Quasi-optimal algorithms for input buffered ATM switches

This paper presents and evaluates a quasi-optimal policy for input buffered ATM switches, named RPA (reservation with preemption and acknowledgment), comprising an input queuing discipline and a cell scheduling algorithm. RPA is based on reservation rounds where the switch input ports can indicate their most urgent cell transfer needs, possibly overwriting less urgent requests by other input ports, and an acknowledgment round to allow input ports to determine what cell they can actually transfer toward the desired switch output port. RPA is shown to be simpler than previous proposals of input queuing policies, efficient and flexible, allowing the support of different traffic classes and packet-mode operations. The effectiveness of RPA is assessed with detailed simulations in uniform, as well as unbalanced, traffic conditions