Abstract: The invention provides a novel method of data processing in a multiport communication system having a decision making engine for controlling data forwarding between the receive ports and at least one transmit port. Data blocks representing received data packets are placed in data queues corresponding to the receive ports. The data queues are transferred one at a time in successive time slots to logic circuitry that determines the transmit ports. The time slots are dynamically allocated to the data queues in accordance with data traffic at the corresponding receive ports.

Abstract: A novel method of flow control in a multiport data switching system having a decision making engine for controlling data forwarding between receive ports and at least one transmit port. Data blocks representing received data packets are placed in a plurality of data queues to be processed by the decision making engine. The data queues allocated to the receive ports are monitored to produce a flow control threshold signal for a selected data queue to indicate a heavy traffic condition of a receive port corresponding to the selected data queue. For example, the flow control threshold signal may indicate that the receive port is close to an overflow condition. Monitoring of a selected data queue may be performed by comparing a write pointer indicating a memory location for writing the data blocks into the selected data queue with a read pointer indicating a memory location for reading the data blocks from the selected data queue.

Abstract: A network switch configured for switching data packets across multiple ports uses an external memory to store data frames. When a data frame is transmitted to the external memory, a frame header portion of the data frame is stored on the switch for processing by decision making logic. The switch memory is configured to store a number of the frame headers corresponding to each port on the switch along with frame pointer information indicating the location in the external memory where the data frame is stored.

Abstract: A novel method of overflow data handling in a multiport data switching system having a decision making engine for controlling data forwarding between receive ports and at least one transmit port. Data blocks representing received data packets are placed in data queues corresponding to the receive ports. The data queues are transferred to logic circuitry for processing in accordance with a prescribed algorithm. Then, a forwarding decision is made to determine the transmit port. An overflow bypass is provided to allow at least a portion of a data block to bypass the logic circuitry, when at least one of the data queues is in an overflow state. For example, pointers indicating memory locations for storing the corresponding received data packets may be transferred via the overflow bypass when the overflow state is detected.

Abstract: An apparatus and method for detecting runt data frames received by a network switch includes a plurality of queuing logics, corresponding to the number of ports contained in the network switch. The queuing logics transfer received data frames to a memory area of the network switch. The queuing logics also update the value of a column write pointer that indicates the number of data transfers required to store a prescribed portion of a particular received data frame in the memory area. A rules queue examines the column write pointer and determines if the particular data frame is a runt data frame. A runt indication signal is generated, after the particular data frame has been completely transferred to the memory area, in order to indicate if the particular data frame was a runt data frame.

Abstract: 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.