These commands really are probably the most popular because they prevent random
users from connecting to a specific switch or access point that’s in their office. The
maximum setting is 1, which is the port security default that’s immediately set on a port
when it’s enabled. Sounds okay, but the drawback to this is that it only allows a single
MAC address to be used on the port, so if anyone, including you, tries to add another host
on that segment, the switch port will immediately shut down. And when that happens,
you have to manually go into the switch and re-enable the port by cycling it with a
shutdown and then a no shutdown command.