802.1Q Configuration Lab

In this lab, you will learn how to configure 802.1Q trunking between two switches so VLANs can extend across multiple devices.

This is the topology we will use to practice the concept of 802.1Q Trunking.

Figure 1 – 802.1Q Configuration Topology

This lab will guide you through the configuration, verification, and testing of 802.1Q trunks so you understand exactly how VLANs propagate between switches.

The switch connections are already in place, so you can focus entirely on the VLAN and trunk configuration.

Addressing used in this lab:
PC1 (VLAN 10) → 10.0.1.1 /24
PC3 (VLAN 10) → 10.0.1.3 /24
PC2 (VLAN 20) → 10.0.2.2 /24
PC4 (VLAN 20) → 10.0.2.4 /24

Notice that PC1 and PC3 share the same subnet, and PC2 and PC4 share another one. Each VLAN stays inside a single subnet, so no router is needed in this lab. The trunk alone is enough to carry VLAN 10 and VLAN 20 traffic between the two switches. If you rebuild this topology in Packet Tracer, use exactly these addresses and masks, otherwise your pings will time out.

Lab Overview

Here’s the structure we will follow throughout this lab:

Step 1 – Configure VLANs and Access Ports on SW1
Step 2 – Configure VLANs and Access Ports on SW2
Step 3 – Configure 802.1Q Trunking
Step 4 – Verify Trunk Behavior

Let’s get started!

To begin, we need to create the two VLANs used in this topology: VLAN 10 and VLAN 20.

Figure 2 – 802.1Q Topology Example

Create VLAN 10 and VLAN 20

The process of creating a VLAN is simple.
You only need to enter the VLAN number, and you can optionally assign a name to make the configuration easier to read.

SW1# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)# vlan 10
SW1(config-vlan)# name Sales
SW1(config-vlan)# exit

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

Then, after creating VLAN 10 and VLAN 20, we can verify that the VLANs are present.
On the switch, type the command show vlan brief

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    

Our two VLANs are now created, and we must assign them to the correct ports.

Assign Ports to the Correct VLANs

We assign VLAN 10 to the interface connected to PC1, and VLAN 20 to the interface connected to PC2.

Figure 3 – VLAN Access on SW1

Take a look at Figure 3 to see how the access VLAN configuration should look.

SW1# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)# int f0/1
SW1(config-if)# switchport mode access 
SW1(config-if)# switchport access vlan 10
SW1(config-if)# exit

SW1(config)# int f0/2
SW1(config-if)# switchport mode access
SW1(config-if)# switchport access vlan 20
SW1(config-if)# end

Verify the VLAN Assignment

We can verify this again using:

SW1# show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    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    Fa0/1
20   Tech                             active    Fa0/2
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active   

Perfect, the PCs are now assigned to the correct VLANs.
We need to do the same on SW2 before moving on to the 802.1Q configuration.

Now let’s do the exact same configuration on SW2.
Just like before, we need to create VLAN 10 and VLAN 20, then assign the correct interfaces to each VLAN.

Create VLAN 10 and VLAN 20

SW2# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW2(config)# vlan 10
SW2(config-vlan)# name Sales
SW2(config-vlan)# exit

SW2(config)# vlan 20
SW2(config-vlan)# name Tech
SW2(config-vlan)# exit

At this point, both VLANs exist on the switch but have no ports assigned to them yet.

Assign Ports to the Correct VLANs

According to Figure 4, we can see that PC3 is in VLAN 10, and PC4 is in VLAN 20. So we need to make sure we apply the VLAN to the correct interface.

The appropriate commands are shown below.

Figure 4 – VLAN Access on SW2

Let's do that on SW2.

SW2(config)# int f0/1
SW2(config-if)# switchport mode access 
SW2(config-if)# switchport access vlan 10
SW2(config-if)# exit

SW2(config)# int f0/2
SW2(config-if)# switchport mode access 
SW2(config-if)# switchport access vlan 20
SW2(config-if)# end

Verify the VLAN Assignment

We need to verify the VLAN association: