A Virtual Local Area Network (VLAN) enables the division of a physical network into multiple logical networks. Each of these logical networks acts as an independent LAN with its own broadcast domain. As a result, devices in different VLANs cannot communicate directly with each other, even if they are connected to the same physical switch.
Distinction between physical and virtual LANs
A physical LAN separates networks physically with separate cables and switches. This method is often cumbersome, expensive, and inflexible, especially in large or dynamically growing organizations. VLANs offer the possibility to divide a physical network into multiple logical segments without changing the physical infrastructure. This increases the flexibility and efficiency of network usage and allows administrators to manage network segments easily via software.
Example: In an office building, a single switch can support multiple VLANs, such as one VLAN for employee PCs, one for IP telephony, and one for visitors. Although these networks are physically connected to the same switch, they are logically separated and can have different security policies and access rights.
Advantages and areas of application
- Efficiency: VLANs reduce data traffic by limiting broadcasts to the relevant VLAN.
- Flexibility: Devices can be easily moved from one network segment to another without making physical changes.
- Scalability: VLANs allow for easy expansion of the network, as new devices can be logically added.
VLAN Security
VLANs provide improved security by segmenting the network into isolated parts. This prevents sensitive information within one segment from reaching other network areas. An example of this is a separate VLAN as guest access (guest WiFi). Visitors to a company thus have access to the internet but not to the internal company network. This protects sensitive company data from unauthorized access.
