2-Chord Halved

We present 2-Chord Halved, a distributed peer-to-peer lookup, protocol. Our proposal is based on Chord [24] exhibit the following advantages: i) We show a stabilization procedure that eliminates the fixfinger procedure of Chord protocol. Our strategy allows to inform each node on the ring that is interested to a topological change. Fixfinger in Chord costs O(log(2) N) messages when it is ran on all finger table entries even if the finger table is up to date, contrariwise our stabilization procedure, that has the same cost, is ran only if there are join or leave operations and only on the interested nodes. ii) We present a new strategy to implement the join/leave operations using the predecessor's finger table of joined node and exploiting the fingers of predecessor as start point searching new fingers. This procedure costs O(log N log log N) w.h.p., contrariwise to Chord within join/leave operation cost O(log(2) N) w.h.p.. iii) We show a new routing strategy that has a moderate improvement on average path length. The improvements are obtained with no harm to the operational efficiency (e.g. stability, scalability fault-tolerance, node congestion) of the Chord systems.