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We currently have a switching topology in which two 7600 make up the core and there are N many access layer 4948s at the top of every few racks. They are trunked to both 7600s. I would like to migrate to a Nexus environment. My question is can Nexus series co-exist with 4948s?

From the documentation it seems as if it would be possible to create a vPC for each 4948 as in:

vPC1: 4948 rack 1 Te1/49 ---> Nexus1, 4948 rack 1 Te1/50 ---> Nexus2
vPC2: 4948 rack 2 Te1/49 ---> Nexus1, 4948 rack 2 Te1/50 ---> Nexus2
vPCN: 4948 rack N Te1/49 ---> Nexus1, 4948 rack N Te1/50 ---> Nexus2

The current setup obviously leaves one of the Te's blocked by STP. Is that true (if this is possible) that the 4948s would utilize both Te interfaces since vPCs are non blocking?

Is this a viable setup?

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Yes that will work, Nexus switches have a feature called vPC (virtual port channel) that allows two up-links from the same switch to terminate on different Nexus switches but be configured into a single port channel so STP does not block one of the links. You can find more information here:

The Nexus is a high performance L3 switch so there is no reason why your 4948s cannot co-exist with it.

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They co-exist at L2. What would happen if I replace one of the 7600s with a Nexus. Will it the Nexus still play by the rules at l2 and use spanning-tree? – random3458sfd Mar 21 '13 at 19:44
Yep. They'll do that quite happily. You might check this document out:… – scottm32768 Mar 21 '13 at 19:56

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