Augmenting data center networks with a fast reconfigurable optical multistage interconnect

The high bandwidth and power efficiency of optical circuit switching (OCS) have motivated the recent development of hybrid packet/circuit switched (Hypac) data center networks (DCNs). However, current Hypac DCNs use a large MEMS optical switch for OCS communication, which offers limited scalability and expandability. In addition, the slow switching speed of MEMS switches imposes considerable network reconfiguration overhead, which results in degraded network performance. In this paper, we first analyze the fundamental challenges in current MEMS-based Hypac DCNs, and show that fast optical network reconfiguration is the key to effectively utilize OCS in data center communication. We then present a Fast Reconfigurable Baseline Optical Network (FARBON), which, by leveraging the ultra-fast optical switching modules and unique topological properties of the baseline multistage network, allows for rapid network configuration. We also design the control plane and a practical low-jitter traffic scheduling algorithm for FARBON. We demonstrate that FARBON has many desirable features, such as good scalability, low traffic jitter, predictable network performance and tolerance to inaccurate traffic information. The performance of FARBON is evaluated via extensive simulations, and the results show that FARBON significantly outperforms MEMS optical switches in terms of average packet delay and jitter, as well as dealing with correlated traffic, thus is a promising candidate for exploiting the potential of OCS in Hypac DCNs.