Hop Based Protection: A protection solution for heavily loaded WDM optical networks

Survivability of an optical network can be defined as the ability of the network to continue its services after the occurrence of the failures. With the increase in size and complexity, issues related to survivability become paramount important. Most of the previous studies have addressed the survivability for low traffic loads. However, extensive use of Internet applications make network heavily loaded. Hence in this paper, we propose a scheme for heavily loaded WDM networks which uses resources in an efficient manner. In the proposed scheme, protection for connection request is provided in accordance with path length (communication distance between source destination pair in terms of hop counts) of the connection request. For short path length connection requests no protection is considered, for moderate path length shared path protection is considered, and for long path length we provide dedicated path protection. It means that proposed algorithm gives highest priority to long path length requests (may be international calls or long distance calls) in terms of service without interruption. Moderate (calls within a territory) and short path length requests (calls within the city viz. local calls) are assigned moderate and least priorities respectively. Since long distance call charges are highest among all categories hence results in better revenue profit to service provider. Simulation results show that for heavy traffic load, the proposed scheme exhibits low blocking probability and low wavelength utilization ratio as compared to existing well known scheme.