Controlling the Delay of Small Flows in Datacenters

As data centers grow in size, the communication between servers has emerged as a major bottleneck. Studies have shown that data center workloads are highly variable in sizes, comprising of a mix of mice and elephant flows which, when coupled with hard to predict arrivals, make bandwidth provisioning and flow scheduling a challenging task. There has been a significant progress in excess bandwidth provisioning and flow scheduling algorithms, especially using hybrid electrical-optical networks, aimed at providing effective throughput to elephant flows while ignoring the delay of small flows. The latency of small flows, however, is an important performance metric and existing solutions for improving this metric for traditional packet switched as well as hybrid data center networks continue to be inadequate. We aim at looking at the design of a data center network which ensures adequate bandwidth provisioning and minimizes delay for mice flows effectively. In this paper, we propose a novel hybrid architecture along with simple flow routing schemes to achieve these goals. The design schemes proposed in this paper can be incorporated in the existing data center networks. We evaluate the performance of our scheme and compare it to other existing schemes through simulations.