District heating networks (DHNs) are a viable way to cut CO2 emissions. Consequently, industries and academia are both working towards new possibilities in the DHNs, from adaptation to renewable sources to the inclusion of heat pumps, etc. Nonetheless, because of the high investment costs, there is a lot of interest in simulation and software solutions to test the system beforehand. Various areas of focus are minimizing distribution losses, reducing the misuse of peak production, and maximizing the usage of storage capacities. Thus, any investigation that can help in improving the efficacy of DHNs becomes important. Hence, this paper covers a brief review of modeling research that concentrates on pipe objects or routing models, which is the most important component of DHNs. Also, various software tools are investigated that can be used to model the pipe object or whole DHN.