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.

36 posts

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

802.1X

Guest VLAN, Auth-Fail VLAN, and Critical VLAN in 802.1X: When and How to Use Them

Guest VLAN, Auth-Fail VLAN, and Critical VLAN cover the three 802.1X failure paths: no supplicant, wrong credentials, and RADIUS down. Here is when and how to use each.

Mar 24, 2026 11 min read

802.1X

Dynamic VLAN Assignment with 802.1X and Cisco ISE

Dynamic VLAN assignment returns the target VLAN in RADIUS Tunnel attributes, so identity (not cabling) decides the network segment. Here is the ISE and IOS XE config.

Mar 24, 2026 9 min read

802.1X

802.1X Authentication Host Modes: Single-Host, Multi-Host, Multi-Domain, Multi-Auth

Single-host, multi-host, multi-domain, and multi-auth control how many MACs can use an 802.1X port. Pick the wrong mode and you get silent failures or open ports.

Mar 24, 2026 9 min read