very strange cat 5e problem

[ceeYx]

this week i have had very weird problems with cabling
i work for a small isp and cat 5 cables are my everyday job
the problem itself is as follows

1. i make a standard cable

w/orange
orange
w/green
blue
w/blue
green
w/brown
brown

2. when its all done and tested, it doesn't work
and it is a new cable, i checked the connectors on both ends and they both are fine

3. when i remake the cable with following configuration it works perfectly

w/orange
orange
w/green
blue
w/blue
green
w/brown
brown

in one end and

orange
w/orange
green
w/blue
blue
w/green
brown
w/brown

if anyone out there has had similar problems i would apreciate it if someone could shed a little light on the subject, I'm out of ideas why this could happen

 

[ttech]

On most Cat5 and Cat5e jacks there is an extra twist inside of the jack on conductous that the pair are parallel to each other.(oranges blues and browns the greens are not twisted in the jack besause they are separated by the blue pair

ICC jack for example are punched down as

Orange|Wh/OR|Wh/green|Wh/blue|blue|green|brown|wh/brown
\ / | \ / | \ /
\ / | \ / | \ /
X | X | X
/ \ | / \ | / \
/ \ | / \ | / \


Pin1 Pin2 Pin3 pin4 pin5 pin6 pin7 pin 8



as you can see the inside the jack are twists

 

[franklin97355]

If the cable tests OK (with a quality tester) then the problem is with your equipment not the cable.

 

[hbiss]

If you wire both ends the same that is correct. If your tester tells you something different it is the tester that is the problem.

-Hal

 

[franklin97355]

Hal, in his first post it sounded like he was making a straight through patch cable and he said it tested OK. That was what I was referring to.

 

[wires]

Very strange.

I assume you are making a patch cable with plugs (no jacks) on both ends. As pointed out by ttech if you are using jacks the order for connecting the cable in most cases is different from the pinout of the jack.

To better understand your problem I need clarification on the statement "when its all done and tested, it doesn't work".

1. What sort of tester are you using?

2. Do the cables pass testing?

3. How long are the cables?

4. What equipment is being connected with these cables?

I just tried an experiment by wiring a patch cable the way you described in the second part of your post. It works fine for connecting a PC to either a switch or hub. I half expected it to function since all you are doing is swapping the wires of a ballanced line pair. Most modern 10/100BaseT equipment should be able to handle such a problem. Both a Microscanner and Omniscanner flunked the cable as expected.

I am very interested to hear exactly what you are doing so I can understand why a swapping polarity on pins 1,2 and 3,6 have such a dramatic effect.

 

[ceeYx]

well the cable is aprox. 10 meters long
i tested it with trendnets cable tester TC-NT2
and today i made another cable on another site
also a standard cable from the same box as the last one
and it worked fine.
Once there was a problem with cable, kinda weird anyways,
the cable had a shortcircuit in it from the factory, one pair was made longer to continue the cable. i noticed it because it felt strange in one place, afterwards when i opened it it was nicely taped and from visual inspection from the outside u couldn't tell the difference.
anyways with current cable it's not the issue.

i also have tried to switch pairs in one end as i had to do on my first post and it worked in both ways(the standard and switched colors)

i guess it's going to be a puzzle for long

 

[mforrence]

We're all assuming that the device using this cable is a computer. However, if it is an old telephone, the cable that you describe in your initial post is essentially a USOC crossover cable. Most older telephones use such a crossover cable somewhere along their cable channel - usually in the form of the line cord from wall to telephone.
Mike

 

[ceeYx]

ups forgot

it is cable from switch to PC

 

[Dante808]

Try another port on your switch. If not your ports auto-configuration seems messed up.

 

[Dante808]

Anyway judging by the quality of your cabling the quality of your hardware comes into question too. When that happens it would by next to impossible to find a problem and not worth it IMO.

Switch vendors.