Abstract: A network optimization method measures the line bit error rate (BER) at a receiver by counting forward error correction corrected errors, and adjusts network parameters to minimize the corrected error rate. Adjustable parameters include, among other things, transmitter extinction ratio, transmitter polarization, and dispersion. The method includes sweeping an adjustable parameter while monitoring the FEC corrected bit error rates at the receiver, and then extrapolating an optimum value of the parameter. In this way, the corrected BER can be maintained below the predetermined BER limit while the digital communication network is in-service.