US Patent 8005357 Optical transmission apparatus

An optical transmission apparatus includes redundant line cards each installed with hardware and a CPU. The hardware obtains failure information on redundant lines including a working line and a protection line, and the CPU determines switching control of the redundant lines based on the obtained failure information. Further, the hardware switches the redundant lines based on switching control determined by the CPU, so as to transmit an SDH/SONET optical signal. In the apparatus, from or to hardware installed in each of the redundant line cards, the failure information obtained by the hardware is communicated to hardware installed in a neighboring line card.