Allied Telesis AT-S39 - Manual (Page 119)

AT-S39 User’s Guide
119
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. A router or Layer 3 network device is required in order
for traffic to cross a VLAN boundary.
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 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 a VLAN. This too can
improve overall network performance.
❑ Increased security
VLANs can be used to control the flow of packets in your network
and prevent packets from flowing to unauthorized end nodes.
Data traffic generated by a node in a VLAN is restricted only to the
other nodes of the same VLAN
❑ 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.