In the last years, the power consumption of telecommunication networks has attracted the attention of both researchers and field experts in order to contain the associated energy bills and reduce their ecological impact. Many of the proposed solutions have been focused exclusively on the reduction of the power consumption, without adequately considering more traditional network engineering objectives such as balancing resource utilization, routing policy, or resilience schemes. As a consequence, network control plane strategies passed from one extreme to the other, from being totally energy-unaware to exclusively energy-efficient at the expenses of load-balancing, with obvious impacts on the power consumption in the former case and on the blocking rate in the latter one. In this paper, we present a hybrid routing and wavelength assignment algorithm that, when the network is lightly loaded, operates in an energy-efficient way, by routing the connections on the paths requiring the lowest amount of energy, while, when the network load increases, it dynamically switches to a pure load-balancing scheme in order to best allocate the available communication resources. The switching decision among load-balancing and energy-awareness is taken dynamically, driven by a threshold on the number of new connections requests reaching the network during a prefixed time window. Simulation results show the effectiveness of the hybrid algorithm, which achieves lower energy consumption than a pure load-balancing algorithm while keeping the network load fairly distributed on the available resources.

Peer Reviewed