How can I test if my data cabling, punch-downs & jacks are 100%?

Discussion in 'Networking' started by DrStein99, Jun 10, 2018.

  1. DrStein99

    DrStein99 Member

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    I know when I run a cable, punch it down, crimp, and plug the two ends into this LED tester, the lights indicate that I have a good connection on each pair. Then, I plug into my switch & server / computer - and the link goes up 1gb, connect all good.

    Is it all good at that point ? I do not know. What happens if someone shuffles a cabinet around, shakes a cable somewhere, bumps up against the a cable in patch panel, or there was some microscopic corrosion on any of the terminal connects? I am skeptical.

    Is there a log in Linux (outside of the standard syslog) I can check to see about any errors in my packets, or anything that would suggest I have line noise or a not-so-good connection? Am I just being overly cautious and paranoid?
     
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  2. pricklypunter

    pricklypunter Well-Known Member

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    If doing this at home, a quick check with a cheapie cable tester is about as far as you need go. After that, it either works or it doesn't. If on the other hand you are doing this as a professional installer, then you'll need a good meter that you can use to verify the wire/ cable run with. A good meter will run a battery of tests, everything from checking for split pairs to TDR to measure discontinuities and length to checking for near and far end crosstalk and etc. Patch cables at the panels can also be checked, both in and out of circuit.

    As for what happens when you bump up against terminations, like most things in life, there is a multitude of possibilities. If it fails either now or later, it will be pretty obvious to the end user. It may even be that the user ran over their patch cable with their chair for a week beforehand, without even thinking about the outcome of doing so. Environment also plays a part here, anywhere that moisture levels are high needs due consideration. Sometimes you'll get a poor connection at a panel developing due to dust, moisture and oxidation occurring on the terminals. A quick pull and re-insertion of the jack is normally all that's needed to clear such things, at least until it happens again :)

    If you are concerned about errors, you could use a packet sniffer like wireshark on a mirrored port at the switch to log specific traffic for later inspection, or the switch itself may even be capable of logging such events. Generally though, fixed horizontal and vertical wiring when properly specified and installed is rarely an issue later, without some unforeseen event occurring like rodent damage or a misinformed contractor cutting through something. Patch cables on the other hand, move the responsibility of proper care into the hands of end users. Most of the time I see infrastructure issues it's either bad patch leads or chatty NIC's (Flapping).

    All that said, life happens, nothing is forever, faults occur, you just have to troubleshoot and deal with them as and when :)
     
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  3. Jerry Renwick

    Jerry Renwick Active Member

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    You will need a cable tester to troubleshoot the cable faults.
     
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  4. DrStein99

    DrStein99 Member

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    Ok I think I got it. I have a LED cable tester which shows the basic connection of all the pairs have continuity. I have experience punching these down, its not my first time. I just wanted to expand my knowledge of other tools I was not using that could give me some more information.

    Ok, well that will wrap this question up. I got your advice, so if it works for 15 minutes - it will probably work forever.

    As far as the wire-shark goes, I have been there. That is a waterfall of information that is so overwhelming. I find myself reading the all the messages all night and forgetting to go to sleep, like when DEFRAG was first invented and I watched the entire animation from end-to-end on a whole 20mb hard drive.

    Mostly what I have learned was when I had friends and co-workers around with me to share their knowledge. I use wire-shark when I'm debugging my UTP/TCP code to trace messages.
     
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  5. Priscilla110

    Priscilla110 Member

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    A cheap cable tester is a must for troubleshooting. It can test the situations like the breaking at the set point, the short circuits, the gross pair wire, and the split pairs as well as the reversed pair wire, etc.
     
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