Patent ID: 6968102

Claim:
A node device for a bi-directional optical ring network comprising: a clockwise demultiplexing part for demultiplexing an input multiplexed wavelength signal into a clockwise active wavelength signal and a clockwise auxiliary wavelength signal; a counter clockwise demultiplexing part for demultiplexing another input multiplexed wavelength signal into a counter clockwise active wavelength signal and a counter clockwise auxiliary wavelength signal; a first switch part for transmitting the clockwise active wavelength signal and the counter clockwise auxiliary wavelength signal during a normal operation and returning the counter clockwise auxiliary signal when a fault occurs in an adjacent optical transmission path situated on a left side of the node device; a fourth switch part for transmitting the counter clockwise active wavelength signal and the clockwise auxiliary wavelength signal during the normal operation and returning the clockwise auxiliary signal when a fault occurs in an adjacent optical transmission path situated on a right side of the node device; a clockwise add/drop part for adding or dropping a predetermined wavelength signal in the clockwise active wavelength signal transmitted from the first switch part; a counter clockwise add/drop part for adding or dropping a predetermined wavelength signal in the counter clockwise active wavelength signal transmitted from the fourth switch part; a second switch part for transmitting the clockwise active wavelength signal output from the clockwise add/drop part and the counter clockwise auxiliary wavelength signal output from the counter clockwise demultiplexing part during the normal operation and returning the clockwise active wavelength signal output from the clockwise add/drop part when a fault occurs in the adjacent optical transmission path situated on the right side of the node device; a third switch part for transmitting the counter clockwise active wavelength signal output from the counter clockwise add/drop part and the clockwise auxiliary wavelength signal output from the clockwise demultiplexing part during the normal operation and returning the counter clockwise active wavelength signal output from the counter clockwise add/drop part when a fault occurs in the adjacent optical transmission path situated on the left side of the node device; a clockwise multiplexing part for multiplexing the clockwise active wavelength signal transmitted from the second switch part and the clockwise auxiliary wavelength signal transmitted from the fourth switch part; and a counter clockwise multiplexing part for multiplexing the counter clockwise active wavelength signal transmitted from the third switch part and the counter clockwise auxiliary wavelength signal transmitted from the first switch part.