The nirvana of a data network infrastructure is something akin to light bulbs: When you want light, you switch it on. When you don’t need it anymore, you switch it off. If you go into a different room, you switch on the light in that room then turn it off when you leave. Or, if you want light but not too bright, you can dim the bulb. And of course, you only pay for the power you use while the lights are on.

Similarly, in the world of data networks, firms want to be able to switch services and