OSPF Lab 7

Tasks:

1. Enable OSPF on the routers according to the diagram.
Do use ip ospf network command on R1.
DR election should not occurred.

2. Enable MD5 Authentication on area 0. Use the key number 2 and password MD5Pwd.
Use area authentication command. Do authenticate the adjacency between R1 and R3.

3. R4 is stub router. It does need detailed information about the network topology.
Configure R1 and R4 to fulfill the requirement .

4. The route sent to R4 should be seen on R4 with a cost of 3.
Do not use any configuration level command.

5. Configure R2 so that R5 cannot reach the subnet 111.111.4.0/24.

Lab Diagram:

NB: Click here to download the .net file and the initial configuration files.

Solutions:

Task 1

R1:
router ospf 1
network 111.111.12.1 0.0.0.0 area 0
network 111.111.13.1 0.0.0.0 area 0
network 111.111.14.1 0.0.0.0 area 1

R2:
router ospf 1
network 111.111.12.2 0.0.0.0 area 0
network 111.111.25.2 0.0.0.0 area 5

interface Serial1/0
ip ospf network point-to-point

R3:
router ospf 1
network 111.111.3.3 0.0.0.0 area 3
network 111.111.13.3 0.0.0.0 area 0

interface Serial1/0
ip ospf network point-to-point

R4:
router ospf 1
network 0.0.0.0 255.255.255.255 area 1

R5:
router ospf 1
network 0.0.0.0 255.255.255.255 area 5

Verification:

R1# sh ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
111.111.13.3 0 FULL/ – 00:00:38 111.111.13.3 Serial1/0.13
111.111.25.2 0 FULL/ – 00:00:34 111.111.12.2 Serial1/0.12
111.111.14.4 1 FULL/BDR 00:00:31 111.111.14.4 FastEthernet0/0

R1#sh ip route ospf
111.0.0.0/24 is subnetted, 7 subnets
O IA 111.111.3.0 [110/65] via 111.111.13.3, 00:01:53, Serial1/0.13
O 111.111.4.0 [110/2] via 111.111.14.4, 00:01:53, FastEthernet0/0
O IA 111.111.5.0 [110/66] via 111.111.12.2, 00:01:43, Serial1/0.12
O IA 111.111.25.0 [110/65] via 111.111.12.2, 00:01:48, Serial1/0.12

R2# sh ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
111.111.14.1 0 FULL/ – 00:00:32 111.111.12.1 Serial1/0
111.111.25.5 1 FULL/BDR 00:00:36 111.111.25.5 FastEthernet0/0

R2#sh ip route ospf
111.0.0.0/24 is subnetted, 7 subnets
O IA 111.111.3.0 [110/129] via 111.111.12.1, 00:01:40, Serial1/0
O IA 111.111.4.0 [110/66] via 111.111.12.1, 00:01:40, Serial1/0
O 111.111.5.0 [110/2] via 111.111.25.5, 00:01:40, FastEthernet0/0
O 111.111.13.0 [110/128] via 111.111.12.1, 00:02:39, Serial1/0
O IA 111.111.14.0 [110/65] via 111.111.12.1, 00:01:40, Serial1/0

R3# sh ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
111.111.14.1 0 FULL/ – 00:00:35 111.111.13.1 Serial1/0

R3#sh ip route ospf
111.0.0.0/24 is subnetted, 7 subnets
O IA 111.111.4.0 [110/66] via 111.111.13.1, 00:01:47, Serial1/0
O IA 111.111.5.0 [110/130] via 111.111.13.1, 00:01:37, Serial1/0
O 111.111.12.0 [110/128] via 111.111.13.1, 00:02:38, Serial1/0
O IA 111.111.14.0 [110/65] via 111.111.13.1, 00:01:52, Serial1/0
O IA 111.111.25.0 [110/129] via 111.111.13.1, 00:01:42, Serial1/0

R4#sh ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
111.111.14.1 1 FULL/DR 00:00:36 111.111.14.1 FastEthernet0/0

R4# sh ip route ospf
111.0.0.0/24 is subnetted, 7 subnets
O IA 111.111.3.0 [110/66] via 111.111.14.1, 00:01:54, FastEthernet0/0
O IA 111.111.5.0 [110/67] via 111.111.14.1, 00:01:34, FastEthernet0/0
O IA 111.111.12.0 [110/65] via 111.111.14.1, 00:01:54, FastEthernet0/0
O IA 111.111.13.0 [110/65] via 111.111.14.1, 00:01:54, FastEthernet0/0
O IA 111.111.25.0 [110/66] via 111.111.14.1, 00:01:34, FastEthernet0/0

R5# sh ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
111.111.25.2 1 FULL/DR 00:00:34 111.111.25.2 FastEthernet0/0

R5#sh ip route ospf
111.0.0.0/24 is subnetted, 7 subnets
O IA 111.111.3.0 [110/130] via 111.111.25.2, 00:01:25, FastEthernet0/0
O IA 111.111.4.0 [110/67] via 111.111.25.2, 00:01:25, FastEthernet0/0
O IA 111.111.12.0 [110/65] via 111.111.25.2, 00:01:25, FastEthernet0/0
O IA 111.111.13.0 [110/129] via 111.111.25.2, 00:01:25, FastEthernet0/0
O IA 111.111.14.0 [110/66] via 111.111.25.2, 00:01:25, FastEthernet0/0

Task 2

R1:
router ospf 1
area 0 authentication message-digest

interface Serial1/0.12 point-to-point
ip ospf message-digest-key 2 md5 MD5Pwd

!
interface Serial1/0.13 point-to-point
ip ospf authentication null

R2:
router ospf 1
area 0 authentication message-digest

interface Serial1/0
ip ospf message-digest-key 2 md5 MD5Pwd

verification:

R1#sh ip ospf int s1/0.12
Serial1/0.12 is up, line protocol is up
…. omitted output
Message digest authentication enabled
Youngest key id is 2

R2#sh ip ospf int s1/0
Serial1/0 is up, line protocol is up
…. omitted output
Message digest authentication enabled
Youngest key id is 2

Task 3

R1 and R4:
router ospf 1
area 1 stub

Verification:

R1#sh ip ospf 1 | begin Area 1
Area 1
Number of interfaces in this area is 1
It is a stub area
generates stub default route with cost 1

R4#sh ip ospf 1 | begin Area 1
Area 1
Number of interfaces in this area is 2
It is a stub area

Task 4

R1:
router ospf 1
area 1 stub no-summary
area 1 default-cost 2

Verification:

R4#sh ip route
Codes: 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

Gateway of last resort is 111.111.14.1 to network 0.0.0.0

111.0.0.0/24 is subnetted, 2 subnets
C 111.111.4.0 is directly connected, FastEthernet0/1
C 111.111.14.0 is directly connected, FastEthernet0/0
O*IA 0.0.0.0/0 [110/3] via 111.111.14.1, 00:00:24, FastEthernet0/0

Task 5

R2:
ip prefix-list R4_Prefix seq 5 deny 111.111.4.0/24
ip prefix-list R4_Prefix seq 10 permit 0.0.0.0/0 le 32

router ospf 1
area 5 filter-list prefix R4_Prefix in

Verification:

R5#show ip route 111.111.4.0
% Subnet not in table