Allied Telesis AT-S25 - Manual (Page 148)

Section II: Local and Telnet Mangement
148
The type of MAC address described above is referred to as a dynamic
MAC address. Dynamic MAC addresses are addresses that the switch
learns by examining the source MAC addresses of the frames received
on the ports.
Dynamic MAC addresses are not stored indefinitely in the MAC Menu.
The switch deletes a dynamic MAC address from the table if it does not
receive any frames from the node after a specified period of time. The
switch assumes that the node with that MAC address is no longer active
and that its MAC address can be purged from the table. This prevents
the MAC Address Table from becoming filled with addresses of nodes
that are no longer active.
The period of time that the switch waits before purging an inactive
dynamic MAC address is called the MAC aging time. This value is
adjustable on the AT-8316F or AT-8324 Switch. The default value is 300
seconds (5 minutes). For instructions on changing the aging timer, refer
to Changing the Aging Time on page 160.
The MAC Address Table can also store static MAC addresses. A static MAC
address, once entered in the table, remains in the table indefinitely and
is never deleted, even when the end node is inactive.
You might need to enter static MAC addresses of end nodes the switch
will not learn in its normal dynamic learning process, or if you wish a
MAC address to remain permanently in the table, even when the end
node is inactive.
Note
Due to chip set constraints, a port link state that changes from ‘up’
to ‘down’ will cause the addresses learned for that port group
(1)
to
be flushed.
(1)
A port group is considered one of the following:
Ports 1-8, ports 9-16, ports 17-24, ports A(x), ports B(x), where
A and B are the option module slots.