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In this lesson we will concentrate on OSPF Standard Area and OSPF Backbone Area. We will do a Multi Area OSPF Configuration With Backbone Area and OSPF Standard Areas. In other lesson, we will also give example for the other OSPF Area Types and their configuration examples on Packet Tracer.
You can DOWNLOAD the Cisco Packet Tracer example with .pkt format at the end of this lesson.
As you know from the previous lessons, OSPF has 6 different areas. These areas are:
You can check the below lessons for the configuration of different OSPF Area Types:
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
You can also check Basic OSPF Confiuration
What is Packet Tracer? | Download Packet Tracer
Packet Tracer Labs Coure | Download Packet Tracer Labs
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.
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.
To overcome this issue, on Router 2 and Router 5, we will configure the virtual-link. After this configuration, we will see all the routes in all the routers’ Topology Tables.
Router2
Router2>enable
Router2# configure terminal
Router2(config)# router ospf 1
Router2(config-router)# area 2 virtual-link 5.5.5.5
Router2(config-router)# end
Router2# copy running-config startup-config
Router5
Router5>enable
Router5# configure terminal
Router5(config)# router ospf 1
Router5(config-router)# area 2 virtual-link 2.2.2.2
Router5(config-router)# end
Router5# copy running-config startup-config
Let’s verify the Routing Tables, Topology Databases (OSPF Databases) and OSPF Neighbourhip on all routers:
Router1
Router1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
2.2.2.2 1 FULL/DR 00:00:38 10.1.0.2 GigabitEthernet0/0
3.3.3.3 1 FULL/DR 00:00:37 10.2.0.2 GigabitEthernet0/1
Router1#show ip ospf database
OSPF Router with ID (1.1.1.1) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 223 0x8000000b 0x0079af 1
5.5.5.5 5.5.5.5 802 0x80000005 0x009874 1
2.2.2.2 2.2.2.2 228 0x8000000b 0x00e604 2
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.1.0.2 2.2.2.2 228 0x80000005 0x001b1b
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.2.0.0 1.1.1.1 1009 0x80000006 0x00d078
10.3.0.0 2.2.2.2 909 0x8000000a 0x009ea1
10.4.0.0 2.2.2.2 884 0x8000000b 0x009aa2
10.4.0.0 5.5.5.5 812 0x8000000e 0x0030fe
10.3.0.0 5.5.5.5 802 0x8000000f 0x0044e9
10.5.0.0 5.5.5.5 482 0x80000010 0x00200c
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 224 0x8000000a 0x008f98 1
3.3.3.3 3.3.3.3 229 0x80000009 0x000415 1
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.2.0.2 3.3.3.3 229 0x80000005 0x00f67e
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.1.0.0 1.1.1.1 1008 0x80000013 0x00c27a
10.3.0.0 1.1.1.1 902 0x80000014 0x00b286
10.4.0.0 1.1.1.1 879 0x80000015 0x00ae87
10.5.0.0 1.1.1.1 477 0x80000016 0x00aa88
Router1#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks
C 10.1.0.0/24 is directly connected, GigabitEthernet0/0
L 10.1.0.1/32 is directly connected, GigabitEthernet0/0
C 10.2.0.0/24 is directly connected, GigabitEthernet0/1
L 10.2.0.1/32 is directly connected, GigabitEthernet0/1
O IA 10.3.0.0/24 [110/2] via 10.1.0.2, 02:04:54, GigabitEthernet0/0
O IA 10.4.0.0/24 [110/3] via 10.1.0.2, 02:04:54, GigabitEthernet0/0
O IA 10.5.0.0/24 [110/4] via 10.1.0.2, 02:04:54, GigabitEthernet0/0
Router2
Router2#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/BDR 00:00:39 10.1.0.1 GigabitEthernet0/0
5.5.5.5 0 FULL/ - 00:00:39 10.4.0.2 OSPF_VL0
3.3.3.3 1 FULL/DR 00:00:39 10.3.0.2 GigabitEthernet0/1
Router2#show ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 349 0x8000000b 0x00e604 2
5.5.5.5 5.5.5.5 922 0x80000005 0x009874 1
1.1.1.1 1.1.1.1 344 0x8000000b 0x0079af 1
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.1.0.2 2.2.2.2 349 0x80000005 0x001b1b
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.3.0.0 2.2.2.2 1030 0x8000000a 0x009ea1
10.4.0.0 2.2.2.2 1005 0x8000000b 0x009aa2
10.2.0.0 1.1.1.1 1131 0x80000006 0x00d078
10.4.0.0 5.5.5.5 933 0x8000000e 0x0030fe
10.3.0.0 5.5.5.5 922 0x8000000f 0x0044e9
10.5.0.0 5.5.5.5 603 0x80000010 0x00200c
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 344 0x8000000a 0x0057c6 1
3.3.3.3 3.3.3.3 349 0x8000000d 0x001fc4 2
5.5.5.5 5.5.5.5 349 0x8000000a 0x00946e 1
Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.4.0.2 5.5.5.5 941 0x80000005 0x001739
10.3.0.2 3.3.3.3 349 0x80000006 0x003b8b
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.1.0.0 2.2.2.2 1039 0x8000000b 0x00b48c
10.2.0.0 2.2.2.2 1039 0x8000000c 0x00b08d
10.5.0.0 5.5.5.5 603 0x80000013 0x001a0f
10.1.0.0 5.5.5.5 335 0x80000014 0x005ccd
Router2#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks
C 10.1.0.0/24 is directly connected, GigabitEthernet0/0
L 10.1.0.2/32 is directly connected, GigabitEthernet0/0
O IA 10.2.0.0/24 [110/2] via 10.1.0.1, 02:06:09, GigabitEthernet0/0
C 10.3.0.0/24 is directly connected, GigabitEthernet0/1
L 10.3.0.1/32 is directly connected, GigabitEthernet0/1
O 10.4.0.0/24 [110/2] via 10.3.0.2, 02:15:59, GigabitEthernet0/1
O IA 10.5.0.0/24 [110/3] via 10.3.0.2, 02:10:17, GigabitEthernet0/1
Router3
Router3#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/BDR 00:00:34 10.2.0.1 GigabitEthernet0/1
Router3#show ip ospf database
OSPF Router with ID (3.3.3.3) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
3.3.3.3 3.3.3.3 394 0x80000009 0x000415 1
1.1.1.1 1.1.1.1 389 0x8000000a 0x008f98 1
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.2.0.2 3.3.3.3 394 0x80000005 0x00f67e
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.1.0.0 1.1.1.1 1174 0x80000013 0x00c27a
10.3.0.0 1.1.1.1 1067 0x80000014 0x00b286
10.4.0.0 1.1.1.1 1045 0x80000015 0x00ae87
10.5.0.0 1.1.1.1 642 0x80000016 0x00aa88
Router3#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks
O IA 10.1.0.0/24 [110/2] via 10.2.0.1, 02:47:08, GigabitEthernet0/1
C 10.2.0.0/24 is directly connected, GigabitEthernet0/1
L 10.2.0.2/32 is directly connected, GigabitEthernet0/1
O IA 10.3.0.0/24 [110/3] via 10.2.0.1, 02:47:08, GigabitEthernet0/1
O IA 10.4.0.0/24 [110/4] via 10.2.0.1, 02:17:52, GigabitEthernet0/1
O IA 10.5.0.0/24 [110/5] via 10.2.0.1, 02:11:08, GigabitEthernet0/1
Router4
Router4#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
5.5.5.5 1 FULL/DR 00:00:36 10.4.0.2 GigabitEthernet0/0
2.2.2.2 1 FULL/BDR 00:00:38 10.3.0.1 GigabitEthernet0/1
Router4#show ip ospf database
OSPF Router with ID (3.3.3.3) (Process ID 1)
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link count
3.3.3.3 3.3.3.3 429 0x8000000d 0x001fc4 2
5.5.5.5 5.5.5.5 429 0x8000000a 0x00946e 1
2.2.2.2 2.2.2.2 425 0x8000000a 0x0057c6 1
Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.3.0.2 3.3.3.3 429 0x80000006 0x003b8b
10.4.0.2 5.5.5.5 1021 0x80000005 0x001739
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.1.0.0 2.2.2.2 1119 0x8000000b 0x00b48c
10.2.0.0 2.2.2.2 1119 0x8000000c 0x00b08d
10.5.0.0 5.5.5.5 684 0x80000013 0x001a0f
10.1.0.0 5.5.5.5 415 0x80000014 0x005ccd
Router Link States (Area 3)
Link ID ADV Router Age Seq# Checksum Link count
3.3.3.3 3.3.3.3 1113 0x80000007 0x00ac9a 0
Net Link States (Area 3)
Link ID ADV Router Age Seq# Checksum
10.4.0.1 3.3.3.3 764 0x80000006 0x003b1d
Router4#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks
O IA 10.1.0.0/24 [110/2] via 10.3.0.1, 02:46:14, GigabitEthernet0/1
O IA 10.2.0.0/24 [110/3] via 10.3.0.1, 02:46:14, GigabitEthernet0/1
C 10.3.0.0/24 is directly connected, GigabitEthernet0/1
L 10.3.0.2/32 is directly connected, GigabitEthernet0/1
C 10.4.0.0/24 is directly connected, GigabitEthernet0/0
L 10.4.0.1/32 is directly connected, GigabitEthernet0/0
O IA 10.5.0.0/24 [110/2] via 10.4.0.2, 02:11:46, GigabitEthernet0/0
Router5
Router5#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
6.6.6.6 1 FULL/DR 00:00:31 10.5.0.2 GigabitEthernet0/1
2.2.2.2 0 FULL/ - 00:00:31 10.3.0.1 OSPF_VL0
3.3.3.3 1 FULL/BDR 00:00:31 10.4.0.1 GigabitEthernet0/0
Router5#show ip ospf database
OSPF Router with ID (5.5.5.5) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
5.5.5.5 5.5.5.5 1059 0x80000005 0x009874 1
2.2.2.2 2.2.2.2 487 0x8000000b 0x00e604 2
1.1.1.1 1.1.1.1 481 0x8000000b 0x0079af 1
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.1.0.2 2.2.2.2 487 0x80000005 0x001b1b
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.4.0.0 5.5.5.5 1069 0x8000000e 0x0030fe
10.3.0.0 5.5.5.5 1059 0x8000000f 0x0044e9
10.5.0.0 5.5.5.5 739 0x80000010 0x00200c
10.2.0.0 1.1.1.1 1268 0x80000006 0x00d078
10.3.0.0 2.2.2.2 1168 0x8000000a 0x009ea1
10.4.0.0 2.2.2.2 1142 0x8000000b 0x009aa2
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link count
5.5.5.5 5.5.5.5 485 0x8000000a 0x00946e 1
3.3.3.3 3.3.3.3 486 0x8000000d 0x001fc4 2
2.2.2.2 2.2.2.2 481 0x8000000a 0x0057c6 1
Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.4.0.2 5.5.5.5 1076 0x80000005 0x001739
10.3.0.2 3.3.3.3 486 0x80000006 0x003b8b
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.5.0.0 5.5.5.5 739 0x80000013 0x001a0f
10.1.0.0 2.2.2.2 1175 0x8000000b 0x00b48c
10.2.0.0 2.2.2.2 1175 0x8000000c 0x00b08d
10.1.0.0 5.5.5.5 471 0x80000014 0x005ccd
Router Link States (Area 3)
Link ID ADV Router Age Seq# Checksum Link count
5.5.5.5 5.5.5.5 486 0x8000000c 0x009768 1
6.6.6.6 6.6.6.6 485 0x80000008 0x005e9d 1
Net Link States (Area 3)
Link ID ADV Router Age Seq# Checksum
10.5.0.2 6.6.6.6 679 0x80000005 0x00330c
Summary Net Link States (Area 3)
Link ID ADV Router Age Seq# Checksum
10.1.0.0 5.5.5.5 1040 0x80000010 0x0064c9
Router5#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks
O 10.1.0.0/24 [110/3] via 10.4.0.1, 01:38:19, GigabitEthernet0/0
O IA 10.2.0.0/24 [110/4] via 10.4.0.1, 01:38:09, GigabitEthernet0/0
O 10.3.0.0/24 [110/2] via 10.4.0.1, 02:08:15, GigabitEthernet0/0
C 10.4.0.0/24 is directly connected, GigabitEthernet0/0
L 10.4.0.2/32 is directly connected, GigabitEthernet0/0
C 10.5.0.0/24 is directly connected, GigabitEthernet0/1
L 10.5.0.1/32 is directly connected, GigabitEthernet0/1
Router6
Router6#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
5.5.5.5 1 FULL/BDR 00:00:37 10.5.0.1 GigabitEthernet0/1
Router6#show ip ospf database
OSPF Router with ID (6.6.6.6) (Process ID 1)
Router Link States (Area 3)
Link ID ADV Router Age Seq# Checksum Link count
6.6.6.6 6.6.6.6 520 0x80000008 0x005e9d 1
5.5.5.5 5.5.5.5 522 0x8000000c 0x009768 1
Net Link States (Area 3)
Link ID ADV Router Age Seq# Checksum
10.5.0.2 6.6.6.6 714 0x80000005 0x00330c
Summary Net Link States (Area 3)
Link ID ADV Router Age Seq# Checksum
10.1.0.0 5.5.5.5 1076 0x80000010 0x0064c9
Router6#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O IA 10.1.0.0/24 [110/4] via 10.5.0.1, 02:12:20, GigabitEthernet0/1
C 10.5.0.0/24 is directly connected, GigabitEthernet0/1
L 10.5.0.2/32 is directly connected, GigabitEthernet0/1
You can also used “show ip route ospf” command for displaying only OSPF routes like below:
Router1#show ip route ospf
10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks
O IA 10.3.0.0 [110/2] via 10.1.0.2, 02:14:52, GigabitEthernet0/0
O IA 10.4.0.0 [110/3] via 10.1.0.2, 02:14:52, GigabitEthernet0/0
O IA 10.5.0.0 [110/4] via 10.1.0.2, 02:14:52, GigabitEthernet0/0
Lastly, let’s check the virtual-links.
Router2#show ip ospf virtual-links
Virtual Link OSPF_VL0 to router 5.5.5.5 is up
Run as demand circuit
Transit area 2, via interface GigabitEthernet0/1, Cost of using 2
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:09
Adjacency State FULL
Index 1/2, retransmission queue length 0, number of retransmission 0
First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
Last retransmission scan length is 0, maximum is 0
Last retransmission scan time is 0 msec, maximum is 0 msec
Router5#show ip ospf virtual-links
Virtual Link OSPF_VL0 to router 2.2.2.2 is up
Run as demand circuit
Transit area 2, via interface GigabitEthernet0/0, Cost of using 2
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:00
Adjacency State FULL
Index 1/2, retransmission queue length 0, number of retransmission 0
First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
Last retransmission scan length is 0, maximum is 0
Last retransmission scan time is 0 msec, maximum is 0 msec
In this post, we have talked about Standard OSPF Areas and Backbone Areas, beside Virtual-Links. We focused on configuration mostly. I hope this post will be helpful for you.
In the next post we will focus on other OSPF Area Types. Keep on, IPcisco.com ;)
You can DOWNLOAD the Packet Tracer example with .pkt format HERE.
You can download “Packet Tracer” in Tools section.
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