Understanding VLANs: Tagged, Untagged, and Native VLANs

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What is VLAN ??

Virtual Local Area Networks (VLANs) are a fundamental concept in modern networking, allowing us to segment a physical network into multiple logical networks. By creating VLANs, we can isolate traffic, enhance security, and improve network performance. However, to fully utilize VLANs, it's crucial to understand the differences between tagged, untagged, and native VLANs.

Untagged VLANs

Untagged VLANs are the default configuration for most network devices. When a device sends a packet to a switch, it does not include any VLAN information. The switch then assigns the packet to a specific VLAN based on the port configuration. For example, if a port is configured as an untagged member of VLAN 10, any untagged packets received on that port will be associated with VLAN 10. Untagged VLANs are typically used for end devices that do not support VLAN tagging, such as workstations, IP cameras, and some servers. These devices simply want to communicate on the network without worrying about VLAN configurations.

Tagged VLANs

Tagged VLANs, also known as trunk VLANs, are used to carry traffic for multiple VLANs over a single link. When a switch sends a packet on a trunk link, it adds a VLAN tag to the packet, indicating which VLAN the packet belongs to. This allows the receiving switch to determine the appropriate VLAN for the packet. Trunk links are typically used between switches or between a switch and a router. They enable communication between different VLANs and allow for more efficient use of network resources.

Native VLANs

The native VLAN is a special VLAN used on trunk links to handle untagged packets. When a switch receives an untagged packet on a trunk link, it assumes that the packet belongs to the native VLAN. The native VLAN must be configured identically on both ends of the trunk link.  

 

It's important to note that packets that match the native VLAN are sent untagged on the trunk link. This ensures compatibility with devices that do not support VLAN tagging

 

 

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