All things related to multicast

[Toerless Eckert <>]

> >     Does anyone have a good source of information requarding the 
> > deployment
> > of Multicast in enviroments where you have switches that only a portion
> > support CGMP, and the others support IGMP snooping, and get them to
> > interoperate.
> >     Is this an issue, or do I have nothing to be concerned about?
> >     Any pointers would be greatly appreciated.
> > 
> > Thanks,
> > -Roy
> > 
> 
> http://www.cisco.com/warp/public/732/Tech/multicast/

Don't we just love the easy memorizable URLs ;-))

> some pointers here.  I am currently having trouble with exactly such
> a combination which has led me down the road of trying to find where
> an mroute for a host I turned off three weeks ago is getting refreshed
> from (it shows as proxy joined on one router (flags CLX) and CLT, 
> registering
> on the local router....

Have you opened a case with the Cisco TAC on this ? I am not
aware of problems between IGMP Snooping and CGMP on Cisco switches.
If you do have non-Cisco switches with IGMP Snooping within the same LAN
with CGMP switches, you may have problem, because for CGMP to work correctly,
the CGMP-router must receive all IGMP-reports sent by hosts downstream
to a CGMP switch. An IGMP-Snooping switch may actually suppress IGMP 
reports for reasons of efficiency (only send those reports up to the router
that are necessary). Our IGMP Snooping switches actually do this optimization,
but stop to do it if they see CGMP in the network.

Cheers
------------------------------------------------------------------------------
Toerless Eckert                  cisco Systems Inc.
Software Engineer IP Multicast   125 Rio Robles (Building N)
IOS Network Protocols            San Jose, 95134 CA, USA
E-Mail:  

        Tel: +1 408 853 5856, FAX: +1 408 526 4952