Multiple Area OSPF and Virtual Link

This lab is about multiple area ospf and creating a virtual link to start communication between area 0 and area 2. Here we have three routers A,B and C connected via serial port and each router connecting their segments. Each router has it own loop back interface, now we will start our configurations. Make sure to configure loop back first than configure OSPF, with this OSPF will become router id.

OSPF Configurations
===================
(A Configurations)
A(config)#int loopback 0
A(config-if)#ip add 11.1.1.1 255.255.255.255
!
A(config)#int s1/0
A(config-if)#ip add 1.1.1.1 255.0.0.0
A(config)#no shut
!
A(config)#int fa0/0
A(config-if)#ip add 200.100.50.50 255.255.255.0
A(config-if)#no shut
!
A(config)#Router ospf 1
A(config-router)#network 11.1.1.1 0.0.0.0 area 2
A(config-router)#network 1.0.0.0 0.255.255.255 area 2
A(config-router)#network 200.100.50.0 0.0.0.255 area 2
!
A#sh ip route
A#sh ip ospf
A#sh ip protocols

(B configurations)
Configure interfaces and now comes OSPF part as below
!
B(config)#Router ospf 1
B(config-router)#network 11.1.1.1 0.0.0.0 area 1
B(config-router)#network 1.0.0.0 0.255.255.255 area 2
B(config-router)#network 2.0.0.0 0.255.255.255 area 1
B(config-router)#network 200.100.100.0 0.0.0.255 area 1

B#sh ip route
B#sh ip ospf
B#sh ip protocols

(C configurations)
Configure interfaces and now comes OSPF part as below
!
C(config)#Router ospf 1
C(config-router)#network 33.3.3.3 0.0.0.0 area 0
C(config-router)#network 2.0.0.0 0.255.255.255 area 1
C(config-router)#network 200.100.150.0 0.0.0.255 area 0

C#sh ip route
C#sh ip ospf
C#sh ip protocols
!
Now CREATING A VIRTUAL LINK TO EXTEND THE BACKBONE AREA 0 TO COMMUNICATE WITH AREA 2. Areas touching routers are,,
A { A2 }
B { A2, A1 }
C { A1, A0 }
Virtual Link will create between B and C because both routers have same area (A1) and a backbone area (A0) also.

GO TO "B"
B(config)#router ospf 1
B(config-router)#area 1 virtual-link 33.3.3.3
!
GO TO "C"
C(config)#router ospf 1
c(config-router)#area 1 virtual-link 22.2.2.2

Now see convergence is complete, and u can ping any network in this topology.

Author
WAQAS RAFI