Sniff Wi-Fi

The hot topic in WiFi nowadays is high density (HD), and for good reason.  It seems you can't swing a dead cat anymore without hitting some place (concert hall, convention center, tourist trap) where there's an attempt to offload cell phone data onto a WiFi network.  The most interesting thing about HD WiFi to yours truly is that it's the same fundamentals we've always known about, just recycled. If you were one of the lucky (unlucky?) ones to work in WiFi during its more formative years, you may have been taught certain basic concepts about WiFi.  For the author, fond memories still remain of sitting an Enterprise WLAN Administration course way back in 2003 (taught by noted Massachusetts Yankees fan David Westcott ) as part of my preparation for the certified wireless network administrator ( CWNA ) exam. What did Mr. Westcott teach us lo these many years ago? Plan out your space alternating between channels 1, 6 and 11 in the 2.4 GHz band. If APs are spaced t...

Yay, a new iPhone!   So sayeth me, my relatives (one of whom will receive my old iPhone), California (who will receive 8.75% in sales tax on the FULL UNLOCKED PRICE of the phone because California has a ludicrous sales tax law that taxes the pre-discount price of mobile phones) and anyone else who has been waiting for the iPhone to finally support 5 GHz WiFi.   But wait, there's more.  The iPad has long supported 5 GHz 802.11n WiFi, but the iPhone 5 does the iPad one better.  How?  Read on, amigos. Though Apple's most popular iOS device, the iPhone, has eschewed 5 GHz WiFi until iPhone 5, iOS-based access to 5 GHz channels (numbered 36 through 165) has been available in every iPad model. The iPad has always been 802.11n, which is good.  But the WiFi adapter in the iPad has always supported the bare minimum 802.11n , which is bad.  (Specifically, 65 Mbps Data Rate bad.)  This meant that an iPad is going to take about three times as much cha...

WildPackets OmniPeek has long been my favorite WiFi sniffing software, but lately this blog has been short on posts about it.  That needs to change.  So today I start a multi-part series (number of parts to be determined) on how I use OmniPeek to help me plan for and troubleshoot mobile devices. Mobility (defined here as seamless roaming between WiFi access points [APs]) is a longstanding enterprise WLAN issue that has kind of taken a back seat to supporting personal devices (a.k.a. BYOD).  For many enterprises, mobility remains important.  Car dealerships with push-to-talk handsets, warehouses with barcode/RFID scanners and retail locations with point-of-sale terminals are all examples of locations that require user devices to move around a large area without dropping connections, losing speed or experiencing choppy service. The solution to supporting mobility is to make sure that APs have adequate overlapping coverage without interfering.  It sounds simpl...