A routing example of 3 area’s created with GNS3.
Show running-configs of the OSPF section of all 7 routers
R1#show running-config | section ospf router ospf 1 network 10.0.0.0 0.0.255.255 area 0 R2#show running-config | section ospf router ospf 1 network 10.0.0.0 0.0.255.255 area 0 network 192.0.0.0 0.255.255.255 area 1 R3#show running-config | section ospf router ospf 1 network 10.0.0.0 0.255.255.255 area 0 network 192.168.0.0 0.0.255.255 area 2 R4#show running-config | section ospf router ospf 1 network 172.16.0.0 0.0.255.255 area 1 network 192.168.0.0 0.0.255.255 area 1 R5#show running-config | section ospf router ospf 1 network 172.16.0.0 0.0.255.255 area 1 network 192.168.0.0 0.0.255.255 area 1 R6#show running-config | section ospf router ospf 1 network 172.16.0.0 0.0.255.255 area 2 network 192.168.0.0 0.0.255.255 area 2 R7#show running-config | section ospf router ospf 1 network 172.16.0.0 0.0.255.255 area 2 network 192.168.0.0 0.0.255.255 area 2
Show commands of R1
show ip ospf neighbor
R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.100.3 1 FULL/DR 00:00:31 10.0.20.2 GigabitEthernet0/1 10.0.100.2 1 FULL/DR 00:00:38 10.0.10.2 GigabitEthernet0/0
show ip ospf interface
R1#show ip ospf interface
Loopback0 is up, line protocol is up
Internet Address 10.0.100.1/32, Area 0, Attached via Network Statement
Process ID 1, Router ID 10.0.100.1, Network Type LOOPBACK, Cost: 1
Topology-MTID Cost Disabled Shutdown Topology Name
0 1 no no Base
Loopback interface is treated as a stub Host
GigabitEthernet0/1 is up, line protocol is up
Internet Address 10.0.20.1/24, Area 0, Attached via Network Statement
Process ID 1, Router ID 10.0.100.1, Network Type BROADCAST, Cost: 1
Topology-MTID Cost Disabled Shutdown Topology Name
0 1 no no Base
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 10.0.100.3, Interface address 10.0.20.2
Backup Designated router (ID) 10.0.100.1, Interface address 10.0.20.1
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:02
Supports Link-local Signaling (LLS)
Cisco NSF helper support enabled
IETF NSF helper support enabled
Index 1/2/2, flood queue length 0
Next 0x0(0)/0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 2
Last flood scan time is 0 msec, maximum is 8 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 10.0.100.3 (Designated Router)
Suppress hello for 0 neighbor(s)
GigabitEthernet0/0 is up, line protocol is up
Internet Address 10.0.10.1/24, Area 0, Attached via Network Statement
Process ID 1, Router ID 10.0.100.1, Network Type BROADCAST, Cost: 1
Topology-MTID Cost Disabled Shutdown Topology Name
0 1 no no Base
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 10.0.100.2, Interface address 10.0.10.2
Backup Designated router (ID) 10.0.100.1, Interface address 10.0.10.1
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:00
Supports Link-local Signaling (LLS)
Cisco NSF helper support enabled
IETF NSF helper support enabled
Index 1/1/1, flood queue length 0
Next 0x0(0)/0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 4
Last flood scan time is 0 msec, maximum is 1 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 10.0.100.2 (Designated Router)
Suppress hello for 0 neighbor(s)
show ip protocols
R1#show ip protocols
*** IP Routing is NSF aware ***
Routing Protocol is "application"
Sending updates every 0 seconds
Invalid after 0 seconds, hold down 0, flushed after 0
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Maximum path: 32
Routing for Networks:
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 4)
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 10.0.100.1
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
10.0.0.0 0.0.255.255 area 0
Routing Information Sources:
Gateway Distance Last Update
Gateway Distance Last Update
10.0.100.2 110 00:05:30
10.0.100.3 110 00:05:20
Distance: (default is 110)
show ip route
R1#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
i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks
C 10.0.10.0/24 is directly connected, GigabitEthernet0/0
L 10.0.10.1/32 is directly connected, GigabitEthernet0/0
C 10.0.20.0/24 is directly connected, GigabitEthernet0/1
L 10.0.20.1/32 is directly connected, GigabitEthernet0/1
C 10.0.100.1/32 is directly connected, Loopback0
O 10.0.100.2/32 [110/2] via 10.0.10.2, 00:05:34, GigabitEthernet0/0
O 10.0.100.3/32 [110/2] via 10.0.20.2, 00:05:24, GigabitEthernet0/1
172.16.0.0/24 is subnetted, 4 subnets
O IA 172.16.100.0 [110/3] via 10.0.10.2, 00:05:34, GigabitEthernet0/0
O IA 172.16.101.0 [110/3] via 10.0.10.2, 00:05:34, GigabitEthernet0/0
O IA 172.16.200.0 [110/3] via 10.0.20.2, 00:05:24, GigabitEthernet0/1
O IA 172.16.201.0 [110/3] via 10.0.20.2, 00:05:24, GigabitEthernet0/1
O IA 192.168.100.0/24 [110/2] via 10.0.10.2, 00:05:34, GigabitEthernet0/0
O IA 192.168.101.0/24 [110/2] via 10.0.10.2, 00:05:34, GigabitEthernet0/0
O IA 192.168.200.0/24 [110/2] via 10.0.20.2, 00:05:24, GigabitEthernet0/1
O IA 192.168.201.0/24 [110/2] via 10.0.20.2, 00:05:24, GigabitEthernet0/1
show ip ospf database
R1#show ip ospf database
OSPF Router with ID (10.0.100.1) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
10.0.100.1 10.0.100.1 339 0x80000004 0x002135 3
10.0.100.2 10.0.100.2 345 0x80000004 0x00148C 2
10.0.100.3 10.0.100.3 344 0x80000004 0x00DBAD 2
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.0.10.2 10.0.100.2 345 0x80000001 0x00ECE6
10.0.20.2 10.0.100.3 344 0x80000001 0x008245
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
172.16.100.0 10.0.100.2 359 0x80000001 0x00A207
172.16.101.0 10.0.100.2 349 0x80000001 0x009711
172.16.200.0 10.0.100.3 342 0x80000001 0x004CF7
172.16.201.0 10.0.100.3 332 0x80000001 0x004102
192.168.100.0 10.0.100.2 418 0x80000001 0x006C91
192.168.101.0 10.0.100.2 418 0x80000001 0x00619B
192.168.200.0 10.0.100.3 399 0x80000001 0x001682
192.168.201.0 10.0.100.3 399 0x80000001 0x000B8C
show ip ospf neighbor of all 7 routers
R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.100.3 1 FULL/DR 00:00:36 10.0.20.2 GigabitEthernet0/1 10.0.100.2 1 FULL/DR 00:00:39 10.0.10.2 GigabitEthernet0/0 R2#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.100.1 1 FULL/BDR 00:00:33 10.0.10.1 GigabitEthernet0/0 10.0.100.5 1 FULL/BDR 00:00:34 192.168.101.2 GigabitEthernet0/2 10.0.100.4 1 FULL/BDR 00:00:30 192.168.100.2 GigabitEthernet0/1 R3#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.100.1 1 FULL/BDR 00:00:33 10.0.20.1 GigabitEthernet0/0 10.0.100.7 1 FULL/BDR 00:00:36 192.168.201.2 GigabitEthernet0/2 10.0.100.6 1 FULL/BDR 00:00:34 192.168.200.2 GigabitEthernet0/1 R4#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.100.2 1 FULL/DR 00:00:38 192.168.100.1 GigabitEthernet0/0 R5#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.100.2 1 FULL/DR 00:00:36 192.168.101.1 GigabitEthernet0/0 R6#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.100.3 1 FULL/DR 00:00:37 192.168.200.1 GigabitEthernet0/0 R7#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.100.3 1 FULL/DR 00:00:35 192.168.201.1 GigabitEthernet0/0