We consider a simple priority queueing system with two different types of t
raffic, high and low priority. Each type of traffic generates arrivals to i
ts own buffer that are modeled by continuous fluid flows. The input flow in
to the high priority buffer is Markov modulated, while the input rate into
the low priority buffer is constant. The fluid is transmitted from the buff
ers with the high priority buffer having priority over the low priority buf
fer. The problem fur the joint distribution of the buffer contents is deriv
ed and solved explicitly. Approximations are constructed for the tail behav
ior of the buffer content.