Bringing Optical Circuit Switching to the Datacenter

Abstract: Today’s cloud and machine learning workloads are placing ever-increasing demands on datacenter operators in terms of scale and link rates. Optical circuit switches have long been known to be more cost-effective than conventional electrical packet switches at the highest of link rates, but their slow reconfiguration and limited port count have traditionally frustrated operators’ attempts to leverage them in datacenter environments. In recent years several major datacenter operators have made limited use of optical switches in the backbone of their network fabrics, where they can effectively serve large traffic aggregates with only infrequent reconfigurations driven by a centralized controller that monitors network-wide demand.

In this talk, we describe our decade-long journey to design, build and field a demand-oblivious optically-switched network based on a so-called “rotor” switch. RotorNet rapidly reconfigures its constituent rotor switches, decoupling switch configuration from traffic patterns, obviating the need for demand collection and admitting a fully decentralized control plane. At the physical layer, RotorNet relaxes the requirements on the underlying circuit switches—in particular by not requiring individual switches to implement a full crossbar—enabling them to scale to 1000s of ports at a fraction of the cost a comparable electrical packet switch. We will discuss the design, manufacture, deployment, and end-to-end operation of a 128-port optical rotor switch along with supporting NIC hardware and host software at UCSD.

Bio: https://cseweb.ucsd.edu/~snoeren/bio.html