Odd network problem

I run a mixed wired / wireless network- several PCs to a switched hub. One
of the cables seems to have developed a fault. If any PC is connect to
the switched-hub via this cable, the OTHER PCs on the network display a
"network cable unplugged" warning, although the various activity LEDs still
indicate all is well. If the "bad" is cable left unconnected at the PC end,
the rest of the network works fine.

I've tried various configurations to confirm the fault is in the cable and
there seems little doubt.

Prior to this problem showing up, the network has worked fine for some time
(>1 year) without issue in this configuration.

The network is running normally after another temporary cable was laid in.

I will, when I have time, trace the cable run to find the fault but I am
curious if this symptom is a known one.

Note: Someone has pointed out the term "switched-hub" may be an misnomer. I
doubt calling the box the wrong name has caused this.


TIA

Brian




Brian Reay

"Brian Reay" <(E-Mail Removed)> wrote in message
news:lpPEi.38839$(E-Mail Removed)...
>I run a mixed wired / wireless network- several PCs to a switched hub. One
> of the cables seems to have developed a fault. If any PC is connect to
> the switched-hub via this cable, the OTHER PCs on the network display a
> "network cable unplugged" warning, although the various activity LEDs
> still
> indicate all is well. If the "bad" is cable left unconnected at the PC
> end,
> the rest of the network works fine.
>
> I've tried various configurations to confirm the fault is in the cable and
> there seems little doubt.

As part of your various configurations, have you tried the duff cable in a
different port on the hub?

It sounds a very odd symptom: that a problem with one cable can cause all
the other PCs to display "not connected". Does the PC on the dodgy cable
think it's connected and does that PC work OK on the network?

Brian Reay wrote:
> I run a mixed wired / wireless network- several PCs to a switched hub. One
> of the cables seems to have developed a fault. If any PC is connect to
> the switched-hub via this cable, the OTHER PCs on the network display a
> "network cable unplugged" warning, although the various activity LEDs still
> indicate all is well. If the "bad" is cable left unconnected at the PC end,
> the rest of the network works fine.
>
> I've tried various configurations to confirm the fault is in the cable and
> there seems little doubt.
>
> Prior to this problem showing up, the network has worked fine for some time
> (>1 year) without issue in this configuration.
>
> The network is running normally after another temporary cable was laid in.
>
> I will, when I have time, trace the cable run to find the fault but I am
> curious if this symptom is a known one.
>
> Note: Someone has pointed out the term "switched-hub" may be an misnomer. I
> doubt calling the box the wrong name has caused this.
>
>
> TIA
>
> Brian
>
>

If it's a switch, this seems very odd behaviour, as the connection
should be isolated from the other ports.

If it's a hub, then they are all "joined". One possibility is that the
pairs are mixed up. From a (limited) experience, most 10/100 NICs seem
to ground the unused pairs and crossed pairs could ground the hub TX
pair (computer RX pair), removing the signal from the other connected
systems. Does the computer connected to the "problem" cable display any
fault condition?

PeeGee
--
The reply address is a spam trap. All mail is reported as spam.
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knowledge or consent of the computer user. Software should also be able
to be removed from a computer easily."
Peter Cullen, Microsoft Chief Privacy Strategist (Computing 18 Aug 05)

"Mortimer" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> "Brian Reay" <(E-Mail Removed)> wrote in message
> news:lpPEi.38839$(E-Mail Removed)...
>>I run a mixed wired / wireless network- several PCs to a switched hub. One
>> of the cables seems to have developed a fault. If any PC is connect to
>> the switched-hub via this cable, the OTHER PCs on the network display a
>> "network cable unplugged" warning, although the various activity LEDs
>> still
>> indicate all is well. If the "bad" is cable left unconnected at the PC
>> end,
>> the rest of the network works fine.
>>
>> I've tried various configurations to confirm the fault is in the cable
>> and
>> there seems little doubt.
>
> As part of your various configurations, have you tried the duff cable in a
> different port on the hub?

Yes, and a different hub. Same symptoms.

> It sounds a very odd symptom: that a problem with one cable can cause all
> the other PCs to display "not connected". Does the PC on the dodgy cable
> think it's connected and does that PC work OK on the network?

I don't recall.

--
73
Brian, G8OSN
www.g8osn.org.uk

"PeeGee" <(E-Mail Removed)> wrote in message
news:fc0inc$t8c$(E-Mail Removed)...
> If it's a hub, then they are all "joined". One possibility is that the
> pairs are mixed up. From a (limited) experience, most 10/100 NICs seem to
> ground the unused pairs and crossed pairs could ground the hub TX pair
> (computer RX pair), removing the signal from the other connected systems.
> Does the computer connected to the "problem" cable display any fault
> condition?

I must admit, I don't recall if the PC normaly on the rogue cable showed a
"no network cable" type of fault.

Brian

In article <lpPEi.38839$(E-Mail Removed)>, Brian Reay
says...

> I will, when I have time, trace the cable run to find the fault

Why bother? At pennies for the plugs and cable being dirt cheap,
there's really no point.


--
Conor

I'm not prejudiced. I hate everyone equally.

"Conor" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> In article <lpPEi.38839$(E-Mail Removed)>, Brian Reay
> says...
>
>> I will, when I have time, trace the cable run to find the fault
>
> Why bother? At pennies for the plugs and cable being dirt cheap,
> there's really no point.

Because I'd like to understand the problem.

Brian

"Brian Reay" <(E-Mail Removed)> wrote:

>
>"Conor" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed)...
>> In article <lpPEi.38839$(E-Mail Removed)>, Brian Reay
>> says...
>>
>>> I will, when I have time, trace the cable run to find the fault
>>
>> Why bother? At pennies for the plugs and cable being dirt cheap,
>> there's really no point.
>
>Because I'd like to understand the problem.
>

Fair enough, but surely the problem is that the cable is duff. If replacing it cures
the problem then you've proved the cable to be at fault. Once you know the cable is
at fault, you can then work out how the problem occurred in the first place.

Next step - and IMHO an important one is to find *why* the cable became faulty if
that is the case.

Was it a one off, (ie a slightly poor crimp in one of the wires in a plug so that the
wire became disconnected over time or through movement of the cable), or was a
problem that might re-occur after the cable is replaced (wear on the cable passing
under a carpet, possible damage caused by pets chewing, damp ingress* etc etc)?

As Conor said, sometimes just fixing something that is quick and easy is the best
solution - there are too many other things that can go wrong to worry about minor
irritations. OTOH is the replacement cable also goes wrong then other factors need to
be considered.

HTH

* is this really a word??











--

Andrew Sayers

In article <SfeFi.2400$(E-Mail Removed)>, Brian Reay
says...
>
> "Conor" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > In article <lpPEi.38839$(E-Mail Removed)>, Brian Reay
> > says...
> >
> >> I will, when I have time, trace the cable run to find the fault
> >
> > Why bother? At pennies for the plugs and cable being dirt cheap,
> > there's really no point.
>
> Because I'd like to understand the problem.

You already do. It's bits of wires. The only two possibilities are a
break in the wire and a dodgy crimp on the plug.

Sure trace it if it's a long run hidden away where replacing the full
length requires major building work so you cut'n'patch if possible but
if it's a patch lead running from 'puter to router and you can unplug
it and swap one in, there's no point.


--
Conor

I'm not prejudiced. I hate everyone equally.

In message <(E-Mail Removed)>, Conor
<(E-Mail Removed)> writes
>You already do. It's bits of wires. The only two possibilities are a
>break in the wire and a dodgy crimp on the plug.
Umm, you missed out short circuits, I'm kind of interested what would
cause the problem but definitely not enough to be bothered trying to
replicate the problem. As you say, it's cheap enough to replace that it
really doesn't matter unless it re-occurs.

--
Clint Sharp