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MGStickler
Beginner

Does a (N7K) VPC Peer Link have to be twp (2) 10Gbps Ports

Is redundancy the only reason the VPC peer link between two N7Ks has to be a 2-port port channel? Do they have to be 10Gbps ports? What happens if only 1 physical port is used, but it is part of a port-channel?

Also, if both the VPC peer link and the peer keep alive go down, shouldn't the port channels within the VPC continue to forward? The physical ports and the port channel should remain up on one N7K if the second where to be powered down completely, correct?

Thanks! We saw some strange behavior when we tested an environment that I did not design or build.

2 REPLIES 2

No it does not have to 2x 10Gb interfaces. You can use 1 physical interface, but that must be part of a port-channel as the " vpc peer-link" is only available on a port-channel. That makes sense, later on when you want to add additional interfaces.

The question is would you want to use 1x 1Gb or 1x10Gb interfaces? For that consider what traffic in your network travese the Peer-link and ascertain  if the link size will suffice for the amount of traffic.

This traffic would include but is not limited to:

- VPC control and synchronizing traffic.

- Traffic to Orphan ports.

- in failure scenarios can the peer-link carry all relevant uplink traffic if it can only exist via the peer chassis?

- etc.

In a split brain scenario, when you loose both your peer-link and peer-keep-alive link, both systems will assume themselves as the only operational system, and will forward traffic. This should (and I say generally) not pose a problem for STP or data traffic. (i.e., all traffic received on a downlink port can only exit on an available uplink port). Both chassis will appear to other switches are one switch since they both will be sourcing traffic from the same virtual system VPC mac.

Alterntive have a read trhough the N5K design guide, and check out the VPC failure scenarios.

http://www.cisco.com/en/US/products/ps9670/products_implementation_design_guides_list.html

I hope I answered all you questions sufficiently

Yes, thank you very much!!!!!

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