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Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

jeffgeerling.com

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Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#11

Post by robin_reala »

nutjob2 wrote: post #9

Somewhat off-topic: has anyone implemented USB C based networking? So for instance you have two or more machines that have USB 4 ports at 20 to 80 Gbps and you plug in the appropriate USB C cables to connect them. What do you need to make the connections appear as a (point to point) part of a regular TCP/IP network? Seems much cheaper than Ethernet if you already have the ports.

USB-4 is basically Thunderbolt right? Thunderbolt networking is pretty automatic on Macs at least: https://support.apple.com/en-gb/guide/mac-help/mchld53dd2f5/...

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#12

Post by imoverclocked »

nutjob2 wrote: post #9

Somewhat off-topic: has anyone implemented USB C based networking? So for instance you have two or more machines that have USB 4 ports at 20 to 80 Gbps and you plug in the appropriate USB C cables to connect them. What do you need to make the connections appear as a (point to point) part of a regular TCP/IP network? Seems much cheaper than Ethernet if you already have the ports.

Yup, totally doable. Of course, it’s a point to point link so if you want to build a whole cluster that way then you’ll need a lot of usb-c ports or you’ll need to make more of a mesh topology.

I believe MacOS supports it via the usual network control panel. I’ve used it for transferring data from an older laptop to a newer one. The cable is more expensive than fiber, last time I checked.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#13

Post by m463 »

AnthonBerg wrote: post #7
teaearlgraycold wrote: post #3

It’s crazy that the Ethernet chips consume more power (presumably - because of the heat) than the processor in the computer. How is driving 25Gb/s such a hot task compared to driving multiple 40Gb/s Thunderbolt ports?

As I understand it, it takes a bit of anger to get electromagnetism to wiggle that fast over copper. Imperfect transistors using their full operational envelope to control a sort of chaotic thing? Fields and stuff.

can confirm. anger causes loud fast communication that can be heard over background noise. I've heard anger using light-based signalling like sign language might be more efficient.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#14

Post by QuantumNomad_ »

SlavikCA wrote: post #10

What are typical use cases for needing 25Gbps? Author talks about 4k video, but AI tells me that for "4K production mastering (ProRes 422 HQ, 4:2:2, 10-bit)" the rate is under 2Gbps. I'm not saying it's not needed, - just curious.

What if it’s uncompressed footage at 60fps? And dealing with many shots. And on top of that maybe working with multiple projects in parallel.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#15

Post by teaearlgraycold »

AnthonBerg wrote: post #7
teaearlgraycold wrote: post #3

It’s crazy that the Ethernet chips consume more power (presumably - because of the heat) than the processor in the computer. How is driving 25Gb/s such a hot task compared to driving multiple 40Gb/s Thunderbolt ports?

As I understand it, it takes a bit of anger to get electromagnetism to wiggle that fast over copper. Imperfect transistors using their full operational envelope to control a sort of chaotic thing? Fields and stuff.

They get hot using fiber as well.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#16

Post by dlcarrier »

areoform wrote: post #4
pzmarzly wrote: post #2

One of the YouTube comments pointed out the issue is most likely the lack of support for SMB Direct (RDMA) in macOS. Would be nice to repeat the test on a Windows/Linux laptop.

https://developer.apple.com/documentation/technotes/tn3205-l... MacOS has supported RDMA over thunderbolt since March 19th.

Is RDMA something worth looking into for connecting two random Linux computers? I've been extremely underwhelmed by the stability and performance of my NFS shares.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#17

Post by warpflyght »

nutjob2 wrote: post #9

Somewhat off-topic: has anyone implemented USB C based networking? So for instance you have two or more machines that have USB 4 ports at 20 to 80 Gbps and you plug in the appropriate USB C cables to connect them. What do you need to make the connections appear as a (point to point) part of a regular TCP/IP network? Seems much cheaper than Ethernet if you already have the ports.

Yes, there are a few standard(ish) mechanisms for doing this, like [RNDIS][1] and NCM. If you have two Thunderbolt-equipped Macs and connect their ports together, you can use Bonjour/zeroconf for network discovery between them.

[1]: https://en.wikipedia.org/wiki/RNDIS

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#18

Post by andy99 »

SlavikCA wrote: post #10

What are typical use cases for needing 25Gbps? Author talks about 4k video, but AI tells me that for "4K production mastering (ProRes 422 HQ, 4:2:2, 10-bit)" the rate is under 2Gbps. I'm not saying it's not needed, - just curious.

Running local LLMs split across machines. Pretty sure the author has some other posts about doing that.

Edit: https://www.jeffgeerling.com/blog/2025/15-tb-vram-on-mac-stu...

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#19

Post by QuantumNomad_ »

imoverclocked wrote: post #12
nutjob2 wrote: post #9

Somewhat off-topic: has anyone implemented USB C based networking? So for instance you have two or more machines that have USB 4 ports at 20 to 80 Gbps and you plug in the appropriate USB C cables to connect them. What do you need to make the connections appear as a (point to point) part of a regular TCP/IP network? Seems much cheaper than Ethernet if you already have the ports.

Yup, totally doable. Of course, it’s a point to point link so if you want to build a whole cluster that way then you’ll need a lot of usb-c ports or you’ll need to make more of a mesh topology. I believe MacOS supports it via the usual network control panel. I’ve used it for transferring data from an older laptop to a newer one. The cable is more expensive than fiber, last time I checked.

I have also used a USB 4 cable to network two MacBook Pros to one another and can confirm that it was very simple to connect and it was fast as heck. The USB 4 cable I used was rated for up to 40 Gbps.
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