Like Dynamips, Qemu is an emulator. In fact, it gets its name by claiming to be a Quick EMUlator. And it is actually able to emulate many more devices than Dynamips, such as Linux servers and Windows PCs, but in the GNS3 environment it is most often used to emulate other networking devices such as Cisco ASAs and Juniper routers.
Also like Dynamips, you will need more than just Qemu. You will also need a binary copy of the operating system you want Qemu to emulate. And because you want to use GNS3 to configure connections between your Qemu devices and even your Dynamips devices, you will also need a third piece of code called qemuwrapper
, which is included with your GNS3 install.
And one more thing. The version of Qemu you run has to be aware of the types of interfaces used in GNS3. GNS3 creates UDP tunnels between devices to allow them to communicate (see Chapter 6, Peeking under the GNS3 hood), so you need a specially patched version of Qemu that knows...