Gns3 is a Graphical Network Simulator, the main purpose of which is to imitate complex networks and maximum approximate with the real networks' operation.
Gns3 was designed for the dedicated network hardware, for example switches or routers.
This software is an additional tool for network engineers working with CCNP, CCIE, Cisco CCNA, JNCIS, JNCIE, Juniper JNCIA and so on.
The distinctive feature of this tool is that it connects the virtual network to the real working networks or packet captures using Wireshark.
The user gains the ability to test network features and study for Redhat (RHCE, RHCT) and Microsoft (MSCE, MSCA) certifications.