This is the client part of GNS3 and is graphical user interface (GUI).

GNS3 consists of two software components:

Recommendation: If you are using an older version of GNS3, it is recommended that you upgrade to the current stable release of GNS3. You are now able to test interoperability between many vendors and even try out esoteric setups using network technologies with SDN, NFV, Linux and Docker. However, many other commercial and open source vendors are supported today in GNS3. Cisco is often discussed because that is what most network engineers are interested in learning about. GNS3 does not only support Cisco devices.

Go here to see a list of appliances available: Originally only emulating Cisco devices using software called Dynamips, GNS3 has now evolved and supports many devices from multiple network vendors including Cisco virtual switches, Cisco ASAs, Brocade vRouters, Cumulus Linux switches, Docker instances, HPE VSRs, multiple Linux appliances and many others. GNS3 has allowed network engineers to virtualize real hardware devices for over 10 years. Because of that original work, you can today use to help you do the same without paying for expensive hardware. 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 the Cisco CCNA, but also help you test and verify real world deployments. GNS3 is used in companies all over the world including Fortune 500 companies. By joining the GNS3 community you will be joining fellow students, network engineers, architects and others that have downloaded GNS3 over 10 million times to date. It is actively developed and supported and has a growing community of over 800,000 members. GNS3 is open source, free software that you can download from GNS3 allows you to run a small topology consisting of only a few devices on your laptop, to those that have many devices hosted on multiple servers or even hosted in the cloud.

GNS3 is used by hundreds of thousands of network engineers worldwide to emulate, configure, test and troubleshoot virtual and real networks.

Configure GNS3 to use an additional remote server.

How to use applications with the GNS3 Web interface.

Install an appliance from the GNS3 Marketplace.

Cisco ios images for gns3 downloads