Flyover: A Cost-Efficient and Scale-Out Data Center Network Architecture

Torus, which is simple and incrementally expandable, could perfectly fit the scale-out model of current large scale computing systems, such as data centers. However, on the downside, torus suffers from its long network diameter. One way to address this problem is using random shortcuts. However, this approach does not consider the variety of data center traffic, and leads to severe non-uniform network performance. To address this problem, we propose the Flyover, which exploits the flexibility of optical circuit switching to add on-demand shortcuts, as a cost-efficient and scale-out network architecture for DCNs. The following three features guarantee Flyover a good performance. First, a new defined serpent flow instead of the elephant flow is prioritized. Unlike the elephant flow, which is big in size, the serpent flow is big in both size and distance. Through this, the electrical torus network could be maximally relieved and the overall network performance is optimized. Second, Flyover generates region-to-region instead of the point-to-point shortcuts. Therefore, the valuable optical shortcuts could be fully utilized. Third, a semi-random heuristic algorithm is proposed to achieve the advantages of both reducing computation time and improving network performance. Furthermore, several ways to expand Flyover are discussed and evaluated to make sure that Flyover is highly scalable. Finally, Flyover is extensively analyzed and compared with its counterparts using both simulations and prototypes. The results show that Flyover could maximally improve the network throughput by 135% and latency by 277%.