Hello!
I have a question regarding SSO failover on Cisco 4500 switches and stateful IGMP snooping. According to Cisco documents, IGMP snooping tables should be synced between the supervisors. At least this is how I understand "stateful IGMP snooping". So after the switchover the new active SUP should already know multicast groups and interfaces, and immediately forward multicast traffic.
I did some testing and see a different behaviour. Right after the switchover, "show ip igmp snooping groups" has no entries, and the switch sends an IGMP query. Then multicast receivers respond with joins, the table is populated, and the switch forwards multicast.
This causes problems for the particular application I'm working with (industrial protocol) because of very short timeouts. The devices are just slow to respond with joins. I expected at least to see flooding to all ports after the switchover.
My question: is there any configuration to enable stateful IGMP snooping, or multicast flooding after the switchover?
The switch configuration is no PIM, IGMP querier enabled on the VLAN. No multicast routing needed.
SUP 6E 12.2(53)SG4 and 15.0(2)SG
SUP 7E XE 3.1.1SG
I appreciate any help on this matter!
