A WDM optical cross-connect has input and output channels for through traffic. A first group of matrices connects the input channels to the output channels. Each input channel is connected to an input of a matrix of the first group and each output channel is connected to an output of the matrix. Input/output channels are provided for adding/dropping traffic. Each add/drop channel is connected to an input/output of a second group of matrices. The outputs/inputs of the second group of matrices are connected to inputs of a third group of matrices or outputs of a fourth group of matrices and the outputs/inputs of the third/fourth group of matrices are connected to inputs/outputs of the first group of matrices such that the matrices of the second, third and first groups of the first, fourth and second groups each form a Clos network.
展开▼