Controller-less WLANs

In IAP, why ARM assigns channels that are removed from the customized list?

by ‎03-07-2016 02:58 PM - edited ‎03-07-2016 02:58 PM
Q:

In IAP, why ARM assigns channels that are removed from the customized list?



A:

When valid channel list is customized and some channels are removed from it, ARM still assigns the removed channel. 

For this test case:
1. Open a GUI and navigate to 'RF' -> 'Show advanced options'
2. Check the radio box next to 'Customize valid channels'
3. Click 'Edit' on 'Valid 5 GHz channels'
4. Remove some channels from the list and click 'OK' 
5. Check the channel assignment for all APs then they are still using removed channels
6. Results will remain same even after reloading the cluster.

Let's assume that we have selected below channels,

Customized channels:
a-channels 116,120,124,128,132,136,140,116+,124+,132+,36E,52E,100E,116E

After reloading the cluster , we might still notice, the removed channels in the list.

Interface :wifi0
ARM History
-----------
Time of Change       Old Channel  New Channel  Old Power  New Power  Reason
--------------       -----------  -----------  ---------  ---------  ------
2015-04-15 02:47:00  100+         44+          9          9          I      <<<<<<<<<<<<<<<< 44+ is removed channel
2015-04-15 02:38:10  52+          100+         9          9          I      <<<<<<<<<<<<<<<< 100+ is removed channel
2015-04-15 02:37:42  108+         52+          9          9          I      <<<<<<<<<<<<<<<< 52+ is removed channel
2015-04-15 02:37:23  132+         108+         9          9          I      <<<<<<<<<<<<<<<< 108+ is removed channel
2015-04-15 02:36:51  108+         132+         9          9          I
2015-04-15 02:34:14  116+         108+         9          9          I      <<<<<<<<<<<<<<<< 108+ is removed channel
2015-04-15 02:33:21  132+         116+         9          9          I
2015-04-15 02:32:13  100+         132+         9          9          I
2015-04-15 02:31:09  36+          100+         9          9          I      <<<<<<<<<<<<<<<< 100+ is removed channel
2015-04-15 02:28:21  36+          36+          Max        9          P-

The reason we see this behavior is because as per the design of the IAP , whenever channel groups are enabled, their subset channels or channel pairs are enabled automatically.

44+   is a subset of 36E channel group
100+  is a subset of 100E channel group
52+   is a subset of 52E
108+  is a subset of 100E

So since we have 80Mhz channel enabled, we notice their subsets in the ARM history. 
In order to fix this , we would have to remove the 80 MHz channel corresponding to the channel that needs to be removed. 

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