Sirius: A Flat Datacenter Network with Nanosecond Optical Switching. SIGCOMM 2020 full talk

August 5, 2020
Paolo Costa | Microsoft Research

The increasing gap between the growth of datacenter traffic and electrical switch capacity is expected to worsen due to the slowdown of Moore’s law, motivating the need for a new switching technology for the post-Moore’s law era that can meet the increasingly stringent requirements of hardware-driven cloud workloads. In this talk, I will present Sirius, an optically-switched network for datacenters providing the abstraction of a single, high-radix switch that can connect thousands of nodes—racks or servers—in a datacenter while achieving nanosecond-granularity reconfiguration. At its core, Sirius uses a combination of tunable lasers and simple, passive gratings that route light based on its wavelength. Sirius’ switching technology and topology is tightly co-designed with its routing and scheduling as well as with novel congestion-control and time-synchronization mechanisms to achieve a scalable yet flat network that can offer high bandwidth and very low end-to-end latency. Through a small-scale prototype using a custom tunable laser chip that can tune in less than 912 ps, we demonstrate 3.84 ns end-to-end reconfiguration atop 50-Gbps channels. Through large-scale simulations, we show that Sirius can approximate the performance of an ideal, electrically-switched non-blocking network with up to 74-77% lower power.