Leveraging Commodity Photonics to Reduce Datacenter Network Latency

[摘要] Most datacenter network (DCN) designs focus on maximizing bisection bandwidthrather than minimizing server-to-server latency. They are, therefore, ill-suitedfor important latency-sensitive applications, such as high performancecomputing, realtime analytic systems and high-frequency financial trading.Although there are a number of existing approaches to reduce network latency,they are only partially effective, workload dependent, and often requirenetwork protocol changes.In this thesis, we explore architectural approaches to building a low-latencyDCN and introduce Quartz, a new optical design element consisting of a fullmesh of switches connected by an optical ring. We can reduce the networklatency of a hierarchical or random network by replacing portions of it with aQuartz ring.Our analysis shows that, in a standard 3-tier DCN, replacing highport-count core switches with Quartz can significantly reduce switching delays,and replacing groups of top-of-rack and aggregation switches with Quartz cansignificantly reduce congestion-related delays from cross-traffic.We overcomethe complexity of wiring a complete mesh by using low-cost optical multiplexersthat enable us to efficiently implement a logical mesh as a physical ring.Weevaluate our performance using both simulations and a small working prototype.Our evaluation results confirm our analysis, and demonstrate that it ispossible to build low-latency DCNs using inexpensive commodity elements withoutsignificant concessions to cost, scalability, or wiring complexity.

[发布机构] University of Waterloo

[关键词] Computer Science