Wireless Access

I'd like to be able to detect radars on DFS channels on an envinronment that is called "unstable" by the client. Is there a way to do that with spectrum or air monitor APs? Show ap arm history doesn't show anything and spectum/air monitor modes doesn't have cli commands to show any radar related info. Thanks in advance!

Providing your AM's and AP's are set to scan DFS channels and a radar event occurs,  you should see something similiar to the below.

(WLC-001) #show ap arm history ap-name WAP01

Interface :wifi0
ARM History
-----------
Time of Change       Old Channel  New Channel  Old Power  New Power  Reason
--------------       -----------  -----------  ---------  ---------  ------
2017-03-27 18:15:22  44+          44+          15         18         P+
2017-03-27 18:06:10  44+          44+          12         15         P+
2017-03-27 17:38:03  44+          44+          18         12         P-
2017-03-09 16:50:54  100+         44+          18         18         M
2017-03-09 04:45:53  124+         100+         18         18         I
2017-03-09 04:20:39  124+         124+         15         18         P+
2017-03-09 04:14:10  100+         124+         18         18         R
2017-03-09 02:17:44  100+         100+         15         18         P+
2017-03-09 02:12:29  108+         100+         18         18         R
2017-03-09 00:24:58  108+         108+         15         18         P+
2017-03-09 00:19:14  108+         108+         12         15         P+
2017-03-09 00:18:23  60+          108+         12         12         M
2017-03-09 00:01:36  60+          60+          9          12         P+
2017-03-08 23:59:32  124+         60+          9          9          M
2017-03-08 23:55:12  100+         124+         9          9          M
2017-03-08 23:54:54  100+         100+         15         9          P-
2017-03-08 23:39:17  108+         100+         18         18         R
2017-03-08 21:46:11  108+         108+         15         18         P+
2017-03-08 21:38:21  60+          108+         18         18         R
2017-03-08 21:34:09  60+          60+          15         18         P+
2017-03-08 21:32:43  100+         60+          15         15         M
2017-03-08 21:18:14  124+         100+         18         18         R
2017-03-08 21:05:18  124+         124+         15         18         P+
2017-03-08 21:04:55  116+         124+         15         15         M
2017-03-08 20:58:05  108+         116+         18         18         R
2017-03-08 20:17:53  108+         108+         15         18         P+
2017-03-08 20:17:44  100+         108+         18         18         R
2017-03-08 19:57:35  100+         100+         15         18         P+
2017-03-08 19:54:22  44+          100+         15         15         I
2017-03-08 19:49:29  60+          44+          15         15         M
2017-03-08 19:38:28  108+         60+          18         18         R
2017-03-08 17:52:44  108+         108+         15         18         P+
Interface :wifi1

I: Interference, R: Radar detection, N: Noise exceeded, Q: Bad Channel Quality E: Error threshold exceeded, INV: Invalid Channel, G: Rogue AP Containment, M: Empty Channel, P+: Increase Power, P-: Decrease Power, 40INT: 40MHZ intol detected on 2.4G, NO40INT: 40MHz intol cleared on 2.4G, OFF: Turn off Radio, ON: Turn on Radio

Are you able to confirm that any radar events are actually occuring? Depeding on hold old the AP's are, they may not support the feature.

https://community.arubanetworks.com/t5/Controller-Based-WLANs/What-is-Dynamic-Frequency-Selection-DFS-How-to-Enable-it-What/ta-p/179170

#show rf am-scan-profile default 

AM Scanning profile "default"
-----------------------------
Parameter                                   Value
---------                                   -----
Scan Mode                                   all-reg-domain
Dwell time: Active channels                 500
Dwell time: Regulatory Domain channels      250
Dwell time: non-Regulatory Domain channels  200
Dwell time: Rare channels                   100

Do you have any more info about your configuration, AP type, regulatory domain and so on?

Thanks

What about on spectrum monitor mode? Yes, it's possible there hasn't been any real DFS events yet.

My APs are 105s and 205s. DFS channels are selected and the regulatory domain is FI.

Hi, the spectrum monitor will show the interference but you will need to identify the signature of the radar event. Regulatory domain for Finland covers the below channels.

36, 40, 44, 48,52, 56, 60, 64,104, 108, 112, 116, 120, 124, 128, 132, 140

So if your AM's/AP's are set to scan the regulatory domain and there is a radar event you will see it in the ap arm history output. If you have a spectrum monitor running you will see the channel utilization on the respective DFS channel.

Thank you, that clears things up!