Access points dropping up and down

Answered Question
Sep 12th, 2008
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I have anywhere from 5-20 access points drop up and down throughout the day out of a total of around 200. I am currently trying to go through and figure out why we our access points are having some many issues and how I might be able to resolve them.


One of the logs that I commonly see is:


AP 'exp-p13', interface '802.11a' on Controller '10.2.192.25'. Channel changed to '44' from '60' due to 'None'. Interference Energy before update is '0' and after update is '0'. Noise before update is '0' and after update is '0'. Interference before update is '0' and after update is '0'.


Is there anyway to determine what the cause of this is?


Controller Firmware: 4.2.130.0.

AP Model AIR-LAP1242AG-A-K9

IOS Version 12.4(10b)JA4


Correct Answer by jeff.kish about 8 years 9 months ago

Sounds like it's just the Radio Resource Management (RRM) on the controller. You can disable this if it's dropping clients. Go to the wireless tab, look on the left, and click on the 802.11a/n or 802.11b/g/n dropdown. Then click on the RRM dropdown, and click on Auto RF.


My advice is to change both power and channel assignment algorithms to "On Demand". You can invoke them as needed to maintain an optimum network. By default, it automatically invokes the update every 10 minutes.


Give this a try and see if it helps. If not, we can explore further.

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Correct Answer
jeff.kish Fri, 09/12/2008 - 13:32
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Sounds like it's just the Radio Resource Management (RRM) on the controller. You can disable this if it's dropping clients. Go to the wireless tab, look on the left, and click on the 802.11a/n or 802.11b/g/n dropdown. Then click on the RRM dropdown, and click on Auto RF.


My advice is to change both power and channel assignment algorithms to "On Demand". You can invoke them as needed to maintain an optimum network. By default, it automatically invokes the update every 10 minutes.


Give this a try and see if it helps. If not, we can explore further.

dbentley Mon, 09/15/2008 - 13:10
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Is anyone else doing this as well? In theory is sounds like a good idea but what other issues might it create? Just looking for input.

Scott Fella Mon, 09/15/2008 - 18:26
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If you have time sensitive app's then YES. If you have only data use and you see re-associations... also YES. I would either follow the site survey doc for channel or I would let RRM do it's thing for a couple days and get a baseline. I would then look at the power and channel to see how often it changes or not for a couple days. If I think it does change too frequently, I will set it to on demand or off. Usually if there is voice, I will set the power to 25mW and let RRM figure the channel before I disable the feature. Verify with the site survey, usually they will have the ap set to a recommended power setting when they did the site survey.


If you set it to on demand or turn the feature off, do check the channels the wlc set the ap's too.... might not be the best choice :)

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