| Author |
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Jimmythekey
Guest
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 Posted:
Wed Dec 08, 2004 5:16 am Post subject:
Crossover cable, not working (Kind of) |
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Hi,
I've recently made a crossover cable(30m) to connect between 2 laptops.
I can't get it to work.
I have an IBM thinkpad, and my friend has a toshiba something or other.
As far as I can see both NIC's are installed correctly with file and
print sharing enabled etc.
Here is the strange part, I brought the cable into work to test it, I
connected a desktop PC to one of the workers laptops and got a FULLY
functional connection, with pinging and file transfer successful. So
now I thought one of the NIC's in one of the laptops was faulty. I
brought my laptop into work and low and behold I can't get a connection
between my laptop and my desktop PC.
However, I connected the patch cable from the office into my laptop NIC
and all of a sudden I have fully functional network access.
So here is the overview.
1. Crossover between myself and my friends laptops (FAILURE)
2. Crossover between computer desktop and work laptop (SUCCESS)
3. Crossover between computer desktop and my laptop (FAILURE)
4. Patch cable from work network into my laptop (SUCCESS)
What the hell is going on ?
My thinkpad is a 1999. Is there a possibility that my workmates new
laptop is able to detect a bad crossover cable wiring and re-transmit
the signals on different pairs to get a successful network connection ?
Confused,
Ronan Walsh. |
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Robert Redelmeier
Guest
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| Posted:
Wed Dec 08, 2004 6:08 am Post subject:
Re: Crossover cable, not working (Kind of) |
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Jimmythekey <walshr@esatclear.ie> wrote:
| Quote: | 1. Crossover between myself and my friends laptops (FAILURE)
2. Crossover between computer desktop and work laptop (SUCCESS)
3. Crossover between computer desktop and my laptop (FAILURE)
4. Patch cable from work network into my laptop (SUCCESS)
My thinkpad is a 1999. Is there a possibility that my
workmates new laptop is able to detect a bad crossover cable
wiring and re-transmit the signals on different pairs to
get a successful network connection ? Confused,
|
Yes, it is confusing. If the workmates new laptop has gigabit,
there's an excellent chance it has auto-MDI and can correct
for crossover. You may well have a straight patch cable.
Check by looking carefully through the plastic at pin 2 (2nd from
left, tab down, plug pointing away) on both ends. It should
be different for a proper crossover cable (orange vs green).
If you have two oranges, you have a regular patch cable.
-- Robert |
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Jimmythekey
Guest
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| Posted:
Wed Dec 08, 2004 6:34 am Post subject:
Re: Crossover cable, not working (Kind of) |
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I don't think it's a patch cable, but the cable might be faulty (might
have followed a dodgy diagram). I'm re-crimping it now, so I'll see
how that goes.
Thanks.
Ronan. |
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Jimmythekey
Guest
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| Posted:
Wed Dec 08, 2004 6:38 am Post subject:
Re: Crossover cable, not working (Kind of) |
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I don't think it's a patch cable, but the cable might be faulty (might
have followed a dodgy diagram). I'm re-crimping it now, so I'll see
how that goes.
Thanks.
Ronan. |
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Jimmythekey
Guest
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| Posted:
Wed Dec 08, 2004 11:25 am Post subject:
Re: Crossover cable, not working (Kind of) |
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Ok guys, here is where it gets weird.
I got a small patch lead (Straight through) and connected it from my
desktop computer straight to my laptop. I got a connection and could
ping. Is that not a bit weird to anyone else ?
I then thought, I'll just re-wire my crossover cable to a patch lead
and I'll be sorted ! However, I re-wired my 30m crossover cable to a
30m patch and when I connected NOTHING happens. Damn this is annoying
me. I even got a multi-meter and checked pin for pin that they were
all getting a signal.
I don't think it's the length of the cable as it did work when
connected from desktop computer to another work laptop.
This is really confusing ... help.
Ronan. |
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James Knott
Guest
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| Posted:
Wed Dec 08, 2004 5:55 pm Post subject:
Re: Crossover cable, not working (Kind of) |
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Jimmythekey wrote:
| Quote: | My thinkpad is a 1999. Is there a possibility that my workmates new
laptop is able to detect a bad crossover cable wiring and re-transmit
the signals on different pairs to get a successful network connection ?
Confused,
|
My first bet, would be the cable. Get another one and see if it works. Did
you wire it correctly? Check EIA/TIA 568A or B for details. |
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James Knott
Guest
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| Posted:
Wed Dec 08, 2004 5:57 pm Post subject:
Re: Crossover cable, not working (Kind of) |
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Jimmythekey wrote:
| Quote: | I then thought, I'll just re-wire my crossover cable to a patch lead
and I'll be sorted ! However, I re-wired my 30m crossover cable to a
30m patch and when I connected NOTHING happens. Damn this is annoying
me. I even got a multi-meter and checked pin for pin that they were
all getting a signal.
I don't think it's the length of the cable as it did work when
connected from desktop computer to another work laptop.
This is really confusing ... help.
|
More than likely you've got a mis-wired cable. Check to make sure it's
wired to spec. |
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Robert Redelmeier
Guest
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| Posted:
Wed Dec 08, 2004 7:35 pm Post subject:
Re: Crossover cable, not working (Kind of) |
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Jimmythekey <walshr@esatclear.ie> wrote:
| Quote: | I'm re-crimping it now, so I'll see how that goes.
|
Egads! T-568A or T-568B? What do you consider a "crossover"?
If you don't know what that question means, it is vastly
improbable that you can make a cable without split pairs.
Such a faulty cable might work over short distances, but will
not over long distances even though you will get link lights.
There are 40,320 ways of wiring a cable "straight-thru".
Only 1,152 work for 10/100. 384 for gigabit. None are
intuitive. Only two are standards.
Beware of newbies with crimpers. Even pros normally buy.
-- Robert |
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Jimmythekey
Guest
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Robert Redelmeier
Guest
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| Posted:
Thu Dec 09, 2004 3:44 am Post subject:
Re: Crossover cable, not working (Kind of) |
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Jimmythekey <walshr@esatclear.ie> wrote:
| Quote: | http://www.homenethelp.com/web/explain/about-ethernet-crossover.asp
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This is correct if you read carefully and look at the
diagrams very closely and realize the plug tab is down.
Also, you need to make sure you are using the correct plugs
for your cable type (stranded vs solid). Then you have to
crimp with the correct force.
-- Robert |
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Jeff Liebermann
Guest
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| Posted:
Thu Dec 09, 2004 7:07 am Post subject:
Re: Crossover cable, not working (Kind of) |
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On 8 Dec 2004 13:51:11 -0800, "Jimmythekey" <walshr@esatclear.ie>
wrote:
What diagram?
Here's how I do it. Colors are body-stripe. If you're looking
down at the gold connectors imbedded in the RJ-45 connector with the
cable in your hand, pin 1 is on the left (or just look at a factory
made EIA-568B cable).
EIA-568B Cross Over end
white-orange (1) (1) white-green
orange-white (2) C (2) green-white
white-green (3) A (3) white-orange
blue-white (4) B (4) white-brown
white-blue (5) L (5) brown
green-white (6) E (6) orange
white-brown (7) (7) blue
brown-white (8) (8) white-blue
The left side is standard official politically correct EIA-568B color
coding. The right side is all 4 pairs crossed over. Many cross over
cables only cross two pairs leaving the other two straight through.
That's fine for 10baseT and 100baseTX, but does NOT work with
1000baseTX, which uses all 4 pairs.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# jeffl@comix.santa-cruz.ca.us
# 831.421.6491 digital_pager jeffl@cruzio.com AE6KS |
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Justin Time
Guest
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| Posted:
Thu Dec 09, 2004 7:37 pm Post subject:
Re: Crossover cable, not working (Kind of) |
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Jeff Liebermann wrote:
| Quote: | On 8 Dec 2004 13:51:11 -0800, "Jimmythekey" <walshr@esatclear.ie
wrote:
I used this page
http://www.homenethelp.com/web/explain/about-ethernet-crossover.asp
as the source of my diagram.
What diagram?
Here's how I do it. Colors are body-stripe. If you're looking
down at the gold connectors imbedded in the RJ-45 connector with the
cable in your hand, pin 1 is on the left (or just look at a factory
made EIA-568B cable).
EIA-568B Cross Over end
white-orange (1) (1) white-green
orange-white (2) C (2) green-white
white-green (3) A (3) white-orange
blue-white (4) B (4) white-brown
white-blue (5) L (5) brown
green-white (6) E (6) orange
white-brown (7) (7) blue
brown-white (8) (8) white-blue
The left side is standard official politically correct EIA-568B color
coding. The right side is all 4 pairs crossed over. Many cross over
cables only cross two pairs leaving the other two straight through.
That's fine for 10baseT and 100baseTX, but does NOT work with
1000baseTX, which uses all 4 pairs.
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Justin Time
Guest
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| Posted:
Fri Dec 10, 2004 2:54 am Post subject:
Re: Crossover cable, not working (Kind of) |
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I must be missing something here. Google is not doing a very good job
of posting the comments to a message.
My response was to use the ABSOLUTE best way to create a cross-over as
posted by John Lundgren a couple of years back. It takes a few parts,
but it never fails.
Take a short piece of cable, two jacks, a surface mount box and a
permanent marker. Wire one of the jacks to the T568A pattern, the
other to the T568B pattern. Place the two jacks in the surface mount
box and then mark the box with a large X on the top. Use two standard
patch cords. There never is the problem of not knowing if you have a
standard or cross-over patch cord.
Rodgers Platt |
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James Knott
Guest
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| Posted:
Fri Dec 10, 2004 8:23 am Post subject:
Re: Crossover cable, not working (Kind of) |
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Justin Time wrote:
| Quote: | Take a short piece of cable, two jacks, a surface mount box and a
permanent marker. Wire one of the jacks to the T568A pattern, the
other to the T568B pattern. Place the two jacks in the surface mount
box and then mark the box with a large X on the top. Use two standard
patch cords. There never is the problem of not knowing if you have a
standard or cross-over patch cord.
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What I did, was take a cheap ($2) line coupler, and rewire it to be a
crossover. Works fine so far. |
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Al Dykes
Guest
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| Posted:
Fri Dec 10, 2004 8:37 am Post subject:
Re: Crossover cable, not working (Kind of) |
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In article <CsCdnfpXtv9RiyTcRVn-uA@rogers.com>,
James Knott <james.knott@rogers.com> wrote:
| Quote: | Justin Time wrote:
Take a short piece of cable, two jacks, a surface mount box and a
permanent marker. Wire one of the jacks to the T568A pattern, the
other to the T568B pattern. Place the two jacks in the surface mount
box and then mark the box with a large X on the top. Use two standard
patch cords. There never is the problem of not knowing if you have a
standard or cross-over patch cord.
What I did, was take a cheap ($2) line coupler, and rewire it to be a
crossover. Works fine so far.
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I carry a 2 ft xover cable and a CAT5 coupler in the tool bag. (I
reserve red color for them.) With that I can make any CAT 5
connection, anywhere an Xover, or prove that an existing cable is or
is not xover.
When I find a permenant cable that is wired xover I have the urge to
chop the ends off.
--
a d y k e s @ p a n i x . c o m
---- |
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