Graph-Theoretic Algorithms for Energy Saving in IP Networks

Energy saving in the Internet can be achieved by controlling the topology of the network and by turning off, or by putting into sleep mode, network links or devices. Indeed actual Internet topologies have space to turn off some links and devices to reduce the energy consumed in off-peak periods, e.g., during the night. This should be achieved still guaranteeing specific properties of the resulting topology, as the connectivity among terminals or the resulting path lengths, to cite a few. In this chapter we present different methodologies, based on the graph theory, that allow to identify in the network graph links that can be put in sleep mode. In the following we indicate that these links can be switched off. In practice this switching off corresponds to IP line cards of a router that are put into sleep mode. In this way these line cards consume a low amount of energy. We denote the family of the discussed algorithms as Graph-based Energy Saving (GES). Different graph properties can be used and algorithms based on these properties can be defined.