Configuring the TPID value in VLAN tags

TPID (tag protocol identifier) identifies a frame as an 802.1Q tagged frame. On the device, the TPID in the 802.1Q tag added on a basic QinQ-enabled port is by default 0x8100, in compliant with IEEE 802.1Q. However, the TPID value varies with vendors. In a multi-vendor network, you must make sure the TPID setting is the same across all devices so 802.1Q tagged frames can be correctly handled.

TPID settings include CVLAN TPID and SVLAN TPID.

A basic QinQ or customer-side QinQ enabled port uses the CLAN TPID to match incoming tagged frames. An incoming frame is handled as an untagged frame if its TPID is different from the CVLAN TPID. The device supports one CVLAN TPID for all QinQ-enabled ports.

A service provider-side port uses the SVLAN TPID to replace the TPID in outgoing frames' SVLAN tags, in addition to matching incoming tagged frames. SVLAN TPIDs are configurable on a per-port basis.

For example, the PE device is connected to a customer device that uses the TPID 0x8200 and to a provider device that uses the TPID 0x9100. To be compatible with these devices, you must configure 0x8200 and 0x9100 as the CVLAN TPID and SVLAN TPID, respectively. Otherwise, the devices cannot correctly identify tagged frames between them.