ATM multicast switching under mixed traffic with real-time cells and nonreal-time cells

In this paper, we propose a multicast ATM switching model with separate routes that can handle real-time cells (RTCs) with rigorous delay and small delay requirements, as well as nonreal-time cells (NTCs) with rigorous loss and reliability requirements. In the proposed model, arriving RTCs pass through the R-route, which does not have a buffer, while on the other hand, arriving NTCs pass through the N-route, which has input buffers at each port of the copy network. Copy requests of the RTCs up to a number of output ports are accepted. If the sum of copy requests of the RTCs in the R-route exceeds the number of output ports, the excess copy requests of the RTCs are discarded. On the other hand, if there are available input ports of the routing network where RTCs do not pass, some of the NTCs can pass through these ports. The NTCs with residual copy requests must wait at the head of input queues in the N-route and cell loss of NTCs is avoided. We assume that cell arrivals follow a Bernoulli process, and the number of copy requests of each cell is geometrically distributed. The cell loss probability and mean system delay of the proposed model under mixed traffic with RTCs and NTCs are evaluated by computer simulation and analysis. The proposed model proves able to make the mean system delay of the RTCs as small as one time slot, and to make the cell loss probability of the NTCs smaller than RTCs. Therefore, the proposed model can satisfy the different quality of service requirements of RTCs and NTCs.