A Broadband and ADSL forum. BroadbanterBanter

Welcome to BroadbanterBanter.

You are currently viewing as a guest which gives you limited access to view most discussions and other FREE features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload your own photos and access many other special features. Registration is fast, simple and absolutely free so please, join our community today.

Go Back   Home » BroadbanterBanter forum » Newsgroup Discussions » uk.comp.home-networking (UK home networking)
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

uk.comp.home-networking (UK home networking) (uk.comp.home-networking) Discussion of all aspects of computer networking in the home, regardless of the platforms, software, topologies and protocols used. Examples of topics include recommendations for hardware or suppliers (e.g. NICs and cabling), protocols, servers, and specific network software. Advertising is not allowed.

Idle question



 
 
Thread Tools Display Modes
  #1  
Old March 15th 08, 07:16 PM posted to uk.comp.home-networking
Dave J.
external usenet poster
 
Posts: 139
Default Idle question

Can anyone offer an explanation for the ages-back decision to use two
different pin alignments for CAT-5/RJ45 networking plugs/sockets? You know
the way you need a crossover when the alignments are identical and a
straight through when they're mirrored?

Could it have been as simple as someone just imagining that all cables
would be straight-throughs because no one would deviate from the standard
pattern of router-[switch/hub]-Host?

I still remember my CCNA tutor having to stop and think when I pointed out
that if all sockets had the same pinout and all cables were crossovers
then there'd never be any problem..

On further thought, I can see that even under my supposed 'common sense'
approach, you'd still sometimes want straight-throughs for extension
purposes. Hmm, actually, no, you wouldn't would you, just make the inline
connectors also all crossover. So an extended link would be
[crossover-cable]-[crossover-inline]-[crossover-cable] and it would still
work perfectly.

So, what was the thinking? Does anyone have an idea?

Dave J.


--
Freeware Open Source Internet Television / Video RSS player. Fetches Video
RSS feeds or retrieves from regular searches on Youtube or Google video.
Dozens of feeds as defaults. Science, Politics, Music, Geekery...
Miro - Downloadable from http://www.GetMiro.org - Worth a try!
  #2  
Old March 16th 08, 12:58 PM posted to uk.comp.home-networking
PeeGee
external usenet poster
 
Posts: 311
Default Idle question

Dave J. wrote:
Can anyone offer an explanation for the ages-back decision to use two
different pin alignments for CAT-5/RJ45 networking plugs/sockets? You know
the way you need a crossover when the alignments are identical and a
straight through when they're mirrored?

Could it have been as simple as someone just imagining that all cables
would be straight-throughs because no one would deviate from the standard
pattern of router-[switch/hub]-Host?

I still remember my CCNA tutor having to stop and think when I pointed out
that if all sockets had the same pinout and all cables were crossovers
then there'd never be any problem..

On further thought, I can see that even under my supposed 'common sense'
approach, you'd still sometimes want straight-throughs for extension
purposes. Hmm, actually, no, you wouldn't would you, just make the inline
connectors also all crossover. So an extended link would be
[crossover-cable]-[crossover-inline]-[crossover-cable] and it would still
work perfectly.

So, what was the thinking? Does anyone have an idea?

Dave J.



No real answer, but I have no problem with the setup because I come from
the DCE/DTE era (Data Communications Equipment - eg modem - and Data
Terminal Equipment - eg teletype [yes, I know teletypes also used 80v
signalling for some versions]) where the interfaces were designed for
straight though cables as required by the ISO (also EIA and ECMA)
standards :-)

In networking, the switch (or hub) is DCE and the computer DTE, so logic
would suggest a continuation of the practise.

The more confusing issue IMHO is the cross-over cable crosses two pairs
and leaves two pairs straight through :-(

--
PeeGee

The reply address is a spam trap. All mail is reported as spam.
"Nothing should be able to load itself onto a computer without the
knowledge or consent of the computer user. Software should also be able
to be removed from a computer easily."
Peter Cullen, Microsoft Chief Privacy Strategist (Computing 18 Aug 05)
  #3  
Old March 16th 08, 10:17 PM posted to uk.comp.home-networking
Newshound
external usenet poster
 
Posts: 28
Default Idle question

No real answer, but I have no problem with the setup because I come from
the DCE/DTE era (Data Communications Equipment - eg modem - and Data


Ah the good old days.....never went anywhere without a null modem....


  #4  
Old March 18th 08, 11:57 AM posted to uk.comp.home-networking
Rob
external usenet poster
 
Posts: 19
Default Idle question


"Dave J." wrote in message
...
Can anyone offer an explanation for the ages-back decision to use two
different pin alignments for CAT-5/RJ45 networking plugs/sockets? You know
the way you need a crossover when the alignments are identical and a
straight through when they're mirrored?

Could it have been as simple as someone just imagining that all cables
would be straight-throughs because no one would deviate from the standard
pattern of router-[switch/hub]-Host?

I still remember my CCNA tutor having to stop and think when I pointed out
that if all sockets had the same pinout and all cables were crossovers
then there'd never be any problem..

On further thought, I can see that even under my supposed 'common sense'
approach, you'd still sometimes want straight-throughs for extension
purposes. Hmm, actually, no, you wouldn't would you, just make the inline
connectors also all crossover. So an extended link would be
[crossover-cable]-[crossover-inline]-[crossover-cable] and it would still
work perfectly.

So, what was the thinking? Does anyone have an idea?


I reckon you probably invented firewire without knowing (which, btw,
work great for networking under XP.)
--
Rob


  #5  
Old March 18th 08, 05:05 PM posted to uk.comp.home-networking
Alex Fraser
external usenet poster
 
Posts: 553
Default Idle question

"Rob" wrote in message
...
"Dave J." wrote in message
...
Can anyone offer an explanation for the ages-back decision to use two
different pin alignments for CAT-5/RJ45 networking plugs/sockets? You
know the way you need a crossover when the alignments are identical and
a straight through when they're mirrored?

[snip]
I reckon you probably invented firewire without knowing (which, btw,
work great for networking under XP.)


I take it Firewire is "all cables crossed" then. Not computer-related, but
SCART is like this too (for the audio in/out and CVBS in/out).

Back to Ethernet, links made between punch-down blocks would need to be
crossed too. That's fine if one end is in a wiring cupboard (or whatever)
and the other inside a wall-mounted socket in an office, but is that always
the case? (I have no idea, but if not and you forget which way you wired the
first end...)

Alex


  #6  
Old March 19th 08, 03:14 PM posted to uk.comp.home-networking
Rob
external usenet poster
 
Posts: 19
Default Idle question


"Alex Fraser" wrote in message
...
"Rob" wrote in message
...
"Dave J." wrote in message
...
Can anyone offer an explanation for the ages-back decision to use two
different pin alignments for CAT-5/RJ45 networking plugs/sockets? You
know the way you need a crossover when the alignments are identical and
a straight through when they're mirrored?

[snip]
I reckon you probably invented firewire without knowing (which, btw,
work great for networking under XP.)


I take it Firewire is "all cables crossed" then. Not computer-related, but
SCART is like this too (for the audio in/out and CVBS in/out).

Back to Ethernet, links made between punch-down blocks would need to be
crossed too. That's fine if one end is in a wiring cupboard (or whatever)
and the other inside a wall-mounted socket in an office, but is that
always the case? (I have no idea, but if not and you forget which way you
wired the first end...)


Yes, IEEE1394 cables are all cross-wired:
http://www.technick.net/public/code/...nbus_ieee_1394
(scroll down to Cables and connectors, if interested.)
--
Rob



  #7  
Old March 20th 08, 11:35 AM posted to uk.comp.home-networking
Dave J.
external usenet poster
 
Posts: 139
Default Idle question

In on Sun, 16 Mar 2008 12:58:11 +0000, in
uk.comp.home-networking, 'PeeGee' wrote:

Dave J. wrote:
Can anyone offer an explanation for the ages-back decision to use two
different pin alignments for CAT-5/RJ45 networking plugs/sockets? You know
the way you need a crossover when the alignments are identical and a
straight through when they're mirrored?

Could it have been as simple as someone just imagining that all cables
would be straight-throughs because no one would deviate from the standard
pattern of router-[switch/hub]-Host?

I still remember my CCNA tutor having to stop and think when I pointed out
that if all sockets had the same pinout and all cables were crossovers
then there'd never be any problem..

On further thought, I can see that even under my supposed 'common sense'
approach, you'd still sometimes want straight-throughs for extension
purposes. Hmm, actually, no, you wouldn't would you, just make the inline
connectors also all crossover. So an extended link would be
[crossover-cable]-[crossover-inline]-[crossover-cable] and it would still
work perfectly.

So, what was the thinking? Does anyone have an idea?

Dave J.



No real answer, but I have no problem with the setup because I come from
the DCE/DTE era (Data Communications Equipment - eg modem - and Data
Terminal Equipment - eg teletype [yes, I know teletypes also used 80v
signalling for some versions]) where the interfaces were designed for
straight though cables as required by the ISO (also EIA and ECMA)
standards :-)

In networking, the switch (or hub) is DCE and the computer DTE, so logic
would suggest a continuation of the practise.


That makes sense. Still doesn't quite make it correct, but it does make
sense.


The more confusing issue IMHO is the cross-over cable crosses two pairs
and leaves two pairs straight through :-(


Oh? Does the DCE/DTE standard have more than the data cables reversed?

Dave J.
  #8  
Old March 20th 08, 02:17 PM posted to uk.comp.home-networking
PeeGee
external usenet poster
 
Posts: 311
Default Idle question

Dave J. wrote:
In on Sun, 16 Mar 2008 12:58:11 +0000, in
uk.comp.home-networking, 'PeeGee' wrote:

Dave J. wrote:
Can anyone offer an explanation for the ages-back decision to use two
different pin alignments for CAT-5/RJ45 networking plugs/sockets? You know
the way you need a crossover when the alignments are identical and a
straight through when they're mirrored?

Could it have been as simple as someone just imagining that all cables
would be straight-throughs because no one would deviate from the standard
pattern of router-[switch/hub]-Host?

I still remember my CCNA tutor having to stop and think when I pointed out
that if all sockets had the same pinout and all cables were crossovers
then there'd never be any problem..

On further thought, I can see that even under my supposed 'common sense'
approach, you'd still sometimes want straight-throughs for extension
purposes. Hmm, actually, no, you wouldn't would you, just make the inline
connectors also all crossover. So an extended link would be
[crossover-cable]-[crossover-inline]-[crossover-cable] and it would still
work perfectly.

So, what was the thinking? Does anyone have an idea?

Dave J.


No real answer, but I have no problem with the setup because I come from
the DCE/DTE era (Data Communications Equipment - eg modem - and Data
Terminal Equipment - eg teletype [yes, I know teletypes also used 80v
signalling for some versions]) where the interfaces were designed for
straight though cables as required by the ISO (also EIA and ECMA)
standards :-)

In networking, the switch (or hub) is DCE and the computer DTE, so logic
would suggest a continuation of the practise.


That makes sense. Still doesn't quite make it correct, but it does make
sense.

The more confusing issue IMHO is the cross-over cable crosses two pairs
and leaves two pairs straight through :-(


Oh? Does the DCE/DTE standard have more than the data cables reversed?


DCE/DTE, as I used the terms above, are part of the ISO/EIA/ECMA
standards (the latter are virtually identical) and the standards defined
the pin-outs for the equipment. IIRC, apart from the physical
obstructions, the connectors were defined so that the two units would
plug in directly - the cable, therefore, was straight-through extension
lead.

The ethernet cross-over patch lead is confusing because the two data
pairs for 10 and 100Mbps are crossed over, the other pairs are not. If
you use such a cable with Gigbit ethernet, two data pairs are crossed,
two are not :-(

Thankfully, unless you are using old equipment (especially hubs) the
interface is auto-sensing and the patch lead is no longer a factor.
Cross-over leads are largely redundant unless you wish to connect two
computers directly, when auto-sensing is (or is that was?) not common
for NICs.

--
PeeGee

The reply address is a spam trap. All mail is reported as spam.
"Nothing should be able to load itself onto a computer without the
knowledge or consent of the computer user. Software should also be able
to be removed from a computer easily."
Peter Cullen, Microsoft Chief Privacy Strategist (Computing 18 Aug 05)
  #9  
Old March 21st 08, 12:35 PM posted to uk.comp.home-networking
Dave J.
external usenet poster
 
Posts: 139
Default Idle question

In on Tue, 18 Mar
2008 17:05:38 -0000, in uk.comp.home-networking, 'Alex Fraser' wrote:

Can anyone offer an explanation for the ages-back decision to use two
different pin alignments for CAT-5/RJ45 networking plugs/sockets? You
know the way you need a crossover when the alignments are identical and
a straight through when they're mirrored?

[snip]
I reckon you probably invented firewire without knowing (which, btw,
work great for networking under XP.)


I take it Firewire is "all cables crossed" then. Not computer-related, but
SCART is like this too (for the audio in/out and CVBS in/out).

Back to Ethernet, links made between punch-down blocks would need to be
crossed too. That's fine if one end is in a wiring cupboard (or whatever)
and the other inside a wall-mounted socket in an office, but is that always
the case? (I have no idea, but if not and you forget which way you wired the
first end...)


IIUYC, that had, umm.. crossed my mind..

My thought was that the standard could cope with that by defining
plug-plug as always crosover but (plug or device or socket) - (socket
or panel) as always straight through.

IOW as opposed to straight-through/crossover there would be 'connector
cable' or 'extension cable' - one defined as for connecting two standardly
wired sockets together and the other as extending a socket, the former
being always crossover and the latter being always straight-through. No
difficulty telling one from the other where it's cables and easy enough
for technicians to get used to as the wiring from devices to sockets or
patch panels would be identical.

I dunno, I meant it as 'idle question', just me reflecting my musings and
wondering if anyone else had thought similarly.

Dave J.


--
Freeware Open Source Internet Television / Video RSS player. Fetches Video
RSS feeds or retrieves from regular searches on Youtube or Google video.
Dozens of feeds as defaults. Science, Politics, Music, Geekery...
Miro - Downloadable from http://www.GetMiro.org - Worth a try!
  #10  
Old March 21st 08, 12:52 PM posted to uk.comp.home-networking
Dave J.
external usenet poster
 
Posts: 139
Default Idle question

In on Tue, 18 Mar 2008 11:57:24
-0000, in uk.comp.home-networking, 'Rob' wrote:

On further thought, I can see that even under my supposed 'common sense'
approach, you'd still sometimes want straight-throughs for extension
purposes. Hmm, actually, no, you wouldn't would you, just make the inline
connectors also all crossover. So an extended link would be
[crossover-cable]-[crossover-inline]-[crossover-cable] and it would still
work perfectly.

So, what was the thinking? Does anyone have an idea?


I reckon you probably invented firewire without knowing (which, btw,
work great for networking under XP.)


Firewire's something I know little about, for some reason (don't quite
know why) it's always come across to me as one of those gimmicky things
that's implemented on a few devices but is superseded within months or a
couple of years. Or, in some examples, before it's even released..

Dave J.
 




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Idle question Dave J. uk.comp.home-networking (UK home networking) 1 November 19th 06 06:16 PM
Idle Timeout/Keep alive Chris Watts uk.telecom.broadband (UK broadband) 4 November 14th 05 04:50 PM
ADSL Idle Timeout - is there such a thing? [email protected] uk.telecom.broadband (UK broadband) 7 November 5th 05 12:04 PM
PlusNet Idle Time Disconnect Mark Carver uk.telecom.broadband (UK broadband) 4 September 20th 05 05:22 PM
Idle Time Out (New Feature on Plusnet) Barney uk.telecom.broadband (UK broadband) 18 September 11th 05 01:48 PM


All times are GMT +1. The time now is 11:55 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.Content Relevant URLs by vBSEO 2.4.0
Copyright 2004-2019 BroadbanterBanter.
The comments are property of their posters.