i3 International S81 User Manual page 102

Port VLAN
Port Type
Ingress Filtering
Access: Access ports are normally used to connect to end stations. Dynamic features like
Voice VLAN may add the port to more VLANs behind the scenes. Access ports have the
following characteristics:

Member of exactly one VLAN, the Port VLAN (Access VLAN) which by default is 1.

Accepts untagged frames and C-tagged frames.

Discards all frames that are 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 a member of all existing VLANs. This may be limited by the
use of Allowed VLANs

Unless VLAN Trunking is enabled on the port frames classified to a VLAN that the
port is not a member of will be 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

VLAN trunking may be enabled.
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 the VLAN tag unaware, C-tag aware, S-tag aware, or S-custom-
tag aware.

Ingress filtering can be controlled.

Ingress acceptance of frames and configureation of egress tagging can be configured
independently.
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 un-tag 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.
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.
G-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 ingress, frames with a VLAN tag with TPID = 0x8100 or 0x88A8 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 an S-tag.
S-Custom-Port: On ingress, frames with a VLAN tag with a TPID = 0x8100 or equal to the
Ethertype configured for Custom-S ports 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 the custom S-tag.
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 to which it is
not a member.
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