PODCA: A passive optical data center architecture

Abstract

Optical interconnects for data centers can offer reduced power consumption, low latency, and high scalability, compared to electrical interconnects. However, active optical components such as tunable wavelength converters and Micro-Electro-Mechanical Systems (MEMS) switches suffer from high cost or slow reconfiguration times. In this paper, we propose three different Passive Optical Data Center Architectures (PODCAs), depending on the size of the network. Our key device is the Arrayed Waveguide Grating Router (AWGR), a passive device that can achieve contention resolution in the wavelength domain [1]. In our architectures, optical signals are transmitted from fast tunable transmitters and pass through couplers, AWGR, demultiplexers, and are received by wide-band receivers. Our architecture can easily accommodate over 2 million servers. Simulation results show that packet latency is below 9μs, and 100% throughput is achievable. We compare the power consumption and capital expenditure (CapEx) cost of PODCA with other recent optical data center network architectures such as DOS, Proteus, and Petabit. Results show that our architectures can save up to 90% on power consumption and 88% on CapEx.