802.1X is a standard for network access control that provides an authentication mechanism to devices wishing to attach to a LAN or WLAN. It is based on the EAP (Extensible Authentication Protocol) framework for transporting authentication protocols and encapsulating the EAP within Ethernet frames. In the context of the Cisco Service Provider, implementing 802.1X can ensure that only authenticated devices are allowed access to the network, enhancing security. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco