VLAN Configuration & Trunk Setup Lab

Hi there!
In this lab, I used Cisco Packet Tracer to configure VLANs and trunk ports.
Here’s the network setup and a step-by-step guide.

1, Network Topology

VLAN Topology Diagram
  1. Configure the switch interfaces connected to PCs as access ports assigned to the correct VLANs.
  2. Configure the trunk link between SW1 and SW2, allowing only necessary VLANs.
    Use an unused VLAN as the native VLAN.
    Ensure all required VLANs exist on both switches.
  3. Set up the connection between SW2 and R1 using "Router on a Stick".
    Assign the last usable IP address in each subnet to the router's subinterface.


2, How to Configure the Switches

  1. Create VLANs on each switch using vlan [ID] in global config mode.
  2. Assign access ports to VLANs:
    switchport mode access
    switchport access vlan [ID]
  3. Configure trunk ports:
    switchport mode trunk
    switchport trunk allowed vlan [ID,ID,...]
  4. Set a native VLAN (must be unused):
    switchport trunk native vlan [ID]
  5. Configure subinterfaces on the router:
    interface GigabitEthernet0/0.10
 encapsulation dot1Q 10
 ip address 192.168.10.254 255.255.255.0



3, Ping Test

Let’s try pinging each PC to verify communication.

Ping Failure Screenshot
Ping to 10.0.0.65 (PC5) was successful, but 10.0.0.2 (PC2) failed. This suggests a problem in the trunk link. Let’s inspect the switch config.
SW2 Config Error
Oops! A syntax mistake: I used a period (`.`) instead of a comma (`,`) when listing allowed VLANs. That caused the trunk to block necessary VLANs. Always double-check your syntax!
Revised Config
I fixed the trunk config. Time to test again!
Successful Ping
Success! I received replies from PC2 and PC3. Inter-VLAN routing is now working properly!
Simulation Mode Screenshot
Finally, I used simulation mode to trace the packets visually. 🎉
That’s all for this VLAN & trunking lab!