VLAN frames
The frame decoder recognizes an outer VLAN-tagged frame if the TPID (tag protocol identifier) is 0x8100, 0x88A8 or equal to an alternative TPID determined by the AltTPID parameter in the ntservice.ini file (see ntservice.ini file in DN-0449).
A maximum of 3 VLANs are supported.
Note: VLAN tags are only recognized if they appear right after the layer 2 source MAC
address or a VN-Tag.
VLAN length
The length of the VLAN field depends on the number of VLANs. The possible values are 0, 4, 8 and 12 bytes.