Introduction

Nowadays distributed hash table (DHT) [1, 2] plays an important role in distributed systems and applications, especially in large-scale distributed environments. In the normal Client/Server model (C/S model) since the central server is in charge of most of the resources, it becomes the most important part as well as the bottleneck and weak point of the system. On the contrary, the distributed model (a typical one is the peer-to-peer (P2P) model [3, 4]) distributes the resources on the nodes in the system. The distributed model provides better robustness and more efficiently utilizes all peers’ capability, while the resources of the clients are idle in C/S mode. In distributed environments a key problem is how to manage the resources efficiently, which is a particular important issue in large-scale systems. DHT addresses this problem and promotes the development of P2P greatly.