Unfortunately both these locations were remote to our usual office so in order to find a more local instance I searched the controller and Airwave looking for APs that hadn't had any clients on their 2.4GHz radio for several days. From this a local visit and a packet capture next to the affected AP would show if the AP was in fact transmitting. From this I found an AP-105 in my building that was affected. A packet capture of the channel used by the AP showed that no beacons were being transmitted by this AP and only traffic from nearby APs was seen.
The issue could be resolved by rebooting the AP but could occur again or on different APs after some days. Aruba TAC indicated that the issue was a beacon stall where the transmitter locked up and stopped transmitting beacons. Checking the stats on the controller could show whether an AP was affected by executing this command twice and checking that the count increased:
show ap debug radio-stats ap-name "<AP-name>" radio 1 advanced | include beacon
To automate this Aruba provided an AirRecorder script that can automate CLI commands. It checked every AP to find the ones where the beacon count wasn't increasing. Therefore whilst waiting for a fix from Aruba we could locate the affected APs and reboot them.
One interesting subsequent failure mode was that after a while affected APs might start transmitting beacons but they wouldn't accept associations as they indicated they were unable to handle any more stations.
No comments:
Post a Comment