A transmission apparatus includes: a switch circuit to hold a first protection path provided for a working path in a first network, a second protection path provided for the working path in a second network, and a bridge path provided between a working apparatus to relay traffic on the working path between the first and second networks and a protection apparatus to relay traffic on the first and second protection paths; and a signal processing unit to, upon reception of a first control signal indicating a failure on the working path from the first network, transmit the first control signal to the working apparatus and control the switch circuit in accordance with a second control signal corresponding to the first control signal received from the working apparatus, wherein the transmission apparatus is the protection apparatus, and is provided on a boundary between the first and second networks.