Patent ID: 7031606

Claim:
A method for monitoring performance of an optical network, comprising the steps of: (a) intensity modulating each optical wavelength channel of a multi-channel optical signal, traveling through a section of a fiber between two nodes in the optical network, with the same fiber identification (FID) tone, which is a low frequency dither tone whose frequency is unique to the fiber section; (b) measuring a power level of the FID tone at various locations in the optical network; (c) indicating the possibility of one or more of the following: (i) the fiber section failure if the FID tone is not present; (ii) an amplifier failure in the optical network if combined power levels of different FID tones at different dither tone frequencies decrease substantially uniformly; (iii) a transponder failure if the power level of the FID tone decreases provided that no optical wavelength channels are being dropped from the respective network node; and (iv) adding or dropping optical wavelength channels to the fiber section if the power level of the FID tone changes; and (d) visualizing an approximate traffic load through different fiber sections in the optical network by comparatively displaying power levels of FID tones at different FID tone frequencies, thus indicating that fiber sections having higher power levels of the FID tones carry larger numbers of optical wavelength channels.