Today I had an issue provisioning 3 new AIR-LAP1142N-N-K9’s with the NME-AIR-WLC6-K9 module.

The AP’s and controller were all setup ok, but for some reason the AP’s didn’t want to register via CAPWAP. I had one previous working AP (which after the fix I dunno how it managed to work) that had registered. Via CDP it showed that the working AP was running C1140-K9W8-M while the busted AP’s were all running C1140-RCVK9W8-M. The recovery image is supposed to become active when the main image fails to load so I thought it may have been an issue I needed to console in to fix. Luckily it wasn’t.

All AP’s received DHCP on the right VLAN and everything else was looking fine (ACL’s etc) it was just the registration phase that didn’t work. After talking with some other engineers we found the issue was as simple as the option 43 on DHCP. It had previously been set to an ASCII option instead of HEX. Even though the Cisco docs said to set it as a HEX TLV we had it working previously on ASCII. After we hit it back to HEX all the AP’s registered without any problem.