A network cable is unplugged?? No it isn't!

Network Problems

Ok, I have two PCs running on Windows XP linked directly with a crossover
cable by two Ethernet cards. Until recently the network was fine, internet
connection sharing was working great, files could be transferred,
everything. Then things just stopped working. Nothing had been changed in
the setup.

What happens now is that Windows XP, on both PCs, says 'A network cable is
unplugged'. The indicator lights on the network card don't light up anymore
either. I can't even connect to the other PC on the network, let alone see
it through mine.

I've tried -

1. Re-installing network cards.
2. Changing network cards.
3. New crossover cable.

Yet I am STILL told that a cable is unplugged. Windows says the network
cards at both ends are installed correctly and working. So Im baffled, what
on Earth could be the problem?

Thanks

Jamie

--
-
I know the wheels go round and round, but whats the story prior to that
movement?

On Tue, 18 May 2004 19:51:28 +0100, Jamie_Manic wrote:

>
> Network Problems
>
> Ok, I have two PCs running on Windows XP linked directly with a crossover
> cable by two Ethernet cards. Until recently the network was fine, internet
> connection sharing was working great, files could be transferred,
> everything. Then things just stopped working. Nothing had been changed in
> the setup.
>
> What happens now is that Windows XP, on both PCs, says 'A network cable is
> unplugged'. The indicator lights on the network card don't light up anymore
> either. I can't even connect to the other PC on the network, let alone see
> it through mine.
>
> I've tried -
>
> 1. Re-installing network cards.
> 2. Changing network cards.
> 3. New crossover cable.
>
> Yet I am STILL told that a cable is unplugged. Windows says the network
> cards at both ends are installed correctly and working. So Im baffled, what
> on Earth could be the problem?
>
> Thanks
>
> Jamie

Funnily enough network cards don't normally like working back to back. The
reason for this is they need to see a signal on the cable when they are
powered up so they can negociate the neteork speed and simplex/duplex
settings. The best bet is buy a hub/switch, usually less than 20 UK pound.

If you really want to use them like this, try disconnecting the mains from
both computers then switch on and start again (soft power down does not
always de-power the network card) You may have to do this a few times, try
repowering the computes in diferent orders.

Hope this helps, Graham

Jamie_Manic wrote:
> Network Problems
>
> Ok, I have two PCs running on Windows XP linked directly with a
> crossover cable by two Ethernet cards. Until recently the network was
> fine, internet connection sharing was working great, files could be
> transferred, everything. Then things just stopped working. Nothing
> had been changed in the setup.
>
> What happens now is that Windows XP, on both PCs, says 'A network
> cable is unplugged'. The indicator lights on the network card don't
> light up anymore either. I can't even connect to the other PC on the
> network, let alone see it through mine.
>
> I've tried -
>
> 1. Re-installing network cards.
> 2. Changing network cards.
> 3. New crossover cable.
>
> Yet I am STILL told that a cable is unplugged. Windows says the
> network cards at both ends are installed correctly and working. So Im
> baffled, what on Earth could be the problem?
>
Link speeds set to 10 on one machine and 100 on the other?
--
Alex

"We are now up against live, hostile targets"

"So, if Little Red Riding Hood should show up with a bazooka and a bad
attitude, I expect you to chin the bitch! "

www.drzoidberg.co.uk
www.upce.org.uk

"Graham" <(E-Mail Removed)> wrote in message
news(E-Mail Removed)...
> On Tue, 18 May 2004 19:51:28 +0100, Jamie_Manic wrote:
>
> >
> > Network Problems
> >
> > Ok, I have two PCs running on Windows XP linked directly with a
crossover
> > cable by two Ethernet cards. Until recently the network was fine,
internet
> > connection sharing was working great, files could be transferred,
> > everything. Then things just stopped working. Nothing had been changed
in
> > the setup.
> >
> > What happens now is that Windows XP, on both PCs, says 'A network cable
is
> > unplugged'. The indicator lights on the network card don't light up
anymore
> > either. I can't even connect to the other PC on the network, let alone
see
> > it through mine.
> >
> > I've tried -
> >
> > 1. Re-installing network cards.
> > 2. Changing network cards.
> > 3. New crossover cable.
> >
> > Yet I am STILL told that a cable is unplugged. Windows says the network
> > cards at both ends are installed correctly and working. So Im baffled,
what
> > on Earth could be the problem?
> >
> > Thanks
> >
> > Jamie
>
> Funnily enough network cards don't normally like working back to back. The
> reason for this is they need to see a signal on the cable when they are
> powered up so they can negociate the neteork speed and simplex/duplex
> settings. The best bet is buy a hub/switch, usually less than 20 UK pound.
>
> If you really want to use them like this, try disconnecting the mains from
> both computers then switch on and start again (soft power down does not
> always de-power the network card) You may have to do this a few times, try
> repowering the computes in diferent orders.

I've never found that there's a problem connecting two PCs directly by
crossover cable. If I boot up one while the cable is unplugged from the
other (or if the other is switched off), then the "network cable is
unplugged" message always goes away when the second PC is plugged in or
switched on - I've never found this not to be the case. This is with Linksys
cards in both machines: maybe some cards are more sensitive than others.

But the really significant fact is that it used to work perfectly and
suddenly stopped, apparently (apparently!) without making any changes to the
OS or hardware, and that you've changed the cards and cable to eliminate
hardware faults.

Are you able to try connecting one/both to a hub to check whether the cards
can "see" that?

On Wed, 19 May 2004 07:28:29 +0100, in uk.comp.home-networking Graham
<(E-Mail Removed)> strung together this:

>Funnily enough network cards don't normally like working back to back. The
>reason for this is they need to see a signal on the cable when they are
>powered up so they can negociate the neteork speed and simplex/duplex
>settings. The best bet is buy a hub/switch, usually less than 20 UK pound.
>
Total bollocks. Two cards connected with a crossover cable will work
perfectly well. (Well, as perfectly well as networks work)!

The problem lies in the setup of the cards, could be the speed, the
duplexing, or it could even be that one or the other is disabled.
--

SJW
A.C.S. Ltd.

On Wed, 19 May 2004 08:21:59 +0000, Martin Underwood wrote:

> "Graham" <(E-Mail Removed)> wrote in message
> news(E-Mail Removed)...
>> On Tue, 18 May 2004 19:51:28 +0100, Jamie_Manic wrote:
>>
>> >
>> > Network Problems
>> >
>> > Ok, I have two PCs running on Windows XP linked directly with a
> crossover
>> > cable by two Ethernet cards. Until recently the network was fine,
> internet
>> > connection sharing was working great, files could be transferred,
>> > everything. Then things just stopped working. Nothing had been changed
> in
>> > the setup.
>> >
>> > What happens now is that Windows XP, on both PCs, says 'A network cable
> is
>> > unplugged'. The indicator lights on the network card don't light up
> anymore
>> > either. I can't even connect to the other PC on the network, let alone
> see
>> > it through mine.
>> >
>> > I've tried -
>> >
>> > 1. Re-installing network cards.
>> > 2. Changing network cards.
>> > 3. New crossover cable.
>> >
>> > Yet I am STILL told that a cable is unplugged. Windows says the network
>> > cards at both ends are installed correctly and working. So Im baffled,
> what
>> > on Earth could be the problem?
>> >
>> > Thanks
>> >
>> > Jamie
>>
>> Funnily enough network cards don't normally like working back to back. The
>> reason for this is they need to see a signal on the cable when they are
>> powered up so they can negociate the neteork speed and simplex/duplex
>> settings. The best bet is buy a hub/switch, usually less than 20 UK pound.
>>
>> If you really want to use them like this, try disconnecting the mains from
>> both computers then switch on and start again (soft power down does not
>> always de-power the network card) You may have to do this a few times, try
>> repowering the computes in diferent orders.
>
> I've never found that there's a problem connecting two PCs directly by
> crossover cable. If I boot up one while the cable is unplugged from the
> other (or if the other is switched off), then the "network cable is
> unplugged" message always goes away when the second PC is plugged in or
> switched on - I've never found this not to be the case. This is with Linksys
> cards in both machines: maybe some cards are more sensitive than others.
>
> But the really significant fact is that it used to work perfectly and
> suddenly stopped, apparently (apparently!) without making any changes to the
> OS or hardware, and that you've changed the cards and cable to eliminate
> hardware faults.
>
> Are you able to try connecting one/both to a hub to check whether the cards
> can "see" that?


Some cards are more amenable than others. Most modern cards are fully
automatic, the windows drivers will not allow tweaking. Some cards will
adapt to line conditions on the fly, these are the ones that don't mind
working back to back, they will deal with the line signal if and when it
arrives. Others won't. They need to see a signal on the line at power up.
If they don't they simply won't work. It would seem that at least one of
your network cards falls into this category.

Graham,

"Dr Zoidberg" <AlexNOOOO!!!!@drzoidberg.co.uk> wrote in message
news:(E-Mail Removed)...
> Jamie_Manic wrote:
> > Network Problems
> >
> > Ok, I have two PCs running on Windows XP linked directly with a
> > crossover cable by two Ethernet cards. Until recently the network was
> > fine, internet connection sharing was working great, files could be
> > transferred, everything. Then things just stopped working. Nothing
> > had been changed in the setup.
> >
> > What happens now is that Windows XP, on both PCs, says 'A network
> > cable is unplugged'. The indicator lights on the network card don't
> > light up anymore either. I can't even connect to the other PC on the
> > network, let alone see it through mine.
> >
> > I've tried -
> >
> > 1. Re-installing network cards.
> > 2. Changing network cards.
> > 3. New crossover cable.
> >
> > Yet I am STILL told that a cable is unplugged. Windows says the
> > network cards at both ends are installed correctly and working. So Im
> > baffled, what on Earth could be the problem?
> >
> Link speeds set to 10 on one machine and 100 on the other?
> --
> Alex
>

Agree - check the Network card at each side. Try setting the Speed and
Duplex to the same at each side (rather than leaving in "auto"), and make
sure they are in the enabled state.

Something we see a lot, is intermittant success of auto-negotiation (in a
large Enterprise network - 6000+ ports). Sometimes no connection, other
times massive error counts on switch ports. We ended up fixing the port
parameters at both the Workstation and the Switch. No more problems.

The Auto-negotiation spec is like a lot of rapidly developed, industry
driven (rather than forum/committee/etc) standards - it's so wide that two
vendors who could validly claim to meet the spec., might not work to each
other. Fixing speed and duplex is less flexible, but some would argue that
it means that us network guys are still in control of what the attached
devices are doing, capacity-wise....

Jamie_Manic wrote:
> What happens now is that Windows XP, on both PCs, says 'A network cable is
> unplugged'. The indicator lights on the network card don't light up anymore
> either. I can't even connect to the other PC on the network, let alone see
> it through mine.

A few friends and I had exactly the same problem setting up a home
network for someone. Everything appeared to be correct - the connections
to the switch were fine, Windows was configured correctly on all
machines and yet it still said there was a network cable unplugged.
Finally the only conclusion we could come to was that the cable was
dodgy. This may be the case.

-Nick Griffiths

True. I've had trouble with some homemade cables in the past.

If you (or a friend) has a RJ45 crimper tool, try crimping it down tightly
again and see if it makes a difference


"Nick Griffiths" <(E-Mail Removed)> wrote in message
news:c8i1l2$g3r$(E-Mail Removed)...
> Jamie_Manic wrote:
> > What happens now is that Windows XP, on both PCs, says 'A network cable
is
> > unplugged'. The indicator lights on the network card don't light up
anymore
> > either. I can't even connect to the other PC on the network, let alone
see
> > it through mine.
>
> A few friends and I had exactly the same problem setting up a home
> network for someone. Everything appeared to be correct - the connections
> to the switch were fine, Windows was configured correctly on all
> machines and yet it still said there was a network cable unplugged.
> Finally the only conclusion we could come to was that the cable was
> dodgy. This may be the case.
>
> -Nick Griffiths


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