How to configure VLANs on an access switch

To configure VLANs on an access switch, create the VLANs, assign ports to them, configure trunk links if needed, and verify connectivity.

Step 1: Plan VLANs

Before configuring, determine the VLAN IDs and names, which ports will be access ports, and which ports will be trunk links. Decide if the switch will only perform Layer 2 switching or also provide Layer 3 gateway functions through SVIs. Ensure you know whether a management VLAN is required for remote access via SSH or Telnet .

Step 2: Create VLANs

Enter global configuration mode on the switch and create VLANs using the vlan command. Assign a meaningful name to each VLAN for easier management. For example, to create VLAN 10 and VLAN 20:

Switch> enableSwitch# configure terminalSwitch(config)# vlan 10Switch(config-vlan)# name SalesSwitch(config-vlan)# exitSwitch(config)# vlan 20Switch(config-vlan)# name MarketingSwitch(config-vlan)# exit

This creates the VLANs and allows you to configure additional options if needed .

Step 3: Assign Access Ports to VLANs

Access ports connect end devices like PCs or printers and belong to a single VLAN. Enter interface configuration mode and assign the VLAN using the switchport mode access and switchport access vlan commands:

Switch(config)# interface GigabitEthernet0/1Switch(config-if)# switchport mode accessSwitch(config-if)# switchport access vlan 10Switch(config-if)# exitSwitch(config)# interface GigabitEthernet0/2Switch(config-if)# switchport mode accessSwitch(config-if)# switchport access vlan 20Switch(config-if)# exit

Repeat this for all access ports that need to be assigned to VLANs .

Step 4: Configure Trunk Ports (if connecting switches)

If the switch connects to another switch, configure the uplink ports as trunks to carry multiple VLANs:

Switch(config)# interface GigabitEthernet0/24Switch(config-if)# switchport mode trunkSwitch(config-if)# exit

Trunk ports use 802.1Q tagging to carry traffic for multiple VLANs .

Step 5: Verify VLAN Configuration

Use the following commands to verify VLANs and port assignments:

• show vlan brief – displays VLANs and their assigned ports.
• show interfaces trunk – shows trunk ports and allowed VLANs.
• ping or test connectivity – verify devices in the same VLAN can communicate, and inter-VLAN routing works if configured .

Step 6: Optional Configurations

• Voice VLAN: Assign a separate VLAN for IP phones using switchport voice vlan <VLAN_ID>.
• Management VLAN: Configure an SVI for remote management if needed.
• SVI for Layer 3: If inter-VLAN routing is required, configure an SVI on a Layer 3 switch with an IP address for each VLAN . By following these steps, you can segment your network into logical VLANs, isolate broadcast domains, and improve network security and performance.