Allied Telesis AT-S60 - Manual (Page 402)

Chapter 18: Virtual LANs
Section IV: VLANs 402
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 traffic
domain where the unicast, multicast, and broadcast packets generated
by the nodes of a VLAN remain 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 a LAN segment vying
for bandwidth, the more likely that overall network performance
decreases.
VLANs improve network performance because VLAN 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.
❑ Increased security
Since 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 instance, if an
employee changed departments, changing the employee’s LAN
segment assignment might require a change to the wiring at the
switches.
But with VLANS, you can change the LAN segment assignment of
an end node connected to the switch through the switch’s AT-S60
management software. VLAN memberships can be changed at
any time through the management software without moving the