Layer 2 Selective QinQ

Layer 2 selective QinQ is an extension of QinQ tunneling but is more flexible. The major difference is as follows:

• QinQ tunneling adds the same outer tag to the frames that enter a QinQ interface.

• Layer 2 selective QinQ adds distinctive outer tags to the frames that enter a QinQ interface according to inner tags.

On the network shown in Figure 1, Company 1 and Company 2 have more than one branch.

• VLAN 2 to VLAN 500 are used on the networks of Company 1.

• VLAN 501 to VLAN 4094 are used on the networks of Company 2.

• Interface 1 on PE1 both receives packets from VLANs of Company 1 and Company 2.

Figure 1 Layer 2 selective QinQ

To allow branches to communicate within Company 1 or Company 2 but not between the two companies, configure Layer 2 selective QinQ on PE1 and PE2.

• Table 1 shows the planning of outer VLAN tags in the packets entering different interfaces on PE1 and PE2.

  Table 1 Outer VLAN tag planning on PE1 and PE2

  Device Name	Interface Name	VLAN ID Range	Outer VLAN ID
  PE1	Interface 1	2 to 500	10
  	Interface 1	1000 to 2000	20
  	Interface 2	100 to 500	10
  PE2	Interface 1	1000 to 4094	20
  	Interface 2	501 to 2500	20

• Interface 3 on PE1 or PE2 allows the packets tagged with VLAN 20 to pass.