Prueba 3

Alestra
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/routing bgp instance
set default as=300 redistribute-connected=yes redistribute-static=yes
/ip address
add address=1.1.1.2/30 comment=to-Facebook interface=ether1 network=1.1.1.0
add address=2.2.2.2/24 comment=to-Google interface=ether2 network=2.2.2.0
add address=3.3.3.1/24 comment=to-ISP-Borde interface=ether3 network=3.3.3.0
add address=7.7.7.1/24 comment=to-ISP-Borde2 interface=ether4 network=7.7.7.0
/ip dhcp-client
add disabled=no interface=ether1
/routing bgp network
add network=3.3.3.0/24 synchronize=no
/routing bgp peer
add name=peer-to-facebook remote-address=1.1.1.1 remote-as=100
add name=peer-to-google remote-address=2.2.2.1 remote-as=200
add name=peer-to-isp-borde remote-address=3.3.3.2 remote-as=400
add name=peer-to-isp-core2 remote-address=7.7.7.2 remote-as=500
/system identity
set name=Alestra
/tool romon
set enabled=yes
Borde 2
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/routing bgp instance
set default as=500
/ip address
add address=7.7.7.2/24 interface=ether1 network=7.7.7.0
add address=5.5.5.254/24 interface=ether2 network=5.5.5.0
/ip dhcp-client
add disabled=no interface=ether1
/routing bgp network
add network=5.5.4.0/22 synchronize=no
/routing bgp peer
add name=peer1 remote-address=7.7.7.1 remote-as=300
/system identity
set name=Isp-Borde2
/tool romon
Core 2
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/ip address
add address=5.5.5.2/24 interface=ether1 network=5.5.5.0
add address=192.168.10.254/24 interface=ether2 network=192.168.10.0
/ip firewall nat
add action=masquerade chain=srcnat out-interface=ether1
/ip route
add distance=1 gateway=5.5.5.254
/system identity
set name=ISP-Core
/tool romon