A Source Routing Solution to Non-Transitive Connectivity Problems in Distributed Hash Tables

Distributed hash tables are popular third generation P2P protocols which are well understood in theory. These protocols usually assume that every node in the overlay is able to exchange messages with any other overlay node. However, this assumption is not always true for real-world networks, including the PlanetLab or the entire Internet. In these networks, the non-transitive connectivity phenomenon is experienced, in which some overlay nodes are able to exchange messages with a certain node and others are not. This turned out to be a serious problem, particularly for structured P2P overlays. Non-transitive connectivity issues were mainly ignored by P2P research for a long time, but have been intensively discussed recently. This paper suggests a new measure for the degree of non-transitive connectivity and presents a comprehensive, source routing based solution, to overcome non-transitive connectivity problems in distributed hash tables.