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Configure Inter-VLAN Routing as Router-on-a-Stick on Cisco Router

Inter-VLAN routing is crucial for allowing communication between different VLANs within a network. In this tutorial, we’ll configure inter-VLAN routing using the Router-on-a-Stick method on a Cisco router. Follow the steps below to set up the topology shown in the image.

Topology Overview

Type of Inter-VLAN Routing

1. Legacy Inter-VLAN Routing
2. Inter-VLAN Routing as Router-on-a-Stick
3. Inter-VLAN Routing as SVI

In this topology, we have:

• A Cisco Router (R1) connected to a Cisco Switch (S1) via a trunk link.
• Two VLANs:
  • VLAN 10 (IT) with subnet 192.168.10.0/24
  • VLAN 20 (HR) with subnet 192.168.20.0/24
• PCs in each VLAN:
  • PC10 and PC11 in VLAN 10
  • PC20 and PC21 in VLAN 20

Type of Inter-VLAN Routing

1. Legacy Inter-VLAN Routing
2. Inter-VLAN Routing as Router-on-a-Stick
3. Inter-VLAN Routing as SVI

Router Configuration

1. Enable the Router and Enter Global Configuration Mode

   Router>enable
   Router#configure terminal
   Router(config)#hostname R1
   

2. Configure the Physical Interface (GigabitEthernet 0/0/0)

   R1(config)#interface gigabitEthernet 0/0/0
   R1(config-if)#no shutdown
   R1(config-if)#exit
   

3. Create Sub-Interface for VLAN 10

   R1(config)#interface gigabitEthernet 0/0/0.10
   R1(config-subif)#encapsulation dot1Q 10
   R1(config-subif)#ip address 192.168.10.1 255.255.255.0
   R1(config-subif)#exit
   

4. Create Sub-Interface for VLAN 20

   R1(config)#interface gigabitEthernet 0/0/0.20
   R1(config-subif)#encapsulation dot1Q 20
   R1(config-subif)#ip address 192.168.20.1 255.255.255.0
   R1(config-subif)#exit
   

Switch Configuration

1. Enable the Switch and Enter Global Configuration Mode

   Switch>enable
   Switch#configure terminal
   Switch(config)#hostname S1
   

2. Create VLANs and Assign Names

   S1(config)#vlan 10
   S1(config-vlan)#name IT
   S1(config-vlan)#exit
   
   S1(config)#vlan 20
   S1(config-vlan)#name HR
   S1(config-vlan)#exit
   

3. Assign VLANs to Ports

   S1(config)#interface range fastEthernet 0/10-11
   S1(config-if-range)#switchport mode access
   S1(config-if-range)#switchport access vlan 10
   S1(config-if-range)#exit
   
   S1(config)#interface range fastEthernet 0/20-21
   S1(config-if-range)#switchport mode access
   S1(config-if-range)#switchport access vlan 20
   S1(config-if-range)#exit
   

4. Configure Trunk Port

   S1(config)#interface gigabitEthernet 0/1
   S1(config-if)#switchport mode trunk
   S1(config-if)#exit
   

Conclusion

By following these steps, you have successfully configured inter-VLAN routing using the Router-on-a-Stick method on a Cisco router. This setup enables communication between devices in different VLANs while maintaining VLAN segmentation.

Feel free to leave a comment if you have any questions or run into any issues!