29 Sep
2004
29 Sep
'04
2:02 a.m.
On Sep 27 2004, 22:17, Tony Duell wrote:
1/2
> 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 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
29 Sep
29 Sep
2:10 a.m.
On Wed, 29 Sep 2004, Pete Turnbull wrote:
[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.
The third and fourth pairs would not be "so on". They'd be the pairs on
either side of the center, since Orange+White/Orange and Brown+White/Brown
are not split.
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
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8:23 a.m.
At 02:02 AM 9/29/2004, you wrote:
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.
I agree, and I suspect any straight-through RJ-45 cable
was for a telephone system, not networking. Perhaps
Sellam knows examples.
- John
2:16 a.m.
On Wed, 29 Sep 2004, John Foust wrote:
At 02:02 AM 9/29/2004, you wrote:
There were/are many uses for a straight-through 8-conductor cable with
RJ-45 connectors on each end. Lots of datacom equipment of old, old
telephone systems that used all 4 pairs, etc. Of course, these cables
would be used for the last few feet...the actual cable runs would have
twisted pairs.
Probably the biggest use for straight-through 8-conductor ribbon cable is
for serial communications.
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
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.
I agree, and I suspect any straight-through RJ-45 cable
was for a telephone system, not networking. Perhaps
Sellam knows examples. 
9:29 a.m.
On Sep 29, 2004, at 6:23 AM, John Foust wrote:
At 02:02 AM 9/29/2004, you wrote:
Oh, at that same job (novell) , I moved the network
to new quarters, Our jacks were wired with all 8
wires and I had "Y" jumpers that would let me connect
in the wire-closet one jack to two hubs, then in the
office I could use another Y cable to hook up two machines.
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.
I agree, and I suspect any straight-through RJ-45 cable
was for a telephone system, not networking. Perhaps
Sellam knows examples.
- John
10:38 a.m.
At 14:23 29/09/2004, John Foust wrote:
I agree, and I suspect any straight-through RJ-45
cable
was for a telephone system, not networking. Perhaps
Sellam knows examples.
I've encountered flat 8 core cable, terminated with RJ45's, used as patch
leads in a Serial environment. They were used with Baydek SMUX serial
boards, also seen them used with some Specialix terminal servers, both had
RJ45 sockets for the serial ports.
Of course, when one of my colleagues tried to use them for Ethernet we had
terrible problems. They would just about work (for the short lengths in a
patch cabinet) at 10Mbps, but were total no-no at 100Mbps.
Rob
3:37 a.m.
On Wed, 29 Sep 2004, Rob O'Donnell wrote:
At 14:23 29/09/2004, John Foust wrote:
You can use just about anything for short runs. Even 100-base-T might
work with 4-strands of random wire at some minimal distance. But if you
expect anything to run and run reliably, especially at a distance, use
properly rated cable :)
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
I agree, and I suspect any straight-through RJ-45
cable
was for a telephone system, not networking. Perhaps
Sellam knows examples.
I've encountered flat 8 core cable, terminated with RJ45's, used as patch
leads in a Serial environment. They were used with Baydek SMUX serial
boards, also seen them used with some Specialix terminal servers, both had
RJ45 sockets for the serial ports.
Of course, when one of my colleagues tried to use them for Ethernet we had
terrible problems. They would just about work (for the short lengths in a
patch cabinet) at 10Mbps, but were total no-no at 100Mbps. 
11:48 a.m.
On Wednesday 29 September 2004 03:37, Vintage Computer Festival wrote:
On Wed, 29 Sep 2004, Rob O'Donnell wrote:
Indeed, I have used 10ft piece of round phone cable (not UTP) with RJ45s
to run 100BaseT, and gotten a full 12MB/sec or so out of it. However,
"results may not be typical".
Pat
--
Purdue University ITAP/RCS --- http://www.itap.purdue.edu/rcs/
The Computer Refuge --- http://computer-refuge.org
At 14:23 29/09/2004, John Foust wrote:
You can use just about anything for short runs. Even 100-base-T
might work with 4-strands of random wire at some minimal distance.
But if you expect anything to run and run reliably, especially at a
distance, use properly rated cable :) I agree, and I suspect any straight-through RJ-45
cable
was for a telephone system, not networking. Perhaps
Sellam knows examples.
I've encountered flat 8 core cable, terminated with RJ45's, used as
patch leads in a Serial environment. They were used with Baydek
SMUX serial boards, also seen them used with some Specialix
terminal servers, both had RJ45 sockets for the serial ports.
Of course, when one of my colleagues tried to use them for Ethernet
we had terrible problems. They would just about work (for the
short lengths in a patch cabinet) at 10Mbps, but were total no-no
at 100Mbps.
1:30 p.m.
At 03:37 AM 9/29/2004, Vintage Computer Festival wrote:
You can use just about anything for short runs. Even
100-base-T might
work with 4-strands of random wire at some minimal distance. But if you
expect anything to run and run reliably, especially at a distance, use
properly rated cable :)
These days, though, it's getting harder: inexpensive consumer
networking gear is all over the map in terms of what sort of
signal degradation it can handle.
I've seen some equipment that can't pick up a signal on a 100-foot
run of suitably rated and crimped cable. I don't have a TDR tester,
but a simple $50 tester shows valid wiring.
- John
11:04 a.m.
I agree, and I
suspect any straight-through RJ-45 cable
was for a telephone system, not networking. Perhaps
Sellam knows examples.
I've encountered flat 8 core cable, terminated with RJ45's, used as patch
leads in a Serial environment. They were used with Baydek SMUX serial
boards, also seen them used with some Specialix terminal servers, both had
RJ45 sockets for the serial ports.
7395
days inactive
7395
days old
9 comments
7 participants
participants (7)
-
classiccmp.org＠irrelevant.fsnet.co.uk -
jfoust＠threedee.com -
pat＠computer-refuge.org -
patrick＠vintagecomputermarketplace.com -
pete＠dunnington.u-net.com -
ron.hudson＠sbcglobal.net -
vcf＠siconic.com