BENEFITS AND RESTRICTIONS VLANS VIRTUAL LOCAL AREA NETWORKS

The primary benefit of the port based VLAN technology is the localization of traffic that it provides. This function can offer improvements in security and performance to stations assigned to a VLAN.

While the localization of traffic to VLANs can improve security and performance, it imposes some restrictions on network devices that participate in the VLAN. If a switch is operating in the “secure mode,” a group of users assigned to a single VLAN can communicate with one another freely, but cannot communicate with users on other VLANs without the services of a Network Layer (OSI Layer 3) routing device to make the connection between the VLANs. In the “open” mode, this restriction does not apply.

In order to set up a VLAN, all the network switch devices that are assigned to the VLAN must support the prestandard IEEE 802.1Q specification for port based VLANs. Before you attempt to implement a VLAN strategy, ensure that the switches under consideration support the 802.1Q specification.