1. UniversitatAutònoma de Barcelona Computer Architecture & Operating Systems Department P2P-VoD on Internet: Fault Tolerance and Control Architecture Rodrigo Godoi Advisor: Dr. Porfidio Hernández Budé Barcelona, July 2009.

2. Contents

3. Contents

5. Asynchronous requests

6. Every client enjoys entire content

9. Quality of Service (QoS)Control Architecture Fault Tolerance

11. Shared tree (e.g. PIM-SM)Application Layer Multicast ALM (e.g. NICE, ALMI) Overlay Multicast (e.g. OMNI)

12. Multicast- Patching Patching: multicast technique for multimedia data delivery Base stream t= 0 t = 6 Multicast Unicast Patchstream

14. Usage: file sharing, distributed multimedia systems, high performance computing.Synchronised usage of peers resources: Collaboration Groups

15. Tracker Peers Peers Peers Supernodes Peer-to-Peer - classification Peers Location mechanism

16. Peer-to-Peer - classification Overlay topology Chain Mesh Tree

18. Heterogeneous environment

19. Best-effort service

21. Network arranged by dimension and purpose (LAN, WAN, MAN)

22. Modeled by complex network theoryClustering coefficient Average path length

23. Problem Large scale system Failures Network Server Peers Frequent arrivals/departures

25. provide low start-up delay

26. have a clever buffer usage

27. enforce low control overheadControl Architecture Fault Tolerance

28. Control relevance P2P and Multicast Heterogeneity: Internet, peers capabilities, lifetimes Resources sharing Delivery Architecture Control Architecture

29. FaultTolerance Consequence of a failure System defect Do not solve the fault

30. State of the art

31. Contents

33. Flexibility

34. Reliability

35. Efficiency

36. Low overheadQoS

37. Contents

38. System architecture Clients overlay topology Distributed proxy servers Distributed video servers Internet Clients P2P Collaborations Servers overlaytopology IP Multicast zone Internet Autonomous System

40. Heartbeat messages

41. Centralised

44. Background: VoD service schemes Gather different aspects of P2P-VoD services

45. PCM/MCDB PCM MCDB PCM: Patch Collaboration Manager MCDB: Multicast Channel Distributed Branching Bypass

47. IP Multicast tree rearrangementDetection messages

49. Best-fit algorithm: Peer with great amount of available bandwidth is selected as parentVoD Server Session 4 Session 3 31.0 20.0 34.0 35.0 24.0 21.0 37.0 35.8 39.9 35.5 27.0 40.0 T

51. Subsequent recovery queriesDetection messages VoD Server Recovery messages Session 4 Session 3 31.0 20.0 34.0 35.0 24.0 21.0 37.0 35.8 39.9 35.5 27.0 40.0

52. Load cost Control messages PCM/MCDB P2Cast Heartbeats Heartbeats Detection IP multicast rearrangement Recovery request Subsequent queries Recovery Peers status Routers status Routers status Maintenance

53. Time cost Time consumption Recovery messages Detection Path (network theory): small-world effect latency PCM/MCDB Subsequent queries Recovery messages Detection Path (network theory): small-world effect latency P2Cast

54. Contents

56. Buffer sizebwo bwi buffer 8 9 10 11 12 L 6 7 13 Fault Tolerance Groups Buffer In Buffer Out

57. TheFaultToleranceScheme (FTS) MN C1 C2 Cushion Delivery Gen. purpose Altruist MN Fault Tolerance Groups MN MN L 1 2 3 1 2 3 t = 0 L 4 5 1 2 3 7 8 9 4 5 6 1 2 3 10 7 MN 13 14 L 15 10 11 12 8 9 4 5 1 2 3 t = 0 t = 0 C1 7 L 4 5 6 1 2 3 6 7 C1 10 11 L 12 7 8 9 4 5 6 9 10 6 7 8 13 14 Video 8 9 10 6 7 13 14 15 11 12 3 4 5 1 2 Manager Node MN C2 7 L 4 5 6 1 2 3 14 15 11 12 13 t = 3 t = 3 t = 10 C1 Video 8 9 10 6 7 13 14 15 11 12 3 4 5 1 2 7 Video 8 9 10 6 13 14 15 11 12 3 4 5 1 2 FTS Collaborators [t = 17]

59. removes subsequent queries during recovery

60. eliminates messages for peers status maintenance

63. More than 50 classes in C++

64. Over 46.000 lines

65. Peer arrival rate: Poisson

67. Peers disruptions: Weibull

68. FMP instrumentation: Load and Time costs measurement Fault probability Lifetime

69. Contents

70. Experimental Results

71. Failure Management Process validation

72. Control vs. Multimedia traffic Analytical results (PCM/MCDB and P2Cast) ∆w = 13%-39% ∆w =13%- 37% ∆w = 10%-28% Simulated results (P2Cast)

73. Load cost analysis

74. Load cost analysis

75. Time cost analysis High latency Time cost increment Recovery control messages

76. Time cost analysis Download rate: 1500 kb/s (750+750) Cushion buffer 56MB 11MB 1 min. 5 min. Start-up delay

77. Experimental Results

78. Load cost analysis Cost increment Cost reduction FTS I - heartbeat detection FTS II - buffer monitoring detection

82. FlexibilityAltruist buffer 338MB Altruist buffer 102MB

83. Contents

84. Conclusions Control mechanism plays a crucial role on designing P2P-VoD systems Load cost Control overhead: network congestion, bandwidth resources Time cost Efficiency: buffer usage, start-up delay Load and Time costs trade-off Reduction of Load and Time costs Quality of Service

86. presents hierarchical control structure

87. has scalable backup mechanism

88. do not demand extra data communication and dedicated resources

89. is able to guarantee system reliability

92. Implementation of the FTS in a simulation environment

93. FTS improvement: storing parts of non-visualized contents; using non-volatile storage devices (e.g. Solid State Disk drives)

94. Addition of VCR / DVD-like operations

97. Peer: multimedia client / source

98. FTG member: collaborator in the FTS

99. Distributed backup: flexibility and reliability.

100. Built on the fly: backup do not need retransmission.

101. P2P based: mechanism uses own system available resources.

102. Hierarchical control: scalability and deployment.

104. The FTS formationlaw While MN C1 C2 C3 A · 2 A · 3 A · 5 A · 5 15 15 15 15 If then Add Collaborator to FTG. If if: Peers’ bandwidth lower than playback rate (bw<Vpr) then New FTG. if: A Video C B D E H G F … Collaboration Capacity A Buffer and Bandwidth constraints … C1 A* B* … A* B* C2 FTG size MN [500kb/s] C1 [200kb/s] C2 [300kb/s] C3 [500kb/s] Vpr [1500kb/s] … A* B* C3 MN A* … B*

105. TheFaultToleranceScheme (FTS) MN C1 C2 Client MN I II III IV Creation of Fault Tolerance Groups Local Server Collab. availability FTS ack. Join to FTG Start new FTG and become Manager Node Standby status

106. TheFaultToleranceScheme (FTS) Standby Peer I II FTG: complexity and maintenance O(NCFTG) MN MN failure Local Server Member failure C1 C1 C2 Designation of new MN Restoring the FTG Restoring the FTG

111. Conclusions - publications