ethernet cable problem

  • Thread starter Thread starter alice
  • Start date Start date
A

alice

So I'm trying to connect an XP PC to a hub. The port on the hub is
good. The cable is new and a tester shows that it is good.
When I plug the cable into the PC it says the network cable is
unlplugged.
I wondered if the NIC could be bad, but when I plug it into my laptop,
I get the same message, even though I know my laptop network adapter
is working properly.
I'm not sure what to try next, other than a new cable, but I can't do
that easily, it's a very long run and through walls etc. And besides,
the cable tests good, so how could a different one be any better?
Any ideas?
 
alice said:
So I'm trying to connect an XP PC to a hub. The port on the hub is
good. The cable is new and a tester shows that it is good.
When I plug the cable into the PC it says the network cable is
unlplugged.
I wondered if the NIC could be bad, but when I plug it into my laptop,
I get the same message, even though I know my laptop network adapter
is working properly.
I'm not sure what to try next, other than a new cable, but I can't do
that easily, it's a very long run and through walls etc. And besides,
the cable tests good, so how could a different one be any better?
Any ideas?
Click to expand...

I know its a bummer, but pick up the PC and move it to the hub and plug
in a standard 6 ft store bought cable and test it.
If it works, guess what, the cable in the wall is bad. Beats the
tester.

You give no info on the cable going through the wall. But pins 1/2 and
3/6 should be twisted pairs. If they are not you could have a
connection electrically but not when subjected to a data stream.

See this page. http://www.ertyu.org/steven_nikkel/ethernetcables.html

The transmit and receive pairs are twisted. Its a necessary feature.
 
alice said:
So I'm trying to connect an XP PC to a hub. The port on the hub is
good. The cable is new and a tester shows that it is good.
When I plug the cable into the PC it says the network cable is
unlplugged.
I wondered if the NIC could be bad, but when I plug it into my laptop,
I get the same message, even though I know my laptop network adapter
is working properly.
Click to expand...

Then you know it's the cable.
I'm not sure what to try next, other than a new cable, but I can't do
that easily, it's a very long run and through walls etc. And besides,
the cable tests good, so how could a different one be any better?
Any ideas?
Click to expand...

Bring the hub over to your PC, or move your PC closer, and plug it in.

If that works, the cable in the wall is bad. It can be just a loose
connection on the RJ45 jack at the wall.

Inexpensive testers aren't always reliable.

HTH
-pk
 
alice said:
So I'm trying to connect an XP PC to a hub. The port on the hub is
good. The cable is new and a tester shows that it is good.
When I plug the cable into the PC it says the network cable is
unlplugged.
I wondered if the NIC could be bad, but when I plug it into my laptop,
I get the same message, even though I know my laptop network adapter
is working properly.
I'm not sure what to try next, other than a new cable, but I can't do
that easily, it's a very long run and through walls etc. And besides,
the cable tests good, so how could a different one be any better?
Any ideas?
Click to expand...

If this is long cat 5 type cable that was punched down to blocks that you
plug in short cables to the computer, the person doing the work may not have
made good connections, could have made connections that created a crossover
cable (which would work as direct NIC to NIC connection but not to a switch)
The way to check if it is a crossover cable would be to hook up the two
computers directly to each end of the cable and see if you can get
connectivity between the two while not using the hub/switch.

One other thought is that you mention "hub". If this is of one particular
type you would still need a crossover cable to connect to the hub.
 
alice said:
So I'm trying to connect an XP PC to a hub. The port on the hub is
good. The cable is new and a tester shows that it is good.
When I plug the cable into the PC it says the network cable is
unlplugged.
I wondered if the NIC could be bad, but when I plug it into my laptop,
I get the same message, even though I know my laptop network adapter
is working properly.
I'm not sure what to try next, other than a new cable, but I can't do
that easily, it's a very long run and through walls etc. And besides,
the cable tests good, so how could a different one be any better?
Any ideas?
Click to expand...


Maybe you purchased a "crossover" cable by mistake
 
You give no info on the cable going through the wall.  But pins 1/2 and
3/6 should be twisted pairs.   If they are not you could have a
connection electrically but not when subjected to a data stream.

See this page.  http://www.ertyu.org/steven_nikkel/ethernetcables.html

The transmit and receive pairs are twisted.   Its a necessary feature.
Click to expand...

The wires on both ends are-
orange/white
orange
green/white
blue
blue/white
green
brown/white
brown
 
alice said:
The wires on both ends are-
orange/white
orange
green/white
blue
blue/white
green
brown/white
brown
Click to expand...
Sounds right. Orange/white and green/white pairs are in the right spot.

Have you tried dragging the pc to the hub and testing it there?
 
So I'm trying to connect an XP PC to a hub. The port on the hub is
good. The cable is new and a tester shows that it is good.
When I plug the cable into the PC it says the network cable is
unlplugged.
I wondered if the NIC could be bad, but when I plug it into my laptop,
I get the same message, even though I know my laptop network adapter
is working properly.
I'm not sure what to try next, other than a new cable, but I can't do
that easily, it's a very long run and through walls etc. And besides,
the cable tests good, so how could a different one be any better?
Any ideas?
Click to expand...


A more reliable way to diagnose the cabling:
Check the long cable electically:
At one end, disconnect a pair of wires and short their ends together.
From other end, use a multimeter to read for the short on the same
color pair, proving those two wires are good. If the short doesn't show
up on the right color pair it's either not a coninuous path or somethign
is miswired: Look for the short in the other pins to find a miswire. If
no other pair of any color combo show the short, then a wire is open.
Repeat for each pair of wires.

Likewise, now remove the short at the end, and check between each set of
wires for a short to any OTHER set of wires. In other words, make sure
there are no shorts. It's best to use a scale of around 1 K ohm for
this test in case the "short" turns out to be somethign wet from within
the wall or only semi-conductive or scraped insulation areas, etc..
Excessive pulling can break conductors and insulation both as it rounds
abrasive areas during the pull.

Recheck your pinouts on the cable to:
What the PC connector says it is and
What the hub says it is.
Do you need a straight thru or a crossover cable? This will tell you
for sure.
PC to hub can be different than hub to whatever in some cases.
I use a marker to mark the pin-1 side of each RJ45 - makes counting
easier.

Did you use CAT5 or 6 cable?
If you used regular phone cable, that could easily be your problem if
it's a very long run.
How long IS the run (in cable feet, not straight line)?
Depending, it may be that you need a repeater.
If there is a shield, is it connected or floating? It needs to be
grounded at the PC end for the line TO the hub.
You did use 8-pin connectors on the cabling, right?

OTOH:
Assuming the continuity test of the wire pairs all worked out OK:
If you suspect a problem somewhere in the in-wall cabling, it's a
lot easier to buy a separate spool of wire and externally connect it
from PC to hub to prove out whether it's the in-wall cabling bad or not;
especially if there are punch-downs of connectors along the way and
you've put cables in series.

If that makes sense to you, I think it should work it out for you.

Twayne
 
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