LAB 8. BGP Attribute (Community)

LAB 8. BGP Attribute (Community) 

BGP Community digunakan untuk menambahka informasi tambahan pada setiap prefix yang diadvertise ke router tetangga yang menjalankan BGP. Ada 4 community default yang bisa kita gunakan atau bisa juga menggunakan nilai numerik.

Kesimpulannya :

•     Internet : advertise prefix kemanapun gak ada

•     No-advertise : jangan advertise network kemanapun

•     No-export : jangan advertise network ke e BGP manapun

•     Local AS : jangan advertise network ke luar SUB-AS ( Berlaku untuk BGP Confederation )

Untuk topologi sebelumnya, cabut kabel antara R3dan R4 lalu colok kabel antara R3 dan R4, kemudian colok kabel dari R2 ke R4 sesuai topologi, kemudian hapus config bekas lab sebelumnya.

R1(config)#no router bgp 1234

R2(config)#no router bgp 1234

R3(config)#no router bgp 1234

R3:

R3(config)#default int f0/1

R4:

R4(config)#default int f0/0

R4(config)#default int lo44

R4(config)#no int lo0

R4(config)#no router bgp 4

R4(config)#no router eigrp 10

Kita konfigurasikan IP Address pada R2 dan R4

R2:

R2(config)#int g1/0

R2(config-if)#ip add 24.24.24.2 255.255.255.0

R2(config-if)#no shutdown

R2(config)#int lo22

R2(config-if)#ip add 22.22.22.22 255.255.255.255

R4:

R4(config)#int g1/0

R4(config-if)#ip add 24.24.24.4 255.255.255.0

R4(config-if)#no shutdown

R4(config-if)#exit

R4(config)#int lo0

R4(config-if)#ip add 4.4.4.4 255.255.255.255

Kita konfigurasi BGP pada semua router. Disini R2 berperan sebagai route reflector server.

R1:

R1(config)#router bgp 123

R1(config-router)#network 11.11.11.11 mask 255.255.255.255

R1(config-router)#neighbor 2.2.2.2 remote-as 123

R1(config-router)#neighbor 2.2.2.2 update-source Loopback0

R2:

R2(config)#router bgp 123

R2(config-router)#neighbor 1.1.1.1 remote-as 123

R2(config-router)#neighbor 1.1.1.1 up lo0

R2(config-router)#neighbor 1.1.1.1 route-reflector-client

R2(config-router)#neighbor 1.1.1.1 next-hop-self

R2(config-router)#neighbor 3.3.3.3 remote-as 123

R2(config-router)#neighbor 3.3.3.3 update lo0

R2(config-router)#neighbor 3.3.3.3 route-reflector-client

R2(config-router)#neighbor 3.3.3.3 next-hop-self

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

R2(config-router)#network 22.22.22.22 mask 255.255.255.255

R3:

R3(config)#int lo33

R3(config-if)#ip add 33.33.33.33 255.255.255.255

R3(config)#router bgp 123

R3(config-router)#neighbor 2.2.2.2 remote-as 123

R3(config-router)#neighbor 2.2.2.2 up lo0

R3(config-router)#network 33.33.33.33 mask 255.255.255.255

R4:

R4(config)#router bgp 4

R4(config-router)#neighbor 24.24.24.2 remote-as 123

R4(config-router)#network 4.4.4.4 mask 255.255.255.255

R4(config-router)#exit

Kita cek bgp route di R1 dan R4.

R1:

R1#sh ip bgp

BGP table version is 6, local router ID is 11.11.11.11

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

*>i4.4.4.4/32 2.2.2.2 0 100 0 4 i

*> 11.11.11.11/32 0.0.0.0 0 32768 i

*>i22.22.22.22/32 2.2.2.2 0 100 0 i

*>i33.33.33.33/32 3.3.3.3 0 100 0 i

R4:

R4#show ip bgp

BGP table version is 5, local router ID is 4.4.4.4

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 0.0.0.0 0 32768 i

*> 11.11.11.11/32 24.24.24.2 0 123 i

*> 22.22.22.22/32 24.24.24.2 0 0 123 i

*> 33.33.33.33/32 24.24.24.2 0 123 i

Selanjutnya, kita set community ‘no-export’ di R1 (no Export tidak diadvertise ke e BGP).

R1:

R1(config)#access-list 1 permit host 11.11.11.11

R1(config)#route-map NO-EXPORT

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

R1(config-route-map)#set community no-export

R1(config-route-map)#router bgp 123

R1(config-router)#neighbor 2.2.2.2 route-map NO-EXPORT out

R1(config-router)#neighbor 2.2.2.2 send-community

Marilah kita cek bgp route R3 dan R4, kemudian kita bandingkan hasilnya. Pastikan network 11.11.11.11/32 sudah tidak ada.

R3:

R3(config)#do sh ip bgp

BGP table version is 5, 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

*>i4.4.4.4/32 2.2.2.2 0 100 0 4 i

*>i11.11.11.11/32 1.1.1.1 0 100 0 i

*>i22.22.22.22/32 2.2.2.2 0 100 0 i

*> 33.33.33.33/32 0.0.0.0 0 32768 i

R4:

R4(config)#do show ip bgp

BGP table version is 6, local router ID is 4.4.4.4

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 0.0.0.0 0 32768 i

*> 22.22.22.22/32 24.24.24.2 0 0 123 i

*> 33.33.33.33/32 24.24.24.2 0 123 i

Kita cek apakah pada prefix terdapat informasi tambahan yaitu no-export.

R2:

R2(config)#do show ip bgp 11.11.11.11

BGP routing table entry for 11.11.11.11/32, version 6

Paths: (1 available, best #1, table Default-IP-Routing-Table, not advertised to EBGP peer)

Flag: 0x880

Advertised to update-groups:

1

Local, (Received from a RR-client)

1.1.1.1 (metric 156160) from 1.1.1.1 (11.11.11.11)

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

Community: no-export

Sekarang, kita gentian ke community “no-advertise” di R3 (no-export tidak diadvertise ke i-BGP/e-BGP).

R3:

R3(config)#access-list 1 permit host 33.33.33.33

R3(config)#route-map NO-ADVERTISE

R3(config-route-map)#match ip address 1

R3(config-route-map)#set community no-advertise

R3(config-route-map)#router bgp 123

R3(config-router)#neighbor 2.2.2.2 route-map NO-ADVERTISE out

R3(config-router)#neighbor 2.2.2.2 send-community

R3(config-router)#exit

Kita cek BGP route di R1 dan R4, lalu kita pastikan bahwa network 33.33.33.33/32 sudah tidak ada.

R1:

R1(config)#do show ip bgp

Network Next Hop Metric LocPrf Weight Path

*>i4.4.4.4/32 2.2.2.2 0 100 0 4 i

*> 11.11.11.11/32 0.0.0.0 0 32768 i

*>i22.22.22.22/32 2.2.2.2 0 100 0 i

R4:

R4(config)#do show ip bgp

Network Next Hop Metric LocPrf Weight Path

*> 4.4.4.4/32 0.0.0.0 0 32768 i

*> 22.22.22.22/32 24.24.24.2 0 0 123 i

R2:

R2(config)#do show ip bgp 33.33.33.33

BGP routing table entry for 33.33.33.33/32, version 7

Paths: (1 available, best #1, table Default-IP-Routing-Table, not advertised to any peer)

Flag: 0x880

Not advertised to any peer

Local, (Received from a RR-client)

3.3.3.3 (metric 156160) from 3.3.3.3 (33.33.33.33)

Origin IGP, metric 0, localpref 100, valid, internal, best Community: no-advertise