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.
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