How to Configure OSPF Multi Area

In this section, we will discuss how to configure OSPF Multi-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 OSPF on all router with process-id 1.
Configure OSPF router id manually on all router on R1-1.1.1.1, R2-2.2.2.2, R3-3.3.3.3, R4-4.4.4.4, and R5-5.5.5.5.
R1 fa0/0 and fa0/1 interface should be in area 0.
R2 fa0/0 should be in area 0 and fa0/1 in area 10.
R3 fa0/1 should be in area 0 and fa0/0 in area 20.
R4 fa0/1 should be in area 10.
R5 fa0/0 should be in area 20.
Create loopback interfaces. R1 loopback 0 – 11.11.11.11/24 on area 0, R2 loopback 0 – 22.22.22.22/24 area 0, R3 loopback 0 33.33.33.33/24 area 0, R4 loopback 0 – 44.44.44.44.44/24 area 10, and R5 loopback 0 – 55.55.55.55/24 on area 20
Verify routes and neighbors.

Topology

Configuration of OSPF Multi-Area.

R1 Configuration

R1(config)#router ospf 1
R1(config-router)#router-id 1.1.1.1
R1(config-router)#network 0.0.0.0 255.255.255.255 area 0

R2 Configuration

R2(config)#router ospf 1
R2(config-router)#router-id 2.2.2.2
R2(config-router)#network 192.168.1.0 0.0.0.255 area 0
R2(config-router)#network 192.168.10.0 0.0.0.255 area 10
R2(config-router)#network 22.22.22.22 0.0.0.0 area 0

R3 Configuration

R3(config)#router ospf 1
R3(config-router)#router-id 3.3.3.3
R3(config-router)#network 192.168.2.0 0.0.0.255 area 0
R3(config-router)#network 192.168.20.0 0.0.0.255 area 20
R3(config-router)#network 33.33.33.33 0.0.0.0 area 0

R4 Configuration

R4(config)#router ospf 1
R4(config-router)#router-id 4.4.4.4
R4(config-router)#network 192.168.10.0 0.0.0.255 area 10
R4(config-router)#network 44.44.44.44 0.0.0.0 area 10

R5 Configuration

R5(config)#router ospf 1
R5(config-router)#router-id 5.5.5.5
R5(config-router)#network 192.168.20.0 0.0.0.255 area 20
R4(config-router)#network 55.55.55.55.55 0.0.0.0 area 20