Differentiated reliability in wavelength division multiplexing networks

Current optical networks typically offer two degrees of service reliability: full protection in presence of a single fault in the network, and no protection at all. This situation reflects the historical duality that has its roots in the once divided telephone and data environment. The circuit oriented service requires protection, i.e., provisioning of readily available spare resources to replace working resources in case of a fault. The datagram oriented service relies upon restoration, i.e., dynamic search for and reallocation of affected resources via actions as routing table updates.; The current development trend, however, is gradually driving the design of networks towards a unified solution that will jointly support traditional voice and data services as well as a variety of novel multimedia applications. The growing importance of concepts, such Quality of Service (QoS) and Differentiated Services—that provide multiple levels of service performance in the same network—evidences this trend. Consistently with this pattern, the concept of Differentiated Reliability (DiR) is formally introduced in this dissertation and applied to provide multiple reliability degrees (or classes) in the same network layer using a common protection mechanism, i.e., path switching. According to the DiR concept, each connection in the layer under consideration is guaranteed a minimum reliability degree, or equivalently a maximum failure probability allowed for that connection. The reliability degree chosen for a given connection is thus determined by the application requirements, and not by the actual network topology, design constraints, robustness of the network components, and span of the connection.; In this dissertation the concept of DiR is applied to various Wavelength Division Multiplexing (WDM) network topologies. The analysis is carried over a number of alternative protection schemes, i.e., shared path switching and dedicated path switching. Formal problem definitions are provided and efficient algorithms to solve the various problems are designed. The goodness of the proposed algorithmic solutions is assessed and the trade-offs between reliability and network costs are quantitatively analyzed. Additionally the feasibility of the DiR concept based on the shared path protection scheme has been proven to be feasible on an all-optical test-bed.