Asynchronous Optical Traffic Offloading of Hybrid Optical/Electrical Data Center Networks

Abstract

In recent years, hybrid optical/electrical data center network has been considered a promising interconnection technology for large-scale data centers, since it can efficiently provide sufficient bandwidth. A key issue in hybrid optical/electrical data center networks is finding a way to offload burst traffic through optical circuit switches (OCSs), such that the burst traffic can be offloaded timely while the system operation overhead is low. This article extends the idea of Mahout to propose a local-push asynchronous optical traffic offloading strategy, in which each ToR switch offloads the traffic via the OCSs if its queue length is larger than a preset threshold, and transfers the traffic back to electrical packet switches (EPSs) when the backlog is empty. To seek a proper threshold, we develop a fluid-flow model to analyze the performance of the proposed traffic offloading strategy, from which we demonstrate that there is a trade-off between the mean delay of the traffic and the system operation overhead in a typical data center network. Based on such a trade-off, we provide a rule to select the buffer threshold. We show via simulation that the proposed optical traffic offloading strategy with the threshold selection rule outperforms C-through.