measuring bandwidth between planetlab nodes
DESCRIPTION
Measuring Bandwidth between PlanetLab Nodes. Sung-Ju Lee, Puneet Sharma, Sujata Banerjee, Sujoy Basu Hewlett-Packard Laboratories, Palo Alto, CA. Rodrigo Fonseca University of California, Berkeley, CA. Published in the proceedings of PAM 2005 – Passive & Active Measurement Workshop. Outline. - PowerPoint PPT PresentationTRANSCRIPT
Presentation Date : 16 Nov 2005 1
Measuring Bandwidth between PlanetLab Nodes
Sung-Ju Lee, Puneet Sharma,
Sujata Banerjee, Sujoy Basu
Hewlett-Packard Laboratories, Palo Alto, CA
Rodrigo Fonseca
University of California, Berkeley, CA
Published in the proceedings of PAM 2005 – Passive & Active Measurement Workshop
Presentation Date : 16 Nov 2005 2
Outline
1. Goals
2. Measurement Experience on PlanetLab
3. Measurement analysis
4. Conclusions
Presentation Date : 16 Nov 2005 3
Goals
To understand the bandwidth characteristic of network paths connecting PlanetLab nodes.
To obtain insights into potential trends that will enable scalable bandwidth estimation.
Presentation Date : 16 Nov 2005 4
Measurement experience on PlanetLab
A. Methodology
They did not develop a new bandwidth estimation tool. Rather, they measure the bandwidth/capacity of the links by different available tools and report their findings.
They collected 2 two sets of data at two different time periods.
• First set – Aug. 11th , 2004 – Sep. 6th , 2004
• Second set – Jan. 5th , 2005 – Jan. 18th , 2005
Presentation Date : 16 Nov 2005 5
Measurement experience on PlanetLab
B. Tools they tried
Per-hop capacity estimation tools
pathchar and pchar – they can’t build them on the current PlanetLab nodes that run a Linux kernel version 2.4.22. pathchar and pchar can only support Linux kernel 2.0.30 and 2.3 respectively.
Clink – program hang, they suspect it’s also the problem of the Linux kernel version.
Presentation Date : 16 Nov 2005 6
Measurement experience on PlanetLab
End-to-end capacity tools
bprobe – works only on SGI Irix. SProbe – it doesn’t report any value as dete
cting cross traffic. pathrate – the only capacity estimation tool
they can successfully run on Planetlab.
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Measurement experience on PlanetLab
End-to-end available bandwidth tools
pathload – they ran into an invalid argument error on connect.
IGI – they get poor accuracy with high variance in the estimation of the same pair on sequential attempts.
Spruce – more accurate results than the above two tools but it requires the knowledge of the capacity of the path.
Presentation Date : 16 Nov 2005 8
Measurement experience on PlanetLab
End-to-end available bandwidth tools
pathChirp – failed to run on the version 3 rollout of PlanetLab (first set of data is obtained by the old version 2 of PlanetLab).
Between the two measurement periods, PlanetLab upgraded their software from version 2 to version 3.
Presentation Date : 16 Nov 2005 9
Measurement Analysis
They use pathrate version 2.4.0 for the first set of data. Some negative values are found, then they reported to the authors of pathrate and use 2.4.1b for the second measurement.
The collected bottleneck capacity data on 12,006 network paths from 279 nodes in the first set data and 21,861 paths from 178 nodes for the second set.
Presentation Date : 16 Nov 2005 10
Measurement Analysis
End-to-end capacity statistics
Set 1 Set 2
No. of nodes 279 178
Measurement period 8/11/04~9/6/04 1/5/05~1/18/05
PlanetLab version Version 2 Version 3
No. of pairs 12,006 21,861
Min. capacity 0.1 Mbps 0.3 Mbps
Max. capacity 1210.1 Mbps 682.9 Mbps
Ave. capacity 63.44 Mbps 64.03 Mbps
Median capacity 24.5 Mbps 91.4 Mbps
Std. deviation 119.22 Mbps 43.78 Mbps
Presentation Date : 16 Nov 2005 11
Measurement Analysis
End-to-end capacity statistics
Capacity (C)Set 1 Set 2
No. of Paths Per(%) No. of Paths Per(%)
C < 20 Mbps 4013 33.42 6733 30.8
20Mbps≦C<50Mbps 4246 35.37 1910 8.74
50Mbps≦C<80Mbps 674 5.61 1303 5.96
80Mbps≦C<120Mbps 2193 18.27 11744 53.72
120Mbps≦C<200Mbps 207 1.72 139 0.64
200Mbps≦C<500Mbps 392 3.27 21 0.096
500Mbps≦C 281 2.34 11 0.05
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Measurement Analysis
Bandwidth capacity for all pairs measured
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Measurement Analysis
Capacity by regions (Mbps)
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Measurement Analysis
They define asymmetry factor between two nodes i and j, αi,j,
),max(,,
,,
, BWBWBWBW
ijji
ijji
ji
where BWi,j is the bottleneck bandwidth from node i to node j
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Measurement Analysis
Asymmetry factor distribution
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Measurement Analysis – Temporal Analysis
Comparison of End-to-end capacity statistics of common node pairs in Sets1 and 2.
Set 1 Set 2
No. of common pairs 3,409
Measurement period 8/11/04~9/6/04 1/5/05~1/18/05
PlanetLab version Version 2 Version 3
Min. capacity 0.1 Mbps 0.5 Mbps
Max. capacity 1014.1 Mbps 152.6 Mbps
Ave. capacity 55.79 Mbps 71.09 Mbps
Median capacity 24.3 Mbps 97.3 Mbps
Std. deviation 109.94 Mbps 39.32 Mbps
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Measurement Analysis – Temporal Analysis
End-to-end capacity distribution of common node pairs in Sets 1 and 2
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Measurement Analysis – Temporal Analysis
Asymmetry factor distribution of common pairs in Sets 1 and 2
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Measurement Analysis – Correlation Study
Motivation: look for the relationship or trend between latency & bandwidth (capacity). The define two metrics for studying the capacity and latency correlation.
BWBW
Lati
BWi
min,
max,
BWBW
nodeclosest
BW
_
max
Relative bandwidth correlation metric
Relative bandwidth correlation penalty metric
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Measurement Analysis – Correlation Study
Bandwidth/delay correlation
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Conclusions
Present the analysis from the two sets of data.
Show the problems of the deployments of the network measurement tools on PlanetLab.
The capacity of paths may have an order of magnitude difference even when they are sourced from the same node and similarly for the same receiver.
Paths between two nodes do net necessarily show capacity symmetry.
Presentation Date : 16 Nov 2005 23
Conclusions
They observed bandwidth limit violations that may be caused by the inaccuracy of the tool itself.
They also observed interplay between the traffic shaper for bandwidth limiting and the pathrate probing scheme. In some cases, they measured end-to-end capacity of 100 Mbps even though the source was bandwidth limited to 500 Kbps.