Service and restoration routing and wavelength assignment and restoration signaling in optical networks.

摘要

The objective of this dissertation is to develop efficient solutions for routing and restoration of lightpaths in a circuit-switched wavelength division multiplexed (WDM) network. Such a network is fundamentally important to the success of a next-generation Internet which will have the capacity to carry a much larger amount of traffic than today's Internet at lower delays.; This dissertation aims to contribute to optical layer design by improving the fault tolerance of the optical network architecture through efficient algorithms to restore lightpaths in the event of link failures. These algorithms not only utilize the network resources, namely wavelengths, efficiently, but also provide rapid restoration capability.; The first part of this work, presented in [42, 39, 41], focuses on capacity provisioning for service and restoration in a WDM optical network which provides lightpaths to higher layer networks. An optical network will likely serve several client networks with different protection requirements from the optical layer. In this dissertation, a framework is developed for jointly assigning wavelengths to service and restoration paths for all failures, for traffic patterns with single or multiple classes of protection. For various restoration methods, the problem is reduced to a vertex coloring problem in a graph. Using this framework, we present routing and wavelength assignment (RWA) algorithms for service and restoration with varying capacity/restoration time tradeoffs, and evaluate their performance through simulations. We consider three classes of lightpaths in terms of protection requirement: protected lightpaths, unprotected lightpaths, and low-priority lightpaths. We then consider WDM ring networks, and derive bounds to the wavelength requirement for service and restoration under different restoration methods. We also present an efficient service/restoration RWA algorithm, which simplifies fault-monitoring and reduces hardware requirement through judicious wavelength assignment. Through simulations and comparisons with the bounds, we show that these advantages can be obtained without significant increase in the wavelength requirement.; The second part of our work focuses on the restoration signaling aspect of the problem. We present signaling protocols for various restoration methods discussed in the first part, and evaluate their performance in terms of restoration speed and restorability. (Abstract shortened by UMI.)