A Switch can learn MAC address in two ways; manually or dynamically. In the manual option, we have to add the MAC addresses in the CAM or MAC table manually. In the dynamic option, the Switch learns and adds the MAC addresses in the MAC table automatically. The Switch stores the MAC table in the RAM.

When Switch receives a frame (1), it updates its MAC address table with the source MAC address and the port on which it received the frame (2). Switch broadcasts the frame using destination MAC ff:ff:ff:ff:ff:ff, to all ports (3), except the port on which the frame was received, if the destination MAC address is not found in the MAC address table (unknown).

When the Switch gets the reply back from the particular destination (4) the Switch will learn its MAC address and update its MAC address table with the destination MAC address-5. Switch already knows the MAC addresses of the participants, so doesn't need to flood data packets and actual data transfer happens.

The dynamically learned addresses are removed from the MAC Table after the MAC address age value has expired. This releases unused MAC addresses from the MAC address table for other active subscribers. In Cisco ME 2600X, the default value for aging the MAC address is 300 seconds or 5 minutes.