[musicale]

The telephone people were basically right with their criticisms of TCP/IP such as:

What about QoS? Jitter, bandwidth, latency, fairness guarantees? What about queuing delay? What about multiplexing and tunneling? Traffic shaping and engineering? What about long-haul performance? Easy integration with optical circuit networks? etc. ATM addressed these issues, but TCP/IP did not.

All of these things showed up again once you tried to do VOIP and video conferencing, and in core ISPs as well as access networks, and they weren't (and in many cases still aren't) easy to solve.

[bobmcnamara]

Outside of VOIP & live video, most applications today don't have such tight requirements for QoS/Jitter/Latency/QueueingDelay/..., but oh man back then the top applications were all either telephone calls or signals run over telephone lines.

[cachius]

How could a circuit switched network look like at today’s scale?

[bobmcnamara]

Joke: TCP, but you RST the connection whenever a packet drops.

[musicale]

The optical layer is still circuit-switched.

Also MPLS is basically a virtual circuit network.

[hollerith]

If that is true, then why did the telcos rapidly move the entire backbone of the telephone network to IP in the 1990s?

And why are they trying to persuade regulators to let them get rid of the remaining (peripheral) part of the old circuit-switched network, i.e., to phase out old-school telephone hardware, requiring all customers to have IP phone hardware?

[musicale]

They moved to IP because it was improving faster in speed and commoditization vs. ATM. But in order to make it work, they had to figure out how to make QoS work on IP networks, which wasn't easy. It still isn't easy (see: crappy zoom calls.)

Modern circuit switched networks use optics rather than the legacy copper circuits which date back to telegraphy.

[mulmen]

You can criticize something and still select it as the best option. I do this daily with Apple. If you can’t find a flaw in a technical solution you probably aren’t looking close enough.

[kragen]

Packet switching is cheaper; even though it can't make any guarantees about latency and bandwidth the way circuit switching could, it uses scarce long-haul bandwidth more efficiently. I regularly see people falling off video calls, like, multiple times a week. So, in some ways, it's a worse product, but costs much less.