Q-in-Q MikroTik

Original 802.1Q allows only one vlan header, Q-in-Q on the other hand allows two or more vlan headers. In RouterOS Q-in-Q can be configured by adding one vlan interface over another. Example:

/interface vlan
add name=vlan1 vlan-id=11 interface=ether1
add name=vlan2 vlan-id=12 interface=vlan1

If any packet is sent over ‘vlan2′ interface, two vlan tags will be added to ethernet header – ’11’ and ’12’.