Swedish Institute of Computer Science
Kista
Sweden 

During the past few years, many researchers have been using Virtual Reality (VR) together with network software to create Collaborative Virtual Environments (CVEs). They intend to help people that are geographically located at different places to work together. While CVE platforms and applications are on the rise and start to be used on a wider scale, there are still many technological issues that remain unsolved. To allow the number of simultaneous participants and applications to grow, many platforms have been experimenting with combining ideas such as loose consistency, no central servers and world sub-partitioning with IP multicasting. Most of these systems rely on the existence of the multicast backbone - MBone - for long distance connections. However, the generality and complexity of the MBone is often an obstacle to the establishment and testing of large-scale CVEs.

In this paper, we present the DiveBone, an application-level network architecture built as a stand-alone part of the Dive toolkit from the Swedish Institute of Computer Science. In short, the DiveBone is an application-level backbone that can interconnect sub-islands with multicast connectivity and/or single local networks. The key component of the DiveBone is the Dive proxy server, which acts as an intelligent packet multiplexer among its connected clients. Another important part of the DiveBone is an application that allows for visual analysis of the connection architecture and network traffic and enables a rich set of remote maintenance operations.

The DiveBone capabilities have been demonstrated and sucessfully used within the European ACTS project COVEN in a series of large-scale pan-european tests over the Internet, as well as in national Swedish projects using IP over experimental ATM networks. These trials have proven the usefulness and adequacy of the DiveBone in heterogeneous settings where multicast connectivity in other ways is limited.