GNS3 has enabled network engineers to virtualize real hardware devices for over 10 years. Thanks to this original work, you can now use it to help you do the same without paying for expensive equipment. Jeremy Grossman, the original developer of GNS3 originally created the software to help him study for his CCNP certifications. GNS3 can help you prepare for certification exams such as Cisco CCNA, but also test and verify real-world deployments. GNS3 allows you to run a small topology consisting of only a few devices on your laptop, to those with many devices hosted on multiple servers or even hosted in the cloud. GNS3 is used by thousands of thousands of network engineers around the world to emulate, configure, troubleshoot, and test virtual and real networks.
