On the energy consumption of IP-over-WDM architectures

Today's “green thrust” has been completely steering the evolution of our society. Therefore, since enhancements on telecommunication networks are expected to cope with the growth of traffic demand, energy consumption is becoming a crucial design metric. In this paper we focus on IP over Wavelength Division Multiplexing (IPoWDM) optical network architectures, where optical circuits (or lightpaths) interconnect IP routers. Various implementations of IPoWDM networks are possible, e.g., transparent, translucent or opaque each accounting different routing and switching constraints, in order to evolve from the classic IPoWDM approach, where only signal transmission is performed optically. Although it is a common belief that “more optical” architectures can generally guarantee a much lower total power consumption, we show that identifying the most energy-efficient IPoWDM architecture is not a trivial task. In fact we demonstrate that the most energy-efficient architecture depends on some network parameters such as number of nodes, link length and average distance between nodes. This work provide an analytical framework by which we draw guidelines to (a) assess under which conditions optical switching actually becomes more desirable than electronic switching and (b) evaluate which architecture, among those employing optical switching, is more energy-efficient under different parameter settings.