Wandering Thoughts archives


A pleasant surprise with a Thunderbolt 3 10G-T Ethernet adapter

Recently, I tweeted:

I probably shouldn't be surprised that a Thunderbolt 10G-T Ethernet adapter can do real bidirectional 10G on my Fedora laptop (a Dell XPS 13), but I'm still pleased.

(I am still sort of living in the USB 2 'if it plugs in, it's guaranteed to be slow' era.)

There are two parts to my pleasant surprise here. The first part is simply that a Thunderbolt 3 device really did work fast, as advertised, because I'm quite used to nominally high-speed external connection standards that do not deliver their rated speeds in practice for whatever reason (sometimes including that the makers of external devices cannot be bothered to engineer them to run at full speed). Having a Thunderbolt 3 device actually work feels novel, especially when I know that Thunderbolt 3 basically extends some PCIe lanes out over a cable.

(I know intellectually that PCIe can be extended off the motherboard and outside the machine, but it still feels like magic to actually see it in action.)

The second part of the surprise is that my garden variety vintage 2017 Dell XPS 13 laptop could actually drive 10G-T Ethernet at essentially full speed, and in both directions at once. I'm sure that some of this is in the Thunderbolt 3 10G-T adapter, but still; I'm not used to thinking of garden variety laptops as being that capable. It's certainly more than I was hoping for and means that the adapter is more useful than we expected for our purposes.

This experience has also sparked some thoughts about Thunderbolt 3 on desktops, because plugging this in to my laptop was a lot more pleasant an experience than opening up a desktop case to put a card in, which is what I'm going to need to do on my work desktop if I need to test a 10G thing with it someday. Unfortunately it's not clear to me if there even are general purpose PC Thunderbolt 3 PCIe cards today (ones that will go in any PCIe x4 slot on any motherboard), and if there are, it looks like they're moderately expensive. Perhaps in four or five years, my next desktop will have a Thunderbolt 3 port or two on the motherboard.

(We don't have enough 10G cards and they aren't cheap enough that I can leave one permanently in my desktop.)

PS: My home machine can apparently use some specific add-on Thunderbolt 3 cards, such as this Asus one, but my work desktop is an AMD Ryzen based machine and they seem out of luck right now. Even the addon cards are not inexpensive.

tech/Thunderbolt10GSurprise written at 23:07:03; Add Comment

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