Patent ID: 6525852
Filing Date: 2003-02-25
Classification: H04B,H04J,H04Q

Abstract:
A node arranged to be connected in a network and for communication only with adjacent nodes, the network including a ring configuration including two optical fibers each carrying light signals in one direction, the direction being opposite each other and links connecting adjacent nodes, an inactive link carrying no light signals such that when the inactive link is made active another one of the links is made inactive, and the network carrying the light signals in a plurality of wavelength bands separate from each other, the node comprising:a drop coupler and an add coupler for each of the opposite directions for taking out a share of the light signals at the node and adding light signals in the node to the light signals carried in the network, respectively; plural receivers for receiving light signals in wavelength bands in the node and transmitters for transmitting light signals in wavelength bands from the node into the network; a band blocking filter arranged between the drop coupler and the add coupler for each of the opposite directions for blocking in the respective opposite direction light of all wavelengths in the wavelength bands of light signals which are received by the receivers in the node from the respective direction; and at least one of: a 2x1 switch coupled between the drop couplers and at least one of the receivers for allowing the at least one of the receivers to receive from either one of the opposite directions, and a 1x2 switch coupled between at least one of the transmitters and the add couplers for allowing the at least one of the transmitters to transmit in either one of the opposite directions.