Compatibility of EtherTypes in QinQ Tags
As shown in Figure 1, an IEEE 802.1Q tag lies between the Source Address field and the Length/Type field. The default EtherType value in the 2–byte Tag Protocol Identifier (TPID) is 0x8100. If the EtherType value of a packet is 0x8100, the packet is tagged. The EtherType value in a QinQ packet varies with the settings of device manufactures. Huawei devices use the default value 0x8100 while some non-Huawei devices use 0x9100 as the EtherType value. To implement interworking between Huawei devices and non-Huawei devices, you need to configure compatibility of EtherTypes in inner and outer tags of QinQ packets sent by the devices of different vendors.
In Figure 2, Device A is a non-Huawei device that uses 0x9100 as the EtherType value, and Device B is a Huawei device which uses 0x8000 as the EtherType value. To implement interworking between the Huawei and the non-Huawei devices, configure 0x9100 as the EtherType value in the outer VLAN tag of QinQ packets sent by the Huawei device.
