OSPF - Filtering LSA-Type 3 - Coretan Buruh IT

Postinan kali ini adalah membahas cara konfigurasi dan filtering LSA type 3 yang beredar di router R1 atau area 0 artinya untuk mengijinkan route mana saja yg diijinkan dan mana route mana yg yg tidak diijinkan., tujuannya dalah untuk melakukan kontrol terhadap network OSPF.

Kondisi awal, setelah konfigurasi ip masing-masing dan advertise network sesuai area masing.

Verifkasi dimasing-masing router pada Routing Table

R1
R1#show ip ro
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
23.0.0.0/24 is subnetted, 1 subnets
O IA 23.23.23.0 [110/20] via 12.12.12.2, 00:00:03, FastEthernet0/0
192.168.4.0/32 is subnetted, 1 subnets
O IA 192.168.4.1 [110/21] via 12.12.12.2, 00:00:03, FastEthernet0/0
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet0/0
192.168.1.0/32 is subnetted, 1 subnets
O IA 192.168.1.1 [110/21] via 12.12.12.2, 00:00:04, FastEthernet0/0
192.168.2.0/32 is subnetted, 1 subnets
O IA 192.168.2.1 [110/21] via 12.12.12.2, 00:00:04, FastEthernet0/0
192.168.3.0/32 is subnetted, 1 subnets
O IA 192.168.3.1 [110/21] via 12.12.12.2, 00:00:06, FastEthernet0/0
R1#

R2#show ip ro

1.0.0.0/32 is subnetted, 1 subnets

O 1.1.1.1 [110/11] via 12.12.12.1, 00:08:26, 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, FastEthernet0/1

192.168.4.0/32 is subnetted, 1 subnets

O 192.168.4.1 [110/11] via 23.23.23.3, 00:08:51, FastEthernet0/1

12.0.0.0/24 is subnetted, 1 subnets

C 12.12.12.0 is directly connected, FastEthernet0/0

192.168.1.0/32 is subnetted, 1 subnets

O 192.168.1.1 [110/11] via 23.23.23.3, 00:08:52, FastEthernet0/1

192.168.2.0/32 is subnetted, 1 subnets

O 192.168.2.1 [110/11] via 23.23.23.3, 00:08:53, FastEthernet0/1

192.168.3.0/32 is subnetted, 1 subnets

O 192.168.3.1 [110/11] via 23.23.23.3, 00:08:53, FastEthernet0/1

R2#

R3#show ip ro

1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/21] via 23.23.23.2, 00:09:32, FastEthernet0/1
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, FastEthernet0/1
C 192.168.4.0/24 is directly connected, Loopback4
12.0.0.0/24 is subnetted, 1 subnets
O IA 12.12.12.0 [110/20] via 23.23.23.2, 00:09:57, FastEthernet0/1
C 192.168.1.0/24 is directly connected, Loopback1
C 192.168.2.0/24 is directly connected, Loopback2
C 192.168.3.0/24 is directly connected, Loopback3

R3#

Karena R1 menerima LSA type 3 maka R1 memiliki 5 intra area routes yt:

network 23.23.23.3 0.0.0.0 area 1
network 192.168.1.0 0.0.0.255 area 1
network 192.168.2.0 0.0.0.255 area 1
network 192.168.3.0 0.0.0.255 area 1
network 192.168.4.0 0.0.0.255 area 1

Misalkan suatu saat kita diharuskan melakukan konfigurasi agar R1 yang berada di area 0 tidak bisa mengengenali network 192.168.1.0/24, maka kt bisa memanfaatkan fitur filtering LSA type 3.

Perintahnya kita ketik di R2 ;

R2(config)#ip prefix-list ke-area_0 deny 192.168.1.0/24

R2(config)#ip prefix-list ke-area_0 permit 0.0.0.0/0 le 32

R2(config)#

R2(config)#router ospf 2

R2(config-router)#area 0 filter-list prefix ke-area_0 in