1. explain
- Graphical Network Simulator-3
- Real-time network simulation without network hardware
- run & test multiple network hardware vendors(ex : cisco)
2. Install
2.1 Download(URL : https://www.gns3.com)

2.2 create Account -> login(If you already have an account, click "Login".)

2.3 setup

2.4 start GNS3
end.