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Configure Legacy Inter-VLAN Routing on Cisco Router

In this guide, we’ll walk you through the steps to configure legacy inter-VLAN routing on a Cisco router. Inter-VLAN routing allows different VLANs to communicate with each other. This setup is crucial in network environments that need to segment traffic for security and management purposes while still enabling communication between VLANs.

Network Topology

The network topology consists of a router, a switch, and four PCs divided into two VLANs:

• VLAN 10 (IT) with IP range 192.168.10.0/24
• VLAN 20 (HR) with IP range 192.168.20.0/24

The router interfaces are configured as follows:

• Gig0/0/1: 192.168.10.1 assigned to VLAN 10
• Gig0/0/0: 192.168.20.1 assigned to 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

Step-by-Step Configuration

Router Configuration

1. Access the router and enter privileged EXEC mode:

   Router>enable

2. Enter global configuration mode:

   Router#configure terminal
   Router(config)#hostname R1

3. Configure the interfaces:
   • For VLAN 10:

     R1(config)#interface gigabitEthernet 0/0/1
     R1(config-if)#no shutdown
     R1(config-if)#ip address 192.168.10.1 255.255.255.0
     R1(config-if)#exit

   • For VLAN 20:

     R1(config)#interface gigabitEthernet 0/0/0
     R1(config-if)#no shutdown
     R1(config-if)#ip address 192.168.20.1 255.255.255.0
     R1(config-if)#exit

Switch Configuration

1. Access the switch and enter privileged EXEC mode:

   Switch>enable

2. Enter global configuration mode:

   Switch#configure terminal
   Switch(config)#hostname S1

3. Create VLANs and assign names:
   • VLAN 10:

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

   • VLAN 20:

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

4. Assign VLANs to the switch ports:
   • For VLAN 10:

     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

   • For VLAN 20:

     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

5. Assign VLANs to the router interfaces:
   • For VLAN 20:

     S1(config)#interface gigabitEthernet 0/1
     S1(config-if)#switchport mode access
     S1(config-if)#switchport access vlan 20
     S1(config-if)#exit

   • For VLAN 10:

     S1(config)#interface gigabitEthernet 0/2
     S1(config-if)#switchport mode access
     S1(config-if)#switchport access vlan 10
     S1(config-if)#exit

Conclusion

By following these steps, you can successfully configure legacy inter-VLAN routing on a Cisco router. This setup ensures that different VLANs can communicate with each other, enhancing network efficiency and management. Proper VLAN configuration and inter-VLAN routing are essential for maintaining a segmented yet interconnected network environment.

Feel free to leave any questions or comments below and happy networking!