No Link With Crossover Cable?

Discussion in 'UDOO NEO' started by ctassell, Jul 19, 2019.

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  1. ctassell

    ctassell UDOOer

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    Hi Everyone,

    I have a strange one here. I have two Udoo Neo's connected with a crossover Ethernet cable and I'm getting no carrier on eth0. If I plug those same two Neo's into a switch, with the same configuration, they work fine. I'm running Debian on the Neo's, but this shouldn't be a software issue. Is there something funny about the Udoo Ethernet chip that it doesn't like direct cabling?
     
  2. waltervl

    waltervl UDOOer

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    I suppose this is because there is no IP address assigned when you use 2 Neo's connected to each other. When connected to the router they will get an IP address from the router.
    You will have to modify the file /etc/network/interfaces on both Udoo Neo's so they will get an unique static IP, each within the range of your router (for future connections).
    There is enough information onliner how to set static IP on the Udoo Neo.
    You could start with this https://www.udoo.org/forum/threads/tutorial-newbie-how-to-set-static-ip-in-ubuntu.651/
     
  3. ctassell

    ctassell UDOOer

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    No, it's not a software issue (at least not a simple one.) I have assigned static IPs to the Neo's and plugged them into a switch and they work fine. But when I use a crossover cable (I've tried with 2 different cables and put one of them through a cable tester) I get "NO CARRIER" with "ip addr show dev eth0" I've confirmed that the IPs are still there on both Udoos, I've run "ip link up" but that doesn't make a difference. There seems to be some issue that the Neo won't recognize an Ethernet connection unless there is some sort of signalling from the other end that the Neo itself won't provide.
     
  4. sirrab

    sirrab UDOOer

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    Perhaps a "straight" thru Ethernet cable will work.
     
  5. ctassell

    ctassell UDOOer

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    Yeah, I tried a straight through Ethernet cable originally and thought it was odd that it didn't work (haven't seen an Ethernet device that didn't have auto-MDIX in years) so that's why I tried the crossover. I have even tried this with two different pairs of Neo's and no luck, so it's something about the hardware. I'm wondering if it's a power thing (neither Udoo being willing the first to send current) or just some sort of unimplemented handshake feature that is messing it up.
     

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