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

2. Jan 30, 2006 - GENI visit2 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. Jan 30, 2006 - GENI visit3 Toward a Self-Healing Web Goals: Improve all levels of Web infrastructure Interoperate where possible Drive with real traffic Feed back measurements Routing Name Lookup Data Transfer Replication Client

4. Jan 30, 2006 - GENI visit4 Basic CoDeeN CoDeeN Proxy origin Request Response Cache hit Each CoDeeN proxy is a forward proxy, reverse proxy, & redirector Cache miss Response Cache hit Cache miss Response Request Cache Miss Data Transfer

5. Jan 30, 2006 - GENI visit5 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 Data Transfer

6. Jan 30, 2006 - GENI visit6 Wide Area Network(WAN) CoDNS My LAN LAN LDNS CoDNS My Machine LDNS remote answer Client Programs remote query Name Lookup

7. Jan 30, 2006 - GENI visit7 Availability Adds one ‘9’, from 99% to 99.9% CoDNS LDNS Name Lookup

8. Jan 30, 2006 - GENI visit8 Evaluation – Live Traffic Name Lookup

9. Jan 30, 2006 - GENI visit9 CoBlitz AgentCDNClient CDN reverse caches the chunks! CDN ClientAgent CDN chunk1 chunk2 chunk3 chunk2 chunk5 chunk1 chunk4 chunk5 chunk1chunk2 chunk3 chunk4 chunk5 CDN = Redirector + Reverse Proxy Replication

10. Jan 30, 2006 - GENI visit10 CoBlitz Performance CoBlitz users: CiteSeer digital library Fedora Core Linux PlanetLab projects Replication

11. Jan 30, 2006 - GENI visit11 PlanetSeer Host service CDN Components Passive monitoring Active probing Advantages Low overhead Wide coverage Client A C B R1 R2 Routing

12. Jan 30, 2006 - GENI visit12 Confirmed Anomaly Breakdown Confirmed anomalies 271,898 in 90 days 2 per minute 100x more Temp loop 1% Path Change 44% Fwd Outage 9% Other Outage 23% Persist Loop 7% Temp Anomalies 16% Routing

13. Jan 30, 2006 - GENI visit13 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