OSPF Backbone Area, Standard Area and Vitual-Links

In this article series we will concentrate on OSPF Area Types and their configuration examples on Packet Tracer.

You can DOWNLOAD the Packet Tracer example with .pkt format HERE.

As you know from the previous posts, OSPF has 6 different areas. These areas are:

– Backbone Area

– Standard (Normal) Area

– Stub Area

– Totally-Stub Area

– Not-So-Stubby Area (NSSA)

– Totally Not-So-Stubby Area

In this first post, we will focus on Backbone Area and Standard (Normal) Area. Beside this, we will see the configuration of virtual-link on OSPF. What was the virtual-link? It was the link that used to connect the normal areas to the backbone area, if they are not connected directly to the backbone area. Remember, in OSPF, there was a rule. All areas must be connected to the backbone area, Area 0. If they are not, they can temporarily connect to the backbone via virtual-links.



OSPF Backbone Area and Standard Area with Accepted LSAs

Backbone Area is also a Normal Area but it is Area 0.

Normal Areas accept the Summary LSAs from other Areas (Type 3 and Type 4 LSAs). They accept also the External LSAs (Type 5 LSAs). Type 1 and Type 2 LSA are already accepted inside area.

We talked about theorical too much. This post aims to show you the configuration of this areas and as you know, doing the configuration is the most effective way of learning network protocols.

Our topology will be like below fort he first example.



OSPF Backbone Area, Standard Area and

Virtual-Link Example Topology

As you can see, in this topology, there areand

Firstly let’s configure the IP Addresses on all routers:

Router1

Router1>enable Router1# configure terminal Router1(config)# interface GigabitEthernet0/0 Router1(config-if)# ip address 10.1.0.1 255.255.255.0 Router1(config-if)# no shutdown Router1(config-if)# exit Router1(config)# interface GigabitEthernet0/1 Router1(config-if)# ip address 10.2.0.1 255.255.255.0 Router1(config-if)# no shutdown Router1(config-if)# end Router1# copy running-config startup-config

Router2

Router2>enable Router2# configure terminal Router2(config)# interface GigabitEthernet0/0 Router2(config-if)# ip address 10.1.0.2 255.255.255.0 Router2(config-if)# no shutdown Router2(config-if)# exit Router2(config)# interface GigabitEthernet0/1 Router2(config-if)# ip address 10.3.0.1 255.255.255.0 Router2(config-if)# no shutdown Router2(config-if)# end Router2# copy running-config startup-config

Router3

Router3>enable Router3# configure terminal Router3(config)# interface GigabitEthernet0/0 Router3(config-if)# ip address 10.2.0.2 255.255.255.0 Router3(config-if)# no shutdown Router3(config-if)# exit Router3# copy running-config startup-config

Router4

Router4>enable Router4# configure terminal Router4(config)# interface GigabitEthernet0/0 Router4(config-if)# ip address 10.4.0.1 255.255.255.0 Router4(config-if)# no shutdown Router4(config-if)# exit Router4(config)# interface GigabitEthernet0/1 Router4(config-if)# ip address 10.3.0.2 255.255.255.0 Router4(config-if)# no shutdown Router4(config-if)# end Router4# copy running-config startup-config

Router5

Router5>enable Router5# configure terminal Router5(config)# interface GigabitEthernet0/0 Router5(config-if)# ip address 10.4.0.2 255.255.255.0 Router5(config-if)# no shutdown Router5(config-if)# exit Router5(config)# interface GigabitEthernet0/1 Router5(config-if)# ip address 10.5.0.1 255.255.255.0 Router5(config-if)# no shutdown Router5(config-if)# end Router5# copy running-config startup-config

Router6

Router6>enable Router6# configure terminal Router6(config)# interface GigabitEthernet0/1 Router6(config-if)# ip address 10.5.0.2 255.255.255.0 Router6(config-if)# no shutdown Router6(config-if)# end Router6# copy running-config startup-config

After this basic interface configurations, let’s configure the OSPF on all routers. Here, OSPF process number will be 1 and the Routerx’s router ID will be x.x.x.x. Beside this, all the connected areas will be configured.

Router1

Router1>enable Router1# configure terminal Router1(config)# router ospf 1 Router1(config-router)# router-id 1.1.1.1 Router1(config-router)# network 10.1.0.0 0.0.0.255 area 0 Router1(config-router)# network 10.2.0.0 0.0.0.255 area 1 Router1(config-router)# end Router1# copy running-config startup-config

Router2

Router2>enable Router2# configure terminal Router2(config)# router ospf 1 Router2(config-router)# router-id 2.2.2.2 Router2(config-router)# network 10.1.0.0 0.0.0.255 area 0 Router2(config-router)# network 10.3.0.0 0.0.0.255 area 2 Router2(config-router)# end Router2# copy running-config startup-config

Router3

Router3>enable Router3# configure terminal Router3(config)# router ospf 1 Router3(config-router)# router-id 3.3.3.3 Router3(config-router)# network 10.2.0.0 0.0.0.255 area 1 Router3(config-router)# end Router3# copy running-config startup-config

Router4

Router4>enable Router4# configure terminal Router4(config)# router ospf 1 Router4(config-router)# router-id 4.4.4.4 Router4(config-router)# network 10.3.0.0 0.0.0.255 area 2 Router4(config-router)# network 10.4.0.0 0.0.0.255 area 2 Router4(config-router)# end Router4# copy running-config startup-config

Router5

Router5>enable Router5# configure terminal Router5(config)# router ospf 1 Router5(config-router)# router-id 5.5.5.5 Router5(config-router)# network 10.4.0.0 0.0.0.255 area 2 Router5(config-router)# network 10.5.0.0 0.0.0.255 area 3 Router5(config-router)# end Router5# copy running-config startup-config

Router6

Router6>enable Router6# configure terminal Router6(config)# router ospf 1 Router6(config-router)# router-id 6.6.6.6 Router6(config-router)# network 10.5.0.0 0.0.0.255 area 3 Router6(config-router)# end Router6# copy running-config startup-config

After doing this configuration we will see all the network on Topology Table except Area 3. Area 3 is not directly connected to the Backbone Area,Area 0. So in the routing table of the routers there will be no route to this Area 3.

Other OSPF Area Types on Packet Tracer Lessons

OSPF Area Types on Packet Tracer – Part 1 (Standard Area, Backbone Area, Virtual-Link)

OSPF Area Types on Packet Tracer – Part 2 (OSPF External Routes)

OSPF Area Types on Packet Tracer – Part 3 (Stub Area, Totally-Stub Area, NSSA, Totally NSSA)

You can check the other Packet Tracer Examples below:

Common Cisco Router Configuration Example on Packet Tracer

Router DHCP Configuration Example on Packet Tracer

VTP Configuration Example on Packet Tracer

VLAN Configuration Example on Packet Tracer

STP Configuration Example on Packet Tracer

BGP Configuration Example on Packet Tracer

Port Security Configuration Example on Packet Tracer

RIP Configuration Example on Packet Tracer

CDP Configuration Example on Packet Tracer

OSPF Area Types Example on Packet Tracer (Standard and Backbone Areas)

OSPF External Routes Example on Packet Tracer

OSPF Area Types Example on Packet Tracer (Stub, NSSA, Totally Stubby, Totally NSSA Areas)