ACI APIC upgrade and leaf/spine upgrade with three weeks in between

[laurent.dewilde]

We'd like to upgrade our ACI fabric from 4.2(6d) towards 5.2(3e).

The plan is to upgrade the APIC controllers very soon, but only upgrading the leaf/spines after New Year.

Is it an issue to upgrade the APIC controllers first and the leaf/spines more than three weeks after?

Thanks!

[kristjankristinsson]

The reason why you should try to upgrade them as soon as possible after is if you are pushing new configuration (or features) which the old software wouldn't understand. For minor releases this is not generally an issue, had several customers that have done exactly what you proposed even with major, so you'll likely not have any issues unless you change the configuration, but that said I don't think it's the recommended approach.

[laurent.dewilde]

Thanks for your reply Kristjan. But when making policy changes on policies not impacted by the new software release, no issue should arise, right?

Would provisioning new leafs onto the fabric be an issue with the APICs and leafs running on different versions?

[Sergiu.Daniluk · Accepted solution]

Hi @laurent.dewilde 

"But when making policy changes on policies not impacted by the new software release, no issue should arise, right?" -> There can be impact especially if default value for some object attributes changed between versions.

"Would provisioning new leafs onto the fabric be an issue with the APICs and leafs running on different versions?" -> Unexpected behavior can be present if different versions are running.

If there are plans to perform config changes or leaf/spine provisioning simply do not upgrade the APICs.

Stay safe,

Sergiu

[laurent.dewilde]

Thanks for your reply, Sergiu!

Clear!

[RedNectar]

Hi @laurent.dewilde ,

For an example of what can go wrong see https://rednectar.net/2020/09/05/aci-version-mismatch-alert-dont-use-v5-on-apic-and-v14-on-leaves/

Disclaimer: The link above is to MY personal website and is included as an informational service only.