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Difference between CU, Noise and Interference

Hello everyone,

I just dug myself into a hole.  We have Cisco Prime 2.0 installed with a handful of 5508 WLCs.  I am trying to troubleshoot issues with client's losing connectivity.  And I have found AP's with high channel utilization but low interfence and zero clients associated.  Then I found AP's that have passed the Noise Profile but failed the Interference Profile.  I am getting to confused as to what these all mean.  I read definitions on each and its all jumbling together.

From what I thought, this is what each means:

CU - traffic the radio can understand that's not being generated by itself or clients associated.

Interference - signals on the same channel

Noise - signals on the same channel that are not understood at all by radio

Can someone explain in layman's terms what the difference is between channel utilization, interference and noise? 

Also, any tips on useful Prime alarms for monitoring a wireless network would be helpful as well.

Thanks everyone and happy holidays!

Hall of Fame Super Silver

Re: Difference between CU, Noise and Interference

If I had to try to explain it, it would be like this:

They are all related in ways. Interference is noise and noise is what you would say non 802.11 interference. Interference can be 802.11 and non 802.11 rf. All these add to the channel utilization.

As far as using Prime, you can click on a user and look at history, and look at where interferes are in the maps.

I typically will see what the client is doing and run a client debug and look at logs. These are my typical steps.

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Hall of Fame Super Gold

Re: Difference between CU, Noise and Interference

In regards to your clients loosing connectivity, you need to do basic troubleshooting.

1. Determine the signal strength of the SSID by looking at the client. You also need to verify the signal strength from the view of the WLC.
2. How about the client's wireless NIC drivers? Are they updated?
3. Is this issue observed with other clients or just one client?
4. Is this issue affecting similar clients, i. e. all Android, Apple, Windows, Intel chips, etc.
5. What is the location of the client vs the nearest AP?
6 What is the location of the client vs the AP the client is currently associated to?

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