Feb. 22, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 11

A Hybrid Video Streaming Scheme A Hybrid Video Streaming Scheme on Hierarchical P2P Networkson Hierarchical P2P Networks

＊＊ Shinsuke SuetsuguShinsuke SuetsuguNaoki Wakamiya, Masayuki MurataNaoki Wakamiya, Masayuki Murata

Osaka University, JapanOsaka University, Japan

Koichi Konishi, Kunihiro TaniguchiKoichi Konishi, Kunihiro TaniguchiNEC Corporation, JapanNEC Corporation, Japan

Feb. 22, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 22

OverviewOverview

Research backgroundResearch background ObjectiveObjective Proposed schemeProposed scheme

• Scheduling algorithmScheduling algorithm• Tree construction mechanismTree construction mechanism• Fault recovery mechanismFault recovery mechanism

Simulation experimentsSimulation experiments Conclusion & future workConclusion & future work

Feb. 22, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 33

Research Background (1/2)Research Background (1/2)

Increased popularity of video streamingIncreased 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 technologyDevelopment of P2P technology• distribute video streaming with P2P multicastdistribute video streaming with P2P multicast• reduce load of serversreduce load of servers

Server

Client Peer

Server

P2P multicast

constructdistribution

tree

Client-server model

Feb. 22, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 44

Research Background (2/2)Research Background (2/2)

How to construct “good” distribution How to construct “good” distribution trees?trees?• one way is to measure characteristics of one way is to measure characteristics of

physical networks, such as delay or bandwidthphysical networks, such as delay or bandwidth requires long time requires long time causes heavy loadcauses heavy load

• enterprises or universities: well-organized enterprises or universities: well-organized networks are constructednetworks are constructed

branch networks or division networksbranch networks or division networks no need to measure characteristicsno need to measure characteristics construct distribution trees easily and quicklyconstruct distribution trees easily and quickly

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ObjectiveObjective

We propose a hybrid video streaming scheme We propose a hybrid video streaming scheme for…for…• networks hierarchically constructed based on networks hierarchically constructed based on

organization structure organization structure • networks with thousands or ten thousands of usersnetworks with thousands or ten thousands of users

Objective of our proposalObjective of our proposal• reduce load of serversreduce load of servers• reduce load of networksreduce load of networks

avoid connecting between long-distance peersavoid connecting between long-distance peers avoid using a link repeatedly for a flowavoid 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

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Overview of Proposed SchemeOverview of Proposed Scheme

Tree Server(GTS)

Video Server(ORG)

SchedulingServer(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

branch

branch

division

division

division

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Outline of Proposed SchemeOutline of Proposed Scheme

１．１． Scheduling algorithmScheduling algorithm• use “pyramid broadcasting”use “pyramid broadcasting”

→→ reduce initial waiting time until video starts playingreduce initial waiting time until video starts playing

２．２． Tree construction mechanismTree construction mechanism• construct P2P multicast treesconstruct P2P multicast trees

→→ reduce load of serversreduce load of servers• make networks hierarchical based on physical structuremake networks hierarchical based on physical structure

→→ reduce load of networksreduce load of networks

３．３． Fault recovery mechanismFault recovery mechanism• recover from faults rapidly with only local recover from faults rapidly with only local

communicationcommunication→→ reduce freeze time caused by faultreduce freeze time caused by fault

Feb. 22, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 88

１．１． Scheduling AlgorithmScheduling Algorithm- pyramid broadcasting -- 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

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２．２． Tree Construction MechanismTree Construction Mechanism

trees are constructed trees are constructed

segment-by-segment and slot-by-slotsegment-by-segment and slot-by-slot

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２．２． Tree Construction MechanismTree Construction Mechanism- inter-branch tree -- 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

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２．２． Tree Construction MechanismTree Construction Mechanism - inter-branch tree -- inter-branch tree -

Tree Server（ GTS ）

Video Server（ ORG ）

branch A

branch C

branch B

limitation for number of childrenfanout = 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, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 1212

２．２． Tree Construction MechanismTree Construction Mechanism - inter-subnet tree -- 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, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 1313

２． ２． Tree Construction MechanismTree Construction Mechanism - inter-NP (Normal Peer) tree -- inter-NP (Normal Peer) tree -

difference between 1st and later segmentsdifference 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

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３．３． Fault Recovery MechanismFault Recovery Mechanism- recovery within subtree -- recovery within subtree -

Fault:Fault:• peer leaves networkpeer leaves network

variety of reasonsvariety of reasons different occasionsdifferent occasions

ＲＲ ecovery within subtreeecovery within subtree• each peer has information each peer has information

about ancestorsabout ancestors• mechanism can be applied mechanism can be applied

in the same manner to:in the same manner to: inter-branch treesinter-branch trees inter-subnet treesinter-subnet trees inter-NP treesinter-NP trees

connectionrequest

consider fanout

limitation

recoveryconnection request

Inform address

connection request

Feb. 22, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 1515

Simulation ExperimentsSimulation Experiments Evaluation criteriaEvaluation criteria

• load of servers and peers load of servers and peers • initial waiting timeinitial waiting time• recovery and freeze timerecovery and freeze time

ScenarioScenario• 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: 2,790average 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: 0.004 fault probability: 0.004

(= 47% for correctly receiving the whole video)(= 47% for correctly receiving the whole video)• video duration: 186 [sec]video duration: 186 [sec]• number (lengths) of segments: 5 number (lengths) of segments: 5 （（ 6, 12, 24, 48, 96 [se6, 12, 24, 48, 96 [se

c]c] ））

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Initial Waiting TimeInitial Waiting Time

average waiting time: 2.94 secaverage waiting time: 2.94 sec

maximum waiting time: < 6 secmaximum waiting time: < 6 sec

initial waiting time [sec]

cum

ula

tive

pro

babili

ty

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Freeze TimeFreeze Time

video freezes for only 0.5 % video freezes for only 0.5 %

of all thousands of of all thousands of peerspeers

maximum freeze time: < 1 secmaximum freeze time: < 1 sec

freeze time [sec]

cum

ula

tive

pro

babili

ty

Feb. 22, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 1818

Conclusion & Future WorkConclusion & Future Work

Proposal of video streaming distribution Proposal of video streaming distribution schemescheme

Scheduling algorithmScheduling algorithm Tree construction mechanismTree construction mechanism Fault recovery mechanismFault recovery mechanism

• Reduction of initial waiting time and freeze Reduction of initial waiting time and freeze timetime

ExtensionsExtensions• Further reduction of load on the tree serverFurther reduction of load on the tree server• Optimization of tree structures to eliminate Optimization of tree structures to eliminate

long-distance redundant linkslong-distance redundant links

Feb. 22, 2005Feb. 22, 2005 EuroIMSA 2005EuroIMSA 2005 1919

Thank you.Thank you.