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Troubleshooting bad jack 2

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ssampier

ISP
Sep 16, 2004
43
US
I am the sys admin of a small educational service center. I am the only computer/phone/anything-that-plugs-in person. I am having a little trouble trying to diagnose and troubleshoot a broken RJ45 network jack. When I plug any patch cable into the jack I do not get any lights on any NIC.

The jack itself has a cat5e cable that connect directly into the wall, from there it goes to the ceiling crawl space to our server room where it connects to one of layer 3 switches. However, I am not sure exactly where it connects to.

None of the cables are labeled (they list the port it's connected to). I have a toner and tone probe, but the toner probe signal sounds the same across most of the cables.

I know I have used this jack before in the past. How would you troubleshoot this problem?
 
The toner is half the solution. You also need the cat5 tester that verifies continuity and checks for crossed wiring.

The cat5 tester doesn't do some of the more sophisticated stuff you might need, but for around $50 it will show why things are dead.

Ed Fair
Give the wrong symptoms, get the wrong solutions.
 
Look at the lights on the switch to see which ones with patch cords are not lit. I would put the toner in the jack, and unplug the patch cordswith no light one by one from the switch to make it easier to identify the tone.
 
Something like this may work for you. This issue surley will justify the cost (think they run under 100)

You can pick that tester or something like it at any of your local cable supply houses like a Graybar.

Once this issue is resolved personally if it were me, any spare time I had would be dedicated to coming up with some sort of labeling scheme and get both ends labeled. Cables are moved from port to port all of the time so what you currently have isn't exactly friendly.
 
And don't forget to throw that new cat5 tester on your patch cable too - doesn't matter how good the run to that closet is if your patch cable is broke.

And make sure the network device works in another known good location.

And, as a matter of course, I probably would have already re-punched that jack connection...
 
And don't forget to throw that new cat5 tester on your patch cable too - doesn't matter how good the run to that closet is if your patch cable is broke.

good point

I always test patch cord end to patch cord end with the patch cords that will be used .
 
There are a couple of steps in this process of elimination:
1. change the patch cord see if it works
2. if not then plug another device into the jack and see if it works
3. if not then re-punch the jack and plug in the orginal device/patch cord
4. if it still does not work, check the switch end of the cable for connectivity
Good Luck,

Has been in the cabling business for about twenty years and is now the Sr PM for a cabling company located in the Los Angeles area.
Also a General Class Amatuer Radio Operator.
 
If you run your tone on a split pair in the cable you will pick up a better sig
 
Even better signal if you put one toner lead onto cable and other lead to good earth ground.
Mike
 
Very good points everyone. I did try several different patch cables. In addition, I made sure to try the very same patch cables into a different computer. Still no NIC light.

I do have a cable tester (TRENDnet Cable Tester 10/100 COAX and TP TC-NT2). If I knew exactly where the cable connected, I could remove it from the switch and place the tester and terminator on each end. Is there another way to use it?

I will retry punching down the connection again. I will also look into trying the toner again (using the alligator clips instead of the RJ45).

I appreciate the help. I will let you know how things turn out.
 
Depending on the type of toner you have, it probably is sending tone over just one pair. If that pair is shorted or broken you wont be able to tone it out. Try opening the jack and putting you alligator clips onto white/brown. Also, the layer switch wont send any signal over the brown pair so you wont get anything shorted.

What doesn't kill you only makes you stronger.
 
Many switches have a config option to enable 2 or 4 pairs. If 4 pairs are enabled on that port, your tone will be "eaten"- you'll hear it on every cable on that switch. I prefer to test by link when I know a cable is patched. Check the link status of the switch with that cable plugged into a PC, then unplug it. If your LED's change, trace back the patch cord on that port to locate your cable, and test it.

It'd probably be a good idea to relable all your jacks with the patch panel port, rather than the switch port this way. That's industry standard, and makes troubleshooting soooo much easier.
 
We have cleaned up many companies with the following procedure. This will help you identify your cables and allow you to test in the future.

OVER A WEEKEND:

1) Verify your patch panels are labeled in order 1,2,3...
2) Remove all the patch cables from the SWITCH/HUB end ONLY.
3) Leave the other end of the patch cables plugged into the patch panel. (This is done so whoever was active will remain active when you’re done)
4) Have another person with a 2 way radio plug in a toner at every jack location.
5) You can identify that location at the patch panel and let the other person know what jack number it should be.
6) Have him label the jack.
7) After you have toned and identified the cable, now would be a perfect time to test with your tester.
8) Plug in the hanging end of the patch cable back into an available switch/hub port. Now is also a good time to route the patch cables through the wire management neatly.

Note: The reason one end of the patch cable is removed (step 2) is so you can properly hear the tone on ONE cable only.

Now your wired data network is labeled correctly and future testing will be much easier.


 
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