Method and apparatus for detecting malfunctions in communication systems

A method for detecting a security attack in an optical network, the method comprising:

• coupling a portion of an input signal provided to an optical device of the optical network through a first signal path to a processing unit;
• coupling a portion of an output signal provided by the optical device of the optical network through a second signal path to the processing unit with the path lengths of the first and second signal paths being substantially the same;
• delaying the portion of the input signal coupled to the processing unit by an amount of time corresponding to a transmission path delay of the optical device;
• comparing the portion of the input signal provided to the optical device to a first predetermined set of parameters and comparing the portion of the output signal provided by the optical device to a second predetermined set of parameters;
• and
• in response to the input signal provided to the optical device having a first relationship to the first predetermined set of parameters, providing an indication that the network is the subject of a security attack.