AS/400 9404 and TWINAX questions...

From: Pete Turnbull <>
Date: Wed Sep 29 02:02:46 2004

On Sep 27 2004, 22:17, Tony Duell wrote:
> > Good news: You could even make an Ethernet/Twinax single jack, if
> > not running faster than 100Mbps ethernet, as they run 1/2 & 3/6 for
> > 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
> > 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
> as a pair and 3/6 as another pair (I think the other 2 pairs were 4/5
> 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

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