1. Climber extension with Multiple Description Coding (MDC) Kunwoo Park Seoul National University, Korea

2. Live Streaming Services MSN broadcast –http://liveearth.msn.com 2/12

3. Outline Live Streaming Services Climber MDC Climber + MDC 3/12

4. Live Streaming Services Cost –Building a CDN costs too much –Encourage peers to contribute to the system Resilience –Live Earth concert in July 2007 rated 237,000 simultaneous viewers at the peak –A system should work in the presence of high churn Delay –Live streaming is not like that of file downloading service –Packets should be delivered in time 4/12

5. Climber An Incentive-based Resilient P2P System for Live Streaming Services A hybrid of a tree and a mesh –Tree - main structure, forward streaming –Mesh - enhance resilience by redundant edges Random Edge Design concepts –Incentive –Resilience 5/12

6. Random Edge? A directed edge to a random peer –Only the sequence number of the stream is sent along a random edge For each available outdegree, a node makes a random edge with low probability 6/12 0 1 3 2 4 5 Random edge

7. 7/12 A node climbs a tree by a Random Edge 3 congested/failed node random edge Node 7 climbs the tree by being a child of node 2 Climber greatly simplifies the recovery procedure caused by node failures Actually, Climber does not distinguish node failure from node congestion

8. Multiple Description Coding A coding technique –fragments a stream into k sub streams (k>=2) The more sub streams received, the higher the quality –roughly proportional to # of sub streams –any subset of these sub streams can be decoded 8/12

9. Climber + MDC In Climber, only header information are sent via random edges Climbers multipath delivery concept naturally fits with MDC What if we send a sub stream as a random edge –Improved resilience with much more bandwidth consumption 9/12

10. Need a prediction mechanism 10/12 123123 1212 I am receiving 1, 2, 3. If I send only 1, 2, will my descendants receive 3 through random edges? 134134 4 3 sub stream 1, 2, 3, 4 1,2,3,4

11. 11/12 Summary Climber –The 7th International Workshop on Peer-to- Peer Systems (IPTPS '08) MDC Climber + MDC Ongoing work

12. Thank you Any questions? 12/12