Token rings and multipoint polled lines are two widely used network interconnection techniques. The general concept of cyclic allocation processes is defined and used to characterize token passing and polling in these networks. Scan time, the time to poll all nodes at least once, is an important quantity in the response time analysis of such networks. We derive expressions for the mean and variance of scan times using a direct, operational approach. Resulting expressions are general and are applicable to both exhaustive and non-exhaustive service. The effect of higher level protocols is easily incorporated in the analysis via calculations of constituent quantities. The expression for mean scan time is exact and depends only on the means of message transmission times and arrival rates. The approximate analysis of variance takes into account the correlation between message transmissions at different nodes. Expected level of accuracy is indicated by an example.

An important analytic model of finite buffer systems is a multiclass single queue with typed servers. In the context of such a model, we address the problem of selecting an optimal buffer sharing policy. We show that with respect to weighted throughput, an optimal policy must be a stationary delayed resolution policy. An iterative procedure based upon the policy iteration method for Markov processes with rewards is used to efficiently search for the optimal delayed resolution policy for a given set of system parameters. A performance comparison of the optimal delayed resolution policy with other well-known buffer sharing policies is also provided.

A class of policies called stationary delayed resolution policies have been proposed recently for sharing finite number of buffers at a store-and-forward node in a message switching network [9]. It has been shown that with respect to the total weighted throughput these policies comprise the optimal class of policies. In this paper, we present methods to obtain an optimal policy from the class of stationary delayed resolution policies for given values of the parameters.

Most of the analysis of buffer sharing schemes has been aimed at obtaining the optimal operational parameters under stationary load situations. It is well known that in most operating environments the traffic load changes. In this paper, we address the problem of updating buffer allocation as the traffic load at a network node changes. We investigate the behavior of a complete partitioning buffer sharing scheme to gain insight into the dependency of the throughput upon system parameters. The summary of the analysis is presented in the form of a heuristic. The heuristic is shown to perform reasonably well under two different types of stress tests.