Road Map -- Organization of the Book

This book is organized into four parts -- Introduction, Broadcast (Local) Optical Networks, Wavelength-Routed (Wide-Area) Optical Networks, and Potpourri -- and each part contains between two and five chapters. Each part, as well as each chapter, has been organized as a ``stand-alone'' entity so that the interested and/or advanced reader can directly go to the part or chapter that is of interest. The contents of each chapter include discussion of theories as well as highlights on prototype implementations/demonstrations, wherever appropriate.

Part I consists of this chapter and the next which deals with enabling technologies, viz., the building blocks for constructing WDM networks. Chapter 2 is essentially a summary of the physical aspects of WDM systems, and is written from the point of view of a computer scientist/engineer. For further details on WDM device technologies, the reader should consult a book that exclusively deals with these topics, e.g., [Gree93">]. Readers familiar with device technologies and wishing to study WDM network architectures could skip Chapter 2.

Part II -- Broadcast (Local) Optical Networks -- contains five chapters. Its first two chapters -- Chapters 3 and 4 -- examine single-hop network architectures and protocols. While Chapter 3 provides breadth of discussion on single-hop networks, a particular single-hop protocol -- the IBM Rainbow protocol, which has also been prototyped -- is discussed and analyzed in depth in Chapter 4. The corresponding breadth and depth treatment of multihop networks is provided in Chapters 5 and 6, respectively; the multihop network analyzed in depth in Chapter 6 is called GEMNET. Chapter 7 examines a novel concept called ``channel sharing,'' and studies how it can be used to support multicasting -- the ability to transmit information from a single source node to multiple destination nodes -- in a passive-star-based optical network.

Part III -- Wavelength-Routed (Wide-Area) Optical Networks -- also consists of five chapters. Section 1.3.1 introduced the concept of a lightpath. The set of lightpaths in a wavelength-routed network forms a ``virtual topology,'' (1) which may be operated as a ``virtual Internet,'' viz., a packet-switched electronic overlay on top of the WDM optical layer; (2) which may be optimized based on prevailing traffic conditions; and (3) which may be reconfigured on demand when the pattern of offered traffic changes. Such topics related to optimal virtual topology design are studied in Chapters 8 and 9. Chapter 10 deals with the solution to the Routing and Wavelength Assignment (RWA) problem outlined earlier in this chapter (Section 1.3.1). Chapter 11 examines the issues related to wavelength conversion, reviews several approaches, and reports on a simulation-based study on ``sparse wavelength conversion'' under which conversion capabilities (which are costly) are sparsely sprinkled through the network. Chapter 12 reviews other work and results on wavelength-routed networks.

The organizing principle behind Part IV -- Potpourri -- is less strong than those for the other parts of this book, i.e., the contents of Part IV can be considered to be ``other important material in WDM networks that did not fit elsewhere.'' The first chapter (out of four) in Part IV considers a fiber-optic ring network such as a SONET ring or a Fiber Distributed Data Interface (FDDI) network, and examines how to incorporate ``growth capability'' in such a network by operating it over multiple wavelengths; corresponding optimized partitioning problems to operate the network over multiple subnetworks are defined and analyzed. The next two chapters in Part IV -- Chapters 14 and 15 -- however, do possess a reasonably cohesive theme, viz., they attempt to address topics at the ``device-network interface''; specifically, these chapters examine the not-so-desirable properties of optics, and try to correct for these ``mismatches'' using intelligent networking algorithms. The final chapter -- Chapter 16 -- deals with optical TDM and CDM networks.

Problem sets are included at the end of each chapter. There are two appendices containing (1) information on further reading, and (2) a glossary of important terms. Finally, all citations are included in a common bibliography at the end of the book.