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Why are commercially available 3-foot CAT5e patch cables wired 568B instead of A?

MichaelD

MichaelD

Lifer
Take a look at this. I almost ordered them until I saw their wiring schema. 😱

I plan on wiring my house 568A...B is crossover.

Even though my switch has auto MDI/MDIX, why would I want to mess with this? Advice, please.
 
Originally posted by: dexter333
Uh, as long as the two ends are the same a -> a or b -> b, then it'll work. A crossover is a -> b.
Click to expand...

Hi Dexter333. So what you're saying is that if all my drops to the patch panel are wired as 568A, and all the patch cables going from the patch panel to the swtich are wired 568B that everything will work just fine? I guess that does make sense...as long as the wires arent' crossed on any of the cables, it should all work, right?
 
MichaelD, 568B is not crossover. 568B is the north American standard for how the colors map to pins & pairs. 568A is the European standard. It happens that in both cases, the necessary pins are paired to be usable with Ethernet, so you can use either standard and it's fine. And a 568B patch cable can be used with a 568A cable plant. Now, if the SAME CABLE has one way on one end and one way on the other, then the cable is in fact non-standard, and ends up working out to cross-over Ethernet. Don't do that.

Don't use 568A in north America. Use 568B.
 
Originally posted by: cmetz
MichaelD, 568B is not crossover. 568B is the north American standard for how the colors map to pins & pairs. 568A is the European standard. It happens that in both cases, the necessary pins are paired to be usable with Ethernet, so you can use either standard and it's fine. And a 568B patch cable can be used with a 568A cable plant. Now, if the SAME CABLE has one way on one end and one way on the other, then the cable is in fact non-standard, and ends up working out to cross-over Ethernet. Don't do that.

Don't use 568A in north America. Use 568B.
Click to expand...


Wow, I've never heard that B is the North American standard...I'm in TX...how come anyone that's ever showed me how to make a cable or wire a keystone has showed me 568A? 😕 These are people that do this for a living, BTW.

I'm really confused!
 
OK, 568B is:

Orange-white, Orange, Green-white, Blue, Blue-white, Green, Brown-white, Brown

is that correct? My poor achin' head! 😱

Thanks, AT!
 
cause B is better... at elast it's what i learned first and remember

OW
O
GW
Bl
BlW
G
BrW
Br

🙂

course, not that it really matters cause A vs B is just the order of the wires, the actual connection points of the wires are the same
 
B is the US data standard, but A is often used (in US) by telco's for voice-over-ip, as well as multi-line phones. either will work, but it is easier to tell if you have data or voice by looking at the ends. than by learning the hard way.(fried electronics) ethernet doesn't like +/-25V AC voltages too much....
 
Originally posted by: MichaelD
OK, 568B is: Orange-white, Orange, Green-white, Blue, Blue-white, Green, Brown-white, Brown is that correct? My poor achin' head! 😱 Thanks, AT!
Click to expand...

Correct. I make my cables 568B.
 
lobadobadingdong, all Ethernet equipment is required to have input voltage protection far in excess of +/- 25V, I believe it's 1,000V actually. You know those funny looking blocky things near the Ethernet connector on your NICs? That's what it does. So if plugging a telephone or PBX line into your Ethernet equipment fries the Ethernet equipment, you have equipment that isn't complying with the spec.

I can only wish for users who could (a) look at cables before plugging them in and (b) would notice the difference between 568A and 568B wiring.

568 A and B are telco standards, they happen to be used now for data, but they evolved from the phone system. I'm sure if you trace it back far enough you end up with a Western Electric standard.
 
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