With increasing demand for high capacity mobile data services and a simultaneous decline in revenue per bit, network operators face the challenge of providing high capacity while reducing overall network costs. A key aspect within Passive Optical Networks is the implementation of simple monitoring strategy on the physical layer which gives the possibility for the operator to save a signicant amount of operation and maintenance expenses (OpEx). In this framework, we propose an emerging and promising technique, i.e. Optical Frequency Domain Reflectometry, in order to localize any kind of deterioration in the optical distribution network (ODN) that may cause suspended services. Unlike the conventional optical time-domain reflectometry (OTDR), the proposed technique is intrinsically characterized by high-spatial resolution and high sensitivity.