Flexible routing tables: Designing routing algorithms for overlays based on a total order on a routing table set

This paper presents Flexible Routing Tables (FRT), a method for designing routing algorithms for overlay networks. FRT facilitates extending routing algorithms to reflect factors other than node identifiers. An FRT-based algorithm defines a total order on the set of all patterns of a routing table, and performs identifier-based routing according to that order. The algorithm gradually refines its routing table along the order by three operations: guarantee of reachability, entry learning, and entry filtering. This paper presents FRT-Chord, an FRT-based distributed hash table, and gives proof that it achieves O(log N)-hop lookups. Experiments with its implementation show that the routing table refining process proceeds as designed. Grouped FRT (GFRT), which introduces node groups into FRT, is also presented to demonstrate FRT's flexibility. GFRT-Chord resulted in a smaller numbers of routing hops between node groups than both Chord and FRT-Chord.