Need a Querier for IGMP Snooping

Nov 11, 2005 2 Replies
N

I've read alot about IGMP snooping but I'm still not sure if the device creating the multicast traffic has to have some sort of IGMP snooping feature. I think the answer is no and that it is all handled by the network switch and routers. Can someone confirm this?



Also, I put a packet sniffer (Ethereal) on my switch and created multicast traffic on the other end of the Wan. I could see the traffic on my switch even though IGMP Snooping was configured. I have 3Com switches and Marconi switches and router on the ATM Wan. Any suggestions? Can I build my own IGMP Querier??



Thanks NH


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M

Ned, Be aware that if you do not have a receiver on a switch, but you have a source, the multicast traffic may get flooded to all ports. Snooping relies on seeing IGMP membership queries from hosts to make decisions on which ports to prune and graft. If there are no receivers on the switch, there might not be any membership queries (depending on the operation of the source), so the switch would flood. Nortel has implemented features that control multicast flooding when there is no registered receiver on a switch. I am not sure what other vendors have out there. Iperf is a really easy tool to use in multicast mode. We use it to verify multicast all the time. Not sure if this will help or not...

-mike

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