PURPOSE: To connect diversified terminal equipments such as a line exchange system terminal equipment and a packet exchange system terminal equipment to the system by making a synchronizing signal and an asynchronizing signal resident on a loop transmission line in mixture and adopting packet exchange common use transmission for the line exchange.

CONSTITUTION: Dual optical fiber transmission lines 4 for left and right turn, photoelectric conversion sections (left, right) 41, and TDMA time division multiplex sections 42 are provided with a function allocating a line exchange of the loop transmission line and the operating area of packet exchange dynamically in response to a call from a terminal equipment under the management of a monitor control section 15. A line exchange system terminal connection section 43, a packet exchange system terminal connection section 44 and a monitor control section 45 are provided with a frame aligner and its generating function as the management of the entire network system and the period adjustment of the frame in addition to the dynamic allocation management of the transmission lines 4, and also provided with a function for the operation management of the network system and the rising and initial setting of the system as a man-machine interface.