Comnet CNGE2FE24MS, Installation And Operation Manual

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802.1Q VLAN
Virtual Local Area Network (VLAN) can be implemented on the switch to logically create
different broadcast domain.
When the 802.1Q VLAN function is enabled, all ports on the switch belong to default
VLAN of VID 1, which means they logically are regarded as members of the same
broadcast domain. The valid VLAN ID is in the range of number between 1 and 4094.
The amount of VLAN groups is up to 256 including default VLAN that cannot be deleted.
Each member port of 802.1Q is on either an Access Link (to be VLAN-tagged) or a Trunk
Link (will not be VLAN-tagged). All frames into an Access Link carry no VLAN
identification. Conversely, all frames into a Trunk Link are previously VLAN-tagged.
Besides, there is the third mode—Hybrid. A Hybrid Link can carry both VLAN-tagged
frames and untagged frames. A single port is supposed to belong to one VLAN group,
except when it is on a Trunk/Hybrid Link.
The technique of 802.1Q tagging inserts a 4-byte tag, including VLAN ID of the
destination port—PVID, in the frame. With the combination of Access/Trunk/Hybrid Links,
the communication across switches also can make the packet sent through tagged and
untagged ports.