Peer to Peer Overlay Routing ConceptsSpeaker: Vasileios KomianosSupervisor: Konstantinos OikonomouIonian University, Dept. of Informatics, PostgraduateFor the course: Distributed Networks & Algorithms
Peer to Peer Networks• The opposite of client - server architecture.• Distributed systems.• Most famous: Napster, Gnutella.
Why Overlay?• It resides on the application layer.• IP is not focused on peer-to-peer networks.• It does not represent the network’s physical topology.• Depending on the implementation it can address more objects than IPv4.
What DHT is?DHT stands for Distributed Hash Tables, imagine asuitable for p2p nets phone book.A file’s or service’s name, from now on calledGUID* or key, is being hashed and stored on theDHT. Each GUID is associated with a node’s IP.*Globally Unique Identifier
The Chord CaseChord Overlay Topology: DHT is replaced by finger table.Virtual Overlay Circle Finger table represents a part of Chord’s topology. Each Chord node needs routing information about only a few nodes. Node position depends on it’s key. Each node is responsible for keys having lower than it’s key value and greater than this of the previous node.
References George Coulouris, Jean Dollimore, Tim Kindberg (2005). Distributed Systems: Concepts and Designs, fourth edition. Addison-Wesley. Ion Stoica, Robert Morris, David Karger, M. Frans Kaashoek, Hari Balakrishnan: Chord: A scalable Peer-to- peer Lookup Service for Internet Applications. In Proceedings of ACM SIGCOMM 2001 (San Diego, California, USA, August 27-31). Bibliography Konstantinos Oikonomou, Spyros Sioutas, Ioannis Stavrakakis: Scalable Communication Cost Reduction: The Chord Case. In Ad Hoc Networking Workshop, 2009. Med-Hoc-Net 2009.