The author study a M/G/1 queueing system with vacations, in which the sojourn time of the server at the queue is controlled by a timer. They consider three policies for setting the timer value: time-limited (TL), cycle-time-limited (CL) and cycle-time-limited with accumulated lateness (CLL). When the server arrives at the queue, the timer is set to a certain value depending on the policy employed. The server serves the waiting customers until either the system becomes empty, or the timer expires, whichever occurs first. In the latter case, the server completes the service on the customer being served, then takes a vacation. Customers are not served during the vacation. If the system is empty upon the server's return from a vacation, another vacation begins immediately. Such a queueing system finds applications in the performance analysis of local area network protocols such as the IEEE 802.4 (token bus) and the Fiber Distributed Data Interface (FDDI), in which the vacation would correspond to the time the token is away at other stations. Using the matrix-analytic approach, they compute the probability distribution of the number of customers in the system at an arbitrary point in time, and the distribution of the time the server spends at the queue before he takes a vacation.>

Polling systems have been used to model a large variety of applications and much research has been devoted to the derivation of efficient algorithms for computing the delay measures in these systems. Recent research efforts in this area, which have focused on the optimization of these systems, have raised the need for very efficient such algorithms. This work develops the descendant set approach as a general efficient algorithm for deriving all moments of customer delay (in particular, mean delay) in these systems. The method is applied to a very large variety of model variations, including: 1) The exhaustive and gated service policies, 2) Fractional service policies, 3) The cyclic visit order, 4) Arbitrary periodic visit orders (polling tables), and 5) Customer routing. For most of these variations the method significantly outperforms the algorithms commonly used today.>

A network modeling tool, called NetMod, which uses simple analytical models to provide the designers of large interconnected local area networks with an in-depth analysis of the potential performance of these systems is presented. This tool can be used in either a university, industrial, or governmental campus networking environment consisting of thousands of computer sites. NetMod is implemented with a combination of the easy-to-use Macintosh software packages, HyperCard, and Excel. The objectives of NetMod, the analytical models, and the user interface are described in detail, along with its application to an actual campus-wide network.>

The use of queueing network models to analyze the performance of computer systems is widespread. Typically the analysis requires certain assumptions to be made. Even under such assumptions, the exact analysis of these models for the performance measures could be quite time consuming, especially when various alternate configurations of the system are to be evaluated. In some situations, bounds on the performance may often be adequate. This issue of obtaining reasonable bounds has hence been the subject of some discussion and a number of bounding techniques have been proposed over the past few years. In this paper we present a bounding technique for networks with a single class of customers that appears to be more effective than techniques previously reported.