Reference Guide

338 VLANs
• Trunk Ports
P
orts set to Trunk mode may belong to multiple VLANs. The
default
VLAN membe
rship of a trunk port is all VLANs (1-409
4). A PVID must be
set on the
port (it can be a non-existing VLAN). Trunk ports accept
tagged
a
nd untagged frames. Untagged frames will be classified to the
VLAN
w
hose VLAN ID (VID) is configured as the port’s PVID.
Frames, sent from the port in the VLAN, whose VID is the current PVID,
are sent untagged. Frames sent in all other VLANs active on the port are
sent tagged.
Ingress filtering is always enabled on Trunk-mode ports. Incoming f
rames
will under
go ingress filtering, and if correctly tagged, (tagged with a VID of
one of the VLANs to which the port currently belongs) are admi
tted.
The defaul
t PVID is 1 (the default VLAN). If another VID is configur
ed as
the
port’s PVID, and the corresponding VLAN is deleted from the po
rt or
from the
system, the port’s PVID reverts to 1, meaning that the port
is
made a membe
r of the default VLAN.
Setting a trunk-port’s PVID to 4095 limits traffic to tagged
frames.
Incoming unta
gged frames are silently discarded, and no frames are se
nt
untagged.
T
runk-mode ports are intended for switch-to-switch links, where traffic
is
u
sually tagged.
• General Ports
Ports set to General mode may be members of multiple VLANs. Each of
these VLANs may be configured to be tagged or untagged. This setting
applies to transmitted frames. Incoming untagged frames are classified
into the VLAN whose VID is the currently configured PVID.
Ingress filtering may be disabled on General ports. Ingress filtering is
enabled by defaul
t.
• Promiscuous Ports
A promiscuous port can communicate with all ports of the same Private
VLAN (PVLAN), including the isolated ports of the same PVLAN.