Cisco: BGP Sederhana tanpa filter
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 Eth1/0 -> ISP3 Eth1/0 ISP1 Eth1/1 -> ISP2 Eth1/1 ISP2 Eth1/0 -> ISP3 Eth1/1 ISP1 Eth1/2 10.100.100.1/24 ISP1 Eth1/3 10.100.200.1/24 ISP2 Eth1/2 10.10.10.1/24 ISP2 Eth1/3 10.10.20.1/24 ISP3 Eth1/2 10.1.1.1/24 ISP3 Eth1/3 10.1.2.1/24
Setup connection
ISP1
enable
configure terminal
interface Ethernet1/0
ip address 192.168.1.1 255.255.255.0
no shutdown
exit
interface Ethernet1/1
ip address 192.168.3.1 255.255.255.0
no shutdown
exit
interface Ethernet1/2
ip address 10.100.100.1 255.255.255.0
no shutdown
exit
interface Ethernet1/3
ip address 10.100.200.1 255.255.255.0
no shutdown
exit
end
ISP2
enable
configure terminal
interface Ethernet1/0
ip address 192.168.2.1 255.255.255.0
no shutdown
exit
interface Ethernet1/1
ip address 192.168.3.2 255.255.255.0
no shutdown
exit
interface Ethernet1/2
ip address 10.10.10.1 255.255.255.0
no shutdown
exit
interface Ethernet1/3
ip address 10.10.20.1 255.255.255.0
no shutdown
exit
end
ISP3
enable
configure terminal
interface Ethernet1/0
ip address 192.168.1.2 255.255.255.0
no shutdown
exit
interface Ethernet1/1
ip address 192.168.2.2 255.255.255.0
no shutdown
exit
interface Ethernet1/2
ip address 10.1.1.1 255.255.255.0
no shutdown
exit
interface Ethernet1/3
ip address 10.1.2.1 255.255.255.0
no shutdown
exit
end
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:
enable
configure terminal
router bgp 10
bgp router-id 192.168.1.1
address-family ipv4 unicast
network 10.100.100.0
network 10.100.200.0
neighbor 192.168.3.2 remote-as 20
neighbor 192.168.1.2 remote-as 30
neighbor 192.168.3.2 activate
neighbor 192.168.1.2 activate
! neighbor 192.168.3.2 default-originate
! neighbor 192.168.1.2 default-originate
end
ISP2:
enable
configure terminal
router bgp 20
bgp router-id 192.168.2.1
address-family ipv4 unicast
network 10.10.10.0
network 10.10.20.0
neighbor 192.168.3.1 remote-as 10
neighbor 192.168.2.2 remote-as 30
neighbor 192.168.3.1 activate
neighbor 192.168.2.2 activate
end
ISP3:
enable
configure terminal
router bgp 30
bgp router-id 192.168.1.2
address-family ipv4 unicast
network 10.1.1.0
network 10.1.2.0
neighbor 192.168.1.1 remote-as 10
neighbor 192.168.2.1 remote-as 20
neighbor 192.168.1.1 activate
neighbor 192.168.2.1 activate
end
Network Advertisements and Routing Filters
Now we can start to advertise our networks and filter out all other unnecessary advertisements.
ISP1:
/routing bgp network add network=10.100.100.0/24 synchronize=no add network=10.100.200.0/24 synchronize=no
ISP2:
/routing bgp network add network=10.10.10.0/24 synchronize=no add network=10.10.20.0/24 synchronize=no
ISP3:
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
Cek routing
/ip route print
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.
Cek
show ip route show ip bgp neighbors 192.168.2.2 advertised-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