Energy Ecient Trac-Aware Design of On-O Multi-Layer Translucent Optical Networks

Efficiency in energy consumption is attracting greater and greater attention in recent years to the point that it is becoming one of the major constraint steering the evolution of our society. In addition to develop new low-consumption devices, power consumption of optical networks can be further reduced by allowing IP and WDM layer units (racks, shelves, line cards, transponders (TXPs), regenerators) to be jointly switched on/off "following" the daily variation of traffic demand. In order to evaluate the benefits of such on/off strategy, in this study we first propose an accurate model of power consumption and housing constraints of both IP and WDM layers of an IP-over-WDM translucent optical network architecture. Second, we present a Traffic-Aware design technique (i.e., network design allowing reconfiguration when traffic varies) as a Mixed Integer Linear Programming (MILP) formulation based on an extended version of the so-called "connectivity graph". Third, we evaluate the impact on power consumption of multi-layer network architecture when coherent and noncoherent transmission technologies are employed. Fourth, we analyze the energy savings arising from switching on/off devices jointly at IP and WDM layers when traffic demand changes. We show that the contribution of the WDM layer to the power consumption is about the 10% regardless the employed transmission technology and the type of traffic. We demonstrate that in multi-layer networks and for current traffic needs, coherent transmissions do not exploit their extended reach and they show the worst performance in terms of energy consumption although they represent a future-proof technique to cope with the expected increase of traffic.