Multicast is flooding our switches despite IGMP snooping being enabled

We're using MS Network Load Balancing for 2 groups of 2 Win2003 TS servers. Both groups are configured for L2 multicast (no multicast IP being used) with IGMP enabled. Both groups of servers are on the same VLAN and subnet as our other servers and users. It appears as though the multicast packets are flooding the network as I can be on the far side of the network and receive L2 multicasts intended for those servers.

MS's documentation states that multicast pruning (IGMP??) is not enough to keep the packets from flooding the networking, although I thought that was the whole point of IGMP snooping?

Our switches all support IGMP snooping and have it enabled, although no other configuration has been applied. I'm curious if I'm misunderstanding how IGMP snooping works? Can anyone provide some insight into how multicast is working in this scenario and why I'm not getting the expected result - multicast session joining by participating hosts?

Reply to
thecompnerd
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Well there's your mistake then.

Have a look at:

Catalyst Switches for Microsoft Network Load Balancing Configuration Example

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Maybe that will help.

Reply to
Martin Gallagher

ple

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I've consulted the document before, but still don't have the answers I was hoping for. Shouldn't IGMP keep the switch from flooding all switch ports? Otherwise, what's the point?

Back to the scenario... it appears as though the way we should go with this is to put the Cluster TS's in a VLAN according to Cisco?

and multicast destination MAC the Cisco device ignores this entry and proce= ss-switches each cluster-bound packets. In order to avoid this process >swi= tching, insert a static mac-address-table entry as given below in order to = switch cluster-bound packets in hardware.

I'm not familiar with what's going on in this command. Is it mapping the multicast address statically and associating it as part of VLAN

200 on ports 2,3, and 4? If so, will this same entry need to be applied to each switch trunk in order to keep the packet from being flooded out the client ports intended for the cluster?

Thanks.

Reply to
thecompnerd

Example

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Do you have one switch or several? If more than one switch and only one vlan you might also need to look at:

Multicast Does Not Work in the Same VLAN in Catalyst Switches

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If you have multiple switches, even if the MS boxes are sending IGMP membership reports for their bogus multicast group, the other switches won't see the IGMP.

Reply to
Martin Gallagher

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