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•
Accepts untagged and C-tagged frames
•
Discards all frames not classified to the Access VLAN
•
On egress all frames are transmitted untagged
Trunk:
Trunk ports can carry traffic on multiple VLANs simultaneously, and are normally used to connect to other
switches. Trunk ports have the following characteristics:
•
By default, a trunk port is member of all VLANs (1-4095)
•
The VLANs that a trunk port is member of may be limited by the use of Allowed VLANs
•
Frames classified to a VLAN that the port is not a member of are discarded
•
By default, all frames but frames classified to the Port VLAN (a.k.a. Native VLAN) get tagged on egress.
Frames classified to the Port VLAN do not get C-tagged on egress
•
Egress tagging can be changed to tag all frames, in which case only tagged frames are accepted on
ingress
Hybrid:
Hybrid ports resemble trunk ports in many ways, but adds additional port configuration features. In addition to
the characteristics described for trunk ports, hybrid ports have these abilities:
•
Can be configured to be VLAN tag unaware, C-tag aware, S-tag aware, or S-custom-tag aware
•
Ingress filtering can be controlled
•
Ingress acceptance of frames and configuration of egress tagging can be configured independently
Port VLAN
Determines the port's VLAN ID (a.k.a. PVID). Allowed VLANs are in the range 1 through 4095, default being 1.
On ingress, frames get classified to the Port VLAN if the port is configured as VLAN unaware, the frame is
untagged, or VLAN awareness is enabled on the port, but the frame is priority tagged (VLAN ID = 0).
On egress, frames classified to the Port VLAN do not get tagged if Egress Tagging configuration is set to untag
Port VLAN. The Port VLAN is called an "Access VLAN" for ports in Access mode and Native VLAN for ports in
Trunk or Hybrid mode.
Port Type
Ports in hybrid mode allow for changing the port type, that is, whether a frame's VLAN tag is used to classify the
frame on ingress to a particular VLAN, and if so, which TPID it reacts on. Likewise, on egress, the Port Type
determines the TPID of the tag, if a tag is required.
Unaware:
On ingress, all frames, whether carrying a VLAN tag or not, get classified to the Port VLAN, and possible tags are
not removed on egress.
C-Port:
On ingress, frames with a VLAN tag with TPID = 0x8100 get classified to the VLAN ID embedded in the tag.
If a frame is untagged or priority tagged, the frame gets classified to the Port VLAN.
If frames must be tagged on egress, they will be tagged with a C-tag.
S-Port:
On egress, if frames must be tagged, they will be tagged with an S-tag.
On ingress, frames with a VLAN tag with TPID = 0x88A8 get classified to the VLAN ID embedded in the tag.
Priority-tagged frames are classified to the Port VLAN.
If the port is configured to accept
Tagged Only
frames (see Ingress Acceptance below), frames without this TPID
are dropped.
