T568A or T568B? Check out what Fluke has to say
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T568A or T568B? Check out what Fluke has to say

 
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Dmitri(Cabling-Design.com
Guest
Posted: Thu Jan 13, 2005 4:54 am    Post subject: T568A or T568B? Check out what Fluke has to say Reply with quote
I'm fully aware that it looks like I'm beating up a dead horse, but
there's been a (relatively) new piece of evidence published by Fluke on
the 15+ years old discussion. I think it's worth to look at if you are
making this decision for yourself or the customer.

In a nutshell: you've got to play along with the manufacturer(s) of your
choice: if they optimized their cables and connectivity for T568B, you
will have a hard time making it pass RL if you installed it on T568A, and
Fluke gives you some testing data to substantiate that claim.

In my mind, the tricky part is: how do you get them to tell you which
pinout they were optimizing for? Alternatively, you could stay within
one-manufacturer solution and hope that they worked that out for you and
have gotten the cable factory to talk to the connectivity factory before
they released the product.

Careful with the link, it's long and ugly, but once you get there, the
page reads very easily, even has a nice little touch with that animation
of A changing into B. Kudos to A. Young @ Fluke who put this together.

http://kb.flukenetworks.com/display_results.asp?sid=3&p=%2Fdtx+series%2Fshould%5Fi%5Fcable%5Fto%5Ft568a%5For%5Ft568b%5Fis%5Fthere%5Fa%5Fdifference%2Ehtm

If the link did not work for you, go to www.flukenetworks.com and search
for document ID "EVE- 21 1004-AY0 90 0"

--
Dmitri Abaimov, RCDD
http://www.cabling-design.com
Cabling Forum, color codes, pinouts and other useful resources for
premises cabling users and pros
http://www.cabling-design.com/homecabling
Residential Cabling Guide
-------------------------------------




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Robert Redelmeier
Guest
Posted: Thu Jan 13, 2005 5:35 am    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Dmitri(Cabling-Design.com) <info_at_cabling-design_dot_com@foo.com> wrote:
Quote:
In my mind, the tricky part is: how do you get them to tell
you which pinout they were optimizing for? Alternatively,
you could stay within one-manufacturer solution and hope
that they worked that out for you and have gotten the cable
factory to talk to the connectivity factory before they
released the product.

http://kb.flukenetworks.com/display_results.asp?sid=3&p=%2Fdtx+series%2Fshould%5Fi%5Fcable%5Fto%5Ft568a%5For%5Ft568b%5Fis%5Fthere%5Fa%5Fdifference%2Ehtm


Thanks for the link. I would have been a bit more convinced
if the customer repeated that termination -A & -B to convince
me it wasn't a soft/skewed punchdown. And tried a different
run of cable that hadn't been kinked :)

I notice they didn't report Cat3, Cat5, Cat5e or length.
I'm surprised that the mfr would admit which are the worst
pairs or would even know without a lot number. If compromises
have to be made on a cable, I'm very surprised they'd color
the worst pair orange. Blue or Brown should get the boot.

I'm not entirely surprised that 3,6 are worst on the jack
(USOC straddle might be good for the wires, but the PCB
traces will be longer).

In short, I'm not counting on it.

-- Robert
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Dmitri(Cabling-Design.com
Guest
Posted: Thu Jan 13, 2005 5:57 am    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Hi, Robert!

Robert Redelmeier wrote:

Quote:
Thanks for the link. I would have been a bit more convinced
if the customer repeated that termination -A & -B to convince
me it wasn't a soft/skewed punchdown. And tried a different
run of cable that hadn't been kinked :)

Well, that and published amount of tests that were run and the ambient
temperature and ... OK, let us get real here: glorious days of big bucks
put into cabling R&D are over, at least for a while. We gotta learn how to
survive on that limited information that is possible to scavenge from free
sources, and basically use what's available. So, this will have to do :-(

Quote:
I notice they didn't report Cat3, Cat5, Cat5e or length.
I'm surprised that the mfr would admit which are the worst
pairs or would even know without a lot number. If compromises
have to be made on a cable, I'm very surprised they'd color
the worst pair orange. Blue or Brown should get the boot.

That was CAT6 link as the test tag states. Also, judging by the
attenuation I'd say it was exactly 100 meters of a decent (but not CAT6+)
CAT6 cable. No way to guess on origins of the jacks though. If I were to
guess, I'd say they used jack-to-jack setup without a patch panel simply
because it's easier to put together.

Quote:
I'm not entirely surprised that 3,6 are worst on the jack
(USOC straddle might be good for the wires, but the PCB
traces will be longer).

These days they make pins twist so much before they even hit the PCB that
I would not be so sure about which pair is better or worse.

Here I go with the link again: I don't think it came out right last time.

http://kb.flukenetworks.com/display_results.asp?sid=3&p=%2Fdtx+series%2Fshould%5Fi%5Fcable%5Fto%5Ft568a%5For%5Ft568b%5Fis%5Fthere%5Fa%5Fdifference%2Ehtm

Best regards!

--
Dmitri Abaimov, RCDD
http://www.cabling-design.com
Cabling Forum, color codes, pinouts and other useful resources for
premises cabling users and pros
http://www.cabling-design.com/homecabling
Residential Cabling Guide
-------------------------------------

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Justin Time
Guest
Posted: Thu Jan 13, 2005 6:36 pm    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
I'm curious, was this a one-time test? The article doesn't really give
an indication. That, along with so many other factors that can affect
a termination like the pressure applied to the wire, the angle of the
punchdown tool and so many other things can affect a termination. One
test result, no matter how dramatic, is statistically insignificant.
Rodgers Platt
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Dmitri(Cabling-Design.com
Guest
Posted: Thu Jan 13, 2005 7:00 pm    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Justin Time wrote:


Quote:
I'm curious, was this a one-time test? The article doesn't really give
an indication. That, along with so many other factors that can affect
a termination like the pressure applied to the wire, the angle of the
punchdown tool and so many other things can affect a termination. One
test result, no matter how dramatic, is statistically insignificant.
Rodgers Platt

All true, no questions asked. But then, again, has anyone else
conducted/published a statistically valid one? Gotta work with what's
available...

On a side note: I know it was not a R&D project on a government's grant
;-), but I do not expect Fluke guys to be absolutely silly and not
exercise at least some degree of decency conducting the test. I would
assume things like randomly picking the parts, carefully doing the
terminations and maybe even multiple (but not statistically significant, I
agree) tests have been done.


--
Dmitri Abaimov, RCDD
http://www.cabling-design.com
Cabling Forum, color codes, pinouts and other useful resources for
premises cabling users and pros
http://www.cabling-design.com/homecabling
Residential Cabling Guide
-------------------------------------


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Article posted with Cabling-Design.com Newsgroup Archive
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Robert Redelmeier
Guest
Posted: Thu Jan 13, 2005 7:21 pm    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Dmitri(Cabling-Design.com) <info_at_cabling-design_dot_com@foo.com> wrote:
Quote:
On a side note: I know it was not a R&D project on a government's
grant ;-), but I do not expect Fluke guys to be absolutely silly
and not exercise at least some degree of decency conducting the

Nope. This wasn't their test, but a one-off report from
a customer of theirs.

-- Robert
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Dmitri(Cabling-Design.com
Guest
Posted: Fri Jan 14, 2005 7:26 am    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Robert Redelmeier wrote:

Quote:
On a side note: I know it was not a R&D project on a
government's
grant ;-), but I do not expect Fluke guys to be absolutely silly
and not exercise at least some degree of decency conducting the

Nope. This wasn't their test, but a one-off report from
a customer of theirs.

-- Robert


Rats! You're right, it's right there: "collected by a customer". I guess,
you cannot expect any decency from a customer, conducting a test ... Just
kidding ;-)

It does not sound right that Fluke cannot perform a simplest test and has
to rely on a customer. Tough times...

--
Dmitri Abaimov, RCDD
http://www.cabling-design.com
Cabling Forum, color codes, pinouts and other useful resources for
premises cabling users and pros
http://www.cabling-design.com/homecabling
Residential Cabling Guide
-------------------------------------


##-----------------------------------------------##
Article posted with Cabling-Design.com Newsgroup Archive
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glen herrmannsfeldt
Guest
Posted: Fri Jan 14, 2005 8:01 am    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Dmitri(Cabling-Design.com) wrote:

Quote:
I'm fully aware that it looks like I'm beating up a dead horse, but
there's been a (relatively) new piece of evidence published by Fluke on
the 15+ years old discussion. I think it's worth to look at if you are
making this decision for yourself or the customer.

In a nutshell: you've got to play along with the manufacturer(s) of your
choice: if they optimized their cables and connectivity for T568B, you
will have a hard time making it pass RL if you installed it on T568A, and
Fluke gives you some testing data to substantiate that claim.

Does anyone ever test cables from both ends?

I don't think I am convinced, anyway. There are a number of
possible differences between cables, the exact mechanics of
crimping the connector on, the positioning of the pairs
inside the cable, that one should not be surprised about
small differences between cables.

For any cable less than about 80m there should be plenty of
margin to go around. For those making 100m cables,
keep trying until it is perfect.

-- glen
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Justin Time
Guest
Posted: Fri Jan 14, 2005 7:42 pm    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Does anyone ever test cables from both ends?

Actually, the testers do it now automatically. The "smart remotes" in
use since '95 or so have all tested from both directions. If you had
one of the original Pentascanners or one of the other early Cat 5
Testers you had to test each cable twice. Once from the patch panel,
the other from the workstation in order to be compliant with TSB-40A.
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James Knott
Guest
Posted: Sat Jan 15, 2005 3:29 am    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Dmitri(Cabling-Design.com wrote:

Quote:
I'm fully aware that it looks like I'm beating up a dead horse, but
there's been a (relatively) new piece of evidence published by Fluke on
the 15+ years old discussion. I think it's worth to look at if you are
making this decision for yourself or the customer.


Given that you're using the exact same pairs, I'd be suspicious of any test
that says one or the other method is bad. That sort of test should be
repeated with several different cable samples, to reduce chance of error.
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James Knott
Guest
Posted: Sat Jan 15, 2005 3:32 am    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Dmitri(Cabling-Design.com wrote:

Quote:
I'm curious, was this a one-time test?  The article doesn't really give
an indication.  That, along with so many other factors that can affect
a termination like the pressure applied to the wire, the angle of the
punchdown tool and so many other things can affect a termination.  One
test result, no matter how dramatic, is statistically insignificant.
Rodgers Platt

All true, no questions asked. But then, again, has anyone else
conducted/published a statistically valid one? Gotta work with what's
available...


I believe there's an ancient saying: "The plural of anecdote is not data".

If someone wants to make a such a claim, they should run multiple tests,
with many samples of wire, from different spools and manufacturers.
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Zeb
Guest
Posted: Wed Jan 19, 2005 8:02 am    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
Thanks for the infor, certainly it was a good reading

Zeb
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ayoung
Guest
Posted: Mon Apr 11, 2005 7:29 pm    Post subject: Re: T568A or T568B? Check out what Fluke has to say Reply with quote
From the author of the article in question:

If you doubt the conclusion, please try it yourself and let me have the
data. I decided only to publish one set of data in order not to overwhelm
the reader - a common complaint I receive. This conclusion is also known
by cable manufacturers as well - they may just decide not to tell you.

There are indeed variables in this experiment. However, when these are
taken into account, the conclusion is still the same. If the cable has
significantly less performance on the orange pair for RL and you connect
it to an outlet that has its worst pair for RL on 3,6; wiring it to T568-A
is not the first choice.

The shorter the length of the link, the less impact this will have of
course, since the contribution from the cable is reduced and the
contribution of the connectors become an issue.

In recent months I have started seeing connectors with equally good
performance on all pairs. I believe this is where we want to be. And no, I
am not telling you which ones - but they are not cheap.

Kind regards

Adrian Young
Fluke Networks



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