Despite recent excitement generated by the peer-to-peer (P2P) paradigm and the surprisingly rapid deployment of some P2P applications, there are few quantitative structure of the Gnutella network make it an interesting P2P architecture to study. Like most other P2P applications, Gnutella builds, at the application level, a virtual network with its own routing mechanisms. The topology of this overlay network and the routing mechanisms used have a significant influence on application properties such as performance, reliability, and scalability. We describe techniques to discover and analyze the Gnutella's overlay network topology and evaluate generated network traffic. Our major findings are: (1) although Gnutella is not a pure power-law network, its current configuration has the benefits and drawbacks of a power-law structure, (2) we estimate the aggregated volume of generated traffic, and (3) the Gnutella virtual network topology does not match well the underlying Internet topology, hence leading to ineffective use of the physical networking infrastructure. We believe that our findings as well as our measurement and analysis techniques have broad applicability to P2P systems and provide useful insights into P2P system design tradeoffs.