Lab 70 - OSPF Filtering (Perbolehkan IP Ganjil)

Sebelumnya kita telah belajar melakukan filtering untuk Memperbolehkan IP Genap. Selanjutnya pada lab ini kita akan belajar melakukan filtering pada OSPF untuk memperbolehkan IP Ganjil saja. Berikut topologi yang akan kita gunakan pada lab ini

Gambar 1 Topologi jaringan OSPF

Kita hapus dulu konfigurasi filtering yang kita lakukan sebelumnya

R2(config)#router ospf 1
R2(config-router)#no distribute-list 1 in

R3(config)#router ospf 1
R3(config-router)#no distribute-list 1 in

Pastikan tabel routing di R2 dan R3 sudah lengkap lagi

R2(config-router)#do sh ip ro 

      11.0.0.0/32 is subnetted, 6 subnets
O        11.11.11.1 [110/11] via 12.12.12.1, 00:00:48, Ethernet0/0
O        11.11.11.2 [110/11] via 12.12.12.1, 00:00:48, Ethernet0/0
O        11.11.11.3 [110/11] via 12.12.12.1, 00:00:48, Ethernet0/0
O        11.11.11.4 [110/11] via 12.12.12.1, 00:00:48, Ethernet0/0
O        11.11.11.5 [110/11] via 12.12.12.1, 00:00:48, Ethernet0/0
O        11.11.11.6 [110/11] via 12.12.12.1, 00:00:48, Ethernet0/0
      12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        12.12.12.0/24 is directly connected, Ethernet0/0
      23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        23.23.23.0/24 is directly connected, Ethernet0/1

R3(config-router)#do sh ip ro

      11.0.0.0/32 is subnetted, 6 subnets
O        11.11.11.1 [110/21] via 23.23.23.2, 00:00:51, Ethernet0/0
O        11.11.11.2 [110/21] via 23.23.23.2, 00:00:51, Ethernet0/0
O        11.11.11.3 [110/21] via 23.23.23.2, 00:00:51, Ethernet0/0
O        11.11.11.4 [110/21] via 23.23.23.2, 00:00:51, Ethernet0/0
O        11.11.11.5 [110/21] via 23.23.23.2, 00:00:51, Ethernet0/0
O        11.11.11.6 [110/21] via 23.23.23.2, 00:00:51, Ethernet0/0
      12.0.0.0/24 is subnetted, 1 subnets
O        12.12.12.0 [110/20] via 23.23.23.2, 00:00:51, Ethernet0/0
      23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        23.23.23.0/24 is directly connected, Ethernet0/0

Sekarang kita konfigurasikan filtering agar R3 hanya memiliki informasi tentang IP Ganjil saja

R3(config)#access-list 2 permit 0.0.0.1 255.255.255.254

R3(config)#router ospf 1
R3(config-router)#distribute-list 2 in

Untuk pengujian kita coba lihat tabel routing di R3

R3(config-router)#do sh ip ro

      11.0.0.0/32 is subnetted, 3 subnets
O        11.11.11.1 [110/21] via 23.23.23.2, 00:02:25, Ethernet0/0
O        11.11.11.3 [110/21] via 23.23.23.2, 00:02:25, Ethernet0/0
O        11.11.11.5 [110/21] via 23.23.23.2, 00:02:25, Ethernet0/0
      23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        23.23.23.0/24 is directly connected, Ethernet0/0

Perhatikan bahwa saat ini R3 hanya memiliki informasi tentang IP Ganjil saja, sesuai dengan yang kita inginkan