IGMP snooping in Fabricpath

[Josef Baloun]

Hello,

customer has 4 x Nexus 5500 (leaf) and 2 x Nexus 7000 (spine) running Fabripath.

Is it possible to turn off IGMP Snooping per vlan?

Does it have limitations/restriction?

Customer turned off IGMP Snooping in specific vlan on all switches in the domain.

When Nexus 5500 boots up it is writing this messages:

%FWM-2-FWM_IGMP_SNOOP_DISABLE_FABRIC_VLAN: IGMP Snooping enable/disable should be done on all switches in fabricpath cloud. Failure to do so may result in unexpected traffic behavior

Is it ok, or should we do another reconfiguration or so?

Best regards,

Josef

[Manish Gogna]

Hi Josef,

This IGMP Snooping log message is normally seen when IGMP Snooping is disabled/enabled, and is an informational message that raises your attention that all switches in the Fabricpath cloud should have the same IGMP Snooping configuration for FP VLANs.

HTH

Manish

[danailpetrov]

Hi Manish,

Is there any document supporting that statement? 

I completely understand why are you saying this (unifying IGMP config per VLAN on all LEAF devices) considering the fact of how the FabricPath works and the building of mroute table using GM-LSPs, but I couldn't find that anywhere on any FabricPath or best practice document suggesting it. Is there anything I have missed? 

Many thanks in advance!

[danailpetrov]

Hi guys, it's me again..

I am trying to figure out what'll happen if we have don't have the IGMP snooping enabled on ALL Leaf switches where the VLAN is present for the same topology. Am I right assuming that if we have VLAN10 enabled with IGMP snooping on leaf 1 and leaf 2 for instance, but not on leaf 3, then what will happen is that:

• The GM-LSPs will generate IGMP membership in Multi-destination topology 2 and thus receivers in VLAN10 will get the traffic delivered.
• If we have another host on leaf 3 joining, then due to the "no igmp snooping" there, the GM-LSPs will not add this leaf/host port to the IGMP membership (topology tree 2) and the traffic will be handled by multi-destination topology tree 1.

And here is my question - will that work? If we have traffic for group 239.0.0.10 for which hosts on leaf 1 and leaf 2 subscribed & there is GM-LSPs but host on Leaf3 is using multi-destination topology tree 1?

I am unable to verify this so any thoughts will be more than welcome!