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-   -   Cat 5e cables and networking (http://www.hardwarebanter.com/showthread.php?t=70080)

Opticreep April 6th 04 04:03 PM

Cat 5e cables and networking
 
I'm having a weird problem setting up my router.

I have a computer, a DSL modem, and a router.

If I hook them all up properly using a few short CAT5 cables,
everything works fine.

If I hook them all up using a few short CAT5 cables, and a 40-ft long
CAT5e cable between the PC and the router... the PC LAN card doesn't
acknowledge the connection.

My first guess was that the long CAT5e cable is faulty. But then, if
I ditch the router altogether, and hook up my DSL Modem directly to my
PC with the 40-ft CAT5e cable... everything works fine.

I don't get it. I can't figure out why the long CAT5e cable would
allow for a direct PC-to-modem connection, but not PC-to-router
connection.

William Tasso April 6th 04 06:49 PM

Opticreep wrote:
I'm having a weird problem setting up my router.

I have a computer, a DSL modem, and a router.

If I hook them all up properly using a few short CAT5 cables,
everything works fine.

If I hook them all up using a few short CAT5 cables, and a 40-ft long
CAT5e cable between the PC and the router... the PC LAN card doesn't
acknowledge the connection.

My first guess was that the long CAT5e cable is faulty. But then, if
I ditch the router altogether, and hook up my DSL Modem directly to my
PC with the 40-ft CAT5e cable... everything works fine.

I don't get it. I can't figure out why the long CAT5e cable would
allow for a direct PC-to-modem connection, but not PC-to-router
connection.


Does the 40ft cable have the same config as the shorter cable? In other
words: is one of them a cross-over cable?

Do the link lights come up?

Do you have a cable tester? What does it say?

Cross-over cables are evil.

--
William Tasso



Opticreep April 7th 04 01:30 AM

"William Tasso" wrote in message ...

Does the 40ft cable have the same config as the shorter cable? In other
words: is one of them a cross-over cable?


I don't think it's a cross-over cable. If it was, it wouldn't have
allowed connection between the DSL modem and the PC. The problem only
occurs if I use that same cable between the router and the PC.


Do the link lights come up?


The link lights come up, but it blinks all the time. My PC detects it
as "unplugged".


Do you have a cable tester? What does it say?


Sorry, I don't have a cable tester. I heard those things are
expensive. I only tested the cable by using it between the DSL modem
and PC, and it seemed fine.

jesus X April 7th 04 05:13 AM

On 4/6/2004 8:30 PM Opticreep cranked up the brainbox and said:
I don't think it's a cross-over cable. If it was, it wouldn't have
allowed connection between the DSL modem and the PC. The problem only
occurs if I use that same cable between the router and the PC.


Which means it's a crossover cable. If it worked directly between the two, then
it's crossover, and not straight through.

Cable testers can be as cheap as a buck for a couple parts, a LED and a battery.
You can get a decent one for just a few dollars.

--
jesus X [ Booze-fueled paragon of pointless cruelty and wanton sadism. ]
email [ jesus_x @ mozillanews.org ]
web [ http://www.mozillanews.org ]
insult [ As usual, you've been a real pantload. ]
warning [ Don't touch that! You might mutate your fingers. ]

glen herrmannsfeldt April 7th 04 09:31 AM

jesus X wrote:
On 4/6/2004 8:30 PM Opticreep cranked up the brainbox and said:


I don't think it's a cross-over cable. If it was, it wouldn't have
allowed connection between the DSL modem and the PC. The problem only
occurs if I use that same cable between the router and the PC.


Which means it's a crossover cable. If it worked directly between the two, then
it's crossover, and not straight through.


Cable testers can be as cheap as a buck for a couple parts, a LED and a battery.
You can get a decent one for just a few dollars.


As far as I know, DSL modems come both ways.

-- glen


Opticreep April 7th 04 11:00 AM

jesus X wrote in message ...
On 4/6/2004 8:30 PM Opticreep cranked up the brainbox and said:
I don't think it's a cross-over cable. If it was, it wouldn't have
allowed connection between the DSL modem and the PC. The problem only
occurs if I use that same cable between the router and the PC.


Which means it's a crossover cable. If it worked directly between the two, then
it's crossover, and not straight through.

Cable testers can be as cheap as a buck for a couple parts, a LED and a battery.
You can get a decent one for just a few dollars.



Huh?

I'd hate to sound so newbie-ish, but what makes you say that it's a
crossover cable? I use that cable between the DSL modem and my PC
(without the router). That means it's a straight-through, doesn't it?
I thought crossover cables were only used if I was connecting one
computer directly into another computer with nothing else in-between.

Emil Luca April 7th 04 03:27 PM

Look at the rj45 and see if the color of the cable connection inside the
rj45 is the same on both ends.
If it is different it is a crossover cable.



"Opticreep" wrote in message
m...
jesus X wrote in message

...
On 4/6/2004 8:30 PM Opticreep cranked up the brainbox and said:
I don't think it's a cross-over cable. If it was, it wouldn't have
allowed connection between the DSL modem and the PC. The problem only
occurs if I use that same cable between the router and the PC.


Which means it's a crossover cable. If it worked directly between the

two, then
it's crossover, and not straight through.

Cable testers can be as cheap as a buck for a couple parts, a LED and a

battery.
You can get a decent one for just a few dollars.



Huh?

I'd hate to sound so newbie-ish, but what makes you say that it's a
crossover cable? I use that cable between the DSL modem and my PC
(without the router). That means it's a straight-through, doesn't it?
I thought crossover cables were only used if I was connecting one
computer directly into another computer with nothing else in-between.




jesus X April 7th 04 10:01 PM

On 4/7/2004 6:00 AM Opticreep cranked up the brainbox and said:
I'd hate to sound so newbie-ish, but what makes you say that it's a
crossover cable? I use that cable between the DSL modem and my PC
(without the router). That means it's a straight-through, doesn't it?
I thought crossover cables were only used if I was connecting one
computer directly into another computer with nothing else in-between.


While Glen is right and there are DSL adapters that come both ways, most come
wired ready to be plugged into a hub/switch/router. Thus, if you can connect it
to a PC directly, it's most likely a crossover cable. As Emil said, check the
colors of the wiring in the cable ends.

--
jesus X [ Booze-fueled paragon of pointless cruelty and wanton sadism. ]
email [ jesus_x @ mozillanews.org ]
web [ http://www.mozillanews.org ]
insult [ As usual, you've been a real pantload. ]
warning [ Don't touch that! You might mutate your fingers. ]

Opticreep April 8th 04 12:47 AM

"Emil Luca" wrote in message om...
Look at the rj45 and see if the color of the cable connection inside the
rj45 is the same on both ends.
If it is different it is a crossover cable.


It's straight-through.

Although I may have a weird theory on why I'm having problems.
Apparently, my CAT5 cables weren't properly made. I noticed that pins
3 & 6 on the RJ45 didn't make a twisted pair. Instead, the techie who
installed the RJ45's for me made twisted pairs out of pins 3 & 4, and
then 5 & 6. This probably generated a lot of noise on signals going
through pins 3 and 6. I'm quite sure that category 5 standards state
that pins 3 & 6 make up a pair (and so does 4 & 5).

This oversight probably didn't affect my short 0.5 meter cables too
much. But on a 25-meter cable, the signal-to-noise ratio might have
become too high. At least that's my theory.

But that still doesn't make sense. I don't think the signal-to-noise
ratio should be affected so drastically from this one little mistake.
And besides, why would this 24-ft CAT5e cable work between a DSL
straight to my PC, but *not* work between a router and a PC? Maybe it
has to do with signal strength or the different impedences, but
thinking too much makes my head hurt.

Rick Wintjen April 8th 04 04:18 AM

Opticreep wrote:
"Emil Luca" wrote in message om...
Look at the rj45 and see if the color of the cable connection inside the
rj45 is the same on both ends.
If it is different it is a crossover cable.


It's straight-through.

Although I may have a weird theory on why I'm having problems.
Apparently, my CAT5 cables weren't properly made. I noticed that pins
3 & 6 on the RJ45 didn't make a twisted pair. Instead, the techie who
installed the RJ45's for me made twisted pairs out of pins 3 & 4, and
then 5 & 6. This probably generated a lot of noise on signals going
through pins 3 and 6. I'm quite sure that category 5 standards state
that pins 3 & 6 make up a pair (and so does 4 & 5).

This oversight probably didn't affect my short 0.5 meter cables too
much. But on a 25-meter cable, the signal-to-noise ratio might have
become too high. At least that's my theory.

But that still doesn't make sense. I don't think the signal-to-noise
ratio should be affected so drastically from this one little mistake.
And besides, why would this 24-ft CAT5e cable work between a DSL
straight to my PC, but *not* work between a router and a PC? Maybe it
has to do with signal strength or the different impedences, but
thinking too much makes my head hurt.

The router probably has a 10/100 interface, also your NIC, so they would
have tried to operate at 100T. The modem is almost certainly a 10T.
Mis-matched pairs are tolerated better at the lower speeds, but you may
have had data errors that weren't bad enough to get your attention.



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