Previously good 350 AP's stop authenticating clients
I have about 20 350-series AP's with 350-series PCMCIA client adapters that have been in production for over a year now. Lately I've had several AP's in the field stop authenticating clients, although no configuration changes had been made. These AP's had been working fine previously. Sometimes a reset of the AP will seem to resolve the problem (they start authenticating clients again), but sometimes not.
I brought one of the problem AP's to my desk for some testing. I placed my laptop about 12 inches from the AP. When I boot an identically configured 350 AP that we had as a spare my laptop connects to it just fine. When I power that one off and boot up the problem 350 the client cannot associate.
I've tried locking it down to channels 1, 6, and 11 - none worked (even though channel 1 works fine for the spare AP). I had upgraded the firmware to 12.03T a couple weeks ago so I tried downgrading back to 12.00T but no luck. I've tried several different 350 client adapters, I've verified and reverified the SSID and WEP keys, I've even blown away the configuration and reconfigured it again from scratch - this AP just refuses to authenticate clients.
With the problem AP I get PLCP CRC Errors in the Receive stats of the AP Radio Port screen and on the client I get PLCP CRC Errors and SSID mismatches in the Receive stats in the ACU. I've done some quick research and this would seem to indicate interference - but then why would another AP work just fine in identical conditions?
As I mentioned I've had several (3 or 4) 350's exhibiting this problem out of the 20 or so in production. Is there an identified issue with these radios that causes many of them to go flaky after a certain amount of time? Is this an acceptable failure rate for the 350-series? Has anyone else seen these problems on AP's that had previously been working fine?
Re: Previously good 350 AP's stop authenticating clients
As far as the CRC errors are concerened , we can attribute them to a) packet collisions to dense population of clients ,overlapping access point coverage on a channel , for this you can try putting the APs on a different channel, b)the presence of other 2.4-GHz signals from devices such as microwave ovens, wireless handset phones, etc , if you have any of these try removing them.