Implementation and Evaluation of Data Center Congestion Controller with Switch Assistance

In this work, we provide the design and implementation of a switch-assisted congestion control algorithm for data center networks (DCNs). In particular, we provide a prototype of the switch-driven congestion control algorithm and deploy it in a real data center. The prototype is based on few simple modifications to the switch software. The modifications imposed by the algorithm on the switch are to enable the switch to modify the TCP receive-window field in the packet headers. By doing so, the algorithm can enforce a pre-calculated (or target rate) to limit the sending rate at the sources. Therefore, the algorithm requires no modifications to the TCP source or receiver code which considered out of the DCN operators' control (e.g., in the public cloud where the VM is maintained by the tenant). This paper describes in detail two implementations, one as a Linux kernel module and the second as an added feature to the well-known software switch, Open vSwitch. Then we present evaluation results based on experiments of the deployment of both designs in a small testbed to demonstrate the effectiveness of the proposed technique in achieving high throughput, good fairness, and short flow completion times for delay-sensitive flows.