Allied Telesis AT-S81 - Manual (Page 98)

Chapter 9: Virtual LANs
98 Section I: Using the Menus Interface
VLAN Overview
This VLAN overview contains the following sections:
ˆ “VLAN Name,” next
ˆ “VLAN Identifier” on page 98
ˆ “VLAN Port Members” on page 98
ˆ “Port VLAN Identifier” on page 98
ˆ “Incoming and Outgoing Tagged and Untagged Frames” on page 99
ˆ “Guidelines for Creating a VLAN” on page 100
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. The factory VID is 1 for all ports.
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.
For example, if you had a VLAN titled Marketing that spanned three
AT-8000/8POE Fast Ethernet switches, you would assign the Marketing
VLAN on each switch the same VID.
Port VLAN
Identifier
The Port VLAN Identifier (PVID) is the VLAN identifier associated with a
specific port. The PVID provides a VLAN assignment for each untagged
frame received by the switch. (See “Incoming and Outgoing Tagged and
Untagged Frames” on page 99.) The switch internally associates the
untagged frame with the VID that is equal to the PVID. The switch then
forwards this frame to one of the other member ports of that VLAN. The
default PVID value is 1.
VLAN Port
Members
You need to specify which ports on the switch are to be members of a
VLAN. A port can be specified as a member of one or more VLANs up to
255, the maximum number of VLANs supported by the switch. The factory
default VID is 1. Therefore, each port is initially configured to be a member
of VLAN 1, which is known as the default VLAN.