ethernet diagnostic software

Posted on 2012-08-10
Last Modified: 2012-08-17
I believe there's a network drop that's having problems, and I'm wondering of there's free software out there that will monitor the connection and show any errors?

I have to prove to the support person that the drop itself is having problems before anything is done.

Maybe this is measured in bad packets or some other way? This is Windows 7 professional x64. Is there anything included w/ Windows 7?

I've changed all the ethernet cables out w/ new ones but still seems to have problems. I don't have a physical meter I think it's called.

Question by:kevluck373
    LVL 13

    Expert Comment

    ping -t  

    Or are you looking at a traffic capture?  Or the stability of the network card itself?
    LVL 17

    Expert Comment

    by:Lior Karasenti
    LVL 24

    Accepted Solution

    Multiple simple ways to determine the issue

    1) Connect a different pc/laptop to same cable - does it drop? If yes then its not your laptop/pc. If no, then its your laptop/pc nic...

    2) Next move cable to a different wall socket/switch port on your switch - does it drop? If yes then it could either be switch issue, or more than likely the patch panel that the 2 sockets are feeding back to is dodgy - if no, then its still an issue with the original cable run(possibly from the wall socket back to switch panel/port)
    LVL 23

    Expert Comment

    This can and should be reviewed on a managed switch/network device that the computer is plugged into,  by checking the various Error counters and Up/Down or carrier transition counters for the switch port.

    If you have an unmanaged switch and no electrical test equipment, your options are quite limited, for proving the drop is the problem,  and not the computer, software, the NIC, or switch.

    Honestly, if you are expected to troubleshoot a possibly bad drop,  you should get test equipment,  OR  your organization should have a firm agreement with whoever is supporting you,   that they have to  fully  electrically test the drop using a T568A or B cable qualifier/certifier,  for shorts, improper wiring, electrical characteristics out ouf spec, etc,  when a drop issue is strongly suspected, reported and testing requested.

    One possibility would be to unplug  the patch cable for that computer from the switch and plug a laptop in via cross-over cable, send a LOT of traffic in both directions, and monitor for errors or link loss on either side.

    e.g.  temporarily plug in a laptop running Linux on each side of the drop and run iperf tests between the two nodes,  to rule out anything besides a broken drop and broken patch cable.

    A commercial alternative would be running PassMark's  network benchmark tester over an extended period

    Then check for errors using the same  Windows 'netstat -e'  or   Linux 'ifconfig'

    Check for no loss at the expected performance, and check error counters using the  'ifconfig'  command.

    On Windows systems,

    You can check  interface statistics from Windows'  point of view with  Start >  
    Run  cmd.exe  as Admin

    netstat -e

    C:\>netstat -e
    Interface Statistics

                               Received            Sent

    Bytes                    3773212228       774519448
    Unicast packets           189659759        86219169
    Non-unicast packets       745008871         2835831
    Discards                          0               0
    Errors                            0               0
    Unknown protocols                 0


    The line that says "Errors"  shows the count of erroneous packets received that were discarded.

    "Discards" shows packets discarded to congestion.

    Note, that "Errors" is one way, and only shows Errors on the receive side,
    only the remote side knows if packets that you sent were erroneous  after they crossed the wire,   so you absolutely need managed devices on both sides.

    Either control of the Workstation and a Managed switch at the other side of the drop,
    or  two  computers   or other test devices at each end of the drop,
    so you can check if error counters are incrementing  while transferring data,
    or connection resets are occuring,  as an indication of problems being present.

    Author Closing Comment

    Sorry it has taken me sometime to get back, but I never thought of trying another NIC.

    It's hard to say if the other NIC was the %100 fix because I was able to ping As far as I know the drivers were the latest.

    All I know w/ the NIC that was in there for some reason never stopped sending data to the printer. You'd look at the print spool in Windows and the size of the print job always kept changing size therefore printed 50 pages or so just for a test page.

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