Several colleagues of ours have helped us during this project. However, three were absolutely key to the creation of this book:

Patrick Ames led this project in all its nontechnical aspects, allowing Miguel and Peter to focus on writing.

Aviva Garrett played the key role of the editorial review of the entire book and also guided Miguel and Peter in how to improve the book’s organization and contents.

Steven Wong (Juniper JTAC) provided technical reviews for much of the book while sharing his immense knowledge of QOS.

The authors would also like to gratefully thank the following people: Antoine Sibout, Bobby Vandalore, Guy Davies, Jeff Doyle, John Peach, Jos Bazelmans, Kannan Kothandaraman, Margarida Correia, and Pedro Marques.

Finally, the authors would like to express their personal thanks:

Miguel: I would like to dedicate this book to Maria Eugénia Barreiros and to my grandparents José Silva and Dores Vilela.

Peter: My work on this book was possible only with the understanding and patience of the most dear ones in my life, my wife Lena and my great kids Ida and Oskar.