A monitoring and calibration apparatus for an optical networking device such as ROADM is provided. Reflectors are integrated into the device, for example at the ends of optical interconnect cables. The reflectors reflect light in specific monitoring wavelengths and pass other wavelengths such as those used for communication. A light source emits monitoring light which is reflected by the reflector and measured by a detector to measure the integrity of optical paths. The optical paths can include optical cables and cable connectors. Path integrity between different modules of the device can therefore be monitored. Multiple reflectors, reflecting light in different wavelengths, can be placed in series along the same optical path and used to monitor multiple segments of the path. A wavelength selective switch (WSS) of the device can be used to route monitoring light to different optical paths. The WSS also operates to route communication signals in the device.