Upgrading 4500X in VSS

[martino-cisco]

Hi All,

I can't seem to find Cisco documentation that covers IOS upgrade on 4500X without ISSU. ISSU is not an option for me as the version i'm moving to (03.06.05) doesn't appear to support ISSU.

Is there an alternative way to upgrade the 4500X in VSS without downtime?

[brselzer]

Hello,

What version are you upgrading from? You could try doing step upgrades. This means you would have to do a couple upgrades in order to get to where you need to go but if you can ISSU each one, you could still achieve no downtime. 

There is no other way to upgrade without downtime. If you can't do ISSU, you would have to change the boot statements and reload. Your other option is to upgrade one, let it come into standby cold and upgrade the other. This will still cause some downtime but it will be less than a full power cycle.