This paper presents a finite buffer M/G/1 queue with two classes of customers who are served by a combination of head-of-the-line priority and buffer reservation schemes. This combination gives each class of customers high or low priorities in terms of both delay and loss. The scheme is analyzed for the model in which one class of customers has high priorities over the other class of customers with respect to both delay and loss. First, steady-state joint probability distribution of the number of each class of customers in the buffer and remaining service time is derived by a supplementary variable method. Second, loss probability and mean waiting time for each class of customers are provided using this probability distribution. Finally, a combination of head-of-the-line priority and buffer reservation schemes is numerically compared with other buffer management schemes in terms of admissible offered load to show its effectiveness under differing QoS requirements.

This paper analyzes a finite buffer M/G/1 queue with two classes of customers who are served by a combination of head-of-the-line priority and push-out schemes. This combination gives each class of customers two different types of priorities with respect to both delay and loss. There are two models considered. The first one is that one class of customers has a higher priority over the other class with respect to both delay and loss; the second one is that one class has a higher priority with respect to loss and the other has high-priority with respect to delay. For both of these models, the joint probability distribution of the number of customers of both classes in the buffer is derived by a supplementary variable method. Using this probability distribution, we can easily calculate the loss probabilities of both classes, the mean waiting time for high-priority customers with respect to loss and the upper bound for mean waiting time for low-priority customers with respect to loss. Numerical examples demonstrate an effect of the combination of different types of priorities.