Definition – Tagged and Untagged VLAN
Tagged and untagged VLANs refer to different methods of handling VLAN traffic on network ports, particularly on switches. Here are the key differences between them:
1. Tagged VLAN
- Purpose: Tagged VLANs are used on trunk ports to carry traffic for multiple VLANs over a single physical link.
- VLAN Identification: Frames transmitted on tagged VLANs contain VLAN tags, which include VLAN identifiers (VLAN IDs). These VLAN tags enable switches to distinguish between different VLANs.
- Configuration: Trunk ports are typically configured to use tagged VLANs. Administrators specify which VLANs are allowed to traverse the trunk port, and the frames are tagged with the appropriate VLAN IDs as they pass through.
- Inter-Switch Communication: Tagged VLANs are essential for facilitating communication between switches and routers, especially when carrying traffic for multiple VLANs across the network.
- Example: Trunk ports connecting switches or routers usually utilize tagged VLANs to carry traffic for multiple VLANs across the network.
2. Untagged VLAN
- Purpose: Untagged VLANs are used on access ports to provide connectivity for devices within a single VLAN.
- VLAN Identification: Frames transmitted on untagged VLANs do not contain VLAN tags. The switch forwards these frames based on the VLAN configuration of the access port.
- Configuration: Access ports are typically configured to use untagged VLANs. Administrators assign a specific VLAN to each access port, and frames transmitted from devices connected to the port are forwarded within that VLAN without VLAN tags.
- End-User Devices: Untagged VLANs are commonly used to connect end-user devices such as computers, printers, IP phones, or access points to the network.
- Example: Access ports connecting end-user devices usually utilize untagged VLANs to provide connectivity within a single VLAN.
Key Differences between Tagged and Untagged VLAN
- Traffic Handling: Tagged VLANs are used for carrying traffic for multiple VLANs over trunk ports, while untagged VLANs are used for providing connectivity for devices within a single VLAN over access ports.
- VLAN Identification: Tagged VLANs use VLAN tags to identify VLANs, whereas untagged VLANs do not use VLAN tags; the VLAN membership is determined by the port configuration.
- Configuration: Trunk ports are configured to use tagged VLANs, while access ports are configured to use untagged VLANs.
- Use Cases: Tagged VLANs are used for inter-switch communication and carrying traffic for multiple VLANs, while untagged VLANs are used for connecting end-user devices within a single VLAN.
Summary – Tagged and Untagged VLAN
Tagged and untagged VLANs are essential concepts for managing network traffic within VLAN-enabled networks. Tagged VLANs append an additional VLAN header (tag) to Ethernet frames, identifying the VLAN to which the frame belongs. This is typically used on trunk ports connecting switches or other network devices, allowing multiple VLANs to be carried over a single physical link. This method improves VLAN management and reduces the number of required physical connections.
Untagged VLANs, in contrast, do not carry VLAN tags within Ethernet frames. Instead, frames are assigned to VLANs based on the port configuration, commonly used on access ports connecting end devices like computers and printers. This approach simplifies device configuration, as end devices do not need to be VLAN-aware. Both tagged and untagged VLANs are critical for efficient network segmentation, improving security by isolating traffic and enhancing performance by reducing broadcast domains and traffic congestion. Effective use of these VLAN methods ensures a well-organized, scalable, and secure network infrastructure.
in other word, Tagged VLANs are used for inter-switch communication, carrying multiple VLANs over a single link, while untagged VLANs are used for end device connections, simplifying device configuration. Both methods enable efficient network segmentation, enhancing security and performance.
Useful Links
https://sanchitgurukul.com/basic-networking
https://sanchitgurukul.com/network-security
