Allied Telesis AT-S63 - Manual (Page 428)

Chapter 19: Port-based and Tagged VLANs
428 Section III: VLANs
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 traffic generated by the nodes of a VLAN remains
within the VLAN.
With VLANs, you can segment your network through the switch’s AT-S63
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 decreases.
VLANs improve network perform 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.
In addition, because each VLAN constitutes a separate broadcast
domain, broadcast traffic remains within the VLAN. This too can
improve overall network performance.
❑ Increased security
Because data traffic generated by a node in a VLAN is restricted
only to the other nodes of the same VLAN, you can use VLANs to
control the flow of packets in your network and prevent packets
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.