An important issue in network management and survivability is the ability to measure the performance of the optical data, detected degradation and failure, and provisioning means of failure location and isolation. Our propose to monitor the optical performance consists in determine the statistical characteristic of an optical signal asynchronously detected and use the asynchronous electrical SNR (Q-factor) to monitor the BER, when the optical signal is significantly degraded by noise, chromatic dispersion and nonlinear effects Even in these cases a Gaussian statistics could be applied to the detected signal.