802.1X

Port-based network access control, the standard for authenticating users and devices onto wired and wireless networks. Articles tagged 802.1X cover supplicant and authenticator behavior, RADIUS, EAP methods, Cisco ISE, dynamic VLANs, dACLs, host modes, and phased deployment.

33 posts

802.1X

802.1X Authentication Flow Step by Step: From EAPOL Start to RADIUS Accept

The 802.1X authentication flow, step by step, from EAPOL-Start through RADIUS Access-Accept and port authorization. Three conversations, one timeline, no magic.

Mar 24, 2026 7 min read

802.1X

Introduction to Cisco ISE: What It Is and Why It Matters for 802.1X

Cisco ISE is more than a RADIUS server. It is the policy decision point for 802.1X, layering device type, posture, and context on top of pass/fail authentication.

Mar 24, 2026 10 min read

802.1X

Change of Authorization (CoA) in 802.1X: How It Works and How to Configure It

RADIUS CoA lets ISE push policy updates to the switch mid-session, no re-auth required. Here is the IOS XE and ISE config, plus the posture remediation use case.

Mar 24, 2026 11 min read

802.1X

Web Authentication as a Fallback in 802.1X: Configuration and Use Cases

Web authentication adds a captive portal as an 802.1X fallback for guests, contractors, and unmanaged endpoints. Here is the Cisco IOS XE and ISE config.

Mar 24, 2026 11 min read

802.1X

802.1X with IP Phones: Configuring Multi-Domain Authentication on Cisco IOS XE

Multi-domain authentication lets an IP phone and a PC share one 802.1X port with separate voice and data VLANs. Here is the Cisco IOS XE config and verification.

Mar 24, 2026 11 min read

802.1X

Downloadable ACLs (dACLs) with Cisco ISE and 802.1X

dACLs move ACL definitions off the switch and into ISE, delivered per session via RADIUS. Here is how the download mechanism works and how to configure both sides.

Mar 24, 2026 10 min read