Networks contain many networking devices like hubs, switches, routers, firewalls, wireless access points, cabling systems, workstations, servers, different software applications etc. Maintaining security with multiple devices and many different software applications is a serious issue. Every new device added or software installed may create a security hole. Network Access Control (NAC) can be defined as a method of enforcing endpoint security (Anti-virus, Anti-virus status, Host Intrusion Detection System, vulnerability assessment), user security, system authentication and network security. Two major Network Access Control (NAC) implementations are Network Access Protection (NAP) which is a Microsoft technology for controlling network access of a computer host, and Network Admission Control (NAC) is Cisco’s technology for controlling network admission.

Microsoft’s Network Access Protection (NAP) measure the connecting system’s health like anti-virus protection, anti-virus status, OS patches and updates, and system policies.

Cisco’s Network Admission Control (NAC) is available as an architecture-based framework solution designed to take advantage of an existing base of both Cisco network technologies and existing deployments of security and management solutions from other manufacturers. Cisco’s Network Admission Control (NAC) enforces policies chosen by the network administrators.