Random Folded Clos Topologies for Datacenter Networks

In datacenter networks, big scale, high performance and fault-tolerance, low-cost, and graceful expandability are pursued features. Recently, random regular networks, as the Jellyfish, have been proposed for satisfying these stringent requirements. However, their completely unstructured design entails several drawbacks. As a related alternative, in this paper we propose Random Folded Clos (RFC) networks. They constitute a compromise between total randomness and maintaining some topological structure. As it will be shown, RFCs preserve important properties of Clos networks that provide a straightforward deadlock-free equal-cost multi-path routing and enough randomness to gracefully expanding. These networks are minutely compared, in topological and cost terms, against fat-trees, orthogonal fat-trees and random regular graphs. Also, experiments are carried out to simulate their performance under synthetic traffics that emulate common loads in datacenters. It is shown that RFCs constitute an interesting alternative to currently deployed networks since they appropriately balance all the important design requirements. Moreover, they do that at much lower cost than the fat-tree, their natural competitor. Being able up to connect the same number of compute nodes, saving up to 95% of the cost, and giving similar performance.