[c-nsp] SSM Multicast backwards compatibility with an ASM core: What is the definition of "last hop router"?

[Phil Mayers]

On 04/09/2010 10:12 PM, P C wrote:
> I have a need to run Source Specific Multicast (PIM-SSM) over a network
> which otherwise only supports Any Source Multicast (PIM-SM).
>
> I understand it's only required that the "last hop router" actually be SSM
> aware.  What's unclear to me however is what the last hop router means.

The one speaking IGMP to receivers.

> Does this mean, given the diagram below only the router closest to the
> receiver<Router 1>  would need to understand a (S,G) join directly from the
> host and everyone in the middle wouldn't care -

Correct. The (s,g) joins are identical to ordinary PIM (s,g) joins, and 
are processed normally.

Having said that, I've never tested this ;o)