Abstract
Survivability is the ability of the network to continue operating in the event of failure. Lightpath restoration is a cost efficient approach to guaranteeing certain degree of survivability in WDM optical networks and active restoration (AR) is a novel lightpath restoration scheme proposed recently. In this paper, we study the performance of AR. In particular, we develop analytical models for approximating the restoration probability for circuit-switched WDM networks employing AR scheme. Extensive simulations have been conducted to verify the proposed models. The simulation results show clearly that our models are quite efficient for approximating the restoration probability for WDM networks employing active restoration.