T568A or T568B? Check out what Fluke has to say
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Posted by Dmitri(Cabling-Design.com on January 13, 2005, 2:54 am
Please log in for more thread options 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 ------------------------------------- ##-----------------------------------------------## Article posted with Cabling-Design.com Newsgroup Archive http://www.cabling-design.com/forums no-spam read and post WWW interface to your favorite newsgroup - comp.dcom.cabling - 1068 messages and counting! ##-----------------------------------------------## | |||||||||||||||||||||||||||||||
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Posted by Robert Redelmeier on January 13, 2005, 3:35 am
Please log in for more thread options >
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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Posted by Dmitri(Cabling-Design.com on January 13, 2005, 3:57 am
Please log in for more thread options Hi, Robert!
Robert Redelmeier wrote: > 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 :-( > 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. > 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 ------------------------------------- ##-----------------------------------------------## Article posted with Cabling-Design.com Newsgroup Archive http://www.cabling-design.com/forums no-spam read and post WWW interface to your favorite newsgroup - comp.dcom.cabling - 1070 messages and counting! ##-----------------------------------------------## | |||||||||||||||||||||||||||||||
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Posted by Justin Time on January 13, 2005, 8:36 am
Please log in for more thread options 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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Posted by Dmitri(Cabling-Design.com on January 13, 2005, 5:00 pm
Please log in for more thread options Justin Time wrote:
> 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 ------------------------------------- ##-----------------------------------------------## Article posted with Cabling-Design.com Newsgroup Archive http://www.cabling-design.com/forums no-spam read and post WWW interface to your favorite newsgroup - comp.dcom.cabling - 1073 messages and counting! ##-----------------------------------------------## | |||||||||||||||||||||||||||||||
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> 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.