Most network devices run proprietary software that you can only obtain from the vendor when you have an active subscription in place. This can make testing or learning with this software difficult, even if an emulator for the network devices is available. Fortunately for us, Cumulus Linux exists. Cumulus Linux (from Cumulus Networks) is an open source network operating system that can run on a variety of bare metal switches, offering an open source approach to data center networking.

Even better, they offer a free version of their software that will run on the hypervisor of your choice for test and evaluation purposes called Cumulus VX. The examples in this part of this chapter are based on Cumulus VX version 3.7.3.