WLC-redundancy

[Irshad Mohammed Hussain]

Guys

I have 3 WLC Controllers at three different locations as shown below  and all of them are having HA, can I make some federation or any redundancy with this, in case if one site WLC fail AP's at that will register to other locations?

WLC 5520

Software Version

8.2.100.0

WLC 5508

Software Version

8.0.121.0

WLC 5520

Software Version

8.2.110.0

[Leo Laohoo]

Read THIS.

[Irshad Mohammed Hussain]

All the mentions WLC's are having different Versions , what will be the behavior of AP's when they  move across?

[Leo Laohoo]

The controllers all have different firmware versions.  So when the APs move back and forth between different controllers the APs will be forced to download the appropriate firmware.  During that time the APs will NOT be servicing any wireless clients.  

This is the reason why we DO NOT recommend controllers running different firmware versions.  It's just dumb.

[Irshad Mohammed Hussain]

As all controllers are in HA ,do I need to upgrade code for both WLC's in HA or only Primary ?

[George Stefanick]

I assume you are not in HA SSO mode and you are just doing high availability. 

Problem is one one an ap joins a wlc with a different code it will upgrade or down grade and reboot. Not good practice. Your primary and backup should always be on the same rev. 

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[Irshad Mohammed Hussain]

Yes all my WLC's are in HA SSO

[Leo Laohoo]

do I need to upgrade code for both WLC's in HA or only Primary ?

It's not a question of "do I need to".  

There are legitimate reasons why the controllers are running different firmware.  If one of the key objective is to ensure the APs have minimal impact during fail-over (from one controller to another), then yes, it makes common and logical sense to ensure all the controllers share the same configuration & firmware version.  

George (below) runs and manages wireless for health care environment.  Common sense dictates the APs need to operate with minimal disruptions necessary.  

On the other hand, I manage wireless of a different arena and I don't necessarily have to have my controllers running the same firmware version because I don't have that kind of "mandate".  However, I chose to run the same firmware to make troubleshooting easier.