Computer Networks, Fourth Edition, continues to provide an enduring, practical understanding of networks and their building blocks through rich, example-based instruction. This expanded and completely updated edition covers the why of network design, focusing not just the specifications comprising today's systems but how key technologies and protocols actually work in the real world to solve specific problems. It is the only introductory computer networking book written by authors who have had first-hand experience with many of the protocols discussed in the text, who have actually designed some of them as well, and who are still actively designing the computer networks today. The book makes less use of computer code to explain protocols than earlier editions. Moreover, this new edition shifts the focus somewhat higher in the protocol stack where there is generally more innovative and exciting work going on at the application and session layers than at the link and physical layers. Other new features are: increased accessibility by clearly separating the advanced material from more fundamental via special headings and boxed features; the material is structured in such a way as to make it easier to teach top-down. Furthermore, the book outstrips the competitors in offering a more robust ancillary package for student and instructor support. The text is complemented with figures as well as links to networking resources on the Web and links to author-created materials on author-maintained Web site. Computer Networks, Fourth Edition, will be an invaluable resource for networking professionals and upper level undergraduate and graduate students in CS, EE, and CSE programs. - Completely updated with new sidebar discussions that cover the deployment status of protocols described in the book. - Addition of sizeable number of new exercises and solutions.