software needed to solve the technical issue of interaction among thousands of participants.
One of the primary infrastructure problems is that only a few university research groups are working in networking large-scale distributed VEs, and they are constrained in at least two ways. First, the networks are operating within extremely limited bounds—the Department of Defense (DIS) bounds; and second, they are very expensive to run. DIS is an applications protocol developed under ARPA and U.S. Army contract as the networking protocol for Department of Defense simulators. Although DIS is known to have significant problems (i.e., it is limited in capability and too large for what it needs to do), it has been made an IEEE standard. The Department of Defense is now putting all of its development resources into using this protocol for moving from the SIMNET-sized limit of approximately 300 participants (using Ethernet/T1 links) toward the 10,000 to 300,000 participant level. What is needed is a major research initiative to investigate DIS alternatives—alternatives that will allow a generalized exchange of information between the distributed participants of large-scale virtual environments. The new protocol needs to be extensible, a feature that does not appear to be a part of DIS.
A second infrastructure issue is the high cost of research into large-scale networked virtual environments. There are very few universities that can afford to dedicate the T1 lines (with installation expenses of $40,000 and operating costs of $140,000 per year) needed to support these activities. At the present time, only two universities in the United States have such dedicated resources: the University of Central Florida and the Naval Postgraduate School. Various approaches, such as an open VE network and the necessary applications protocol, should be considered for providing research universities with access to the needed facilities. Unless costs are significantly reduced, a concerted development effort on software solutions for networked VE cannot begin.
A critical ingredient in the development of large-scale networks for VE is the interest of the entertainment industry in introducing telecomputer and interactive video games into the home. To date, cooperative financial arrangements have been made between manufacturers of video games and large corporations already in the telecommunications business. The focus of these arrangements is to provide low-end, relatively inexpensive systems for large numbers of participants with an eye to making a profit. Like the Department of Defense, the video game industry is not interested in generalizability of information transfer, nor is it interested in openness and accessibility. The danger is that the video game industry will set the networking protocol standards at the low end and the Defense/DIS community will set the standards at the high end. Neither of these standards is general enough for the widespread VE application development we would like to see.