/ip firewall nat
add action=dst-nat chain=dstnat protocol=tcp in-interface=ether1 to-addresses=192.168.7.1
add action=dst-nat chain=dstnat protocol=tcp in-interface=ether2 to-addresses=192.168.7.1
add action=dst-nat chain=dstnat protocol=tcp in-interface=ether3 to-addresses=192.168.7.1
add action=masquerade chain=srcnat src-address=192.168.7.1 out-interface=ether1
add action=masquerade chain=srcnat src-address=192.168.7.1 out-interface=ether2
add action=masquerade chain=srcnat src-address=192.168.7.1 out-interface=ether3
add action=masquerade chain=srcnat dst-address=192.168.7.1 in-interface=ether1
add action=masquerade chain=srcnat dst-address=192.168.7.1 in-interface=ether2
add action=masquerade chain=srcnat dst-address=192.168.7.1 in-interface=ether3
/ip firewall nat
add action=masquerade chain=srcnat src-address=192.168.7.1 out-interface=ether1
add action=masquerade chain=srcnat src-address=192.168.7.1 out-interface=ether2
add action=masquerade chain=srcnat src-address=192.168.7.1 out-interface=ether3
add action=masquerade chain=srcnat dst-address=192.168.7.1 in-interface=ether1
add action=masquerade chain=srcnat dst-address=192.168.7.1 in-interface=ether2
add action=masquerade chain=srcnat dst-address=192.168.7.1 in-interface=ether3
/ip firewall nat
add action=dst-nat chain=dstnat protocol=tcp in-interface=ether1 to-addresses=192.168.7.1
add action=dst-nat chain=dstnat protocol=tcp in-interface=ether2 to-addresses=192.168.7.1
add action=dst-nat chain=dstnat protocol=tcp in-interface=ether3 to-addresses=192.168.7.1
или
/ip firewall nat add action=dst-nat chain=dstnat protocol=tcp in-interface=ether1, ether2,ether3 to-addresses=192.168.7.1
Филиал_1
/interface vlan
add interface={ИНТЕРФЕЙС ПРОВАЙДЕРА} name=vlan500 vlan-id=500
/ip address
add address=100.100.105.2/24 comment=Office_main interface=vlan500 network=100.100.105.0
Филиал_2
/interface vlan
add interface={ИНТЕРФЕЙС ПРОВАЙДЕРА} name=vlan600 vlan-id=600
/ip address
add address=100.100.106.2/24 comment=Office_main interface=vlan500 network=100.100.106.0
Главный офис
/interface vlan
add interface={ИНТЕРФЕЙС ПРОВАЙДЕРА} name=vlan500 vlan-id=500
add interface={ИНТЕРФЕЙС ПРОВАЙДЕРА} name=vlan600 vlan-id=500
/ip address
add address=100.100.105.1/24 comment=Branch1 interface=vlan500 network=100.100.105.0
add address=100.100.106.1/24 comment=Branch1 interface=vlan600 network=100.100.106.0
Пинг ходить не должен.