Performance monitor system, transmission device and performance monitor method of transmission line

摘要

The present invention is a transmission system with a performance monitor function. The system has an end office, an opposite office located opposite the end office and an intermediate office located between the end office and the opposite office. In the transmission system each of the end office, the opposite office and the intermediate office has a transmitter/receiver for transmitting/receiving information and a performance monitor for monitoring performance of a transmission line. The intermediate office has a switch for switching lines and a bypass for bypassing the switch and for transmitting/receiving a signal to/from an adjacent office while the performance monitor is operating.