Design and architecture of a new space priority mechanism for ATM network nodes

This paper presents the architecture of a new space priority mechanism intended to control cell loss in ATM switches. Our mechanism is a new generic concept called: the multiple pushout. It is based on the utilization of both AAL and ATM features and on a particular definition of the priority bit. Whenever one cell of a message overflows the buffer of an ATM switch, the algorithm causes the switch to discard other cells of the message (including later arrivals). Such discarding frees buffer spaces for cells of other messages that have a chance of arriving at their destination intact. Our objective is to emphasize that in case of overload, with most of proposed mechanisms, cells are discarded without any semantic information about the type of cells. Therefore, at the destination, all the fragments of the corrupted messages will be discarded anyway. Finally, we present simulation results comparing cell loss rates and message loss rates of several space priority mechanisms.