中文摘要：

利用分布式哈希表，有结构的对等（peer-to-peer简称P2P）网络具备了较短的路由长度和较好的扩展性．然而，由此产生了覆盖网络和物理网络之间的不匹配问题，它严重阻碍了在大规模环境下建立有效的对等网络．提出一种通用的、协议无关的方法来解决该问题．该方法基于节点交换机制，通过发现并实施有利于覆盖网络和物理网络匹配的节点交换来降低网络时延、提高性能．实验表明，该方法在明显降低了覆盖网络的平均时延的同时，也保证了额外开销可控．此外，若与其他协议相关的方法相结合，系统性能还可以得到进一步提高．

英文摘要：

With the help of distributed Hash table, the structured P2P （peer-to-peer） network has a short routing path and good extensibility. However, the mismatch between the overlay and physical network becomes the obstacle in the way of building an effective peer-to-peer system in a large-scale environment. In this paper, a generic, protocol-independent approach is proposed to solve this problem. This method is based on the swaps of peers. By discovering and performing the potential swaps that are beneficial to the match between overlay and physical network, it can reduce the average latency and improve the performance of the system. The experimental results show that the approach can greatly reduce the average latency of overlay networks. Moreover, the cost of overhead is controllable. Besides, if combining this approach with other protocol-dependent ones, the performance can be further improved.