Network Admission Control
Network Admission Control (NAC) refers to Cisco's version of network access control, which restricts access to the network based on identity or security posture. When a network device (switch, router, wireless access point, DHCP server, etc.) is configured for NAC, it can force user or machine authentication prior to granting access to the network.
Source: Wikipedia — Network Admission Control (CC BY-SA 4.0)