DComTalk.com

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

Ned,

Ned wrote:
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

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