IGMP Snooping on doubletagged traffic

[christopher.wood]

Hello,

I was approached to add IGMP snooping to some devices for traffic that is doubletagged through the network. I don't know what VLANs are being put into the doubletagged vlan. Customer having troubles with flooding of multicast to 4 locations.

I don't actually have anything to do with their multicast as all their traffic is doubletagged through the network. I just hand them a doubletagged port, which is the same doubletagged vlan at all their locations and they can put in whatever traffic they'd like. I don't think if I put IGMP snooping on the demarcation device it would help this customer. Seems like that is something they would need to do?

Just wanted to confirm if anyone knows for sure.

Thanks.

[paul driver]

Hello

Can you elaborate on your double tagging regards IGMP - Not sure i understand your query?

Igmp helps switch/routers learn what hosts need to receive MC traffic.

Snooping will control unwarranted flooding to switch ports within the vlans that don't need or not interested in receiving MC traffic and is usually enabled by default on switches.

res
Paul

[christopher.wood]

Hi Paul,

Sorry, I'll try to elaborate. I currently don't have IGMP enabled, nor does my equipment participate in any multicast queries, joins, sends, requests with the customer. 

I hand them a port where I only hand off one VLAN, which doubletags on top of their VLANs. I don't see their VLANs. The customer requested we turn on IGMP snooping to stop the flood of multicast traffic, but I don't see that traffic or their VLANs.

I'm thinking if I turn on IGMP snooping in this scenario, it will not benefit the customer as I have no control over the traffic they put into the VLAN I used to doubletag them through the network, other than I rate limited the doubletagged VLAN on my demarcation equipment and set a priority on it.

I hope that clears things up a bit.

Thanks.

[paul driver]

Hello

Sorry your term double tagging is something I relate too as something you would want to try and avoid occurring on the network not actually employing it.

This one port and vlan, What relation does it have to the customer and your network
Is this vlan used anywhere else on you network or is it a L2 transit connection between sites

If so I dont see any issue with you enabling snooping on this one vlan it wont harm your network.

res
Paul