1. Content Networking - CON Content Overlay Network Vishal Kumar Singh Eilon Yardeni April, 28 th 2005

2. Agenda Motivation Our solution – Content Overlay Network Overview Architecture Implementation Demo plan Future work Conclusions

3. Motivation Problems High access latency High network load High server load Web Caches solves this for some extent Web Cache serves localized clients On Cache miss, Web Cache access the Origin Server

4. Content Overlay Network Overview Distributing Web Caches Overlay Network of Web Caches Overlay Nodes share cached content On Cache miss, nodes access the “ closest ” node that has the object Nodes propagate cache tables Nodes perform distance measurement protocol

5. Overlay Node Overlay Node Overlay Node Overlay Node Client Overlay Node Origin Server Client GET Object A GET Object A Lookup in local Cache Lookup in “adjacent” nodes Cache Fetch from Adjacent node Serve client Architecture A Lookup in local Cache Lookup in “adjacent” nodes Cache Fetch from Origin Server Serve client A Propagate cache table update

6. Content Overlay Network Implementation Distance Measurement Protocol UDP based RTT measurements n 2 measurements Performed in the background Cache table propagation Each node periodically propagates its cache table diffs to all the other nodes

7. Content Overlay Network Implementation (Cont.) On Cache miss Lookup in local cache table If found serve the client Lookup in “ adjacent ” nodes cache tables If found and distance is smaller than a threshold: fetch content from node and serve the client Update local cache if required Access the Origin Server Update local cache and serve the client

8. Demo plan 3 overlay nodes: A,B and C Browser use A as a proxy Cache miss updates A ’ s cache Browser use B as a proxy Cache miss fetch object from A

9. Future work Measure distance to Origin Servers Integrate with open-source Web Cache Use DNS measurements Overlay bootstrap protocol Overtake Akamai …

10. Open discussion