How Vlan identifies from which port the data has come ?

[arunsenthil.ece]

Hi ,

We know that more number of ports can be configured to same vlan. How vlan distinguish between the ports ? How vlan knows from which port this frame has come ? in tagging we add the vlan id to the frame and not any other info ? little confused on how this haapens ??

[Joseph W. Doherty]

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A VLAN doesn't really distinguish between ports.  A switch does, though, "remember" (for some time) the source MAC as frames enter its ports.

Tagged frames may contain more than VLAN ID, such as L2 CoS.