catching interference

[suthomas1]

Hi,

Interference is suspected in a part of our site. We have clean air enabled on wlc, do we need to enable it on WCS also?

Other tools like inssider are supposed to be used for tracing the interference. How do we decide from the outputs that there is indeed interference in that region?

please help.

[Scott Fella]

CleanAir is enabled on the WLC. I haven't used that tool but I have used AirMagnet and Cisco's spectrum analyzer to detect interference. With CleanAir enabled you can check to see if the AP's detect interference.

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[suthomas1]

We have similar tool like air magnet. Can you please throw some light on how to identify an interference when an area is scanned.

What indications to look for to conclude that particular thing is causing interference based on the outputs.

Any specific colours or levels. Thanks.

[Scott Fella]

Well with CleanAir AP's, you can look at the monitor tab and then look at CleanAir. There you can identify what ap is seeing what interferes if any. If you have found any, then you can use your AirMagnet Spectrum Analyzer and go to that area and run the tool. The tool can tell you how strong the interference is or not. The vendors website has good explanation on how to use their tool

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[Saravanan Lakshmanan]

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a0080810880.shtml

For RF environments that are clear spaces, like factories where there are access points in a large space without walls, it might be necessary to adjust the Transmit Power Threshold from the default of -65 dBm, to a lower value like -76 dBm. This allows you to lower the co-channel interference (number of BSSID heard from a wireless client in a given moment). The best value is dependant on each site environmental characteristics, so it should be evaluated carefully with a site survey.

http://www.cisco.com/en/US/docs/wireless/controller/7.0/configuration/guide/c70cleanair.html

A Cisco CleanAir system consists of CleanAir-enabled access points, controllers, and WCS. Currently, only Cisco Aironet 3500 series access points can be configured for Cisco CleanAir. These access points collect information about all devices that operate in the ISM bands, identify and evaluate the information as a potential interference source, and forward it to the controller. The controller controls the access points, collects spectrum data, and forwards information to WCS or a Cisco mobility services engine (MSE) upon request. The controller provides a local user interface to configure basic CleanAir features and display basic spectrum information. WCS provides an advanced user interface for configuring Cisco CleanAir features, displaying information, and keeping records. The MSE is optional for the basic feature set but required for advanced features such as tracking the location of non-Wi-Fi interference devices.

http://www.cisco.com/en/US/docs/wireless/controller/7.0/configuration/guide/c70cleanair.html#wp1171853

Configuring a Spectrum Expert Connection

http://tinyurl.com/p9d2vs

20 Myths of Wi-Fi Interference

[Shankar Ramanathan]

If you have not already eliminated co-channel interference a simple test I would do is to analyze your latest run-config against WLCCA and check RX neigbours on AP nearby info in the area of issue

[suthomas1]

Can i please know what is the WLCCA and how to check the neighours for problem?

[Srin_G]

If you have enabled it in WLC its fine. WCS will show you the stats if you have added your WLC's in them. Are you using Dynamic channel allocation and TPC?

https://supportforums.cisco.com/thread/2176858  - this was my issue and disabling the 1M helped a lot. Also if you are using 3500 series there is spectrum expert mode or something which will scan the spectrum for any interferers.