Reference Work Entry

Encyclopedia of Parallel Computing

pp 1498-1506

Peer-to-Peer

  • Stefan SchmidAffiliated withComputer Science, Telekom Laboratories/TU Berlin
  • , Roger WattenhoferAffiliated withComputer Science, Telekom Laboratories/TU Berlin

Synonyms

Distributed hash table (DHT); Overlay network; Decentralization​; Open distributed systems; Consistent hashing

Definition

The term peer-to-peer (p2p) is ambiguous, and is used in a variety of different contexts, such as:
  • In popular media coverage, p2p is often synonymous to software or protocols that allow users to “share” files (music, software, books, movies, etc.). p2p file sharing is very popular and a large fraction of the total Internet traffic is due to p2p.

  • In academia, the term p2p is used mostly in two ways. A narrow view essentially defines p2p as the “theory behind file-sharing protocols.” In other words, how do Internet hosts need to be organized in order to deliver a search engine to find (share) content (files) efficiently? A popular term is “distributed hash table” (DHT), a distributed data structure that implements such a content search engine. A DHT should support at least a search (for a key) and an insert(key, object) operation. A DHT has many a ...

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