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Modern cables (if you buy high quality ones) support incredible lengths - this is relatively easy to do in many situations.



Except, of course, for Thunderbolt 3, where to get even reasonable lengths you have to pay $$$.

https://www.theverge.com/2020/7/27/21339861/apple-thunderbol...


What's the deal with these prices? Is it just because the connector is so compact? A 2-meter QSFP+ 40-gigabit copper cable is only about $25.

https://www.fs.com/c/40g-qsfp-dac-1117


One very major difference is, Thunderbolt's spec requires that this cable carry 100W of power in addition to the 40Gbps of bandwidth.


Power over Ethernet is not too far from 100W. Maybe around 70, if I can recall correctly. So the power isn’t the biggest factor I think


PoE only works on 4-pair UTP though. It's not going to work over twinax!


Nope. Standard PoE is 15.4 watts.


That one came out years and years ago, new one IEEE 802.3bt 4PPoE does up to 71.3W


They are "active" cables and so have microcontrollers in them.


But isn’t that an indictment of the whole architecture? 40-gig Ethernet reaches these distances with passive cables.

Is it that the Ethernet people have moved the costs into the port and their ports cost more, while the thunderbolt ports cost less and the cables cost more?


Never seen a consumer motherboard with 40Gb Ethernet. Even 10Gb is rare.

One criticism of Thunderbolt is that it already requires a fairly expensive separate controller on the motherboard except for a few Intel chips with built-in TB controllers.

Sending that much data that fast is going to cost more somehow or another.


Right, just thinking about the end-to-end economics. The TB3 add-in card for my HP workstation costs $200 for 2 ports. HP doesn't market a 40g ethernet card but an Intel model costs $400 at retail, also for 2 ports. Then I need either 2 $25 cables for ethernet or 2 $129 cables for TB3. It's the same price either way. Of course, the two setups don't accomplish the same things; they are comparable only in reach and speed.




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