Cable tourment!

Posted on 2003-03-30
Medium Priority
Last Modified: 2013-11-09
I would be grateful for any help on this matter before I go insane (if I'm not already!)

I'm trying to connect 3 PCs using a switch and I had the great idea of making my own cable!  I'm using Cat5 UTP cable and one of computers I'm trying to network is downstairs so the cables probably about 30 metres long.  My problem is that I just can't get this 30 metre cable to work, I try to ping and I get the dreaded 'request time out'.  The cable doesn't work not matter which computers I connect it to and I have 2 shorter cables that do work!?!  The cable runs up the stairs so it doesn't go outside, I've checked that the strands are in the same order each end, I've tried changing the RJ45's each end, I've even tried cutting some more cable and starting over again and I just can't get it to even ping!

Does anybody know where I'm going wrong?  I suspect it is the cable but I just don't know what I've done wrong!  I've made network cable up before and never come accross this kind of problem, although not for a while and maybe I'm forgetting something really stupid!
Question by:janehome
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Expert Comment

ID: 8234025
You said the other two cables work - have you truly tested these cables on the computer that is downstairs (by moving it and one of the other computers closer together)?  -You know what I'm getting at, right?  -We need to rule out the Network Interface Card (NIC) on the computer downstairs.  -If you know that the NIC DOES work on the downstairs computer, are you plugging its run into an uplink port on the switch, instead of a regular port?  Often, there's an 'uplink' port on one of the regular ports.  Then, there's a little rocker switch or button to tell the device to run that port straight-thru, or crossed-over.  Check that.

Last, on that cable you're making, make sure your wires are 'faced' up to the end of the RJ45 connector.  -looking at the end, with all your wires properly oriented and slid into the plug, you should be able to see the copper ends of each cable thru the plastic. -They should be flush right up to the front of that connector, before you crimp.

Good Luck!



Accepted Solution

jwelter earned 1000 total points
ID: 8234029

Expert Comment

ID: 8234096

Does the 30 metre cable give a link? Or is there no link at all?
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LVL 28

Expert Comment

ID: 8234138
Do you have a cable tester?  When ever you make your own cables, you should always test them with a cable tester.  You can buy an inexpensive one starting about $35.

Author Comment

ID: 8234143

Thanks for the comments!

I have tested the NIC on the computer downstairs, and I tested the cable on the two upstairs computers and still nothing!

The cable isn't plugged into the uplink port and the cable is flush to the end of the RJ45 (can see copper for all strands on both ends!).

When the cable is connected I get a flashing green light on my NIC and a green light on the switch, and interestingly I get a message on my computer when I unplug the power supply to the switch which would make you think that some data is getting through!?!

I would be grateful for any further comments!
LVL 41

Expert Comment

ID: 8234287
>I have tested the NIC on the computer downstairs, and I tested the cable on the two upstairs computers and still nothing!
does the NIC work on the other machine?
take a known good cable and connect it
the trick is to eliminate one or the other
try a different pci slot on the machine, also swap out the NIC with a known good one
andforce the NIC to 10 mbit, half duplex for testing
are you using dhcp or static ip's?

Expert Comment

ID: 8234502

Can you tell us more about the speed and type of the HUB, and the NIC? Also check what the settings of your NIC on the malfunctioning pc are (10Mbit,100Mbit;full duplex,half duplex)...


Expert Comment

ID: 8236191
First things first.  There's more to making a network cable that simply making sure both ends have the wires in the same order.  You have to keep the pairs straight, what that means is don't just go and do straight pairs down the cable, and don't do pairs running from the outside in.  The pairs are specific, although the colors can be interchanged as long as the color are the same at the other end.  What you need to end up with is pairs that run like this: http://www.webtrader.ie/images/568ajck.gif

1-2 pair
3-6 pair
4-5 pair
7-8 pair

So, the two outside pairs are together, but the inside two straddle each-other (a pair inside of a pair)

If you don't do this, long cables will not work well as the data trasmitting lines want to be matched with their own ground, not another ground, it helps keep noise down without needing shielding.

Expert Comment

ID: 8242401
From what you've said, I'd bet that jwelter and matguy have given you the right answer.  Unlike telephone lines, the color code is vital on CAT-5.  What's rather disturbing is that you don't really run into major problems with an incorrect color code until you try making a cable longer than about 10 feet.  Then you get that really interesting "I've got link lights, but I can't pull a valid IP!" sort of problem.

Verify your color code.  (There are two standard color codes:

white/orange, orange, white/green, blue, white/blue, green, white/brown, brown


white/green, green, white/orange, blue, white/blue, green, white/brown, brown.)

Use the same color code on each end for a straight-through cable, or use a different one on each end for a crossover cable (to connect two computers together directly without a hub, router, or switch).

Good luck, and let us know how it turns out!

Expert Comment

ID: 8255133
just observed the straight through utp color coding!


just make it sure that the nic light blinks, as well as the hub light wherein the other end of the utp is located.

try to twist the utp end in the rj45, maybe its to loose when you crimped it. or you haven't stripped off an inch of the cable!

Expert Comment

ID: 8257494
Actually, the presence of blinking lights on the Nic and/or the hub only signifies a electrical link, but doesn't tell you anything about the quality of the link or integrity of the data.

Expert Comment

ID: 8296728
How's it going, janehome?  Gotten anywhere or any new info to update us with?


Expert Comment

ID: 9152797
This old question needs to be finalized -- accept an answer, split points, or get a refund.  For information on your options, please click here-> http:/help/closing.jsp#1 
Post your closing recommendations!  No comment means you don't care.

Expert Comment

ID: 10088761
No comment has been added lately, so it's time to clean up this TA.
I will leave the following recommendation for this question in the Cleanup topic area:

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