GFRT-chord: Flexible Structured Overlay Using Node Groups

A fundamental problem in structured overlays is how to reflect the physical environment when nodes forward messages based on logical positions, independent of physical machines and physical network components. If the number of node groups that forward messages is reduced, costs are reduced for the entire network. However, when designing such an efficient algorithm, the characteristics of existing structured overlays, which makes routing inefficient in cases where there are too few nodes or too many entries in routing tables, prevents the use of the algorithm in practical applications. We propose GFRT-Chord, a routing algorithm for structured overlays based on the flexible routing tables (FRT) framework. GFRT-Chord provides a logarithmic path length in two typical network-growth models and forwarded messages never pass through a group more than once. We have evaluated GFRT-Chord with various pairs of parameters. Furthermore, we have implemented a naive grouped FRT-Chord, a simpler FRT-based algorithm than GFRT-Chord. We demonstrate that the performances of the naive grouped FRT-Chord is approximately the same as that of the GFRT-Chord, however there are specific pairs of network parameters and maximum routing table size that result in a path length that is significantly longer than that of the GFRT-Chord.