Transcript BEAM: Alliance Based Peering

An Alliance based Peering
Scheme for P2P Live Media
Streaming
Darshan Purandare
Ratan Guha
University of Central Florida
August 31, 2007 @ P2P-TV, Kyoto
Outline
Chunk based P2P models
Current Issues
Proposed peering scheme
Discussion and summary
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Chunk based P2P models
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1
…
Server
3
2
…
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…
5
…
4
…
…
 Stream is split into pieces
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Working Philosophy
Peers exchange buffer map of data availability
Retrieve the missing pieces and upload pieces to
neighbors
Scheduling algorithm finds which pieces to
retrieve and from whom
Partnership refinement helps to obtain better
peers in terms of uploading rate
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Outline
Chunk based P2P models
Current Issues
Proposed peering scheme
Discussion and summary
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Current Issues
Quality of Service can improve [Hei et al. 06]
Long start up time
Peer Lag
Unfairness [Ali et al. 06]
Uplink bandwidth distribution uneven
Sub-optimal uplink utilization
May affect QoS & Scalability
Can we do better ?
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Outline
Chunk based P2P models
Current Issues
Proposed peering scheme
Discussion and summary
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Proposed Model
Chunk based paradigm but overlay formation
using alliances
Nodes cluster in groups of 4-8 to form alliances
Media server relays content to Power nodes
BEAM: Bit strEAMing
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BEAM: Working Philosophy
A new node upon arrival obtains peerlist from Tracker
Peerlist contains nodes in similar bandwidth range and
similar network (if possible)
Contacts peers for stream content
Starts joining alliances or creates one
Server relays stream content to Power nodes
Power nodes changes periodically based on Utility Factor
(UF)
A node’s UF computed using:

Cumulative share ratio (CSR)

Temporal share ratio (TSR)
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Alliance Formation
Peerlist of Node 1:: 6, 17, 23
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Peerlist of Node 6: 12, 22, 43
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Alliance Properties
A node can be a member of multiple alliances
H: Maximum number of nodes in an Alliance
K: Maximum number of alliances a node can
join
Number of neighbors = K(H-1)
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Alliance Functionality
H=5
K=2
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Alliance Functionality
H=5
K=2
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Why form Alliances ?
Clustering into alliances forms a small world
network graph
Short Path Length
Robust to network perturbations such as churn
Close knit group ensures streaming content is
readily available within alliances
Alliance members have common trust & treaty
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Small World Network
Dense local clustering
(high clustering
coefficient)
Some links to other part
of the graph (non local)
Overlay distance is
near-optimal
Robust to churn
[Watts et al., Nature,98]
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Simulator Details
Streaming rate = 512 Kbps
Media Server’s Uplink = 1536 Kbps (3 links)
Heterogeneous bandwidth class
(512,128), (768,256), (1024, 512),
(1536,768), (2048, 1024)
H, K = 4, 2 (6 neighbor nodes)
Each node buffers content for 120 sec
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QoS: Average Jitter Rate
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QoS: Average Latency
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Uplink Utilization
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Fairness: Share Ratio Range
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Fairness: Jitter Factor Range
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Fairness: Latency Range
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Summary
Alliance based peering scheme is an effective
technique to group peers
QoS, Uplink throughput and fairness results are
at par or even better than CoolStreaming
Peer lag can be improved using BEAM
Initial buffering time can be slightly improved
Our research is complementary to advance
source and channel coding techniques.
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Questions or Comments
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Thank You!