Allied Telesis AT-S79 - Manual (Page 74)

Chapter 7: Virtual LANs
74 Section I: Using the Menus Interface
Port-based VLAN Overview
As explained in “VLAN Features” on page 72, a VLAN consists of a group
of ports on one or more Ethernet switches that form an independent traffic
domain. Traffic generated by the end nodes of a VLAN remains within the
VLAN and does not cross over to the end nodes of other VLANs unless
there is an interconnection device, such as a router or Layer 3 switch.
A port-based VLAN is a group of ports on a Gigabit Ethernet switch that
form a logical Ethernet segment. Each port of a port-based VLAN can
belong to only one VLAN at a time.
A port-based VLAN can have as many or as few ports as needed. The
VLAN can consist of all the ports on an Ethernet switch, or just a few ports.
A port-based VLAN also can span switches and consist of ports from
multiple Ethernet switches.
Note
The AT-GS950/16 and AT-GS950/24 switches are preconfigured
with one port-based VLAN, called the Default VLAN. All ports on the
switch are members of this VLAN.
A port-based VLAN consists of the following parts:
ˆ VLAN name
ˆ VLAN Identifier
ˆ Untagged ports
ˆ Port VLAN Identifier
VLAN Name
To create a port-based VLAN, you must give it 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
Every VLAN in a network must have a unique number assigned to it. This
number is called the VLAN identifier (VID). This number uniquely identifies
a VLAN in the switch and the network.
If a VLAN consists only of ports located on one physical switch in your
network, you assign it a VID different from all other VLANs in your
network.
If a VLAN spans multiple switches, then the VID for the VLAN on the
different switches should be the same. The switches are then able to
recognize and forward frames belonging to the same VLAN even though
the VLAN spans multiple switches.