Upto my knowledge, this warning means that an unknown 802.11 entity seems to be sending 802.11 frames that are normally expected from one of the controller's APs.
This is only cosmetic and does not affect the network.
Workaround can be the following
(1) On the controller cli:
show advanced 802.11a monitor
For example, it may look like:
Default 802.11a AP monitoring
802.11a Monitor Mode........................... enable
802.11a Monitor Channels....................... Country channels
802.11a AP Coverage Interval................... 180 seconds
802.11a AP Load Interval....................... 60 seconds
802.11a AP Noise Interval...................... 180 seconds
802.11a AP Signal Strength Interval............ 60 seconds
(2) If "802.11a monitor channels" is set to "All Channels", then set it to "country" channels:
config advanced 802.11a monitor channel-list country
Confirm the change using the show cmd in (1).
And then check if the AP impersonation alarms are still raised when monitoring is set to only "Country Channels". If the alarms are still raised, then additional debugs may be collected with the help of TAC.
