A method for determining whether a configuration of an optical transmission interface of a first device has to be adjusted for transmitting an optical signal to a second device via an optical band-pass filter, the second device including an optical reception interface configured to enable receiving optical signals output by the optical band-pass filter and transmitted by the first device on a carrier wavelength when the carrier wavelength is included in the passband of the optical band-pass filter. A monitoring device performs: obtaining an information representative of a signal temporal shape corresponding to a symbol of an optical signal received by the second device, from the first device, via the optical band-pass filter; determining whether the configuration of the optical transmission interface of the first device has to be adjusted, on the basis of the information representative of the signal temporal shape.