All things related to multicast

[David Meyer <>]

> >I think there are probably MSDP issues I am over looking here 
> >since MSDP doesn't have communities like MBGP, but I don't 
> >think they are a major problem.
> 
> Filtering MSDP causes black holes -- but since MSDP uses MBGP routes
> to decide the path that SA's will travel, it will respect your MBGP
> policy.
> 

        Yep.

        From draft-ietf-msdp-spec-05.txt

10. SA Filtering and Policy

   As the number of (S,G) pairs increases in the Internet, an RP may
   want to filter which sources it describes in SA messages. Also,
   filtering may be used as a matter of policy which at the same time
   can reduce state. Only the RP co-located in the same domain as the
   source can restrict SA messages. Note, however, that MSDP peers in
   transit domains should not filter SA messages or the flood-and-join
   model can not guarantee that sources will be known throughout the
   Internet (i.e., SA filtering by transit domains can cause undesired
   lack of connectivity). In general, policy should be expressed using
   MBGP [RFC2283]. This will cause MSDP messages will flow in the
   desired direction and peer-RPF fail otherwise. An exception occurs at
   an administrative scope [RFC2365] boundary. In particular, a SA
   message for a (S,G) MUST NOT be sent to peers which are on the other
   side of an administrative scope boundary for G.