DFS Events Cisco Catalyst 9800-40 Wireless Controller 17.9.2

[SamNetech]

Hello,

I'm inquiring about the location where I should direct my attention to identify any DFS (Dynamic Frequency Selection) events. Our wireless access points are operating on DFS channels, and we've been receiving reports of WiFi disruptions. I have a suspicion that the WiFi dropouts might be related to these access points operating on DFS channels. Before I make the decision to disable DFS on these access points, I would like to confirm if there have been any DFS events recorded. Could anyone please guide me on where to find DFS event information? I'm interested in both CLI commands and GUI options for this purpose.
Cisco Catalyst 9800-40 Wireless Controller 17.9.2
mix of both 2802i (Software Version 17.9.2.52 )and 9136 wap's (Software Version 17.9.2.52)

Thank you,

[Leo Laohoo · Accepted solution]

Please read FN74035 - Cisco Access Points May Not Detect Radar on the Required Levels After Channel Availability Check Time

[eglinsky2012]

I suppose the original question is a moot point since there were no DFS events occurring. But, for those of us running a fixed version, does anyone know the answer?

[Leo Laohoo]

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@eglinsky2012 wrote:
there were no DFS events occurring

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How would anyone know? 

Are DFS channels enabled on this controller?  

[eglinsky2012]

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@Leo Laohoo wrote:

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How would anyone know? 

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Assumed due to the field notice. Though it does say the APs "may" not, not "do not". Regardless, still hoping for a direct answer to the original question.

I checked the SNMP trap controls on AireOS and IOS and don't see anything for DFS specifically. There are channel update traps, which I have enabled. Maybe they'll indicate if a channel change is due to DFS.

[Rich R]

AireOS clearly shows it in the traplog:
Fri Sep 1 18:05:33 2023 Radar signals have been detected on channel 64 by 802.11a radio with MAC: aa:bb:cc:dd:ee:ff and slot 1
9800:
I haven't personally seen a single log for radar/DFS on my 9800 WLCs but take a look at:
https://community.cisco.com/t5/wireless/cisco-9800-dfs-radar-commands/td-p/4762669
where @marce1000 provided some useful commands.  Ignore the first (completely wrong) answers somebody tried to give from ChatGPT.
You can also find some debugs you can use here:
https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/215523-quick-start-guide-on-what-logs-and-debug.html#toc-hId-2108977290