Wireless communications are constantly evolving to facilitate better access to information for the improvement of business, education, and technology around the world. Hence to overcome the lack of spectrum new bands like millimeter wave (mmWave) bands are needed to be utilized. The mmWave bands offer a huge spectrum due to which substantial attention is being given to exploit this frequency range for deploying 5G cellular systems. 5G wireless technology is expected to deliver multi-Gbps data rates, vast network capacity, low latency, and more reliability. Despite the provision of the spectrum, the new mmWave bands are prone to blockages and obstacles. Hence, these bands must be deployed with the help of an architecture that can overcome this drawback and can prevent any disruption of service in case of blockage. This paper implements a non-standalone (NSA) architecture using modified dual connectivity of user equipment (UE) to Long Term Evolution (LTE) module and mmWave module of ns-3 for more robust deployment of 5G New Radio (NR) network. It also includes a detailed discussion upon the design and functioning of 5G NR in NSA mode with the help of a simulation setup. Finally, the performance of the 5G network in standalone (SA) and non-standalone modes are compared both graphically and numerically based on the throughput measurements.