The truth is, however, that while protocol designers may talk about these things, and network designers study them, very few networks today are built using any of these models. What is often used instead is what might be called the Infinitely Layered Functional Indirection (ILFI) model of network engineering. In this model, nothing is solved at a particular layer of the network if it can be moved to another layer, whether successfully or not.
There are many times in networking history, and in the day-to-day operation of a network, when an engineer has been asked to do what seems to be impossible. Maybe installing a circuit faster than a speeding bullet or flying over tall buildings to make it to a remote site faster than any known form of conveyance short of a transporter beam (which, contrary to what you might see in the movies, has not yet been invented).
sarcasm warning—take the following post with a large grain of salt
A thousand years from now, when someone is writing the history of computer networks, one thing they should notice is how we tend to reduce our language so as many terms as possible have precisely the same meaning. They might attribute this to marketing, or the hype cycle, but whatever the cause this is clearly a trend in the networking world. Some examples might be helpful, so … forthwith, the reduced terminology of the networking world.
Software Defined Networking (SDN): Used to mean a standardized set of interfaces that enabled open access to the forwarding hardware. Came to mean some form of control plane centralization over time. Now means automated configuration and management of network devices, centralized control planes, traffic engineering, and just about everything else.
Fabric: Used to mean a regular, non-planar, repeating network topology with scale-out characteristics. Now means any vaguely hierarchical topology that is not a ring.