Investigation of physically aware routing and wavelength assignment (RWA) algorithms for next generation transparent optical networks

Abstract

Optical networks form the foundation of today's information infrastructure. Current generation optical networks consist largely of point-to-point electronically transmitted links which switch between nodes and repeaters. There is a trend in optical networking to move from the current generation opaque networks toward transparent networks. Transparent networks use only optical devices, eliminating the costly need for OEO conversions. Unfortunately, transparent networks present a unique challenge in maintaining acceptable signal quality levels. This research is an investigation of RWA algorithms in transparent optical networks. We present RAPTOR, a custom built discrete event program to simulate optical networks. RAPTOR uses its physically aware modules to accurately calculate three of the dominant physical impairments. RAPTOR is fast and multi-threaded. We introduce several new performance metrics. RAPTOR enables us to study transparent optical networks in a unique and realistic manner. We conduct an extensive performance analysis of existing RWA algorithms. We explore many different traffic models, traffic loads, signal quality, and network topologies in a comprehensive fashion. We directly compare the leading RWA algorithms in a manner has not been done before. We studied new RWA algorithms in two fields: Dynamic Programming and Ant Colony Optimization. Our new Dynamic Programming based algorithm has the best overall performance in most scenarios. It is flexible and adapts well to all network conditions we studied. It shows good promise for future optical networks.