Why is OpenFlow so advantageous to a company like Google? In the traditional model you can think of routers as akin to taxicabs getting passengers from one place to another. If a street is blocked, the taxi driver takes another route — but the detour may be time-consuming. If the weather is lousy, the taxi driver has to go slower. In short, the taxi driver will get you there, but you don’t want to bet the house on your exact arrival time.
With the software-defined network Google has implemented, the taxi situation no longer resembles the decentralized model of drivers making their own decisions. Instead you have a system like the one envisioned when all cars are autonomous, and can report their whereabouts and plans to some central repository which also knows of weather conditions and aggregate traffic information. Such a system doesn’t need independent taxi drivers, because the system knows where the quickest routes are and what streets are blocked, and can set an ideal route from the outset. The system knows all the conditions and can institute a more sophisticated set of rules that determines how the taxis proceed, and even figure whether some taxis should stay in their garages while fire trucks pass.
Therefore, operators can slate trips with confidence that everyone will get to their destinations in the shortest times, and precisely on schedule.
