
USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB - BogdanPetre
https://www.anandtech.com/show/14048/usb4-specification-40-gbps-type-c-tb3
======
WhitneyLand
What's optional?

That's the most important thing to know is what's optional in the spec.

That could make it great or a major pain. I'm referring to how many features
the specification defines as "optional" for manufactures and that the USB
organization requires for logos.

This is why even USB-C is a nightmare. Consider a USB-C cable or device port.
It could be charge only, data only, monitor support. There are even more
permutations and sub-features. Oh, you wanted charging and found one that has
it? Know how much power it enough or overkill? It could provide 15 watts, 100
watt, etc. Think you'll just google the specs page? Sure, they never miss
providing any of these details or make any mistakes.

Whether USB4 means one thing with nothing optional (or at least a very small
number of combinations), will probably determine how much you like it or get
annoyed by it.

HP even made it worse with a laptop USB-C port that could technically be used
for certain docking functionality but tried to fud-deny allowing it for
marketing reasons.

~~~
majewsky
Market opportunity: A USB-stick-shaped device that, when you plug it into a
USB-C port, probes the port and lights up LEDs to show the port's
capabilities.

    
    
      [x] 5 Gbps
      [x] 10 Gbps
      [ ] 20 Gbps
    
      [ ] Power Delivery
    
      [x] DisplayPort Alternate Mode
    

And so on.

~~~
mnx
Yeah until the spec changes/expands and you now need another device to tell
you whether that stick is up-to-date on the spec :D

~~~
Yetanfou
As long as the actual port remains identical the widget could be made up to
date with a software upgrade.

~~~
raducu
You cannot add a led with a software update :)

~~~
egwynn
Not with _that_ attitude you can’t!

------
sp332
Ars Technica just wrote an article about the confusing names of USB versions
[https://arstechnica.com/gadgets/2019/02/usb-3-2-is-going-
to-...](https://arstechnica.com/gadgets/2019/02/usb-3-2-is-going-to-make-the-
current-usb-branding-even-worse/) and now they have another one about this
name.
[https://arstechnica.com/gadgets/2019/03/thunderbolt-3-become...](https://arstechnica.com/gadgets/2019/03/thunderbolt-3-becomes-
usb4-as-intels-interconnect-goes-royalty-free)

~~~
izacus
I feel like hand-wringing around that is a bit overexaggerated - at the end of
the day the differences really matter for only really tiny subset of devices
that need those 10GBit+ transfers and in that case you can guide yourself by
the "SuperSpeed 10Gbit" "Superspeed 20Gbit" logos on the actual box.

For everything else the protocols are forward and backward compatible, so you
just plug in the cable and it works.

~~~
gambiting
So remind me, why can you walk into any apple store, pick up a new MacBook and
a 5K LG monitor, and when you plug in the monitor using the USB-C cable that
was bundled with the MacBook it just won't work at all?

My point is - the standards might be back and forward compatible. But the
cables and ports definitely aren't - and your average consumer has absolutely
no way of knowing. They look absolutely identical on the outside and when they
don't work it's for completely non-obvious reasons.

~~~
abrowne
A lot (most?) charge cables are USB 2.0 — just enough data to negotiate the
higher power. If they supported faster data too, they'd be more expensive. But
it definitely should be more clear! Apple's minimalism doesn't help in this
case, either.

~~~
stephenr
> Apple's minimalism doesn't help in this case, either.

Apple don't make a "USB-C data" cable - they make a USB-C charge cable, or a
TB3 cable, and the TB3 one _has_ the thunderbolt logo on each end.

They also refer to it specifically as "USB-C Charge Cable", _everywhere_.

~~~
abrowne
Yes, if you buy it standalone. But what about in the computer box? I've opened
a lot of MacBook Pros, and I can't remember seeing any labeling.

~~~
protomyth
I’ve gotten into the habit of taking the supplied cable on all Mac portables
and replacing it with a Thunderbolt 3 40gbs 100w cable from Monoprice before
handing it over to the staff person. It cuts down on “why won’t this work”
questions surrounding monitors and such.

~~~
makomk
Except that longer Thunderbolt 3 cables apparently don't support 10 GBps USB
3.1 speeds. So if you want a cable that actually supports everything, it
probably has to be the _0.5m_ Thunderbolt 3 40gbs 100w cable from Monoprice
(maybe the 1m one too, but the 2m version is an active cable that won't
support USB 3.1)

------
davnicwil
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 making the existing protocols more efficient with tricks and
shortcuts etc?

~~~
randyrand
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.

~~~
artiscode
That sort of explains why USB cables have been getting more expensive. More
copper.

~~~
chris_mc
Probably more like "better tolerances" or something like that. The labor/time
put into a cable is the most pricey part, raw materials are probably only a
few cents, even if you double the copper into it.

------
gumby
> ... it will not be exactly Thunderbolt 3 as its functionality will likely be
> different.

I don't understand how this isn't simply ratifying/renaming current TB3-on-
Type-C-connectors and this cryptic sentence in the page doesn't help. Anybody
know?

This isn't to say that such a renaming might not be a good idea! But it would
be nice to know if my current Type C ports with TB and DB support were in fact
already "USB 4.0."

Also: speaking of nomenclature: notice that according to the press kit slide
show, USB 3.1 Gen 2, USB 3.2 Gen 2x2, and USB4 all have the same "Alternative
Branding": "Super Speed+". Madness!

------
penagwin
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....

~~~
jsgo
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).

~~~
jwr
This is not a realistic expectation, unless you are OK with your "one cable"
being 0.5m long. The "one-cable" thing is a dream, unfortunately.

~~~
CharlesW
"Active Thunderbolt 3 cables support Thunderbolt at 40Gbps data transfer at
lengths of up to 2m. Optical cables are targeted later, with lengths of up to
60m."

[https://blog.startech.com/post/thunderbolt-3-the-
basics/](https://blog.startech.com/post/thunderbolt-3-the-basics/)

~~~
wongarsu
Of course the optical cable won't transfer 100W of power, so we're back to
needing two types of cable (power delivery USB-C and non-power-delivery
USB-C).

I guess technically you could make a USB-C cable that transfers signals
optically and has high-gauge wire for power, but that sounds unwieldly and
expensive.

~~~
nybble41
> Of course the optical cable won't transfer 100W of power

You sure about that? The optical cables will still have copper wires for power
transfer. Only the high-speed data is carried over optical fiber. Eliminating
electrical interference from the data path might even permit higher voltages,
and thus thinner, more flexible wires for the same power.

------
matthewmacleod
So… maybe I'm missing the details, but is this just basically rebranding TB3
as USB4? That would make a lot of sense, if so.

Edit: Ah, I missed "it will not be exactly Thunderbolt 3 as its functionality
will likely be different". That's a clear as mud, then.

------
bits
Whoa. Does the addition of Thunderbolt imply that all USB4 host systems are
exposed to DMA attacks[0]?

Doesn't this open up every USB system (all systems?) to arbitrary,
uncontrolled memory access including silently flashing new firmware/microcode
to system components?

0:
[https://en.wikipedia.org/wiki/DMA_attack](https://en.wikipedia.org/wiki/DMA_attack)

~~~
stephen_g
That's what the IOMMU is for. USB4 being Thunderbolt could therefore be a good
thing, because it will force operating system vendors to actually set that up
correctly, making the hardware more secure generally.

The option also exists to require approving or whitelisting devices before
they are allowed to work over Thunderbolt.

------
chkaloon
Not USB 3.2 Gen 2x2x2?? Come on, consistency people!

~~~
wlesieutre
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.

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

~~~
wlesieutre
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.

~~~
sp332
Would USB 1.1 be USB 3.2 Gen -1.1 or USB 3.2 Gen -0.9? Hmm...

~~~
crooked-v
Neither. It gets to be USB 3.2 Gen -1 Plus.

------
zapzupnz
USB 4? You sure they don't mean USB 3.4 Revision 4 UltraSpeed HyperBus XP for
Workgroups 3.11 Xtreme Edition?

------
cm2187
I'd be curious about 40Gbps for what cable length. TB3 is great, you can in
theory dock a laptop with a single cable that will do charging, 10gbe, USB
hub, etc, but with a max 50cm cable, which makes it quite "un-lappable". I'd
love to do the same with a 2m cable.

~~~
gumby
Copper thunderbolt limit is 3 m. Optical thunderbolt can go much farther
(naturally) but I've never seen it in the wild -- it might even have been
abandoned by now.

~~~
cm2187
But you can't charge a laptop with an optical cable. As for copper, I
understand you don't get 40gbps with a 3m cable (though not a specialist).

~~~
tgsovlerkhgsel
You can, however, charge it with a combined cable that uses copper to bring
power to the laptop (and optical converter), and optics to transfer the data.

~~~
gumby
Good idea, wonder if anyone will ever make one!

------
gigatexal
Royalty free is the huge boon here.

~~~
bubblethink
Intel said that a couple of years ago, and yet you won't find an AMD
laptop/desktop that supports thunderbolt.

~~~
zanny
One, what AMD laptop?

Two, I'd be interested to know if AMD bans board manufacturers from including
TB or if they just don't do it because their heuristics say users don't care
or want it.

I'd imagine now with the rise of USB-C it would be the latter. Before that AMD
was stuck on a 5 year old desktop platform that probably couldn't run
thunderbolt ports even if board makers wanted to include it.

~~~
bubblethink
>Two, I'd be interested to know if AMD bans board manufacturers from including
TB or if they just don't do it because their heuristics say users don't care
or want it

No, AMD boards already include the required TB hardware. They just can't
enable it (yet) for whatever technical or legal reasons. Someone hacked them
to enable it
([https://www.youtube.com/watch?v=uOlQbP63lDQ](https://www.youtube.com/watch?v=uOlQbP63lDQ))

~~~
dogma1138
There is no required hardware needed for Titan Ridge to work other than a PCIe
expansion slot, you need UEFI drivers for it but that's pretty standard for
anything today.

------
artiscode
Honestly, I'm waiting for old USB(USB A, USB B) to be deprecated and USB C
become the new universal USB. As in ATM machine, you get the drill. Current
USB cable situation is a mess - my phone is USB C, but it came with a USB A to
USB C cable. Good thing I can connect it to my 2017 MacbookPro using it's
original USB C charging cable! However then I can't charge. Sometimes I use a
USB C to female USB A dongle to use my phone's USB A male to USB C. And the
whole thing has become expensive, good USB C cables seem to be made out of
gold. Life would become so much easier if everything was USB C to USB C

~~~
jwr
Don't get your hopes up, as this is just a dream. USB-C only specifies the
connector. What your cables support, and what end devices support is anyone's
guess. See for example [https://superuser.com/questions/1199917/what-is-the-d-
shaped...](https://superuser.com/questions/1199917/what-is-the-d-shaped-icon-
next-to-my-usb-c-port/1200112#1200112)

In my opinion, the mess is actually much worse with USB-C, as with earlier
connectors I at least had a chance of guessing whether the cable/connection
will work by looking at the connectors. With USB-C? No idea.

~~~
izacus
In practice this is significantly smaller issue than most media and techies
made out to be.

Most devices are USB, they work and charge over the connector just fine. On
laptops, connecting displays work as well. They will either use TB or
negotiate for HDMI/DP which is also fine.

The only real outliers are crappy companies which deliberately break protocols
like Nintendo on their Switch.

~~~
ksec
>Most devices are USB, they work and charge over the connector just fine.

There are USB-C Charge Cable, that does no Data ( To save cost )

>On laptops, connecting displays work as well. They will either use TB or
negotiate for HDMI/DP which is also fine.

That is assuming the cable could do TB, which is also not true.

Once you get USB-C to everywhere to everyday normal users, they expect it to
plug in and work.

------
MichailP
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?

~~~
781
PCI Express is already working at those data rates.

~~~
gumby
Thunderbolt _is_ PCIe.

~~~
rjeli
Not quite:
[https://twitter.com/whitequark/status/1097777102563074048](https://twitter.com/whitequark/status/1097777102563074048)

"Thunderbolt, uh, does not expose PCIe lanes directly. Thunderbolt is an MPLS-
like packet switching network that can encapsulate PCIe TLPs over a PHY and
MAC without a spec, chips without documentation, and software with barely any
support."

------
koala_man
tl;dr: Intel made Thunderbolt 3 royalty free in 2018, so now it's essentially
being adopted as USB4.

I had to look up what the point of 40Gbps was, and the industry evangelization
site [https://thunderbolttechnology.net/](https://thunderbolttechnology.net/)
explains that it will allow driving one 5k display or two 4k displays, which
is not possible with the 20Gbps offered by USB 3.2 or Thunderbolt 2.

This also helps external GPUs, where TB2/USB3.2 is the equivalent of 2.5 PCI-e
3.0 lanes, while TB3/USB3 is 5.

With that, it seems the goal is to be a viable alternative to PCI-e and HDMI,
rather than just improve on today's USB3 speeds for existing device classes.

~~~
artiscode
Does 40Gbps mean two 4K displays daisy chained?

~~~
lxmcneill
In theory, yes. Since driving one 60hz 4k display at 4:4:4 chroma takes
roughly 18gbps then daisy chaining 2 displays should be possible.

------
walterbell
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?

~~~
wlesieutre
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.

~~~
jsgo
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).

~~~
DaiPlusPlus
Apple will never use coloured ports.

~~~
jsgo
pulling my MacBook Pro out of my backpack to look, it looks like they aren't
fans of iconography to say what a port is capable of either. Can't remember if
my old 2013 MBP had the icons or not, but my current one for sure doesn't.

~~~
wlesieutre
All ports on Apple's laptops behave the same for charging - they'll continue
to provide power while sleeping, but won't _start_ providing power. If you
want to use it as a battery in your backpack while it's closed you have to
plug your phone in, wake the computer up, then put it back to sleep. At least
that was the case last time I tested it.

For the most part they don't need colors because all of the ports are the
same. One recent exception was that the 2016/2017 MBPs had inconsistent
Thunderbolt bandwidth because they didn't have enough PCIe lanes. IIRC left
side had full 40Gbps ports but the right side had 20Gbps. The 2018 version has
full speed on all four.

EDIT - another potential point of confusion, they don't mark Thunderbolt ports
vs USB-C ports. On any given device they're all the same, but they expect you
to know that the 12"-mini-macbook is just USB-C while the Pro and Air are all
Thunderbolt.

So yeah, it'd be helpful to have some symbols on the laptops. They do label
ports on their desktops. I assume this comes down to Ive not wanting labels on
his beautiful chunk of aluminum where someone might accidentally see them
while using it.

~~~
sambroner
Wow, "only starts charging while awake" really explains some confusing
mornings waking up to a dead laptop.

~~~
wlesieutre
To clarify, I'm talking about using the laptop as a power source to charge
other devices (phones, tablets, etc) off your laptop's USB ports.

If you plug them in while the laptop is asleep they won't start charging. If
you plug them in while the laptop is awake they'll start to charge, and
they'll keep going if the computer goes to sleep later.

If you laptop isn't charging itself while plugged in to the wall you have
other problems.

------
alacombe
This is a poisoned gift, there was a twitter conversation posted a couple
weeks ago about the cluterf*ck that thunderbolt is... quite a scary read :-/

[https://twitter.com/whitequark/status/1097777102563074048](https://twitter.com/whitequark/status/1097777102563074048)

~~~
monocasa
Honestly, most of this addresses that, by opening the spec and getting rid of
royalties.

------
aboutruby
Official announcement:
[https://usb.org/sites/default/files/2019-03/USB_PG_USB4_DevU...](https://usb.org/sites/default/files/2019-03/USB_PG_USB4_DevUpdate_Announcement_FINAL_20190226.pdf)

------
modeless
Is it an unpopular opinion that USB is already fast enough and has enough
features and USB implementers should instead work on cost reduction and
compatibility so that we can all move away from USB 2 and pre-type-C
connectors?

~~~
notJim
It's not fast enough. USB cannot drive a 4k monitor at 60hz. You can use the
physical interface to do it, but this uses Thunderbolt. This means that the
dream of a one-cable-for-everything setup is not here yet, unless you use a
Thunderbolt dock, which multiplexes the USB stuff in with the monitor signal.
A thunderbolt dock costs around 10x more than a simple USB dock.

~~~
stordoff
To be honest, I'm not really sure why this is necessary. I don't see why
couldn't have two interfaces - one simple/moderate-speed one for most use
cases, and a fast one (which could incorporate the slower one) for when it's
needed. Trying to cram everything into one interface seems to introduce too
many compromises (I no longer know what the port does) and a lot of
complexity.

~~~
kkarakk
the point is you shouldn't have to know what the port does, it should
seamlessly interconnect. you shouldn't have to be thinking about wires etc.
it's like how bluetooth somewhat seamlessly interconnects across generations
of bluetooth. that's how all standards should be

------
Budabellly
This is quite meaningful for external graphics solutions, PCI peripheral
devices, and other modular pc components.

------
nintendo1889
I am starting to see computers with USB C on the host side. The future of one
single connector to rule them all will be here soon. Wait a minute, we already
had that, it was usb 2.0?!?!

~~~
mac01021
I never saw anyone hooking up a monitor via USB 2.0

~~~
reaperducer
I've seen them for sale on Amazon and elsewhere. I always thought they'd be
neat to throw in a supplemental kit bag for a second display on the go. I
think some of the smaller ones were even bus powered.

~~~
DaiPlusPlus
Those are USB 3.0-based DisplayLink connectors.

Any supposed USB 2.0-based display connectors (I’ve never seen any, I’m just
speculating) would have been some VNC-like contraption involving an emulated
frame buffer on the host.

~~~
vel0city
I've used bus-powered USB 2.0 display adapters in the past, even up to
1920x1080. They're usually a software-based renderer writing to a frame buffer
on the USB device. Big updates or lots of USB traffic meant dropped/torn
frames, and lots of extra CPU power used to drive it. It worked well for word
processing and light web usage, but you wouldn't be watching an HD movie on
it.

------
goalieca
I’d love to ditch HDMI (even on my television!)

~~~
cbg0
To what avail really? You'll just be changing one cable for another. Also,
HDMI 2.1 spec is 48gbps so USB4 wouldn't really be compatible with the latest
HDMI version.

~~~
anticensor
4k TV is 26.52 Gbps at 16:9 aspect ratio, 100fps.

------
snazzycalynx
"The detailed USB4 specification will be published in the middle of 2019 and
half-assed, cheap hardware that only implements a subset of the total features
list in order to cut corners on cost but still use the new name should appear
in 2030 behind flimsy out-of-spec connectors and loose, easily damaged
cables."

I had to add a few things to manage expectations and more accurately reflect
reality, but I think we've got it now.

------
Halluxfboy009
Can it make DP1.4 and HDMI 2.1 obsolete?

~~~
akvadrako
You need one of those to send video, but they could be layered over
Thunderbolt / USB4.

