12-15-2015 11:25 AM - edited 07-05-2021 04:23 AM
I have a (hopefully) quick question about 40Mhz wide channels with the 5GHz spectrum. If I am using 40Mhz wide channels in my wireless network and I disable channel 149, does that mean channel 153 will not be used even if it's still enabled? From what I understand, when using 40Mhz wide channels, channel 149 and 153 are bonded and disabling 149 means 153 will not be used either.
Thanks for the help!
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12-15-2015 02:43 PM
Even if you enable 40MHz channel width, it does not mean only 40MHz capable clients can join. If client is only 20MHz, still they able to connect.
In your scenario, yes CH 153 won't be part of any 40MHz as you disable CH149. Still CH 153 should be in operation as 20MHz if software code allow this.
I think feature called "Dynamic Bandwidth Selection- DBS " introduced in AireOS 8.1 onward for AP to dynamically changing this.
http://wirelessonthego.postach.io/post/cisco-wlc-8-1-dynamic-bandwidth-selection-dbs
HTH
Rasika
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12-15-2015 02:43 PM
Even if you enable 40MHz channel width, it does not mean only 40MHz capable clients can join. If client is only 20MHz, still they able to connect.
In your scenario, yes CH 153 won't be part of any 40MHz as you disable CH149. Still CH 153 should be in operation as 20MHz if software code allow this.
I think feature called "Dynamic Bandwidth Selection- DBS " introduced in AireOS 8.1 onward for AP to dynamically changing this.
http://wirelessonthego.postach.io/post/cisco-wlc-8-1-dynamic-bandwidth-selection-dbs
HTH
Rasika
*** Pls rate all useful responses ***
12-15-2015 03:05 PM
Thanks for the reply. This is some good information. Thanks for the link!
12-15-2015 03:07 PM
No problem.
Pls test these features out (I haven't done this by myself to understand how exactly it works in each scenario) let us know what you find.
Rasika
12-15-2015 03:23 PM
I'm planning on maybe testing this in the lab. I'd like to see DBS in action now. Though my lab WLC is running 8.0 and I haven't upgraded to 8.1 because I don't think there's a way to downgrade back to 8.0.
PS-
I really enjoy your website. It is a great site with a ton of information. I am on it quite a bit and always learn something new. Definitely a great help with studying for my wireless exams! Thanks for all your help!
12-15-2015 03:29 PM
Though my lab WLC is running 8.0 and I haven't upgraded to 8.1 because I don't think there's a way to downgrade back to 8.0.
I do not think this is true, you should be able to downgrade your WLC. From where you got that info ?
Good to know you are fan of my blog. I'll try my best to find time for keep that going :)
Rasika
12-15-2015 03:40 PM
In the release notes for 8.1 it mentions they don't recommend downgrading to a release older than 8.1 after upgrading.
In the notes, under "Supported Cisco Wireless Controller Platforms"
http://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn81mr3.html#pgfId-1317023
Please do keep the blog going!
12-15-2015 04:00 PM
Ok, yes it is not a good practice, but in certain times you have to do it (code issues/rolling back)
But I do not believe there is a technical limitation, so if it is lab, I will do it & test features as I need.
Rasika
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