A Scalable, Commodity Data Center Network Architecture

This paper describes fat-tree topology to utilize commodity switch in data center networking.
As the price of high-end switch is too expensive, many people tried to use commodity hardware to reduce cost. Also, this tries to increase bisection bandwidth, which is becoming more important due to MapReduce type applications. But it comes not for free. Especially, this makes load balancing and wiring more complex, in turn this solution impractical.