How did Ethernet go from fat cables and vampire taps to RJ35? Is it still exactly the same protocol (is that even the right word?) as it was back then?
> How did Ethernet go from fat cables and vampire taps to RJ35?
Layers. The physical signaling is vastly different but the content that rides on it can remain the same. If you study the OSI model (https://en.wikipedia.org/wiki/OSI_model) you will know more about it than me.
I don't know how faithfully modern (or ancient) Ethernet follows this model - it might predate this work. Some layers might be blended for the sake of efficiency, but there are definitely layers.
There are a lot of L1 layers that have been used under Ethernet. There were several revisions of the coaxial cable used for ethernet before we switched to the rj45 terminated twisted copper cable everyone thinks of when you say "ethernet". Again, there are several iterations for the twisted copper physical layer.
More recently, we also run ethernet over optical fibers. The varience within the fiber family of cables is probably greater than the variance in either copper or coax.
At 10mbps half duplex, the protocol is nearly the same. Just twisted pair uses differential pair signalling and and coax uses a shared ground and high or low on the center conductor relative to the shield (IIRC). And twisted pair relies on a hub to create a bus. From there you go to 10M/full duplex where the rx and tx pairs are fully separated so collision detection can be disabled.
100base-tx increased the symbol rate, added speed and duplex negotiation (layered into the existing link pulse signaling), but otherwise kept things the same; you can even run a 100base-tx hub.
1000Base-T is a wide departure at the signalling level; all 4 pairs are used simultaneously, bidirectionally, the symbol rate is the same as 100base-tx, but each symbol carries more bits. But the ethernet frames are pretty much the same. (Larger frames started appearing around the same time as gigE, as I recall, but that might not be accurate)
> How did Ethernet go from fat cables and vampire taps to RJ35?
At least, at university: students like me that got hired cheaply and rewired everything. :)
That was not a fun summer, but I learned a lot.
> Is it still exactly the same protocol (is that even the right word?) as it was back then?
I would be surprised, given that coax is equivalent to 3 conductors, and catX cables have 8. And that's before we get into fibre. I would expect they have sime high-level protocol (frames etc.) that gets mapped onto the physical signaling, but I don't know much about that (resource suggestions welcome!).
I do know that going from a broadcast medium to switched point-to-point is a lot more efficient etc.
Plus the taps were notoriously unreliable (variable connection quality). And would cause reflections in the cable as well, which is fun.
Yes it is the same protocol. (Minor revisions change details, jumbo frames etc)
The cables form the physical connection, on that Ethernet defines a way to determine who may send a message (essentially anybody can send while quiet, and if a conflict is detected everybody retries after a random time)
The big thing which changed is that we are often using switched networks, instead of all nodes attaching to the same cable, but that's a change in a higher layer.
Ethernet Designers where smart not tontine the spec to properties of a specific material for transport, but abstract ether where signals travel.
Every once in awhile you'll hear the odd story about someone tracking down a bottleneck in their network and finding an old 10 or 100mbps ethernet link somewhere. I doubt it happens much anymore, but your 10 gigabit gear should still be able to talk to your 10 megabit gear no problem, which I do find impressive.
I've done it deliberately. I had to test a cellular device from somewhere in Asia, but I'm in the US. The Asian provider had sent us a femtocell with developer's firmware that bypassed the GPS check at startup, which would create a little bubble of their coverage in our RF test chamber, and we could put the DUT in the same chamber and do the testing.
Trouble is, the femtocell wanted a network connection, and our RF chamber didn't have an RJ45 passthrough. Some emails got sent, the chamber vendor could sell us a new passthrough module but it was on backorder, ETA two months or something.
So the following evening, I swung by the e-waste recycler where I used to volunteer years prior, which meant I could just give the proprietor a wave and then let myself into the back room and pick the pile. And sure enough, I found a couple of 8-port 10base-T ethernet hubs, with 10base-2 connections on the back for connection to a coax segment. I talked him up to twenty bucks so I'd have an expense to submit; the company did not deserve to get this for free.
Back in the RF lab the following day, it was a trivial matter to convert the BNC connector on the hubs to the N connector in the chamber wall, locate one of the hubs inside the chamber, and connect the femtocell to it. The one outside got the internet connection, which had been running at gigabit speeds but now found itself negotiating at 10/half! (I wonder if the campus networking folks get alerts when that happens. Because it's almost surely not what's intended, unless I'm around.)
The younger techs in the lab mere MYSTIFIED at this exotic hardware that could send Ethernet signals over coaxial cable! That must be expensive! How did you come up with it so fast! Whoever made that must've had this application in mind, but what a niche application! Amazing!
I really need to dive deeper into networking…