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On the 95-Percentile Billing Method

  • Xenofontas Dimitropoulos
  • Paul Hurley
  • Andreas Kind
  • Marc Ph. Stoecklin
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5448)

Abstract

The 95-percentile method is used widely for billing ISPs and websites. In this work, we characterize important aspects of the 95-percentile method using a large set of traffic traces. We first study how the 95-percentile depends on the aggregation window size. We observe that the computed value often follows a noisy decreasing trend along a convex curve as the window size increases. We provide theoretical justification for this dependence using the self-similar model for Internet traffic and discuss observed more complex dependencies in which the 95-percentile increases with the window size. Secondly, we quantify how variations on the window size affect the computed 95-percentile. In our experiments, we find that reasonable differences in the window size can account for an increase between 4.1% and 42.5% in the monthly bill of medium and low-volume sites. In contrast, for sites with average traffic rates above 10Mbps the fluctuation of the 95-percentile is bellow 2.9%. Next, we focus on the use of flow data in hosting environments for billing individual sites. We describe the byte-shifting effect introduced by flow aggregation and quantify how it can affect the computed 95-percentile. We find that in our traces it can both decrease and increase the computed 95-percentile with the largest change being a decrease of 9.3%.

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References

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    The Tcpdump team: tcpdump, http://www.tcpdump.org/
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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Xenofontas Dimitropoulos
    • 1
  • Paul Hurley
    • 2
  • Andreas Kind
    • 2
  • Marc Ph. Stoecklin
    • 2
  1. 1.ETH ZürichSwitzerland
  2. 2.IBM Research ZürichSwitzerland

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