How to test: Ethernet physical port

Discussion in 'iMac' started by adam9c1, Oct 11, 2013.

  1. adam9c1 macrumors 65816

    adam9c1

    Joined:
    May 2, 2012
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    Chicagoland
    #1
    I'm working on an iMac.

    I think it passes the Hardware Test (another tech did not say it failed).
    I did a clean install of Lion and ML on an external USB drive.
    Under both installs I do not see the icon change to green, I'm unable to get IP, the state says unplugged.

    Will a physical loopback adapter test the connection if I hardcode IP?
     
  2. Bear macrumors G3

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    Jul 23, 2002
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    Sol III - Terra
    #2
    Have you tried more than one ethernet cable? Maybe you're plugging into a bad port on the other end. Whatever you're plugging into.
     
  3. adam9c1 thread starter macrumors 65816

    adam9c1

    Joined:
    May 2, 2012
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    Chicagoland
    #3
    I plugged in different cables to different ports of an unmanaged switch.
    I have also plugged in a cable to a wall jack (wherever that goes).

    I have also tried to force set (randomly) different speeds and duplexing (did not try all the possibilities).
     
  4. Bear macrumors G3

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    #4
    You said the icon doesn't go green? What icon are you talking about? What color is it? Also, grab a screenshot of the window you're talking about and post it here.
     
  5. adam9c1 thread starter macrumors 65816

    adam9c1

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  6. Bear macrumors G3

    Joined:
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    #6
    It is possible the the iMac could have a bad ethernet port and still pass the tests.

    First thing you might want to do is look at the ethernet port on the iMac and see if the wires in it appear to be in the right place and not mangled.

    Second, take the problem machine and connect it to a known working port and cable that you've just tested with another Mac.

    And finally if you didn't run the hardware test yourself, you might want to do so.
     
  7. marsmissions macrumors 6502

    marsmissions

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    Location:
    Washington, US
    #7
    Switches and Wall ports don't always assign IP addresses using DHCP, you may need to assign that on your own to get a connection.
     
  8. RedReplicant macrumors 6502a

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    Mar 31, 2010
    #8
    What is the setup you're trying to do here? If you're plugged into an unmanaged switch that isn't connected to anything else then you're not really connected to anything.
     
  9. Bear macrumors G3

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    #9
    If the iMac had a physical wire connected to another device, it would not say "Not Connected" it would say something more like no ip address assigned.

    As said, wouyld still have the electrical connections. I suggested using a known working port and cable to eliminate everything outside the Mac.
     
  10. adam9c1 thread starter macrumors 65816

    adam9c1

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    #10
    I took the screenshot shortly after disconnecting the USB - Ethernet adapter.
    That's probably it still says set for DHCP.
     
  11. Bear macrumors G3

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    Jul 23, 2002
    Location:
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    #11
    A screenshot when it isn't connected to a network port isn't as useful as one from when it is connected as is might have been yellow or it might've had a useful status shown.
     
  12. RedReplicant macrumors 6502a

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    Mar 31, 2010
    #12
    Try it, plug a computer into a -switch- as the only thing plugged in to it. The machine will report network cable unplugged.
     
  13. FreemanW macrumors 6502

    Joined:
    Sep 10, 2012
    Location:
    The Real Northern California
    #13
    Here's an idea . . .

    1) Bring a known to be functional computer into the mix.
    2) Nail down a working network and then troubleshoot the iMac.
    3) Profit.
     

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