zyVlanStackTunnelPortTpid

TPID is a standard Ethernet type code identifying the frame and indicates whether the frame carries IEEE 802.1Q tag information. 
Set a four-digit hexadecimal number from 0000 to FFFF that the switch adds in the outer VLAN tag of the frames sent on the tunnel port(s). 
The switch also uses this to check if the received frames are double-tagged. The value of this field is 0x8100 as defined in IEEE 802.1Q.
If the switch needs to communicate with other vendors' devices, they should use the same TPID.

MIB

ZYXEL-VLAN-STACK-MIB

OID

.1.3.6.1.4.1.890.1.15.3.89.1.2.1.4

Type

column

Access

readwrite

Status

current

Parent

zyxelVlanStackPortEntry