Traffic smoothing by using inter-departure time control in ATM adaptation layer

Input traffic to an ATM network is segmented by the ATM adaptation layer (AAL) into ATM cells before being sent into an ATM switch for transmission. We propose in this paper a traffic smoothing scheme by using interdeparture time control (ITC) at AAL, which controls the length of time interval for releasing these cells to the ATM switch for transmission. To study the effects of ITC on cell loss probability (CLP) and average queueing delay for both variable and constant bit rate traffic, we construct a two-stage and two-class queueing model for the ITC design problem. Exploiting the input traffic characteristics and the mechanism of ITC and AAL, we develop a new analysis technique and its corresponding algorithm. Results of our analysis are highly consistent with those obtained by simulation. The use of ITC indeed smoothes the traffic burstiness to the ATM switch and significantly reduces the CLP. Increase in average delay incurred by ITC at AAL is negligible as compared to the end-to-end propagation delay in an ATM network.