Re: Use of SAP in a PIM SSM Network

[Leonard Giuliano <lenny@juniper.net>]

I suppose one way to make SAP work in SSM is to modify the protocol to
have the directly connected routers to active sources use unicast to
register with core "rendezvous points".  Then each of these rendezvous
points will talk to each other with another protocol to tell each other
about the active sources that they are each aware of.  Wait, this sounds
familiar...

SSM presents an interesing tradeoff where some functionality is reduced to
meet a much more common model as well as radically simplifying network
deployment.  Being only able to join a single source is inherantly
incompatible with something like SAP, but few commercial content providers
would disagree that sdr doesn't represent the commercially viable future
of multicast.  SSM hinges upon the mass appeal of one-to-many apps like
WMP, Real player and IP/TV, while eliminating the biggest hinderance to
deployment: a PIM-SM/MSDP RP-based infrastructure is too complex.

Maybe SSM is just a stepping stone to the full functionality that
shared-tree infrastructures provide.  But it will be a whole lot better
than what we have now, where multicast is virtually nowhere to be found.