Dynamic EPD threshold for UBR control

In many ATM switches, only a limited number of delay priority queues are available at each link. In order to support all five service categories defined in ATM Forum, the UBR and ABR service classes may have to be assigned to the same priority queue. In this paper we address the problem of controlling the resource sharing between UBR and ABR when both share the same FIFO queue in an ATM switch. We achieve the desired bandwidth sharing between these two classes by controlling the amount of buffer each class can occupy. In particular, we use the EDP threshold to control UBR by dropping UBR cells when this threshold is exceeded. We show that the control algorithm proposed in this paper achieves a tight control of the resource allocation between UBR and ABR.