LAB 8. BGP Attribute (Community)
BGP Community digunakan untuk menambah info-info tambahan pada setiap prefix yang diadvertise ke router naighbor yang menjalankan BGP. Ada 4 community default yang bisa kita gunakan atau bisa juga menggunakan nilai numerik.
Di topologi sebelumnya, kita cabut kabel antara R3 dan R4 lalu sambung kabel antara R3 dan R4, kemudian sambung kabel dari R2 ke R4 sesuai topologi, kemudian hapus config bekas lab sebelumnya.
R1,R2,R3
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 config Ip address di R2,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
Config 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(config)#do 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
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
Sekarang Kita cek Hasil BGO R3,R4 bandingkan hasilnya pastikan network 11.11.11.11.11/32 sudah gak 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, pastikan network 33.33.33.33/32 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
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