For some reason the above URL doesn't include a link to the paper [1], just the embedded video [2] of Torsten's talk MSR posted a few days ago and a link to the slides; however, this URL includes everything (slides, video, and paper too): https://htor.inf.ethz.ch/publications/index.php?pub=187

[1] Slim Fly: A Cost Effective Low-Diameter Network Topology (2014) [pdf] https://htor.inf.ethz.ch/publications/img/sf_sc_2014.pdf

[2] Network Topologies for Large-scale Datacenters: It's the Diameter, Stupid! (2016) [video] https://www.youtube.com/watch?v=F8F0JN6X0fE