One of the challenges for 3D multi-user virtual simulation environments (3D MUVEs) developers is to keep the shared virtual simulation environment synchronized among all the participating users? terminals. Support to 3DMUVEs through traditional client-server communication model offers simpler management but can lead to bottlenecks and higher latencies. Peer-to-peer communication model, on the other hand, offers no central coordination but are more complex to manage. Current peer-to-peer networks, such as KaZaA and Gnutella, provide multimedia sharing services but do not support multiuser 3D virtual environment applications.

This paper describes a solution to support 3D MUVEs in a hybrid peer-to-peer Gnutella network, which provides session control and distributed shared virtual environment synchronization. As a result of this work, two components specified by the ongoing multi-user extension to the MPEG-4 standard were implemented and integrated to the Gnutella network for control and synchonization. This solution minimizes the disadvantages of client-server, pure peer-to-peer and proxy-based models. The results show the number of users per session that can be supported with acceptable delays for tasks such as collaborative editing and for highly interactive applications such as action games.