Re: Munched network cable

In message <84928e8e4f.harriet@xxxxxxxxxx>
Harriet Bazley <bazley@xxxxxxxxxxxxxxxxx> wrote:

On 10 Apr 2008 as I do recall,
Brian Carroll wrote:

In article <1d7f838d4f.harriet@xxxxxxxxxx>, Harriet Bazley
<bazley@xxxxxxxxxxxxxxxxx> wrote:
Our networking currently has a hole in it - that is, to be
precise, two neatly-nibbled holes about two inches apart...

Nibbled by mice?

Pet rats (caught them at it - a second or so too late, alas). They
severed one wire each of two twisted pairs, the result of which is that
this computer can *see* the other end of the network, but can't actually
send or receive anything.

This means that one of the important pairs is intact, the other
broken.

10MBit and 100MBit use the 3+6 pair and the 1+2 pair.


Is it possible simply <FX: hollow laugh> to snip out the
damaged section, where one wire each of the four twisted pairs
has been severed, and solder together the resulting ends?
There's plenty of slack, since the cable is about eight feet
longer than it needs to be.

Yes it is possible, but the other alternatives suggested here
would make a better job. If you go to any PC computer small
shop you should be able to buy a new 'patch lead' for under a
fiver. You may need a 'crossover' cable -- you don't give much
detail of your setup.

That rings a bell. I believe it *was* a crossover cable; I don't
really know. I just explained the situation to CJE (Iyonix Aria=no disc
drive) and they sold us an RPC network card and a cable to plug between
the two computers. I suspect the networking only ever operates at a
relatively slow speed, since the other end is an RPC600.

The bit-rate used on the cable will be negotiated between the network
cards, and will end up either 100MBit or 10MBit. The throughput will
be reduced by the performance of the host systems. In some cases
(ShareFS between dissimilar hosts) performance improves if the bitrate
is forced to 10MBit. It was because of an effect once described as
"like drinking from a firehose".

The problem as I understand it with a 'patch lead' is that I would still
need some means of attaching it to the severed ends.

A patch cable is a cable with two plugs, used to patch computers to
switches (as in "patch panel", not patch as in repair).

A crossover cable has the 1+2 and 3+6 pairs swapped at one end, so can
be used to connect two computers. Switches normally have the pairs
already swapped, so for them you use a straight or patch cable. (When
linking switches you should also use a crossed cable.) As most
switches are also capable of automatically swapping the pairs, you can
usually use a "wrong" cable with a switch as well.


Trying to borrow
and/or Freecycle a crimp tool sounds like the best suggestion.
Heatshrink sleeving also sounds like a good idea - I'd never heard of
that.

If you are really stuck email me (see
below) and I may be able to send you a suitable cable.

But it /is/ possible to repair by reconnecting the wires. You
should expose say 8" of the inner twisted pairs, then untwist
one pair at a time, resolder the broken wire, fold up the
unbroken wire to match the length of the repaired one, then tape
up all 8 wires at that point to cover the repair. Repeat this
at intevals of 2" for the other 3 twisted pairs. Test for
continuity, pin to pin, of the whole cable (watch if using a
crossover cable), then finally tape over the whole repaired
length. Dont worry too much if there is an outer screen;

There's no screening (that would probably have deterred the nibblers!),
just a plastic outer sleeve.



--
Alan Adams, from Northamptonshire
alan.adams@xxxxxxxxxxxxxxxxxxxxxxxxxxx
http://www.nckc.org.uk/
.

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