The OSI Deprogrammer

It really opened up a whole world of understanding for me when I decided to go look up "RFC 1" to see what it was about.

Reading that — and the few low-numbered RFCs after it — made me realize that "the birth of the Internet" as we know it, was essentially the moment of the deployment of the first network switch (the BB&N IMP), isolating physical networks' electrical properties and collision domains from one-another and using DSPs to arbitrarily re-write packets between different signalling standards — thus rendering uniformity of physical/electrical media and LAN signalling standards, completely irrelevant.

Until that moment, I had always thought of "the Internet" as a standard for LAN networking that grew like a social network until it overtook the world — where things like "Ethernet" and "TCP/IP" were the "Internet flavor" (DARPA flavor?) of those LAN-networking technologies; where "the Internet" was competing with other LAN technology suites, the likes of ChaosNet or AppleTalk or NetBEUI; where people gradually "switched over" from using whatever networking equipment and signalling protocols they had been using, to using Internet networking equipment and standards; and where the fact that people were finally settling on the same networking protocols across multiple Autonomous Systems, allowed them to finally yolk those systems together into inter-networks, with more and more of that happening until we had one big hierarchical LAN called The Internet.

But no! The whole clever thing about "The Internet" is that it didn't do that! It just took all the random proprietary networks that people had built, and connected them together as black boxes, by coming up with a set of standards for how the networks would speak to one-another at their border gateways, and leaving everything else up to implementation, with the assumption of border-gateway routers being implemented by each LAN-technology-vendor to translate between "Internet" signalling and whatever that LAN was doing!

And, in that view, the whole "layer separation" concept — of there being such a thing as an "IP packet" that bubbles up to userland separately from any delivery enveloping — wasn't fundamental to The Internet; in fact, existing protocols that were vertically integrated continued to work, being rewritten into something else when they reached the AS border gateway. The "layer separation" was an optimization to allow new "post-Internet" protocols to be passed "transparently" across AS border gateways without those gateways needing to know about them to rewrite them.

Rather, these "post-Internet" protocols, consisting of separate "LAN envelope" and "Internet payload" parts — and designed with trancieving logic on the endpoints such that the "Internet payload" could traverse the [lossy, laggy] Internet intact — could simply be re-enveloped from "LAN packets" into "Internet packets." And the responsibility for constructing/parsing the "LAN envelope" part would be taken away from userland, made the responsibility of the OS, so that "post-Internet" applications could be portable between computers that used different LAN technologies but wanted to speak the same Internet protocols.

But, of course, network stacks continued to support non-layer-separated communication for decades afterward the advent of The Internet; and AS border gateways continued to support rewriting these protocols "at the edge" for just as long.

It wasn't until much later that LAN networking equipment truly became commoditized. (I have a Windows 2000 manual that describes its support for token-ring networking. Windows 2000!) In a fully post-Internet era, when everyone is using Internet protocols, a "network" could no longer offer much to differentiate itself. So we started to see shifts to actually standardize on LAN technologies, with vendors all moving toward making the same stuff. At that point, border gateways began getting simpler, and companies like Cisco that had made their fortune in the AS-border-gateway space stopped being household names, instead being relegated to the NOC (as they had successfully pivoted into dumb-but-high-throughput enterprise LAN switching, and even-dumber-but-even-higher-throughput Internet backbone switching.)

Other things use Ethernet. Routers, when connected to each other, often use a local Ethernet network to communicate.

Think of the TCP/IP Internet as it's own network, ignoring how routers physically talk to each other. Sometimes it's a directly link, a wire. Sometimes it's carrier pigeons. Sometimes it's WiFi. Sometimes it's Ethernet. Whatever it is, it's local to between the routers and does not extend outside that.