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Intra-VLAN multicast traffic on Nexus 7000

November 11th, 2014

I have couples of 3750 and Nexus 5K connected to 2 Nexus 7010. The N7Ks run in VPC mode. I have a Multicast source and multiple multicast receivers, they are on the same VLAN. This VLAN is only a Layer 2 VLAN.

The issue is, only the receivers that are on the same access switch with the source receive the traffic. If the receivers are on difference access switch, they don’t see the IGMP Join Group packet.

A bit of digging around, I found out the reason, is that the other switches does not have an mrouter port and does not know about the source.

There are 3 solutions to fix the issue:
1. Turn on an SVI interface and enable PIM
3. Turn off IGMP snooping on ALL switches.

Let’s focus on solution #2. Since I don’t need to route the multicast traffic outside of the VLAN, this is the best solution:

To do this on the Nexus 7000 you need to do the following:

Where x.x.x.x is an un-used IP address
And you need to run these command on both VPC switches

For more information, have a look at this article

Categories: Data Center, Networking