Priority queueing with finite buffer size and randomized push-out mechanism

The non-preemptive priority queueing with a finite buffer is considered. We introduce a randomized push-out buffer management mechanism which allows to control very efficiently the loss probability of priority packets. The packet loss probabilities for priority and non-priority traffic are calculated using the generating function approach. In the particular case of the standard non-randomized push-out scheme we obtain explicit analytic expressions. The theoretical results are illustrated by numerical examples. The randomized push-out scheme is compared with the threshold based push-out scheme. It turns out that the former is much easier to tune than the latter. The proposed scheme can be applied to the Differentiated Services of the Internet.