=== R1 ===
hostname R1
ip cef
interface Loopback0
 ip address 10.255.0.1 255.255.255.255
exit
interface GigabitEthernet1
 ip address 192.0.2.1 255.255.255.248
 no shutdown
exit
router ospf 1
 router-id 10.255.0.1
 network 10.255.0.1 0.0.0.0 area 0
 network 192.0.2.1 0.0.0.0 area 0
 passive-interface Loopback0
exit
router bgp 65123
 bgp router-id 10.255.0.1
 no bgp default ipv4-unicast
 neighbor 10.255.0.2 remote-as 65123
 neighbor 10.255.0.2 update-source Loopback0
 neighbor 10.255.0.3 remote-as 65123
 neighbor 10.255.0.3 update-source Loopback0
 address-family ipv4 unicast
  neighbor 10.255.0.2 activate
  neighbor 10.255.0.3 activate
 exit-address-family
end

=== R2 ===
hostname R2
ip cef
interface Loopback0
 ip address 10.255.0.2 255.255.255.255
exit
interface GigabitEthernet1
 ip address 192.0.2.2 255.255.255.248
 no shutdown
exit
interface GigabitEthernet2
 ip address 192.0.2.9 255.255.255.252
 no shutdown
exit
router ospf 1
 router-id 10.255.0.2
 network 10.255.0.2 0.0.0.0 area 0
 network 192.0.2.2 0.0.0.0 area 0
 passive-interface Loopback0
exit
router bgp 65123
 bgp router-id 10.255.0.2
 no bgp default ipv4-unicast
 neighbor 10.255.0.1 remote-as 65123
 neighbor 10.255.0.1 update-source Loopback0
 neighbor 10.255.0.3 remote-as 65123
 neighbor 10.255.0.3 update-source Loopback0
 address-family ipv4 unicast
  neighbor 10.255.0.1 activate
  neighbor 10.255.0.3 activate
  network 192.0.2.8 mask 255.255.255.252
 exit-address-family
end

=== R3 ===
hostname R3
ip cef
interface Loopback0
 ip address 10.255.0.3 255.255.255.255
exit
interface GigabitEthernet1
 ip address 192.0.2.3 255.255.255.248
 no shutdown
exit
interface GigabitEthernet2
 ip address 192.0.2.10 255.255.255.252
 no shutdown
exit
router ospf 1
 router-id 10.255.0.3
 network 10.255.0.3 0.0.0.0 area 0
 network 192.0.2.3 0.0.0.0 area 0
 passive-interface Loopback0
exit
router bgp 65123
 bgp router-id 10.255.0.3
 no bgp default ipv4-unicast
 neighbor 10.255.0.1 remote-as 65123
 neighbor 10.255.0.1 update-source Loopback0
 neighbor 10.255.0.2 remote-as 65123
 neighbor 10.255.0.2 update-source Loopback0
 address-family ipv4 unicast
  neighbor 10.255.0.1 activate
  neighbor 10.255.0.2 activate
  network 192.0.2.8 mask 255.255.255.252
 exit-address-family
end