Network Access Control, or NAC, is a security solution that controls access to your network. With Network Access Control, devices that are connected to the network are visible and access can be managed through policy enforcement on devices and users of the network. It can be used to strengthen your network security infrastructure by providing the visibility, access control, and compliance capabilities that are required.
A common use of a Network Access Control system is to deny network access to devices that don't comply with the policy, quarantined them, or give them only restricted access to computing resources. This helps prevent infected devices from affecting the rest of the network.
"Some of your users are seeing issues with 802.1x user authentication so it may be a good idea to deploy a NAC solution like Aruba Clearpass, Network Sentry, or PacketFence."