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ACM SIGCOMM Workshop on Measurements         Up and Down the Stack (W-MUST) 2012Estimating Packet Loss Rate in theAccess T...
Rewind: Nexa Center and earlier      studies on network neutrality ●   Nexa Center: academic research center that     stud...
Neubot: the network neutralitybot (active application-level tests) ●   Neubot is a daemon that runs in the background and ...
Rationale and issues of     application-level measurements ●   Application-level tests are appealing because they are     ...
Idea: estimate packet loss rate       and use it for comparison ●   We propose to invert the Mathis formula, to     estima...
Step #1: evaluation in a                  testbed environment17 August 2012         Simone Basso – Politecnico di Torino   6
Testbed experiments results17 August 2012   Simone Basso – Politecnico di Torino   7
Step #2: evaluation with    controlled Internet experiments17 August 2012   Simone Basso – Politecnico di Torino   8
Controlled experiments results17 August 2012   Simone Basso – Politecnico di Torino   9
Step #3: evaluation in testbed     emulating an ADSL connection17 August 2012   Simone Basso – Politecnico di Torino   10
Results of testbed emulating           an ADSL connection17 August 2012   Simone Basso – Politecnico di Torino   11
Conclusion and future work ●   It seems good enough for coarse grained     classification of application level performance...
Thank you for your attention!          Simone Basso (simone.basso@polito.it)        Nexa Center for Internet & Society (ht...
Appendix: Mathis formula ●   MSS is the maximum segment size ●   C is 0.93 for random losses and delayed ACKs ●   RTT is t...
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Estimating Packet Loss Rate in the Access Through Application-Level Measurements

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Presentation of the paper "Estimating Packet Loss Rate in the Access Through Application-Level Measurements", co-authored with Michela Meo, Antonio Servetti and Juan Carlos De Martin

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Estimating Packet Loss Rate in the Access Through Application-Level Measurements

  1. 1. ACM SIGCOMM Workshop on Measurements Up and Down the Stack (W-MUST) 2012Estimating Packet Loss Rate in theAccess Through Application-Level Measurements +S.Basso* M.Meo A.Servettiǂ J.C.De Martin* *Nexa Center for Internet & Society, DAUIN, Politecnico di Torino +DET, Politecnico di Torino ǂDAUIN, Politecnico di Torino Helsinki, 17 August 2012
  2. 2. Rewind: Nexa Center and earlier studies on network neutrality ● Nexa Center: academic research center that studies the Internet from a multidisciplinary point of view (technology, law, economics) ● January 2009 – legal analysis of 10 wired and 4 wireless Italian broadband ISPs contracts (http://bit.ly/GQ6FEK) ● Decision to develop a software research project to monitor network neutrality: Neubot (http://neubot.org)17 August 2012 Simone Basso – Politecnico di Torino 2
  3. 3. Neubot: the network neutralitybot (active application-level tests) ● Neubot is a daemon that runs in the background and periodically performs active tests towards servers provided by Measurement Lab (http://measurementlab.net) ● Tests probe the end-to-end path between the user and the server (including at least access and home network), aim at saturating the bottleneck, run for a short amount of time (5- 10 s), emulate HTTP and BitTorrent, and perform goodput and RTT measurements at application level ● Results are centrally collected, providing an application- level characterization of what one can see, from the user vantage point, using different protocols17 August 2012 Simone Basso – Politecnico di Torino 3
  4. 4. Rationale and issues of application-level measurements ● Application-level tests are appealing because they are simple, scalable and portable to other contexts ● Unfortunately, a lot of very useful packet-level information is missing (e.g. retransmissions and other TCP events) ● Of course, one cannot just compare (as in “which one is better from the point of view of a human?”) two measurements by the goodput alone, because the goodput is inversely proportional to the RTT17 August 2012 Simone Basso – Politecnico di Torino 4
  5. 5. Idea: estimate packet loss rate and use it for comparison ● We propose to invert the Mathis formula, to estimate the packet loss rate (PLR) from RTT, goodput and maximum segment size (MSS) ● In turn, the comparison between two measurements will be performed in the bidimensional (RTT, PLR) space ● The question is whether the estimation is sufficiently robust, given that we are not working in ideal conditions (e.g. short tests, simple RTT estimation)17 August 2012 Simone Basso – Politecnico di Torino 5
  6. 6. Step #1: evaluation in a testbed environment17 August 2012 Simone Basso – Politecnico di Torino 6
  7. 7. Testbed experiments results17 August 2012 Simone Basso – Politecnico di Torino 7
  8. 8. Step #2: evaluation with controlled Internet experiments17 August 2012 Simone Basso – Politecnico di Torino 8
  9. 9. Controlled experiments results17 August 2012 Simone Basso – Politecnico di Torino 9
  10. 10. Step #3: evaluation in testbed emulating an ADSL connection17 August 2012 Simone Basso – Politecnico di Torino 10
  11. 11. Results of testbed emulating an ADSL connection17 August 2012 Simone Basso – Politecnico di Torino 11
  12. 12. Conclusion and future work ● It seems good enough for coarse grained classification of application level performance ● The estimated PLR depends on the connection speed (so that a “better” connection for the user gets a lower PLR estimate) ● The estimated PLR still depends on the RTT: does running tests with higher RTT for longer times mitigates the problem? ● Does the model work reasonably for request- response application-level patterns?17 August 2012 Simone Basso – Politecnico di Torino 12
  13. 13. Thank you for your attention! Simone Basso (simone.basso@polito.it) Nexa Center for Internet & Society (http://nexa.polito.it/) Dept. of Computer and Control Engineering (DAUIN) Politecnico di Torino, Italy The Neubot project (http://neubot.org/) http://twitter.com/neubot http://facebook.com/neubot17 August 2012 Simone Basso – Politecnico di Torino 13
  14. 14. Appendix: Mathis formula ● MSS is the maximum segment size ● C is 0.93 for random losses and delayed ACKs ● RTT is the round trip time ● PLR is the packet loss rate17 August 2012 Simone Basso – Politecnico di Torino 14

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