A method of routing of signals through an optical network involves determining a route through the network for which the power level within each branch of the network along the route is below a threshold power level which is a function of the fiber characteristics of the branch. This threshold power is the power below which a fiber fuse can not be initiated. This method enables power levels within a network to be controlled such that the threshold power is not exceeded, and a fiber fuse will not be initiated. The invention provides a network controller for carrying out this method.