Welcome back! In the previous guide, Subnetting and IP Planning, we laid the groundwork for organizing your IP space. Whether you’re running a few devices or a growing homelab, subnetting gives you structure. It defines boundaries — but it doesn’t control how devices actually talk to each other.

That’s where VLANs step in.

Virtual Local Area Networks (VLANs) allow you to segment your network traffic logically — without needing extra physical switches or separate cables. You can separate your smart home gear from your workbench machines, carve out a guest network, or wall off your NAS — all using the same physical gear you already own. VLANs let you define traffic lanes and apply rules to how devices share the road.

VLANs let you group and govern devices by purpose — whether that’s shielding sensitive traffic, optimizing performance, or enforcing access boundaries — all without running extra cable.

In this guide, we’ll walk through the concepts, benefits, and configurations of VLANs. You’ll learn how they work on switches, how to route between them, and how to plan your segments based on real-world use. If you’re running virtual environments or firewalls like pfSense, this is where your network starts to feel serious — and secure.

Let’s build on your IP planning knowledge and dive into VLANs: one of the most useful (and underused) tools in a homelabber’s toolkit.

What Are VLANs?

A VLAN (Virtual Local Area Network) is a way to logically separate network traffic over a shared physical infrastructure. Instead of relying on separate switches or patch panels, VLANs use IEEE 802.1Q tagging to distinguish traffic and keep devices in their own virtual lanes.

Each VLAN gets a unique ID (between 1 and 4094, though VLAN 1 is often reserved for default management and best avoided in custom setups). These IDs tell switches how to isolate broadcast domains, which devices belong to which segment, and how traffic should flow.

You can think of VLANs like separate rooms in the same building — walls without needing extra floors. They keep noise down and let you control who has a key.

Comparing VLANs vs. Physical LAN Segments

So when should you use VLANs, and when should you just plug into a different switch?

• Physical segmentation is simple and often more secure. You know if two devices aren’t on the same cable path, they’re isolated. But it scales poorly and burns ports and gear fast.

• VLANs let you be precise. You can run multiple logical networks over the same port using tagging, which saves money and makes reconfiguration easier. But they introduce complexity — one misstep in tagging or firewall rules can expose traffic or cause mysterious outages.

In practice, many homelabs use a mix: physical separation for infrastructure, VLANs for flexibility.

Related reading: Ports for Everyone

Planning Traffic Segmentation

VLANs let you design your network around how you use it. Here are some common reasons to segment traffic:

• IoT devices often have poor security and shouldn’t access the rest of your network.
• Guest networks can provide internet access without exposing your lab or files.
• Experimental hardware like Raspberry Pis, dev boards, or VMs can break things — keep them isolated.
• VoIP phones or SIP gateways benefit from dedicated VLANs to prioritize traffic and improve call quality.
• Production vs. lab environments can be separated cleanly without duplicating hardware.
• Security zones (like isolating your NAS or backups) reduce the risk of accidental or malicious cross-traffic.
• Critical infrastructure (routers, VPN servers, internal DNS) can live in their own high-trust VLAN.

Pro tip: Give each VLAN a clear name and purpose. That makes firewall rules easier to reason about later — and future-you will thank you.

Pro tip: Some wireless access points support VLAN tagging per SSID — a great way to assign guest, IoT, or trusted devices to separate segments. See your AP’s docs for VLAN or multiple SSID support.

Related reading: Planning and Documenting Your Homelab Network

Configuring VLANs on Your Switch

VLAN support varies, but most managed switches support it through web interfaces or CLI.

• Access ports connect directly to a device and carry untagged traffic for a single VLAN.
• Trunk ports carry traffic for multiple VLANs. Each packet is tagged so the receiving end can sort it.

When setting up:

• Assign each switch port as either access or trunk.
• Tag trunk links consistently between switches and routers.
• Make sure untagged (native) VLANs are set correctly to avoid leaks.

This is where most mistakes happen — document your plan and test each step as you go.

When connecting a VLAN-aware device (like a server or firewall) directly to a trunk port, make sure it’s configured to tag traffic properly — unmanaged devices won’t understand VLAN tags and may lose connectivity.

VLANs on Routers and Firewalls

Switches isolate traffic, but routers and firewalls control how VLANs talk to each other.

With platforms like pfSense, OPNsense, or OpenWRT, you can:

• Create VLAN interfaces bound to a physical port (e.g., em0.10 or eth0.10 for VLAN 10).
• Assign those VLANs to internal firewall zones or interfaces.
• Enable DHCP services or assign static IPs per VLAN.
• Define firewall rules to allow or block inter-VLAN traffic.
• Tag multiple VLANs on a single physical port for trunking to a managed switch.

pfSense and OPNsense

Both pfSense and OPNsense offer robust VLAN support and intuitive interfaces for managing them. VLANs are typically configured under Interfaces > Assignments, where you can create new VLAN interfaces and attach them to physical NICs.

Once defined, each VLAN interface behaves like a separate network:

• You can apply DHCP, DNS, and gateway settings per VLAN.
• Inter-VLAN routing is enabled by default, but firewall rules give you precise control.
• Assign VLANs to interfaces and write rules in Firewall > Rules to restrict or allow communication between networks.

These platforms also support advanced setups — like routing VLANs through VPN tunnels, applying traffic shaping, and integrating with IDS/IPS systems per VLAN.

OpenWRT

OpenWRT provides full VLAN support via its web UI (LuCI) or CLI (uci or /etc/config/network). It’s especially useful on consumer-grade routers, allowing logical segmentation even with limited physical ports.

Key features include:

• Assigning VLAN tags to physical interfaces using the built-in switch configuration.
• Tagging the CPU (internal) port correctly so VLAN traffic reaches the firewall.
• Creating per-VLAN DHCP, DNS, and firewall rules via LuCI or /etc/config/firewall.

OpenWRT can trunk VLANs over LAN or WAN ports, enabling flexible and advanced deployments for ISPs, guest networks, or homelab segmentation.

Pro tip: Always confirm the tagging scheme on OpenWRT matches your managed switch setup — mismatches are a common cause of VLAN issues.

Related reading: Configuring Wireless Networks and Firewalls

VLANs in Virtual Environments

Virtual machines and containers often need network isolation too — VLANs can extend here as well.

Platforms like Proxmox, KVM, or VMware support virtual NICs and bridges that pass VLAN tags:

• Set your virtual switch or bridge to trunk mode.
• Tag each VM’s virtual NIC with the right VLAN.
• You can even isolate container networks this way, or combine virtual and physical networks seamlessly.

On platforms like ESXi, you may need to allow trunking (e.g., setting VLAN ID to 4095) to pass tags into nested VMs — double-check your hypervisor’s VLAN handling.

Related reading: Essential Linux Commands

Common Mistakes and Troubleshooting

Even a simple VLAN setup can go sideways if you miss a detail.

Here are common pitfalls:

• Mismatched tagging: If one switch tags a VLAN and the next doesn’t expect it, traffic disappears.
• Native VLAN confusion: Unclear use of native VLANs (untagged traffic) causes ghost behavior.
• Firewall gaps: Rules that are too open or too strict can block traffic or expose devices.
• MTU problems: VLAN tags add bytes; if a device expects a standard 1500 MTU, you may see drops.
• Tool blindness: Use tcpdump, bridge vlan, or switch logs to confirm tagging and flow.

Related reading: Introduction to Networking for the Homelab

Conclusion

VLANs give your homelab structure and security — without requiring a rack full of switches. With just a few config steps, you can isolate guests, control broadcast traffic, and scale cleanly as your environment grows.

As you become more confident with VLANs, you’ll spot opportunities to segment traffic, lock down services, and optimize performance.

Need a refresher on IP layouts or subnet ranges? Head back to Subnetting and IP Planning for a quick recap.