802.11 Wireless Networks: The Definitive Guide, 2nd Edition

Foreword

Matthew Gast was my mentor long before I met him. I began reporting on wireless data networking in October 2000 when I discovered that Apple’s claims for its 802.11b-based AirPort Base Station were actually true.

I’d been burned with another form of wireless networking that used infrared, and had spent many fruitless hours using other “interesting” networking technologies that led to dead ends. I figured 802.11b was just another one. Was I glad I was wrong!

This discovery took me down a path that led, inexorably, to the first edition of 802.11 Wireless Networks. How did this stuff actually work as advertised? I knew plenty about the ISO model, TCP/IP, and Ethernet frames, but I couldn’t reconcile a medium in which all parties talked in the same space with what I knew about Ethernet’s methods of coping with shared contention.

Matthew taught me through words and figures that I didn’t originally understand, but returned to again and again as I descended further into technical detail in my attempts to explain Wi-Fi to a broader and broader audience through articles in The New York Times, The Seattle Times, PC World, and my own Wi-Fi Networking News (http://www.wifinetnews.com) site over the last five years.

I starting learning acronyms from 802.11 Wireless Networks and used Matthew’s book to go beyond expanding WDS into Wireless Distribution System into understanding precisely how two access points could exchange data with each other through a built-in 802.11 mechanism that allowed four parties to a packet’s transit.

Now as time went by and the 802.11 family grew and became baroque, the first edition of this title started feeling a little out of date—although it remained surprising how many “new” innovations were firmly rooted in developments of the early to mid-1990s. The alphabet soup of the first edition was gruel compared to the mulligatawny of 2005.

Matthew filled the gap between the book and contemporary wireless reality through his ongoing writing at O’Reilly’s Wireless DevCenter, which I read avidly. And somewhere in there I was introduced to Matthew at a Wi-Fi Planet conference. We hit it off immediately: I started pestering him for details about 802.1X, if I remember correctly, and he wanted to talk about books and business. (I wound up writing two editions of a general market Wi-Fi book, neither of which did nearly as well as Matthew’s extraordinarily technical one.)

Since then, I have been in the rare and privileged position to be the recipient of Matthew’s generosity with his knowledge and humble insight. Matthew isn’t one who assumes; he researches. His natural curiosity compels him to dig until he gets an answer that’s technically and logically consistent.

Take, for instance, the incredibly political and complicated evolution of the 802.1X standard. (I know, from Matthew, that it’s properly capitalized since it’s a freestanding standard not reliant on other specifications. Even the IEEE makes this mistake, and it’s their rule for capitalization that we’re both following.)

802.1X is simple enough in its use of the Extensible Authentication Protocol, a generic method of passing messages among parties to authentication. But the ways in which EAP is secured are, quite frankly, insane—reflecting Microsoft and Cisco’s parallel but conflicting attempts to control support of legacy protocols in a way that only damages easy access to its higher level of security.

Matthew eschewed the religious debate and spelled out the various methods, difficulties, and interoperability issues in an O’Reilly Network article that’s the nugget of the expanded coverage in this book. I defy any reader to find as cogent and exhaustive an explanation before this book was published. There’s nothing as clear, comprehensive, and unaffected by market politics.

At times, Matthew bemoaned the delays that led to the gap between editions of this book, due partly to his joining a startup wireless LAN switch company, but I think readers are better served through his very hard-won, late-night, long-hours knowledge.

Matthew’s relationship with 802.11 might have previously been considered that of a handy man who knew his way around the infrastructure of his house. If a toilet was running, he could replace a valve. If the living room needed new outlets, he could research the process and wire them in.

But Matthew’s new job took him allegorically from a weekend household warrior to a jack-of-all-tradesman. Matthew can tear out those inner walls, reframe, plumb, and wire them, all the while bitching about the local building code.

It’s been a pleasure knowing Matthew, and it’s even more a pleasure to introduce you to his book, and let you all in on what I and others have been more private recipients of for the last few years.

—Glenn Fleishman

Seattle, Washington

February 2005