<title>Dimensioning and design of the WDM optical layer in transport networks</title>

Abstract

Wavelength-division-multiplexing (WDM) techniques are now widely spread for high bit rate transmission. Beside the increase of the transmission capacity, WDM should be used in flexible, transparent and cost effective solution for routing large amount of traffic in the optical domain. WDM networking implies a novel network analysis in order to define the traffic transported and routed optically, the protection/restoration schemes more adapted to the optical domain and the reconfiguration possibilities. The WDM optical layer dimensioning is presented here and shows the design and optimization of this transport layer in terms of transmission resources (wavelengths, fibers, amplifiers) and optical node functionalities (optical add-drop multiplexers, optical cross- connect, wavelength translation, . . .). A dimensioning methodology is established, defining the main inputs of this task and the main issues. In this paper different options and issues of the WDM dimensioning are presented and discussed. First, the optical path routing is studied and different routing strategies are given for the minimization of specific parameters. The second issue concerns pure resource allocation. Two different approaches based respectively on wavelength routing and wavelength translation are introduced. The benefits of wavelength translation is discussed and different criteria for the location of this functionality are established. The discussion and analysis are illustrated on several test cases covering different network topology assumptions.