ontrol mechanism that defines the following three components (Figure 6.1): - the supplicant is the device (network host) wishing to access the Ethernet or Wi-Fi network; - the authenticator is the device (Ethernet switch or Wi-Fi access point) that controls the supplicant's access to the LAN; Wi-Fi Integration to the 4G Mobile Network, First Edition. André Perez. C ISTE Ltd 2018. Published by ISTE Ltd and John Wiley & Sons, Inc. Wi-Fi Integration to the 4G Mobile Network - the authentication server is the device that authenticates the supplicant and authorizes access to the LAN. The 802.1x mechanism relies on the following set of protocols (Figure 6.2): - the extensible authentication protocol (EAP) over LAN (EAPOL), exchanged between the supplicant and the authenticator; - the EAP exchanged between the supplicant, on the one hand, and the authenticator or authentication server, on the other hand: - the EAP is carried by the EAPOL protocol on the interface between the supplicant and the authenticator; - the EAP carries EAP-Method messages exchanged between the supplicant and the authentication server; - the remote authentication dial-in user service (RADIUS) protocol, exchanged between the authenticator and the authentication server. The RADIUS protocol carries the EAP on the interface between the authenticator and the authentication server. EAP-Method EAP-Method Other attributes Messages RADIUS EAPOL Layer 2 WiFi (MAC) Ethernet (MAC) Layer 1 WiFi (Layer 1) Eth (Layer 1) Interface between Interface between authenticator and authenticator and authentication server supplicant Figure 6.2. Protocol architecture for 802. 1x mechanism Mutual Authentication 6.1.1. EAPOL protocol The EAPOL protocol is exchanged between the supplicant and the authenticator. It initiates the supplicant's identity announcement and the capacities of each end. It ensures the transport of EAP/EAP-Method messages, which enable authentication of the supplicant, and possibly of the authentication server. The structure of the EAPOL protocol is sho