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Interference checked by WLC and site survey?

HI Site survey can provide interference info, and WLC(new version) also can does it. Sometimes I notice the interference almost does not exist when we check Interference in WLC(new version), however it shows strong CCI/ACI if we do side survey for the same wireless network. So for the interference, which one we should believe? side survey or WLC(new version)? Thank you

VIP Advisor

I tend to say site-survey, because the detection on the WLC depends on the type of used AP. There are some models which use CleanAir, which offers a considerably better detection than the models without that feature.

Also keep in mind, some types of interference are very short lived. 

Thank you for your reply. I agree. If ap with cleanair and without cleanair work together, site survey would be better, but if all APs have cleanair, WLC would be better, can we say like that?

The theory from Cisco says yes to that question. In practice? I don't know, have never administrated a network with APs without CleanAir, since it was introduced.

Please note, for CleanAir to actually help, it needs to be enabled and the detection types need to be configured.

I think a site survey is still better though. I had experiences where I had an extremely high channel load/noise, but CleanAir was OK and not showing anything. In the end it was a in-house mobile phone antenna about half a meter from the AP away, that radiated so strong that the radios of the AP were overloaded. Once I moved it more than a Meter away, the signal was ok again. Only a frequency scanner could show this in the end.

I think you are correct especially when a unexpected event is there, such as a phone antenna is there. However recently I feel site survey just provide very rough estimate. When site survey shows severe interference, the real network shows working very well. Maybe cisco ekahau can work better. 

Scott Fella
Hall of Fame Guru

Just to add... keep in mind that a site survey is a point in time and also varies due to how the algorithm is defined for the thresholds.  Ekahau and AirMagnet as an example might take all information even with your ssid's and calculate different than what a controller might.  I have used different tools and at times, they all show different things.  I think it's really getting use to the different tools and what they can or can't provide.  

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