Why use port or user-based access control?

Local Area Networks are often deployed in a way that allows unauthorized clients to attach to network devices, or allows unauthorized users to get access to unattended clients on a network. Also, the use of DHCP services and zero configuration make access to networking services easily available. This exposes the network to unauthorized use and malicious attacks. While access to the network should be made easy, uncontrolled and unauthorized access is usually not desirable. 802.1X simplifies security management by providing access control along with the ability to control user profiles from up to three RADIUS servers while allowing a given user to use the same entering valid user credentials for access from multiple points within the network.