[c-nsp] Multicast RP's

[Phil Mayers]

On 22/02/11 13:16, Aaron Riemer wrote:
> Hey guys,
>
>
>
> Quick question on something I am having trouble finding documentation on.
>
>
>
> Does anyone know how a configured RP in a PIM SM implementation become aware
> of all multicast groups within a particular network? Are they advertised via
> PIM running on each PIM via the multicast routing table?

If I understand what you're asking, then no - RPs don't know about 
"groups" in that way.

For a new multicast sender, the PIM DR on the sender vlan sends a PIM 
register to the RP. The RP then performs an (s,g) join for the new 
source, and and sends a register-stop telling the PIM DR to cease.

Multicast receiver state is propagated by PIM join packets.

In other words, the RP "knows" about a group when someone joins it or 
sends to it.