A wavelength selective switch (WSS), reconfigurable optical add-drop multiplexer (ROADM) and methods of determining a condition of a domain network section are provided. The WSS and ROADM include a light source for sending an optical signal having a characteristic. The method comprises instructing a light source to send an optical signal across an optical link, obtaining measurements of characteristic values of the optical signal received at and sent by components along the domain network section, comparing the characteristic values to pre-defined limits, and determining the condition of the domain network section based on the characteristic values.