OSPF Design Best Practices for Enterprise Networks
Real OSPF design rules: keep Area 0 stable and small, cap routers per area, use stub where you can, and make summarization a feature of your area boundaries.
Latest posts — page 49
Understanding RADIUS in 802.1X Authentication
RADIUS is the glue between a Catalyst switch and Cisco ISE in 802.1X. Here is how the Access-Request carries EAP, why UDP 1812/1813 matters, and where failures surface.
EAPOL Explained: How 802.1X Traffic Moves Over the Wire
EAPOL carries EAP between the supplicant and switch at Layer 2. It never leaves the segment, which is why captures and debug have to happen on or at the port.
How EAP Works in 802.1X: EAP Methods Compared
EAP is a framework, not a protocol. Compare EAP-TLS, PEAP-MSCHAPv2, EAP-FAST, and EAP-TTLS by credential type, tunnel, and where each belongs in enterprise 802.1X.
802.1X Components Explained: Supplicant, Authenticator, and Authentication Server
802.1X splits work across three roles: supplicant, authenticator, and authentication server. Understanding the boundaries explains both the config and the failure points.
What Is 802.1X? Port-Based Network Access Control Explained
802.1X is port-based network access control. It forces a device to authenticate before the switch forwards traffic, closing the wall-jack gap in modern enterprise networks.
MAC Authentication Bypass (MAB) Configuration on Cisco IOS XE and ISE
MAB authenticates printers, cameras, and legacy gear that cannot run a supplicant by using their MAC as the RADIUS username. Here is the Cisco IOS XE and ISE config.
Configuring EAP-TLS with Certificates on Cisco ISE and IOS XE
EAP-TLS replaces 802.1X passwords with mutual certificate auth. Here is the PKI prep, ISE policy, and IOS XE config you need for a production certificate-based rollout.
Configuring PEAP Authentication with Cisco ISE and IOS XE
PEAP-MSCHAPv2 protects the credential exchange inside a TLS tunnel against an ISE server certificate. Here is the full Cisco ISE and IOS XE config for AD users.
Configuring Cisco ISE as a RADIUS Server for 802.1X
The ISE side of 802.1X: network devices, identity sources, authentication and authorization policies, and the Policy Set that ties it all together for a Catalyst 9300.
Basic 802.1X Port Configuration on Cisco IOS XE Switches
A complete 802.1X switchport config on IOS XE 17.9: AAA, RADIUS servers, dot1x system-auth-control, interface policy-map, and the voice VLAN gotchas to avoid.
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.