Allied Telesis AT-S41 - Manual (Page 91)

AT-S41 User’s Guide
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VLAN Modifiers
The parts that make up a VLAN are:
❑ VLAN name
❑ VLAN Identifier
❑ Untagged ports
❑ Tagged ports
❑ Port VLAN Identifier
VLAN Name Every VLAN in your network should be given a name. The name should
reflect the function of the network devices that are be members of the
VLAN. Examples include Sales, Production, and Engineering.
VLAN Identifier Each VLAN in a network must be assigned a number. This number is
called the VLAN identifier (VID). This number will uniquely identify each
VLAN in your network. You assign the VID number when you create the
VLAN.
If a VLAN consists of ports located on only one AT-8350GB switch, you
must assign it a VID unique from all other VLANs in your network.
In instances where a VLAN spans multiple AT-8350GB switches, the VID
for the VLAN must be the same on each switch. This enables the
switches to recognize and forward frames belonging to the same VLAN
even though the VLAN spans multiple devices.
For example, if you had a VLAN titled Marketing that spanned three AT-
8350GB switches, you would assign the Marketing VLAN on each switch
the same VID.
Untagged and
Tagged Ports
There are two kinds of ports that you can create in IEEE 802.1Q-
compliant VLANs: tagged ports and untagged ports. The basic difference
between the two is that an untagged port can be a member of only one
VLAN at a time while a tagged port can be a member of multiple VLANs.
Untagged Ports
A VLAN that consists of only untagged ports is referred to as a port-
based VLAN. In order for frames from port-based VLANs to cross a VLAN
boundary, there must be a Layer 3 switch or router providing a
connection between the VLANs.