Cell discarding policies supporting multiple delay and loss requirements in ATM networks

Future ATM networks will carry a wide range of applications which could differ significantly in their delay and loss requirements. In such an environment, supporting multiple delay requirements as well as loss requirements becomes indispensable to the priority mechanisms such as cell discarding policies employed in ATM switches. Traditional cell discarding policies, such as last-in-first-out (LIFO), pushout, threshold, and QoS schemes, cannot support multiple delay bounds efficiently. In this paper, we generalize traditional schemes and propose four new policies, termed G-LIFO, G-pushout, G-threshold and G-QoS scheme, respectively. We show that when coupled with the earliest-deadline-first service scheduling discipline these four new policies can support multiple delay and loss requirements more efficiently than their conventional counterparts. We prove that the G-QoS scheme is optimal in terms of efficiency among all generalized space-conserving, stable schemes and also optimal among all stable schemes if all traffic flows are equally demanding. Simulation studies are conducted to examine the performance of the proposed cell discarding policies