Crash Course: VLANs

These resources will provide you with all the information needed to understand VLANs, from what they are to what they do and how they do it.

By allowing users to be grouped by department, type of user, or virtually any other criteria, VLANs can be a great asset to network administrators and managers. Learn how with this new and improved VLANs crash course.


A virtual (or logical) LAN is a local area network with a definition that maps workstations on some other basis than geographic location (for example, by department, type of user, or primary application). The virtual LAN controller can change or add workstations and manage loadbalancing and bandwidth allocation more easily than with a physical picture of the LAN. Network management software keeps track of relating the virtual picture of the local area network with the actual physical picture.

Read the full definition here, courtesy of


Virtual LAN basics
Expert Chris Partsenidis runs down the basics of virtual LANs.

Popular VLAN attacks and how to avoid them
Learn how to secure a VLAN from popular attacks such as the VLAN hopping attack.

The Lippis Report Volume 44: Secure domains and VLANs
Segmenting networks into security domains will become increasingly important as networks move toward a trusted model.

Read more VLAN-related tips here.


Will a VLAN help secure my small network?
Expert response: Setting up a VLAN for such a small home office network would be very expensive in terms of hardware and setup required...

What kind of security is available for VLANs?
Expert response: High-security users can be grouped into a VLAN, possibly on the same physical segment, and no users outside of that VLAN can communicate with them...

How do I enable VLAN grouping?
Expert response: When a port is configured to "trunk" mode, it will carry information belonging to all VLANs. These ports are then called "trunk ports" and...

Ask one of our experts your VLAN-related questions.


VLAN best practices
This whitepaper discusses VLAN challenges, best practices, tagging and tagging technologies, maintaining VLANs and how good documentation practices will help troubleshoot problems and optimize VLAN performance.

Virtual LAN security best practices
The purpose of this paper is to present in a comprehensive way all of the recommendations that Cisco engineers have accumulated to aid with the proper configuration of VLANs on Cisco switches.

Cisco field manual: Catalyst switch configuration -- VLANs and trunking
This excerpt from the book "Cisco Field Manual: Catalyst Switch Configuration," by David Hucaby and Steve McQuerry, focuses on virtual local area networks (VLANs). Learn about VLAN configuration, port membership, trunking methods and protocols.

View more VLAN-related webcasts and white papers.

This was last published in August 2005

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