The present invention provides a network in which the installation of working lines may be enabled based on the required traffic and the high speed switching of the transmission lines may be realized, as well as a transmission equipment used for that network and a method of control thereof. The transmission equipment comprises an APS byte transmitter/receiver for exchanging information on failures with adjacent transmission equipment through a protection line, a monitor for monitoring anomalies on a plurality of the working lines, a Network Table for storing data indicating network structure, a processing unit for determining working lines to be switched based on the data stored in the Network Table and for processing APS bytes. APS bytes are allocated with the working line number, its priority, and the source node number of switching signal. In addition a Network Table is provided to each node for storing connecting state of the network and information on failures, thereby the destination node may be identified. When a failure occurs, the best optimal line switching will be performed by exchanging information on failures by means of the APS bytes.