This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE/ACM TRANSACTIONS ON NETWORKING 1 Safe and Practical Energy-Efficient Detour Routing in IP Networks

Abstract—The Internet is generally not energy-efficient since all network devices are running all the time and only a small fraction of consumed power is actually related to traffic forwarding. Existing studies try to detour around links and nodes during traffic forwarding to save powers for energy-efficient routing. However, energy-efficient routing in traditional IP networks is not well addressed. The most challenges within an energy-efficient routing scheme in IP networks lie in safety and practicality. The scheme should ensure routing stability and loop- and conges-tion-free packet forwarding, while not requiring modifications in the traditional IP forwarding diagram and shortest-path routing protocols. In this paper, we propose a novel energy-efficient routing approach called safe and practical energy-efficient detour routing (SPEED) for power savings in IP networks. We provide theoretical insight into energy-efficient routing and prove that determining if energy-efficient routing exists is NP-complete. We develop a heuristic in SPEED to maximize pruned links in com-puting energy-efficient routings. Extensive experimental results show that SPEED significantly saves power consumptions without incurring network congestions using real network topologies and traffic matrices. Index Terms—Energy efficiency, intrarouting routing, routing. I