Allied Telesis AT-S62 - Manual (Page 546)

Chapter 24: Port-based and Tagged Virtual LANs
546 Section V: 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
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:
ˆ 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 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.
Additionally, because each VLAN constitutes a separate broadcast
domain, broadcast traffic remains within the VLAN. This too can
improve overall network performance.
ˆ 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 packets in your network and prevent packets from flowing to
unauthorized end nodes.
ˆ 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.
But with VLANS, you can change the LAN segment assignment of an
end node connected to the switch through the switch’s AT-S62