STP and EtherChannel: When They Collide and Who Wins
How EtherChannel hides bundled links from STP, the bundling protocols (LACP, PAgP, on), the dangerous failure modes, and why LACP active on both sides is the only safe configuration.
Fundamentals
Networking fundamentals and CCNA-level reference content. The TCP/IP and OSI models, ethernet basics, encapsulation, IPv4 addressing, layer 2 fundamentals, and the Cisco IOS commands every network engineer reaches for. The foundations beneath the pillar guides.
Latest posts — page 5
Inter-VLAN Routing: SVI vs Router-on-a-Stick (with Real IOS XE Config)
The two ways to route between VLANs on Cisco: SVIs on an L3 switch and router-on-a-stick. Real IOS XE config for both, the performance gap, and the gotchas.
MPLS L3VPN vs SD-WAN: When to Migrate
A decision framework for migrating from MPLS L3VPN to SD-WAN: what's different, when to migrate, the 7-step transition that works, and when the right answer is to stay.
BGP Looking Glass: What It Is, Public Servers, and Hosting Your Own
BGP looking glasses explained: what they show, the public servers worth bookmarking, a four-step troubleshooting recipe, and how to host your own with hyperglass.
VLAN, Subnet, and Broadcast Domain: What's the Difference?
VLAN, subnet, and broadcast domain are not the same thing. The layer each lives at, the relationships between them, and the misalignment that breaks hosts silently.
SD-WAN: What Is It? The 5-Minute Primer
SD-WAN in five minutes: what it is, what it replaces, the four-plane architecture, transport-independent overlays, and how it stacks against traditional MPLS WANs.
Enable IEEE 802.1X Authentication on Windows 11 (Manual + Group Policy)
How to enable IEEE 802.1X on Windows 11 wired adapters. Start the Wired AutoConfig service, configure the Authentication tab, push the same settings via Group Policy.
What is 802.1X Authentication? End-to-End Flow with Real show Output
How 802.1X authenticates a switch port from link-up to traffic flow. The three roles, EAPoL exchange, IOS XE config, host modes, and real show authentication sessions output.
OSPF vs BGP Redistribution: Which Protocol Wins Which Tie
When OSPF and BGP both know about the same prefix, who wins? A practical walkthrough of mutual redistribution, the admin-distance trap, and why BGP into OSPF needs a filter or it takes down your domain.
Cisco ASA Multiple Context Mode
Multiple context mode turns one Cisco ASA into several virtual firewalls, each with its own config, interfaces, ACLs, NAT, and admins. Covers the system, admin, and user-context split, what the feature costs, and the configuration to enable it.
Cisco ASA Inspection Engines: MPF and Custom Maps
The ASA Modular Policy Framework binds inspection engines to traffic with class-maps, policy-maps, and service-policies. Walk the default global policy every ASA ships with, then add custom HTTP, FTP, or ESMTP inspection without breaking it.
Cisco ASA Syslog Configuration and Logging Levels
Six lines of config give the ASA sane production syslog. This article walks the destinations, the eight severity levels, message lists for filtering, and reading the %ASA-X-XXXXXX format using real lab logs from IKEv2 failures and ACL denies.