Configure OSPFv2 Single Area on Cisco Router (Multiaccess – Ethernet Interface)

In this tutorial, we will explore how to configure OSPFv2 Single Area on a Cisco router with a multiaccess Ethernet interface. The process involves configuring interfaces and enabling OSPF on routers based on a provided topology. The setup uses two routers (R1 and R2) and multiple PCs connected in different subnets.

Dynamic Routing – OSPFv2 (IPv4)

1. Configure OSPFv2 Single Area on Cisco Router (Multiaccess – Ethernet Interface)
2. Configure OSPFv2 Single Area on Cisco Router (Point to Point – Serial Interface)

Topology Overview

The topology consists of the following components:

• R1 connected to:
  • Subnet: 192.168.10.0/24 (PC10)
  • Subnet: 192.168.20.0/24 (PC20)
  • Subnet: 192.168.30.0/24 (shared link to R2)
• R2 connected to:
  • Subnet: 192.168.40.0/24 (PC40)
  • Subnet: 192.168.50.0/24 (PC50)
  • Subnet: 192.168.30.0/24 (shared link to R1)

Each subnet is configured on GigabitEthernet or FastEthernet interfaces.

Router Configuration

Below are the step-by-step configurations for both routers:

Router R1 Configuration

1. Set the hostname:

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

2. Configure Interfaces:
   • GigabitEthernet 0/0/1 (Connected to PC10):

     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
     

   • GigabitEthernet 0/0/2 (Connected to PC20):

     R1(config)# interface gigabitEthernet 0/0/2
     R1(config-if)# no shutdown
     R1(config-if)# ip address 192.168.20.1 255.255.255.0
     R1(config-if)# exit
     

   • GigabitEthernet 0/0/0 (Connected to R2):

     R1(config)# interface gigabitEthernet 0/0/0
     R1(config-if)# no shutdown
     R1(config-if)# ip address 192.168.30.1 255.255.255.0
     R1(config-if)# exit
     

3. Enable OSPFv2:

   R1(config)# router ospf 1
   R1(config-router)# network 192.168.10.0 0.0.0.255 area 0
   R1(config-router)# network 192.168.20.0 0.0.0.255 area 0
   R1(config-router)# network 192.168.30.0 0.0.0.255 area 0
   R1(config-router)# exit
   

Router R2 Configuration

1. Set the hostname:

   Router> enable
   Router# configure terminal
   Router(config)# hostname R2
   

2. Configure Interfaces:
   • GigabitEthernet 0/0/1 (Connected to PC40):

     R2(config)# interface gigabitEthernet 0/0/1
     R2(config-if)# no shutdown
     R2(config-if)# ip address 192.168.40.1 255.255.255.0
     R2(config-if)# exit
     

   • GigabitEthernet 0/0/2 (Connected to PC50):

     R2(config)# interface gigabitEthernet 0/0/2
     R2(config-if)# no shutdown
     R2(config-if)# ip address 192.168.50.1 255.255.255.0
     R2(config-if)# exit
     

   • GigabitEthernet 0/0/0 (Connected to R1):

     R2(config)# interface gigabitEthernet 0/0/0
     R2(config-if)# no shutdown
     R2(config-if)# ip address 192.168.30.2 255.255.255.0
     R2(config-if)# exit
     

3. Enable OSPFv2:

   R2(config)# router ospf 1
   R2(config-router)# network 192.168.30.0 0.0.0.255 area 0
   R2(config-router)# network 192.168.40.0 0.0.0.255 area 0
   R2(config-router)# network 192.168.50.0 0.0.0.255 area 0
   R2(config-router)# exit
   

Verification

After completing the configurations, you can verify the OSPF settings and connectivity:

1. Check OSPF neighbors:

   R1# show ip ospf neighbor
   R2# show ip ospf neighbor
   

2. Check OSPF routing table:

   R1# show ip route
   R2# show ip route
   

3. Ping between PCs across routers:
   • From PC10 (192.168.10.10), ping PC50 (192.168.50.10):

     > ping 192.168.50.10
     

   • From PC20 (192.168.20.10), ping PC40 (192.168.40.10):

     > ping 192.168.40.10
     

Conclusion

This configuration ensures that OSPFv2 is operational in a single area across multiaccess Ethernet interfaces. This setup allows for dynamic routing and efficient network communication between subnets.