Can't connect another computer to a switch port that was already used by another computer
When you try to connect another connect antoher computer to a port that was already used, you get the following error message:
"03:07:04: %PORT_SECURITY-2-PSECURE_VIOLATION: Security violation occurred, caused by MAC address XXXX.XXXX.XXXX on port GigabitEthernet0/10."
(XXXX.XXXX.XXXX = the new computer's nic mac address)
This behaviour is by design when a port is restricted by Cisco's port-security feature.
You can use the following CLI command to "unlock" the specific port:
"clear port-security all interface GigabitEthernet0/10"