Preface

The Topic

Research and development on optical WDM networks have matured considerably over the past few years, with a number of commercial WDM products already available. A number of different experimental prototypes have been and are being deployed and tested in the U.S., Europe, and Japan, with significant support from their respective government agencies and telecommunication providers. There now exists a large and expanding interest on this topic to better understand the issues and challenges in designing such networks. It is anticipated that the next generation of the Internet will employ WDM-based optical backbones.

Intended Audience

I expect that instructors will find the book useful for teaching a graduate course on this subject. The book has been ``class tested" in a one-quarter graduate course, ECS 289I, ``Optical Communication Networks," which I taught at my home institution, University of California, Davis, during Winter Quarter 1997. As a result, the book has been ``debugged" significantly, including the creation of most of the end-of-chapter exercises.

Since the major developments in optical communication networks have started to capture the imagination of the computing, telecommunications, and opto-electronic industries, I expect that industry professionals will find this book useful as a well-rounded reference. Through my own consulting work, I find that there exists a large group of people who are experts in physical-layer optics, and who wish to learn more about network architectures, protocols, and the corresponding engineering problems in order to design new state-of-the-art optical networking products. This group of people is also who I had in mind while developing this book.

Organization Principles and Unique Features

This book is *not* intended to cover in any detail the physical-layer aspects of optical communications; readers should consult an appropriate book, e.g., [Gree93], for such material. We summarize these ``enabling technologies" in a single chapter (Chapter 2). Our treatment of the material in this chapter should allow us to uncover the unique strengths and limitations of the appropriate technologies, and then determine how the characteristics of the physical devices may be exploited in pragmatic network architectures, while compensating for the device limitations or ``mismatches".

An important organizing principle that I have attempted to keep in mind while developing this book is that research, development, and education on optical communication networks should allow tight coupling between network architectures and device capabilities. To date, research on optical network architectures has taught us that, without a sound knowledge of device capabilities and limitations, one can produce architectures which may be unrealizable; similarly, research on new optical devices, conducted without the concept of a useful system, can lead to sophisticated technology with limited or no usefulness.

The book is organized into four parts. Part I introduces WDM and its enabling technologies. Parts II and III are devoted to WDM local-area and WDM wide-area network architectures, respectively. Part IV discusses a number of problems that address tight coupling between device capabilities/limitations and the corresponding networking challenges; Part IV also includes a chapter that briefly discusses optical time-division multiplexing (TDM) and optical code-division multiplexing (CDM). The appendices on ``where to learn more" and a ``Glossary of Important Terms" should also be beneficial to many readers. More details on the book's organization can be found in Section 1.7.

The most unique feature of this book is its timeliness to fill a void in an important and emerging networking topic. Other major salient aspects of the book are its breadth of coverage, depth of analytical treatment, clear identification of recent developments and open problems, review of testbeds and implementation efforts, an extensive bibliography (292 references), an extensive number of end-of-chapter exercises (a total of 229), an extensive set of illustrations (207 figures, 26 tables), etc.

A solutions manual is currently being developed. Instructors may obtain a copy from the publisher. Please see additional web-based features below.

Web Enhancements

• table of contents,
• list of figures,
• color versions of some figures -- some of the figures were drawn originally in color, and the color versions may be more informative than the black-and-white versions appearing in the book,
• Chapter 1 in its entirety,
• introductory material for the other chapters,
• posting of corrections, revisions, updates, etc.,
• easy mechanism for readers to provide feedback to the author and the publisher, and
• if and when possible, additional material as deemed useful, e.g., simulations for some single-hop protocols, multicasting, virtual-topology embedding, etc.; allowing animation and remote operation of simulations via parameter selection by the user using Java.

Acknowledgements

Much of the book's material is based on research that I have conducted over the years with my graduate students and research scientists visiting my laboratory, and I would like to acknowledge them as follows: Dhritiman Banerjee for the wavelength-routing material (Chapters 8-10, 12); Mike Borella for the enabling-technologies review (Chapter 2); Debasish Datta for optical TDM (Chapter 16); Jason Iness for GEMNET, sparse wavelength conversion, optical-cycle elimination, and amplifier placement (Chapters 6, 11, 14, 15); Jason Jue for enabling technologies, RAINBOW analysis, and optical CDM (Chapters 2, 4, 16); Byrav Ramamurthy for wavelength conversion, cycle elimination, and amplifier placement (Chapters 2, 11, 14, 15); S. Ramamurthy for wavelength routing and WDDI (Chapters 8, 12, 13); and Srini Tridandapani for channel-sharing and multicasting (Chapter 7).

A number of additional individuals who I have collaborated with over the years, who have enabled me to better understand the subject matter, and who I would like to acknowledge are the following: Krishna Bala, Subrata Banerjee, Chuck Brackett, Kamal Goel, Jon Heritage, Feiling Jia, and Behzad Moslehi.

I would like to thank the following Winter97 ECS 289I students who ``debugged" the book and who provided many of the end-of-chapter problems: Steven Cheung, Bill Coffman, Jason Jue, Arijit Mukherjee, Raja Mukhopadhyay, Vijoy Pandey, Byrav Ramamurthy, S. Ramamurthy, Laxman Sahasrabuddhe, Feng Wang, and Raymond Yip. Murat Azizoglu and Debasish Datta also contributed several problems, while Jason Jue and Laxman Sahasrabuddhe ``organized" these exercises; their efforts are highly appreciated.

Special thanks are due to Byrav Ramamurthy for the book's ``electronic organization," several figure drawings, and answers to my LaTeX2e questions; and to Ken Victa for developing the graphical user interface (GUI) to visualize and draw the results of our optimization studies.

This book wouldn't have been possible without the support of my research on optical communication networks from several funding agencies as follows: National Science Foundation (NSF) (Grant Nos. NCR-9205755, NCR-9508239, and ECS-9521249); Defense Advanced Research Projects Agency (DARPA) (Contract Nos. DABT63-92-C-0031 and DAAH04-95-1-0487); Air Force Office of Scientific Research (AFOSR) (Grant No. 89-0292); Pacific Telesis; Optivision, Inc.; and University of California MICRO Program.

Quality control for a book can be ensured through independent technical reviews. In this regard, the following reviewers are deeply appreciated for their time, effort, suggestions for improvement, and feedback on the book's manuscript and/or its initial proposal: Murat Azizoglu, Andrea Fumagalli, Anura Jayasumana, Walter Kahn, and Arun Somani.

I wish to acknowledge the people at McGraw-Hill who I interfaced with -- Steven Elliott and David Fogarty -- for their encouragement and attention to detail during the book's production. The book's camera-ready version was produced by the author using the LaTeX2e document-processing system.

Finally, I wish to thank my family members for their constant encouragement and support: my father Dhirendranath Mukherjee, my mother Gita Mukherjee, my wife Supriya, my daughters Bipasha and Suchitra, and my brother Amarnath. I couldn't have done it without you!

I welcome email from readers who wish to provide any sort of feedback: errors, comments, criticisms, and suggestions for improvements.