Opportunistic power savings with coordinated control in data center networks

In this paper, we propose a holistic power management of the data center network (DCN) via coordination among distinct controllers with different functionality and scope. This includes-a local controller (LC) that has visibility only at individual switch/router level, a global controller (GC) that has a global view of the network, and a hint based topology aware user request assignment controller (RAC) that controls placement of the external requests on the endpoint hosts. The key function of these controllers from energy management perspective is to properly direct and consolidate network traffic to maximize low power (or "sleep") opportunities for the network interfaces.We show that the coordinated "hints" provided by the GC are vital to correct the myopic view of LCs and RAC for both avoiding congestion and maximizing network sleep opportunities. We show that these mechanisms can reduce power consumption by upto ∼45% in the common fat-Tree based DCNs using the low power idle (LPI) feature of the Ethernet.