| Image Type | Emulator | Typical Use Case | Performance | |---------------------|----------------|----------------------------------------|----------------| | | Dynamips | Older Cisco routers (7200, 3600, 3725) | Lightweight | | IOS on IOU | IOU (L2/L3) | Cisco Layer 2/3 switching images | Fast, low RAM | | QEMU (IOSv, IOS-XE, vMX, etc.) | QEMU | Modern routers, higher feature set | Heavy, more RAM | | VirtualBox/VMware | GNS3 VM + QEMU| Full guest OS (e.g., VyOS, pfSense) | Depends on VM |
If you are serious about your studies, invest in a used Cisco router (like a 1841 or 2911) on eBay for a nominal fee, or secure a cheap support contract that grants access to the Cisco Software Center. This ensures your lab environment is stable, legal, and feature-complete. gns3 router images
These are specialized images used internally by Cisco. They are extremely lightweight and consume very little CPU and RAM, making them ideal for massive topologies. | Image Type | Emulator | Typical Use
These integrate into GNS3 exactly like a Cisco image—just add a Linux QEMU VM and install the OS. They are extremely lightweight and consume very little
A is a firmware file that contains the network operating system (NOS) of a physical router. When GNS3 loads this file, it emulates the CPU, memory, and bus architecture needed to run that OS unmodified.
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