Cisco VIRL is powerful network simulation tool. There are weeks when I run simulations 24/7 because of some projects or learning are ongoing. With VIRL you get almost the latest firmware for supported platforms. Almost – sometimes you have to wait for next release for a new firmware to be available. I experienced it a few months ago when with ASA 9.7(1) release Cisco introduced the route-based VPNs (VTIs). At this point VIRL users got the 9.6(2) release bundled into latest simulator release. In other simulation, you may want to use different ASAv firmware versions for various nodes, so your simulation is more similar to your production network.
Cisco VIRL uses real firmware in the simulations. I will show you how you can add different ASAv firmware and use it in parallel with the software available on VIRL repository.