Metodo para la monitorizacion de capa fisica en redes opticas pasivas, comprende: a) proporcionar reflectores opticos en diferentes puntos de una red optica pasiva o pon,b) inyectar una señal luminosa de monitorizacion en una entrada de dicha pon para que circule por la misma, c) reflejar de vuelta, dichos reflectores opticos, d) recibir dichas señales luminosas, e)analizar dichas señales, dicha etapa a) comprende proporcionar dichos reflectores opticos dentro de la red exterior de la pon; siste

A method and a system for physical layer monitoring in Passive Optical Networks. The system comprises: -a light source (2) injecting a varying wavelength monitoring light signal at an input of a PON; -optical reflectors (8) provided at different points of said PON for receiving the monitoring light signal and reflecting back, each, that part of said monitoring light signal having a specific and individualized wavelength; -light detecting means (17) arranged for receiving said reflected light signals; and -analysis means connected to said light detecting means (17) and with access to previous knowledge about which specific wavelength each reflector (8) reflects, to determine the location of each of the optical reflectors (8) as a function of the arrival order, at said light detecting means (17), of its respective reflected signal. The method is adapted to use the system for physical layer monitoring in PONs.