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By Manish Jain and Constantinos Dovrolis 2003. End-to-End Available Bandwidth: Measurement Methodology, Dynamics, and Relation With TCP Throughput. Presented by Caroline Williams. Purpose. - PowerPoint PPT Presentation
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By
Manish Jain and
Constantinos Dovrolis
2003
Presented by Caroline Williams
End-to-End Available Bandwidth 1Rosa Williams
PurposeThe 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
End-to-End Available Bandwidth 2Rosa Williams
MotivationAvailable 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.
End-to-End Available Bandwidth 3Rosa Williams
DefinitionEnd-to-end Avail-bw
SND H H H RCV
C: End-to-end capacity
Ci: transmission rate in bits per second of link i
Path:
mini=1
HCi
i
: average utilization of link i during (t0, t0 + )(t0)
Ai(t0) Ci[1 -
i(t0) ]: avail-bw of link i
A(t0): end-to-end avail-bw minH
i=1
{Ci [1 - i(t0)] }
End-to-End Available Bandwidth 4Rosa Williams
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 > 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.”
End-to-End Available Bandwidth 5Rosa Williams
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
End-to-End Available Bandwidth 6Rosa Williams
Verification (NS Simulation)
End-to-End Available Bandwidth 7Rosa Williams
Verification (Experimental)
End-to-End Available Bandwidth 8Rosa Williams
Dynamics: Variability and Load Conditions
End-to-End Available Bandwidth 9Rosa Williams
DynamicsVariability and Statistical Multiplexing
End-to-End Available Bandwidth 10Rosa Williams
Dynamics: Effect of the Stream Length
End-to-End Available Bandwidth 11Rosa Williams
DynamicsEffect of the Fleet Length
End-to-End Available Bandwidth 12Rosa Williams
TCP and Avail-BW
End-to-End Available Bandwidth 13Rosa Williams
IntrusivenessPathload
End-to-End Available Bandwidth 14Rosa Williams
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”.
End-to-End Available Bandwidth 15Rosa Williams
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.
End-to-End Available Bandwidth 16Rosa Williams