How Poisson is TCP traffic at short time-scales in a small buffer core network?

Abstract

There is widespread debate regarding the nature of TCP traffic in today's Internet - while some researchers have shown that it exhibits long-range dependent (LRD) properties, others argue that it can be modelled as a Poisson process due to the high degree of traffic aggregation that exists in the core. In this paper, we investigate the nature of TCP traffic as the Internet core moves towards an all-optical packet switched network with very limited buffering (few tens of KiloBytes) capability. In particular, we show that the bottleneck link buffers have a large influence on the aggregate TCP arrival process: large buffers can induce synchronisation amongst TCP flows, thus creating significant burstiness (equivalently LRD), but as buffers become smaller, the TCP aggregate can be well approximated as a Poisson process. Our work has major impact on the design and analysis of future high-speed optical packet switched networks with very small buffers.