High throughput data center topology design
Ankit Singla, P. Brighten Godfrey, Alexandra Kolla · 2014
With high throughput networks acquiring a crucial role in supporting data-intensive applications, a variety of data center network topologies have been proposed to achieve high capacity at low cost. While this work explores a large number of design points, even in the limited case of a network of identical switches, no proposal has been able to claim any notion of optimality. The case of het-erogeneous networks, incorporating multiple line-speeds and port-counts as data centers grow over time, intro-duces even greater complexity. In this paper, we present the first non-trivial upper-bound on network throughput under uniform traffic pat-terns for any topology with identical switches. We then show that random graphs achieve throughput surpris-ingly close to this bound, within a few percent at the scale of a few thousand servers. Apart from demonstrating that homogeneous topology design may be reaching its lim-its, this result also motivates our use of random graphs as building blocks for design of heterogeneous networks. Given a heterogeneous pool of network switches, we ex-plore through experiments and analysis, how the distri-bution of servers across switches and the interconnec-tion of switches affect network throughput. We apply these insights to a real-world heterogeneous data center topology, VL2, demonstrating as much as 43 % higher throughput with the same equipment. 1