Mikrotik: BGP Dua Link main backup
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
ISP1 ether0 -> ISP3 ether0 ISP1 ether1 -> ISP2 ether1 ISP2 ether0 -> ISP3 ether1 ISP1 ether2 10.100.100.1/24 ISP1 ether3 10.100.200.1/24 ISP2 ether2 10.10.10.1/24 ISP2 ether3 10.10.20.1/24 ISP3 ether2 10.1.1.1/24 ISP3 ether3 10.1.2.1/24
Setup connection
ISP1
/ip address add interface=ether1 address=192.168.1.1/24 /ip address add interface=ether2 address=192.168.3.1/24 /ip address add interface=ether3 address=10.100.100.1/24 /ip address add interface=ether3 address=10.100.200.1/24
ISP2
/ip address add interface=ether1 address=192.168.2.1/24 /ip address add interface=ether2 address=192.168.3.2/24 /ip address add interface=ether3 address=10.10.10.1/24 /ip address add interface=ether4 address=10.10.20.1/24
ISP3
/ip address add interface=ether1 address=192.168.1.2/24 /ip address add interface=ether2 address=192.168.2.2/24 /ip address add interface=ether3 address=10.1.1.1/24 /ip address add interface=ether4 address=10.1.2.1/24
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=toISP3 remote-address=192.168.1.2 remote-as=30 add name=toISP2 remote-address=192.168.3.2 remote-as=20
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
Main / Backup Link Setup di ISP3
ISP3:
Lakukan
- accept network kita sendiri
- drop semua tabel IP lainnya, karena kita tidak mau menjadi transit provider
- BGP AS prepend - menaikan AS path
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
Cek
! perhatikan AS 30 di tambahkan 5x ke routing ke arah AS 10 ! show ip bgp
show ip route show ip bgp 10.100.1000.0/24 show ip bgp neighbors 192.168.2.2 advertised-routes show ip bgp neighbor 192.168.1.1 routes show bgp ipv4 unicast neighbors show bgp ipv4 unicast summary
Referensi
- https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/xe-16/irg-xe-16-book/configuring-a-basic-bgp-network.html
- https://wiki.mikrotik.com/wiki/Manual:Simple_BGP_Multihoming