Routing table construction method solely based on query flows for structured overlays

In structured overlays, nodes forward a query hop by hop to deliver it to the responsible node for the query. Each node maintains its routing table and determines the next hop by referring to the routing table. Each node has its node identifier and determines which other nodes to be on its routing table based on node distance, that is defined by difference of node identifiers or the number of nodes between two nodes in identifier order. In existing structured overlays, routing table construction and maintenance based on node distance enable efficient lookup, that is a small number of hop counts to the responsible node. We found out that efficient lookup does not require node distance in routing table construction and maintenance. As an example, this paper presents Flow-based Flexible Routing Tables (FFRT), a routing table construction method solely based on query flows. In an FFRT-based overlay, a node calculates query flows, that is the amount of queries forwarded to each node on its routing table. And the node maintains its routing table toward a state in which all nodes on the table have equal query flows. FFRT also provides such a practical merit as it performs efficient lookups though node and queries´ target identifiers are distributed nonuniformly. The merit enables range query support.