Optical Systems Design OSD2512 User Manual page 190

If the Custom S-port is configured to accept Untagged Only frames, custom S-tagged frames
will be discarded (except for priority custom S-tagged frames). C-tagged frames are initially
considered untagged and will therefore not be discarded. Later on in the ingress classification
process, they will get classified to the VLAN embedded in the tag instead of the port VLAN ID.
Ingress Filtering
Hybrid ports allow for changing ingress filtering. Access and Trunk ports always have ingress
filtering enabled.
If ingress filtering is enabled (checkbox is checked), frames classified to a VLAN that the port
is not a member of get discarded.
If ingress filtering is disabled, frames classified to a VLAN that the port is not a member of
are accepted and forwarded to the switch engine. However, the port will never transmit frames
classified to VLANs that it is not a member of.
Ingress Acceptance
Hybrid ports allow for changing the type of frames that are accepted on ingress.
Tagged and Untagged
Both tagged and untagged frames are accepted. See Port Type for a description of when a
frame is considered tagged.
Tagged Only
Only frames tagged with the corresponding Port Type tag are accepted on ingress.
Untagged Only
Only untagged frames are accepted on ingress. See Port Type for a description of when a
frame is considered untagged.
Egress Tagging
Ports in Trunk and Hybrid mode may control the tagging of frames on egress.
Untag Port VLAN
Frames classified to the Port VLAN are transmitted untagged. Other frames are transmitted
with the relevant tag.
Tag All
All frames, whether classified to the Port VLAN or not, are transmitted with a tag.
Untag All
All frames, whether classified to the Port VLAN or not, are transmitted without a tag.
This option is only available for ports in Hybrid mode.
Allowed VLANs
Ports in Trunk and Hybrid mode may control which VLANs they are allowed to become
members of. Access ports can only be member of one VLAN, the Access VLAN.
The field's syntax is identical to the syntax used in the Enabled VLANs field. By default, a
Trunk or Hybrid port will become member of all VLANs, and is therefore set to 1-4095.
The field may be left empty, which means that the port will not become member of any
VLANs.
Forbidden VLANs
A port may be configured to never become member of one or more VLANs. This is
particularly useful when dynamic VLAN protocols like MVRP and GVRP must be prevented
from dynamically adding ports to VLANs.
The trick is to mark such VLANs as forbidden on the port in question. The syntax is identical
to the syntax used in the Enabled VLANs field.
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OPTICAL SYSTEMS DESIGN
OSD2512 OPERATOR MANUAL
DOC ID: 10118101