Performance-Aware Energy Saving for Data Center Networks

Today's data center networks (DCNs) tend to have tens to hundreds of thousands of servers that provide massive and sophisticated services. The architectural design of DCNs are usually over-provisioned for peak workloads and fault tolerance. Statistically, DCNs remain highly under-utilized, with typical utilization of around 30%. Network over-provisioning and under-utilization can be exploited for energy-saving. Most research efforts on DCN energy saving focus on how to save maximum energy but have little or no consideration to the performance of the residual network. Thus, the DCN performance can become degraded and the network left vulnerable to sudden traffic surges. In this paper, we have studied the energy-saving problem in DCNs while preserving network performance. The problem was formulated as mixed integer linear problem (MILP) solvable by CPLEX in order to minimize the energy consumed by DCN; meanwhile, safety threshold constraints for links utilization are met. To overcome CPLEX high computational time, a heuristic algorithm to provide practical and efficient solution for the MILP is introduced. The heuristic algorithm uses switches grouping and links consolidation to switch the traffic to a small number of network devices and turn off unused switches and links. Valiant load balancing is used to distribute the loads over active links. Simulation experiments using synthetic and real packet traces were conducted to validate the heuristic in terms of energy consumption and network performance. The results show that the heuristic can save up to 45% of the network energy and improve the average imbalance scores for links and switches by more than 50% with minimal effect on network performance.