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IGMP Snooping and PIM - Router sents multiple leave for same group.

ernie.louie
Level 1
Level 1

I have about 20-2950Catalyst Switches configured in my lab with a single router (2620) configured with PIM. My traffic on this particular VLAN is probably 90% Multicast traffic with about 40 Multicast groups. Two question:

1) the router (IOS 12.1(3r)T will send an IGMP leave message for a specific group, but the same leave message with the group is sent many times within a few milliseconds. I do not believe this should be happening, but then this is the first time I'm really lookiing at traces on IGMP. Is this normal?

2) the 2950 switches seem to behave oddly - I thought that by having Snooping and PIM running, that the switch that only knows about the membership group should respond to the IGMP leave message. In my network, it appears that every one of my switches respond to the leave

1 Reply 1

p.krane
Level 3
Level 3

The following link should answer your question over the second question. http://www.cisco.com/warp/public/473/22.html#snooping_ov

You may need to look on the Cisco website for possible IOS issues for the first question.