Migration to energy efficient routers: Where to start?

Given the assumption that network equipment vendors will soon deploy new energy saving mechanisms in their routers, the question we are aiming to answer is this: Where in the network to start the migration to energy efficient routers, and how large is the impact of the migration scheduling on the total energy saving? To this end, the paper studies a scenario where network nodes can reduce the power consumption proportional to the router traffic load, and elaborates on the impact of the migration node sequence that determines at which point in time which node migrates. While every router can gradually increase and decrease the consumption based on load, at the same time, the network as a whole is subject to a gradual migration on its own, where energy efficient network routers are installed over multiple planning periods. Our results show that an increase of saved energy up to 12 percentage points is possible only by changing the migration sequence of energy efficient routers. Additionally, we show that deploying mechanisms of Traffic Engineering can further significantly improve the overall energy savings especially during the early stages of migration.