VLAN Configuration Lab

Imagine you’ve just joined a mid-sized company as the new network administrator.
Your first task involves VLAN configuration to place the Sales and Tech teams into separate broadcast domains.

Figure 1 – Topology used to configure VLANs

Your goal in this lab is to fix that by creating:

• VLAN 10 for Sales

• VLAN 20 for Tech

Let’s get started!

In this first step, your goal is to create the two VLANs we will use throughout the lab:

• VLAN 10 for the Sales team

• VLAN 20 for the Tech team

Each VLAN will act as a separate broadcast domain.

Figure 2 – VLAN Topology

Before we start creating anything, let's look at SW1's current VLAN configuration

Check Existing VLANs

To see all VLANs configured on the switch, enter the following command:

SW1# show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, Fa0/2, Fa0/3, Fa0/4
                                                Fa0/5, Fa0/6, Fa0/7, Fa0/8
                                                Fa0/9, Fa0/10, Fa0/11, Fa0/12
                                                Fa0/13, Fa0/14, Fa0/15, Fa0/16
                                                Fa0/17, Fa0/18, Fa0/19, Fa0/20
                                                Fa0/21, Fa0/22, Fa0/23, Fa0/24
                                                Gig0/1, Gig0/2
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active 

As you can see, the switch currently has VLAN 1, which is the default VLAN, and all interfaces are assigned to it.

You can also see VLANs 1002 to 1005. These VLANs are created automatically on Cisco switches and correspond to very old technologies.
We don’t need them for this lab, so you can safely ignore them.

Right now, everything is in VLAN 1, meaning Sales and Tech traffic is mixed together.
Let’s change that by creating the two VLANs we need.

Entering Configuration Mode

To create the VLANs, we first need to enter global configuration mode.
This mode allows you to modify the switch’s behavior, including VLANs, interfaces, and many other features.

SW1# configure terminal

This command moves you out of user EXEC mode and into the configuration environment, where you can start applying changes to the switch.

Create VLAN 10 (Sales)

Let’s begin by creating the first VLAN for the Sales team.

SW1(config)# vlan 10
SW1(config-vlan)# name Sales
SW1(config-vlan)# exit

You’ve now added VLAN 10 to the switch’s VLAN database.
At this moment, it exists on the switch, but no interfaces are assigned to it yet, so it doesn’t impact traffic.

Create VLAN 20 (Tech)

Now repeat the same process for the Tech department:

SW1(config)# vlan 20
SW1(config-vlan)# name Tech
SW1(config-vlan)# exit

Just like VLAN 10, VLAN 20 is now created inside the switch’s VLAN database.
However, since no ports belong to it yet, nothing has changed on the network.

Verifying VLAN Creation

Before we continue, let’s make sure both VLANs were successfully created.
Use the command below to display all VLANs on the switch:

SW1# show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, Fa0/2, Fa0/3, Fa0/4
                                                Fa0/5, Fa0/6, Fa0/7, Fa0/8
                                                Fa0/9, Fa0/10, Fa0/11, Fa0/12
                                                Fa0/13, Fa0/14, Fa0/15, Fa0/16
                                                Fa0/17, Fa0/18, Fa0/19, Fa0/20
                                                Fa0/21, Fa0/22, Fa0/23, Fa0/24
                                                Gig0/1, Gig0/2
10   Sales                            active    
20   Tech                             active    
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active    

Understanding the Output

You can now see that VLAN 10 and VLAN 20 both exist on the switch.
However, all switchports are still assigned to VLAN 1, which is the default VLAN for every interface.

This means that, for the moment, traffic from Sales and Tech is still mixed together.
There is no separation between the two groups yet, and that’s expected, VLANs only become effective once you assign interfaces to them.

Quick Recap

So far, you’ve learned how to:

• Enter configuration mode on a Cisco switch

• Create VLANs and name them properly

• Verify their presence using show vlan brief

In the next section, we’ll assign specific switch ports to each VLAN so that the Sales and Tech devices become properly separated into their own broadcast domains.

Now that your VLANs exist in the switch’s VLAN database, it’s time to assign the correct interfaces to each VLAN.

This is the moment where the logical separation becomes real: by mapping physical ports to specific VLANs, you ensure that the Sales and Tech teams no longer share the same broadcast domain.

Figure 3 – Access Port Configuration per VLAN

To do this, you’ll use two key commands:

• switchport mode access

• switchport access vlan X

Let’s apply them step by step.

Assigning Sales Ports (VLAN 10)

The Sales team devices are connected to interfaces Fa0/1 and Fa0/2.
Let’s start with the first port:

SW1(config)# interface f0/1
SW1(config-if)# switchport mode access
SW1(config-if)# switchport access vlan ?
  <1-4094>  VLAN ID of the VLAN when this port is in access mode

SW1(config-if)# switchport access vlan 10
SW1(config-if)# exit

These commands do two things: