Behavior / Impact Upgrading N5K to FEX (reboot?)

[mjauner]

Good Day

I am wondering how the behavior is if upgrading Nexus 5500 with connected FEX.

The setup is:

2 Nexus 5596  (vpc roles primary/secondary)

Many FEX 2248 / 2232 connected to the 5596. Every FEX with one link to the primary and one link to the secondary.

- Is it fact that after I will do a SW Upgrade on 5596 all the FEX will reboot after receiving the new image ?

- Will this occur a second time after SW upgrading the 2nd 5596 ?

- What's the behavior if the 2 5596 do not run same version (while upgrading it will be so for a moment, maybe this could stay a longer time) ?

If 1) is true, so all the redundant design is useless while upgrading...

Thanks for answer

[eric.long]

The upgrade behavior for dual homed FEX is described in the upgrade guide below.  If you follow the process in the guide the FEX will be rebooted once, after the primary switch is successfully upgraded.  You initiate the FEX reboot when you are ready. 

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/upgrade/521_N1_1/n5k_upgrade_downgrade_521.html#wp641802

Depending on your topology and your current version you may be able to do an ISSU rather than the disruptive upgrade, the prerequisites are listed in the document.  You can also test whether you can do an ISSU with the "show install all impact" command.  The command will tell you what the impact of your upgrade will be before you do it, and will verify what components need to be upgraded. 

As to your third question, yes the two switches can run a different NX-OS during the upgrade.  But you should always review the release notes for your new version just to double check compatibility between your specific releases.