tagged vs untagged vlan

New Era

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12-10-2024

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Tagged vs. Untagged VLANs: A Comprehensive Guide

Virtual Local Area Networks (VLANs) are a fundamental technology in modern networking, allowing administrators to logically segment a network into smaller, isolated groups. This segmentation offers numerous benefits, including improved security, enhanced performance, and better network management. Within the realm of VLANs, there are two main categories: tagged and untagged. This article will delve into the key differences between these two types and explore their respective applications.

What are Tagged and Untagged VLANs?

Both tagged and untagged VLANs are methods of grouping devices on a network, but they differ in how they handle network traffic.

• Untagged VLANs: Devices on an untagged VLAN are assigned to that VLAN by default. Traffic from these devices is transmitted without any VLAN identification tags, making it appear as though it's on the native VLAN.
• Tagged VLANs: Devices on a tagged VLAN are explicitly identified with a VLAN tag attached to the network frames. This allows multiple VLANs to coexist on the same physical network segment, as the tags differentiate them.

The Key Differences

Practical Applications

Untagged VLANs are typically used for access ports, which are the connections where devices such as computers, printers, and phones connect to the network. By assigning these ports to an untagged VLAN, the devices automatically become members of that VLAN without any manual configuration.

Tagged VLANs, on the other hand, are commonly used for trunk ports. Trunk ports connect switches to each other and allow the transmission of multiple VLANs on a single physical link. This capability is crucial for connecting switches and building larger, segmented networks.

Example Scenario

Imagine a company with a network of employees and a separate network for guests. To isolate these two groups, you could create two VLANs: "Employees" and "Guests."

• Employees: Employees' computers would connect to access ports configured for the "Employees" VLAN (untagged).
• Guests: Guest devices would connect to access ports configured for the "Guests" VLAN (untagged).
• Connection: The switch connecting the two VLANs would have a trunk port (tagged) that allows traffic from both VLANs to pass through.

Benefits of Tagged and Untagged VLANs

• Security: VLANs limit network access, preventing unauthorized devices from accessing sensitive information on other VLANs.
• Performance: Segmenting the network reduces broadcast traffic and network congestion, improving overall performance.
• Management: VLANs simplify network administration by organizing devices logically, making it easier to manage and troubleshoot.

Choosing the Right VLAN Type

Selecting the appropriate VLAN type for each port depends on your specific network configuration and requirements. For access ports, untagged VLANs are generally the most practical choice, while trunk ports typically utilize tagged VLANs.

Additional Considerations

• Native VLAN: The native VLAN is a special VLAN on a trunk port that is associated with untagged traffic. It's important to configure the native VLAN carefully to avoid unexpected behavior.
• VLAN IDs: VLANs are identified by numbers, and different manufacturers may have slightly different implementations.

Conclusion

Tagged and untagged VLANs are essential tools for building secure, efficient, and manageable networks. Understanding the differences between these VLAN types and their practical applications allows network administrators to design and configure networks that meet the specific needs of their organization. By leveraging the power of VLANs, businesses can optimize their network performance, improve security, and simplify network administration.

Source:

This article utilizes information from the following Github repository: https://github.com/opennetworkingfoundation/SONiC/tree/master/docs/configuration_guide

Note: While this article provides a general overview of tagged and untagged VLANs, specific implementations and configuration details may vary depending on the networking equipment and software used. Always consult the documentation for your specific devices and network environment for accurate and up-to-date information.