Interlayer-coordinated communication-line switching in a network including two layers, each having a switching function. In the present invention, a communication apparatus which (1) is connected with a network including (i) lower layer apparatuses which are connected with communication lines of a lower layer and communication lines of an upper layer and conducts line switching in the lower layer and (ii) upper layer apparatuses which are connected with the communication lines of the upper layer and have means for line switching in the upper layer and (2) detects line failure and coordinates line switching using failure information on the lower and upper layer communication lines.