Network Performance under Physical Constraints

The performance of an interconnection network in a massively parallel architecture is subject to physical constraints whose impact needs to be re-evaluated from time to time. Fat-trees and low dimensional cubes have raised a great interest in the scientiic community in the last few years and are emerging standards in the design of interconnection networks for massively parallel computers. In this paper we compare the communication performance of these two classes of interconnection networks using a detailed simulation model. The comparison is made using a set of synthetic benchmarks, taking into account physical constraints, as pin and bandwidth limitations, and the router complexity. In our experiments we consider two networks with 256 nodes, a 16-ary 2-cube and 4-ary 4-tree.