Dell PowerConnect 8024 User Configuration Manual page 490

be active on a port, you can set the number of allowable dynamic addresses to
one. After the MAC address of the first device is learned, no other devices will
be allowed to forward frames into the network.
When link goes down on a port, all of the dynamically locked addresses are
cleared from the source MAC address table the feature maintains. When the
link is restored, that port can once again learn addresses up to the specified
limit.
The port can learn MAC addresses dynamically, and you can manually specify
a list of static MAC addresses for a port.
490
Configuring 802.1X and Port-Based Security