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This chapter is from the book


This chapter provided the "big picture" of the WDM optical networks. As mentioned earlier, this book focuses on wavelength routed (wide area) optical networks. In this chapter we introduced several issues concerning the design of these networks. The rest of the book addresses some of these issues in depth and is organized into eight chapters followed by a bibliography and appendices.

Chapter 2 deals with the problem of routing and wavelength assignment (RWA). It first presents different methods for route selection and wavelength selection with illustrations and then describes several important RWA algorithms in detail with suitable examples. It also presents distributed control protocols for wavelength routing and several solutions for the connection fairness problem which arises as longer-hop connections are more likely to be blocked (rejected) compared to shorter-hop connections.

Chapter 3 deals with wavelength-convertible networks. It first highlights the benefit of employing wavelength converters and then explains different wavelength-convertible switch architectures. It then presents a routing algorithm in convertible networks and some analytical models which predict the performance of these networks. It also addresses converter placement and converter allocation problems.

Chapter 4 deals with wavelength rerouting algorithms to improve wavelength channel utilization. It first describes several lightpath migration operations and then presents several algorithms for wavelength rerouting in single-fiber and multi-fiber networks with and without wavelength conversion. It also analyzes the computational complexity of these algorithms.

Chapter 5 deals with the problem of virtual topology design, which is an important and challenging one. It first discusses the limitations on choosing the best possible virtual topology and then explains the different virtual topology design subproblems with necessary illustrations. It also presents a mixed-integer linear programming formulation of the virtual topology design problem, and several heuristic solutions for the problem and its variants with suitable examples. It finally introduces the problem of designing multifiber networks and also presents a solution for this problem.

Chapter 6 deals with the problem of virtual topology reconfiguration. It first presents several schemes to reconfigure the existing virtual topology in response to a change in the traffic. It then discusses the exact solution methods and also several heuristic methods for reconfiguring a virtual topology. It also presents an approach to reconfigure a virtual topology when a network component fails.

Chapter 7 deals with the problem of network provisioning and survivability. It presents a classification of lightpath restoration methods which are employed to reroute affected traffic upon a network component failure. It also presents an integer linear programming formulation of the survivable network design problem, and it discusses several algorithms for designing survivable networks. It finally explains survivability mechanisms in WDM ring networks.

Chapter 8 deals with optical multicast routing. It first describes architecture of multicast-capable switches which help in carrying out multicast routing in an efficient way. It then presents several algorithms for multicast routing in networks with full and sparse splitting capabilities.

Chapter 9 deals with three different WDM technologies: circuit switching, burst switching, and packet switching, that are likely to be adopted in the next-generation Internet networks. It presents different protocol stack options and packet encapsulation and framing techniques that can be used for transporting IP traffic over the WDM (optical) layer. It then presents an architecture and protocols for optical burst switching networks. It also describes a burst switching protocol to support differentiated services. It then explains two switch architectures and contention resolution techniques for optical packet switching networks. It finally explains how the traditional IP/MPLS framework can be extended to WDM-based optical networks.

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