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IP Performance Measurements using Surveyor

Understand how Surveyor measures one-way delay and packet loss to improve Internet performance and reliability, with details on infrastructure, tools, and data analysis.

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IP Performance Measurements using Surveyor

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  1. IP Performance Measurements using Surveyor Matt Zekauskas matt@advanced.org Guy Almes, Sunil Kalidindi August, 1998 ISMA 98

  2. Outline • Background • Surveyor infrastructure • Reporting and analysis • Status

  3. I: Background • Internet topology is increasingly complex • Commonly used measurement tools (like ping and traceroute) are inadequate • Result: users don’t understand the Internet’s performance and reliability

  4. IP Performance Metrics • IETF IPPM effort • Framework RFC • One-way delay and packet loss drafts • Others: connectivity, bulk transfer, DV • Surveyor: implementation of one-way delay and packet loss metrics

  5. Motivation for measuring delay • Minimum of delay: transmission/propagation delay • Variation of delay: queuing delay • Large delay makes sustaining high-bandwidth flows harder • Erratic variation in delay makes real-time apps harder

  6. Uses • Problem determination • Engineering (trends, loads) • Feedback to advanced applications(e.g., Tele-Immersion, CMU’s Odyssey) • Monitor QoS

  7. One-way versus round trip • Paths are asymmetric • Even when paths are symmetric, forward and reverse paths may have radically different performance - asymmetric queuing

  8. II. The Surveyor Infrastructure • Measurement machines at campuses and at other interesting places along paths (e.g., gigaPoPs, interconnects) • GPS to synchronize clocks • Centralized database to store measurement data • Web based reporting and analysis tools

  9. II. Surveyor Infrastructure Measurement machines

  10. Dell 400 MHz Pentium Pro 128 MBytes RAM; 2 GBytes disk BSDI Unix TrueTime GPS card and antenna Network Interface (10/100bT, FDDI) Special driver for the GPS card Measurement Machines

  11. Measurement Technology • Active tests of one-way delay and loss • Measurement daemon • Test packets time-stamped with GPS time • Back-to-back calibration: 95% of measurements ± 50 s • Measurements centrally managed • Truer-time daemon to watch clocks

  12. Ongoing Tests

  13. Ongoing Tests - Delay • Type-P • 12 byte UDP packets, 40 bytes total • Port “random” per session • Scheduled using a Poisson Process • average rate: 2 per second • “Mostly” full mesh

  14. Ongoing Tests - Routing • Traceroute to same sites as One-Way delay • Scheduled with Poisson process • average rate: one every 10 minutes

  15. Collecting Results

  16. Central Database Machine • SGI Origin 200 • 2 processors, 256MB • 327GB Fibrechannel-attached RAIDfor data storage(DataDirect Networks EV-1000)

  17. Collects performance data from the measurement machines [ssh, pull] Stores the data in a home-grown database Serves data and summaries to reporting and analysis tools [http] Central Database Machine

  18. Current Surveyor Deployment • 28 machines, 623 paths • CSG Schools • Tele-Immersion Labs • National Labs • NASA Ames • CA*net2 Ottawa site • Auckland, NZ • …others

  19. Surveyor Map (N. America)

  20. III. Reporting and analysis tools • Web based Tools • Daily summary reports • Integration with traceroute measurements

  21. Daily summary reports Take a 24-hour sample for a given path Divide it into one-minute sub-samples For each one-minute sub-sample: Minimum delay (blue) 50th percentile (green) 90th percentile (red)

  22. Example daily reports • Advanced Network & Services and University of Chicago • path is symmetric • asymmetric queuing

  23. Examples (continued) • Advanced Network & Services and University of Pennsylvania • path asymmetric

  24. Examples (continued) • CMU to Brown University

  25. Examples - Route Change • Advanced Network & Services toPenn State University • Route change switched providers, and removed one provider from the path

  26. Examples - Auckland • University of Auckland, NZ toUniversity of Washington, Seattle • Asymmetric queuing, congested trans-pacific path

  27. IV Status • Deployment rate: 1/week • Planned: Abilene backbone • probe at each backbone router • experiment with piecewise delay

  28. Full Mesh of End-to-end Paths O(N2) paths

  29. Paths with Exchange Points O(X2+N)

  30. Abilene Router Nodes gigaPoPs Universities

  31. Near-term improvements • Improve measurement software • time stamping in-kernel: to scale without losing accuracy • New and improved analyses • real-time display tools • flag interesting paths • trends … • improved data export to other sites

  32. Summary • One-way Delay and Loss are • practical • useful • Surveyor infrastructure growing • Now focus on analysis and applications

  33. More info • Surveyor project info • http://www.advanced.org/surveyor/ • Email: mm-info@advanced.org • Access to plots • Email me - matt@advanced.org • IETF IPPM WG • http://www.advanced.org/IPPM/

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