1. 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

2. Presentation Date : 16 Nov 20052 Outline 1. Goals 2. Measurement Experience on PlanetLab 3. Measurement analysis 4. Conclusions

3. Presentation Date : 16 Nov 20053 Goals To understand the bandwidth characteristic of network paths connecting PlanetLab nodes. To obtain insights into potential trends that will enable scalable bandwidth estimation.

4. Presentation Date : 16 Nov 20054 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

5. Presentation Date : 16 Nov 20055 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.

6. Presentation Date : 16 Nov 20056 Measurement experience on PlanetLab End-to-end capacity tools  bprobe – works only on SGI Irix.  SProbe – it doesn’t report any value as detecting cross traffic.  pathrate – the only capacity estimation tool they can successfully run on Planetlab.

7. Presentation Date : 16 Nov 20057 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.

8. Presentation Date : 16 Nov 20058 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.

9. Presentation Date : 16 Nov 20059 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.

10. Presentation Date : 16 Nov 200510 Measurement Analysis End-to-end capacity statistics Set 1Set 2 No. of nodes 279178 Measurement period 8/11/04~9/6/041/5/05~1/18/05 PlanetLab version Version 2Version 3 No. of pairs 12,00621,861 Min. capacity 0.1 Mbps0.3 Mbps Max. capacity 1210.1 Mbps682.9 Mbps Ave. capacity 63.44 Mbps64.03 Mbps Median capacity 24.5 Mbps91.4 Mbps Std. deviation 119.22 Mbps43.78 Mbps

11. Presentation Date : 16 Nov 200511 Measurement Analysis End-to-end capacity statistics Capacity (C) Set 1Set 2 No. of Paths Per(%) No. of Paths Per(%) C < 20 Mbps 401333.42673330.8 20Mbps ≦ C<50Mbps 424635.3719108.74 50Mbps ≦ C<80Mbps 6745.6113035.96 80Mbps ≦ C<120Mbps 219318.271174453.72 120Mbps ≦ C<200Mbps 2071.721390.64 200Mbps ≦ C<500Mbps 3923.27210.096 500Mbps ≦ C 2812.34110.05

12. Presentation Date : 16 Nov 200512 Measurement Analysis Bandwidth capacity for all pairs measured

13. Presentation Date : 16 Nov 200513 Measurement Analysis Capacity by regions (Mbps)

14. Presentation Date : 16 Nov 200514 Measurement Analysis They define asymmetry factor between two nodes i and j, α i,j, where BW i,j is the bottleneck bandwidth from node i to node j

15. Presentation Date : 16 Nov 200515 Measurement Analysis Asymmetry factor distribution

16. Presentation Date : 16 Nov 200516 Measurement Analysis – Temporal Analysis Comparison of End-to-end capacity statistics of common node pairs in Sets1 and 2. Set 1Set 2 No. of common pairs 3,409 Measurement period 8/11/04~9/6/041/5/05~1/18/05 PlanetLab version Version 2Version 3 Min. capacity 0.1 Mbps0.5 Mbps Max. capacity 1014.1 Mbps152.6 Mbps Ave. capacity 55.79 Mbps71.09 Mbps Median capacity 24.3 Mbps97.3 Mbps Std. deviation 109.94 Mbps39.32 Mbps

17. Presentation Date : 16 Nov 200517 Measurement Analysis – Temporal Analysis End-to-end capacity distribution of common node pairs in Sets 1 and 2

18. Presentation Date : 16 Nov 200518 Measurement Analysis – Temporal Analysis Asymmetry factor distribution of common pairs in Sets 1 and 2

19. Presentation Date : 16 Nov 200519 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. Relative bandwidth correlation metric Relative bandwidth correlation penalty metric

20. Presentation Date : 16 Nov 200520 Measurement Analysis – Correlation Study Bandwidth/delay correlation

21. Presentation Date : 16 Nov 200521 Measurement Analysis – Correlation Study Cummulative distribution function of bandwidth/delay correlation Set 1.Set 2.

22. Presentation Date : 16 Nov 200522 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.

23. Presentation Date : 16 Nov 200523 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.