Cutting the electric bill by routing and wavelength assignment with time-zones and time-of-use prices

We consider an energy-aware WDM core network, where the electric prices differ according to time intervals of the day, referred to as time-of-use rates. Since a large backbone network may have nodes scattered over several time zones, we exploit the time-of-use rates to lower the electric bill of the network provider. By using an ILP formulation of the bill minimization problem, we investigate the gain of total electric bill over two approaches where capacity and energy are optimized under different network traffic load conditions.