Allied Telesis AT-S20 - Manual (Page 88)

Security/Source Address Table
6-14
Automatic: Learning On/Security Off
The automatic mode is the default setting. When in “automatic”
mode, the SAT is in an “unlocked” state and is updated each time a
port receives a packet from a new source address. The SAT address
table can store 2K of MAC addresses.
When the switch is in a learning mode, the software:
❑ Monitors the MAC source address as frames come into each
port
❑ Compares the incoming source addresses to entries in the SAT
table
❑ Updates the SAT table by storing the new MAC address
Note
If you do not lock the SAT table, it will not be saved when the switch
is reset.
Most users typically keep the source address learning mode ON to
continuously update the MAC address table. Information in the table
is useful for inventory control, based on MAC addresses of the
devices connected to the module. As an option, you can manually
turn learning OFF and go to a secure mode if you want to restrict the
module only to specific MAC addresses. Once this process is
complete, all MAC addresses become static addresses and will stay in
the MAC address table until the table is cleared or until the address is
deleted.