A packet communication exchanging apparatus includes: a common communication channel through which a plurality of data packets are communicated; a plurality of input modules coupled to the common communication channel, for receiving the data packets and transferring the data packets to the communication channel; and, a plurality of output modules coupled to the common communication channel, for temporarily storing the data packets sent from the input modules via the communication channel, and for generating and sending a dummy packet to the communication channel when the amount of the data packets temporarily stored therein exceeds a predetermined threshold value, whereby the input module detects a packet contention occurring on the communication channel due to the dummy packet supplied thereto so as to control the data packet transmission from the input module to the communication channel.