What is the primary role of the VLAN tag in Ethernet frames?

The primary role of the VLAN tag in Ethernet frames is to distinguish between multiple VLANs. VLAN, or Virtual Local Area Network, allows for segmenting a larger network into smaller, isolated sub-networks. Each frame that is transmitted can include a VLAN tag that identifies which VLAN the frame belongs to.

This tagging is essential in a switched Ethernet network where multiple VLANs might be present. By using VLAN tags, network switches can correctly forward traffic to the appropriate VLAN, ensuring that devices in one VLAN do not receive traffic meant for another. This enhances security and improves network performance by keeping broadcast traffic within its designated VLAN.

In essence, the VLAN tag provides the necessary information for the devices connected to the network to understand how to handle the traffic, thereby maintaining the separation and integrity of different network segments.