Abstract

This paper concerns the modelling of Internet packet traffic. In previous work we showed that a Bartlett–Lewis point process, as a model of packet arrivals on backbone links, enjoys strong physical backing and can predict key features. It is based on the surprising empirical observation that flows can often be considered independent for the purpose of modelling packet arrival times. We extend this work in two ways by using a unique dataset obtained from an experiment where all the packets crossing a backbone router are captured. First, this enables an examination of the validity of the fundamental assumptions underlying the model across several links, covering a large range of bandwidths and utilization levels. Second, we extend the model from links to a network node, by examining the merging and splitting properties of the (sub)streams through the router, and mapping these to the merging and splitting properties of the model. We show how the model can, in most cases, capture the observed multiplexing and demultiplexing behaviour of the router, opening up the possibility of its use for understanding traffic flows in networks. We show that failures in the model cannot be accounted for simply through considering utilisation levels, and explain how they can in fact be used as a detector of upstream bottlenecks and traffic shaping.

Keywords: Traffic modelling; Empirical validation; Router measurements; Splitting and merging; Semi-experiments; Cluster processes

Article Outline

1. Introduction

2. The data and data processing

2.1. Full router monitoring

2.2. Data processing

2.2.1. Packet matching

2.2.2. Flow decomposition

2.2.3. Wavelet analysis

3. Semi-experiments and the cluster model

3.1. The semi-experimental method

3.2. A cluster model of packet arrivals

3.3. Splitting and merging of a model

4. Results

4.1. Individual links

4.2. The substreams: splitting and merging

5. Conclusions

Acknowledgements

References

Vitae

The packet matching software was designed and written by K. Papagiannaki, G. Iannacone and T. Ye.