Structured peer-to-peer networks: faster, closer, smarter

Peer-to-peer (P2P) distributed hash tables (DHTs) are structured networks with decentralized lookup capabilities. Each node is responsible for a given set of keys (identifiers) and lookup of a key is achieved by routing a request through the network toward the current peer responsible for the desired key. DHT designs are usually compared in terms of degree (number of neighbors) and diameter (length of lookup paths). In this paper, we focus three other desirable properties of DHT-based systems: We first present a topology-aware DHT that routes lookup requests to their destination along a path that mimics the router-level shortest-path, thereby providing a small “stretch.” We then show how we can take advantage of the topological properties of the DHT to cache information in the proximity of the requesters and reduce the lookup distance. Finally, we briefly discuss techniques that allow users to look up resources stored in a DHT, even if they only have partial information for identifying these resources.