Abstract: A switching fabric circuit that provides on-the-fly switching of packets, an expandable number of ports, and the interconnection of heterogeneous LAN segments. The switching fabric circuit includes a switching link that comprises a switching bus and a plurality of packet processors, wherein each packet processor is coupled between the switching bus and a LAN segment. The switching bus is a time division multiple access (TDMA) bus, and arbitration for switching bus access is distinct from arbitration for access to the ports of the switching fabric circuit. Switching bus arbitration is done according to one of two priority levels, wherein high priority requests are guaranteed access to the switching bus during a synchronization period in which the high priority requests are made. This provides for guaranteed throughput and on-the-fly switching of packets. Port arbitration may be either uniport port arbitration or multiport port arbitration.