EIGRP : Filtering Prefix-list

Sama seperti Filtering Distribute-list, cuma agak lebih kompleks dikit, karena kita bisa mengatur prefix apa aja yang bakal keluar atau masuk. fungsinya apa? sama aja, buat ngeringanin si Router.

Untuk caranya ada 2 macam lagee, yaitu in dan out. Biar paham langsung ke konfignya aja deh.

The Topology

Cara Pertama (in) :
Tambahin IP loopback di router 3 dulu, pake prefix nya beda beda ya, kenapa? karena kita bakalan filter sebagian prefix dari beberapa prefix yang sudah kita buat.

R3(config-if)#ip ad 3.3.3.17 255.255.255.240
R3(config-if)#int lo2
R3(config-if)#ip ad 3.3.3.9 255.255.255.248
R3(config-if)#int lo3
R3(config-if)#ip ad 3.3.3.5 255.255.255.252
R3(config-if)#int lo4
R3(config-if)#ip ad 3.3.3.33 255.255.255.224
R3(config-if)#int lo5
R3(config-if)#ip add 3.3.3.200 255.255.255.240

Buat rule-nya, dan rule yang mau saya buat akan memfilter IP Loopback yang prefixnya /27–29, jadi prefix yang bakal muncul cuma 30–32.

R2(config)#ip prefix-list PREFIX seq 10 deny 3.3.3.0/24 ge 27 le 29
R2(config)#ip prefix-list PREFIX seq 20 permit 0.0.0.0/0 le 32

• LE (Less than or Equal to): Milih dia dan dibawahnya, misal di contohkan 29, berarti dia bakal milih semuanya yang prefixnya di bawah si 29 termasuk si 29-nya juga. Jadi yang difilter adalah 27,28,29.
• GE (Greater than or Equal to): Milih dia dan diatasnya, contohnya ge 27, berarti dia bakal milih semua yang prefixnya diatasnya si 27. jadi yang difilter adalah 27,28.

Masukkin prefix-listnya ke EIGRP.

R2(config)#router eigrp 10
R2(config-router)#distribute-list prefix PREFIX in

Tunggu notif, kalo udah cek routing table.

R1(config-router)#
*Jun 26 14:29:27.366: %DUAL-5-NBRCHANGE: EIGRP-IPv4 10: Neighbor 11.11.11.2 (FastEthernet0/0) is resync: peer graceful-restart
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
D        2.2.2.2 [90/156160] via 11.11.11.2, 04:29:57, FastEthernet0/0
      3.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
D        3.3.3.3/32 [90/158720] via 11.11.11.2, 04:29:15, FastEthernet0/0
D        3.3.3.4/30 [90/158720] via 11.11.11.2, 03:52:37, FastEthernet0/0
      11.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        11.11.11.0/24 is directly connected, FastEthernet0/0
L        11.11.11.1/32 is directly connected, FastEthernet0/0
      22.0.0.0/24 is subnetted, 1 subnets
D        22.22.22.0 [90/30720] via 11.11.11.2, 04:30:03, FastEthernet0/0
R1(config-router)#

Done.

*Sebelumnya, jangan lupa untuk hapus Filter Prefix list yang ada di EIGRP dulu.

Cara Kedua (out) :
Sekarang kita akan memfilter prefix /28 kebawah, ga usah lama-lama langsung aja kita bikin rule prefix list-nya di router 3.

R3(config)#ip prefix-list Filter-EIGRP seq 10 deny 3.3.3.0/24 le 28
R3(config)#ip prefix-list Filter-EIGRP seq 20 permit 0.0.0.0/0 le 32

Masukkin Prefix-listnya ke EIGRP.

R3(config)#router eigrp 10
R3(config-router)#distribute-list prefix Filter-EIGRP out

Tunggu notif dan cek routing table.

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
D        2.2.2.2 [90/156160] via 11.11.11.2, 00:46:10, FastEthernet0/0
      3.0.0.0/8 is variably subnetted, 3 subnets, 3 masks
D        3.3.3.3/32 [90/158720] via 11.11.11.2, 00:45:28, FastEthernet0/0
D        3.3.3.4/30 [90/158720] via 11.11.11.2, 00:08:50, FastEthernet0/0
D        3.3.3.8/29 [90/158720] via 11.11.11.2, 00:09:14, FastEthernet0/0
      11.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        11.11.11.0/24 is directly connected, FastEthernet0/0
L        11.11.11.1/32 is directly connected, FastEthernet0/0
      22.0.0.0/24 is subnetted, 1 subnets
D        22.22.22.0 [90/30720] via 11.11.11.2, 00:46:16, FastEthernet0/0

Done.

Thanks.