Well, I suppose it depends on what switch manufacturer and model you’re using. For the Cisco 29xx series of switches there is a 5 minute timer in the MAC address database which (if the address was dynamically learned) will timeout unless the MAC address shows up on another port in which case the switch will automatically move it to the new port. When you use the command
switchport port security mac-address (MAC) or (sticky) a PERMANENT entry is created in the MAC address table which must be removed by running the command above with NO in front of it due to the fact that there is NO timeout on permanent addresses. I hope that helps. – brent mossberger
If you’re using an HP managed switch, you can designate how many MAC addresses can be allowed per port and then just add them to each port’s database as required. This is handy if a hub or access point is attached to a particular port.