PURPOSE: To easily receive data by allocating many buffers to a high speed receiving queue and to prevent the generation of convergence in transmitting data by increasing a threshod for a low speed transmitting queue.

CONSTITUTION: This inter-network connecting device is provided with plural ports 1 to 4 including transmitting and receiving queues and capable of changing link access speed, a data repeating means 35 for transferring data from the receiving queues to the transmitting queues in the ports 1 to 4, a receiving buffer allocating means 12 for automatically allocating a buffer recorded in a common buffer pool to respective receiving queues in the ports 1 to 4 at the time of changing speed, and a transmitting queue threshold determining means 13 for automatically determining the threshold of each transmitting queue at the time of changing the speed. The device is also provided with a convergence detecting/evading means 38 for detecting the excess of transmitting data from the threshold of the transmitting queue and canceling the excess transmitting data and a link access speed change detecting means 11 for detecting the speed changes of respective ports 1 to 4 and informing the detected results to the means 12, 13.