Encore electronic ENMGS-16+2 - Manual (Page 45)

Tag VLAN Setting
The IEEE802.1Q protocol defines a new format of the frame; it adds a
tag header in the original Ethernet frame, as follows:
IEEE802.1Q Tag VLAN is divided by VLAN ID (VID). On receiving
a frame, the switch checks the VID in the tag header of the frame to
decide which VLAN it belongs to. If the receiving frame doesn’t
contain the tag header, the switch will assign a tag to the frame, using
the PVID of the port as its VID.
Figure 29. Tag VLAN
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