Reasons why you would not use UNII-2 and UNII-2 extended 5GHz channels

[RG73]

Can some one help me understand some reasons why you would not use UNII-2 and UNII-2 extended 5GHz channels?

[daswann]

Only reason I can think of is DFS (dynamic frequency selection). However most newer chipsets support it today. In practice the logic used to be if you are near an airport or a hospital don't use DFS channels. See the links below:

https://community.cisco.com/t5/wireless-mobility-documents/tpc-and-dfs-overview/ta-p/3110379

https://documentation.meraki.com/MR/WiFi_Basics_and_Best_Practices/Channel_Planning_Best_Practices

Hope this helps 

[RG73]

Thanks dastas.
Well we are both of those. Lol We are a hospital and were are near an airport.

[Leo Laohoo]

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@RG73 wrote:

Can some one help me understand some reasons why you would not use UNII-2 and UNII-2 extended 5GHz channels? 

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I got one good reason:  RADAR. 

I got another good reason:  Some wireless clients (deliberately) don't scan UNII-2/2E channels.

[RG73]

Thanks Leo Laohoo
Well we are a hospital near an airport.

[daswann]

No problem. I would still check with your Cisco S.E. But is really depends on how many channels you need, channel width 20Mhz or 40Mhz etc. and the ability of the AP to change channels during a radar event; and how seamlessly the clients can roam to the new channel. 

Cheers

[Leo Laohoo]

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@RG73 wrote:
Well we are a hospital near an airport.

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Hospital WiFi vendors are notorious for doing shortcuts (in order to fool potential customers).  

For example, we have RFID/WiFi tags that will only work with static channel, static power, UNII-1 channels and 1 Mbps data rates.  No compromises.  "This works with X thousand deployments, why would we want to change our firmware to IMPROVE our product," is their argument.  

[cvidanapathiran]

Acer C732 Chromebook.

The Chromebook would connect to the UNII-1 and UNII-3 channels right away with no issues. It took multiple connection tries to connect to the UNII-2/UNII-2e channels. The Chromebook would eventually connect to the UNII-2/2e channels but it would take several minutes for the controller to register and show the device statistics.

That is why. It all depends on the environment and how much collaboration between vendors. 

[deniseb]

Is there any update or recommendation since this article is from 2018