troubleshooting WLC upgradr

[ragnar21]

So, I'm pretty green. 5 or 6 years in and learning on the job please bare with me.

tldr: is there a way to upgrade wlc software without all APs going down.

I'm looking to upgrade ios/software on my wlc. I have 2 in ha. And 3 sites, each with 2.

Each site has the same ssid with different vlans.

When I upgrade the software I have to go through change control and request downtime to wireless devices for the entire sight. It's a hard ask. 80% of the site is 24/7 and more and more devices and wireless.

The only way I can think of to avoid mass downtime, is to install 2 new wlcs upgrade them, and move the aps one at a time. I'm hoping for a less costly way

[Scott Fella]

What I can say is that with the 9800’s you can define a percentage of AP’s that will upgrade at a time. This allows for certain AP’s to upgrade while surrounding AP’s provide coverage.

With AireOS, you don’t have that option. If you have Prime Infrastructure, there is an option for rolling upgrades but it depends on your setup.

With HA, you are very limited but if you have a spare or running N+1, you can at least move certain AP’s to the upgraded controller instead of all at once. No matter what, you always should define a change window just in case you run into issues. That will save your behind.

[Rich R]

As long as you pre-download the software to the APs the down-time is minimised but that depends on specific AP model as some of them don't have enough space for 2 images on flash and some (like 3700) do the double download (see previous posts where @Leo Laohoo explains the process for avoiding that by downloading the image manually).

ANY network needs some regular change windows agreed for possible downtime - that is unavoidable to keep things up to date and properly maintained.  As Scott says you could minimise downtime with N+1 WLCs.  Upgrading to 9800 with advanced license allows ISSU and upgrading APs a certain % at a time but if the site only has 2 APs then that still means 1 AP at a time so you will lose 50% of coverage.  Note there are lots of caveats to using ISSU.