Lightpath (wavelength) routing in large WDM networks

TLDR

A lightpath is a fully optical transmission path, while a semilightpath chains several lightpaths using wavelength conversion at junctions, and this class of methods encompasses all known related practical approaches. The study addresses efficient circuit switching in wide area optical networks by proposing optimal routing of lightpaths and the novel concept of semilightpaths. A fast, practical algorithm optimally routes lightpaths and semilightpaths, accounting for link wavelength and conversion costs, and works for any physical realization of wavelength conversion. We prove that the algorithm’s running time is optimal among all algorithms that use linear algebraic operations on weights.

Abstract

We address the problem of efficient circuit switching in wide area optical networks. The solution provided is based on finding optimal routes for lightpaths and the new concept of semilightpaths. A lightpath is a fully optical transmission path, while a semilightpath is a transmission path constructed by chaining together several lightpaths, using wavelength conversion at their junctions. A fast and practical algorithm is presented to optimally route lightpaths and semilightpaths taking into account both the cost of using the wavelengths on links and the cost of wavelength conversion. We prove that the running time of the algorithm is the best possible in the wide class of algorithms allowing linear algebraic operations on weights. This class encompasses all known related practical methods. Additionally, our method works for any physical realization of wavelength conversion, independently whether it is done via optoelectronic conversion or in a fully optical way.