kohlschuetter

You can also use a BananaPi BPI-R3 for reprogramming. And you can “upgrade“ 10 Gbit/s DACs to 25 Gb/s. Details here https://kohlschuetter.github.io/blog/posts/2026/03/22/unlock...

Many 10GbE DACs can be hacked to run 25GbE, which is something I had to figure out after realizing that it’s not just plug and play as it was with twisted pair cables coming from 1Gb to 2.5Gb…

https://kohlschuetter.github.io/blog/posts/2026/03/22/unlock...

Thank you! I had to stop digging at some point, but honestly I can't wait for someone to port Doom to a ONU.

Thank you! I hope you all have trusted vendors, and no-one gets bent over by the sudden flood of cheap SFP28 cables :-)

I was going from SFP+ to SFP28. Not sure about SFP to SFP28. But with that EEPROM change you could also try going from SFP to SFP+, just use different bandwidth values.

You could also try resoldering new/thicker Twinax wires to old SFP connectors and update the EEPROM. My soldering skills apparently aren't that great. If yours are or you have plenty of old connectors you should give that a try.

Thanks!

AUI: So that's what that port next to the BNC connector on the 3COM 3C509B was for! We've come a long way.

Very timely post!

How does this compare to https://github.com/tianocore/edk2-libc and https://libc.llvm.org/uefi/index.html, for example?

The new low-power Realtek chipsets will definitely push 10 GbE forward because the chipset won't be much more expensive to integrate and run than the 2.5Gbps packages.

It all comes down to performance per Watt, the availability of cheap switching gear, and the actual utility in an office / home environment.

For 10 Gbps, cabling can be an issue. Existing "RJ45"-style Cat 6 cables could still work, but maybe not all of them.

Higher speeds will most likely demand a switch to fiber (for anything longer than a few meters) or Twinax DAC (for inter-device connects). Since Wifi already provides higher speeds, one may be inclined to upgrade just for that (because at some point, Wireless becomes Wired, too).

That change comes with the complexity of running new cabling, fiber splicing, worrying about different connectors (SFP+, SFP28, SFP56, QSFP28, ...), incompatible transceiver certifications, vendor lock-in, etc. Not a problem in the datacenter, but try to explain this to a layman.

Lastly, without a faster pipe to the Internet, what can you do other than NAS and AI? The computers will still get faster chips but most folks won't be able to make use of the bandwidth because they're still stuck on 1Gbps Internet or less.

But that will change. Swiss Init7 has shown that 25GBps Internet at home is not only feasible but also affordable, and China seems to be adding lots of 10G, and fiber in general.

Fun times ahead.

For reference, I'm seeing pings from my Mac to my Linux boxes (Lenovo Tiny5) at well under 1ms, not much worse than between them directly. But yeah, your mileage may vary.

I got me one of these adapters (RTL8127AF TXA403, with SFP+ cage); I haven't properly benchmarked it yet.

There's no driver support on macOS, and for Linux you'd need a bleeding edge kernel. Just trying to physically connect it (along with a connected SFP28 transceiver) to my Mac's Thunderbolt port using an external PCIe-to-TB adapter, macmon tells me a power draw of around 4.3 W, so it's not significantly less for half the bandwidth, but the card doesn't get hot at all.

Be sure to test this adapter on iPad Pro, just for kicks (yes it works!)

Although I managed to panic the kernel a couple of times without the extra heatsinks on...

This 100GbE card is an OCP 2.0 type 2 adapter, which will _probably_ not work with the PX PCB since that NIC has two of these mezzanine connectors, and PX only one.

What also may not work are Dell rNDC cards. They look like they have OCP 2.0 type 1 connectors, but may not quite fit (please correct me if I'm wrong). They do however have a nice cooling solution, which could be retrofitted to one of the OCP 2.0 cards.

I've also ordered a Chelsio T6225-OCP cards out of curiosity. These should fit in the PX adapter but require a 3rd-party driver on macOS (which then supports jumbo frames, etc.)

What also fits physically is a Broadcom BCM957304M3040C, but there are no drivers on macOS, and I couldn't get the firmware updated on Linux either.

Very nice tip, thank you!

I measure around +11W idle. While running a speed test, I read ca. +15W.

Thank you!

I think, tragically, the blog post has caused this price increase.

The offers on Amazon are most likely all drop shippers trying to gauge a price that works for them.

You might have better luck ordering directly from China for a fraction of the price: https://detail.1688.com/offer/836680468489.html

Disconnected as in "network"? What PCIe card do you use? Can you update the firmware (maybe from Windows)?

Also check the BIOS settings (try setting TB security to "No Security" or "User Authorization")

Some OEM Mellanox cards can be cross-flashed to NVIDIA's stock firmware, maybe that's also relevant.

Thanks! Have you tried the boltctl/rescan setup I mentioned in the post? It should get you going, as long as your Thunderbolt/USB4 setup is correct.

If you're using an adapter card to add Thunderbolt functionality, then your mainboard needs to support that, and the card must be connected to a PCIe bus that's wired to the Intel PCH, not to the CPU.

My optical transceiver gets to around 52 °C (measured via IR camera), well below its design limit, so that's not bad.

If truly concerned, one could use SFP28 to SFP28 cage adapters to have the heat outside the case, and slap on some extra heatsinks there.

It also works on iPad Pro :)

The limitation is Thunderbolt (32 Gbps theoretical limit for PCIe 3 tunneling).

My goal was to get a fanless setup (for a quiet office).

If that's not a requirement just get the Raiden Digit Light One, which does have a fan (and otherwise the same network card).

If I could design an adapter PCB myself, I would go straight to OCP 3.0, which allows for a much simpler construction, and TB5 speeds.

Alternatively, there are DELL CX422A rNDC cards (R887V) that appear to have an OCP 2.0 connector but a better heatsink design.

Yes! However, I got around 15 Gbps with a Thunderbolt-only setup (TB3/TB4) = only 75% of the Ethernet setup.

You'd also mostly be limited to short cables (1-2m) and a ring topology.

Yeah, it's because the network card adapter's heatsink is sandwiched between two PCBs. Not great, not terrible, works for me.

The placement is mostly determined by the design of the OCP 2.0 connector. OCP 3.0 has a connector at the short edge of the card, which allows exposing/extending the heat sink directly to the outer case.

If somebody has the talent, designing a Thunderbolt 5 adapter for OCP 3.0 cards could be a worthwhile project.

Remote Time Machine backups are snappier than ever before :)

I was hoping somebody would suggest that (and eventually try it out).

With TB5, and deep pockets, you might probably also benchmark it against a setup with dedicated TB5 enclosures (e.g., Mercury Helios 5S).

TB5 has PCIe 4.0 x4 instead of PCIe 3.0 x4 -- that should give you 50 GbE half-duplex instead of 25 GbE. You would need a different network card though (ConnectX-5, for example).

Pragmatically though, you could also aggregate (bond) multiple 25 GbE network card ports (with Mac Studio, you have up to 6 Thunderbolt buses, so more than enough to saturate a 100GbE connection).

I don't know how to measure the direct power impact on a MacBook Pro (since it's got a battery), but the typical power consumption of these cards is 9 W, not much more than Aquantia 10 GBit cards.

Also, if you remember where you saw that logo, please let me know!