All things related to multicast

[David Richardson <>]

> PIM-SM SNOOPING/SPOOFING ETHERNET SWITCH
> ========================================
> Consider a Gigabit/10-Gigabit Ethernet switch that is PIM aware.  It could
> set up appropriate hardware forwarding based on the PIM Joins sent between
> pairs.  Note that the hardware forwarding would have to maintain separate
> (S,G) packet replication states for each peer that has been asked for data
> by some other peer.  That is, the exchange point switch won't get to pick
> an RPF towards each (S,G), so it will have to maintain separate
> (S,G,RPF-port) states with distinct output interface lists.
>
> Benefits:  - Peers get traffic only for (S,G)s they care about
>             - Peers send only one copy of traffic for (S,G)s and
>               the exchange point does the packet replication.
>             - Peers get to choose (by their own policy) the best
>               RPF for a given (S,G).
>
> Drawbacks: - Not yet available in the marketplace (to my knowledge).
>

Foundry implements a PIM-SM snooping feature in their switches. We are
evaluating this for deployment in the SNNAP/PNWGP and plan to use it to
support multicast between peers.

 - David

Network Engineering
Pacific/Northwest Gigapop
University of Washington