AT-2716POE Fast Ethernet Fiber & PoE Adapter Installation and User’s Guide
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The AT-2716POE adapter is IEEE 802.1Q-compliant and is designed to
support virtual LANs (VLANs) and tagged packets. A VLAN is an
independent traffic domain where traffic generated by the nodes of a
VLAN is restricted only to nodes that are members of the same VLAN.
Traffic within a VLAN cannot cross over a VLAN boundary unless there is
an interconnection device, such as a router or a Layer 3 switch in the
network.
Often, VLANs are used to group nodes with related functions into their
own separate, logical LAN segments. These VLAN groupings can be
based on similar data needs or security requirements. In addition, VLANs
can increase network performance and security by restricting traffic to
specific devices or areas of a network.
A tagged VLAN (IEEE 802.1Q) contains one or more network links that
carry traffic from more than one VLAN. The VLAN traffic is identified by a
header tag, or simply a tag, that follows the source and destination
addresses in a packet. The tag contains a VLAN identifier (VID) that
uniquely identifies the VLAN to which a packet belongs. The AT-
2716POE adapter is capable of reading the header tag in tagged packets
as they arrive on the port, as well as adding tags to packets when
transmitting packets.
Before a network adapter card can handle tagged packets, you must
configure it by specifying the appropriate VIDs of the VLANs whose
tagged packets the adapter is to process.
If the network adapter card handles tagged traffic from more than one
VLAN, you can use the AT-2716POE AT-Mux Configuration utility, which
you can download from the Allied Telesis website. This utility allows you
to assign a VIDs to each adapter port enabling a network adapter card to
process tagged traffic from different VLANs.
The following list briefly outlines the behavior of a network adapter card
when handling tagged and untagged VLAN traffic:
An adapter where no VIDs have been assigned accepts and transmits
only untagged packets. (An untagged packet does not contain a
header tag and, consequently, lacks VLAN identification.) The adapter
discards any tagged packets that arrive on the port. Both the fiber and
copper port communicate on the same network.
An adapter where at least one VID has been assigned accepts only
those tagged packets with header tags that match the assigned VIDs