On Sep 27 2004, 22:17, Tony Duell wrote:
> > Good news: You could even make an Ethernet/Twinax single jack, if
you're
> > not running faster than 100Mbps ethernet, as they run 1/2 & 3/6 for
their
> > pairs -- just use 4/5 for twinax.
> >
> > Bad news: *Most* pre-built cables don't follow the standard as to
where the
> > twisted pairs should be - most just go 1/2 - 3/4 - 5/6 - 7/8 - and
that's
> > bad for both Ethernet & twinax. You'll wanna punch down and/or
build your
> > own cables if you're going to do this.
>
> What?!?!?
>
> I've made the odd 10baseT patch lead, and I was always careful to get
1/2
> as a pair and 3/6 as another pair (I think the other 2 pairs were 4/5
and
> 7/8, but it;s been a long time..) Fiddling the wires into the RJ45
was a
> pain, but I assumed it was necessary....
>
> And you're telling me commercial cables get it wrong.
I've hardly ever seen a commercial standard Cat3 / Cat4 / Cat5 /Cat5e
cable that was miswired with split pairs. Telephone cables wired to
the old USOC standard are different[1], but not usually fitted with
RJ45 plugs, and flat cables are obviously not twisted pairs. Tony, I
wouldn't have any qualms about buying commercial cables. If you do
want to wire your own, the standard order (for TIA568B, which is the
most common scheme) is white+orange, orange, white+green, blue,
white+blue, green, white+brown, brown.
[1] They're not paired as 1+2, 3+4, etc either. The first pair is the
centre pins, the second pair is the two pins either side of centre, and
so on, working outwards.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Wed Sep 29 2004 - 02:02:46 BST