Allied Telesis AT-S39 - Manual (Page 91)

AT-S39 User’s Guide
91
VLAN Overview
A VLAN is a group of ports on an Ethernet switch that form a logical
Ethernet segment. The ports of a VLAN form an independent broadcast
domain where the traffic generated by the nodes of a VLAN remains
within the VLAN.
With VLANs, you can segment your network through the switch’s
management software and so be able 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.
For example, you could create separate VLANs for the different
departments in your company, such as one for Sales and another for
Accounting.
VLANs offer several important benefits:
❑ Improved network performance
Network performance often suffers as networks grow in size and
as data traffic increases. The more nodes on each LAN segment
vying for bandwidth, the greater the likelihood overall network
performance will decrease.
VLANs improve network perform because VLAN data traffic stays
within the VLAN. The nodes of a VLAN receive traffic only from
nodes of the same VLAN. This reduces the need for nodes to
handle traffic not destined for them. It also frees up bandwidth
within all the logical workgroups.
Additionally, since each VLAN constitutes a separate broadcast
domain, broadcast traffic remains within the VLAN. This too can
improve overall network performance.
❑ Increased security
Since data traffic generated by a node in a VLAN is restricted only
to the other nodes of the same VLAN, VLANs can be used to
control the flow of data in your network and prevent data from
flowing to unauthorized end nodes.
❑ Simplified network management
VLANs can also simplify network management. Before the advent
of VLANs, physical changes to the network often had to been
made at the switches in the wiring closets. For example, if an
employee changed departments, changing the employee’s LAN
segment assignment might require a change to the wiring at the
switches.