All things related to multicast

[John Zwiebel <>]

On Monday, May 13, 2002, at 06:45 PM, Marshall Eubanks wrote:


> P.S. We want to start sourcing SSM video soon. A query - which would be 
> better:
> to declare part of our GLOP space to be SSM, or to use the SSM address 
> range ?
> Which would be easier to use mim with ?

Neither.

Just include the source in the SAP for your sessions so that
an SSM aware application can issue an IGMPv3 request if it
is able.  That way you can support ASM and SSM with the
same source.

The downside will be that if folks join your session, and the
session has no data, then the tree will be brought up and
torn down repeatedly.

In the SSM range (or if the  router is configured for some
other range) PIM joins will setup and maintain state.

As far as the routers in the internet are concerned, there
is nothing different about receiving a PIM (S,G) join for
an SSM group or ASM group, its only behavior difference
is that data is what keeps an ASM SPT up, while PIM control
messages keep an SSM SPT up.


Ross Finlayson sent me the following.
-------------------------
It turns out this same question came up on the "mmusic" and 
"ssm-interest" mailing lists earlier this week.

There used to be an Internet Draft - "draft-ietf-mmusic-sdp-
srcfilter-00.txt" - that described how to (among other things) describe 
SSM sessions in SDP - e.g.,
        c=IN IP4 232.3.4.5/127
        a=incl:IN IP4 232.3.4.5 192.168.9.10

I.e., in this example, the session uses the SSM address (232.3.4.5, 
32.3.4.5)

It turns out that this draft has now expired, so the "mmusic" working 
group will probably resurrect it so that this can proceed on the 
standards track.  However, this approach seems to represent the 
consensus of the working group.

I hope things are going well at Procket.