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| Information Center |
Preface
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Preface Data communications and networking may be the fastest growing technologies in our culture today. One of the ramifications of that growth is a dramatic increase in the num-ber of professions where an understanding of these technologies is essential for success—and a proportionate increase in the number and types of students taking courses to learn about them. Today, students wanting to understand the concepts and mechanisms underlying telecommunications and networking come from a variety of academic and professional backgrounds. To be useful, a textbook on data communica-tions and networking must be accessible to students without technical backgrounds while still providing substance comprehensive enough to challenge more experienced readers. This text is written with this new mix of students in mind. Features of the Book Several features of this text are designed to make it particularly easy for students to understand data communications and networking. Structure We have used the seven-layer OSI model as the framework for the text not only because a thorough understanding of the model is essential to understanding most current net-working theory but also because it is based on a structure of interdependencies: Each layer builds upon the layer beneath it and supports the layer above it. In the same way, each concept introduced in our text builds upon the concepts examined in the previous sections. The OSI model was chosen because it is a model, not a protocol. The model is independent of any protocol such as TCP/IP, IPX/SPX (Novell), or AppleTalk. We believe that in an introductory course, the model should be understood before the actual protocols are discussed. The OSI model shows the layered architecture necessary for the design of network systems. This text is designed for students with little or no background in telecommunica-tion or data communication. For this reason, we use a bottom-up approach. In this approach, students can learn first about telecommunications (lower layers) before learning about data communications (upper layers). For example, students can learn about signaling, encoding, modulating, and error detection before learning about data transfer across the Internet. This eliminates the need for two courses: one for telecom-munications and one for data communications. The first nine chapters emphasize the physical layer, which is essential for under-standing the rest of the layers. These chapters are particularly needed for students with no background in networking and telecommunications. Chapters 10 through 12 describe all issues related to local area networks. Chapter 13 discusses metropolitan area networks. Chapter 14 describes switching techniques as background preparation for wide area networks. Chapters 15 to 20 discuss topics associated with wide area networks. Chapter 21 discusses the network layer functions and the topic of internetworking local and wide area networks together. Chapters 22 and 23 focus on upper layer protocols (transport, session, presentation, and application layers). Chapters 24 and 25 are dedicated to the TCP/IP protocol suite. These two chapters give a brief introduction and prepare the students for a course on the TCP/IP protocol suite. Visual Approach The book presents highly technical subject matter without complex formulas by using a balance of text and figures. The approximately 700 figures accompanying the text pro-vide a visual and intuitive opportunity for understanding the material. Figures are par-ticularly important in explaining networking concepts, which are based on connections and transmission. These are both often more easily grasped visually than verbally. For example, Figure 3.8 shows the encapsulation of a network-layer packet in a data-link-layer frame. The figure also shows how network-layer addresses are unchanged compared to the data-link-layer addresses that change from station to station. Another figure, Figure 5.36, shows how an 8-QAM signal can carry three bits in each baud. Figure 8.4 clearly shows how FDM combines three modulated signals into one composite signal. Figures 25.3, 25.4, 25.5, and 25.6 show how the domain name system is divided into three domains: country, generic, and inverse domains. Highlighted Points We have repeated important concepts in boxes for quick reference and immediate attention. Examples and Applications Whenever appropriate, we have included examples that illustrate the concept introduced in the text. They also help students do the exercises at the end of each chapter. Also, we have added real-life applications throughout each chapter. For example, in Chapter 8, after a discussion of FDM, we give an application, the analog hierarchy of the telephone system. Similarly, after discussion of TDM, we give an application, the DS hierarchy of the telephone system. Summary Each chapter ends with a summary of the material covered in that chapter. The summary is a brief overview of all the important points in the chapter. Key Terms Each chapter includes a list of key terms used throughout the chapter for a quick reference. Practice Set Each chapter includes a practice set designed to reinforce salient concepts and encourage students to apply them. It consists of three parts: review questions, multiple choice questions, and exercises. Review questions are intended to test students for their first-level understanding of the material presented in the chapter. Multiple choice questions test students’ grasp of basic concepts and terminology. Exercises require deeper under-standing of the material. Appendixes The appendixes are intended to provide quick reference material or a review of materials needed to understand the concepts discussed in the book. Glossary and Acronyms The book contains an extensive glossary. A list of acronyms appears on the endpapers. Changes in the Second Edition In this edition, material on the newer technologies has been added, the contents of the chapters have been revised, and the end materials have been augmented and improved. New Material We have added the following new material:
All chapters have been revised, particularly Chapters 4, 9, 18, and 19 and Appendix H. End Material Augmentation and Improvement
Several examples are added to many chapters to
clarify the materials. Online Supplementary Material at www.mhhe.com/forouzan Online Learning Center The McGraw-Hill Online Learning Center is a "digital cartridge" that contains the book’s pedagogy and supplements. As students read through Data Communications and Networking, they can go online to take self-grading quizzes. They also get appropriate access to lecture materials such as PowerPoint slides and animated figures from the book. Solutions are also available over the Web. The solutions to odd-numbered problems are provided to students, and instructors can use a password to access the complete set of solutions.Additionally, McGraw-Hill makes it easy to create a website for your networking course with an exclusive McGraw-Hill product called PageOut. It requires no prior knowledge of HTML, no long hours, and no design skills on your part. Instead, Page-Out offers a series of templates. Simply fill them with your course information and click on one of 16 designs. The process takes under an hour and leaves you with a pro-fessionally designed website. Although PageOut offers "instant" development, the finished website offers powerful features. An interactive course syllabus allows you to post content to coincide with your lectures, so when students visit your PageOut website, your syllabus will direct them to components of Forouzan’s Online Learning Center, or specific material of your own. How to Use the Book This book is written for both an academic and a professional audience. The book can be used as a self-study guide for interested professionals. As a textbook, it can be used for a one-semester or one-quarter course. The chapters are organized to provide a great deal of flexibility. The following are some guidelines:
Acknowledgments It is obvious that the development of a book of this scope needs the support of manypeople. We must thank the De Anza students and staff; their encouragement and supportenabled the project to materialize and contributed to its success. We especially thank Claudia Gohler and Anastasia Mazharina for their tremendous assistance in preparing solutions to the end materials. The most important contribution to the development of a book such as this comes from peer reviews. We cannot express our gratitude in words to the many reviewers who spent numerous hours reading the manuscript and providing us with helpful comments and ideas. We would especially like to acknowledge the contributions of the following reviewers for the first and second editions of this book. First edition reviewers: Russell J. Clark, University of DaytonCharles K. Davis, University of Houston James M. Frazier, University of North Carolina at Charlotte John W. Gray, University of Massachusetts at Dartmouth Thomas F. Hain, University of South Alabama Paul N. Higbee, University of North Florida Seung Bae Im, California State University at Chico Rose M. Laird, Northern Virginia Community College Jorg Liebeherr, University of Virginia Wallace C. Liu, California State University at Fresno Peter Maggiacomo, Sinclair Community College Larry D. Owens, California State University at Fresno Michael Peterson, Iowa Western Community College Satya Prakash Saraswat, Bentley College T. Radhakrishnan, Concordia University Heidi Schmidt, San Francisco State University Gordon Springer, University of Missouri at Columbia Second edition reviewers: Jay Benson, Anne Arundel Community CollegeJohn Besci, Clayton College and State University David L. Doss, Illinois State University Timothy W. Price, Indiana University–Purdue University Indianapolis Xiaojun Shen, University of Missouri, Kansas City Zixiang (Alex) Tan, Syracuse University Special thanks go to the staff of McGraw-Hill. Betsy Jones, our executive editor, proved how a proficient editor can make the impossible possible. Emily Gray, the developmental editor, gave us help whenever we needed it. Amy Hill, our project manager, guided us through the production process with enormous enthusiasm. We also thank Heather Burbridge in production, Gino Cieslik in design, and Betsy Blumenthal, the copy editor.
Trademark Notices Throughout the text we have used several trademarks. Rather than insert
a trademark symbol with each mention of the trademarked name, we
acknowledge the trademarks here and state that they are used with no
intention of infringing upon them. Other product names, trademarks, and
registered trademarks are the property of their respective owners.
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