EAP is an authentication framework, not a specific authentication mechanism. The EAP provides some common functions and a negotiation of the desired authentication mechanism. Such mechanisms are called EAP methods and there are currently about 40 different methods. Methods defined in IETF RFCs include EAP-MD5, EAP-OTP, EAP-GTC, EAP-TLS, EAP-IKEv2, EAP-SIM, and EAP-AKA, and in addition a number of vendor specific methods and new proposals exist. Commonly used modern methods capable of operating in wireless networks include EAP-TLS, EAP-SIM, EAP-AKA, PEAP, LEAP and EAP-TTLS. Requirements for EAP methods used in wireless LAN authentication are described in RFC 4017.

When EAP is invoked by an 802.1X enabled NAS (Network Access Server) device such as an 802.11 a/b/g Wireless Access Point, modern EAP methods can provide a secure authentication mechanism and negotiate a secure PMK (Pair-wise Master Key) between the client and NAS. The PMK can then be used for the wireless encryption session which uses TKIP or AES encryption.

EAP is not a wire protocol, instead it only defines message formats. Each protocol that uses EAP defines a way to encapsulate EAP messages within that protocol's messages. In the case of 802.1X, this encapsulation is called EAPOL, " EAP over LANs".

Links

RADIUS (Remote Authentication Dial In User Service)
RFC 2865 RADIUS Standards Document