Chapter 13. Optimizing network performance by using port channels
Remember from the last chapter that you have two connections between Switch1 and Switch2, and that the Spanning Tree Protocol (STP) allows traffic to traverse only one of those links. This prevents bridging loops but has a downside: it consumes an additional port on each switch without letting you use the bandwidth of those ports.
A port channel—also known as an EtherChannel—lets you have the best of both worlds. It allows traffic to flow simultaneously across both links while still preventing bridging loops.
As you go through this chapter, you’ll learn how to configure a port channel to achieve the configuration shown in figure 13.1.
Notice that the port channel consists of FastEthernet0/23 and 0/24 and is called Port-channel1. When you configure a port channel on a switch, the switch creates a logical or virtual interface to represent the port channel.
In keeping with Cisco tradition, a port channel may also be called an Ether-Channel, a bundle, or a port group. I’ll use the term port channel most of the time, but in the configuration commands and output, you’ll see some of these other terms pop up.