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Peer-to-peer networks

Peer-to-peer networks. Presented by: Saham Fazal BS (IT) 2011. introduction. A peer-to-peer network, P2P, is consider any type of network architecture composed of contributors that make a part of their resources available to other contributors on the same network without the need for a server.

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Peer-to-peer networks

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  1. Peer-to-peernetworks Presented by: SahamFazal BS (IT) 2011

  2. introduction • A peer-to-peer network, P2P, is consider any type of network architecture composed of contributors that make a part of their resources available to other contributors on the same network without the need for a server Peer-to-Peer Networks

  3. Peer-to-Peer Networks

  4. Unstructured p2p network • In an unstructured P2P network, if a peer wants to find a desired piece of data in the network, the query has to be flooded through the network in order to find as many peers as possible that share the data. • The main disadvantage with such networks is that the queries may not always be resolved. Peer-to-Peer Networks

  5. Structured p2p network • Structured P2P networks overcome the limitations of unstructured networks by maintaining a Distributed Hash Table (DHT). • whenever a peer wants to search for some data, it uses the global protocol to determine the peer(s) responsible for the data and then directs the search towards the responsible peer(s). Peer-to-Peer Networks

  6. Classification of unstructured p2p • P2P networks can be roughly classified into two types — “pure P2P networks”, and “hybrid P2P networks” • A pure p2p system is a distributed system without any centralized control. All participating peers are equal, and each peer plays both the role of client and of server. Gnutella and Freenet are examples of a pure P2P network. • There are two kinds of hybrid systems: centralized indexing and decentralized indexing. Peer-to-Peer Networks

  7. In centralized indexing a central server maintains an index of the data or files that are currently being shared by active peers. • In decentralized indexing, some of the nodes assume a more important role than the rest of nodes. They are called ” SuperNodes”. Queries are sent to supernodes, not to other peers. Peer-to-Peer Networks

  8. Famous p2p networks Peer-to-Peer Networks

  9. napster • It was used primarily for file sharing • hybrid p2p network • Ways of action: • Client sends server the query, server responds to client • Client gets list of clients from server • All Clients send IDᾼs of the data they hold to the server and when client asks for data, server responds with specific addresses • peer downloads directly from other peer(s) Peer-to-Peer Networks

  10. Peer-to-Peer Networks

  11. Napster subscribers also receive access to more than fifty commercial-free radio stations. Users can pause, play, fast-forward and rewind the radio stations at any time. Peer-to-Peer Networks

  12. Advantages and drawbacks • Advantages: • Efficient search • Limited bandwidth usage • No per-node state • Drawbacks: • Central point of failure • Limited scale Peer-to-Peer Networks

  13. gnutella • Gnutella is a file sharing protocol. • When a user wishes to find a file, the user issues a query for the file to the Gnutella users about which it knows. Those users may or may not respond with results, and will forward the query request to any other Gnutella nodes they know about. • A query contains a Time-To-Live (TTL) field and will be forwarded until the TTL has been reached. Peer-to-Peer Networks

  14. Peer-to-Peer Networks

  15. Advantages and drawbacks • Advantages: • Fault tolerant • No single point of failure • Anonymity • Drawbacks: • High bandwidth usage • Long time to locate item • No guarantee on success rate Peer-to-Peer Networks

  16. freenet • Freenet represents the purest form of P2P system. • The primary mission of Freenet is to make use of the system anonymous. • Each file in the Freenet system is identified by a key. These are typically generated using the hash function. Typically a user starts by providing a short text description of the file. This description is then hashed to generate a key pair. Peer-to-Peer Networks

  17. Freenet is able to optimize searches by creating routing tables. When a file is successfully located by a search, the file's key is inserted into a local routing table. • When a search is received by a node that contains the desired file, it returns the entire file as a successful result. Peer-to-Peer Networks

  18. Peer-to-Peer Networks

  19. Advantages and drawbacks • Advantages: • complete decentralization • fault tolerance • anonymity • scalability (to some degree) • Drawbacks: • questionable efficiency & performance • rare keys disappear from the system Peer-to-Peer Networks

  20. kazaa • Kazaa uses peer-to-peer (P2P) file sharing -- the same type of technology that made Napster famous. • The system divides Kazaa users into two groups: supernodes and ordinary nodes. Peer-to-Peer Networks

  21. When the computer sends out a request for files the user wants to download or upload, the request is funneled through the supernode. The supernode communicates with other supernodes, which in turn connect to regular nodes that in turn connect to even more regular nodes. • Once the correct file has been located, it is transferred directly from the file owner to the requester, it doesn't have to go through a supernode. Peer-to-Peer Networks

  22. Peer-to-Peer Networks

  23. Skype: p2p voip • Skype is a peer-to-peer (p2p) VoIP, developed by the organization that created Kazaa. • Better voice quality than other VoIP clients • There are two types of nodes, ordinary hosts and super nodes (SN). Peer-to-Peer Networks

  24. An ordinary host must connect to a super node and must authenticate itself with the Skype login server. • The Skype login server is not a Skype node. It stores usernames and passwords as well as buddy lists. • Each SC maintains a table of reachable nodes called host cache (HC). • An HC contains IP addresses and port numbers of super nodes. Peer-to-Peer Networks

  25. bittorrent • The basic idea in BitTorrent is to divide a single large file into pieces. • The set of peers attempting to download the file do so by connecting to several other peers simultaneously and download different pieces of the file from different peers. Peer-to-Peer Networks

  26. BitTorrent distinguishes between two types of peers, namely downloaders and seeds. • Downloaders are peers who only have a part (or none) of the file. • Seeds are peers who have all the pieces of the file but stay in the system to allow other peers to download from them. Peer-to-Peer Networks

  27. BitTorrent uses a centralized software called the tracker. • In a BitTorrent network, a peer that wants to download a filefirst connects to the tracker of the file. The tracker then returns a random list of peers that have the file. • A downloader then requests pieces which it does not have from all the peers to which it is connected. Peer-to-Peer Networks

  28. Advantages and drawbacks • Advantages: • Highly Efficient • Ability to download and upload large files in a shorter amount of time • More successful transfers • Drawbacks: • Lack of anonymity • Viruses easily spread Peer-to-Peer Networks

  29. refrences • A Survey and Comparison of Peer-to-Peer Overlay Network Schemes • Modeling and Performance Analysis of BitTorrent-Like Peer-to-Peer Networks • Secure Routing for Structured Peer-to-Peer Overlay Networks • SKYPE VoIP: • An Analysis of the Skype Peer-to-Peer Internet Telephony Protocol Peer-to-Peer Networks

  30. Thank you... Peer-to-Peer Networks

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