The Book of GNS3

GNS3 is open source software that emulates Cisco router and switch hardware to simulate complex networks. You can use GNS3 on any computer to experiment with various router configurations, study for that next big Cisco certification, or build the ubernetwork of your wildest dreams - all without plugging in a single physical network cable.

The Book of GNS3 will teach you how to harness the powerful GNS3 software to create your own virtual networks with Cisco and Juniper devices. Hands-on tutorials throughout show you how to:
-Configure Cisco IOS and ASA devices in GNS3
-Add Juniper routers to your projects with VirtualBox and QEMU
-Connect GNS3’s hub, switch, and cloud devices to physical hardware
-Integrate Cisco IOU virtual machines for advanced switching features
-Simulate a Cisco access server to practice managing devices
-Build bigger labs by distributing project resources across multiple computers

Why set up all of that expensive physical hardware before you know whether it will all work together? Learn how to build virtual networks with The Book of GNS3, and stop reconfiguring your lab every time you want to test something new.