When there is a problem with a wireless client, and you have determined the coverage is good. A look into the spectrum to troubleshoot the layer 1 characteristics is a good start.
This we do to rule out or find any interference on the spectrum.
For that we use Chanalyzer. It comes with an accessory to connect to a CleanAir AP to view this spectrum data.
The best part of using a CleanAir AP is being able to do it remotely. That’s right, doing spectrum analysis from your seat several miles, even hundreds of miles, away from the source.
Granted, the view of the spectrum is from the AP’s perspective but it sure beats flying out there. It works great in a pinch.
Please Note: Spectrum Expert Connect is not supported on Cisco Aironet 1810 OEAP, 1810W, 1830, 1850, 2800,9120,9130, and 3800 Series APs.
The obvious requirement here is CleanAir must be enabled on the AP.
You can connect to an AP that is actively serving clients but you will only be able to see the spectrum from its operating channel. If the AP is serving clients on channel 36, then you will only see the spectrum of that channel.
In this post, I am using a Cisco Aironet 2702i
You may be familiar with Local mode which tunnels the user traffic back to the controller. This mode only shows you the spectrum on the serving channel.
Monitor mode will scan for interferers on all channels but will not serve any clients. SE-Connect is the mode we want to use to connect Chanalyzer to a CleanAir.
AP. This mode also doesn’t serve clients but will provide you with the spectrum data you seek.
From the Monitor page, click on Wireless.
From the list of APs, click on the one that will be used for Spectrum Expert.
From the General tab of the AP, click the dropdown for AP Mode and select SE-Connect (if you only want to see the current channel, you can let it in local mode). Click Apply
The AP will reboot into SE-Connect mode. Get coffee. This will take a few minutes.
When the AP reconnects to the controller, navigate to the General tab and copy the Network Spectrum Interface (NSI) Key. This will be used to authenticate the AP in Chanalyzer.
Please Note: You must have a license to the CleanAir Accessory to connect Chanalyzer to an AP.
Click on CleanAir from the top menu and click on Connect to a CleanAir AP
Type in the IP address of the AP, the NSI Key you copied from the Cisco WLC, and give it a name. Then click Connect.
Chanalyzer will establish a connection to the Spectrum Expert enabled AP.
Once connected you will see the panes populate with colors.
You see some interference there on Channel 4 (BLE) but it’s not very loud at the place where I stand, so from my perspective it will not cause so much interference, also because it’s on the tail of channel 6 and they WiFi still have space to send packets true closer it will also not interfere so much.