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USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

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Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#11

Post by wlesieutre »

walterbell wrote: post #2

Will it be possible to connect a Thunderbolt 3 Macbook or Intel Ice Lake PC via USB-C cable to a USB 4.0 device and obtain 40Gbps throughput?

Article says "The USB4 specification will be based on the Thunderbolt protocol that Intel has contributed to the USB Promoter Group. The new interface will use USB Type-C connectors and will maintain backwards compatibility with USB 2.0, USB 3.2, and Thunderbolt 3 interfaces", so bet on probably. But maybe not, they might only mean that a USB4 computer can use a TB3 device.

I expect they'll continue the trend of inscrutable capability differences in USB-C ports, cables, and devices. To get the USB4 40GBps mode (effectively TB3) it's still going to be a more expensive active Thunderbolt-style cable, not a vanilla USB cable. Which means that standard markings for those cables will (hopefully?) be part of the USB4 spec.

Unfortunately, knowing USB-IF the major change from the TB3 to USB4 spec will be to drop the current Thunderbolt symbol on the ports and cables and replace it with a new variation of USB-super-hyper-mega-speed symbol to make cables as confusing as possible.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#12

Post by MichailP »

MichailP wrote: post #9

Does this also mean that soon every computer will be making noise/radiating waves around 40GHz? Can someone with more depth in this area shine some light on this?

One more question. Does this also mean that soon every computer will become software defined radio up to 40GHz?

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#13

Post by randyrand »

davnicwil wrote: post #6

As someone who knows next to nothing about how USB actually works and just uses it, what goes into making each USB generation faster? At the physical layer, is it the materials in the cables are getting better? Or new ways of using the same materials? At the protocol layer, is it newly developed computer science theory being applied or is it just old fashioned pragmatic engineering iteration, looking at usage and mak…

Nope. Much simpler. Just enabling the use of the other data lanes that were already in the cable waiting to be used one day.

USB-C has 4 differential twisted pair data lines.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#14

Post by jsgo »

penagwin wrote: post #8

Here's an idea, let's make different connector shapes depending on the cable/connector's capabilities, lets do one for connectors that support display, one for power, one for thunderbolt, that way they're easy for the average consumer to identify! Oh wait that's the issue USB was supposed to solve in the first place....

My hope is that Type-C is going to be all of those things so that in the future, I only need one kind of cable (until the inevitable new plug that supplants it, but hopefully universally used as well). Currently, I have to pay attention to a USB3 Type-C cable vs a Thunderbolt 3 cable as there is a difference (I was shopping for a long TB3 cable and was unable to find one. Instead, seems the longer ones tend to be USB3 Type-C cables).

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#15

Post by klodolph »

walterbell wrote: post #2

Will it be possible to connect a Thunderbolt 3 Macbook or Intel Ice Lake PC via USB-C cable to a USB 4.0 device and obtain 40Gbps throughput?

Probably depends on the specs of the cable, and other factors like which port you plug into, cable length, etc.

Some people are complaining about how this doesn't match expectations, which are that you get the same speed just by using the right shape of cable (and don't care about cable specs). I think that the reality is that this is really pushing the envelope, and 40 Gbit/s isn't that far from typical memory bandwidth (order of magnitude). There are only so many lanes of PCIe to go around, and you're going to end up with some ports getting more than others. We already have problems in Ethernet land with the different cat 5e / cat 6 / cat 7 cables, where bandwidth autonegotiation is mandatory. Most people just want it to work, and if you want your full bandwidth you have to pay attention to the exact specs of every device in the signal path because you can't be sloppy the way you could with 100BASE-T or even 1000BASE-T.

That's a bit of a rant, but I just think that some of the problems with user experience in this area are just down to the fact that this really is a lot of bandwidth to try and push through an external cable, and you end up with the simultaneous goals of having high bandwidth, lots of ports, having all ports be the same, and not charging an arm and a leg for a laptop. Sacrificing bandwidth on a couple ports makes sense to me, in this context.

Seems like the user experience pays, cause I'm not sure how I'm supposed to know which ports have bandwidth.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#17

Post by wlesieutre »

penagwin wrote: post #10
wlesieutre wrote: post #7

Earlier quoted context omitted.

It ought to be USB 3.3 Gen 2x2x2, and USB 3.2 Gen 2x2 will be retroactively updated to USB 3.3 Gen 2x2 because everything is always the newest version of USB.

Best part is all USB 3 ports get to be rebranded as USB 3.3 as well.

I'm honestly surprised that they haven't rebranded USB 2 into USB 3.2 Gen 0 and USB 1 into USB 3.2 Gen -1.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#18

Post by pkaye »

davnicwil wrote: post #6

As someone who knows next to nothing about how USB actually works and just uses it, what goes into making each USB generation faster? At the physical layer, is it the materials in the cables are getting better? Or new ways of using the same materials? At the protocol layer, is it newly developed computer science theory being applied or is it just old fashioned pragmatic engineering iteration, looking at usage and mak…

I'm no means an expert but up to USB 2.0 there were 4 pins (2 for power and 2 differential signals for bidirectional data) With USB 3.0 they added 4 more signals for separate transmit/receive. Initially they used 8b/10b encoding and then switched to 128b/132b encoding. They also increased the signaling rate with each generation. Also in the USB 2.0 and earlier the higher level protocols were kind of inefficient with lots of back and forth. So they improved upon that. And I'm sure they also tightened up on the cable and connection specs to increase the signaling rates. So a lot of little improvements added up.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#19

Post by jsgo »

wlesieutre wrote: post #11
walterbell wrote: post #2

Will it be possible to connect a Thunderbolt 3 Macbook or Intel Ice Lake PC via USB-C cable to a USB 4.0 device and obtain 40Gbps throughput?

Article says "The USB4 specification will be based on the Thunderbolt protocol that Intel has contributed to the USB Promoter Group. The new interface will use USB Type-C connectors and will maintain backwards compatibility with USB 2.0, USB 3.2, and Thunderbolt 3 interfaces ", so bet on probably . But maybe not, they might only mean that a USB4 computer can use a TB3 device. I expect they'll continue the trend of in…

or port color. We've used blue and red at least, guess it is time for green (in which case, confusion for the Razer Blade users).
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