This MIB defines configuration and monitoring capabilities relating to 802.1QinQ interfaces. QinQ interfaces are capable of terminating QinQ traffic and translating QinQ tags. IEEE 802.1Q VLAN specification provides for an option to tag Ethernet frames with two VLAN tags: - An inner tag that specifies the customer's VLAN ID. This tag is called the 'CE VLAN'. - An outer tag that specifies the service provider's VLAN ID. This tag is called the 'metro tag', or the 'PE VLAN'. The combination of inner and outer VLAN tags is used to uniquely identify a particular customer's service flow.