Feb. 22, 2005 EuroIMSA A Hybrid Video Streaming Scheme on Hierarchical P2P Networks ＊ Shinsuke Suetsugu Naoki Wakamiya, Masayuki Murata Osaka University, Japan Koichi Konishi, Kunihiro Taniguchi NEC Corporation, Japan

Feb. 22, 2005 EuroIMSA Overview Research background Research background Objective Objective Proposed scheme Proposed scheme Scheduling algorithmScheduling algorithm Tree construction mechanismTree construction mechanism Fault recovery mechanismFault recovery mechanism Simulation experiments Simulation experiments Conclusion & future work Conclusion & future work

Feb. 22, 2005 EuroIMSA Research Background (1/2) Increased popularity of video streaming Increased popularity of video streaming streaming: to decode while downloadingstreaming: to decode while downloading distribution of movies or newsdistribution of movies or news Development of P2P technology Development of P2P technology distribute video streaming with P2P multicastdistribute video streaming with P2P multicast reduce load of serversreduce load of servers Server ClientPeer Server P2P multicast construct distribution tree Client-server model

Feb. 22, 2005 EuroIMSA Research Background (2/2) How to construct “ good ” distribution trees? How to construct “ good ” distribution trees? one way is to measure characteristics of physical networks, such as delay or bandwidthone way is to measure characteristics of physical networks, such as delay or bandwidth requires long time requires long time causes heavy load causes heavy load enterprises or universities: well-organized networks are constructedenterprises or universities: well-organized networks are constructed branch networks or division networks branch networks or division networks no need to measure characteristics no need to measure characteristics construct distribution trees easily and quickly construct distribution trees easily and quickly

Feb. 22, 2005 EuroIMSA Objective We propose a hybrid video streaming scheme for … We propose a hybrid video streaming scheme for … networks hierarchically constructed based on organization structurenetworks hierarchically constructed based on organization structure networks with thousands or ten thousands of usersnetworks with thousands or ten thousands of users Objective of our proposal Objective of our proposal reduce load of serversreduce load of servers reduce load of networksreduce load of networks avoid connecting between long-distance peers avoid connecting between long-distance peers avoid using a link repeatedly for a flow avoid using a link repeatedly for a flow reduce initial waiting time until video starts playingreduce initial waiting time until video starts playing reduce freeze time caused by faultsreduce freeze time caused by faults

Feb. 22, 2005 EuroIMSA Overview of Proposed Scheme Tree Server (GTS) Video Server (ORG) Scheduling Server (SS) Local Tree Server (LTS) Subnet Tree Server (STS) Normal Peer （ NP ） branch A branch C branch B subnet a subnet c subnet b Central office branch division

Feb. 22, 2005 EuroIMSA Outline of Proposed Scheme １． Scheduling algorithm use “ pyramid broadcasting ” → reduce initial waiting time until video starts playinguse “ pyramid broadcasting ” → reduce initial waiting time until video starts playing ２． Tree construction mechanism construct P2P multicast trees → reduce load of serversconstruct P2P multicast trees → reduce load of servers make networks hierarchical based on physical structure → reduce load of networksmake networks hierarchical based on physical structure → reduce load of networks ３． Fault recovery mechanism recover from faults rapidly with only local communication → reduce freeze time caused by faultrecover from faults rapidly with only local communication → reduce freeze time caused by fault

Feb. 22, 2005 EuroIMSA １． Scheduling Algorithm - pyramid broadcasting - ｔ ｔ playout → video data Scheduling Server （ SS ） Video Server （ ORG ） play-rate b transmission – rate 2b distribute continuously on different channels among each segments segment slot peer １ ： ２ ： ４

Feb. 22, 2005 EuroIMSA ２． Tree Construction Mechanism trees are constructed segment-by-segment and slot-by-slot

Feb. 22, 2005 EuroIMSA ２． Tree Construction Mechanism - inter-branch tree - Tree Server （ GTS ） Video Server （ ORG ） LTS inform IP address of Video Server LTS participation request The first participation request in this branch branch A branch C branch B Central office

Feb. 22, 2005 EuroIMSA ２． Tree Construction Mechanism - inter-branch tree - Tree Server （ GTS ） Video Server （ ORG ） branch A branch C branch B limitation for number of children fanout = 2 list of ancestors: video server → LTS B recursively attempts to connect to children on failure inform IP address of one of its children Peers store informed addresses as a list of ancestors Central office

Feb. 22, 2005 EuroIMSA ２． Tree Construction Mechanism - inter-subnet tree - LTS STS Tree Server （ GTS ） Video Server （ ORG ） consider its fanout branch A subnet A subnet D subnet B subnet C inform IP address of LTS in this branch

Feb. 22, 2005 EuroIMSA ２． Tree Construction Mechanism - inter-NP (Normal Peer) tree - difference between 1st and later segments difference between 1st and later segments NP inform IP address of STS in this subnet 1st segment STS later segment access STS of previous segment directly without Tree Server Tree Server （ GTS ） consider its fanout subnet A

Feb. 22, 2005 EuroIMSA ３． Fault Recovery Mechanism - recovery within subtree - Fault: Fault: peer leaves networkpeer leaves network variety of reasons variety of reasons different occasions different occasions Ｒ ecovery within subtree Ｒ ecovery within subtree each peer has information about ancestorseach peer has information about ancestors mechanism can be applied in the same manner to:mechanism can be applied in the same manner to: inter-branch trees inter-branch trees inter-subnet trees inter-subnet trees inter-NP trees inter-NP trees connection request consider fanout limitation recovery connection request Inform address connection request

Feb. 22, 2005 EuroIMSA Simulation Experiments Evaluation criteria Evaluation criteria load of servers and peersload of servers and peers initial waiting timeinitial waiting time recovery and freeze timerecovery and freeze time Scenario Scenario 5 branches and 5 subnets in a branch5 branches and 5 subnets in a branch peer arrival process: uniform, average: 30 [arrivals/sec]peer arrival process: uniform, average: 30 [arrivals/sec] → average total number of peers: 2,790 transmission delay between server and peer: 200 [ms]transmission delay between server and peer: 200 [ms] transmission delay between peers: 20 [ms]transmission delay between peers: 20 [ms] fanout degree: 3fanout degree: 3 fault probability: 0.004fault probability: (= 47% for correctly receiving the whole video) video duration: 186 [sec]video duration: 186 [sec] number (lengths) of segments: 5 （ 6, 12, 24, 48, 96 [sec] ）number (lengths) of segments: 5 （ 6, 12, 24, 48, 96 [sec] ）

Feb. 22, 2005 EuroIMSA Initial Waiting Time average waiting time: 2.94 sec maximum waiting time: < 6 sec initial waiting time [sec] cumulative probability

Feb. 22, 2005 EuroIMSA Freeze Time video freezes for only 0.5 % of all thousands of peers maximum freeze time: < 1 sec freeze time [sec] cumulative probability

Feb. 22, 2005 EuroIMSA Conclusion & Future Work Proposal of video streaming distribution scheme Proposal of video streaming distribution scheme Scheduling algorithm Scheduling algorithm Tree construction mechanism Tree construction mechanism Fault recovery mechanism Fault recovery mechanism Reduction of initial waiting time and freeze timeReduction of initial waiting time and freeze time Extensions Extensions Further reduction of load on the tree serverFurther reduction of load on the tree server Optimization of tree structures to eliminate long-distance redundant linksOptimization of tree structures to eliminate long-distance redundant links

Feb. 22, 2005 EuroIMSA Thank you. Thank you.