Go to Edit > Preferences > IOS on UNIX .
Building a robust lab with a is the most cost-effective way to master complex networking protocols. By utilizing legal sources like Cisco CML and properly configuring appliances in GNS3, you can create a virtual replica of any enterprise network, preparing you for the real-world challenges of a network engineer. gns3 full pack images
These are the traditional Cisco router images that run on the Dynamips emulator. They are relatively light on CPU and memory, making it possible to run many of them in a single topology. GNS3’s documentation recommends the series for their proven stability in simulations. Go to Edit > Preferences > IOS on UNIX