1 Trading Power Savings for Blocking Probability in Dynamically Provisioned WDM Networks

In those networking scenarios (e.g., the stationary/mobile wireless paradigm) where limited energy storage capabilities is a limiting factor, power efficiency has been studied extensively for a long time. In the last few years, the steadily growing power consumption figures of ICT [1][2] along with a recent public awareness of the possible environmental effects, broadened the focus of the research efforts towards more power conscious solutions also for wired networks. One promising solution going in this direction is represented by transparent wavelength division multiplexing (WDM) networks, where all-optical circuits (or lightpaths) carry the network traffic from the source to the destination node in the optical domain, i.e. without any optical-to-electrical (O-E-O) conversion. To further improve network power efficiency, several approaches have been proposed in the literature attempting to reduce the power consumption in transparent WDM networks [3][4]. Among them, power aware (PA) routing and wavelength assignment (RWA) algorithms are receiving a lot of attention. One possible solution for the PA-RWA problem is to limit the number of devices in the network that need to be powered-on to support the lightpath requests [5]. These methods, however, have an adverse impact on the length of the provisioned lightpaths. In order to efficiently use as much powered-on network resources as possible, the path length is, on average, longer than the one found with traditional (and less power efficient) shortest pat