Management - Virtual LAN (VLAN)
A VLAN is a group of switch ports designated by the switch as belonging
to the same broadcast domain. More specifically, VLANs can be seen as a
group of end-stations, perhaps on multiple physical LAN segments, which
are not constrained by the physical location and can communicate as if
they were on a common LAN. This feature allows workgroups to be defined
on the basis of their logical function instead of their physical
location, and does not require re-cabling. VLAN helps isolate broadcast
traffic and increase security, so as to increase bandwidth to each
There are four way to define VLAN membership: port grouping, MAC-layer
grouping, network-layer grouping, and IP multicast grouping.
Port-Based VLAN (802.1q)
Port grouping is the most common method of defining VLAN membership, and
its configuration is straightforward. But, when a user moves from one
port to another, it takes a network manager to manually reconfigure VLAN
membership. With manual VLAN configuration, the network administrator,
enabling a high degree of control, controls both the initial setup and
all subsequent moves or changes. Most of VLAN switches are compliant
with IEE802.1q Port-based VLAN standard.
Trunking is a very useful feature to multiply network bandwidth within
your LAN. By establishing a connection that allows network devices to
communicate using multiple links in parallel, data can be transferred at
multiple bandwidths. For example, Ether-FSH24RS can set up 4-10/100Base
ports as a trunking group thus link aggregate becoming 800Mbps.
Class of Service (CoS, 802.1p)
Class of Service applies to traffic prioritization and a small number of
individual classes. 802.1p allows users or programs to put priorities
(normally two levels: high or low) on a particular network transaction.
When network traffic congestion occurs, the data tagged with
"high" priority will get through first. 802.1p also
limits the extend of high bandwidth multicast traffic within a bridged
LAN. It works in junction with 802.1q VLAN function for tagging and