Chapter 4. Managing switch ports
A network can consist of many different kinds of devices: PCs, IP phones, printers, servers, wireless access points, and even other switches. The one thing these devices all have in common is that they physically connect to a switch, specifically, the Ethernet port of a switch.
Although Cisco sometimes refers to ports as interfaces, I’m going to call them ports because that’s how most people know them. Although plugging a device into a switch port is a trivial task, the magic behind how data gets transferred between a device and a switch is anything but trivial.
See if any part of this story sounds familiar: I used to work for a company that had offices scattered around the country. Each office had a few switches, a firewall, and a router, but no IT people to manage it hands-on. Whenever an employee moved desks, or a new employee came on board, a non-IT person (usually a manager) would plug the employee’s IP phone into the network jack in their cubicle. To their surprise, the phone would often not even turn on. Other times, it would turn on but wouldn’t work. Or maybe the phone would work, but the computer (which was plugged into the phone) would not be able to access the network.