Modeling dialup internet access: an examination of user-to-modem ratios, blocking probability, and capacity planning in a modem pool

In the near future, dialup connections will remain as one of the most popular methods of remote access to the Internet as well as to enterprise networks. The dimensioning of modem pools to support this type of access is of particular importance to commercial Internet service providers as well as to universities that maintain their own modem pools to support access by faculty, staff, and students. The primary contribution of this paper is to analyze how network administrators may decrease the probability of blocking for access to the pool by imposing session limits restricting the maximum duration of the online session. Session limits may provide a viable alternative to improving network performance without necessarily adding capacity to the pool. Blocking probability is examined under a number of different scenarios to assess potential improvements in the quality of service by imposing session limitations during peak-period operations.