As if I didn’t have enough wireless fun this past week… I recently stumbled across an issue trying to get a number of new Cisco 2702i APs to join a Cisco 5508 Wireless LAN Controller. I didn’t realize it at the time but the reseller had changed the part number on my order from AIR-CAP2702I-A-K9 to AIR-CAP2702I-B-K9. The significance is the new -B regulartory domain that requires minimum of 220.127.116.11 software on the Cisco WLC to recognize the new AP models. As luck would have it the WLC I had was only running 18.104.22.168 software hence the APs were unable to join controller.
If you are going to be adding new APs you had better make sure that you upgrade the software on your WLC first.
Update: Thursday September 8, 2016
It turned out we had to disconnect the APs for about 5 minutes to allow the DTLS cache on the controller to age out before the APs would join properly after upgrading the WLC.