System Architecture -- Peer to Peer Computing

lecture 2 -- part 3

Organization of nodes in P2P Systems

• Centralized directory
• Original Napster
• Pros
• Simple
• Cons
• O(N) states
• single point of failure

• Unstructured P2P systems
• Gnutella and its successors (flood queries)
• Pros
• Robust
• Cons
• Worst case O(n) messages per lookup

• Structured P2P systems
• Based upon Distributed Hash Tables (DHTs)
• Chord, CAN, Tapestry...

Distributed Hash Table (DHT)

• Distributed Hash Table
• Key = Hash (data)
• lookup(key) -> IP address
• send-RPC(IP address, PUT, key, value)
• send-RPC(IP address, GET, key) -> value
• Chord

• Example: BT content distribution