802.1X Network Access Control
Switching
Overview
802.1X separates a supplicant, an authenticator and an authentication server such as RADIUS. The controlled port restricts normal data until authorization succeeds. EAP identity alone is not access approval. Failure policies and exceptions need deliberate least-privilege design.
Protocol stages
- 1Supplicant
- 2Authenticator
- 3RADIUS / EAP
- 4Authorization
- 5Controlled port
Interactive exercise
Knowledge check
The RADIUS server rejects the device. In a fail-closed configuration, what happens?
Educational model — not real hardware, traffic or official certification.