The importance of a network security to protect infringement of corporate assets has been issued due to the increasing various threats such as warm virus, vicious codes, and hacking. Thus, the goal of this research is to discover the procedure and methods for a NAC system implementation. In this case study, we suggest that the critical management issues during the implementing a NAC system as well as measure its performance in qualitative and quantitative perspective. The contribution of this paper is both to lead to the further research in this network security field and to provide a guideline for companies willing to introduce a NAC system.