WLC> Wireless > 802.11b/g/n > 802.11n (2.4 GHz) High Throughput

Jason Aarons · ‎04-21-2011

In WLC 5508 running 7.0.98.0 I notice the default is enabled for WLC> Wireless > 802.11b/g/n > 802.11n (2.4 GHz) High Throughput. This would mean a 802.11b/g device could use 2 channels for bonding and higher throughput.

Why is the default enabled? With only 3 non-overlapping 2.4Ghz channels why would I want this enabled? Wouldn't it contribute to 2.4GHz pollution?

I run 802.11n in the 5GHz space all the time, but I've never thought it was a good idea in the 2.4GHz band. Am I wrong? What is the thought behind defaulting it to enabled? I checked the manual for 7x and it says default is enabled.

What is best practice for 802.11n in 2.4GHz space?

George Stefanick · ‎04-21-2011

Hello,

I think there is some confusion. You can run 802.11n on 2.4GHz b/g/n with 22Mhz spacing and be just fine. In fact 802.11n on 2.4Ghz is a good thing as your n clients can get on and off the network quicker then its slower counter parts.

The problem becomes when you BOND on 2.4GHz .. Whereby you take 40MHz spacing. This is a BAD thing and will cause design problems. Because, you are bonding for example channel 1/6. This means you only have 2 channels to deisgn with ..

I hope this helps...

"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
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weterry · ‎04-23-2011

I want to chime in here as well. I believe there is a wrong asumption being made.

"High Throughput" does not imply 40Mhz (bonded) channels. I think its just used as a catchy phrase for people who don't know what 802.11n is.

As far as I know, we no longer support or allow 40-mhz channels in 2.4Ghz on the WLC, and even if we did, it definitely wouldn't be the default behavior. I suspect you'll see 802.11n(2.4) clients at 144Mb data rates, while your 802.11n(5) clients get 300Mb, assuming you've enabled 40Mhz channels for 5Ghz....

-Wesley Terry

Jason Aarons · ‎04-25-2011

Where in the WLC do I set 802.11a 5GHz for 40-MHz channels? I had assumed it was Auto.

weterry · ‎04-25-2011

I'm not sure what the default behavior is for 20-mhz vs 40-mhz, but its part of configuring DCA (RRM): http://www.cisco.com/en/US/docs/wireless/controller/7.0/configuration/guide/c70rrm.html#wp1172943

I believe you can also configure it per radio the same place you would manually set an AP Radio's channel.

Jason Aarons · ‎04-25-2011

Found it under Wireless > 802.11a > RRM > DCA, however there is no Auto Option, you have to choose 20Hz or 40Mhz. I was thinking there would be a Auto option. Default is 20Mhz. My new Linksys E4200 is set to Auto and my Intel 6300 does 3x3 450MBps with 802.11an 40MHz.

I had assumed the channel bonding was set for Auto, as I assume there lots of 802.11a clients that can only do 20MHz? I don't want to hardcode it to 40MHz, but I would like those newer clients that can do 40MHz to use it! What's your thoughts? Will there eventually be a Auto option for 20MHz vs 40MHz?

weterry · ‎04-25-2011

Is your concern that enabled 40-mhz will prevent any 20-mhz client from working?

If so, then I don't think you should have that concern.

I equate 20-mhz vs 40-mhz to being like 802.11b to 802.11g, or even 802.11a to 802.11n(5).

Your 20-mhz clients should still connect and operate at 20-mhz without a care in the world.

Maybe the way to think of it is that that 40-mhz is the "Auto", where as 20-mhz means "Don't allow 40-Mhz"...?