Thor: a server-level hybrid switching data center network with heterogeneous topologies

Abstract

Optical interconnects are promising to address the dilemma faced by traditional electrical networks in data centers. However, some issues, including weak connectivity of the topology, limited scalability of the control system, and inefficient use of WDM technologies, limit the deployment potential of optical networks. To address these issues, we propose a novel hybrid network called Thor. By employing different topologies for the optical and electrical networks, Thor achieves server-level optical interconnects and can better exploit the unique properties of circuit switching and packet switching. To build a more scalable and responsive control plane, Thor uses a distributed control system built atop the electrical network. Moreover, we develop a new optical switch to more efficiently utilize multiple wavelengths. Our evaluation results show that Thor is able to deliver ∼ 90% bisection bandwidth of a non-blocking electrical network under realistic traffic patterns. Moreover, by transmitting mice and elephant flows separately in each of the two networks, Thor is able to provide an order of magnitude speedup in average flow completion times for mice flows compared to conventional approaches.