On Modeling the Restoration Probability of Active Restoration-Based Optical Networks with Correlation Among Backup Routes

Active restoration (AR) is a novel lightpath restoration scheme proposed recently to guarantee a certain degree of survivability in WDM optical networks with a reasonable tradeoff between capacity requirement and restoration time. An analytical model has been proposed to analyze the restoration probability behavior of a connection request in optical networks employing AR based on the assumption that all the backup routes of the connection are independent. In a real AR-based optical network, however, the backup routes of a connection are likely to be correlated since they may share some common links along their routes. Therefore, an analytical approach was proposed recently to model the restoration probability of the connection by considering all the possible correlation between any two of its successive backup routes. Although the proposed approach achieves better approximation to the restoration probability, it overestimates the restoration probability of the connection when its non-successive backup routes are being correlated. However, considering all the possible correlations among backup routes is computationally Intractable. In this paper, we conduct a comprehensive performance analysis for AR-based optical networks. In particular, we propose a novel analytical framework for modelling the restoration probability of a connection when the possible correlations among any three successive backup routes are fully incorporated.