DCA Channel Width Not Allowing 40MHz

[wifi1]

Hi

I am having issues assigning 40MHz channel width globally to access points. I have attached screenshots showing the error message that I receive.

Has anyone come across this issue before and has a fix? 

Thank you,

[Flavio Miranda]

Hi

 This is not an error actually. This a warning. 

 The WLC is telling you that 40 MHz Chanel is actually a bound of two 20 MHz channel and you need to check it properly.

 You just need to check all of them and you will not have problem.

  You can go ahead and you are good. 

[wifi1]

Hi Flavio

Thanks for your reply.

The access points never actually acquire 40MHz channel width. I tried to reboot them but still nothing. Is there anything else I should be doing to make the APs have 40MHz

Thanks.

[marce1000]

 - FYI : https://community.cisco.com/t5/wireless/automatic-channel-bonding/td-p/1689307

 M.

[wifi1]

Hi

I did read this thread but it does not really help me ... even though this is a warning and not an error, I am still unable to achieve 40MHz bonding

Thanks,

[Flavio Miranda]

It is possible to configure the channel width on the WLC leve with RRM and at Accesss Point level on the radio. Check if the AP is not set to manual with 20 MHz. If the AP is manual, change it to global. 

  Of course,  AP, WLC and client must support 40 MHz.  

[wifi1]

Hi 

The APs are set to global configuration but they do not take 40MHz. I can statically assign them.

(#######WLC) >config advanced 802.11a channel dca chan-width 40

ERROR: DCA channels mismatch for selected width 40MHz for primary channel 140. Add/Delete the primary channel and its extensions to allow the configured bandwidth.

Thanks

[Leo Laohoo]

Remove Channel 140 and try again.

[ammahend · Accepted solution]

Looking at your screenshots, Channels 116, 120, 124, and 128 are not available in the U.S. and Canada for 40-MHz channel bonding, see documentation. 

https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-10/config-guide/b_cg810/radio_resource_management.html

so remove these channels and add144 (extension for 140) and then try.

my personal suggestion is don’t use 40MHz, it hardly save you some pilot frequencies, and adds more interference in a high density AP environment, you are better off with just 20MHz. 

hope this helps. 

[Aydin Ehtibarov]

Had the same trouble, solved

The available list was 36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140

those channels are bonded this way: 36-40, 44-48, 52-56, 60-64, 100-104, 108-112, 116-120, 124-128, 132-136.  140 remain alone, no extension channel available for it in my regulatory domain. So i have unchecked 140 and all good.