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How do I create VLAN?

Published in VLAN Configuration 4 mins read

Creating a VLAN (Virtual Local Area Network) involves logically segmenting a physical network into multiple broadcast domains. Here's a breakdown of how to create a VLAN, incorporating information from the provided reference:

Steps to Create a VLAN

  1. Brainstorm VLAN Groupings: Determine how you want to segment your network. Common groupings include by department (e.g., Sales, Engineering), by device type (e.g., printers, servers), or by security level.
  2. Prepare Unique VLAN IDs: Assign a unique VLAN ID to each VLAN. VLAN IDs typically range from 1 to 4094. VLAN 1 is usually the default VLAN and is generally not recommended for user traffic.
  3. Create a Logical Network Diagram or Map: Document your VLAN plan. A network diagram helps visualize the VLAN layout, assigned ports, and device connectivity, making configuration and troubleshooting easier.
  4. Optional: Purchase Additional Equipment: In some cases, you might need additional switches or routers to support your VLAN configuration, especially in larger networks or if your existing equipment is not VLAN-capable.
  5. Connect Network Devices to Appropriate Switch Ports: Physically connect the network devices to the switch ports according to your VLAN plan.
  6. Configure Switch Ports: Access the switch's configuration interface (usually via a web browser, command-line interface (CLI), or dedicated management software). Configure each port to either access mode or trunk mode.
    • Access Mode: A port in access mode carries traffic for only one VLAN. This is typical for connecting end-user devices like computers and printers.
    • Trunk Mode: A port in trunk mode can carry traffic for multiple VLANs. Trunk ports are used to connect switches to each other or to a router that performs inter-VLAN routing.
  7. Set up VLAN Specifications via Network Switch Settings: Create the VLANs on the switch using their assigned VLAN IDs. This involves defining the VLAN in the switch's configuration.
  8. Assign Switch Ports to VLANs: Assign each switch port to the appropriate VLAN. For access ports, specify the VLAN ID for the port. For trunk ports, configure the allowed VLANs that can pass through the port.

Example Configuration (Illustrative)

Let's say you want to create two VLANs:

  • VLAN 10: For the Sales department.
  • VLAN 20: For the Engineering department.

Steps:

  1. VLAN IDs: You've chosen VLAN ID 10 for Sales and VLAN ID 20 for Engineering.

  2. Port Assignments:

    • Ports 1-10 are for Sales computers (connect these devices to these ports).
    • Ports 11-20 are for Engineering computers (connect these devices to these ports).
    • Port 24 connects to another switch.

  3. Switch Configuration (Conceptual):

    // Create VLANs
create vlan 10
create vlan 20

// Configure access ports for VLAN 10 (Sales)
configure port 1 vlan 10 access
configure port 2 vlan 10 access
...
configure port 10 vlan 10 access

// Configure access ports for VLAN 20 (Engineering)
configure port 11 vlan 20 access
configure port 12 vlan 20 access
...
configure port 20 vlan 20 access

// Configure trunk port (example assuming using 802.1q)
configure port 24 mode trunk encapsulation dot1q
configure port 24 trunk allowed vlan add 10,20

    Note: The exact commands vary depending on the switch vendor (Cisco, Juniper, HP, etc.). Consult your switch's documentation for the correct syntax.

Best Practices

  • Security: VLANs enhance security by isolating traffic.
  • Performance: VLANs can improve network performance by reducing broadcast traffic within each VLAN.
  • Management: VLANs simplify network management by grouping devices logically.
  • Documentation: Keep detailed records of your VLAN configuration.

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