Peer-to-Peer (p2p) networks are the latest addition to the already large distributed systems family. With a strong emphasis on self-organization, decentralization and autonomy of the participating nodes, p2p-networks tend to be more scalable, robust and adaptive than other forms of distributed systems. The much-publicized success of p2p-networks for file-sharing and cycle-sharing have resulted in an increased awareness and interest into the p2p protocols and applications. However, p2p-networks are difficult to study due to their size and the complex interdependencies between users, application, protocol and network. This paper presents a 3-level simulator designed to study complex p2p networks.