Designing the 802.11 Protocol Map poster

by Matthew Gast

Related link: http://www.oreillynet.com/pub/a/wireless/2005/05/20/80211map.html




The 802.11 Protocol Map started life as a figure that quickly grew too big to fit on the page of a book. The curse of writing is that you need to focus, word-by-word and sentence-by-sentence, on building the result. It's often myopic work, and it's easy to lose sight of the end goal.




There is an old (Chinese?) proverb about not being able to see the forest through the trees. Writing is an effort to build a forest, but you need to build from the smallest detail. You don't get to start building the forest from trees; you need to start smaller, with twigs, leaves, and branches.




Before I started writing the second edition, I tried to think about how to organize my thoughts and efforts. I kept some early sketches of the protocol map handy as a way of making sure that the book described the major blocks on the diagram. For example, the new chapter 7 is about 802.11i and the new encryption protocols that take center stage in the diagram. At one point, I even briefly contemplated attempting to have a visual table of contents, that would put chapter numbers on parts of the diagram.




As I neared the end of the revision, I received an unexpected ally in focusing on the poster. I was traveling frequently, and my laptop's battery had degraded with age to the point where I was no longer able to work through anything but the shortest airplane flight. When the battery was dead, I could resort instead to the low-tech paper-and-pen project, sketching out alternative visualizations of the protocol interrelationships.




In March, I received a full-size printed mock-up that I took everywhere with me and used to solicit comments. When I was visiting Chris Hessing, he suggested a clarification to the way that EAP was displayed on the poster. He also read the miles of text in the sidebar, and corrected the description of SecureW2.




Most recently, the poster was printed up as a foam-core sign at the Interop Labs. Explaining the difference between 802.1X and WPA is very difficult with just words. It's much easier to do in front of a visual representation of the protocols!




There's also an interesting little story about the article. I wrote most of it on a flight to Japan, but I couldn't remember which family member I'd given the book on the history of the London Underground map. At 4 am when I couldn't sleep in Tokyo, I plugged my VoIP ATA into the hotel network and made late afternoon calls to my parents and brother to get the facts straight for the article. I talked for quite some time, and the performance of my VoIP service was flawless.