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

In a peer-to-peer system, it is trivial to find the location of the source computer or node that carries/stores a particular data item. Discussed in the paper [1], is a distributed lookup protocol called Chord, which was described to provide and support a single operation. This operation involves the mapping of a key onto a node when given a key. As mentioned by the authors of the paper, the Chord protocol uses consistent-hashing technique (i.e., SHA-1) in assigning keys to Chord nodes, which in effect balances the load of the nodes since all of them receive the same number of keys.

Based on their conducted experiments and simulations, Chord was said to be adaptable to system changes. They also confirmed that Chord scales well with the number of nodes; recovers from large numbers of simultaneous node joins and failures; and returns most looups correctly.

Also, based on the discussed features of the Chord protocol, it appears that Chord does not only have a very well-thought system design but is also a very attractive protocol that can be implemented in a large-scale distributed peer-to-peer systems or applications.

Further, Chord seems to be suited in other applications such as in the field of mobile adhoc networks. In this regard, future researchers may extend Chord's functionalities in the implementation of MANET's.

Reference:
[1] Ion Stoica, Robert Morris, David Karger. M. Frans Kaashoek, and Hari Balakrishnan. Chord: A Scalable Peer-to-Peer Lookup Service for Internet Applications. AACM SIGCOMM '01. August 2001.