In this paper a standard bidirectional DWDM solution is taken for further research. Basing on ITU standards and available resources we have taken a real-working bidirectional 72.8 km reach DWDM system with 40 Gbit/s total capacity for further research. The system terminates four 10 Gbit/s channels and transports them through optical fiber to the total distance of 72.8 km. According to investigated DWDM system we have created a simulation scheme in OptSim software with the real parameters of all modules. In order to prove the accuracy of simulation, its results are compared with the real ones. The goal of this paper is to modify the simulation scheme and to gain results for further optimization of bidirectional DWDM solution.