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Cat 6500 2T and Nexus 5000 Multicast forward lookup

ROBERT BROOKS
Beginner
Beginner

Hello,

I have a quick question before I log a TAC case on this with Cisco.

We have a Core 6500 in a VSS configuration running Sup2T with 15.0sy code.  We also have some Nexus 5596 in L2 only running 5.2 Code.  We are playing with Microsoft NLB and I am aware of the different requirements for static MACs and ARPs depending on the mode you use.

My question is regarding the 2T and Nexus Multicast default lookup mode.  I have read that this has changed from the old DMAC address lookup to a new default behaviour of IP address lookup.  That's fine - but it trips up on Microsoft NLB if you want to take advantage of the Multicast IGMP mode as the switch learns of the Multicast MAC but it is never used as the forwarding mode is looking for the 239.x.x.x address that is never seen.  You still end up having to put in the static MAC table entries.

How do I change the Multicast L2 lookup modes on Nexus 5K and  6500 2T back to DMAC ( accepting the 32:1 overlap issue that it was changed for ) ?

Perhaps you can't !

Regards

Robert

1 Reply 1

Hi Robert,

We are having the same NLB problems with Nexus 5000. Did you get wiser after your TAC case?

regards,

Wim

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