A novel method of data processing in a multiport data switching system having a decision making engine for controlling data forwarding between receive ports and at least one transmit port. The receive ports include an expansion port for receiving data packets from another switching system, and a high-speed port for receiving data packets at a rate higher than data rates at regular receive ports. In accordance with the method of the present invention, data blocks representing received data packets are placed in a plurality of data queues corresponding to the plurality of the receive ports. The data queues are transferred in successive time slots to logic circuitry for determining at least one transmit port. The time slots assigned to each of the plurality of receive ports includes expansion port time slots assigned to the expansion port and high-speed time slots assigned to the high-speed port. The expansion and high-speed time slots are dynamically distributed between the expansion and high-speed ports in accordance with relative data traffic at the ports. In particular, non-requested high-speed port time slots may be allocated to the expansion port, if the number of requests for high-speed port time slots is less than the number of the high-speed time slots. Similarly, non-requested expansion port time slots may be allocated to the high-speed port, if the number of requests for expansion port time slots is less than the number of the expansion port time slots.