OS upgrade traditional way ie cold restart nexus 7010

[kmothukuri]

Hi All , N7K1  - VPC - N7K2.Both switches are running 6.2.2a currently. Each 7k has dual sup 2E modules . I am planning to upgrade them to 6.2.20with cold restart procedure. I would like to know whether vpc peer link goes down or not when N7K1 comes online with newer code ie 6.2.20. Does mismatch of OS versions of N7Ks will break vpc peer-link ? before reloading N7K2 with newer code .  n7k1 with 6.2.20 and n7k2 is still with 6.2.2a .what happens to traffic flow and peer link .Down stream switches ie n5ks are dual homed to n7k over the fabric path.

[Brendan M · Accepted solution]

Howdy knothukuri,

To start, here is the documentation on carrying out a cold upgrade of a VPC:

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/nx-os/tech_note/vpc_upgrade.html#pgfId-51350

Answering each of your questions directly:

"Does mismatch of OS versions of N7Ks will break vpc peer-link?"

The upgrade process will bring down the peer-links/peer-keepalive-links during the cold upgrade. This link going down will cause a fail over to your secondary device (N7K2) during the upgrade of the primary device (N7K1). Impact should be minimal for port-channeled devices since you are in a VPC, but this should still be done during a maintenance window.

"what happens to traffic flow and peer link?"

As soon as the one of the VPC member switches (in your case N7Ks) goes down, traffic will begin being redirected to the member switch that is still active. This is the same as if you were using a traditional port channel (not VPC) and one of your links went down. More information on this can be found in this document (page 5):

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

Hope this helps!

Cheers,

Brendan M

[kmothukuri · Accepted solution]

Hi Brendan ,

Thank you for the valuable info.

We had OS upgrade on pair of nexus 7010 successfully with a maintenance window . After Loading newer Image we have done Cold restart and it took 20 minutes to come 7010 switch up with newer Image.

We had Primary flash issue on the second 7010 during the OS upgrade and luckily we had flash recovery loaded into both switches in advance.

Note : Whenever anybody is planning for OS upgrade on 7000 series switches , one has to make sure that both primary and Secondary flashes are working fine .If flash has issue then OS upgradation fails I mean switch will load with old image even though one has rebooted with newer image by chaning the boot variables to newer image.