|  | 1.2 | Virtual LANs
| 1.2.3 | Frame tagging
Frame identification (frame tagging) uniquely assigns a user-defined ID to each frame. This technique was chosen by the IEEE standards group because of its scalability. VLAN frame identification is an approach that has been specifically developed for switched communications. This approach places a unique identifier in the header of each frame as it is forwarded throughout the network backbone. The identifier is understood and examined by each switch prior to any broadcasts or transmissions to other switches, routers, or end-station devices. When the frame exits the network backbone, the switch removes the identifier before the frame is transmitted to the target end station. Frame identification functions at Layer 2 require little processing or administrative overhead.