End-to-End Available Bandwidth: Measurement Methodology, Dynamics, and Relation With TCP Throughput

1
End-to-End Available Bandwidth Measurement
Methodology, Dynamics, and Relation With TCP
Throughput

• By
• Manish Jain and
• Constantinos Dovrolis
• 2003

Presented by Caroline Williams
2
Purpose

• The authors are not satisfied with the current
  definition of available bandwidth nor the tools
  to measure available bandwidth.
• The authors propose
• A concise available bandwidth definition
• A methodology to measure available bandwidth
• A tool that implements the methodology

3
Motivation

• Available bandwidth is an important metric for
• Congestion control
• Streaming applications
• Quality-of-service verification
• Server selection
• Overlay networks
• As such, the definition should be agreed upon,
  the measurements accurate and nonintrusive.

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DefinitionEnd-to-end Avail-bw
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MethodologySelf-Loading Periodic Streams (SLoPS)

• A stream consists of K packets of size L, sent at
  constant rate R
• One-way delays (OWD) of successive packets at RCV
  show an increasing trend when R gt A
• A is converged upon through an iterative
  algorithm at RCV. RCV notifies SND of new R.
  The algorithm will converge to a range Rmin,
  Rmax that includes A.

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ImplementationPathload

• Process SND generates fleets of timestamped
  packet streams for R
• Process RCV determines the OWD trend for the
  fleet. Then, adjusts Rmin or Rmax according to
  the SLoPS algorithm. A new R (halfway between
  Rmin and Rmax) is fed back to SND.
• Continue the above two steps until Rmax Rmin
  a user defined resolution
• Rmin, Rmax can be calculated in less than 15
  seconds using default parameters

7
Verification (NS Simulation)
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Verification (Experimental)
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Dynamics Variability and Load Conditions
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DynamicsVariability and Statistical Multiplexing
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Dynamics Effect of the Stream Length
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DynamicsEffect of the Fleet Length
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TCP and Avail-BW
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IntrusivenessPathload
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Conclusion

• Available bandwidth is elusive
• Jain and Dovrolis have provided a methodology
  that reports a range of rates that includes
  avail-bw
• Their tool is nonintrusive and reliable in a
  wide range of load conditions and path
  configurations.

16
References

• Information Sciences Institute. ns-2.
  http//nsnam.isi.edu/nsnam/index.php/Main_Page.
  October 21, 2007.
• M. Jain, C. Dovrolis. End-to-end available
  bandwidth measurement methodology, dynamics, and
  relation with TCP throughput. IEEE/ACM Trans.
  Netw. 11(4) 537-549 (2003)
• T. Oetiker. MRTG - The Multi Router Traffic
  Grapher. http//oss.oetiker.ch/mrtg/. October
  21, 2007.