Lab 90 - BGP Filtering

Pada lab ini kita akan belajar melakukan filtering pada BGP menggunakan access list dan route map. Berikut topologi yang akan kita gunakan pada lab ini

Gambar 1 Topologi jaringan BGP

Kita akan konfigurasi EBGP Peering antara ketiga router diatas, selanjutnya kita akan membuat beberapa IP Loopback di R1 yang nantinya akan kita filter. Oke langsung aja ya..

R1(config)#int e0/0
R1(config-if)#no sh
R1(config-if)#ip add 12.12.12.1 255.255.255.0

R1(config-if)#int l0
R1(config-if)#ip add 1.1.1.1 255.255.255.255

R1(config-if)#int l1
R1(config-if)#ip add 1.1.1.2 255.255.255.255

R1(config-if)#int l2
R1(config-if)#ip add 1.1.1.3 255.255.255.255

R1(config-if)#int l3
R1(config-if)#ip add 1.1.1.4 255.255.255.255

R1(config-if)#int l4
R1(config-if)#ip add 1.1.1.5 255.255.255.255

R1(config-if)#int l5
R1(config-if)#ip add 1.1.1.6 255.255.255.255

R1(config-if)#router bgp 1
R1(config-router)#neighbor 12.12.12.2 remote-as 2
R1(config-router)#net 1.1.1.1 mask 255.255.255.255 
R1(config-router)#net 1.1.1.2 mask 255.255.255.255
R1(config-router)#net 1.1.1.3 mask 255.255.255.255
R1(config-router)#net 1.1.1.4 mask 255.255.255.255
R1(config-router)#net 1.1.1.5 mask 255.255.255.255
R1(config-router)#net 1.1.1.6 mask 255.255.255.255

R2(config)#int e0/0
R2(config-if)#no sh
R2(config-if)#ip add 12.12.12.2 255.255.255.0

R2(config-if)#int e0/1
R2(config-if)#ip add 23.23.23.2 255.255.255.0

R2(config)#router bgp 2
R2(config-router)#neighbor 12.12.12.1 remote-as 1
R2(config-router)#neighbor 23.23.23.3 remote-as 3

R3(config)#int e0/0
R3(config-if)#no sh
R3(config-if)#ip add 23.23.23.3 255.255.255.0

R3(config-if)#router bgp 3
R3(config-router)#neighbor 23.23.23.2 remote-as 2

Untuk pengujian, kita coba lihat tabel routing di R2 dan R3. Pastikan kedua router ini punya informasi tentang seluruh IP Loopback R1

R2(config-router)#do sh ip ro
      1.0.0.0/32 is subnetted, 6 subnets
B        1.1.1.1 [20/0] via 12.12.12.1, 00:02:10
B        1.1.1.2 [20/0] via 12.12.12.1, 00:02:10
B        1.1.1.3 [20/0] via 12.12.12.1, 00:02:10
B        1.1.1.4 [20/0] via 12.12.12.1, 00:02:10
B        1.1.1.5 [20/0] via 12.12.12.1, 00:02:10
B        1.1.1.6 [20/0] via 12.12.12.1, 00:02:10
      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

      1.0.0.0/32 is subnetted, 6 subnets
B        1.1.1.1 [20/0] via 23.23.23.2, 00:02:12
B        1.1.1.2 [20/0] via 23.23.23.2, 00:02:12
B        1.1.1.3 [20/0] via 23.23.23.2, 00:02:12
B        1.1.1.4 [20/0] via 23.23.23.2, 00:02:12
B        1.1.1.5 [20/0] via 23.23.23.2, 00:02:12
B        1.1.1.6 [20/0] via 23.23.23.2, 00:02:12
      23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        23.23.23.0/24 is directly connected, Ethernet0/0

Sip2 R2 dan R3 sudah punya informasi tentang seluruh IP Loopback R1. Sekarang kita coba lakukan filtering ya.. tujuan kita biar R2 dan R3 gak punya informasi tentang IP yang genap

R1(config)#access-list 1 deny 1.1.1.0 0.0.0.254
R1(config)#access-list 1 permit any 

R1(config)#route-map FILTERING
R1(config-route-map)#match ip address 1

R1(config-route-map)#router bgp 1
R1(config-router)#neighbor 12.12.12.2 route-map FILTERING out

R1(config-router)#do cle ip bgp *

Oke sekarang kita coba lihat lagi tabel routing di R2 dan R3

R2(config-router)#do sh ip ro 

      1.0.0.0/32 is subnetted, 3 subnets
B        1.1.1.1 [20/0] via 12.12.12.1, 00:00:44
B        1.1.1.3 [20/0] via 12.12.12.1, 00:00:44
B        1.1.1.5 [20/0] via 12.12.12.1, 00:00:44
      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

      1.0.0.0/32 is subnetted, 3 subnets
B        1.1.1.1 [20/0] via 23.23.23.2, 00:01:35
B        1.1.1.3 [20/0] via 23.23.23.2, 00:01:35
B        1.1.1.5 [20/0] via 23.23.23.2, 00:01:35
      23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        23.23.23.0/24 is directly connected, Ethernet0/0

Juozzzz kita udah berhasil melakukan filtering..