Design issues in the next generation wavelength division multiplexed optical network

Resource fragmentation is one of the major problems affecting bandwidth provisioning in WDM networks. This causes longer lightpaths experience a higher blocking probability compared to shorter lightpaths. In this thesis we present a novel mechanism to mitigate this problem. We develop a Traffic Classification and Load Balancing (TCLB) algorithm that uses a cost function that incorporates waveband information in conjunction with criticality levels on a link to spread out the traffic homogenously throughout the network and mitigate the fairness problem. In addition, we show that using the TCLB algorithm with proper choice of criticality levels a lower net blocking probability can be achieved as compared to algorithms using only traffic classification.;We develop intelligent dynamic routing algorithms to route the signals considering the signal quality constraint (measured in terms of the Bit Error Rate (BER)) which is used as a measure of signal quality when routing a particular connection. By studying the network performance and signal quality we develop intelligent impairment aware algorithms to use the regenerators in an efficient manner and hence reduce the number of calls being blocked due to high BER, effectively reducing the net calls that are blocked due to poor signal quality. We also present dimensioning of the optical Cross-connect and develop policies to share the available resources (transceivers) and reduce cost at the node. To achieve optimal usage of transponders at nodes, we present three novel switching mechanisms to achieve steerability at Optical Cross-connect sites. By achieving steerability, the traffic that needs to be added/dropped at a node can be routed to any of the available transponders, thus improving the utilization of deployed transponders. We present nodal architectures that maximize system performance and deployment flexibility, while minimizing cost of sub-systems and components (like Wavelength Selective Switches, amplifiers etc.) which make up these nodes. In addition, the port dimensioning of such steerable architectures are analyzed and optimal port allocation based on the cost and loss compensation are calculated. Also the concept of Optical Reach for an optical network is explored and strategies to achieve the same are presented. We evaluate the network cost as a function of the WDM systems reach and traffic volume (wavelength fill level). The impact of various technologies on the optimal reach is discussed and novel network architectures are presented. Finally the impact of these strategies on the normalized cost of the system is studied as a function of traffic volume.