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Surveyor IP Performance Measurements

Surveyor IP Performance Measurements. Matt Zekauskas matt@advanced.org June, 1999 NLANR/I2 Joint Techs. IP Performance Metrics. IETF IPPM effort Framework and Connectivity RFC One-way delay and packet loss drafts Others: round-trip delay, bulk transfer, DV

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Surveyor IP Performance Measurements

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  1. Surveyor IP Performance Measurements Matt Zekauskas matt@advanced.org June, 1999 NLANR/I2 Joint Techs

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

  3. 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

  4. Uses • Problem determination • Engineering (trends, loads) • Monitor QoS • Feedback to advanced applications(for example, Tele-Immersion)

  5. 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

  6. Dell 400 MHz Pentium Pro 128 MBytes RAM; 8 GBytes disk BSDI Unix TrueTime GPS card and antenna (coax) Network Interface (10/100bT, FDDI, OC3 ATM in alpha) Special driver for the GPS card Measurement Machines

  7. 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 ± 100 s  10 s soon • Measurements centrally managed • Concurrent routing measurements

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

  9. Collects performance data from the measurement machines [ssh, pull] Stores the data in a home-grown database So far, all measurements taken on-line Serves data and summaries to reporting and analysis tools [http] Central Database Machine

  10. 50 machines Universities Tele-Immersion Labs National Labs …others 1883 paths NASA Ames XP I2 gigaPoPs (some) CA*net2 gigaPoPs APAN sites Abilene router nodes up with NTP, awaiting GPS Current Surveyor Deployment

  11. Reporting and analysis tools • Web based tools • Daily summary reports • Integration with route measurements • Java applet to dynamically graph almost ready • Developing asynchronous notification of anomalies

  12. 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)

  13. Lessons so far • Routing is asymmetric • Even when routing is symmetric,queuing is asymmetric • Can detect level 2 changes (SONET failover or ATM) • HPC connections do fall back to commodity paths, sometimes frequently or for long periods

  14. Summary • One-way Delay and Loss are • practical • useful • Surveyor infrastructure growing • Dynamic plotting, asynchronous notification coming soon • Now focus on analysis and applications

  15. More info • Surveyor project info • http://www.advanced.org/surveyor/ • Access to plots • http://ippm-db.advanced.org/plots/ • IETF IPPM WG • http://www.advanced.org/IPPM/ • My email: matt@advanced.org

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