Using Discovery Software, Illustrated (with iOS Airport Utility)

I wrote about using Discovery software, and then it dawned on me: many people prefer pictures.

Here, then, is how I use Discovery software when troubleshooting Wi-Fi, illustrated.


First, I figure out which device needs troubleshooting.  In this case, let's pretend it's one or more iPhones.




(That #nofilter picture was taken by me at about 4:50 a.m. on the morning of January 20, 2009.  It was COLD a.f. out there.)


Notice how my iPhone shows RSSI instead of signal bars.  





Once I know which device needs troubleshooting (and, PLEASE, do not skip that first step.  Troubleshooting without using the actual device that needs to use the Wi-Fi is a big waste of time that annoys users), then I need some Discovery software.

iOS: Airport Utility (Apple)
Mac OS X: Wireless Diagnostics (Apple), WiFi Explorer (Adrian Granados - $15)
Windows: Acrylic WiFi (Tarlogic), inSSIDer (Metageek - $20)
Android: WiFi Analyzer (farproc)
Chrome OS: NONE

I am troubleshooting an iPhone, so I need Apple's Airport Utility, which is available in the iOS App Store.  

(It's free.)

Once I've installed Airport Utility, then I need to enable the "Wi-Fi Scanner" function.  To my knowledge, this is the ONLY way to do Discovery using a non-jailbroken iOS device.

Go into your iPhone/iPod/iPad's Settings, then find AirPort Utility...


...then enable "Wi-Fi Scanner" at the bottom of the screen.


Once "Wi-Fi Scanner" is enabled, Airport Utility will be able to act as Discovery software.  

Now, go to the location that needs troubleshooting (and, honestly, in a lot of cases Discovery software is great for PREVENTION.  If you know that there's a place where Wi-Fi is going to be heavily used or is super important, you can do a scan using Discovery software BEFORE users start complaining) and record a Scan in AirPort Utility.

Start by opening the AirPort Utility app...


...then choose "Wi-Fi Scan"...


...you'll want to choose how long to scan for (or, for site surveys, you'll want to use a "Continuous" scan, which is the default)...


...and then after you tap "Scan" and wait for your scan to finish, you'll get an output that looks something like this:



In the lower-left corner of my scan, notice that little button that lets me export.  I recommend emailing yourself the scan output...


...which will be exported in *.csv form.



To view the scan results in a more accessible form, I like to copy-and-paste the results into a text file...


...find the text file and use Get Info...


...to change the file type to *.csv.


(It is at this point that I should note that I AM NOT A COMPUTER GUY.  I fully believe you when you tell me that there are quicker, more efficient ways to save AirPort Utility scans to *.csv.  GREAT.  Please, by all means, post them in the comments.  But I do stuff MY WAY.  Think of me as one of those little old ladies who was still paying AT&T $3.95/month to rent a landline phone in 1994.  The only thing I care about doing efficiently is making your Wi-Fi work.)

*.csv files can be opened in any spreadsheet application.  I use Numbers for Mac OS X:



Once your AirPort Utility scan is opened in your spreadsheet application, you will need to filter it so that each BSS only shows once:


Et voilá, you have effectively used Discovery software to troubleshoot an enterprise Wi-Fi network.  

From the information culled from a Discovery scan, you can often make adjustments that will fix your Wi-Fi:  

-If you see more than one of your own APs (at -80 dBm RSSI or higher) using the same/overlapping channel(s), then you can override your controller's auto-RF settings and change your APs' channels.  
-If you see more than three APs using the 2.4 GHz frequency band, then you can, again, override your controller's auto-RF settings and disable one or more of your APs' 2.4 GHz radios.  
-If you see that 5 GHz coverage is lacking, then you can go back to your site survey/design report and try to find a place to install a new AP.  

As you might expect from a tool that costs zero dollars, Discovery software has limits.  For example, when controllers' auto-RF settings keep APs' transmit power at low levels, Discovery software will be unable to diagnose an over-deployment of APs.  

To fill in your troubleshooting gaps, I strongly advise Wi-Fi people to have a Network analyzer (which is what I used to call a "Protocol analyzer", but I was told today that I'm using an outdated term) and a Spectrum analyzer at their disposal as well.  I'll cover those two Wi-Fi troubleshooting tools, with illustrations, in future blog posts.

***
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Twitter: @Ben_SniffWiFi
ben at sniffwifi dot com

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