We study
the effect of the IP router buffer size on the throughput of HighSpeed
TCP (HSTCP). We are motivated by the fact that in high speed routers,
the buffer size is important as such a large buffer size might be a
constraint. We first derive an analytical model for HighSpeed TCP and
we show that for small buffer size equal to 10% of the bandwidth-delay
product, HighSpeed TCP can achieve more than 90% of the
bottleneck capacity. We also show that setting the buffer size equal to
20% can increase the utilization of HighSpeed TCP up to 98%. On the
contrary, setting the buffer size to less than 10% of the
bandwidth-delay product can decrease HighSpeed TCP's throughput
significantly. We also study the performance effects under both
DropTail and RED AQM. Analytical results obtained using a fixed-point
approach are compared to those obtained by simulation.
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