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View Poll Results: How much bandwidth do allocate for DisplayLink in your system?
10 Gbit/s 1 100.00%
5 Gbit/s 0 0%
Don't know / doesn't seem to matter 0 0%
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Old 10-20-2021, 12:08 PM   #1
jupiterbee
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Default 10 vs 5 Gbit/s connection: how much of a compromise?

Just joined the forum. I've been a DisplayLink user for a year, and been happy with it. I was wondering, how much of a real-world difference does it make, if I connect the dock to a 5 Gbit/s or a 10 Gbit/s USB-C port?

I've got a TB3 monitor which offers 5 Gbit/s USB-C ports. DisplayLink works fine on those. Alternatively, I could connect the dock directly to the Mac, giving it 10 Gbit/s. But then I have to connect two cables instead of one when docking and undocking. Fewer would be better.

1. What kind of differences, and under what conditions, should I expect between these two choices? Obviously "more bandwidth is better" in a general sense. But frankly, I don't see much of a difference. But are there specific example scenarios and workloads in which it starts to matter?

2. What kind of Gbit/s bandwidth does two 1080p 60 Hz monitors require from the video signal alone? What about 2x 4k at 60 Hz? I'm wondering how much is then left for Ethernet and possibly a USB drive attached to the dock.

3. What are the symptoms of the bandwidth getting saturated? Does DisplayLink lose frames, or quality, or both, when it has to work around degraded conditions?

Overall, I'm wondering, what it actually is that moves in that cable. I bet it's not a regular video signal, otherwise why have a DisplayLink chip inside the dock. What kind of wizardy does the chip actually do, if you don't mind me asking?

All that said, I'm constantly surprised how well this solution works. Using a Lenovo dock from 2018-2019.

Last edited by jupiterbee; 10-20-2021 at 12:10 PM.
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Old 10-21-2021, 02:10 PM   #2
AlbanRampon
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Hello and welcome,

Dual 4Kp60 + Ethernet fits comfortably in 5Gbps and there is no benefit in connecting this DisplayLink chip to a 10G input. We fit 1080p60 on USB2 with an older codec...

The only reason I would see for 10Gbps is if you were extensively using external Flash or hard drives, but I am not convinced the docking station you are using has 10G USB hubs inside, you'd need to check with the manufacturer. If it has 5G hubs, then connecting to a 10/20G port won't change a thing.
Our algorithm is adaptive on computing and link bandwidth as well as content type. Like a famous soda brand, our recipe is trade secret.
Unlike a DP/TB link which always sends all the display content 60 times per second, we optimise the content sent to the dock and we create the full bandwidth video signal in the dock, also allowing us to get the best interoperability. We don't tend to lose frames, but when we sense bandwidth is tight, we can adapt our encoding to keep low latency.

In that cable, DisplayLink moves real, standard, USB packets. That is why you can daisy-chain the devices to extend your setup.
DisplayLink is media agnostic, so USB isn't the only way: HTC Vive wireless VR headset relies on DisplayLink technology, where both low latency and high quality graphics are critically important.
Kind regards,
Alban
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Old 10-23-2021, 12:27 PM   #3
jupiterbee
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Thank you for a comprehensive answer. This then explains, why I'm not seeing much of a difference (beyond placebo perhaps) between having the dock directly attached to a MacBook Air M1 at 10 Gbit/s, versus daisy-chaining it behind a TB3 display with an integrated 5 Gbit/s USB-C hub.

Knowing this, I might revert back to the daisy-chained configuration. There's beauty in connecting a whole orchestra of devices with one cable. A few months ago I had doubts, whether that would work, but in practice it has worked very well.

There are no bandwidth-intensive drives attached at the moment. But it worked fine even when I had a spinning USB3 disk and a Samsung T5 attached. I think of it a bit like a flight of a bumblebee: it should't be able to fly, it's too much, yet it does.

I checked out the new MacBook Pros with multi-display capabilities, but knowing what I know now about using DisplayLink, and getting the power out of M1 that I do ... there's just no compelling reason to get a new Mac, especially when my main usage scenario is multiple displays connected to a clamshell laptop.

A new 30+ inch iMac with M1 Max might make me upgrade though, especially if it's mini-led at 120 Hz. Until then, DisplayLink it is. Thanks again for the answer.

A quick follow-up though: is there a way to make 120 or 144 Hz work via DisplayLink, using conservative resolutions? If I my side-wing DisplayLink-attached monitors would natively support 100+ Hz, would I actually get that refresh rate to work using an M1 Air and ThinkPad Hybrid USB-C with USB-A Dock?

Last edited by jupiterbee; 10-23-2021 at 12:32 PM.
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