How to test VLAN

How to test VLAN

Virtual Local Area Networks (VLANs) are a vital tool for any network administrator. They are implemented via message addressing modifications to the data link layer (OSI Layer 2) of a system in order to provide increased network performance, security, and customization. Understanding the basic usage, best practices, and troubleshooting methodology for VLANs should be a primary concern for every technician.

VLAN Basics

When configuring the network, the default state can be considered a solitary VLAN. When one device is attempting to communicate with another device without knowing its MAC (Media Access Control) address, it broadcasts the message to the IP of the other device using protocols such as the Address Resolution Protocol (ARP) or the Dynamic Host Configuration Protocol (DHCP). If the network is a room in which all of the devices exist, the router or switch is a messenger who knows that its intended listener is somewhere in the room, but not the exact location. To deliver the message, they shout it out along with the intended recipient’s name, hoping that it makes its way there.

Because of the loud nature of a broadcast message, it has inherent security and performance issues. Since every device on the network hears the message, they have to spend the effort to determine if the message is intended for them. To return to the room analogy, the shouted message can be heard by anyone in the room and has the potential to drown out other conversations, or at least delay them for a moment.

By properly configuring a VLAN, the data is handled in a much more sensible manner. Tags are placed around the data packets to indicate which VLAN will receive the traffic, allowing other devices to filter out the noise. The end result is an effective increase in total throughput for the network. If the event coordinator of the party this hypothetical room is being used for is considered to be the router with Internet access, the VLAN would operate like a guest list that details each party goer so the coordinator doesn’t have to let the entire room know that one guest’s significant other is upset that they stayed out late without phoning home.

Common VLAN Uses

A typical usage of VLAN tagging is to separate data traffic from Voice over IP (VoIP) traffic. The real-time nature of voice communication is more susceptible to performance degradation from a busy network, so placing these data packets in their own VLAN can keep your Skype calls understandable and tolerable even while the network is under heavy use.

Security is another major benefit of a VLAN. Minimizing the number of broadcast recipients lowers the potential for unwanted users gaining access to sensitive information.

VLANs also improve the administrative ease of configuring the network by moving the physical task of rewiring devices to different routers and switches to a data-based system that can be altered from a workstation with appropriate access. This also eliminates the need for extra devices, reducing the cost of implementing the network.

Take Control of the Network with the Net Prowler & Net Chaser

For every type of network from the home to the workplace, the Net Prowler and Net Chaser comes with the tools necessary to properly detect and configure all of the various settings needed to optimize performance. The LLDP and CDP readout will display VLAN information (including the VLAN ID and subtype) for the device if it exists, allowing you to quickly map both the actual and virtual setup of the network. Streamline your network diagnostics by keeping the Net Prowler or Net Chaser on hand while delving into the virtual depths of the network.