Mit-lcs-tr-819 Chord: a Scalable Peer-to-peer Lookup Service for Internet Applications

Efficiently determining the node that stores a data item in a distributed network is an important and challenging problem. This paper describes the motivation and design of the Chord system, a decentralized lookup service that stores key/value pairs for such networks. The Chord protocol takes as input anm-bit identifier (derived by hashing a higher-level applicationspecific key), and returns the node that stores the value corresponding to the key. Each Chord node is identified by anm-bit identifier and each node stores the key identifiers in the system closest to the node’s identifier. Each node maintains anmentry routing table that allows it to look up keys efficiently. Results from theoretical analysis, simulations, and experiments show that Chord is incrementally scalable, with insertion and lookup costs scaling logarithmically with the number of Chord nodes.