Overview
An important feature of Ethernet switching is the virtual local-area network (VLAN). A VLAN is a logical grouping of devices or users. These devices or users can be grouped by function, department, or application despite the physical LAN segment location. Devices on a VLAN are restricted to only communicating with devices that are on their own VLAN. Just as routers provide connectivity between different LAN segments, routers provide connectivity between different VLAN segments. Cisco is taking a positive approach toward vendor interoperability, but each vendor has developed its own proprietary VLAN product and it may not be entirely compatible.

VLANs increase overall network performance by logically grouping users and resources together. Businesses often use VLANs as a way of ensuring that a particular set of users are logically grouped regardless of the physical location. Therefore, users in the Marketing department are placed in the Marketing VLAN, while users in the Engineering Department are placed in the Engineering VLAN.

VLANs can enhance scalability, security, and network management. Routers in VLAN topologies provide broadcast filtering, security, and traffic flow management.

VLANs are powerful tools for network administrators when properly designed and configured. VLANs simplify tasks when additions, moves, and changes to a network are necessary. VLANs improve network security and help control Layer 3 broadcasts. However, improperly configured VLANs can make a network function poorly or not function at all. Understanding how to implement VLANs on different switches is important when designing a network.

Students completing this module should be able to:

  • Define VLANs
  • List the benefits of VLANs
  • Explain how VLANs are used to create broadcast domains
  • Explain how routers are used for communication between VLANs
  • List the common VLAN types
  • Define ISL and 802.1Q
  • Explain the concept of geographic VLANs
  • Configure static VLANs on 29xx series Catalyst switches
  • Verify and save VLAN configurations
  • Delete VLANs from a switch configuration