If you are not an authorized Cisco employee or trusted partner, usage of Cisco IOU is potentially a legal gray area. However, the legality of the source of Cisco images for GNS3 is questionable. One key advantage that Cisco IOU has is that it does not require nearly as much resources as GNS3 and VIRL would require. IOU was built as a native Solaris image and runs just like any other program. It is a fully working version of IOS that runs as a user mode UNIX (Solaris) process. Cisco IOS on UNIX (IOU) is another option for running Cisco routers in virtual environment. GNS3is a well-known free network simulation platform that has been around for many years. In this article, I will compare Cisco VIRL with the most commonly used GNS3 and explain my top four reasons why Cisco VIRL is better than GNS3. They all have their advantages and disadvantages. There are several network simulation and emulation tools available, for example, Packet Tracer, GNS3, Cisco VIRL, Cisco IOU and UNetLab. If the production network is going virtual, for fellow network engineers, certification students and Cisco Academy trainers, there is no reason to use physical devices for your lab testing and learning purposes. Started from server and storage virtualizations, to Software Defined Networking (SDN), the entire datacenter technology is trending to the direction of moving away from physical infrastructure.

In the recent years, virtualization technology has advanced to the point that nearly everything can be virtualized.

Iosv startup config.img cisco gns3