What's new in the 9th edition?

As authors, we’re pleased to announce the publication of the ninth edition of Computer Networking: A Top-Down Approach. Since the publication of the first edition 25 years ago, our book has been adopted for use at thousands of colleges and universities, translated into 14 languages, and used by many hundreds of thousands of students and practitioners worldwide. We’ve heard from many of these readers and have been overwhelmed by the positive response.

We think one important reason for this success has been that our book continues to offer a fresh and timely approach to computer networking instruction. We’ve made changes in this ninth edition, but we’ve also kept unchanged what we believe (and what the instructors and students who have used our book have confirmed) to be the most important aspects of this book: its top-down approach, its focus on the Internet, its modern treatment of computer networking, its attention to both principles and practice, and its accessible style and approach. Nevertheless, the ninth edition has been revised and updated substantially.

The most important changes in this ninth edition are the following:

• Chapter 1 has been updated to reflect the ever-expanding reach and use of the Internet and its applications. A recent trend now reflected in both Chapters 1 and 2 is the continuing evolution of the Internet’s structure in which user applications communicate with numerous small-scale servers over a multi-tiered Internet topology to a flatter structure in which applications increasingly communicate with servers located close to end users in datacenters operated by hyperscalars or in large content distribution networks.
• Chapter 2 has been updated to cover the new HTTP/3 protocol and QUIC, while leaving the principles of end-to-end reliability and congestion control in HTTP/3 to Chapter 3. Chapter 2 also contains new material on content distribution networks and updated coverage of over-the-top streaming services, both reflecting the ever-increasing prevalence of application services provided by scalable, distributed application-level infrastructure.
• In Chapter 3 our foundational treatment of reliable data transfer remains unchanged, but our treatment of congestion control principles has been updated to balance coverage of traditional loss-based congestion control techniques with coverage of newer congestion control protocols (BBR in particular) that perform congestion control using measured connection delay and throughput. We also complete our treatment of QUIC (begun in Chapter 2), having studied the principles of reliable data transfer, connection management, and congestion control in this chapter.
• Chapter 4 covers the network-layer data plane. In addition to updates throughout, Section 4.5 has been restructured to highlight the architectural principles of the Internet, while still covering middleboxes.
• Chapter 5, which covers the network-layer control plane, is updated throughout and provides new material on SDN, including Google’s Orion network control plane as a case study and adds new material on the softwareization of network control. Our separate treatment of network management, and SNMP in particular, has been streamlined.
• Chapter 6, has minor updates throughout but remains relatively unchanged. The chapter contains a new section on virtual extended LANs and an updated treatment of datacenter networks, reflecting changes over the past five years..
• As noted earlier, Chapter 7 has undergone the most significant change of all chapters in this ninth edition. This reflects both the dramatic changes in wireless networking over the past five years and our own conviction that wireless networking has become an indispensable topic in an introductory networking course. As always, we have maintained an emphasis on both principles and practice. Although Chapter 7 includes a greatly expanded section on wireless channel properties and the wireless physical layer, Chapter 7’s emphasis remains firmly on the wireless network. The chapter contains new material on wireless access networks (the WiFi wireless LAN, and the 5G Radio Access Network), link-layer scheduling, network discovery and access, device energy optimizations, the 5G Core network and the softwareization of its functions, and mobility. Bluetooth, LEO Satellite, and IoT networks are also covered.
• Chapter 8, which covers network security, contains updates throughout. There is new coverage of Transport Layer Security 1.3, WiFi WPA3 security, and authentication and key agreement in WiFi and 5G networks..