VLANs are the foundation of every switched network. Layer 2 design decisions made here ripple through your entire infrastructure. This series covers everything from what a VLAN actually is to advanced campus design, Private VLANs, EtherChannel, and inter-VLAN routing on both routers and Layer 3 switches.
Every article is written for network engineers working with Cisco Catalyst switches on IOS XE. Real configs, real show commands, real troubleshooting scenarios.
🧱 Start Here - VLAN Fundamentals
Build your foundation. These articles explain what VLANs are, how frames get tagged, and the core switching concepts behind every VLAN deployment.
- What Is a VLAN? Virtual LANs Explained for Network Engineers
- How VLANs Work: Tagging, Broadcast Domains, and Frame Forwarding
- VLAN Access Ports and Switchport Modes: Access, Trunk, and Dynamic
- VLAN Trunking Explained: 802.1Q, Allowed Lists, and Trunk Negotiation
- DTP (Dynamic Trunking Protocol): How It Works and Why You Should Disable It
⚙️ VLAN Configuration
Hands-on Cisco switch configuration for VLANs, trunks, native VLAN security, and VTP. The articles every network engineer needs before touching a production switch.
- Configuring VLANs on Cisco Catalyst Switches
- VLAN Naming, Ranges, and Management Best Practices on Cisco IOS XE
- Configuring 802.1Q Trunks on Cisco Catalyst Switches
- Native VLAN Configuration and Security on Cisco Switches
- VTP Configuration on Cisco Switches: Versions 1, 2, and 3
🌐 SVIs & Inter-VLAN Routing
How to route between VLANs using Switch Virtual Interfaces, a router-on-a-stick, or a fully routed Layer 3 switch. Understand the trade-offs before you choose an approach.
- Configuring SVIs (Switch Virtual Interfaces) for Inter-VLAN Routing
- Inter-VLAN Routing with Router-on-a-Stick on Cisco IOS XE
- Inter-VLAN Routing on a Layer 3 Switch: SVI-Based Routing on Catalyst 9000
🎯 Specialized VLANs
Beyond standard data VLANs. Voice VLANs for IP phones and Private VLANs for traffic isolation within a segment.
- Configuring Voice VLANs on Cisco Switches for IP Phones
- Private VLANs on Cisco Catalyst Switches: Isolated and Community Ports
🔗 EtherChannel & Link Aggregation
Bundle physical links into logical port channels for redundancy and increased throughput. Covers PAgP, LACP, load balancing, and how EtherChannel interacts with Spanning Tree.
- EtherChannel Fundamentals: Link Aggregation, PAgP vs LACP, and Load Balancing
- Configuring EtherChannel with LACP on Cisco Catalyst Switches
🔧 Troubleshooting
When VLANs stop working, these articles help you isolate the problem fast. Whether it is a misconfigured trunk, a missing SVI, or an ARP issue blocking inter-VLAN traffic.
- Troubleshooting VLAN and Trunk Problems on Cisco Switches
- Troubleshooting Inter-VLAN Routing: SVIs, Router-on-a-Stick, and ARP Issues
- Troubleshooting SVI Up/Down Issues on Cisco Catalyst Switches
🏗️ Design & Security
Put it all together. These articles cover Layer 2 security hardening and VLAN design for multi-tier campus networks, from access layer to core.