Wireless Access

Occasional Contributor II

Frequent channel changes/transmit power changes

Hi, Is there any threshold value for this channel/transmit power changes per day on the AP that would trigger us to check it seriously? I believe that ARM does this changes dynamically and intelligently but when do I need to check this before the clients would be interrupted. Whenever the channel changes, does the client's association will be interrupted as well even if the client aware was enabled? Your advise is much greatly appreciated. Jaded

Valued Contributor II

Re: Frequent channel changes/transmit power changes



ARM will not trigger the AP to change the channel when clients are connected if "Client Aware is " enabled. but it will ignore this if find any RADAR signal or Rouge found in the current channel.


For your ref :

When ARM will trigger the AP to change the Channel: 

  1. The Interference Index metric on a new channel is at least “arm free-channelindex” value less than its current channel interference index value
  2. The ARM noise-threshold value is reached
  3. The ARM error-rate-threshold is reached
  4. When a Radar is detected
  5. If the AP is initially on a non-valid channel
  6. If “arm rogue-ap-aware” is enabled and an active client is found using the Rogue AP

What AP will do once it receives trigger from ARM:

1.Then it will wait for “arm wait-time” (default is 15 seconds) before it makes a change.

2.It will not make a change if “arm assignment” is set to disabled, maintain, or if “arm client-aware” is enabled and wireless clients are associated to the AP

3.Once it moves to a new channel that has the least interference then it will restart its scanning process on all Regulatory Domain channels for “arm min-scan time” 

4.It won’t change to another channel until “arm backoff-time” (default is 240 seconds) is reached.


This is how ARM will handle RF, hope you got more clarity on ARM.


Please feel free if more clarity required on this.

Venu Puduchery,
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Re: Frequent channel changes/transmit power changes

What EIRP values do you have set in ARM ?
Thank you

Victor Fabian
Lead Mobility Architect @WEI
Super Contributor I

Re: Frequent channel changes/transmit power changes


You can view the reasons for the power/channel changes with:


show ap arm history ap-name ...


Some suggested settings may be found by running this tool:




You can pretty much get rid of all the changes marked E and reduce some of the others a bit.


If you see more than the occasional isolated R (radar) event, you may have to turn off some DFS channels.


Occasional Contributor II

Re: Frequent channel changes/transmit power changes

Hi Victor,


The transmit EIRP value is 15 for radios 802.11a and 802.11g.



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