In this paper, the performance of high speed optical fiber based network is analysed by using dispersion compensating module (DCM). The optimal operating condition of the DCM is obtained by considering dispersion management configurations for the symmetrical system i.e Pre-compensation & Post-compensation. The dispersion compensating fiber (DCF) is tested for a single span, single channel system operating at a speed of 10 Gb/s with a transmitting wavelength of 1550 nm, over 120 km single mode fibre by using the compensating fiber for 24 km,30km and 35Km. So far, most of the investigations for single mode fiber (SMF) transmission at high amplifier spacings in the order of 90 km to 120 km is focused on conventional Non Return to Zero(NRZ) format. The simulation results are validated by analysing the Q-factor and Bit error rate (BER) in the numerical simulator OptSim.