Point-to-multipoint arbitration

Abstract

An Asynchronous Transfer Mode switch and method which facilitate point-to-multipoint transmission are disclosed. The switch includes a bandwidth arbiter, and each input port within the switch includes a switch allocation table ('SAT') which controls bandwidth allocation between input and output ports. Each SAT includes a plurality of sequentially ordered cell time slots and a synchronized pointer which is directed to one of the slots such that at any given point in time each of the pointers is directed to the same slot location in the respective SAT with which the pointer is associated. To execute point-to-multipoint operation the bandwidth arbiter maintains a list of connections and bit vectors indicating the designated destination ports for a point-to-multipoint cell. The list maintained by the bandwidth arbiter is then compared to an unassigned output port bit vector generated from the SATs to determine matches therebetween, at which point-to-multipoint transmission may be made by utilizing instantaneously unused bandwidth within the switch while arbitration distributes bandwidth among competing point-to-multipoint connections. The bandwidth arbiter may also assign priority to connections in the list.