High-port and low-latency optical switches for disaggregated data centers: the Hipoλaos switch architecture

The emergence of disaggregation in data center (DC) architectures as a way to increase resource utilization introduces significant challenges to the DC switching infrastructure, which has to ensure high bandwidth and low-latency communication along with high-radix connectivity. This paper examines the network requirements in disaggregated systems and reviews the credentials of state-of-the-art high-radix optical switch architectures. We also demonstrate a novel optical packet switch design, called Hipoλaos, that satisfies these requirements by combining N-port broadcast-and-select and N × N arrayed waveguide grating router-based forwarding schemes in N2-port connectivity configurations. The Hipoλaos switch provides sub-μs latency and high throughput performance by utilizing distributed control and optical feed-forward buffering in a modified Spanke architecture. Feasibility of a 256 port Hipoλaos layout with a four-packet buffering stage is experimentally demonstrated at 10 Gb/s, revealing error-free performance with a mean power penalty value of 2.19 dB. Simulation analysis is carried out for a 256 node system and eight traffic profiles; this analysis reveals a low latency value of only 605 ns, with throughput reaching 85% even when employing only two-packet buffers. Finally, the architecture’s scalability up to 1024 × 1024 designs is discussed, along with a power consumption analysis and a roadmap toward an integrated version of the switch.