Babelchord: a social tower of DHT-based overlay networks

Chord is a protocol to distribute and retrieve information at large scale. It builds a large but rigid overlay network without taking into account the social nature and the underlying topology of large platforms, made of the interconnection of many independent smaller networks. Thus, new approaches are required to build overlay networks. In this paper, we propose Babelchord, a more flexible and social overlay interconnecting different Chord networks, which are floors of a social tower. Peers can belong to several floors, allowing this interconnection. By connecting smaller structured overlay networks in an unstructured way, it provides a costeffective alternative to hierarchical structured P2P systems requiring costly merging. Routing of lookup messages is performed as in Chord within one floor, but a peer belonging to several floors forwards the request to the different floors it belongs to. These co-located peers act as a sort of neural synapse. Results from simulations show that Babelchord scales up logarithmically with the number of Babelchord peers. Moreover a small number of synapses is enough to ensure a high exhaustiveness level.