To switch frames between LAN ports efficiently, the switch maintains
an address table. When the switch receives a frame, it associates the media
access control (MAC) address of the sending network device with the LAN port on
which it was received.
The switch dynamically builds the address table by using the MAC
source address of the frames received. When the switch receives a frame for a
MAC destination address not listed in its address table, it floods the frame to
all LAN ports of the same VLAN except the port that received the frame. When
the destination station replies, the switch adds its relevant MAC source
address and port ID to the address table. The switch then forwards subsequent
frames to a single LAN port without flooding all LAN ports.
You can also enter a MAC address, which is termed a static MAC
address, into the table. These static MAC entries are retained across a reboot
of the switch.
In addition, you can enter a multicast address as a statically
configured MAC address. A multicast address can accept more than one interface
as its destination.
The address table can store a number of unicast and multicast address
entries without flooding any frames. The switch uses an aging mechanism,
defined by a configurable aging timer, so if an address remains inactive for a
specified number of seconds, it is removed from the address table.