In this paper, we examined a disconnection policy for modem pools that performs replacements: users are disconnected only if not enough modems are available for other users to connect. Our idea is certainly not revolutionary but it is nicely evolutionary. If any disconnection policy based on inactivity is to be used, a replacement scheme works best and is easy to apply in practical settings. In our study, we examined several replacement algorithms, and compared their performance in terms of busy signals and user inconvenience.
Perhaps more importantly, however, this paper studied the regularities that arise in Internet users' inactivity times. Based on our analysis, we proposed the CIRG algorithm and showed that it is a very good predictor of future idle times. Our hope is that the main elements of the CIRG approach will also find applications in other domains.