In order to cater long distance optical network units (subscribers), optical networks with prolonged reach are needed. In this study, an optical back propagation (OBP) dual polarization (DP)-128 QAM-based system is proposed to cope with nonlinear impairments in wavelength division multiplexing (WDM) systems. In pre, post and symmetrical configurations, the OBP module consisting of the optical phase conjugator (OPC), Raman fiber amplifier (RFA) and erbium doped fiber amplifier (EDFAs) is examined. Using dispersion compensation fiber (DCF) as RFA with dual directional pumping, ideal OBP conditions are simulated. DP-128 quadrature amplitude modulation (QAM) system is proposed with symmetrical OBP and compared with single channel digital back propagation (DBP), wideband DBP, pre OBP-forward pumping, pre OBP with backward pumping, pre OBP with dual directional pumping, post OBP with dual directional pumping. It is observed that symmetrical OBP configuration with dual direction pumping provide enhanced results and successfully cover 6500 km at bit error rate (BER) 10−3.