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book is organized into five parts: Part One.Overview: Provides an introduction to the range of topics covered in the book.This part includes a general overview of data communications and networking and a discussion of protocols,OSI,and the TCP/IP protocol suite. Part Two. Data Communications: Concerned primarily with the exchange of data between two directly connected devices.Within this restricted scope,the key aspects of transmission,interfacing,link control,and multiplexing are examined. Part Three. Wide Area Networks: Examines the internal mechanisms and user-network interfaces that have been developed to support voice, data, and multimedia communications over long-distance networks.The traditional technologies of packet switching and circuit switching are examined, as well as the more recent ATM and wireless WANs.Separate chapters are devoted to routing and congestion control issues that are relevant both to switched data networks and to the Internet. Part Four. Local Area Networks: Explores the technologies and architectures that have been developed for networking over shorter distances.The transmission media, topologies, and medium access control protocols that are the key ingredients of a LAN design are explored and specific standardized LAN systems examined. Part Five.Networking Protocols: Explores both the architectural principles and the mechanisms required for the exchange of data among computers, workstations,servers,and other data processing devices.Much of the material in this part relates to the TCP/IP protocol suite. Part Six.Internet Applications: Looks at a range of applications that operate over the Internet. A more detailed, chapter-by-chapter summary of each part appears at the

The material in this book is organized into four broad categories:data transmission and communication; communications networks; network protocols; and applications and security. The chapters and parts of the book are sufficiently modular to provide a great deal of flexibility in the design of courses. The following are suggestions for three different course designs: • Fundamentals of Data Communications: Parts One (overview) and Two (data communications) and Chapters 10 and 11 (circuit switching,packet switching, and ATM). • Communications Networks: If the student has a basic background in data communications, then this course could cover Parts One (overview), Three (WAN),and Four (LAN). • Computer Networks: If the student has a basic background in data communications, then this course could cover Part One (overview), Chapters 6 and 7 (data communication techniques and data link control),Part Five (protocols), and part or all of Part Six (applications). In addition,a more streamlined course that covers the entire book is possible by eliminating certain chapters that are not essential on a first reading. Chapters that could be optional are Chapters 3 (data transmission) and 4 (transmission media), if the student has a basic understanding of these topics; Chapter 8 (multiplexing);Chapter 9 (spread spectrum);Chapters 12 through 14 (routing,congestion control,cellular networks);Chapter 18 (internetworking);and Chapter 21 (network security).
Bottom-Up versus Top-Down The book is organized in a modular fashion.After reading Part One,the other parts can be read in a number of possible sequences. Figure 0.1a shows the bottom-up approach provided by reading the book from front to back.With this approach,each part builds on the material in the previous part,so that it is always clear how a given layer of functionality is supported from below.There is more material than can be comfortably covered in a single semester,but the book’s organization makes it easy to eliminate some chapters and maintain the bottom-up sequence. Figure 0.1b suggests one approach to a survey course. Some readers, and some instructors, are more comfortable with a top-down approach. After the background material (Part One), the reader continues at the application level and works down through the protocol layers.This has the advantage of immediately focusing on the most visible part of the material, the applications, and then seeing, progressively, how each layer is supported by the next layer down.Figure 0.1c is an example of a comprehensive treatment and Figure 0.1d is an