LAUSR

Abstract In this paper, a reactive defragmentation rerouting and spectrum assignment (RDRSA) strategy when existing connection requests terminated and network resources released is presented. In RDRSA with spectrum conversion (SC), the existing connections are re-established to new route or reassigned to new frequency slots. Defragmentation has three advantages over the conventional RSA: (1) at the time of connection setup, shorter routes may be unavailable, but after the termination of the existing requests; possibility of re-assignment of shorter route becomes high, (2) fragmentation of network also reduces which results load balancing over the entire network, (3) network resource utilization increases due to more connection acceptance. The performance of RDRSA-SC is compared with the conventional RSA with spectrum conversion (SC), and non spectrum conversion (NSC). The simulation results on NSFNET and ARPANET network topologies show that the proposed RDRSA-SC has lower fragmentation and bandwidth blocking probability, and more utilization of network capacity than the existing RSA-SC and RSA-NSC.