Abstract: An ATM switch and a congestion control method are provided to handle connection setup requests from other ATM devices. In the ATM switch, a congestion detecting process detects congestion of a class that has a number of the connection setup requests stored by class in the buffer equal to T(x), a predetermined number of the connection setup requests to be stored for each of the classes. A message discarding process discards the received connection setup request if it belongs to the congested class. Furthermore, a priority control method for receiving connection setup requests is provided to establish connections more efficiently. A branching process detects a port to which the connection setup request is inputted, identifies a priority class which corresponds to the port using a priority table, and stores the connection setup request in one of queues which are provided for each priority class.

Abstract: An ATM switching system provided with a plurality of call processing devices, a plurality of line interfaces for inputting and outputting an ATM cell, an ATM switch connected to the plurality of line interfaces for switching the ATM cell, and a switch control portion connected to the ATM switch, the plurality of line interfaces and a plurality of call processing devices. Requirement information related to call processing input from line interfaces is collected once in the switch control portion. The switch control portion determines to which of the plurality of call processing devices the requirement information is to be distributed based on the information related to the input-output line, a state of processing capability of the call processing device, etc. The related line interface is set directly from switch control portion through a bus based on the control information from determined one or a plurality of call processing devices.