Universal Routing and Performance Assurance for Distributed Networks

In this paper, we show that universal routing can be achieved with low overhead in distributed networks. The validity of our results rests on a new network called the fat-stack. We show that from a routing perspective the fat-stack is efficient and is suitable for use as a baseline distributed network and as a crucial benchmark architecture for evaluating the performance of specific distributed networks. We show that the fat-stack is efficient by proving it is universal. A requirement for the fat-stack to be universal is that link capacities double up the levels of the network. We use methods developed in the areas of VLSI and processor interconnect for much of our analysis. We then show how the fat-stack can be an effective benchmark architecture and how to scale the network from a VLSI graph layout to a large-scale distributed topology. Our universality proof shows that a fat-stack of area Θ(A) can simulate any competing network of area A with O(log 3 2 A) overhead independently of wire delay. The universality result implies that the fat-stack of a given size is nearly the best routing network of that size. The fat-stack is also the minimal universal network for an O(log 3 2 A) overhead in terms of number of links. Actual simulations show that the fat-stack outperforms a mesh-based distributed network of comparable hardware usage. Our work helps explain why some deployed networks function in the way they do in terms of routing. It also provides an exemplary network of proven efficiency and scalability for building new distributed systems.