How to upgrade Cisco’s WLC AireOS software

Quick n’ easy and just to complement my last post on updating a WLC’s FUS, here’s a guide on how to upgrade Cisco’s WLC AireOS software. Do we still call it AireOS? I guess, but for those of you just joining the networking world and referring to this piece of software as “WLC controller software”, the name “AireOS” goes back to 2005 when Cisco acquired the prominent wireless company Airespace from which it inherited the “Wireless LAN Controllers”. Basically, WLCs are -yet another product- that Cisco rebranded and later improved, you can still find some Cisco Aironet controllers on eBay, in case you want to start your own networking history museum.

Anyway and going back to business, after I upgrade the FUS on my WLC I’m ready to upgrade from AireOS to so the controller can register my Cisco 1602i AP.

1 Go to and download the AireOS version you need. in my case. Protip – Do always check your MD5/SHA512 hashes! file integrity is first.

2 Login to your controller and go to  Downloads/Download file to the controller . Check “Code” in the drill down menu, your preferred transfer mode (for me tftp it is) and set your server details. I’ve seen mixed results from people doing it different ways but, I do always add a  “/”  at path so the image file goes to the root of the system. Click the  Download  button to start the transfer.

3 You will see the status of the process at the bottom and once it’s done you will be prompted to reboot the controller. Before rebooting you can manually upgrade the image running in your APs to save time but unless you have a huge deployment or mission-critical APs, the saved amount of time is marginal. Go to  Commands/System Reboot  and hit the  “Save and Reboot”  button.

4 Once the AP is back, crosscheck the running image at the home dashboard.

5 If everything went alright, you should be seeing the APs joining the controller at  Wireless/All APs . Since i didn’t pre-download the new image on my AP, the first step for it after joining is to upgrade to the correct image. If this happens you will see Downloading on the Operational Status column.

6 When the AP upgrade finishes it will reboot once and register with the correct image. You should now see Reg on the Operational Status colum.

You are all set, after this process your APs should start broadcasting back the configured SSIDs (if any). In case you wonder, i used the ol-reliable tftp64 for this upgrade as well.

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