| In the past few decades, there has been a rapid advancement in telecommunication networks driven primarily by the explosion of new applications that have resulted in a dramatic increase in the traffic demand. Currently, optical networks utilize dense wavelength division multiplexed transmission systems, together with intelligent optical networking equipment to accommodate this demand. Optical networks must be able to provide robust and reliable end-to-end service to customers, with differentiated service level agreements. In order to guarantee these prescribed service levels, these networks need to employ a fast, efficient and reliable fault restoration approach. This is an important aspect of the network operation, as in these networks failures can occur frequently, either due to accidents, equipment malfunction, human error or even malicious attacks. The destruction of a key call and data-switching center in lower Manhattan on September 11 2001 is a clear example for the need of survivable networks.; This dissertation investigates novel optical layer restoration techniques. The problem of restoring services after a failure in the optical layer for an arbitrary mesh network has been previously examined in the context of path-based and line-based restoration. The main contribution of this thesis is a proposed framework that tries to combine the best features of both path and line based approaches in a new island-based technique. This dissertation formulates the island-based restoration architecture, develops algorithms for both identifying the islands and the working and restoration routes, and optimizes the restoration capacity allocation. It also develops and analyzes a unique island-based restoration protocol.; In today's networks that carry data, voice and video traffic, the key features of a robust restoration scheme are restoration speed, restorability and capacity efficiency. Each of these features is addressed in this thesis. The proposed island-based restoration technique and associated protocols enable the recovery of traffic from both link and equipment failures, provide restoration speeds on the order of milliseconds, minimize the exchange of restoration signaling messages and achieve efficient restoration capacity utilization. |
