Towards Minimum Traffic Cost and Minimum Response Latency: A Novel Dynamic Query Protocol in Unstructured P2P Networks

Controlled-flooding algorithms are widely used in unstructured networks. Expanding ring (ER) achieves low response delay, while its traffic cost is huge; dynamic querying (DQ) is known for its desirable behavior in traffic control, but it achieves lower search cost at the price of an undesirable latency performance; Enhanced dynamic querying (DQ+) can reduce the search latency too, while it is hard to determine a general optimum parameters set. In this paper, a novel algorithm named selective dynamic query (SDQ) is proposed. Unlike previous works that awkwardly processing floating TTL values, SDQ properly select an integer TTL value and a set of neighbors to narrow the scope of next query. Our experiments demonstrate that SDQ provides finer-grained control than other algorithms: its latency is close to the well-known minimum one via ER; in the mean time its traffic cost also close to the minimum. To our best knowledge, this is the first work capable of achieving best performance in terms of both response latency and traffic cost. In addition, our experiments also demonstrate that SDQ works well in various network topologies.