topic Controller places ap's on same channel in Wireless

Controller places ap's on same channel

Daniel Justice — Sun, 04 Jul 2021 06:17:11 GMT

I am studying for the CCNA Wireless, and just acquired a WLC 2125 and some ap's to lab with for a bit. I have the channel and power settings set to global, and there are 2 1142's attached to the controller in local mode. Both are accept clients and roaming seems to work as it should. However, I also have an autonomous ap thrown in the mix (another 1142) to see how the controller reacts. It appears quite content to place one of the controller-based ap's on the exact same channel as the autonomous ap 3 feet away from it. The controller sees it as a rogue at -27 RSSI on the same channel, so it's by no means a ghost. Any ideas on settings I should check? I figured the controller would try to balance on 1,6,11 based on the environment as well as its members. Here is a screen shot of what I am seeing.

Re: Controller places ap's on same channel

Scott Fella — Tue, 01 Jan 2013 05:03:27 GMT

Do have the DCA set right?

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Controller places ap's on same channel

Daniel Justice — Tue, 01 Jan 2013 17:26:53 GMT

I haven't changed them from "stock" settings. It is set to "automatic," 10 minute interval, anchor time 0, avoid foreign AP interference, and avoid .11b noise.

Re: Controller places ap's on same channel

Scott Fella — Tue, 01 Jan 2013 17:37:57 GMT

Well you need to avoid foreign ap interference. The algorithm will decide what channel is best and it can be a channel that is already used.

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Controller places ap's on same channel

Saravanan Lakshmanan — Tue, 01 Jan 2013 20:31:12 GMT

Q. I have set the Radio Resource Management (RRM) to the default settings on my WLC. However, I cannot find my RRM to automatically adjust the channel and power levels. Why?

A. RRM possibly does not work for any of these reasons

The RRM works only if an AP hears RF signals from at least 3 nearby APs, with a third neighbor that transmits a signal strength greater than -65dbm. If any of these condition fails, the RRM does not work.

The auto RRM feature includes channel adjustment, power adjustment, and coverage hole detection. These features do not work if they are either disabled or the method of assignment is chosen as manual.

While a fresh AP boots up, it initially keeps power at the default value of 1 (highest). When it sees 3 or more APs with power levels greater than -65 dBm (in the same RF-Mobility-Domain and same channel), it attempts RRM first (change channels). If not successful because the channels are manually fixed or there are more APs than channels available, the AP drops its power level.

Refer to Radio Resource Management: Concepts for more information on how RRM works

http://www.cisco.com/en/US/products/ps6366/products_qanda_item09186a008064a991.shtml

Controller places ap's on same channel

Daniel Justice — Wed, 02 Jan 2013 01:09:26 GMT

That makes perfect sense, as I only have 2 AP's on the controller at this time. I'll find a third and see what happens. Thanks for the info!