Issues in Offering Live P2P Streaming Service to Residential Users Nazanin Magharei, *Yang Guo, and Reza Rejaie Dept. of Computer and Information Science *Princeton CR Lab University of Oregon Thomson Inc.

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Issues in Offering Live P2P Streaming Service to
Residential UsersNazanin Magharei, Yang Guo,
and Reza Rejaie Dept. of Computer and
Information Science Princeton CR Lab
University of Oregon Thomson
Inc.
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Outline

• Introduction and related work
• PRIME Mesh-based P2P streaming service
• Issues in offering p2p streaming to residential
  users
• Effect of available resource
• Effect of heterogeneous bandwidth
• Effect of freeloaders
• Effect of number of users
• Conclusions and summary

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Introduction

• P2P technique attracting attentions from
  commercial world
• NBC Universal goes peer-to-peer wurldmedia.com
• BitTorrent raised 8.75 million venture capitals
• Teamed with CacheLogic to work for BT
• Startups providing P2P live program pplive,
  coolstreaming
• BBC IMP
• Why?
• Reduce the cost to compete with piracy
• Conceivably provide p2p live streaming in a
  commercial setting
• Using mesh-based p2p streaming

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Introduction

• P2P live streaming
• Tree-based approach
• ESM, SplitStream, etc.
• Mesh-based approach
• Coolstreaming, Chainsaw, PRIME, etc.
• Fundamental difference static mapping of
  content to delivery topology vs. dynamic mapping

Pkt delivery time Bandwidth variation Peer degree Group size Persistent churn Batch departure
Mesh
Tree
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Introduction and Related Work

• Challenges
• Heterogeneous access speed DSL, cable modem,
• Insufficient resource
• Asymmetric bandwidth uplink bandwidth lt
  downlink bandwidth
• Free-loaders
• Not willing to contribute
• Cannot contribute
• Behind NAT box or firewall
• Key questions
• What is the impact of available resource to
  overall performance?
• How similar (different) is such an effect across
  peers with different bandwidth?
• Whether and how the freeloaders affect the
  overall performance and individual received
  quality?

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PRIME Mesh-based P2P Streaming Service

• Peer expects to receive maximum deliverable
  quality through its access link
• Using MDC in content delivery
• Two possible performance bottlenecks
• Bandwidth bottleneck
• Insufficient aggregate bandwidth from all parents
• Content bottleneck
• Insufficient useful content from all parents
• PRIME attempts to minimize these bottlenecks

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Global Pattern of Content Delivery
Source

• Connections in the overlay have roughly the same
  bandwidth
• Group peers into levels, based on their shortest
  distance from source
• Each peer with degree d in level n has at least
  one parent in level n-1 (diffusion parent) and
  d-1 parents in the same or lower levels (swarming
  parents)

Level 1
1
3
2
Level 2
depth
6
4
7
5
10
12
13
8
9
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Level 3
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Global Pattern of Content Delivery

• Diffusion phase
• Peers should receive a data unit as fast as
  possible
• Swarming phase
• Peers exchange (swarm) data units with each other
  until receive their desired quality of the
  segment

SRC
Level 1
1
3
2
6
4
Level 2
7
5
10
Level 3
12
13
8
9
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Simulation Setting

• Evaluated using ns with congestion control
• Network topology generated using Brite
• Video rate of 400 kbps, downlink bandwidth of 550
  kbps
• Various resource distribution

Uplin Bw SC1 SC2 SC3 SC4 SC5 SC6
128kpbs 27 54 13 5 11 50
384kpbs 60 20 80 9 14 39
1Mbps 13 26 7 36 25 11
0kbps 0 0 0 50 50 0
RI 1 1 1 1 0.8 0.8
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Effect of Available Resource
Avg. received quality
Resource Index
CDF of received quality
Average received quality is proportional to the
resource index, however the individual received
quality is random
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Effect of Heterogeneous Bandwidth
Avg. received quality
CDF of received quality
Upload bandwidth

• Bandwidth heterogeneity has no impact on the
  peers received quality
• No correlation between received quality and
  resource contribution

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Effect of Free-loaders
Free-loaders degrade the connectivity between
different diffusion trees, hence prevent content
swarming and limit delivery quality
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Effect of Number of Users
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Summary

• Two issues identified
• In resource poor scenarios, the delivered quality
  to peers is not correlated to their contribution
• P2P streaming can handle heterogeneous bandwidth,
  however the presence of free-loaders
  significantly affect the mesh connectivity and
  degrade delivered quality
• Solution contribution-aware p2p streaming
• Delivered quality is proportional to contribution
• Encourage cooperation

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Backup Slides
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Global Pattern of Content Delivery
SRC
Level 1
1
3
2
6
4
Level 2
7
5
10
Level 3
12
13
8
9
11
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PRIME Mesh-based P2P Streaming Service

• Prior studies often assume a fix peer degree
• Bandwidth bottleneck only depends on overlay
  topology
• Incoming/outgoing bandwidth of participating
  peers
• Incoming/outgoing degree of participating peers
• Avg. BW for a connection between parent p and
  child c
• MIN (outbwp/outdegp, inbwc/indegc)
• All connections in the overlay have roughly the
  same bandwidth