Basic QinQ
Basic QinQ, also called QinQ tunneling, is performed based on interfaces. After basic QinQ is configured on an interface, packets received on the interface are tagged with the default VLAN ID of the interface. After being processed by basic QinQ on an interface, single-tagged packets change into double-tagged packets, and untagged packets change into single-tagged packets with the default VLAN tag of the interface.
Basic QinQ can be configured to expand VLAN space when multiple VLANs are required.
Configure PE1 to add the outer VLAN 10 to packets received on Port1 and Port2 and outer VLAN 20 to packets received on Port3.
Configure PE2 to add the outer VLAN 20 to packets received on Port1 and Port2.
Configure Port4 on PE1 and Port3 on PE2 to allow packets of VLAN 20 to pass.