Mikrotik: BGP Dua Link main backup - dengan as-path PREPEND
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Ada tiga (3) ISP
ISP1:
IP 192.168.1.1/24 menuju ISP3 IP 192.168.3.1/24 menuju ISP2 AS 10 IP 10.100.100.0/24 IP 10.100.200.0/24
ISP2
IP 192.168.2.1/24 - menuju ISP3 IP 192.168.3.2/24 - menuju ISP1 AS 20 IP 10.10.10.0/24 IP 10.10.20.0/24
ISP3 (kita)
IP 192.168.1.2/24 - menuju ISP1 IP 192.168.2.2/24 - menuju ISP2 AS 30 IP 10.1.1.0/24 IP 10.1.2.0/24
Sambungan Fisik
ISP1 e0 -> ISP3 e0 ISP1 e1 -> ISP2 e1 ISP2 e0 -> ISP3 e1 ISP1 e2 10.100.100.1/24 ISP1 e3 10.100.200.1/24 ISP2 e2 10.10.10.1/24 ISP2 e3 10.10.20.1/24 ISP3 e2 10.1.1.1/24 ISP3 e3 10.1.2.1/24
Setup connection
ISP1
/ip address add address=192.168.1.1/24 interface=ether1 /ip address add address=192.168.3.1/24 interface=ether2 /ip address add address=10.100.100.1/24 interface=ether3 /ip address add address=10.100.200.1/24 interface=ether4
ISP2
/ip address add address=192.168.2.1/24 interface=ether1 /ip address add address=192.168.3.2/24 interface=ether2 /ip address add address=10.10.10.1/24 interface=ether3 /ip address add address=10.10.20.1/24 interface=ether4
ISP3
/ip address add address=192.168.1.2/24 interface=ether1 /ip address add address=192.168.2.2/24 interface=ether2 /ip address add address=10.1.1.1/24 interface=ether3 /ip address add address=10.1.2.1/24 interface=ether4
BGP Peering
Consider that IP connectivity between ISPs edge routers and Our Core router is already set up and working properly. So we can start to establish BGP peering to both ISPs.
ISP1:
#set our AS number /routing bgp instance set default as=10 #add BGP peers /routing bgp peer add name=toISP2 remote-address=192.168.3.2 remote-as=20 add name=toISP3 remote-address=192.168.1.2 remote-as=30 # jika ingin redistribute default route ke client yang spesifik # add name=toISP2 remote-address=192.168.3.2 remote-as=20 default-originate=if-installed # add name=toISP3 remote-address=192.168.1.2 remote-as=30 default-originate=if-installed # # advertize routing # /routing bgp network add network=10.100.100.0/24 synchronize=no add network=10.100.200.0/24 synchronize=no
ISP2:
#set our AS number /routing bgp instance set default as=20 #add BGP peers /routing bgp peer add name=toISP1 remote-address=192.168.3.1 remote-as=10 add name=toISP3 remote-address=192.168.2.2 remote-as=30 # # advertize routing # /routing bgp network add network=10.10.10.0/24 synchronize=no add network=10.10.20.0/24 synchronize=no
ISP3:
#set our AS number /routing bgp instance set default as=30 #add BGP peers /routing bgp peer add name=toISP1 remote-address=192.168.1.1 remote-as=10 add name=toISP2 remote-address=192.168.2.1 remote-as=20 # # advertize routing # /routing bgp network add network=10.1.1.0/24 synchronize=no add network=10.1.2.0/24 synchronize=no
Main/Backup link setup
ISP3
Lakukan
- accept network kita sendiri
- drop semua tabel IP lainnya, karena kita tidak mau menjadi transit provider
- BGP AS prepend - menaikan AS path
# setup routing filter # /routing bgp peer set toISP1 in-filter=isp1-in out-filter=isp1-out set toISP2 in-filter=isp2-in out-filter=isp2-out # # Outgoing filter ke ISP1: # /routing filter #accept our networks add chain=isp1-out prefix=10.1.1.0/24 action=accept add chain=isp1-out prefix=10.1.2.0/24 action=accept #discard the rest add chain=isp1-out action=discard # # Outgoing filter ke ISP2: # /routing filter #accept our networks and prepend AS path three times add chain=isp2-out prefix=10.1.1.0/24 action=accept set-bgp-prepend=3 add chain=isp2-out prefix=10.1.2.0/24 action=accept set-bgp-prepend=3 #discard the rest add chain=isp2-out action=discard # # ISP1 menjadi main # ISP2 menjadi backup # /routing filter add chain=isp1-in action=discard add chain=isp2-in action=discard # /ip route add gateway=192.168.1.1 check-gateway=ping add gateway=192.168.2.1 distance=30 check-gateway=ping
Load sharing setup
Teknik melakukan multihoming / download sharing
ISP3
Disini salah satu network kita di prepend yang berbeda antara ISP1 dan ISP2
# Outgoing filter ke ISP1: # /routing filter #accept our networks and prepend second network add chain=isp1-out prefix=10.1.1.0/24 action=accept add chain=isp1-out prefix=10.1.2.0/24 action=accept set-bgp-prepend=3 #discard the rest add chain=isp1-out action=discard # # Outgoing filter ke ISP2: # /routing filter #accept our networks and prepend first network add chain=isp2-out prefix=10.1.1.0/24 action=accept set-bgp-prepend=3 add chain=isp2-out prefix=10.1.2.0/24 action=accept #discard the rest add chain=isp2-out action=discard
Konfigurasi di atas hanya untuk outgoing packet dari network kita. Ada beberapa pilihan,
- biarkan gateway menggunakan konfigurasi main/backup - ini akan menyebabkan hanya satu link yang digunakan dan routing akan asymetric.
- gunakan policy routing untuk memaksa outgoing packet menggunakan link yang sama dengan dengan incoming
- Menggnakan BGP untuk menerima full routing table dari ke dua peer dan menggunakan BGP attribute untuk melakukan routing melalui satu sambungan / link dan sebagian lagi melalui link lainnya. Contoh, traffic local / nasional bisa dikirim menggunakan ISP1 dan Internasional menggunakan ISP2.
Referensi