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I am using Ubuntu 12.04 and I made changes on Interfaces file to change the IP of my touch computer. After reboot everything works well if I am connected with normal Ethernet cable to a Hub or router, but when I am using an Ethernet crossed cable to connect directly to another device, and I restart, I found that eth0 is down.

It would be probably due to some hardware problem that is not detecting the power up pin at start-up.

I guess that I can solve it by using ifup eth0 on a script after power-on, but if you have some other suggestion it would be really useful.

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    How old is your PC ?
    – HungryFoolish
    Jun 25, 2015 at 11:02
  • @RishavAmbasta the touch computer is new, but due that is on an industrializated context, hardware is the same for last 8 years (approximated). They are making an update of the hardware soon, but it isn't applied. Checking the technical catalogue of the product I see that it is using Intel 82574L connector for RJ-45 cable, so it seems compatible with the crossed cable.
    – Bepo
    Jun 25, 2015 at 11:17
  • I am starting to think that what is wrong is the cable, I am going to check it and later I will update the issue.
    – Bepo
    Jun 25, 2015 at 11:21
  • While this may relate to 'crossed' Etherenet cable, if could also be an ad hoc IP-network issue. What hardware (brand/modeL)? Why are you not using 14.04 LTS? What device are you attempting to connect (ad hoc) to this 'touch computer'?
    – david6
    Jun 25, 2015 at 12:02
  • @david6 I am not using the 14.04 due to a problem with a driver, which intel does not create it and touch system didn't worked. I thought that it is related to the cable because I see that the one that I was using isn't a normal crossed cable (T-568A or T-568B). It is a T568A-T-568B and I thought that due to different colors, some problem could happend here, but it don't. When I am working in DHCP, interfaces remain "up" after reboot, but they don't when I am working with an static IP. I'll check with the supplier to see if they has this issue known. Hardware model is LPC-1205 from Avalue.
    – Bepo
    Jun 25, 2015 at 13:55

1 Answer 1

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Cross cables and straight cables are two different types of Ethernet cables which are used in connecting network equipment and devices with each other.

Starting from the early days, equipment used to transfer data in one direction only and different product companies mentioned which cable is compatible with the product. Modern Ethernet cables are 8-strand, 4-pair, twisted-pair cables. Of those individual wires inside the cable, only four of the eight cables are used to transfer data - two for transmitting and two for receiving.

Most modern Ethernet networking interface cards are designed to be autonegotiating and can usually determine which wires to send the data over. However, older equipment may not be able to do this.

You may need to use a standard straight Ethernet cable instead, or try and connect a switch or hub between the two instead.

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  • Readability is key - don't lump everything in one wall of text. Also grammar is helpful.
    – Thomas Ward ♦
    Jun 25, 2015 at 11:13
  • From a technical perspective, if OP's computer can't negotiate data over a crossover cable, I"m not sure connecting a hub or switch between the computer and the Ethernet device it's connected to will solve the issue.
    – Thomas Ward ♦
    Jun 25, 2015 at 11:14

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