Comment by pjc50
2 days ago
> Ethernet had to adapt to deterministic real-time needs
Without being able to get too into the telco detail, I think the lesson was that hard realtime is both much harder to achieve and not actually needed. People will happily chat over nondeterministic Zoom and Discord.
It's both psychological and slightly paradoxical. Once you let go of saying "the system MUST GUARANTEE this property", you get a much cheaper, better, more versatile and higher bandwidth system that ends up meeting the property anyway.
> not actually needed
What you need is more that enough bandwidth.
Think of the difference between a highway with few cars versus a highway filled to the brim with cars. In the latter case traffic slows to a crawl even for ambulances.
It seems like it was just cheaper and easier to build more bandwidth than it was to add traffic priority handling to internet connectivity.
And that cheaper bit I think just came from reduced complexity. With things like ATM circuits and other similar highly reliable and predictable methods, they needed a lot of hand holding. You needed to provision an ATM circuit, you needed to make sure across the network that the path was there, capable, maintained, and configured, and you had visibility end to end
That was a selling point, because "hey we guarantee this circuit" but it was also very expensive and labor intensive
Where just dumping your bits into the internet and letting the network figure it out outsourced a lot of that complexity to every hop along the network you didn't own. But, because they care about their networks everyone would (in theory) make sure each hop was healthy, so you didn't need to hand hold your circuit or route completely end to end
I saw a story once, which may well be completely made up, about why AT&T got out of the cell phone business. They had a research project, but reliability was an issue. They couldn't see a way to do better than 1 dropped call in 10,000. Their standard for POTS at the time was 1 in 2 billion.
Seeing that the tech would never be good enough, they sold off the whole thing for cheap. Years later, they bought it back for way, way more money because they desperately needed to get into the cell phone business that was clearly headed to the moon.
I totally understand the pride they had in the reliability of their system, but it turns out that dropped calls just aren't that big of a deal when you can quickly redial and reconnect.
Seems a little sus. AT&T basically created the cellular mobile phone, and built up an analog, then digital system (D-AMPS/TDMA). AT&T sort of sold out the mobile business in 2004 to Cingular (BellSouth) because TDMA was a dead end. They then bought BellSouth back in 2006 and carried on with CDMA.
Those old phones had a long range. It was hard to make small ones because the old AT&T towers were much farther apart, up to 40km. Meanwhile, their competitors focused on smaller coverage areas (e.g. 2km or less for PCS) and better tech (CDMA), and it seemed to pay off.
This is a minor detail, but the "AT&T" that bought BellSouth in 2006 was the AT&T formerly known as SBC which bought the husk of Ma Bell and rebranded itself, i.e. the AT&T we have today.
Yeah, big differences between an absolute guarantee and "we'll take as much as we can get"
> People will happily chat over nondeterministic Zoom and Discord.
Well, not "happily". (Doesn't every video conference do the "hold on, can you hear me? I have wifi issues" dance every other day?) But it works on a good day.
At work it became mostly flawless. Everybody is used to it and people can jump in calls quickly when chat discussion etc don't suffice. The glitches are on a comparable level to physical meetings where somebody comes late and disturbs all while getting settled or somebody speaking too quiet for the room.
In my club when there is a virtual club meeting however, where people don't have frequent video meetings there is always somebody with trouble ... often the same.