Chord: A Scalable Peer-to-peer Lookup Service for Internet Applications

Chord is a scalable lookup protocol that supports the operation of mapping a given key onto a node. It is fully distributed and attempts to load balance by acting as a distributed hash function. Nodes only need to keep track of a few successor nodes on the circle, which they maintain in a finger table. Chord allows for a dynamic network; it correctly maintains each node's sucessor and ensures that a node is responsible for every key. It uses stabilization to keep nodes' successor pointers correct but also allows for lookup retries in the event that stabilizing has not happened recently enough. This paper contained a lot of theoretical analysis about Chord in addition to simulation/experimental results, and the authors use these analyses to back up the idea that Chord functions correctly even in the face of incorrect or failed nodes.