Layer-2 multicast not forwarded through 5500G-EI

[ss370]

Hi,

Can someone please help me with this issue:

3Com 5500G-EI configured as layer-2 only does not forward multicast. Igmp-snooping does not report any groups.

The layer-3 multicast router and igmp querier is a Cisco router which is connected to the 3Com layer-2 switch.

However, if I do not use the Cisco router, and instead configure the 3Com 5500G-EI as layer-3 and let the 3Com do the igmp queries, multicast works. So the problem is clearly related to interoperability between Cisco layer-3 and 3Com layer-2.

Any ideas?

 

[engjohn]

have you tried disabling IGMP snooping on the 3Com switch?

 

[ss370]

I have done some more tests since my original posting.

It looks like I am running into trouble when using both vlan-vpn (Q-in-Q) and IGMP snooping at the same time.

I would like to run IGMP snooping on the service provider VLAN so that the traffic carried within the vlan-vpn can utilize multicast in an optimized way.

This config fails to forward multicast:
#
interface GigabitEthernet1/0/25
stp disable
broadcast-suppression pps 3000
port access vlan 12
vlan-vpn enable
#
vlan-vpn tunnel


This config succeeds in forwarding multicast,
but the IGMP snooping feature cannot be used:
#
interface GigabitEthernet1/0/25
stp disable
broadcast-suppression pps 3000
port access vlan 12
vlan-vpn enable
igmp transparent enable
#
vlan-vpn tunnel


Any ideas on how to get both Q-in-Q and IGMP snooping to work together?