CycleDCN: A Scalable Architecture for Optical Data Center Network.

In this paper, we propose a bufferless data center network architecture (CycleDCN). CycleDCN is implemented as three-stage Clos network with arrayed wavelength grating routers (AWGRs) and tunable wavelength converters (TWCs) as the core device. Multi-wavelength routing and multi-stage structure make the routing problem of CycleDCN more complex. Based on the unique topology of CycleDCN, we propose two methods for route scheduling and wavelength assignment. One is based on integer linear programming, and the other is the heuristic algorithm based on the wavelength contention probability of each flow, which is called low contention probability first (LCF). With a centralized controller and either of the above methods, the proposed DCN architecture can achieve high scalability, high throughput, and low latency without using any optical buffer. The simulation results show that our proposed architecture can achieve about 83% throughput and less than 200ns latency at full load while accommodating thousands of ToR connections.