Transcript CoolStreaming - Network and System Laboratory

CoolStreaming/DONet: A Data-driven
Overlay Network for Peer-to-Peer
Live Media Streaming
Authors: Xinyan Zhang., Jiangchuan Liu, Bo
Li,
and Tak-Shing Peter Yum.
Presenter: Elaine
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Outline
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Introduction
Related Work
Design and Optimization of Donet
Planet-Based Performance Evaluation
CoolStreaming
Conclusion and Future works
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Multimedia applications
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IP multicast is the best way
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Live media streaming from a source to a large
population of users.
NetTV, news broadcast
The lack of incentives to install multicast routers
Political and practical issues
Application-level solution: Overlay network
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Built on the unicast tunnels across cooperative
participating users.
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Features of overlay network with streaming application.
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Easily crash/leave
Streaming application
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Many overlay construction algorithms advocate a tree
structure for data delivering.
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High bandwidth
Continuity
highly vulnerable.
Restriction of the flow directions
Proposed data-centric overlay network
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No predetermined roles
Self-organization
Data availability guides the flow directions.
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Outline
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Introduction
Related Work
Design and Optimization of Donet
Planet-Based Performance Evaluation
CoolStreaming
Conclusion and Future works
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A brief overview of the existing overlay
streaming protocols in the pure p2p paradigm
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Tree-based protocol
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An internal node with high load leaving or crashing
often causes underflow in a large population of
descendants.
Unbalanced load
Repairing mechanisms are complex.
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Gossip-based protocol
 A node sends a newly generated message to a
set of randomly selected nodes, iteratively.
 Cause redundancy especially for media
streaming application.
 Partially used for membership management
and data delivery in Donet
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Outline
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Introduction
Related Work
Design and Optimization of Donet
Planet-Based Performance Evaluation
CoolStreaming
Conclusion and Future works
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Three key modules
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Membership manager
Partnership manager
Scheduler
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Interaction of modules
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Node join and Membership Management
Each Donet node has a unique id and Mcache.
 How to create and update the mcache.
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Each node periodically generates a membership message
to announce its existence
SCAM(Gossip) to distribute the mcache messages..
Message format: <seq num, id,num partner, time to
live>
Entry Message format: <seq num, id,num partner,
time to live,last_update_time>
Node join algorithm
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B.
Buffer Map Representation and Exchange
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A video stream is divided into segments of uniform
length
Buffer Map: represent the availability of the segments
Continuously exchange BM with partners, and
schedules which segment is to be fetched from which
partner accordingly.
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D.
Failure Recovery and Partnership Refinement
Failure Recovery
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Graceful departure
Node failure
Partnership Refinement
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Periodically establish new partnerships with nodes randomly
selected from its mCache.
Node i use function max{¯si,j , ¯sj,i} to score its partners
¯si,j: the average number of segments that node i
retrieved
from node j per unit time.
¯sj,i: the average number of segments that node j
retrieved
from node j per unit time.
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Outline
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Introduction
Related Work
Design and Optimization of Donet
Planet-Based Performance Evaluation
CoolStreaming
Conclusion and Future works
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A.
Design of the Experiment System
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Almost all active nodes over PlanetLab,200~300
Experiment May to June, 2004
Each active PlanetLab node runs a copy of the prototyped
program,acting a s a DONet node.
Origin node: Located in the United States
Monitoring node: In Hong Kong
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B.
Performance under Stable Environment
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All nodes persist in the lifetime of the streaming(120min)
Control overhead(left)
Scalability(left)
Playback continuity(right).
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C.
Performance under Dynamic Environment
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Dynamic node joining , leaving, and failure.
Following the ON/OFF model.
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D.
Comparison with the Tree-based Overlay
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Metrics: End-to-End delay / Continuity
The number of partners is set to 4 in Donet.
The degree of each tree node is limited to 3,
except root(4).
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Different capacity and bandwidth cause some
children move to lower levels.
Fig 11/fig12/fig 13
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A full and balanced 3-ary tree of 231 nodes
has a height of 5 only.
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Summary and Caveats
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Performance of Donet is acceptable
Overhead is low(1% of the video traffic)
Scalability
Compared to tree-based overly
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Continuity is much better under highly dynamic environment.
End-to-end delay is comparable.
Caveats
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Scalability
Representability
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Outline
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Introduction
Related Work
Design and Optimization of Donet
Planet-Based Performance Evaluation
CoolStreaming
Conclusion and Future works
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A public Internet based DONet package, called
CoolStreaming.
Released the first version (v.0.9) on May 30, 2004.
CoolStreaming v.0.9
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Two interesting facts:
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The current Internet has enough available
bandwidth to support TV-quality
streaming(>=450 Kbps)
The larger the data-driven overlay is, the
better the streaming quality it delivers.
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Conclusion
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Proposed DONet
Simple overlay structure (according to the data
availability)
Scalable membership and partnership management
algorithm
Good playback quality under formidable network
condition
Compared to tree-based overlay,it achieves much more
continuous streaming with comparable delay.
Released CoolStreaming v.0.9
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