A path-disjoint approach for blocking probability analysis in hybrid dynamic wavelength routed WDM grooming networks

The present article addresses a novel approach to enhance the overall performance of a WDM optical network. Centralized and distributed approaches for dynamic lightpath establishment are well studied in the literature. Both the approaches have some drawbacks. In this article a hybrid approach is proposed to accept the advantages and discard the disadvantages of both the approaches. With the proposed hybrid approach, a WDM optical network is divided into clusters of nodes. Within a cluster centralized mechanism is applicable whereas connection requests between the node pairs from different clusters follow the distributed mechanism. Also, in this article an analytical model is proposed to compute the expected blocking probability of the proposed hybrid network. First, blocking probabilities for the centralized and distributed approaches are computed and then it is extended for the hybrid approach. The distinguished feature of the proposed analytical model is that it efficiently utilizes the path information of the calls to determine the overall blocking probability of a WDM optical network. It extracts the necessary parameters of a network by simulation and utilize the information to analytically calculate the blocking probability of the network. The NSFNET T1 backbone network is used for the simulation study. To justify the analytical model, the simulation results are compared with that of the analytical model. The simulation results establish the effectiveness of the proposed hybrid approach over the distributed approach in merits of both the call setup time and blocking probability.