[CS-FSLUG] Ethernet Testing

Tim Young Tim.Young at LightSys.org
Wed Sep 5 07:39:49 CDT 2012

Hi there,
A cat5 cable does not have "grounding" the same way that an 
"Cable-TV" cable has.  So that should not enter into this.  You 
should be able to ignore the grounding light.

Oddly enough, there is just one pin that needs to be connected for 
the "connection light" to be turned on.  BUT, it needs to go from one 
of the TX (transfer) connections to an RX (receive) pin.  Thus, if 
you do not have a crossover cable, and you need one, the light never 
turns on.

If your tester is actually working (and there is always a small 
chance that the tester is bad), then it seems to be showing you that 
your wire is connected.  This is step 1.  This does not mean that the 
wire is good, but rather that the ends are connected.  This is all 
the device should need to give you a connection light.

If you have issues with cable-length, fluorescent lights giving 
noise, buried electrical cables giving noise, etc.  All of those 
should give you "errors" on the device interface statistics.  It 
should not change the status of the connection light.  Unless the 
voltage drop is so huge across your cable that your device cannot 
sense the other end, it should connect.

The first test should be to take the two devices and plug them 
straight into each-other with a short cable that your tester says has 
the same pinout as your long cable.

     - Tim Young

On 9/4/2012 11:56 PM, Timothy Butler wrote:
> Hi, Tim,
> 	I believe the pins are in the correct order. I'm using a Linksys router, which, I believe can automatically switch between crossover and not, although I didn't test these two particular units (I tried two WRT54G's) on a short cable to the same switch. Good idea!
> 	The tester has 8 lights and a grounding light on both ends. On each end, each light should light in sequence -- one at a time -- if the cable is good. It did so on this cable.
> 	Thanks!
> 	Blessings,
> 		Tim
> On Sep 4, 2012, at 10:05 PM, Tim Young <Tim.Young at LightSys.org> wrote:
>> Hi there,
>> I am assuming that, with your tester, all of the lights show that they are connected to their respective pins?
>> 1 - 1
>> 2 - 2
>> 3 - 3
>> 4 - 4
>> 5 - 5
>> 6 - 6
>> 7 - 7
>> 8 - 8
>> Or how does your tester show it is working?
>> If all your pins are connected this way, and you are not getting any lights at all on the WAP, my first guess is that you need to have a "crossover" wire instead of a straight-through.  But that is easily tested.
>> Can you: take another, short wire and plug it into the SAME port of the switch and the SAME port of the WAP and see if it lights up or behaves in any way differently than your buried cable?
>> If it does not work, you can see if a single port of your switch is a "crossover port".  Some older devices were this way.  If this is the case, and you need your crossover to connect your switch to something else, you may need to rewire the cable to be a crossover cable.
>> If it is not an issue with a crossover cable, then I would need to hear "how your tester says it works" before I try to give more advice for testing, etc.  :)
>>     - Tim Young
>> On 9/4/2012 10:44 PM, Timothy Butler wrote:
>>> I am trying to run Ethernet over a buried Cat 5e cable that worked OK with my cable tester I bought on Amazon (http://www.amazon.com/gp/product/B000P1OA1O/ref=oh_details_o01_s00_i00). However, when I plug a wireless access point in at the far end and plug the end by the existing network into a switch, nothing lights up on the switch end and the WAP's lan light blinks but never goes on solid.
>>> Any suggestions how I can figure out what is going wrong?
>>> I have a few suspicions:
>>> 1.) The wire is damaged underground (I hope not, because the conduit doesn't really have room for another cable pull).
>>> 2.) The ends have been stripped too far back. The twisted pairs were untwisted and the outer sheath removed for a foot or two of the cable that was wound in the box at the end of the conduit. Do you suppose this might be introducing too much interference? I hate to cut off all this extra cabling if I'm not certain this is the problem, but I'm suspicious...
>>> Thanks for any suggestions you might have...
>>> Blessings,
>>> Tim
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