Offline routing and spectrum allocation algorithms for elastic optical networks

Elastic optical networks (EONs) have emerged as a promising solution for future high speed networks because of their ability to efficiently manage network resources and provide better spectrum utilization to cope with the recent rapid change in traffic behavior and the tremendous growth in bandwidth demand. The routing and spectrum allocation (RSA) problem is one of the key challenges for the effective design and control of EONs. Recently, the offline RSA problem has been mapped to a multiprocessor scheduling problem and solved using a well-known list scheduling heuristic. In this paper, we address an RSA multiprocessor scheduling formulation with the objective of minimizing the total amount of spectrum needed to serve the traffic demand in chain and mesh networks. The quality of the solution using list-scheduling algorithms is very sensitive to the ordering of the tasks in the list. We propose four list-ordering algorithms (the longest then widest compact algorithm, area compact algorithm, longest then left edge compact algorithm, and area then left edge compact algorithm) to enhance the performance of an existing list-scheduling algorithm called the compact scheduling algorithm. Our proposed algorithms are based on the left edge algorithm and the combination of the problem dimensions (i.e., the bandwidth and links). We evaluate the performance and the efficiency of our proposed algorithms across a range of demand distributions for two different network topologies (i.e., chain and National Science Foundation networks).Experimental results show that our algorithms outperform existing algorithms and provide close to optimal solutions, which are within 1–2% of the lower bound.