ACKNOWLEDGMENTS I would like to thank various leaders in their respective fi elds who have given me their time and read and reviewed selected chapters of this work. Their com- ments have made this a much better book than it would have been without their involvement. Any errors that remain are mine. I would like to thank colleagues at Juniper Networks, Inc., who gave their time and effort to create this network. In many cases, they also helped with the book. It starts at the top with Scott Kriens, who has created an environment where creativ- ity and exploration are encouraged. Thanks, Scott! The list goes on to include June Loy, Aviva Garrett, Michael Tallon, Patrick Ames, Jason Lloyd, Mark Whittiker, Kent Ketell, and Jeremy Pruitt. Finally I would like to thank my lead technical reviewers, Joel Jaeggli and Robin Pimentel, for the careful scrutiny they gave the book and the many fi ne corrections and comments they provided. Lead Technical Reviewers Joel Jaeggli works in the security and mobile connectivity group within Nokia. His time is divided between the operation of the nokia.net (AS 14277) research network and supporting the strategic planning needs of Nokia’s security business. Projects with former employer, the University of Oregon, included the Network Startup Resource Center, Oregon Route views project, the Beyond BGP Project, and the Oregon Videolab. He is an active participant in several industry-related groups including the IETF (working group chair) and NANOG (two terms on the program committee). Joel frequently participates as an instructor or presenter at regional and international network meetings on Internet services and security-related topics. Robin Pimentel is currently a network engineer at Facebook, where he helps the production network sustain growth alongside Facebook’s user and application growth. Previously, Robin worked on the production network teams at Google and Yahoo. Robin also spent 6 years at Teradyne where he performed many network- ing, security, and Unix infrastructure engineering roles. Prior to his career in com- puter networks, Robin worked at Cadence Design Systems and Intel Corporation. While working in the chip sector, Robin specialized in silicon place and route, VHDL-based behavioral logic validation, and gate-level logic validation for on-chip memories. Preface xxix Walter Goralski has worked in the telecommunications and networking industry since 1970. He spent 14 years in the Bell System. After that he worked with mini- computers and LANs at Wang Laboratories and with the Internet at Pace Univer- sity, where he was a graduate professor for 15 years. He joined Juniper Networks as a senior staff engineer in 2000 after 8 years as a technical trainer. Goralski is the author of 10 books about networking, including the bestselling SONET/SDH (now in its third edition). He has a master’s degree in computer science from Pace University. About the Author PART I All networks, from the smallest LAN to the global Internet, consist of similar components. Layered protocols are the rule, and this part of the book examines protocol suites, network devices, and the frames used on links that connect the devices. ■ Chapter 1—Protocols and Layers ■ Chapter 2—TCP/IP Protocols and Devices ■ Chapter 3—Network Link Technologies Networking Basics . race across the Internet. A great deal of the discussion will revolve around the TCP/IP protocol suite, the protocols on which the Internet is built. The network that will run these protocols. rules ϭ Gig Ethernet Note: All links use 10.0.x.y addressing only the last two octets are shown. FIGURE 1.1 The Illustrated Network, showing the routers, links, and hosts on the network. Many of the layer. telecommunications context. There is a link to the global Internet and to a home-based wireless LAN as well. The home offi ce link uses digital Major Parts of the Illustrated Network The Illustrated Network