Baatdaat: Measurement-based flow scheduling for cloud data centers

Software-Defined Networking (SDN) allows for efficient network-wide Traffic Engineering through the logical centralization of the control plane over individual switches that perform packet forwarding independently. Such abstraction is particularly suitable for Data Center (DC) networks that need to react to fluctuating traffic dynamics over short timescales. In this paper, we propose a low-cost, SDN-based system that exposes the temporal network-wide utilization through direct measurement, rather than estimation. We then present the Baatdaat¹ flow scheduling algorithm which uses spare DC network capacity to mitigate the performance degradation of heavily utilized links. Results show that Baatdaat achieves close to optimal Traffic Engineering by reducing network-wide maximum link utilization by up to 18% over ECMP, while at the same time improving flow completion time by as much as 41% - 95% for different types of flows.