Nexus vPC and vPC peer link

[michelegarribba]

Hi all,

i need some clarification about vPC. I'd like to know if the vPC peer link can be done of only one physical link between the 2 peers.

Is it mandatory that the vpc peer link is mad of a portchannel? Or can i setup the vPC domain with a vPC peer link made of one link and afterwards add a second physical link?

Thanks a lot

smaikol

[sachintambat]

Hi,

Cisco recommends that you should configure port channels that have at least two physical 10 Gigabit-Ethernet ports as the vPC peer link.

http://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/sw/design/vpc_design/vpc_best_practices_design_guide.pdf

[michelegarribba]

Hi sachintambat,

i know the raccomandation, i woudl like to know if the vpc peer link will work if, for a short period, the link is done by only one physical link, like i have configured a port channel but one of the link is down

thanks for your reply,

smaikol

[sachintambat · Accepted solution]

Yes it will work on one link also.

-Sachin

[sachintambat]

Hi smaikol,

I hope this works for you.

-Sachin Tambat

[michelegarribba]

Hi Sachin,

i'm at a design level now, but sure it ll be good for me now, thanks.

smaikol

[will]

as others have said, it is possible to do this with a single link. I don't believe you need a port-channel either. but there are scenarios where the peer link being down could case a split brain scenario, where traffic wont be able to get to where it needs to go.

if you are running extremely critical traffic or storage, I would recommend at least 2 links. I think that is cisco's reasoning as well. at the very least, make it a port-channel with one link so you can move cables around in the future by adding in another physical link to the port-channel.

BTW... you can run a pair of nexus 5k with the peer keep alive link (not the peer link) down, but just don't reboot them that way or they wont sync and possible you will deny traffic flows.

[jay.consultant]

Can it be done on a one gig port instead of a 10 gig port?

I have a 7K pair with little to no traffic and need the 10 Gb card that the peerlink is currently running over.

The 7K pair runs software version 6.2(16)

Thank you for your time