rrior-your comments were always spot-on, and your efforts made this a better book. I would like to thank another tech reviewer, Yves Eynard: you caught some mistakes that floored me, and I appreciate the time you spent reviewing. This is a better book for your efforts. I would like to thank Paul John for letting me use the lab while he was using it for his CCIE studies. I would like to thank Henri Tohme and Lou Marchese for understanding my need to finish this book, and for accommodating me within the limits placed upon them. I would like to thank Sal Conde and Ed Hom for access to 6509E switches and modules. I would like to thank Christopher Leong for doing some last-minute technical reviews on a couple of the telecom chapters. I would like to thank Mike Loukides, my editor, for not cutting me any slack, for not giving up on me, and for giving me my chance in the first place. You have helped me become a better writer, and I cannot thank you enough. Preface I would like to thank Rachel Head, the copyeditor who made this a much more readable book. I would like to thank Robert Romano, senior technical illustrator at O'Reilly, for work- ing to keep the illustrations in this book as close to my original drawings as possible. I would like to thank all the wonderful people at O'Reilly. Writing this book was an awesome experience, due in large part to the people I worked with at O'Reilly. I would like to thank my good friend, John Tocado, who once told me, "If you want to write, then write!" This book is proof that you can change someone's life with a single sentence. You'll argue that I changed my own life, and that's fine, but you'd be wrong. When I was overwhelmed with the amount of remaining work to be done, I seriously considered giving up. Your words are the reason I did not. Thank you. I cannot begin to thank everyone else who has given me encouragement. Living and working with a writer must, at times, be maddening. Under the burden of deadlines, I've no doubt been cranky, annoying, and frustrating, for which I a