Enterasys 6000 User Guide

A Virtual Local Area Network is a group of devices that function as a single Local Area Network 
segment (broadcast domain). The devices that make up a particular VLAN may be widely 
separated, both by geography and location in the network.

The creation of VLANs allows users located in separate areas or connected to separate ports to 
belong to a single VLAN group. Users that are assigned to such a group will send and receive 
broadcast and multicast traffic as though they were all connected to a common network. 
VLAN-aware switches isolate broadcast, multicast, and unknown traffic received from VLAN 
groups, so that traffic from stations in a VLAN are confined to that VLAN.

When stations are assigned to a VLAN, the performance of their network connection is not 
changed. Stations connected to switched ports do not sacrifice the performance of the dedicated 
switched link to participate in the VLAN. As a VLAN is not a physical location, but a 
membership, the network switches determine VLAN membership by associating a VLAN with a 
particular port or frame type. 

 shows a simple example of a port-based VLAN. Two buildings house the Sales and 

Finance departments of a single company, and each building has its own internal network. The 
stations in each building connect to a SmartSwitch in the basement. The two SmartSwitches are 
connected to one another with a high speed link.