IT Infrastructure – The Infinite Source of Puzzles

If you upgrade your Cisco Wireless LAN Controller to Release 5.2, and suddenly some or all access points disappear, go to Controller, Advanced, Master Controller Mode, check the box, and power cycle the missing access points.

Root cause: 5.2 introduces CAPWAP protocol as the replacement for LWAPP. Some access points don’t transition to the new protocol unless the Master controller tells them to. Unfortunately, Master Controller Mode gets disabled after every reboot of the controller. Since you always have to reboot to apply the new software release, the problematic access points are left without guidance until you manually check that Master Controller Mode box.