The authors analyze an M/sub 1/, M/sub 2//G/sub 1/, G/sub 2//1/N queue with different scheduling and push-out schemes. They present an exact method to compute loss probabilities, the distribution of the number of class 1 packets in the system and the mean waiting time of a class 1 packet. An approximate solution is given for the computation of the mean waiting time for class 2 packets. The model allows general service time distributions for classes 1 and 2, as well as a general service discipline and a divided buffer management scheme. Numerical examples are included, which consider the loss probabilities and mean waiting time simultaneously.>

The reliability of extra-stage interconnection networks is discussed. Three types of reliability are analyzed: terminal reliability, which is the probability that at least one fault-free path exists between a given input-output pair: network reliability, which is the probability that at least one fault-free path exists between every input-output pair; and broadcast reliability, which is the probability that at least one fault-free path exists between a given input and all outputs. A recursive expression for the broadcast reliability is obtained. Tight bounds are derived for the network reliability. The numerical results indicate that for practical networks (i.e. when network reliability is at least 0.5) the difference between the upper bound and the lower bound is no more than 2% of the lower bound.>

Consideration is given to token-passing or polling systems in which the message arrival process, the message transmission time distribution, and the walk time vary from one station to another. An approximate analysis of these systems is obtained. The results obtained from the approximate analysis are compared against both simulation results and those obtained from two approximate methods that have been proposed earlier. For the special case of a symmetric system, it is shown that the approximate analysis is exact when the walk time is constant. Even when the walk time is exponentially distributed, it is shown that the approximate analysis gives an approximation error of less than 0.3% in the range of offered load that is generally of interest.>