Flat Datacenter Networks at Scale (opens in new tab)

The research roots of finding “optimal routing” networks trace back to the late 1970s. Mathematicians defined special kinds of networks called “expanders“. These are graphs with strong connectivity properties guaranteeing no subset of vertices can be isolated from the rest. In 1976, Leslie Valiant gave one of the earliest discussions of such graphs. Following work on Alon-Boppana on trying to understand the best “possible” expanders, mathematicians (notably, Lubotzky, Phillips, and Sarnak) ga...