FRAME RELAY COMMUNICATION DEVICE, FRAME RELAY SWITCHING SYSTEM, FRAME RELAY COMMUNICATION SYSTEM AND PVC STATUS CONFIRMATION PROCEDURE CONTROL METHOD

摘要

A frame relay communication device (10) transmits to a frame relay network F1 a second status inquiry message SE-F (full status display) for inquiring the normality of a first data link PVC #1 (second data link PVC #2) between it and a communicating frame relay communication device connected via the frame relay network F1 at least two times continuously. The frame relay communication device (10) receives a second response message S-F corresponding to the second status inquiry message SE-F and sent from the frame relay network (F1) and recognizes the status of the first data link PVC #1 (second data link PVC #2) based on this received result. Therefore, when the status of the first data link PVC #1 changes after a first-time second response message S-F is transmitted, the device (10) uses a second-time second response message S-F to recognize the status of the first data link PVC #1.