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    1. 1. P2P On-Demand Video Streaming and Caching 丁建文 高雄應用科大資管系
    2. 2. Outline <ul><li>Motivation </li></ul><ul><li>Introduction </li></ul><ul><li>On-Demand Streaming and Caching </li></ul><ul><li>Conclusions </li></ul>
    3. 3. Motivation (1) <ul><li>Different approaches for video streaming </li></ul><ul><ul><li>Client/Server architecture </li></ul></ul><ul><ul><ul><li>IP-Unicast solution </li></ul></ul></ul><ul><ul><ul><ul><li>Non scalable </li></ul></ul></ul></ul><ul><ul><ul><li>IP-Multicast solution </li></ul></ul></ul><ul><ul><ul><ul><li>Most ISPs do not support </li></ul></ul></ul></ul><ul><ul><li>CDN architecture </li></ul></ul><ul><ul><ul><li>Replicate servers + multiple proxies </li></ul></ul></ul><ul><ul><ul><ul><li>Too expensive </li></ul></ul></ul></ul><ul><ul><li>P2P architecture </li></ul></ul><ul><ul><ul><li>AP-level multicast </li></ul></ul></ul><ul><ul><ul><ul><li>Scalable and cheap </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Unstable </li></ul></ul></ul></ul><ul><ul><li>Hybrid architecture </li></ul></ul><ul><ul><ul><li>CDN+P2P </li></ul></ul></ul>
    4. 4. Client-Server Streaming Architecture Yiu, W.-Pk.; Xing Jin; Chan, S.-H.G., &quot;Challenges and Approaches in Large-Scale P2P Media Streaming,&quot; Multimedia, IEEE , vol.14, no.2, pp.50-59, April-June 2007
    5. 5. CDN-Based Streaming Architecture Yiu, W.-Pk.; Xing Jin; Chan, S.-H.G., &quot;Challenges and Approaches in Large-Scale P2P Media Streaming,&quot; Multimedia, IEEE , vol.14, no.2, pp.50-59, April-June 2007
    6. 6. P2P Streaming Architecture Yiu, W.-Pk.; Xing Jin; Chan, S.-H.G., &quot;Challenges and Approaches in Large-Scale P2P Media Streaming,&quot; Multimedia, IEEE , vol.14, no.2, pp.50-59, April-June 2007
    7. 7. Motivation (2) <ul><li>Advantages of P2P streaming </li></ul><ul><ul><li>Huge storage </li></ul></ul><ul><ul><ul><li>Each user contribute some storage space </li></ul></ul></ul><ul><ul><ul><li># of users may be 1000, 10,000, 100,000, … </li></ul></ul></ul><ul><ul><li>Huge bandwidth </li></ul></ul><ul><ul><ul><li>Each user contribute some forwarding bandwidth </li></ul></ul></ul><ul><ul><ul><li># of users may be 1000, 10,000, 100,000, … </li></ul></ul></ul><ul><ul><li>Very light load on server </li></ul></ul><ul><ul><li>Distributed load on network </li></ul></ul>
    8. 8. Outline <ul><li>Motivation </li></ul><ul><li>Introduction </li></ul><ul><li>On-Demand Streaming and Caching </li></ul><ul><li>Conclusions </li></ul>
    9. 9. Introduction <ul><li>P2P streaming is very popular now </li></ul><ul><li>Famous examples: </li></ul><ul><ul><li>PPLive </li></ul></ul><ul><ul><ul><li>http://www.pplive.com/ </li></ul></ul></ul><ul><ul><li>PPStream </li></ul></ul><ul><ul><ul><li>http://www.ppstream.com/ </li></ul></ul></ul>
    10. 10. Introduction <ul><li>Types of P2P streaming </li></ul><ul><ul><li>Live P2P streaming </li></ul></ul><ul><ul><ul><li>Example: traditional TV channel, live sport event </li></ul></ul></ul><ul><ul><ul><li>Many users share a stream </li></ul></ul></ul><ul><ul><ul><li>Less challenge </li></ul></ul></ul><ul><ul><li>On-demand P2P streaming </li></ul></ul><ul><ul><ul><li>Example: Movie-on-demand </li></ul></ul></ul><ul><ul><ul><li>Each user is allocated a stream </li></ul></ul></ul><ul><ul><ul><li>More challenge </li></ul></ul></ul>
    11. 13. Two Main Design Issues <ul><li>How to locate peers? </li></ul><ul><li>How to deliver data to peers? </li></ul>
    12. 14. How to locate peers? <ul><li>Centralized search </li></ul><ul><li>Hierarchical search </li></ul><ul><li>Flooding-based search </li></ul><ul><li>DHT-based search </li></ul>
    13. 15. How to locate peers? <ul><li>Centralized Approach </li></ul>Yiu, W.-Pk.; Xing Jin; Chan, S.-H.G., &quot;Challenges and Approaches in Large-Scale P2P Media Streaming,&quot; Multimedia, IEEE , vol.14, no.2, pp.50-59, April-June 2007 Examples: PPStream, PPLive
    14. 16. How to locate peers? <ul><li>Hierarchical Search </li></ul><ul><ul><li>Zigzag, Nice, P2Cast, P2VoD </li></ul></ul>Tran, D.A.; Hua, K.A.; Do, T.T., &quot;A peer-to-peer architecture for media streaming,&quot; Selected Areas in Communications, IEEE Journal on , vol.22, no.1, pp. 121-133, Jan. 2004
    15. 17. How to locate peers? <ul><li>Hierarchical Search – Zigzag </li></ul><ul><ul><li>Zigzag organizes receivers into a hierarchy of clusters </li></ul></ul><ul><ul><li>A cluster has a head and an associate head </li></ul></ul><ul><ul><ul><li>Head is responsible for monitoring the memberships of the cluster </li></ul></ul></ul><ul><ul><ul><li>Associate-head is responsible for transmitting the content to cluster members. </li></ul></ul></ul><ul><ul><ul><li>The failure of the head does not affect the service continuity of other members </li></ul></ul></ul><ul><ul><ul><li>Or in case the associate-head departs, the head is still working and can designate a new associate-head quickly </li></ul></ul></ul>
    16. 18. How to locate peers? <ul><li>Hierarchical Search – Zigzag </li></ul><ul><ul><li>A peer X do the following when receiving a joining request from a new client </li></ul></ul>D(Y): delay between server and Y d(Y,P): delay between Y and P Tran, D.A.; Hua, K.A.; Do, T.T., &quot;A peer-to-peer architecture for media streaming,&quot; Selected Areas in Communications, IEEE Journal on , vol.22, no.1, pp. 121-133, Jan. 2004 By doing so, nearby peers are grouped together, making the data transmission based on that structure efficient!
    17. 19. How to locate peers? <ul><li>Flooding-Based Approach (1) </li></ul><ul><li>Example: </li></ul><ul><li>GnuStream </li></ul><ul><li>Gnutella Protocol: </li></ul><ul><li>Query message sent over existing TCP connections </li></ul><ul><li>Peers forward query message </li></ul><ul><li>The query message is associated with a time-to-live (TTL) value. </li></ul><ul><li>QueryHit sent over reverse path </li></ul>Computer Networking: A Top Down Approach, 4th edition. Jim Kurose, Keith Ross, Addison-Wesley, July 2007.
    18. 20. How to locate peers? <ul><li>Flooding-Based Approach (2) </li></ul><ul><li>Problems with GnuStream: </li></ul><ul><li>Depending on the degree of connectivity among peers, the flooding of queries can generate a lot of network traffic. </li></ul><ul><li>Objects located out of the search scope (which the TTL determines) wouldn’t be found in the system. </li></ul>Computer Networking: A Top Down Approach, 4th edition. Jim Kurose, Keith Ross, Addison-Wesley, July 2007.
    19. 21. How to locate peers? <ul><li>DHT-Based Approach </li></ul><ul><ul><li>Each peer is assigned a peer ID by hashing its own IP address using a common known hash function such as SHA-1,17 </li></ul></ul><ul><ul><li>Each object is assigned a object ID in the same space of peer IDs by hashing the object itself. </li></ul></ul><ul><ul><li>The peer with an ID equal to the hashed object ID is responsible for storing the object’s location (or the actual object) </li></ul></ul>
    20. 22. DHT API: Get(), Remove(), Put() Eng Keong Lua et al., &quot;A survey and comparison of peer-to-peer overlay network schemes,&quot; Communications Surveys & Tutorials, IEEE , vol.7, no.2, pp. 72-93, 2005.
    21. 23. P2P-Chord Eng Keong Lua et al., &quot;A survey and comparison of peer-to-peer overlay network schemes,&quot; Communications Surveys & Tutorials, IEEE , vol.7, no.2, pp. 72-93, 2005.
    22. 24. How to locate peers? <ul><li>Comment on DHT-based search </li></ul><ul><ul><li>Pros: </li></ul></ul><ul><ul><ul><li>Use well-developed DHT protocols, which are scalable and offer good load balancing. </li></ul></ul></ul><ul><ul><ul><li>Famous protocols: Chord, Pastry, CAN </li></ul></ul></ul><ul><ul><li>Cons: </li></ul></ul><ul><ul><ul><li>DHT search do not consider the physical location or bandwidth of target peers </li></ul></ul></ul>
    23. 25. How to Construct Delivery Paths? <ul><li>Design Issues: </li></ul><ul><ul><li>Real-time delivery </li></ul></ul><ul><ul><ul><li>P2P relay incurs long delay </li></ul></ul></ul><ul><ul><li>Sufficient-bandwidth delivery </li></ul></ul><ul><ul><ul><li>Asymmetric upload/download bandwidth </li></ul></ul></ul><ul><ul><li>Failure recovery of peers </li></ul></ul><ul><ul><ul><li>Frequent peer join/leave </li></ul></ul></ul><ul><ul><li>Load imposed on network </li></ul></ul><ul><ul><ul><li>P2P relay incurs more traffic </li></ul></ul></ul>
    24. 26. How to Construct Delivery Paths? <ul><li>IP routing use physical network </li></ul><ul><ul><li>Physical topology </li></ul></ul><ul><ul><li>Neighbors are connected by routers/switches/hubs </li></ul></ul><ul><li>P2P routing use overlay network </li></ul><ul><ul><li>Logical topology is built on physical topology </li></ul></ul><ul><ul><li>Neighbors are connected by TCP/UDP connections </li></ul></ul>
    25. 27. Overlay Network is Not Efficient <ul><li>PLS (Physical Link Stress) </li></ul><ul><ul><li># of identical packets sent over a physical link </li></ul></ul><ul><li>RDP (Relative Delay Penalty) </li></ul><ul><ul><li>For two hosts, RDP = overlay delay/unicast delay </li></ul></ul><ul><li>Different P2P schemes have different PLS and RDP </li></ul>
    26. 28. PLS Example (1/3) Avg. PLS of IP Multicast = PLS(A-R1)+ PLS(R1-B)+ PLS(R1-R2)+ PLS(R2-C)+ PLS(R2-D) = (1+1+1+1+1)/5 = 1 Yang-hua Chu; Rao, S.G.; Seshan, S.; Hui Zhang, &quot;A case for end system multicast,&quot; Selected Areas in Communications, IEEE Journal on , vol.20, no.8, pp. 1456-1471, Oct 2002
    27. 29. PLS Example (2/3) Avg. PLS of IP Unicast = PLS(A-R1)+ PLS(R1-B)+ PLS(R1-R2)+ PLS(R2-C)+ PLS(R2-D) = (3+1+2+1+1)/5 = 1.6 (60% higher stress) Yang-hua Chu; Rao, S.G.; Seshan, S.; Hui Zhang, &quot;A case for end system multicast,&quot; Selected Areas in Communications, IEEE Journal on , vol.20, no.8, pp. 1456-1471, Oct 2002
    28. 30. PLS Example (3/3) Avg. PLS of P2P Overlay = PLS(A-R1)+ PLS(R1-B)+ PLS(R1-R2)+ PLS(R2-C)+ PLS(R2-D) = (2+1+1+2+1)/5 = 1.4 (40% higher) Yang-hua Chu; Rao, S.G.; Seshan, S.; Hui Zhang, &quot;A case for end system multicast,&quot; Selected Areas in Communications, IEEE Journal on , vol.20, no.8, pp. 1456-1471, Oct 2002
    29. 31. RDP Example RDP of P2P Overlay RDP(A-B) = 27/27 = 1 RDP(A-C) = 3/3 = 1 RDP(A-D) = 29/27 = 1.074 Yang-hua Chu; Rao, S.G.; Seshan, S.; Hui Zhang, &quot;A case for end system multicast,&quot; Selected Areas in Communications, IEEE Journal on , vol.20, no.8, pp. 1456-1471, Oct 2002
    30. 32. Topology of Overlay Network <ul><li>Single multicast tree </li></ul><ul><li>Multiple multicast tree </li></ul><ul><li>Mesh </li></ul>Yiu, W.-Pk.; Xing Jin; Chan, S.-H.G., “Challenges and Approaches in Large-Scale P2P Media Streaming”, IEEE Multimedia, Vol. 14, No.2, 2007.
    31. 33. Overlay Topology (1/3) <ul><li>Single Tree Topology </li></ul><ul><ul><li>Appraoch </li></ul></ul><ul><ul><ul><li>Each peer has fixed single parent </li></ul></ul></ul><ul><ul><li>Advantage </li></ul></ul><ul><ul><ul><li>Easy to optimize a single tree </li></ul></ul></ul><ul><ul><ul><ul><li>Example: delay + bandwidth </li></ul></ul></ul></ul><ul><ul><ul><li>Easy to implement </li></ul></ul></ul><ul><ul><li>Disadvantage </li></ul></ul><ul><ul><ul><li>Unbalanced load </li></ul></ul></ul><ul><ul><ul><ul><li>Few heavy-loaded interior nodes vs. many light-loaded leaf nodes </li></ul></ul></ul></ul><ul><ul><ul><li>Not robust </li></ul></ul></ul><ul><ul><ul><ul><li>Each peer connects to its only parent node via a single link </li></ul></ul></ul></ul><ul><ul><li>Example </li></ul></ul><ul><ul><ul><li>NICE, Zigzag, Overcast, … </li></ul></ul></ul>
    32. 34. Overlay Topology (2/3) <ul><li>Multiple Tree Topology </li></ul><ul><ul><li>Appraoch </li></ul></ul><ul><ul><ul><li>Each peer has fixed multiple parents </li></ul></ul></ul><ul><ul><li>Advantage </li></ul></ul><ul><ul><ul><li>More balanced load & more robust </li></ul></ul></ul><ul><ul><ul><ul><li>Multiple paths + layered video </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Multiple paths + MDC-based video </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Interior-node-disjoint trees: a node can be an interior node in at most one tree </li></ul></ul></ul></ul><ul><ul><li>Disadvantage </li></ul></ul><ul><ul><ul><li>Difficult to optimize multiple trees at the same time </li></ul></ul></ul><ul><ul><ul><li>Difficult to implement </li></ul></ul></ul><ul><ul><ul><ul><li>Synchronization between multiple parents </li></ul></ul></ul></ul><ul><ul><li>Example </li></ul></ul><ul><ul><ul><li>SplitStream, CoopNet, … </li></ul></ul></ul>
    33. 35. Overlay Topology (3/3) <ul><li>Mesh Topology </li></ul><ul><ul><li>Appraoch </li></ul></ul><ul><ul><ul><li>Each peer has dynamic multiple parents due to </li></ul></ul></ul><ul><ul><ul><li>(1) Unpredictable online/offline of peers </li></ul></ul></ul><ul><ul><ul><li>(2) Time-variable bandwidth and packet-loss rate of the Internet </li></ul></ul></ul><ul><ul><li>Advantage </li></ul></ul><ul><ul><ul><li>Most balanced load </li></ul></ul></ul><ul><ul><ul><li>Most robust </li></ul></ul></ul><ul><ul><li>Disadvantage </li></ul></ul><ul><ul><ul><li>Difficult to manage </li></ul></ul></ul><ul><ul><ul><ul><li>Synchronization between peers </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Real-time Internet behavior measurement </li></ul></ul></ul></ul><ul><ul><li>Example </li></ul></ul><ul><ul><ul><li>GnuStream, CoolStreaming, … </li></ul></ul></ul>
    34. 36. Outline <ul><li>Motivation </li></ul><ul><li>Introduction </li></ul><ul><li>On-Demand Streaming and Caching </li></ul><ul><li>Conclusions </li></ul>
    35. 37. Prominent P2P On-Demand Streaming Protocol <ul><li>P2Cast </li></ul><ul><ul><li>2003 , University of Massachusetts, USA </li></ul></ul><ul><li>P2VoD </li></ul><ul><ul><li>2004 , University of Central Florida, USA </li></ul></ul><ul><li>DCS </li></ul><ul><ul><li>2005 , Huazhong University of Science and Technology, China </li></ul></ul><ul><li>VMesh </li></ul><ul><ul><li>2007 , Hong Kong University of Science and Technology, China </li></ul></ul>
    36. 38. P2P VoD: P 2 Cast <ul><li>S ession </li></ul><ul><li>B ase tree </li></ul><ul><li>B ase stream </li></ul><ul><li>P atch stream </li></ul>Y. Guo, K. Suh, J. Kurose, D. Towsley, “P2Cast: P2P Patching Scheme for VoD Service,” in WWW 2003 . S napshot at time 40 T=10
    37. 39. P 2 Cast - New Client (X) Admission <ul><li>If new client X belongs to an already existing session (S) </li></ul><ul><ul><li>(1) X tries to join S’s base tree </li></ul></ul><ul><ul><li>(2) X tries select a patch server in S or the server </li></ul></ul><ul><ul><li>If (1) & (2) is successful, X is admitted </li></ul></ul><ul><ul><ul><li>Else, X will be rejected </li></ul></ul></ul><ul><li>Else, X starts a new session </li></ul><ul><ul><li>The server streams the entire video to X </li></ul></ul>
    38. 40. P 2 Cast - Base Tree Construction (1/2) <ul><li>Design principles </li></ul><ul><ul><li>B andwidth first principle </li></ul></ul><ul><ul><li>L ocal information only principle </li></ul></ul><ul><ul><ul><li>Information about this node itself, its parent node, and its child nodes </li></ul></ul></ul>
    39. 41. P 2 Cast - Base Tree Construction (2/2) <ul><li>1. New client X contacts a candidate parent P </li></ul><ul><ul><li>Default parent = server </li></ul></ul><ul><li>2. P estimates bandwidth B(P, X) </li></ul><ul><li>3. All children C i of P estimate bandwidth B(C i , X) </li></ul><ul><li>4. P identifies C max with largest B(C i ,X) </li></ul><ul><ul><li>If B(P, N) > B(C max , N) then </li></ul></ul><ul><ul><ul><li>P provides base/patch stream or one of them (patch stream has higher priority) </li></ul></ul></ul><ul><ul><ul><li>If P cannot fully fulfill, then redirect X to C max , starting from step 1. </li></ul></ul></ul><ul><ul><li>If B(P, N) <= B(C max , N) then </li></ul></ul><ul><ul><ul><li>X is re-directed to C max , starting from step 1 </li></ul></ul></ul>
    40. 42. P 2 Cast - Patch Server Selection <ul><li>The patch server selection process for a client X is identical to X’s base tree joining process </li></ul>Y. Guo, K. Suh, J. Kurose, D. Towsley, “P2Cast: P2P Patching Scheme for VoD Service,” in WWW 2003 .
    41. 43. P 2 Cast - Failure Recovery (1/2) <ul><li>Network Problem: </li></ul><ul><ul><li>If incoming traffic is low (base or patch stream) </li></ul></ul><ul><ul><ul><li>C lient A sends TEST_ERROR message to parent P </li></ul></ul></ul><ul><ul><li>t hen P responds A </li></ul></ul><ul><ul><ul><li>(1) No response </li></ul></ul></ul><ul><ul><ul><ul><li>A contacts the server and initiates the failure recovery process </li></ul></ul></ul></ul><ul><ul><ul><li>(2) Poor traffic condition </li></ul></ul></ul><ul><ul><ul><ul><li>A contacts the server and initiates the failure recovery process </li></ul></ul></ul></ul><ul><ul><ul><li>(3) WAIT </li></ul></ul></ul><ul><ul><ul><ul><li>P is still in its own recovery process </li></ul></ul></ul></ul><ul><ul><ul><ul><li>A sets up a timer </li></ul></ul></ul></ul>
    42. 44. P 2 Cast - Failure Recovery (2/2) <ul><li>Client Departure Problem </li></ul><ul><ul><li>Early leaving parent B sends DEPART_RECOVER message to all clients C i, i=1, 2, … </li></ul></ul><ul><ul><li>C i initiate the recovery process </li></ul></ul><ul><li>Failure recovery process </li></ul><ul><ul><li>Base stream recovery </li></ul></ul><ul><ul><ul><li>I dentical to a new client joining the base tree </li></ul></ul></ul><ul><ul><li>P atch stream recovery </li></ul></ul><ul><ul><ul><li>I dentical to path server selection process </li></ul></ul></ul>
    43. 45. P2P VoD – P2VoD Do, T.T.; Hua, K.A.; Tantaoui, M.A., &quot;P2VoD: providing fault tolerant video-on-demand streaming in peer-to-peer environment,&quot; Communications, 2004 IEEE International Conference on , vol.3, no., pp. 1467-1472 Vol.3, 20-24 June 2004 A video session (snapshot at time 36)
    44. 46. P2VoD vs. P2Cast <ul><li>Streaming and caching (CBR) </li></ul><ul><ul><li>P2VoD </li></ul></ul><ul><ul><ul><li>Cache the most recent content </li></ul></ul></ul><ul><ul><ul><li>A peer X can serve clients whose joining time is in the range of [ tj X , tj X +ab X ] </li></ul></ul></ul><ul><ul><ul><li>tj X : joining time of X </li></ul></ul></ul><ul><ul><ul><li>ab X : actual buffer size (display time) of X </li></ul></ul></ul><ul><ul><ul><li>Use one relay stream </li></ul></ul></ul><ul><ul><li>P2Cast </li></ul></ul><ul><ul><ul><li>Cache the initial part </li></ul></ul></ul><ul><ul><ul><li>Use two streams: base/patch streams </li></ul></ul></ul><ul><li>Failure Recovery </li></ul><ul><ul><li>P2VoD </li></ul></ul><ul><ul><ul><li>Handled locally, most of the times without involvement of the source </li></ul></ul></ul><ul><ul><li>P2Cast </li></ul></ul><ul><ul><ul><li>Get the source involved </li></ul></ul></ul><ul><ul><ul><li>Vulnerable to disruption due to server bottleneck </li></ul></ul></ul><ul><ul><ul><li>Resulting in long blocking time </li></ul></ul></ul>
    45. 47. P2VoD - Joining Algorithm (1/2) <ul><li>If all of the existing video sessions are closed </li></ul><ul><ul><li>A new video session is created, and new client X is the first member of G 1 of that video session </li></ul></ul><ul><li>Else, X will try to join existing video session </li></ul><ul><ul><li>1. X contacts a random member of the youngest generation G y , and acquires the list of peers at G y-1 </li></ul></ul><ul><ul><li>2. If the first block expiring time t Gy-1 exp > joining time of X, go to step 3; else go to step 4. </li></ul></ul><ul><ul><li>3. X becomes a member of G y </li></ul></ul><ul><ul><li>4. X is the first member of G y+1 of that video session </li></ul></ul>
    46. 48. P2VoD - Joining Algorithm (2/2) <ul><li>Introducing system parameter K </li></ul><ul><ul><li>To limit the maximum number of clients allowed in G 1 of each video session </li></ul></ul><ul><li>Parent selection: heuristic solutions </li></ul><ul><ul><li>Round Robin: the shortest serving time </li></ul></ul><ul><ul><li>Smallest Delay: bandwidth-enough, discover-first </li></ul></ul>
    47. 49. P2VoD – DCS (Distributed Cache Service) DSC is a DHT-Based P2P On-Demand Streaming Protocol Zuoning Yin; Hai Jin, &quot;DHT Based Collaborative Multimedia Streaming and Caching Service,&quot; TENCON 2005 2005 IEEE Region 10 , vol., no., pp.1-6, Nov. 2005
    48. 50. DCS - The Roles of Peers <ul><li>Rendezvous Peer ( RP ) </li></ul><ul><ul><li>Its id is closest to the hash result of the video’s name and the Unit ’s location in the video </li></ul></ul><ul><ul><li>Preserving the location information of all the segments of its corresponding Unit </li></ul></ul><ul><li>Root </li></ul><ul><ul><li>Id is closest to the hash result of the movie name </li></ul></ul><ul><ul><li>preserving the global information of the movie </li></ul></ul><ul><li>Ordinary Peers are peers neither RP nor Root </li></ul>
    49. 51. DHT Example: Pastry Routing Table Eng Keong Lua et al., &quot;A survey and comparison of peer-to-peer overlay network schemes,&quot; Communications Surveys & Tutorials, IEEE , vol.7, no.2, pp. 72-93, 2005.
    50. 52. Pastry Routing Table - Leaf Set Eng Keong Lua et al., &quot;A survey and comparison of peer-to-peer overlay network schemes,&quot; Communications Surveys & Tutorials, IEEE , vol.7, no.2, pp. 72-93, 2005.
    51. 53. Pastry Routing Table – Neighborhood Set Eng Keong Lua et al., &quot;A survey and comparison of peer-to-peer overlay network schemes,&quot; Communications Surveys & Tutorials, IEEE , vol.7, no.2, pp. 72-93, 2005.
    52. 54. Pastry - Routing Eng Keong Lua et al., &quot;A survey and comparison of peer-to-peer overlay network schemes,&quot; Communications Surveys & Tutorials, IEEE , vol.7, no.2, pp. 72-93, 2005.
    53. 55. Conclusion <ul><li>Future Research Issues for P2P Streaming </li></ul><ul><ul><li>Location-Aware DHT-Based Searching Algorithm </li></ul></ul><ul><ul><li>Wired/Wireless Hybrid P2P Streaming </li></ul></ul><ul><ul><li>Scalable Video Coding Based P2P Streaming </li></ul></ul>
    54. 56. Thank You! Q & A

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