> ## Documentation Index
> Fetch the complete documentation index at: https://rackdog.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# VLANs

> Create private Layer 2 networks between your servers

VLANs let you build a private Layer 2 network between your servers over their secondary (non-public) network interfaces. Servers on the same VLAN can talk to each other directly, without the traffic ever touching the public internet.

## How it works

VLANs are defined logically first and only materialize on the network when they're actually needed:

1. You create a VLAN (via the API or dashboard).
2. You attach servers to it.
3. Once **two or more** servers are attached, Rackdog allocates a real VLAN on the switch and connects the servers to it.
4. The servers can now reach each other over their private interfaces.

A VLAN with a single server attached exists in your account but has no underlying network: there's no one to talk to, so nothing gets provisioned on the switch until a second server joins.

## Lifecycle behavior

* **Server removal.** Deleting a server automatically detaches it from any VLAN.
* **Down to one server.** The VLAN stays allocated internally, but there's no connectivity until another server joins.
* **Down to zero servers.** The underlying network is cleaned up. The VLAN still exists from your perspective and can be reused when you attach servers again.

## Creating a VLAN

VLANs are managed through the API today: create the VLAN, attach servers, and manage membership there. Dashboard support is on the way.

Not every server supports VLAN networking. Use the API to list VLAN-capable servers before attaching.

## Private networking

VLAN traffic flows over each server's secondary network interface. The primary interface handles public networking and is not used for VLAN traffic.

## IP configuration

Rackdog does not hand out IP addresses inside your VLAN. You pick the subnet and configure addresses on each server yourself.

### Example (Ubuntu / Netplan)

**Server 1:**

```
10.10.10.1/24
```

**Server 2:**

```
10.10.10.2/24
```

Apply the Netplan config on both servers and they'll be able to reach each other over the VLAN.

## Things to know

* VLANs operate at Layer 2 only. There's no routing by default.
* IP addressing, subnet design, and any routing between VLANs are your responsibility. If you need to connect multiple VLANs, use a dedicated server as the router.

## A typical workflow

1. Create a VLAN via the API.
2. Attach two or more servers.
3. Configure private IPs on each server.
4. Verify with a ping between them.

## Good habits

* Attach at least two servers so the VLAN actually activates.
* Use consistent subnetting across servers in the same VLAN.
* Keep private addressing organized, for example by environment or service.

## When to use VLANs

Reach for a VLAN when you want private traffic between servers, isolation from the public internet, or a custom topology across your fleet.