
136 Chapter 5 Creating and managing VLANs
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Accepting tagged and untagged frames
In the Business Policy Switch, you configure whether or not tagged frames are
sent or received on the port level. Refer to “VLAN tab for a single port” on
page 89 for VLAN tab field descriptions. Tagging is set as true or false for the port
and applied to all VLANs on that port. You can select whether or not to discard:
• Tagged frames received on a port where tagging is disabled
• Untagged frames received on a port where tagging is enabled
The default is not to discard the frames. You can also designate the port-based
VLAN to which these frames are assigned by setting the tagged port’s default
VID (the default is 1).
A Business Policy Switch switch port with tagging enabled is a port from which
all frames sent are tagged. A tagged port can be configured to discard untagged
frames or to associate them with a VLAN set by the PVID. In the latter case, when
an untagged frame is received on a tagged port, it is sent to the user-specified
PVID.
A port with tagging disabled is a port that does not send tagged frames. If a tagged
frame is forwarded out a port with tagging set to false, the switch removes the tag
from the frame before sending it out the port. When a port with tagging set to false
receives a frame, it can be configured to discard tagged frames or to associate
them with the VLAN specified in the tag.
To set a port to discard tagged frames it receives:
1 In the Device Manager main window, select a port.
2 From the Device Manager menu bar, choose Edit > Port.
The Port dialog box opens displaying the Interface tab.
Note: To optimize performance, on untagged ports in configurations
where you do not expect to see tagged frames, set DiscardTaggedFrames
to true. However, on untagged ports for interconnecting switches, it is
probably better to set DiscardTaggedFrames to false. Then, if you
convert an interswitch port from an untagged port to a tagged port,
connectivity is not lost.
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