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

How to use GNS3

GNS3 (Graphical Network Simulator) is a great free ware to practice especially CCNA, CCNP or CCIE labs, without purchasing expensive hardware. All you need a PC with OS e.g., windows first go to http://www.gns3.net/download and download the software that is GNS3 v0.6.1 all-in-one for windows users and its tutorial from this url http://www2.gns3.net/trac/chrome/site/tutorial_gns3_draft_060407.pdf


1- Install gns3
2- Go to Edit > Preference > Click the TEST button and answer should be (Dynamips successfully started)
3- Go to Edit > IOS images and hypervisors and in front of IOS images browse and select the ios image of router which you want to use in lab, IOS images of routers are not provided by dynamips due to legal issues, you have to purchase or find it on web like torrents.
4- After that drag your router on topology window and right click on that router and START it
5- After starting again right click on router and select CONSOLE
6- When the IOS is uncompressed and you are in user privilege mode
7- You will observe System utilization will reach upto 100%
8- So come back to topology window where you added router and right click on it and select IDLE PC.
9- It will take some time to calculate the idle pc value and after that a window appear click its drop down and select the value which has astrick(*) in the start.
10- As soon as you apply this the processor utilization will come back to normal.
now practice and read the tutorial for illustrated help.

Author
Waqas Rafi