To access multiple VLANs from a single location, you do not need to be physically “inside” each VLAN.

Instead, you can configure your network to allow communication between VLANs, a process known as “Inter-VLAN routing.” This process is usually performed on a router or a multilayer switch that can perform routing functions.

We explain how to do it:

Inter-VLAN Routing Configuration

1. Router with Multiple Interfaces: A traditional way to configure Inter-VLAN routing is to use a router with multiple physical interfaces, where each interface connects to a switch configured for a specific VLAN. However, this method is neither scalable nor efficient in terms of costs and available ports.
2. Router-on-a-Stick: This method uses a single physical interface on a router to handle multiple VLANs through subinterfaces. Each subinterface is configured for a specific VLAN using 802.1Q tagging. The switch to which the router is connected must have the corresponding ports configured as trunk to allow traffic from all VLANs through that single physical connection.
3. Layer 3 Switches (Multilayer): Layer 3 switches can perform routing between VLANs internally without the need for an external router. You can configure Switched Virtual Interfaces (SVI) for each VLAN on the Layer 3 switch, allowing the switch to route traffic between VLANs as needed.

Security Considerations

• Access Control Lists (ACLs): Regardless of which method you use, it is important to implement ACLs to control what traffic can pass between VLANs. This allows you to restrict access to sensitive resources and ensure that only authorized users can communicate between specific VLANs.
• Security politics: Ensure your security policies are updated to reflect the ability to communicate between VLANs, including protection against insider threats and compliance with data isolation policies.

Configuration

• Routing Device Configuration: Depending on the device you are using (Cisco router, MikroTik Layer 3 switch, etc.), the specific process for configuring Inter-VLAN routing will vary. Consult your device's documentation for detailed instructions on how to configure inter-VLAN routing and ACLs.

In short, you don't need to be inside each VLAN individually to access all the others; By properly configuring your network infrastructure and routing devices, you can facilitate communication between different VLANs securely and efficiently.