ATM switch and method for controlling bandwidth and connection quality ATM connection

1. Field of the Invention There is provided an ATM switch including: an input line unit for terminating ATM cells input via an input connection; an output line unit for outputting ATM cells to an output connection; and a switch unit for switching a first ATM connection formed by linking a first input connection with a first output connection via a first internal connection, to a second ATM connection, which has the same bandwidth and quality as the first ATM connection, formed by linking a second input connection with a second output connection via the first internal connection. With this arrangement, when the first ATM connection is changed by channel switching to the second ATM connection, the first internal connection at the first ATM connection before the switching is employed for the linking of the second input connection with the second output connection at the second ATM connection. Therefore, the process for releasing the first internal connection and the process for setting a new internal connection are not required, and the ATM connection can be switched in a moment.