PURPOSE: To provide a high throughput by using a cell abort rate for a parameter for route selection without use of a parameter for route selection having been adopted for a conventional ATM communication network.

CONSTITUTION: Since a traffic characteristic of an ATM network is sensitive to a cell abort rate, the call connection control is implemented based on the cell abort rate. A route having a smallest cell abort rate is selected among routes between outgoing and incoming call nodes in pairs making a setup request by the routing control. Buffers CLR2, CLR2 are provided respectively to a pre-stage and a post-stage of an ATM switch 11. Furthermore, each buffer is provided with multi-kind processing units 1, 2. A multi-path switch in which plural routes are in existence between input and output ports estimates a cell abort rate to each route and selects a route whose cell abort rate is minimum. It is estimated by assuming the multi-kind processing units 1, 2 having a large cell flow in a relevant link.