1. Cooperative Overlay Networking for Streaming Media Content Feng Wang 1, Jiangchuan Liu 1, Kui Wu 2 1 School of Computing Science, Simon Fraser University {fwa1, jcliu}@cs.sfu.ca 2 Department of Computer Science, University of Victoria wkui@cs.uvic.ca Chapter 6 Cooperative Networking (Wiley) Editors: M. S. Obaidat and S. Misra

2. 2 Outline Background and Motivation A Cooperative Overlay Design: mTreebone Treebone Construction and Optimization Collaborative Push/Pull Data Delivery Performance Evaluation Conclusion and Future Work

3. 3 Background Architectural Choices for Media Streaming IP Multicast Implement multicast at the IP (network) layer Multicast routing is the most efficient Limited in reach and scope due to concerns regarding scalability, deployment, and support for higher level functionality Proxy Caching Exploits the temporal locality of client requests for streaming media content

4. 4 Background (cont ’ d) Deploy a group of proxies to cooperatively utilize caching space, balance loads and improve the overall performance Peer-to-Peer Functionality is pushed to users actually participating in the multicast group Administration, maintenance, responsibility for operations of a system are distributed among users Research focuses on simultaneous media broadcast using the application end-point architecture

5. 5 Motivation Previous proposals for Peer-to-Peer Media Streaming can be broadly classified into two categories Tree-based approaches Peers are organized into structures (typically trees) for delivering data Each data packet is pushed using the same structure Nodes on the structure have well-defined relationships, e.g., “ parent-child ” relationships in trees

6. 6 Motivation (cont ’ d) Mesh-based approaches Do not construct or maintain an explicit structure for delivering data Use the availability of data to guide the data flow Based on data availability information periodically exchanged among partner nodes, a node may then retrieve unavailable data from other partners, or supply available data to other partners

7. 7 Motivation (cont ’ d) Different category of approaches have different advantages Mesh-based approaches have good robustness, but suffer from the efficiency-latency tradeoff Tree-based approaches use efficient push delivery, but have to face data outage during internal node dynamics. Can we combine their advantages together to offer high efficiency and resilience with moderate maintenance cost?

8. 8 Our Idea - mTreebone Hybrid Cooperative Tree/Mesh Overlay Organize stable nodes as a tree backbone (Treebone) to efficiently deliver data Mesh overlay assists Treebone and handles dynamics

9. 9 Questions How to identify stable nodes? How to better organize these nodes? How to reconcile Treebone and mesh overlay?

10. 10 Questions How to identify stable nodes? How to better organize these nodes? How to reconcile Treebone and mesh overlay?

11. 11 Previous studies: nodes with higher ages tend to stay longer Select an Age Threshold T and consider nodes staying longer than T as stable Objective: maximize the Expected Service Time of a Treebone node For Pareto Dist. (with k as shape parameter) Stable Node Identification

12. 12 Treebone Evolution Each new node attaches to a node with available bandwidth Non-Treebone nodes check periodically until promoted into Treebone 0 0 5 5 7 6 17 10 6 11 8 17 12

13. 13 Questions How to identify stable nodes? How to better organize these nodes? How to reconcile Treebone and mesh overlay?

14. 14 Treebone Optimization Reduce average depth of Treebone node High-Degree-Preemption Low-Delay-Jump Theorem The average depth of Treebone is minimized when high-degree-preemption and low-delay-jump terminate at all Treebone nodes.

15. 15 Questions How to identify stable nodes? How to better organize these nodes? How to reconcile Treebone and mesh overlay?

16. 16 Seamless Push/Pull Switching Tree-push pointer receives data pushed from Treebone Mesh-pull window detects loss and pull data from mesh neighbors To avoid duplicate data, mesh-pull window always keeps behind Tree-push pointer Tree-push PointerPlayback Pointer Mesh-pull Window Playback Direction

17. 17 Outline Introduction mTreebone Design Treebone Construction and Optimization Collaborative Push/Pull Data Delivery Performance Evaluation Conclusion and Future Work

18. 18 Performance Evaluation Scenario Arrival: Poisson dist. Duration: Pareto dist. Simulations 5000 nodes Prototype Experiments on PlanetLab 200 nodes

19. 19 Simulation Results Data Loss RateStartup LatencyPlayback Delay

20. 20 Experiment Results Data Loss RateStartup LatencyPlayback Delay

21. 21 Experiment Results (cont ’ d) Control OverheadDifferent Age ThresholdDifferent Churn Rate

22. 22 Outline Introduction mTreebone Design Treebone Construction and Optimization Collaborative Push/Pull Data Delivery Performance Evaluation Conclusion and Future Work

23. 23 Conclusion mTreebone: a hybrid cooperative overlay taking advantages of both tree and mesh Treebone by stable nodes to offer high efficiency; mesh structure to improve the robustness Threshold based Treebone nodes selection Treebone construction and optimization Seamless push/pull switching buffer

24. 24 Future Work Other tree organization and optimization methods to further improve Treebone ’ s efficiency and interactions with mesh Multi-tree-based backbone, which may lead to more balanced load and finer-grained bandwidth control Conduct large scale experiments as well as real deployment over global Internet