A fundamental problem that confronts structured peer-topeer system that use DHT technologies to map data onto nodes is the performance of the network under the circumstance that a large percentage of nodes join and fail frequently and simultaneously. A careful examination of some typical peer-to-peer networks will contribute a lot to choosing and using certain kind of topology in special applications. This paper analyzes the performance of Chord[7] and Koorde[2], and find out the crash point of each network through the simulation experiment.

There are many structured P2P systems that use DHT technologies to map data items onto the nodes in various ways for scalable routing and location. Most of the systems require O(log n) hops per lookup request with O(log n) neighbors per node, where n is the network size. In this paper, we present a constant-degree P2P architecture, namely Cycloid, which emulates a cube-connected cycles (CCC) graph in the routing of lookup requests. It achieves a time complexity of O(d) per lookup request by using O(1) neighbors per node, where n=d