Self contained, you can run GNS3 directly on your computer.It also allows you to throw other vendors into the mix through VirtualBox or VMware Workstation integration. Using GNS3 you can effectively study from the CCNA level to the CCIE level across several tracks. Unlike something like Packet Tracer which emulates Cisco devices and provides common commands that a CCNA candidate might need, GNS3 is a network simulator that runs actual Cisco IOS so you have access to the full command line and features.It also allows for nodes to have external connectivity so you can connect your routers to connect to the internet or your local servers.
