Mikrotik: BGP Sederhana tanpa filter
Ada tiga (3) ISP
ISP1:
AS 10
ISP2
AS 20
ISP3 (kita)
AS 30 IP 10.1.1.0/24 IP 10.1.2.0/24
Setup connection
ISP1
/ip address
ISP2
/ip address
ISP3
/ip address
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.
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
Network Advertisements and Routing Filters
Now we can start to advertise our networks and filter out all other unnecessary advertisements.
First step is to advertise our networks
/routing bgp network add network=10.1.1.0/24 synchronize=no add network=10.1.2.0/24 synchronize=no
Next step is to specify which routing filter chains will be used
/routing bgp peer set isp1 in-filter=isp1-in out-filter=isp1-out set isp2 in-filter=isp2-in out-filter=isp2-out
in-filter is for incoming (received) prefixes, out-filter is for advertised prefixes.
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
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