中文摘要：

对于分层非结构化P2P网络,到目前为止,节点稳定性是影响搜索结果的一个主要原因。提出建立一种维护模型来有效提高这种分层非结构化P2P网络的稳定性。在此维护模型中,普通节点作为一个隐性的备份,在超级节点退出时,取代超级节点成为新的超级节点,使得整个网络具有较好的鲁棒性。并详细介绍了该算法的实验。同时,在一定程度上优化了分层非结构化P2P网络的搜索算法。该维护模型的核心是一个取代算法。

英文摘要：

So far in the hierarchical unstructured P2P network, the stability of nodes exerts great impact on the searching results. A substitute algorithm is proposed to improve the stability of the hierarchical unstructured P2P network, and to realize the maintenance model, in which normal nodes serve as an invisible backup. When super nodes are offline, these normal nodes would replace them as new super nodes so to keep the entire net robust. Meanwhile, this model would optimize the routing algorithm of the hierarchical unstructured P2P network.