[c-nsp] 6500 IGMP snooping database now bound to MAC address and not switchport?

[Sam Stickland]

On 9 Feb 2011, at 17:51, Phil Mayers <p.mayers at imperial.ac.uk> wrote:

> On 09/02/11 16:57, Sam Stickland wrote:
>> All,
>> 
>> I encountered some strange, but beneficial, behaviour in the lab. We
>> connected a server with teamed NICs to two 6500s running SXH2a. The
>> NIC teaming is active/standby using only a single MAC and IP address.
>> The server joins a multicast group and starts receiving traffic. We
>> found that if we pull the primary NIC everything, including the
>> multicast traffic, fails over to the standby NIC, losing a couple of
>> packets at most.
>> 
>> The strange thing is that packet captures don't show the server
>> re-issuing the IGMP join or sending any membership reports on the
>> standby NIC. In the past this would had resulted in a loss of
>> multicast traffic until the IGMP state is rebuilt on the new switch
>> port. But no longer.
> 
> Interesting. Have you tried monitoring a "debug ip igmp" and friends whilst this happens?
> 
No, not yet. I'll have to see if we still have all the equipment in the lab. I found this behaviour late last year but it's only now I have the time to follow it up.

San