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The Practicality of End-User Network Monitoring by Vivek Pai, Princeton University

Explore the evolution of network monitoring with Vivek Pai from Princeton University, covering the beginnings with RON to PlanetLab and the innovative approach of PlanetSeer. Discover the challenges, solutions, and future of end-user network monitoring.

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The Practicality of End-User Network Monitoring by Vivek Pai, Princeton University

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  1. The Practicality of End-User Network Monitoring Vivek Pai Princeton University

  2. What Is This Talk? • Gedankenexperiment • A brief history of work – ours & related • Not necessarily precise • Not even close to exhaustive • Some prediction, direction • From discussions with Ming Zhang, Larry Peterson • Much derived from Ming’s PlanetSeer work Vivek Pai, Princeton University

  3. In The Beginning • There was RON • And RON was good But • RON was smaller than the Internet Vivek Pai, Princeton University

  4. And Then There Was PlanetLab • PlanetLab was bigger • But still smaller than the Internet • But it was growing • What about RON on PlanetLab? Vivek Pai, Princeton University

  5. Other Problems • All-pairs probing not indefinitely scalable • Possible to modify this • Path diversity was a problem • No quadratic increase in diversity with additional nodes • Every reviewer would jump on this • Still not growing fast enough Vivek Pai, Princeton University

  6. Idea: Use “External” Nodes • Two groups had similar ideas • SOSR (Gummadi et al) and • PlanetSeer (Zhang et al) • Both published in OSDI 2004 • Approach specifics differed • Probe type, probe frequency • # of participating nodes, etc Vivek Pai, Princeton University

  7. SOSR Target popular web servers Actively probe at periodic intervals TCP probes PlanetSeer Target clients & servers Passively monitor, then actively probe UDP (traceroute) Host: CoDeeN CDN http://codeen.cs.princeton.edu Quick Highlights Vivek Pai, Princeton University

  8. High-Level Picture of PlanetSeer Vivek Pai, Princeton University

  9. TTL 30 TTL 32 TTL 28 TTL 31 TTL 29 TTL 32 TTL 29 TTL 31 TTL 30 When To Probe? • Difficulties • Do not continuously probe • No cooperation from both ends • Indicators of routing problem • Time-to-live (TTL) change • n consecutive timeouts (currently n = 4) • Idling period of 3 to 16 seconds • Congestions usually don’t last this long? source destination

  10. Probing Groups • 353 nodes, 145 sites, 30 groups world-wide • Reduce overhead without losing accuracy • One traceroute from each group

  11. Temp Anomaly 16% Persist Loop 7% Path Change 44% Temp Loop 1% Other Outage 23% Fwd Outage 9% Confirmed Anomaly Breakdown • Confirmed anomalies • 271,898 • 3 months • 2 per minute • 100 x higher • Temp anomaly • Inconsistent probe

  12. PlanetSeer Tradeoffs • Passive/active big win • One active probe on avg every 4 seconds • Understanding NATs drops this to every 8 secs • One confirmed anomaly every 30 seconds • About 100x the anomalies for 3x probe traffic • Using external loses some info • But passive traffic provides some Vivek Pai, Princeton University

  13. Core Edge 215 ASes 22 ASes 1392 ASes 1420 ASes 13872 ASes Path Diversity • Monitoring period: 02/2004 – 05/2004 • Unique IPs: 887,521 • Traversed ASes: 10,090 Vivek Pai, Princeton University

  14. PlanetSeer Going Forward • CoDeeN traffic increasing • Was doing ~5M reqs/day from ~25K clients • Now at 12M+ reqs/day from 50K+ clients • Coverage might be improving • PlanetSeer saw ~1M unique IP addresses in 3 months • Not clear how many are dial-up • New users will come from new services, like CoBlitz (scalable large-file transfer) Vivek Pai, Princeton University

  15. Observations • Getting 2 orders larger than RON required new approach • PlanetSeer has several avenues for growth • Missing half of Tier 5 ASes • More traffic on lower tiers desirable • Total users still small • Projection: next 2 orders will need new approach Vivek Pai, Princeton University

  16. Involving the End User • Seti@home approach • About 5M downloads • In comparison: CNN 22M, AOL 23M • Web bugs • Possible, but who’s going to do it? • P2P probing • Public relations problem? Maybe • BitTorrent/Skype likely candidates – how? • Locality optimizations undesirable Vivek Pai, Princeton University

  17. MeasureMe! • Use browser to launch active probes • Like web bugs, but obvious • Delivery options • Built into browser • Clickable via error pages • Toolbar • Local application (screen saver, etc.) Vivek Pai, Princeton University

  18. Each image URL is for a CGI, and has an identifier Vivek Pai, Princeton University

  19. Do We Need End Users? • Most people not multi-homed • Last mile does not matter • Matters to them, but not otherwise • Focus on ISPs • Fewer privacy, security issues • Can ship data with other routing data • End users useful when ISP not joining Vivek Pai, Princeton University

  20. Do We Need To Coalesce? • Measurement traffic still small • Good experience for students • New ideas needed • Different approaches may yield new insight • Shared measurement infrastructure vulnerable • Blacklisting affects more people • Any experiment can cause ripples Vivek Pai, Princeton University

  21. What’s Next For Us • We’ll let PlanetSeer track CoDeeN • User growth will give us more data • Long (1GB+) downloads in CoBlitz will provide more stickiness • Might implement MeasureMe! splash screen • Longer term – allow direct participation Vivek Pai, Princeton University

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