In my WiFi network, I have 10 1850 series APs and 3500 series WLC. The site survey was done 2 years ago before me by one of the IT companies and each out of 10 APs was assigned 40mhz channel going sequentially from 36 to 132.
The problem is that last weeks I started to get a lot of complaints and after investigation I noticed that APs changes their channel even though DCA is turned off on them. I noticed that half of APs hears a lot of radars (even though I am not close to any radar station and I think they are false positives) in most of the channels and move to some interfered channel which creates a problem. I was advised in this forum to move all APs to non-DFS channels but 36 40 44 48 are not enough for my AP count considering they are not very far away from each other and I am using bonded channels.
What should I do?
Any help is appreciated!
Thanks in advance!
First thing is to determine which channels are seeing the DFS events, and remove them from your channel plan.
Depending on the number that are seeing it you might need to go back to 20MHz wide channels to reduce CCI.
Even if they are false positives due to regulations if the AP thinks it's seeing a DFS event it has to by law move off that channel.
I have seen other things cause DFS events like infrared/ thermal light sensors, and other things. So a site survey to try and identify the source might be required.
There are extreme measures you can go to like coating the windows in RF blocking film - but be aware that this could also take out the 3/4/5G cell signal as well
Actually I use the recommended image by Cisco (8.5.151 something like that which I do not remember and cannot check right now :D). But I kinda fixed the problem by disabling all DFS channels from DCA leaving only 4 channels and using DCA in APs with 20Mhz channels which helped.
The AP's you use lack something what Cisco calls Dual-DFS logic. Due to this the AP only uses the main chipset to determine if the detected "energy spike" is indeed DFS which results in a lot of false DFS hits. The workaround is to only use UNII-1 and UNII-3 channels (when allowed), as you already discovered :-) Sadly this can't be done on outdoor access points like the 1530...
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