Networking plays an important role in high-performance computing. Most large-scale systems are designed with the network as a central component. However, the energy consumption of interconnection networks has received little attention so far and high-performance computing interconnects lack power-saving features. We describe software and hardware approaches to reducing power consumption by using the network more efficiently or reduce power consumption of unneeded resources by throttling bandwidths. We assess the power consumption of several applications on a small-scale system with different interconnection technologies. We also discuss the importance and basic trade-offs of network topologies with regards to power consumption. We point...