Energy management in IP traffic engineering with Shortest Path routing

Internet energy consumption is rapidly becoming an issue due to the exponential traffic growth and the rapid expansion of communication infrastructures worldwide. In this paper we propose an off-line IP traffic engineering approach that allows to adapt the network energy consumption to different daily traffic scenarios (e.g., night, morning), by switching off and on (putting in sleeping mode and waking up) communication interfaces (links) and entire routers. We focus on routing domains where OSPF (Open Shortest Path First) protocol is adopted and we aim at optimizing energy consumption and network congestion by efficiently configuring the OSPF link weights. We present two heuristics, the Greedy Algorithm for Energy Saving (GA-ES) and the Two-stage Algorithm for Energy Saving (TA-ES). The computational results for three real network topologies show that it is possible to switch off up to 80% of the core nodes during low traffic periods (night hours), while moderately increasing the network congestion.