VLAN Topology Design

You will design a VLAN topology with an addressing plan, trunking, and inter-VLAN routing, then build and validate it. By the end you will have a documented, segmented network with verified connectivity per design.

Learning Objectives

Produce a VLAN and addressing plan.
Configure access ports, trunks, and inter-VLAN routing.
Validate the build against the design.
Time: ~8 hours · Difficulty: Intermediate · Prereqs: the VLAN and routing labs.

Architecture Overview

graph TD R[L3 switch / router] --> V10[VLAN 10 - 10.0.10.0/24] R --> V20[VLAN 20 - 10.0.20.0/24] R --> V30[VLAN 30 - 10.0.30.0/24] SW[Access switch] -->|802.1Q trunk| R

Environment Setup

A managed switch and an L3 device (or emulator).
An addressing plan with one subnet per VLAN.
An inter-VLAN access policy.

Step-by-Step Execution

Define VLANs and access ports

vlan 10,20,30 ; interface Gi0/2 ; switchport mode access ; switchport access vlan 20

Configure the trunk and SVIs

interface Gi0/1 ; switchport mode trunk ; switchport trunk allowed vlan 10,20,30

Verify VLAN assignments

# show vlan brief

VLAN Name Status Ports 20 PROD active Gi0/2 30 GUEST active Gi0/3

Progress So Far

graph LR A[01 VLANs + access] -->|done| B[02 Trunk + SVIs] B -->|done| C[03 Verify] style A fill:#1a4a1a,stroke:#00ff00,color:#fff style B fill:#1a4a1a,stroke:#00ff00,color:#fff style C fill:#1a4a1a,stroke:#00ff00,color:#fff

Testing & Validation

ping -c2 10.0.20.1 && ping -c2 10.0.30.1

Hosts should reach their gateway and approved VLANs while denied paths fail. Confirm the trunk carries all VLAN IDs and the build matches the design document.

Troubleshooting

VLAN not passing the trunk: add the VLAN ID to the allowed list on both ends.
No inter-VLAN routing: enable routing and verify SVIs are up.
Native VLAN mismatch: align native VLANs to prevent tag leakage.

Extension Ideas

Add ACLs between VLANs (see Access Control Lists).
Build the full version in Complete Network Implementation.
Add redundancy with STP/LACP.

Key Results

Produced a VLAN and addressing design, then built it.
Configured access ports, a trunk, and inter-VLAN routing.
Verified connectivity and isolation against the design.
Documented the topology for handover.

VLAN Topology Design and Build