This paper describes the motivations and the design of a communication architecture for Large-Scale Virtual Environments on the Internet. We propose an approach at the transport-layer, using multiple multicast groups and multiple agents. Our approach involves the dynamic partitioning of the virtual environment into spatial areas and the association of these areas with multicast groups. In our work, we describe a method based on the theory of planar point processes, to determine an appropriate cell-size so that the incoming traffic at the receiver side remains with a given probability below a sufficiently low threshold.