Abstract: Measuring and analyzing the topological properties of P2P networks will provide guidelines for their further optimization and development. However, it seems infeasible to capture a complete and precise snapshot of all the P2P networks due to the variety of their protocols and the dynamic characteristics of the networks. An alternative way is to measure the specific P2P network instance by studying its protocol details and constructing a high-speed topology crawling system. In this paper, two most difficult problems confronted by the crawling systems are discussed, a P2P network topology measuring framework using the positive feedback strategy and its key algorithms are presented, based on which the measured Gnutella network is basically taken as an example, the distributed topology crawling system (called D-crawler) is implemented, and the evaluation methods of the framework are defined. The performances of various topology crawling systems are compared, and the accuracy and completeness of the D-crawler system are analyzed in detail. The results show that the D-crawler system can collect more accurate, complete, and stable topology data of the Gnutella network with relatively shorter crawling period and fewer hardware requirements. The measuring framework and algorithms can be applied to other P2P networks with slight modification of the D-crawler system.