LAB 9. BGP Attribute ( Community LIST )

 LAB 9. BGP Attribute ( Community LIST )

Selain menggunakan teknik sebelumnya, kita juga bisa menggunakan numerik community, terlebih dahulu kita hapus konfig BGP dan EIGRP pada lab sebelumnya.

R1(config)#no router eigrp 10

R2(config)#no router eigrp 10

R1(config)#no router bgp 12

R2(config)#no router bgp 12

R3(config)#no router eigrp 10

R3(config)#no router bgp 3

R4(config)#no router bgp 4

Konfigurasikan BGP pada semua router.

R1:

R1(config)#router bgp 1

R1(config-router)#neighbor 12.12.12.2 remote-as 2

R1(config-router)#exit

R2:

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

R2(config-router)#neighbor 24.24.24.4 remote-as 4

R3:

R3(config)#router bgp 3

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

R4:

R4(config)#router bgp 4

R4(config-router)#neighbor 24.24.24.2 remote-as 2

R4(config-router)#network 4.4.4.4 mask 255.255.255.255

R4(config-router)#exit

Kita cek apakah R2 (ISP 2) mendapatkan prefix dari customer (R4).

R2:

R2(config)#do sh ip bgp

Network Next Hop Metric LocPrf Weight Path

*> 4.4.4.4/32 24.24.24.4 0 0 4 i

Ok sudah ada, sekarang kita lanjut konfigurasi communitynya.

R2:

R2(config)#ip community-list 1 permit 2:24

R2(config)#route-map P

R2(config)#route-map PREPEND permit

R2(config-route-map)#match community 1

R2(config-route-map)#set as prepend 2 2 2 2

R2(config-route-map)#exit

R2(config)#route-map PREPEND permit 20

Kemudian kita terapkan ke R3 (ISP3).

R2:

R2(config)#router bgp 2

R2(config-router)#neighbor 23.23.23.3 route-map PREPEND out

R2(config-router)#exit

Kemudian kita konfigurasi di bagian router customer

R4:

R4(config)#ip prefix-list Loopback permit 4.4.4.4/32

R4(config)#route-map PREPEND_COMMUNITY permit 10

R4(config-route-map)#match ip address prefix-list LOOPBACK

R4(config-route-map)#set community 2:24

R4(config-route-map)#exit

R4(config)#route-map PREPEND_COMMUNITY permit 20

R4(config-route-map)#exit

R4(config)#router bgp 4

R4(config-router)#neighbor 24.24.24.2 route-map PREPEND_COMMUNITY out

R4(config-router)#neighbor 24.24.24.2 send-community

R4(config-router)#exit

R4(config)#do clear ip bgp

Kita verifikasi pada R2.

R2:

R2(config)#do show ip bgp 4.4.4.4

BGP routing table entry for 4.4.4.4/32, version 7

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Flag: 0x820

Advertised to update-groups:

1 2

24.24.24.4 from 24.24.24.4 (4.4.4.4)

Origin IGP, metric 0, localpref 100, valid, external, best

Community: 131096

Untuk nilai communitynya masih menggunakan 32 bit dalam bentuk

decimal. Untuk merubah kedalam 16 bit, kita tulis command dibawah ini.

R2:

R2(config)#ip bgp-community new-format

Kita verifikasi kembali.

R2:

R2(config)#do sh ip bgp 4.4.4.4

BGP routing table entry for 4.4.4.4/32, version 7

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Advertised to update-groups:

1 2

4

24.24.24.4 from 24.24.24.4 (4.4.4.4)

Origin IGP, metric 0, localpref 100, valid, external, best

Community: 2:24

Kita cek pada R3, pastikan network 4.4.4.4 untuk AS-Prependnya sudah ditambahkan.

R3:

R3(config)#do sh ip bgp

BGP table version is 7, local router ID is 33.33.33.33

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 4.4.4.4/32 23.23.23.2 0 2 2 2 2 2 4 i