“…The former achieves power saving by deploying appropriate policies (e.g., Dynamic Voltage and Frequency Scaling (DVFS) in [13], Low Power Idle (LPI) in [14]) to control and adjust the working status of components in nodes or links and make their power consumption adapt to the transmitted traffic on them [15]. The latter achieves power saving from a global view of networks by improving the existing routing protocols, routing algorithms or network architectures (e.g., an enhanced version of OSPF for energy saving in [16], a power-efficient QoS routing scheme in [17], an energy-aware IP traffic engineering in [18]), or even innovating them thoroughly (e.g., a completely new design of green reconfigurable router [19]). In this paper, we consider the network-level power saving from a green routing point of view, which can relieve the energy and environment issues in the future network communication.…”