1“Commonly Used P2PCommunicationsmethods & Program”By Farhan Afzal Saifee 090301067Instructor : Dr. Ezgi Deniz Ulker
2CONTENTS• What is Peer to Peer?- Properties of Peer to Peer• Knowledge of Client – Server Architecture.• How does Internet P2P works?• Peer to Peer Systems Modes- Centralized, Decentralized or Hierarchical• Types of Peer 2 Peer Network.• Commonly Used Peer to Peer Programs.
3What is Peer to Peer?• The term Peer refers to a user computer• Peer to Peer defines a communication (exchange ofinformation) that takes place between two or more nodesat a particular time without a dedicated server.• In that case a Peer can be Client and a Server at thesame time (Servant)• Many P2P networks (including the original Napster) arenot pure peer networks as they somehow utilize centralservers for some functions
4Properties of Peer to Peer Systems1. Unreliable, uncoordinated, unmanaged- No central authority, peers are completely independent- Increases flexibility of individual peers.2. Large collection of resources-Voluntary participation, global reach-Millions of simultaneous users3. Network is dynamic: nodes enter and leave the network“frequently” and Nodes are Anonymous.
5Knowledge of Client - Server• It is a system that includes aclient and a server, and theclient-server model works as aseries of transactions betweenthe two.1. The client initiates thetransaction by sending arequest to the server,2. And the server, which is alwaysin a state of readiness to acceptrequests, responds by providinga service or resource to theclient.
6How does Internet P2P Works.1. User downloads and executes a peer-to-peer networkingprogram (Gnutellanet )2. User enters the IP address of another computerbelonging to the network. (Must know 3 - 5 Addresses)3. Once the computer finds another network member on-line, it will connect to that users connection (who hasgotten their IP address from another users connectionand so on).4. Users can choose how many member connections to seekat one time and determine which files they wish to shareor password protect.
7Peer to Peer System Modes.Peer to PeerSystemCentralizedArchitectureBrokeredArchitectureNapsterDe-CentralizedArchitectureFreenet, GnutellaHierarchicalKazaa , Skype
8 Centralized model Global index held by acentral authority(single point of failure) Brokered Architecture direct contact betweenrequestors and providers Example: NapsterP2P System models (1)
9How Napster Works0 – Every Servant is registeringto the broker1 – Servant contacts the brokerthat has the information of theresources held by otherservants who are registered tothe broker2 - Broker responds to theservant, sends the IP address ofa servant that has the desiredfile.3 – The downloading processtakes place.
10P2P System models (2) Decentralized model Examples: Gnutella no global index, no central coordination, Interactiontakes place between the nodes Direct contact between requestors and providers(Gnutella)0 - Starts to search servant thatkeeps the resource. When it findsthe data, it’s private address isgiven back.1 - Resource and address known,they started to communicate (filetransmission).
11P2P System models (3) Hierarchical model Introduction of “super-peers” or “Super-Nodes” Mix of centralized and decentralized model Example: FastTrack Protocol,Kazaa
12Types of Peer to Peer NetworkPeer-to-peer networks come in three flavors. The categoryclassification is based on the network and application.• Collaborative Computing Also referred to as distributed computing, it combinesthe idle or unused CPU processing power and/or freedisk space of many computers in the network.• Instant Messaging where software applications, such as MSN Messengeror AOL Instant Messenger, for example, allow users tochat via text messages in real-time• Affinity Communities One of the group of P2P networks that is basedaround file-sharing
13Commonly Used Peer to Peer Programs.1. BitTorrent2. Ares3. Limewire4. Skype5. Yahoo Messenger6. Ebay Web Application7. Viber8. Tango9. FrostWire
14Commonly Used Peer to Peer Programs. “SKYPE” Skype is a peer-to-peer (p2p) VoIP client developed bythe organization that created Kazaa. It is very similar to the MSN and Yahoo IMapplications, as it has capabilities for voice-calls, instant messaging The underlying protocols and techniques it employs arequite different Two types of nodes in this overlay network, ordinaryhosts and super nodes (SN).• An ordinary host is a Skype application that can beused to place voice calls and send text messages.• A super node is an ordinary host’s end-point on theSkype network.
17“SKYPE” Cont…• Skype clearly has both peer-to-peer components as well asclient-server components• Account data is stored in central servers. But audio streamsfrom peer to peer.• The contact list, as well as the authentication, as younoticed, goes through Skypes servers