Upgrading 4.2(3l) to 4.2(7s) - APIC questions

[brlehigh]

I need to upgrade our production fabric from 4.2(3l) to 4.2(7s).  As part of the upgrade, it appears that my APICs require an CIMC/HUU update.   I have the following questions:

1. Are there any major issues with upgrading the APIC cluster on one day and then upgrading the leafs and spines on another? ( I don't anticipate and configuration changes to occur on the fabric between these two days.)
2. What is the recommended order of operations for the APIC software / HUU upgrade?  Should the CIMC/HUU upgrade be performed before upgrading the APIC to 4.2(7s), or vice-versa?

I've looked through the upgrade guides but couldn't find a definitive answer on either of these questions.

Thanks!

[Robert Burns]

1.  No issues.  You can make changes to your fabric fine, just obviously don't enable any new features (if any) only present in the new SW version until the entire fabric upgrade has been completed.

2. See: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/recommended-release/b_Recommended_Cisco_ACI_Releases.html

Robert

[brlehigh]

Thank you for the quick response.  So, no issue with upgrading the APICs and then waiting a day before upgrading the switches.  This is what I was hoping for, otherwise it makes for a really long maintenance window.

I'm not finding the answer for my second question in the link you provided.  The documents show recommended versions of HUU/CIMC for the desired APIC software release.  My question is:

Do I perform the HUU/CIMC upgrades on each APIC, and then upgrade the cluster to 4.2(7s)

or

Should I upgrade the APIC cluster to 4.2(7s) and then upgrade the HUU/CIMC on each APIC?

[Robert Burns · Accepted solution]

Personally, I always upgrade the IMC right after the APIC cluster is upgraded. The nice thing about this step is that you can do them with everything online and you do them one by one. I've heard others do the other order also, but as the HUU versions follow the APIC version, makes sense to me to do APIC first.

Robert