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Peer-to-Peer Technologies

Peer-to-Peer Technologies. Guided by: Prof. C.R.Mandal, School of Information Technology. Seminar by: Kunal Goswami (05IT6006) School of Information Technology. Outline. Introduction P2P Architecture Types of P2P Centralized Decentralized Unstructured Structured Conclusion

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Peer-to-Peer Technologies

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  1. Peer-to-PeerTechnologies Guided by: Prof. C.R.Mandal, School of Information Technology Seminar by: Kunal Goswami (05IT6006) School of Information Technology

  2. Outline • Introduction • P2P Architecture • Types of P2P • Centralized • Decentralized • Unstructured • Structured • Conclusion • References

  3. Client/Server Architecture • Client requests data from server • Server is the only data source • Very successful model • WWW, FTP etc.

  4. Limitations of Client/Server • Single point of failure • Requires administration • Unused resources. P2P tries to address some of these limitations

  5. Introduction • What is Peer-to-Peer System ? • Sharing of resources and services by direct exchange between systems • Peer can decide what data on their computer will be shared in the network • Parties have same capabilities • Peer is also known as Servent (Server+ Client)

  6. P2P Architecture • All nodes are both clients and servers • Provide and consume data • Any node can initiate the session • No centralized data source

  7. Types of Peer-to-Peer Systems • Centralized • Napster • Decentralized • Unstructured • Gnutella • Kazaa • Structured • Freenet • Chord • Pastry

  8. Napster • A way to share music files with peers • Peer uploads the list of shared files onto the Napster server • User sends search request to the server • Server replies with the information of nodes containing the file • User connects directly to remote peer and start download

  9. Napster • Central Napster server • Single point of failure • Prone to denial of service • Ensure correct results • Search is centralized • File transfer is direct (Peer to Peer)

  10. GNutella • Share any type of files • Decentralized search • Request send to neighbours • Neighbour forwards it to its neighbours. • If TTL is over request is finished. • Users with matching file replies

  11. GNutella • Decentralized system • No Single point of failure • Less Prone to denial of service • Cannot ensure correct results • Flooding queries • Increase network congestion

  12. Kazaa • Hybrid of centralized Napsters and decentralized Gnutella. • Super Nodes acts as local search server • Each super node act as a Napster server for a small network • Super nodes are chosen according to their capacity and availability • User upload the list of shared files to a super-peer • Super nodes exchange the list periodically • Peer send the query to super node

  13. Freenet • Napster, Gnutella and Kazaa don’t provide anonymity i.e.Peers know about each other • Freenet provide anonymity • Impossible to know if user is initiating or forwarding query • Impossible to know is user is consuming or forwarding data • Smart Query • Data flows in reverse path of query to the originator peer

  14. Freenet • Loosely Structured • File placements based on hints

  15. Structured P2P • Based on Distributed Hash Tables (DHT). • DHT stores (key, value) pairs • Nodes maintain the list of neighbors in routing table • Core operation: Find node responsible for a key • Key mapped to node

  16. DHT Interface • Node ID (similar to IP address) • Key (similar to filename) • Value (contents of file) • Put(key, value) • Store (key, value) at specified node responsible for the key • Value=get(key) • Retrieve value associated with key from the node

  17. DHT Applications • Distributed File Storage • Distributed databases • Service discovery • Implementations of DHT interface • Chord • Pastry • Etc.

  18. Chord • Nodes organized in an identifier circle based on node identifiers. • Hash functions ensures even distribution of nodes and keys on the circle • Lookup in table the farthest node that precedes the key • Nodes have poor network locality

  19. Pastry • Similar to Chord • Considers network locality to minimize hops message travel • New node needs to know a nearby node to achieve locality

  20. Conclusion • P2P is thought as the distribution model of the future • Enormous effort are being addressed to P2P • Still many issues are to be resolved.

  21. References • http://www.eecg.toronto.edu/~jacobsen/mie456/slides/p2p-mie.pdf • http://tisu.mit.jyu.fi/embedded/TIE370/oldlectureslides/P2PIntroduction.pdf • http://www.cs.sfu.ca/~mhefeeda/Papers/p2pSurvey.pdf • http://ntrg.cs.tcd.ie/undergrad/4ba2.02-03/p4.html • http://momo.lcs.mit.edu/regions/qlrn/node1.html • http://plum.sfsu.edu/csc835/presentations/topic7/ • http://www.webopedia.com/DidYouKnow/Internet/2005/peer_to_peer.asp • http://www.oreilly.com/catalog/peertopeer/chapter/ch01.html • http://www.cs.princeton.edu/~qlv/download/searchp2p_sigm02.pdf • www.stanford.edu/class/cs347/notes/Notes11.ppt

  22. Thank You

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