At some time you will need to connect multiple routers together, as you would on a physical Ethernet switch or a WAN switch such as a frame-relay or an ATM switch. You could use additional router nodes to perform these functions, but in an effort to provide this functionality with much less resource usage, Dynamips (and hence GNS3) created its own range of virtual devices that do an excellent job of providing virtual connections between devices.
This section will show you not only how to add a generic Ethernet switch, but also how to add additional interfaces to your routers using two different methods —manual and automatic.
Probably the most useful of these switches will be the Ethernet switch. You will get to explore this in more detail in Chapter 3, Enhancing GNS3. In this exercise, you will add two switches, and connect each of your routers to each of the switches, and at the same time add an extra line card to your routers to be able to...