9. Chapter 9: Peer-to-peer networks

9.4. Pure P2P architecture

  • no always-on server
  • arbitrary end systems directly communicate
  • peers are intermittently connected and change IP addresses
  • Three topics:
    • File distribution
    • Searching for information
    • Case Study: Skype

File Distribution: Server-Client vs P2P

Question : How much time to distribute file from one server to N  peers?



File distribution time: server-client

  • server sequentially sends N copies:
    • NF/us time 
  • client i takes F/di time to download



File distribution time: P2P

  • server must send one copy: F/us time 
  • client i takes F/di time to download
  • NF bits must be downloaded (aggregate)

Server-client vs. P2P: example