Performance of high-speed TCP applications in networks with very small buffers

In the on-going debate on how large Internet router buffers should be, of particular interest is a recent claim that 10-50 packets of buffering suffice, permitting all-optical buffering in the Internet core. It is argued that TCP traffic, when well-paced (typically by slow access links), can achieve acceptable link utilisation with very small buffers. In this paper we investigate if this result holds in the presence of high-performance scientific applications connecting over high-speed access links. Our results show that the presence of a significant proportion of high-speed access links necessitates larger buffers at the core link. However, we show that end-host TCP pacing by such applications can alleviate the problem effectively.