5. Ongoing Work

1
Nazanin Magharei, Amir H. Rasti, Daniel
Stutzbach, Reza Rejaie University of Oregon
1. Introduction
2. Existing Approaches

• Extended the idea of application level
  multicast
• Peers are organized into one (or multiple)
  tree(s)
• Static mapping of content to tree(s)
• Complex overlay const, Simple content delivery
• Limitation Unable to maximize delivered quality
  to individual peers
• Resulting in bandwidth or content bottlenecks and
  thus achieves limited rate of content diffusion.
• File swarming (e.g. BitTorrent) achieves higher
  diffusion rate but cannot support streaming.

• Problem Scalable one-to-many video streaming
  over P2P overlays, e.g. Internet video
  broadcasting.
• Design goals
• Session-level minimizing associated network load
• Peer-level maximizing delivered quality to
  peers.
• Components Overlay Const., Content Delivery
• Challenges
• Heterogeneity and asymmetry of access link BW.
• Dynamics of peer participations, i.e. churn.
• Dynamics of bandwidth variations and sharing.

3. PRIME

• Content Delivery Each peer dynamically
  coordinates content delivery from all of its
  parents
• Parents report their available content to
  children
• Each peer periodically requests required packets
  from individual parents.
• Swarming Peers maintain a close playout time to
  swarm a recent window of available packets.
• Design Issues
• 1) Stability of Delivered Quality by in-time
  delivery of required packets.
• 2) Feasibility of Swarming by diversifying
  available packets among peers.
• 3) Rapid Diffusion of New Packets by requesting a
  sufficient portion of new packets.

• Design Philosophy Simple overlay construction,
  independent dynamic content delivery by each
  peer
• Overlay Construction Peers form a high degree,
  randomly connected, and directed mesh.
• Advantages
• 1) Overlay construction maintenance is simple.
• 2) Accommodates BW heterogeneity asymmetry.
• 3) Improves path diversity among connections.
• 4) Leads to biased connectivity, each peer is
  more likely to connect to peers with higher
  uptime.
• Long-lived peers observe less churn.
• Assumptions
• Streaming content is Multiple Description
  encoded.
• All connections are congestion controlled.

Multiple-tree approach with static mapping of
layers to trees
PRIME
4.Preliminary Results

• Peers can effectively utilize their access link
  bandwidth with a proper number of parents (Fig 1)
• PRIME can maximize delivered quality to
  heterogeneous peers if swarming window is
  sufficiently large (Fig 2)

Fig 2
Fig 1
5. Ongoing Work

• Eliminating the need for content reporting.
• Incorporating an incentive mechanism.
• For more info, visit our project web site at
  http//mirage.cs.uoregon.edu/PRIME

• Investigating the impact of per-peer behavior on
  the global pattern of content diffusion.
• Examining the effects of overlay properties,
  dynamics, BW heterogeneity encoding on content
  delivery.

ACM SIGCOMM, Philadelphia, August 2005