-end
deployment and initially activate only the routers and interfaces that are needed than to plan
your implementation on a limited initial activation. It is easier to “build it right the first time”
than to try to come back and work around or rebuild a poor IP multicast deployment.