You Can Always Add Another Layer of Indirection (RFC1925, Rule 6a)
Many within the network engineering community have heard of the OSI seven-layer model, and some may have heard of the Recursive Internet Architecture (RINA) model. 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.
For instance, Ethernet is the physical and data link layer of choice over almost all types of physical medium, including optical and copper. No new type of physical transport layer (other than wireless) can succeed unless if can be described as “Ethernet” in some regard or another, much like almost no new networking software can success unless it has a Command Line Interface (CLI) similar to the one a particular vendor developed some twenty years ago. It’s not that these things are necessarily better, but they are well-known.
Ethernet, however, goes far beyond providing physical layer connectivity. Because many applications rely Continue reading
