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