Force 802.11n on Airport Extreme…
- August 10th, 2010
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The company I work for decided to send me to a wireless networking class this week. I like to think I know a fair amount about wireless networking, but I wanted to learn more so as to get the most functionality out of our Wireless Control System (WCS), Wireless LAN Controllers (WLC) and lightweight access points we have deployed across the enterprise. After the first day, the instructor got me thinking about my own wireless setup at home. The burning question I had was whether or not my Macs were utilizing 802.11n. I have 3 Airport Extremes, two of which are “N” capable. The third runs a separate SSID not used by any of my Macs. When I finally got home and had a chance to poke around their configuration a bit…well, lets just say I was surprised to find out that every wireless device (including my “N” capable Macs) were running at 802.11g even though they were associated to the “N” APs!
The next question I had was how to get them to connect at 802.11n rates. Well, if you open Airport Utility, you’ll find under the “Wireless” tab the ability to modify the “Radio Mode.” If you hold down the “Alt/Option” key and click the drop down, you’ll be presented with options you may never have seen before (At least I didn’t). Now, I have the ability to select 802.11n only (5 GHz) which my Macs will support. The only draw back is that my iPhone 4 only does 802.11n in the 2.4 GHz frequency spectrum. That’s unfortunate because the 2.4 GHz spectrum is heavily used (i.e. wireless phones and microwaves). However, there is another useful feature that Airport Utility gives us to play with. If you click the “Advanced” icon at the top, then Logs and Statistics, you’ll see that you can check logs and view information about currently associated wireless clients. The “Wireless Clients” tab includes Signal and Noise information about clients currently associated to that AP. If you have a good signal to noise ratio (SNR) feel free to run in the 2.4 GHz spectrum (until someone wants popcorn). To calculate SNR for a wireless AP, subtract Signal from Noise. My values were -71 dBm and -96 dBm, respectively. This gave me a SNR of 25dB which is good enough for wireless VoIP. So, I decided to stay in the 2.4 GHz range.
There is, however, one last thing I think I should mention. The two “N” capable APs I have are different hardware revisions. The newest of the two has dual radios and the other does not. The way to tell if your AP has two radios is whether or not you have the ability to setup a “Guest” network. The reason I bring this up is that you may run into different options from the “Radio Mode” drop down menu depending on which hardware you own. Enjoy!
-Tim







