Your CCNA studies are going to include quite a bit of information about switches, and for good reason. if you don’t understand basic switching theory, you can’t configure and troubleshoot Cisco switches, either on the CCNA exam or in the real world. That goes double for trunking!
Trunking is simply enabling two or more switches to communicate and send frames to each other for transmission to remote hosts. There are two major trunking protocols that we need to know the details of for exam success and real-world success, but before we get to the protocols, let’s discuss the cables we need.
Connecting two Cisco switches requires a crossover cable. As you know, there are eight wires inside an ethernet cable. In a crossover cable, four of the cables “cross over” from one pin to another. For many newer Cisco switches, all you need to do to create a trunk is connect the switches with a crossover cable. For instance, 2950 switches dynamically trunk once you connect them with the right cable. If you use the wrong cable, you’ll be there a while!
There are two different trunking protocols in use on today’s Cisco switches, ISL...