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Healing the Web: An Overview of CoDeeN & Related Projects

Healing the Web: An Overview of CoDeeN & Related Projects. Vivek Pai, Larry Peterson + many others Princeton University. How This All Started. OSDI paper on Content Distribution Network (CDN) algorithms NS-2 simulations on 8GB AlphaServer

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Healing the Web: An Overview of CoDeeN & Related Projects

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  1. Healing the Web:An Overview of CoDeeN & Related Projects Vivek Pai, Larry Peterson + many others Princeton University

  2. How This All Started • OSDI paper on Content Distribution Network (CDN) algorithms • NS-2 simulations on 8GB AlphaServer • Limits of detailed simulation – 70 hrs per experiment, huge memory requirements • Still only 1% as large as real networks • PlanetLab developed • Suddenly, can get real traffic

  3. Toward a Self-Healing Web Goals: • Improve all levels of Web infrastructure • Interoperate where possible • Drive with real traffic • Feed back measurements Client Replication Data Transfer Name Lookup Routing

  4. Cache miss Response Request Cache Miss Cache hit Cache miss Response Cache hit Request Response Data Transfer Basic CoDeeN origin CoDeeN Proxy Each CoDeeN proxy is a forward proxy, reverse proxy, & redirector

  5. Data Transfer By The Numbers… • Running 24/7 since June 2003* • Over 1 million unique IPs as clients • About 20 billion requests serviced • Over 25 million reqs/day • Highest-request project on PlanetLab • #2 in bytes/day – we serve smaller objs *not including PlanetLab Dec 2003 upgrade

  6. LAN CoDNS LDNS LDNS remote answer remote query Wide Area Network(WAN) Name Lookup CoDNS My LAN Client Programs CoDNS My Machine

  7. 99.99% 99.9% 99% Availability(%) 90% 9% 0 10 20 30 40 50 60 70 80 90 Nodes Sorted By LDNS Availability Name Lookup Availability Adds one ‘9’, from 99% to 99.9% CoDNS LDNS

  8. Name Lookup Evaluation – Live Traffic

  9. chunk2 chunk1 chunk1 chunk2 chunk1 chunk1 chunk3 chunk3 chunk5 chunk5 chunk4 chunk4 chunk5 chunk5 Replication CoBlitz CDN reverse caches the chunks! chunk1 chunk2 CDN = Redirector + Reverse Proxy CDN CDN chunk3 Client Agent CDN CDN Agent Client CDN CDN chunk5 chunk4

  10. Replication CoBlitz Performance CoBlitz users: • CiteSeer digital library • Fedora Core Linux • PlanetLab projects

  11. Routing PlanetSeer • Host service • CDN • Components • Passive monitoring • Active probing • Advantages • Low overhead • Wide coverage Client C R1 R2 B A

  12. Routing Confirmed Anomaly Breakdown Temp Anomalies 16% • Confirmed anomalies • 271,898 in 90 days • 2 per minute • 100x more Persist Loop 7% Temp loop 1% Path Change 44% Other Outage 23% Fwd Outage 9%

  13. Going Forward Cycles + bandwidth + latency qualitatively change opportunities • Obvious gains: performance, capacity, storage • Byzantine-like protocols become feasible • More time for reasoning – online failure detection, repair, recovery • Deeper analysis – better classifiers, boosting • Better security – more cycles needed for crypto, dynamic SSL

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