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About 802.1Q tagged ports

Tagging a frame adds four octets to a frame, making it bigger than the traditional maximum frame size. These frames are sometimes referred to as "baby giant" frames. If a device does not support IEEE 802.1Q tagging, it may have problems interpreting tagged frames and receiving baby giant frames.

In the 8000 Series switch, whether or not tagged frames are sent or received depends on what you configure at the port level. Tagging is set as true or false for the port and is applied to all VLANs on that port.


Note: When you enable tagging on an untagged port, the port's previous configuration of VLANs, STGs, and MLTs is lost. In addition, the port resets and runs Spanning Tree Protocol, thus breaking connectivity while the protocol goes through the normal blocking and learning states before the forwarding state.

An 8000 Series switch port with tagging enabled sends frames explicitly tagged with a VLAN ID. Tagged ports are typically used to multiplex traffic belonging to multiple VLANs to other IEEE-802.1Q-compliant devices.

If tagging is disabled on an 8000 Series switch port, it does not send tagged frames. A nontagged port connects 8000 Series switches to devices that do not support IEEE 802.1Q tagging. If a tagged frame is forwarded out a port with tagging set to false, the Passport 8000 Series switch removes the tag from the frame before sending it out the port.

See also:


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