How to Configure OSPF Single Area

In this article, we will discuss how to configure OSPF single area.

For this configuration, I will use GNS3 and c3725-adventerprisek9-mz.124-15.T14 IOS router.

Steps for configuration.

• Setup topology on GNS3 and configure IP addresses showing in the diagram.
• Configure following loopbacks 0 on routers.
• R1 – 1.1.1.1/24
• R2 – 2.2.2.2/24
• R3 – 3.3.3.3/24
• Configure OSPF on all router with process-id 1 area 0.
• R1: Use area 0 and use 2 network statements to advertise all networks.
• R2: Use area 0 and use 1 network statement to advertise all networks.
• R3: use area 0 and use 3 network statements to advertise all networks.

Topology

Configurations of OSPF Single Area.

R1 configuration.

Configure interfaces, loopback and use 2 network statement.

R1(config)#router ospf 1
R1(config-router)#network 1.1.1.1 0.0.0.255 area 0
R1(config-router)#network 192.168.0.0 0.0.255.255 area 0

R2 configuration.

Configure interfaces, loopback and use 1 network statement.

R2(config)#router ospf 1
R2(config-router)#network 0.0.0.0 255.255.255.255 area 0

R3 configuration.

Configure interfaces, loopback and use 3 network statement.

R3(config)#router ospf 1
R3(config-router)#network 192.168.3.0 0.0.0.255 area 0
R3(config-router)#network 192.168.3.0 0.0.0.255 area 0
R3(config-router)#network 3.3.3.3 0.0.0.255 area 0

After the OSPF configuration verify all neighbors and routes on all routers.

Use show ip ospf neighbor for check neighbors.

Use show ip route for check all routes.

R1 neighbors and routes verifications

R2 neighbors and routes verifications

R3 neighbors and routes verifications