Peer-to-Peer Content Sharing

P2P File Sharing Benefits Why use a P2P model for a file sharing application?

Research Areas Peer discovery and group management Data placement and searching Reliable and efficient file exchange Security/privacy/anonymity/trust

Design Concerns Group Management –Per-node state –Load balancing –Fault tolerance/resiliency Search –Bandwidth usage –Time to locate item –Success rate –Fault tolerance/resiliency

Approaches Centralized Unstructured Structured (Distributed Hash Tables)

Centralized Napster model Benefits: Drawbacks: BobAlice JaneJudy

Centralized Napster model Benefits: –Low per-node state –Limited bandwidth usage –Short location time –High success rate –Fault tolerant Drawbacks: –Central point of failure –Limited scale –Possibly unbalanced load BobAlice JaneJudy

Unstructured Gnutella model Benefits: Drawbacks: Bob Alice Jane Judy Carl

Unstructured Gnutella model Benefits: –Limited per-node state –Fault tolerant Drawbacks: –High bandwidth usage –Long time to locate item –No guarantee on success rate –Possibly unbalanced load Bob Alice Jane Judy Carl

Structured FreeNet, Chord, CAN, Tapestry, Pastry model Benefits: Drawbacks: ?

Structured FreeNet, Chord, CAN, Tapestry, Pastry model Benefits: –Manageable per-node state –Manageable bandwidth usage and time to locate item –Guaranteed success Drawbacks: –Possibly unbalanced load –Harder to support fault tolerance ?

Improvements: SuperPeers KaZaA model Hybrid centralized and unstructured Advantages and disadvantages?

Other Improvements Caching indices –Push vs pull Building communities/directed search Replication of content –Enables load balancing – how?