Abstract
Fixed alternate routing is a potential routing scheme for routing and spectrum allocation (RSA) in elastic optical networks (EON) which has less complexity and time consumption compared to adaptive routing scheme. However, adaptive routing scheme efficiently reduces the amount of network bandwidth blocking probabilities (BBPs) which uses traffic engineered paths and tunes according to the current network status. In this paper, an algorithm for routing is proposed for dynamic traffic in EON which works iteratively to arrange the pre-computed fixed alternate routes offline to incorporate link loading. During the offline process, the pre-computed routes are arranged with an objective to reduce link congestion and diverts lightpaths to the under-utilized links. The proposed scheme merges the properties of fixed alternate routing and adaptive routing and is utilized for dynamic traffic in EON. It has been shown through simulation results that the proposed scheme efficiently improves the performance of RSA in EON and reduces the amount of BBPs compared to the fixed alternate routing and an existing constrained-lower-indexed-block (CLIB) based adaptive routing algorithm. The proposed LCA greatly reduces congestion over all links during dynamic network operation and lowers congestion spikes over some links which occues in the existing alternate routing scheme in different network scenarios.