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I have heard mixed answers regarding this question. I think historically the answer is "yes", but modern ethernet controllers allegedly support discovering devices by enumerating the twisted pairs in the cable to determine their orientation.

That said, I do not actually know the answer for certain. So, for a connection like this:

laptop <---> laptop

As opposed to

laptop <---> switch <---> laptop

Is it necessary to use a special crossover ethernet cable?

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  • Depends on the specific equipment. There is no single answer to your question that applies to all situations.
    – sawdust
    Oct 31, 2019 at 2:30

1 Answer 1

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Modern Ethernet connectors and switches (10 years old or newer) detect the proper cable connection called for so crossover cables are not necessary any more.

That said, connecting via a small switch is a much better way to make a connection. Small switches are very inexpensive and can be used in a variety of situations

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  • I just have one small board computer I need to talk to over the network. And my laptop docking station has an unused ethernet port. But for some reason I can't get the two to communicate. I thought maybe this was it, but also had heard it was no longer necessary.
    – sherrellbc
    Oct 31, 2019 at 0:47
  • You need to look at the network connections and you may need to connect by IP address. Still, if you can manage, a small switch is invaluable
    – John
    Oct 31, 2019 at 0:51
  • I assigned the interface an IP address and started DHCP with a range of 1 distinct IP address to lend. Still no connection. A switch would be nice, I just don't have one at the moment.
    – sherrellbc
    Oct 31, 2019 at 0:52
  • Perhaps try static IP addressing for this purpose. It has been a while but that is how I did it back then
    – John
    Oct 31, 2019 at 0:53
  • "But for some reason I can't get the two to communicate." -- Then you have posted an XY problem. You have an answer for your Y question. Stop asking Y questions, and ask your X question. BTW a laptop (as in your hypothetical problem) is not a SBC (as in your actual situation/problem). A PHY chip w/o Auto MDI/MDI-X is more likely on a SBC.
    – sawdust
    Oct 31, 2019 at 2:25

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