| Feature | IOU | Cisco Packet Tracer | Cisco IOL | | :--- | :--- | :--- | :--- | | | Unix (Solaris) based | Windows/Mobile App | Linux based | | Realism | High (CLI identical to real IOS) | Low (Limited command set) | Very High | | Switching | Good L2 support | Basic switching | Excellent L2/L3 support | | Performance | Very Fast | Very Fast | Very Fast | | Availability | Unofficial/Leaked | Free (Official) | Unofficial/Leaked |
stands for IOS on Unix . It is a Cisco proprietary application compiled for the SPARC architecture (later ported to Linux x86). Unlike Dynamips, which emulates the physical hardware (motherboard, CPU, memory) to run a generic IOS image, IOU is a version of the Cisco IOS compiled to run natively as a Unix/Linux process. gns3 iou
Avoid trying to run IOU locally on Windows via Cygwin; it is prone to crashes. The GNS3 VM is the gold standard. | Feature | IOU | Cisco Packet Tracer