All things related to multicast

[Bill Fenner <>]

>How does an RP know that a "sender" has left the group; joins and leaves
>are reciever initated?  Is an RP keeping a Source Active aging timer?

The RP's forwarding table entry for the source will time out due to lack
of packets.  (Of course, this means that in a domain running MSDP, RP's
should not send Register-Stop or prune back the source-specific tree,
in case there are group members in other domains!  This is another
interesting change to the PIM-SM semantics that I don't think anyone
has thought of yet.)

>Second question.  How long do msdp sa-cache routers cache SA information?

For N seconds.  The value of N can be found by querying msdpCacheLifetime
in the DRAFT-MSDP-MIB (except that nobody implements it yet so there's no
way to determine N except by experimenting or asking).

  Bill