Scalability of a distributed virtual environment based on a structured peer-to-peer architecture.

We investigate the scalability of distributed virtual environments (DVEs), which are based on a structured peer-to-peer (P2P) overlay. We are interested in the average network load and routing latency and how they depend on the number of hosts in the DVE. To this end, we study a prototypical DVE consisting of a simple game scenario and a P2P architecture based on Pastry and Scribe as proposed by Knutsson et al. in their important work ”Peer-To-Peer Support for Massively Multiplayer Games”[3]. Both our theoretical analysis and simulation results show that the network load as well as the routing latency grow O(log(N)), where N is the number of hosts (c.f. figure 6.9 and 6.11). Our results are in partial contradiction to those given by Knutsson et al. As shown in Fig. 6.9, their experimental results of average message rate are constant for 1000 and 4000 hosts, while ours scale with O(log(N)). We suppose this is due to Knutsson et al. only measuring the subscriber message rate. This is confirmed by our own theoretical analysis and measurement of the subscriber message rate, which display the same O(1) behavior as seen in Fig. 6.9.