Wireless Access

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What does the Rx RADAR Events counter represent?

We have a 5GHz point-to-point setup with two AP175's over a (very short) distance of 50 meters. The config is quite straight forward and follows the recommendations of the VRD.

 

The connection has a good speed 300/300, and an RSSI >64. Sometimes the connection isn't stable (loses connectivity for longer periods), and because in our regulatority domain (NL) we're forced to use DFS channels, I'm trying to find out if that might be causing problems.

 

There are no DFS events in the ap debug log, but the output of

show ap debug radio-stats ap-name "apname" radio 0 advanced shows RX RADAR events:

 

NLXYZ-AP04 - Rx RADAR Events                     1110867 -> From a few weeks, and still counting. Reboot counter of mesh point is about 170 in the same period.

 

Does anyone know what this counter represents, and also if in this case (only DFS channels) we should set ARM-channel assignment from the recommended 'assignment disabled'  to something more dynamic?

 

Johan

 

Guru Elite

Re: What does the Rx RADAR Events counter represent?

Jlam,

 

That means it has observed radar in the area.

 

It looks like you ARE forced to use DFS channels for outdoor in the Netherlands.  The wireless log (show log wireless all) would show your radar events.

 

You should set ARM assignment to "Single Band" so that if there is radar it will change channel.  Setting ARM to disable will only have it on one bonded channel.  If that channel "sees" radar it must stop transmitting on that channel for 30 minutes and your wireless will be down that whole time.  If you have it set to "single band", it will change to another available channel after a 60 second outage, instead.  "listening" to a DFS channel for 60 seconds to see if there is radar is mandatory and there is no workaround for that.  You should probably make that change as soon as possible.

 

Another thing you might try to do is to set "allowed bands for 40mhz channels" to "none" in the ARM profile so that you only use 20mhz channels.  Using bonded channels means that if either of the two bonded channels sees radar, you must leave the channel.  Using 20 mhz channels might reduce that.  You would be attempting to choose stability over throughput, but at that distance 20 mhz channels could be more reliable.

 



Colin Joseph
Aruba Customer Engineering

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Re: What does the Rx RADAR Events counter represent?

Hi Colin,

 

Thanks a lot! I'll configure those settings straight away and see what the outcome is.

 

Johan

New Contributor

Re: What does the Rx RADAR Events counter represent?

It definitely was DFS. Changing to 20MHz, and auto channel assignment did the trick. Thanks again!

 

Log excerpts (got multiple of them on different channels):

 

show log wireless all | include NLXYZ
Nov 27 16:10:57 :404088:  <WARN> |AP NLXYZ-AP05@10.102.0.51 sapd|  AM d8:c7:c8:00:55:68: ARM HT Radar Detected Trigger Current Channel old 132+ new 100+/4


#show ap debug driver-log ap-name NLXYZ-AP05 | include RADAR
Thu Nov 27 14:10:57 2014:79     101865.135780 wifi0: RADAR DETECTED ON CHANNEL 132 pulseid : 34
79     101865.135780 wifi0: RADAR DETECTED ON CHANNEL 132 pulseid : 34

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