4500x vss issu question

[RBrower]

We have two 4500x switches in a VSS configuration running as our core. Recently we started getting some parity errors when we enabled some monitoring/polling of switch statistics. Cisco Tac has instructed us to reboot the core to clear the problem. While we are at it TAC wants to upgrade to the latest (and supported IOS).

Here is my dilemma since it is our core it does all layer 3 routing for the DATA Center our server team is unwilling/unable to shut down and give me a safe maintenance window that would not disrupt operations. Even moving layer 3 to another device is potentially disruptive and not an option not to mention I don't have the ports available to make the connections. 

I've looked at the ISSU option but haven't seen anything that makes me comfortable that it will be successful. However, this might be my only option since I can't have an outage. 

Any suggestions? has anyone successfully done a ISSU? 

[Reza Sharifi]

Any suggestions? has anyone successfully done a ISSU? 

Honestly, with ISSU, you run the danger of more downtime than simply loading the new IOS to both primary and backup sups, changing your boot parameter, saving the config, and rebooting the set. Most of the time with ISSU, you end up rebooting more than needed. In addition, most of the upgrades don't even qualify for it. If you plan everything ahead of time, the 4500-x VSS takes about 10 min to reload completely. It is much faster than the 6500 and 6700 VSS.

HTH

[balaji.bandi]

i go with the traditional upgrade and easy way than more complicating ISSU upgrade :

https://zebust.wordpress.com/2019/04/10/c4500-x-vss-software-upgrade/

Make sure read the release notes before upgrade, offload the config always to be safe. take more downtime for extra precations in case to fix the issue.

[Leo Laohoo · Accepted solution]

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@RBrower wrote:

has anyone successfully done a ISSU? 

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If the pair is vital, do not take any unnecessary risk -- Do not make any attempt to use FSU/eFSU or ISSU.  I wholeheartedly agree with @Reza Sharifi and I do not recommend upgrading using FSU/eFSU or ISSU.  PERIOD.  

Please have a look at my previous response about how to upgrade the 4500X VSS firmware (LINK).