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Review Essays of Academic, Professional & Technical Books in the Humanities & Sciences


Mesh-based Survivable Transport Networks: Options and Strategies for Optical, MPLS, SONET and ATM Networking by Wayne D. Grover (Prentice Hall PTR )"Internet hindered by severed cable." "Internet chaos continues today... " "Cable break disrupts Internet in several countries. " "Calling and major businesses down from cable cut. "

These are headlines arising in just one month from fiber optic cable disruptions. Despite the enormous advantages of fiber optics and wave-division multiplexing, the truth is that the information economy-fueled by fiber-optic capacity-is based on a surprisingly vulnerable physical medium. Every effort can be made to protect the relatively few thumb-sized cables on which our information society is built, but the cable-cuts and other disruptions just don't stop. From deep-sea shark bites to the fabled "backhoe fade," serious transmission outages are com­mon and of increasing impact. Some form of fast rerouting at the network level has become essential to achieve the "always on" information networks that we depend upon.

One way to survive optical network damage is to duplicate every transmission path. In the form of rings and diverse-routed protection switching schemes, this is actually the most wide­spread solution in use today. Our view has long been that this is an inefficient expedient-the "get a bigger hammer" approach to solving a problem. Admittedly, rings filled the void when survivability issues reached crisis proportions in the 1990s. But now network operators want options that are just as survivable but more flexible, more growth-tolerant, able to accommodate service differentiation, and far more efficient in the use of capacity. This is where "shared­mesh" or "mesh-restorable" networks take the stage.

The author's love affair with the mesh-survivability approach began in 1987-with the naive certainty back then that sheer elegance and efficiency would suffice to see it adopted in SONET by 1990! The actual journey has been much longer and complicated than that. The Internet and Optical Networking had to happen first. And all the ideas had much more develop­ment to undergo before they would be really ready for use. Today, we understand the important values of mesh-based survivability go beyond just efficiency (and of course you can rarely make money off of elegance alone). Flexibility, automated provisioning, differentiated service capa­bilities, and the advent of Internet-style signaling and control are all important in making this a truly viable option. But its full exploitation still requires new concepts and ideas about network operation-letting the network self-organize its own logical configuration, for example, and let­ting it do its own preplanning and self-audit of its current survivability potential. New planning and design models are also required. These are the central topics of this book-designed to stim­ulate and facilitate the further evolution toward highly efficient, flexible and autonomous mesh­based survivable networks.

The book is written with two main communities in mind. One is my colleagues in indus­try; the system engineers, research scientists, technology planners, network planners, product line managers and corporate technology strategists in the telcos, in the vendor companies, and in corporate research labs. The are the key people who are continually assessing the economics of new architectural options and guiding technology and standards developments. Today these assessments of network strategy and technology selection put as much emphasis on operational expense reduction as on capital cost-capacity efficiency and flexibility are both important in future networks. Network operators are in an intensely competitive environment with prices dropping and volumes rising and success is dependent on all forms of corporate productivity enhancement. Mesh networking can provide fundamental productivity enhancements through greater network efficiencies and flexibility. The book aids the operating companies in finding these new efficiencies by giving many new options and ideas accompanied with the "how to" information to assess and compare the benefits on their own networks. Examples of the new directions and capabilities the book provides are in topology evolution, ring-to-mesh conversion by "ring-mining," multiple Quality-of-Protection design, tailoring restoration-induced packet congestion effects in a controlled manner, simplifying dynamic demand provisioning, and so on. An important plus is that the book also contains the first complete treatment of the intriguing and promising new concept called "p-cycles"-offering solutions with ring-speed and mesh­efficiency.

Providers of the networking equipment, the vendors, are-as the saying goes-"fasci­nated by anything that interests their boss." That means their network operating customers. Vendors must not just keep in step with the problems, opportunities, and thinking of their customers, but also aspire to bring their own unique equipment design strategies to the market and to pro­vide leadership in development of advantageous new networking concepts. The vendor commu­nity will therefore be especially interested in the techniques for split-second mesh restoration and self-organizing traffic-adaptation as features for their intelligent optical cross-connects and Gigabit routers, for instance-as well ideas for new transport equipment such as the straddling span interface unit that converts an existing add/drop multiplexer into a p-cycle node. All of the other topics covered are of interest to vendors too because they enhance their ability to assist customers with network planning studies as part of the customer engagement and sales process.

Developers of network modeling, simulation and planning software will also be interested in many ideas in the book. By incorporating capabilities to design all types of architecture alter­natives or, for example, to simulate dynamic provisioning operations in a protected working capacity envelope, or to model the incremental evolution of a survivable capacity design in the face of uncertain demand, or to support ring-mining evolutionary strategies-these suppliers enable their customers to pursue a host of interesting new "what if' planning studies.

The second main community for whom the book is intended is that of graduate-level teaching and research and new transport networking engineers who want a self-contained vol­ume to get bootstrapped into the world of transport networking planning or to pursue thesis-ori­ented research work. A principle throughout has been to draw directly on my experience since 1992 at the University of Alberta of teaching graduate students about survivable transport net­working. This allowed me to apply the test: "What needs to be included so that my graduate stu­dents would be empowered both to do advanced investigations in the area, but also to be knowledgeable in general about transport networking?" On one hand, I want these students to be able to defend a Ph.D. dissertation, but on the other hand also to have enough general awareness of the technology and the field to engage in discussion with working engineers in the field. This is really the reason the book has two parts.

The test of needed background has guided the definition of Chapters 1 to 4 which are called the "Preparatory" chapters. These chapters cover a lot of generally useful ground on IP and optical technology, routing algorithms, graph theory, network flow problems and optimiza­tion. Their aim is to provide a student or new engineer with tools to use, and an introductory understanding of issues, trends, and concepts that are unique to transport networking. In my experience, students may have done good theoretical research, but at their dissertations a com­mittee member may still stump them with a down-to-earth question like "How often do cables actually get cut?" "Is this just for SONET or does it work for DWDM too?", "How does restorability affect the availability of the network?" or (perennially it seems) "...but I don't see where are you rerouting each phone call or packet." These few examples are meant just to con­vey my philosophy that as engineers we should know not only the theory, the mathematical methods, and so on, to pursue our "neat ideas" but we also need to know about the technology and the real-world backdrop to the research or planning context. This makes for the best-pre­pared graduate students and it transfers to the training of new engineers in a company so that they are prepared to participate and contribute right away in all discussions within the network planning group he or she joins. An engineer who can, for example, link the mathematics of availability analysis to a contentious, costly, and nitty-gritty issue such as how deep do cables have to be buried, is exactly the kind of valuable person this book aims to help prepare. Some­one who can optimize a survivable capacity envelope for mixed dynamic services, but is also savvy enough to stay out of the fruitless "50 ms debate" is another conceptual example of the complimentary forms of training and knowledge the book aspires to provide.

The book is ultimately a network planners or technology strategists view of the network­ing ideas that are treated. It employs well-grounded theoretical and mathematical methods, but those are not the end in itself. The book is also not filled with theorems and proofs. The empha­sis is on the network architectures, strategies and ideas and the benefits they may provide, not primarily on the computational theory of solving the related problems in the fastest possible way. Our philosophy is that if the networking ideas or science look promising, then the efforts on computational enhancement are justified and can follow. Fundamental questions and ideas about networks, and network architecture, (which is the main priority in my group) stand on their own, not to be confused with questions and ideas about algorithms and solution techniques to solve the related problems as fast as possible (others are stronger in that task). Obviously work in this area involves us in both networking science and computation, but the logical dis­tinction is important-and often seems lost in the academic literature. The book is also not a compendium or survey of previously published papers. While suitably referenced, its content is unabashedly dominated by the author's own explorations and contains a large amount of previ­ously unpublished material. Although setting the context in terms of modem transport technolo­gies (WDM, SONET, ATM, IP, MPLS) our basic treatment of the networking ideas and related planning problems is in a generic logical framework. The generic models can be easily adapted for to any specific technologies, capacities, costs, or signaling protocols, etc. The book thus pro­vides a working engineer or a new researcher with a comprehensive, theoretically based, refer­ence book of basic architectural concepts, design methods and network strategy options to be applied on mesh-survivable networks now and in the future.

A few words about the flow of the book. The Introduction gives a much fuller roadmap of the content and novelty in each chapter. Briefly, however, Chapter 1 is an orientation to trans­port networking. Chapter 2 is devoted to background on IP and DWDM optical networking developments, as the technological backdrop. Part of Chapter 3 is partly just "interesting reading" on the effects of failures and the range of known schemes and techniques to counteract or avoid failures. The rest of Chapter 3 includes a more technical "sorting out" of the "-ilities": availability, reliability, network reliability, restorability, and other measures. Chapter 4 is then devoted to graph theory, routing algorithms and optimization theory and techniques but only as these topics specifically relate to transport network problems. Chapter 5 starts the second part of the book on more advanced studies and applications with an in-depth treatment of span protec­tion and restoration. It has its counterpart devoted to path restoration in Chapter 6. Chapter 5 considerably "updates" the thinking about span-oriented survivability in optical networks with dynamic traffic.

If the book was a musical score, Chapters 7 through 11 would be the "variations." Each chapter treats a more advanced topic or idea selected by the author because of its perceived use­fulness or possible influence on the direction of further research and development. These are some of the author's "shiny pebbles" (in the earnestly humble sense of Newton). Chapter 7 rec­ognizes an important difference-and opportunity-in cell or packet-based transport: that of controlled oversubscription of capacity upon restoration. This is a unique advantage for MPLS/ IP-based transport survivability. Chapter 8 is devoted to all aspects of dual-failure consider­ations in mesh restorable networks. An especially interesting finding is that with a "first-failure protection, second-failure restoration" concept, higher than I+ 1 availability can be achieved for premium service paths at essentially no extra cost. Chapter 9 treats the challenging, and so far almost unaddressed, problem of optimizing or evolving the basic facility-route (physical layer) topology for a mesh-restorable network. Chapter 10 explains the new (and to us, very exciting) concept of p-cycles, which are rooted in the idea of pre-configuration of mesh spare capacity.

p-Cycles are, in a sense, so simple, and yet they combine the fast switching of ring net­works with the capacity-efficiency of mesh-based networks. We include p-cycles as a mesh­based survivable architecture because they exhibit extremely low mesh-like capacity redun­dancy and because demands are routed via shortest paths over the entire facilities graph. They are admittedly, however, a rather unique form of protection scheme in their own right in that lies in many regards in-between rings and mesh. Candidly, I venture that many colleagues who went through the decade-long ring-versus-mesh "religious wars" of the 1990s would understand when I say that p-cycles call for that forehead-bumping gesture of sudden realization-this solution (which combines ring and mesh) was unseen for the whole decade-long duration of this debate! As of this writing the author knows several research groups that are shifting direction to work on p-cycles as well as a half-dozen key industry players looking closely at the concept.

Chapter 11 on ring-mesh hybrids and ring to mesh evolution is placed at the end. The logic is that if we assume success of the prior chapters in motivating the mesh-based option then the "problem" this creates is that many current networks are ring-based. Its like "Ok, we believe you-but how do we get there now?" The closing chapter therefore devotes itself to bridging the gulf between existing ring-based networks and future mesh or p-cycle based networks by con­sidering the design of intermediate ring-mesh hybrid networks and "ring-mining" as a strategy to get to a mesh future from a ring starting-point today.

The Appendices, and other resources such as chapter supplements, a glossary, student problems, research project ideas, network models, and more are all web-based-so they can be continually updated and expanded in scope and usefulness. Many directly usable tools and resources are provided for work in the area of mesh-survivable networking. This includes AMPL models and programs to permit independent further study of most of the planning strate­gies presented, plus Powerpoint lectures on a selection of topics, technical reports, and addi­tional references and discussions. The aim has been to create a highly useful and hopefully interesting book that is laden with new options, ideas, insights and methods for industry and aca­demia to enjoy and benefit from.

Third Generation CDMA Systems for Enhanced Data Services by Giridhar D. Mandyam, Jersey Lai (Communications, Networking and Multimedia: Academic Press) First book to cover both of the leading CDMA standards and it provides an authoritative, current review of the newest third generation technologies. Ideal for engineers developing wireless devices, as well as for those in the service sectors.
Until now, most wireless devices have been used for voice transmission, but the new third generation of wireless devices promise greatly enhanced delivery of both voice and data communications. These devices are currently under development and are being built using the two major CDMA (code division multiple access) systems, cdma2000 and wideband CDMA. These telecommunication systems use signal codes to receive voice and data information. This authoritative new book reviews both of these systems and deals with the challenges engineers face in bringing these next generation devices to market. The authors work at Nokia, one of the world's leading companies involved with the design, development, and manufacture of wireless telephones and devices. They are closely involved within Nokia and the industry in working with CDMA standardization to bring this technology to the consumer. This is the first book to cover both of the leading CDMA standards (cdma2000 and wideband CDMA), and it provides an authoritative, current review of the newest third generation technologies. This book is ideal for the engineers developing wireless devices (at Nokia, Ericsson, Qualcomm, Motorola, etc.), as well as for those in the service sectors (i.e. AT&T, Verizon, Voicestream, Quest, etc.).

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