Day 3 - OSPF Virtual Link

Pada ospf, bila diinginkan menggunakan area lain selain Area 0, maka area tersebut harus terhubung dengan Area 0.

Bila ternyata kondisinya ada area yang tidak tersambung dengan Area 0, maka hasilnya routing table nya tidak lengkap karena tidak mau untuk saling berbagi informasi routing table nya.

Lab kali ini kita akan membahas bagaimana membuat virtual link pada routing OSPF sebagai salah satu solusi untuk masalah diatas.

Lab 1 - OSPF Virtual Link

Topologi yang digunakan adalah sbb :

 
Skenarionya adalah menyambungkan area 3 di router R3 ke area 0 di router R1.


Konfigurasi R1 :

interface Loopback0
 ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet0/0
 ip address 12.12.12.1 255.255.255.0
!

router ospf 1
 router-id 1.1.1.1
 log-adjacency-changes
 area 1 virtual-link 2.2.2.2
 network 1.1.1.1 0.0.0.0 area 0
 network 12.12.12.1 0.0.0.0 area 1

Konfigurasi R2 :
interface Loopback0
 ip address 2.2.2.2 255.255.255.255
!
interface FastEthernet0/0
 ip address 12.12.12.2 255.255.255.0
!
interface Serial0/0
 ip address 23.23.23.2 255.255.255.0
!
router ospf 2
 router-id 2.2.2.2
 log-adjacency-changes
 network 2.2.2.2 0.0.0.0 area 1
 network 12.12.12.2 0.0.0.0 area 1
 network 23.23.23.2 0.0.0.0 area 2


Konfigurasi R3 :

interface Loopback0
  ip address 3.3.3.3 255.255.255.255
!
interface Serial0/0
 ip address 23.23.23.3 255.255.255.0
!
router ospf 3
 router-id 3.3.3.3
 log-adjacency-changes
 network 3.3.3.3 0.0.0.0 area 3
 network 23.23.23.3 0.0.0.0 area 2

Hasil cek routing table pada kondisi awal :

R1(config-router)#do sh ip route
Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
C       1.1.1.1 is directly connected, Loopback0
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/11] via 12.12.12.2, 00:08:02, FastEthernet0/0
     12.0.0.0/24 is subnetted, 1 subnets
C       12.12.12.0 is directly connected, FastEthernet0/0

R2(config-router)#do sh ip route
Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
O IA    1.1.1.1 [110/11] via 12.12.12.1, 00:00:47, FastEthernet0/0
     2.0.0.0/32 is subnetted, 1 subnets
C       2.2.2.2 is directly connected, Loopback0
     23.0.0.0/24 is subnetted, 1 subnets
C       23.23.23.0 is directly connected, Serial0/0
     12.0.0.0/24 is subnetted, 1 subnets
C       12.12.12.0 is directly connected, FastEthernet0/0

R3(config-router)#do sh ip route
Gateway of last resort is not set

     3.0.0.0/32 is subnetted, 1 subnets
C       3.3.3.3 is directly connected, Loopback0
     23.0.0.0/24 is subnetted, 1 subnets
C       23.23.23.0 is directly connected, Serial0/0

Terlihat bahwa pada router R1, R2 dan R3 tidak lengkap menerima routing dari masing - masing area.
Karena yang terhubung ke Area 0 hanya R1, sedangkan R2 dan R3 tidak.

Sekarang kita coba buat virtual link pada ketiga area tersebut.
Pertama kita buat virtual link antara R1 dan R2 terlebih dahulu.

R1(config)#router ospf 1
R1(config-router)#area 1 virtual-link 2.2.2.2

R2(config)#router ospf 2
R2(config-router)#area 1 virtual-link 1.1.1.1

Kita cek kembali routing table di R1 dan R2 :

R1(config-router)#do sh ip route
Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
C       1.1.1.1 is directly connected, Loopback0
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/11] via 12.12.12.2, 00:18:12, FastEthernet0/0
     23.0.0.0/24 is subnetted, 1 subnets
O IA    23.23.23.0 [110/74] via 12.12.12.2, 00:05:43, FastEthernet0/0
     12.0.0.0/24 is subnetted, 1 subnets
C       12.12.12.0 is directly connected, FastEthernet0/0

R2(config-router)#do sh ip route
Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
O       1.1.1.1 [110/11] via 12.12.12.1, 00:06:29, FastEthernet0/0
     2.0.0.0/32 is subnetted, 1 subnets
C       2.2.2.2 is directly connected, Loopback0
     23.0.0.0/24 is subnetted, 1 subnets
C       23.23.23.0 is directly connected, Serial0/0
     12.0.0.0/24 is subnetted, 1 subnets
C       12.12.12.0 is directly connected, FastEthernet0/0

Terlihat bahwa di router R1 sudah menerima routing dari Area 2 (23.23.23.0/24)
Tapi belum dapat menerima routing dari Area 3.
Sekarang kita buat virtual link antara R2 dan R3 :

R2(config)#router ospf 2

R2(config-router)#area 2 virtual-link 3.3.3.3
R2(config-router)#
*Mar  1 00:22:42.639: %OSPF-5-ADJCHG: Process 2, Nbr 3.3.3.3 on OSPF_VL3 from LOADING to FULL, Loading Done

R3(config)#router ospf 3

R3(config-router)#area 2 virtual-link 2.2.2.2
R3(config-router)#
*Mar  1 00:22:42.407: %OSPF-5-ADJCHG: Process 3, Nbr 2.2.2.2 on OSPF_VL1 from LOADING to FULL, Loading Done

Kita coba cek lagi routing table di R1, R2 dan R3 :

R1(config-router)#do sh ip route
Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
C       1.1.1.1 is directly connected, Loopback0
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/11] via 12.12.12.2, 00:23:23, FastEthernet0/0
     3.0.0.0/32 is subnetted, 1 subnets
O IA    3.3.3.3 [110/75] via 12.12.12.2, 00:01:23, FastEthernet0/0
     23.0.0.0/24 is subnetted, 1 subnets
O IA    23.23.23.0 [110/74] via 12.12.12.2, 00:10:54, FastEthernet0/0
     12.0.0.0/24 is subnetted, 1 subnets
C       12.12.12.0 is directly connected, FastEthernet0/0

R2(config-router)#do sh ip route
Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
O       1.1.1.1 [110/11] via 12.12.12.1, 00:11:15, FastEthernet0/0
     2.0.0.0/32 is subnetted, 1 subnets
C       2.2.2.2 is directly connected, Loopback0
     3.0.0.0/32 is subnetted, 1 subnets
O IA    3.3.3.3 [110/65] via 23.23.23.3, 00:01:44, Serial0/0
     23.0.0.0/24 is subnetted, 1 subnets
C       23.23.23.0 is directly connected, Serial0/0
     12.0.0.0/24 is subnetted, 1 subnets
C       12.12.12.0 is directly connected, FastEthernet0/0

R3(config-router)#do sh ip route
Gateway of last resort is not set

     1.0.0.0/32 is subnetted, 1 subnets
O       1.1.1.1 [110/75] via 23.23.23.2, 00:13:30, Serial0/0
     2.0.0.0/32 is subnetted, 1 subnets
O IA    2.2.2.2 [110/65] via 23.23.23.2, 00:13:30, Serial0/0
     3.0.0.0/32 is subnetted, 1 subnets
C       3.3.3.3 is directly connected, Loopback0
     23.0.0.0/24 is subnetted, 1 subnets
C       23.23.23.0 is directly connected, Serial0/0
     12.0.0.0/24 is subnetted, 1 subnets
O IA    12.12.12.0 [110/74] via 23.23.23.2, 00:13:30, Serial0/0

Hasil cek ip ospf neighbor di R1, R2 dan R3 :

R1(config-router)#do sh ip ospf neighbor
Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           0   FULL/  -           -        12.12.12.2      OSPF_VL1
2.2.2.2           1   FULL/DR         00:00:30    12.12.12.2      FastEthernet0/0

R2(config-router)#do sh ip ospf neighbor
Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           0   FULL/  -           -        23.23.23.3      OSPF_VL3
1.1.1.1           0   FULL/  -           -        12.12.12.1      OSPF_VL2
1.1.1.1           1   FULL/BDR        00:00:37    12.12.12.1      FastEthernet0/0
3.3.3.3           0   FULL/  -        00:00:37    23.23.23.3      Serial0/0

R3(config-router)#do sh ip ospf neighbor
Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           0   FULL/  -           -        23.23.23.2      OSPF_VL1
2.2.2.2           0   FULL/  -        00:00:34    23.23.23.2      Serial0/0
 
Kita coba ping dari R1 ke IP Loopback R3 dan dari R3 ke IP Loopback R1 :

R1(config-router)#do ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/24/28 ms

R3(config-router)#do ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/25/44 ms

Hasil ping sudah sukses :)