What access control behavior does MAC Authentication Bypass (MAB) provide?

MAC Authentication Bypass (MAB) is a method where network access is granted based on a device's MAC address, rather than requiring user credentials. This is useful for devices that cannot perform 802.1X authentication, such as printers, IP phones, or legacy IoT devices. The network access device (e.g., a switch) sends the device's MAC address to an authentication server (like Cisco ISE), which then checks if the MAC address is registered and authorized. If it is, the device is granted access, often to a specific VLAN or with particular policies. Simultaneous user and device authentication is typically handled by 802.1X with multiple authentication methods, not MAB alone. MAB does not allow devices to bypass authentication entirely; instead, it uses the MAC address as the authentication credential. User access based on IP address is generally less secure and not the primary mechanism for MAB.