Sound too good to be true? Well, there really is not a catch, but one needs to be aware of the resource requirements to run a bunch of the devices listed above. VIRL states the min CPU and RAM as follows - Four CPU cores and 8GB of DRAM that can be allocated to the VIRL VM (more resources allows for larger simulations). This is certainly true. While the product caps you at 15 devices total (excluding the unmanaged switches it provides), you would need a bunch of RAM to actually achieve that 15 number. I use an i7 iMac with 32 GB of RAM in order to run nice 15 device topologies. Thankfully, RAM prices keep falling.