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Difficulty: MediumAAA Framework and Authentication Methods

An enterprise security team is deploying 802.1X port-based network access control across corporate network switches. In this architecture, the edge switch serves as the authenticator and relays Extensible Authentication Protocol (EAP) messages between the client host and a centralized authentication server. Which protocol is primarily utilized between the switch and the authentication server to transport these encapsulated EAP packets?

  1. RADIUSAnswer
  2. B
    TACACS+
  3. C
    Kerberos
  4. D
    LDAP

Answer

RADIUS is the standard protocol used by the network switch to encapsulate and relay 802.1X EAP authentication traffic to the central AAA server.
In an 802.1X framework, the supplicant (client) communicates with the authenticator (switch) using EAPoL (EAP over LAN). The authenticator then re-encapsulates these EAP messages into RADIUS packets (over UDP ports 1812/1813) to communicate with the backend AAA server.

Step-by-Step Solution

1
Identify the role of the network switch in the 802.1X architecture.
The switch acts as the Authenticator, bridging client EAP over LAN (EAPoL) traffic to the backend server.
The switch does not make the final authentication decision; it relays credentials securely to the AAA server.
2
Determine the backend protocol capable of encapsulating EAP messages.
RADIUS natively supports EAP encapsulation (RADIUS attributes carry EAP packets over UDP).
802.1X explicitly defines RADIUS as the primary protocol for carrying EAP payloads from authenticators to authentication servers.

Key Concept

802.1X EAP Protocol Encapsulation via RADIUS
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Topics

AAA Framework and Authentication Methods

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