Virtual LANs
46
VLAN Features
A Virtual Local Area Network (VLAN) is a logical grouping of devices on
different physical LAN segments that allows users to communicate as if
they were physically connected to a single LAN, independent of the
physical configuration of the network.
With VLAN switch management software, you can segment your
network and group end-nodes with related functions into their own
separate, logical LAN segments. For example, the marketing personnel
in you company may be spread through-out a building. Assigning
marketing to a single VLAN allows marketing personnel to share
resources and bandwidth as if they were connected to the same
segment. The resources of other departments can be visible to the
marketing VLAN members, accessible, or accessible only to specified
individuals.
A few benefits of a VLAN architecture are described in the following
sections.
Increased
Performance
In traditional Layer 2 switched networks, broadcast packets are sent to
each and every individual port. VLANs address the limitations of
standard switch segmentation by containing broadcast as well as end-
node-to end-node traffic.
Grouping users into logical networks limits broadcast traffic to users
performing similar functions or users within individual workgroups. High
traffic, the danger of broadcast storms, router latency, and data
collisions are significantly reduced, and the efficiency of the entire
network is improved.
Improved
Manageability
VLANs provide a fundamental improvement in the design,
administrations, and management of LANs. Before VLANs, physical
changes to a network were made at the switch in the wiring closet.
For example, if an employee transferred to a new department, changing
that employee’s LAN segment assignment often required a physical
wiring change at the switch.
As a software-base solution, VLANs eliminate the restriction of existing
network design and cabling infrastructure and allow the centralized
configuration of switches located in many different locations. VLAN
memberships are changed quickly and efficiently from the management
console rather than in a wiring closet.
