In this article we introduce and evaluate a method for optimizing the route
r arbitration policy in point-to-point networks. These networks use multipl
e high-speed, low-cost routers to rapidly switch data directly between data
sources and destinations. We assume that routers use an arbitration algori
thm that has the ability to assign different priorities to different links
thus controlling the distribution of available bandwidth among channels. We
propose an analytical method that allows us to determine the correct prior
ities for channels so as to achieve fair arbitration thus minimizing latenc
y, increasing throughput and eliminating tree saturation.
In our study we used data generated by a simulation tool to validate the pr
oposed analytical model for determining the weights (priorities) of router
ports and to evaluate the resulting performance improvements. Link usage st
atistics were recorded by the simulator for the purpose of performing a det
ailed investigation on congestion effects particularly tree saturation.
The method was applied to the ServerNet(TM) System Area Network (SAN), deve
loped by Tandem Computers Inc. (C) 1999 Elsevier Science B.V. All rights re
served.