All things related to multicast

[Bill Nickless <>]

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>On Wed, 4 Apr 2001, Doron Rajwan wrote:
>
> > Good work!

Thanks--I really do appreciate you taking the time to read and comment.

> > I would add that in current multicast service model a source cannot know
>if
> > it has listeners or not. This is needed, because it will allow to
>implement
> > sources that advertise, say, all the radio stations in the world, but,
> > transmitting each station only when there are receivers. Such a protocol
> > will save bandwidth from the server to the first hop router, and more
> > important, computing resources inside the server itself.

There is one situation where a network device is explicitly asked for 
traffic from a source on a specific group: a PIM-SM (S,G) join.

An interesting experiment would be to implement a multicast media server 
that "speaks" PIM-SM just enough to accept (S,G) joins.  Upon receipt of a 
specific (S,G) join the media server could crank up the requested 
transmission.

This would let the media server know whether there were ANY receivers 
listening.  It would not let the media server know if there were any more 
than one receiver listening.  It would also not work for receivers on the 
same subnet as the media server, because IGMP would not be involved.

This would be easiest to implement in the SSM service model, but with the 
addition of the media server speaking MSDP it could be used in the ASM 
service model as well.

===
Bill Nickless    http://www.mcs.anl.gov/people/nickless      +1 630 252 7390
PGP:0E 0F 16 80 C5 B1 69 52 E1 44 1A A5 0E 1B 74 F7     


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