I ran into an issue where some older Cisco Aironet APs (Access Points) stopped connecting to a Cisco WLC (Wireless LAN Controller). No config changes had been made and some of the Cisco Aironet APs would connect and some wouldn’t. All of them were the same model, the Cisco Aironet APs were able to ping the Cisco WLC and vice versa.
What happened is the Cisco MIC (Manufacture Installed Certificate) expired and the default setup of a Cisco WLC is to reject any Cisco Aironet AP with an expired MIC.
It looks like this could impacts every Cisco WLC when used with older Cisco Aironet APs that have an expired Cisco MIC. Cisco has a Field Notice about this issue, you can read it here FN63942.
Any Cisco Aironet AP that was manufactured from July 18, 2005 until 2017 will have a Cisco MIC that expires 10 years after the manufacture date. There seems to be no way to replace or renew that Cisco MIC, this will keep being an issue that could randomly show up until 2027 when all of them should be broken.
The reason some of my Cisco Aironet APs worked and some didn’t is because they were manufactured at different times even though they have the same model number.
The fix is super quick we just need to tell the Cisco WLC to ignore expired Cisco MICs.
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