Why MSDP?

["Nagesh Chintada" <nagesh.chintada@alcatel.com>]

Greetings,

I have a very basic question:

First, the context:
For inter-domain Multicasting, one would typically deploy
PIM-SM/MBGP/MSDP protocols.....
MBGP for announcing  routes that include subnets containing multicast
sources, and MSDP
to announce sources.

Since MBGP already has the capability to announce multicast routes, why
not announce host routes of multicast sources as well, using MBGP? If
necessary, one can think of a simple extension to MBGP to mark the host
route as a "source route". IMHO, this will make it much easier to deploy
Multicast without having to worry about delpoying MSDP.

Any comments?

Best Regards,
Nagesh