Why is the Internet Traffic Bursty in Short Time Scales?

Authors: Hao Jiang, Constantinos Dovrolis

Complete Citation

Hao Jiang, Constantinos Dovrolis, Why is the Internet Traffic Bursty in Short Time Scales?, ACM SIGMETRICS Performance Evaluation Review, Volume 33, Issue 1, Pages: 241 - 252, June 2005, DOI Bookmark: http://doi.acm.org/10.1145/1071690.1064240

Abstract

Internet traffic exhibits multifaceted burstiness and correlation structure over a wide span of time scales. Previous work analyzed this structure in terms of heavy-tailed session characteristics, as well as TCP timeouts and congestion avoidance, in relatively long time scales. We focus on shorter scales, typically less than 100-1000 milliseconds. Our objective is to identify the actual mechanisms that are responsible for creating bursty traffic in those scales. We show that TCP self-clocking, joint with queueing in the network, can shape the packet interarrivals of a TCP connection in a two-level ON-OFF pattern. This structure creates strong correlations and burstiness in time scales that extend up to the Round- Trip Time (RTT) of the connection. This effect is more important for bulk transfers that have a large bandwidth-delay product relative to their window size. Also, the aggregation of many flows, without rescaling their packet interarrivals, does not converge to a Poisson stream, as one might expect from classical superposition results. Instead, the burstiness in those scales can be signifficantly reduced by TCP pacing. In particular, we focus on the importance of the minimum pacing timer, and show that a 10-millisecond timer would be too coarse for removing short-scale traffic burstiness, while a 1-millisecond timer would be sufficient to make the traffic almost as smooth as a Poisson stream in sub-RTT scales.

Annotations

This paper examines the link between the TCP protocol and the short scale burstiness of Internet traffic. The paper measured burstiness by using energy function and drew the following conclusions:

• TCP self-clocking, joint with queueing in the network, can shape the packet interarrivals of a TCP connection in a two-level ON-OFF pattern.

• The aggregation of many flows does not converge to a Poisson stream. But I am not convinced by the way they compute energy for aggregated traffic.

• TCP pacing is an effective way to reduce the sub-RTT burstiness of Internet traffic.