1. A method for adjustment of one or more control parameters of a section of an optical fiber network, the method comprising: taking measurements of optical signals in the section; deriving estimated data from the measurements and from knowledge of the section, where the estimated data is a function of optical nonlinearity and of amplified spontaneous emission; evaluating gradients of an objective function using the measurements and the estimated data; and applying one or more control algorithms using at least the gradients to adjust the one or more control parameters.