1. Introduction-7
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If the frame is tagged, the switch uses the tagged VLAN ID to
identify the broadcasting domain of the frame.
LEARNING
After VLAN classification, the switch checks the <source MAC
address, VLAN> pair in the switching database (SDB) to see
whether the <source MAC address, VLAN> pair is known.
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If it is unknown, the switch inserts the <source MAC address,
VLAN> into the SDB and learns the <source MAC address,
VLAN>.
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If it is known, the switch checks the <source MAC address,
VLAN> for a mismatched port ID. If the port ID associated
with the <source MAC address, VLAN> pair in the SDB is
different than the receiving port, the switch modifies the port
ID in the SDB and modifies its management database (MDB)
accordingly.