Catalyst 4500X ISSU Upgrade Path

[brian.byrnes]

I'm in a situation that I need to upgrade a 4500X VSS switch using ISSU from 3.4.4SG Universal to 3.7.3E, both are running crypto images.  Is there a any sort of documentation, chart, time line, etc that show's the ISSU upgrade path that can be used to achieve this?

[Philip D'Ath]

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/15-1-2/XE_340/configuration/guide/config/vss.html#wp1322727

[Philip D'Ath]

ps. The "quick and easy" way is to use the " issu changeversion" command.

[brian.byrnes]

I'm looking for documentation on what the upgrade path should be not if it's a compatible ISSU

[brian.byrnes]

That's to process to invoke an ISSU upgrade, which I was previously aware.  I'm looking for the version I can use to perform an ISSU from X to Y, as Y is not a supported version for to perform an ISSU from X.

[Philip D'Ath · Accepted solution]

Yucky, it says you can't use ISSU for that upgrade.

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/XE3-6-0E/15-22E/configuration/guide/xe-360-config/issu_XE.html

• A permanent “ISSU barrier" exists between pre-IOS XE 3.6.0E and IOS XE 3.6.0 releases: ISSU is supported between versions on the same side of the barrier but it is not supported between versions on opposite sides.

[brian.byrnes]

That is what I was looking for, thanks!

[Philip D'Ath]

I think you are going to have to just copy the *.bin file to the local bootflash in each switch, change the boot environment variable, and reboot both at the same time (to stop vss having a heat attack).

[parkst125]

Just to verify , I am using an out of the box 4500 that's running 03.03.02.XO  and I am upgrading to 03.06.03.E.152-2.E3.bin .

So ISSU doesn't work on IOS older than 3.4 ?  So my out of the box 4500 can't do ISSU until I upgrade the code?

[Leo Laohoo]

I don't believe in the hype:  I've never had any successes with ISSU, FSU/eFSU.  

Just copy the IOS into the primary and secondary line cards, change the boot variable string and this should be fine. 

And, if possible, do not forget to upgrade the bootstrap. 

[parkst125]

This process works and I did use it because these are brand new chassis going into service and ive had issues with ISSU.  However, it would be nice to get ISSU working properly so code upgrades can be done in the future without taking down the network.