I still remember a nightmare a few years ago when we had to change our network configuration to grow our servers, and development came to a screeching halt for a few days as we had to shut down service to re-route cables, physically move network equipment, and reconfigure everything.

That's when a friend of mine who works for a cloud provider told me, "We manage our networks in code, too," and that we could change even complex network topologies on the fly by changing a few lines of configuration files.

I was skeptical at first, but network virtualization really opened up a whole new world for me, allowing me to design and manage my network software, freeing me from physical constraints.