On 30 Nov 2005 02:51:01 -0800,it is alleged that "jim_in_sussex"
spake thusly in uk.d-i-y:

[snippage]

You might get away with what you are suggesting, but it is bad
practice to mix services in one cable. It might not cause a problem
at 10Mbits, but if the link is set or negotiates to 100Mbit, then
there is a fair chance that the ethernet will run unreliably.

Understood - but it's going into my parents home & is only being
installed for convenience when visiting, not posterity. However given
what you say, What is the best choice of cable?

3 separate cables would be best.


requirements a

A) to take the unfiltered AB signal downstairs (about 25m) (all speech
telephone cables being filtered off at the entry point) - essential

B) Take a new speech telephone cable to near the router from the filter
point. - useful only

C). Bring back part way (to 1st floor) a CAT5 cable to carry ethernet
to/from the router. - high up in the wants.


For A) is CAT5 really needed? Won't ordinary telephone cable do?
After all the signal travels unfiltered 3/4mile or more from the
exchange on normal BT cable.

Ordinary telephone cable would be fine for both DSL and Voice signals
yes. It has the advantage of being slightly smaller than cat5.

For B) ordinary telephone cable will do, but if that is OK for A) & I
try to use the same (6 way) cable as for A then is there a risk of
cross-talk?

If you use all 3 wires required (Including the bell shunt) then yes,
crosstalk will likely become a problem (How much this would affect
ADSL I am not sure). Running the voice line as just A+B (2+5) and
using master sockets at the extension points would likely prevent any
potential problem, at the expense of causing bell tinkle should you
ever use a pulse dialling phone.


For C) clearly a dedicated CAT5 is what you're recommending - will do

There's something I don't understand here - why is CAT5 the standard
cable when apparently only half the cable is used (4 wires out of 8)?

In 100baseTX or 10baseT ethernet -which are the most common- this is
true, some variants of gigabit ethernet can operate across cat5 cable
using all 4 pairs however. It's considered good practise to connect
all 4 pairs, allowing future use with whatever standard is required.


Also what are the standard pairings on CAT5 for sthe standard PC router
ethernet signals?

Assuming the router uses EIA/TIA 568B (which is the most common)

white/orange = Transmit Data +
orange/white = Transmit Data -
white/green = Receive Data +
blue/white = Spare
white/blue = Spare
green/white = Receive Data -
white/brown = Spare
brown/white = Spare

--
Whenever people say "we mustn't be sentimental", you can take it
they are about to do something cruel. And if they add, "we must
be realistic", they mean they are going to make money out of it.
- Brigid Brophy