Flow control signals in half-duplex and full-duplex networks are initiated and maintained based on the detected number of data bytes stored in a receive buffer from payload data of received data packets. If the number of stored data bytes exceeds a predetermined threshold, the network interface initiates flow control. Alternatively, the decision to initiate flow control may be based upon the rate at which the receive buffer is emptied compared to the number of stored data bytes in the receive buffer, or the rate the data bytes are stored into the receive buffer. The duration of the flow control is calculated as a wait time interval selected in response to the number of stored data bytes. The wait time may be selectively set as an integer multiple of slot times, or as a time interval based on the number of stored data bytes relative to the removal rate. Hence, the precise control and the initiation of the flow control for a specific wait time prevents loss of transmitted data while maintaining network throughput.