Abstract: A method and apparatus for identifying at least one characteristic of at least one optical link of an optical network. The method comprises modulating a predetermined optical channel with a predetermined frequency component, and transmitting the modulated predetermined optical channel onto an optical waveguide at a predetermined power such that at least one optical data channel co-propagating along the optical waveguide with the modulated predetermined optical channel is modulated with the predetermined frequency component.

Abstract: A component for an optical communication network comprises a source (6) for an optical communication signal, an output port (11) for outputting the optical communication signal on an optical transmitting fiber (1), a light sensor (14; 15) and an optical circulator (9) for transmitting the optical communication signal from the source (6) to the output port (11) and for transmitting light reflected or received from outside at the output port (11) to the light sensor (14; 15). The light sensor (14, 15) has an evaluation circuit (13) connected to it for detecting a time delay between a time marker of a light signal from the source and the corresponding time marker of the light arriving at the light sensor (14; 15).