Allied Telesis AT-S41 - Manual (Page 89)

AT-S41 User’s Guide
89
VLAN Overview
A VLAN is a group of ports on an Ethernet switch that forms a logical
Ethernet segment. A VLAN can consist of all the ports on an Ethernet
switch or just a few ports. A VLAN can also span switches and consist of
ports from multiple Ethernet switches and stacks. The ports of a VLAN
form an independent broadcast domain where the traffic generated by
the end nodes of a VLAN remains within the VLAN and does not cross
over to the end nodes of other VLANs unless there is a connection
device, such as a router or Layer 3 switch.
With VLANs, you can segment your network through the switch’s
management software and so be able to group end 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
Marketing.
VLANs offer several important benefits:
❑ Improved network performance
Network performance often suffers as networks grow in size and
as data traffic increases. The more end nodes on each LAN
segment vying for bandwidth, the greater the likelihood overall
network performance will decrease.
VLANs improve network performance because VLAN data traffic
stays within the VLAN. The end nodes of a VLAN receive traffic
only from end nodes in the same VLAN. This reduces the need for
end nodes to handle traffic not destined for them. It also frees up
bandwidth within 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 an end node in a VLAN is restricted
only to the other end nodes in 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