1. Peer-to-Peer Media Streaming ZIGZAG - Ye Lin PROMISE – Chanjun Yang SASABE - Kung-En Lin

2. Video Streaming Solutions Dedicated Channel: individual connection to each receiver – Unicast (server bottleneck) IP Multicast: Synchronized peers problem. Server C1C1 C2C2 … C n-1 CnCn Server C1C1 C2C2 C n-1 CnCn …

3. Chaining Basic Idea A client can forward its incoming video stream to serve other clients Advantages Each client can now contribute its computing resource to serve the entire community, rather than being just a burden to some central server A new client can be chained to an early client, making this service model highly scalable It uses only unicast, but achieves the same effect of using IP multicast Since each server stream now can serve many clients, this strategy is often called Application Layer Multicast. Server C1 C2 C3

4. Chaining Problems End-to-end delay Tree height: If a tree is too long, the forwarding delay will be large, making it unsuitable for live streaming Node degree: If a node has high degree, high forwarding bandwidth is required Robustness requirement A receiver may join and leave at any time If a forwarding client leaves, its downstream clients must be hooked to some other clients Assume peers are indifference Different bandwidth Different capacity

5. Solutions ZIGZAG Short End-to-End delay Efficient join and failure recovery PROMISE Aggregate peers bandwidth SASABE QoS consideration and Efficient distribution

6. ZIGZAG: An Efficient Peer-to-Peer Scheme for Media Streaming Ye Lin

7. Proposed ZIGZAG Administrative organization

8. ZIGZAG Multicast tree A peer, when not at its highest layer, can not have links to or from any other peers. A peer, when at its highest layer, can only link to its foreign subordinates. The only exception is the server. At layer j<H-1, peer get the content directly from a foreign head.

9. ZIGZAG Control protocol thru periodic communication: clustermates, children and parent. Peer join: link node to the leaf cluster that have minimum end-to-end delay.

10. ZIGZAG Peer fails The parent of X delete the link to X. Y, the cluster head of X ‘s children, is responsible for finding a new parent for X ‘s children. X’, A random subordinate of X at layer 0 become new head of each cluster that lost X X’ gets link from X ‘s parent.

11. ZIGZAG Performance Evaluation ZIGZAGNICE Node degree O(k 2 )O(logN) Height of multicast tree O(log k N)O((log k N) 2 ) Control overhead of a node O(k*log k N)O(k*logN) Join overhead O(log k N)O(logN) Split overhead O(k 2) Number of peers that need to reconnect due to a failure O(k 2) O(log k N) Merge overhead O(k 2)

12. ZIGZAG Conclusion Major innovation use of a foreign head to forward the content. Desirable properties short end-to-end delay efficient join and failure recovery

13. PROMISE: Peer-to-Peer Media Streaming Using CollectCast Chanjun Yang

14. Introduction to the Problem Challenges of P2P real-time media streaming A sender may stop contributing to a P2P session The connections may have different bandwidth, loss and failure rate The connections between the senders and receiver are not independent Maintain the best possible streaming quality Select, monitor and possibly switch sending peers

15. Relative Work One sender, one receiver The sender may not have enough capability Receive data from multiple senders Do not select best senders Ignores peer diversity and network conditions

16. Proposed PROMISE Selects best sending peers. Monitors the senders and network status. Chooses new senders when trouble occurs.

17. PROMISE - Architecture P2P substrate Independent from PROMISE CollectCast A novel application level P2P service Middleware between a lookup substrate and applications PROMISE

18. PROMISE - Operations Send lookup request to the substrate for a media file. Determine the set of active senders and passive senders. Active senders are the best choices The receiver assigns a sending rate to the active senders based on certain parameters. Transmission continues unless a switch is needed. A peer from the passive set is swapped in to the active set.

19. PROMISE – Selecting Best Senders Random Randomly chooses a number of peers End-to-end Estimates the “goodness” of the path from each candidate peer to the receiver Topology-aware Infers the underlying topology and its characteristics and considers the goodness of each segment of the path

20. Selecting Senders – End-to- end selection Based on quality of paths Does not consider shared segment If peers sharing a tight segment are chosen in the active set ?

21. Selecting Senders – Topology- Aware Selection Build the goodness topology Use the goodness topology to estimate the peer goodness for the session Formulate the peer selection problem as an optimization problem

22. Topology-Aware Selection – Goodness Topology Build the inferred topology Infer the approximate topology Annotate its edges with the metrics of interest. (e.g., loss rate and available bandwidth) Transform to the goodness topology Compute a “logical” goodness metric for each segment based on the metrics annotated

23. Topology-Aware Selection – Segment Goodness For each peer p chosen as an active peer, The goodness of segment i  j : g i  j = w i  j x i  j w i  j depends on the available bandwidth and level of sharing on segment i  j. x i  j depends on the loss rate. The mean of x i  j : E (x i  j ) = 1- average loss rate on i  j.

24. Topology-Aware Selection – Segment Goodness (Cont’d) W i  j = 1 : aggregate rate of the peers sharing the segment <= available bandwidth. Otherwise, it is proportioned to the shortage of bandwidth if the peer is chosen with the already selected peers. W i  j = ( b i  j - ∑ s ∈ S, i  j ∈ s  r R s ) / R p

25. Topology-Aware Selection – Peer Goodness The goodness of each peer, G p depends on goodness of all segments on the path from the peer to the receiver availability of the peer

26. Topology-Aware Selection – Peer Goodness (Cont’d) Peers with a goodness of close to 1: Good availability Reliable path Therefore we expect they would be a good choice for sender

27. Topology-Aware Selection - Algorithm Enumerate all possible sets satisfying the constraint Select the one with the highest rate

28. Topology-Aware Selection - Example {P4, P6}, {P3, P5, P6},… {P2, P3, P6},…{P1, P2, P3, P5} E({P3, P5, P6}) = 1 x.8 x.25 + 1 x.8 x.25 + (.25 /.50) x.9 x.5 = 0.625 E({P2, P3, P6}) = 1 x.7 x.25 + 1 x.8 x.25+ 1 x.9 x.5 = 0.825 Set loss rate in all path = 0 E (x i->j ) = 1 for all i,j Set R l = R U = R 0 = 1 Mb/s R 0 : The playback rate

29. PROMISE – Rate and Data Assignment A media file is divided into equal-length segments. The active peers collectively send the media file segment by segment. Rate assignment: Each peer p is assigned an actual sending rate R p proportional to its offered rate. Data assignment: Each peer is assigned a number of packets D p to send in proportion to its actual streaming rate

30. PROMISE – Dynamic Switching Peers may fail or network paths may become congested during a long streaming session Once a failure is detected, replacement peers will be selected by using the topology-aware selection

31. PROMISE – Performance Evaluation

32. PROMISE – Performance Evaluation (Cont’d)

33. PROMISE Conclusion PROMISE Multiple sender peers, single receiver peer Select, monitor, and switch sending peers CollectCast Infer and exploit topology and performance Realizing the functions of sender selection, monitoring, and switching PROMISE delivers high quality streaming and is resistant to peer failure when using the topology aware technique.

34. Scalable and Continuous Media Streaming on Peer-to-Peer Networks Kung-En Lin

35. Introduction to the Problem P2P Application Layer Multicast tree Root peer is an original media server. Other peers are intermediate nodes and leaves. Peers’ demands are simultaneous and concentrated on a specific media stream. (Effective) A variety of media streams. (Problem)

36. Relative Work PROMISE Selection of Senders Calculating parameter based on entire media stream Constant monitoring of sender/network status Switching of senders when the sender or network fails

37. Proposed solution Segmentation of media stream Two scalable methods to find desired media block Two algorithms to determine an optimum provider peer from the search results

38. Basic concept – Media block A “block” is a processing unit that can be encoded and decoded by itself. Example: A multiple of the GoP (Group of Pictures) of MPEG-2 The number of blocks of a media stream affects the system scalability in terms of the amount of search traffic.

39. Per-group search

40. Searching Mechanism Full flooding Gnutella, Freenet Limited Flooding control by TTL Selective Search FL method FLS method

41. Selective Search FL method Satisfy – Limited flooding Otherwise, Full flooding FLS method Selective – peers contain all of the next round’s blocks. Limited – Missing one of next round’s block. Full flooding – Missing all of next round’s blocks.

42. Determination algorithm p1 p2 p3 p5 p6 p8 p9 p… Block 1 p5 p8 p11 p3 p4 p9 p10 p20 Block 2 Block 3 S

43. Determination algorithm t1 t2 t3 t5 t6 t8 t9 t… S’ Time = max(A, B) + size of block / bandwidth of the peer A: Estimated completion time of retrieval of the block B: Time when this algorithm is performed + Round trip time of the peer > deadline of the block?

44. Determination algorithm t1 t2 t5 t6 t… S’ SF method (Selected Fasted) Smallest completed time SR method (Selected Reliable) Lowest possibility of black disappearance. Largest number

45. Determination algorithm Recalculating retrieval time and request block from the peer which we selected If we have done all of blocks, we finish determination algorithm. Otherwise, repeat the first step to get next block.

46. Performance Evaluation

47. Performance Evaluation (Cont’d)

48. Conclusion FLS method provide users with continuous media play-out without introducing extra load on the system. Unpopular media streams did not really fulfill FLS method. QoS is a trade-off of scalability.

49. Conclusion – P2P Streaming Application Layer Multicast Tree reconstructing (one-to-multi) Resource aggregating (multi-to-one) P2P Video Scheduling P2P Video System