Making networked virtual environments work

Collaborative virtual environments (CVEs) are a promising technology enabling remote participants to share a common place through three-dimensional graphical scenes. Within the COVEN project (Normand, 1999), we have run prolonged series of Internet trials that have allowed us to gather valuable data to formulate usability guidelines and networking requirements. However, running such trials in a real setting and making sure that the application and networking infrastructures will be stable enough is still a challenge. In this paper, we describe some of our experiences, together with the technical choices that have permitted many hours of successful Internet trials. We also make a thorough analysis of different correlated logging data. This analysis allows us to propose and confirm a model of a CVE application's network behavior, together with a number of interesting results that disprove some common assumptions. Furthermore, we use the model and the logging data to highlight the benefits of IP multicasting and for predicting traffic behaviors and bandwidth use on top of different logical network topologies.