Which IEEE standard permits or denies network connectivity based on user or device identity?

IEEE 802.1X is the standard for Port-Based Network Access Control (PNAC). It provides an authentication framework that allows a user or device to be authenticated before being granted network access. This standard is crucial for securing wired and wireless networks by preventing unauthorized access. When a device connects to a port, 802.1X uses an authenticator (like a switch) to communicate with an authentication server (like RADIUS) to verify the supplicant's (user/device) credentials. If authentication is successful, the port is opened for network traffic; otherwise, access is denied or restricted. 802.1D is the Spanning Tree Protocol (STP) for preventing loops in bridged networks. 802.1W is Rapid Spanning Tree Protocol (RSTP), a faster convergence version of STP. 802.1Q is the standard for VLAN tagging on Ethernet frames. These standards do not deal with user or device authentication for network access.