Segment-Based Partial Protection Scheme for Routing Reliability Guaranteed Connections in WDM Optical Networks

n this paper, we consider the reliability of a connection as a parameter to denote different levels of fault- tolerance and propose a segment-based partial protection scheme for routing reliability-guaranteed connections in a resource efficient manner. In this scheme we try to provide a partial protection path instead of an end-to-end protection path to improve the reliability of a connection. To provide partial protection path, we need to identify primary segments which are less (more) reliable (vulnerable) to failures and select a suitable primary segment to provide a protection segment. However, identifying less-reliable primary segments which really contribute to achieve the required reliability and selection of resource-efficient protection segment among several possible segments are not trivial problems. In this paper, we develop efficient methods to address these problems. Apart from providing the reliability guarantee, the proposed scheme is able to recover all failures immediately, except the failures which are not covered by the protection segment. In this case the failed connections cannot be rerouted on to the protection segment and we initiate our proposed recovery process which handles all possible failure scenarios. We conduct extensive simulation experiments to evaluate the effectiveness of the proposed scheme on different network configurations with respect to three performance metrics: average spare wavelength usage, average recovery time, and average recovery ratio.