# Cat 5e



## Chris1971 (Dec 27, 2010)

On the female connector end do you use the A or B termination? I'm thinking the A termination. Why is their an A or B option?


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## mikeh32 (Feb 16, 2009)

a is residential, b is commercial...

but you need to check the rest of the building.

I am doing a school where half is in a, half is in b, and some is just made up.


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## Chris1971 (Dec 27, 2010)

mikeh32 said:


> a is residential, b is commercial...
> 
> but you need to check the rest of the building.
> 
> I am doing a school where half is in a, half is in b, and some is just made up.


Thanks. It's a home. Why the difference?


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## FlyingSparks (Dec 10, 2012)

Chris1971 said:


> Thanks. It's a home. Why the difference?


I would do B in residential aswell. It really does not matter, just use the same scheme everywhere in that structure.


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## Dawizman (Mar 10, 2012)

Most of the world uses T568A, however America likes to do things their own way, which is where T568B came from , and is most widely used (originally standardized by AT&T) . The TIA/EIA-568 standard actually specifies that you use T568A for most terminations, except in certain cases (namely where you need a crossover). Many people continue to use the T568B for whatever reason (like I said, it is commonly used in the US because that's the way most people have done it).


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## wendon (Sep 27, 2010)

The punch down jacks are B aren't they? At least the ones I've used.


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## farlsincharge (Dec 31, 2010)

The ones I use have both configurations on them. Check the building and try and stick to the majority.


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## kbsparky (Sep 20, 2007)

Unless you have a specific piece of equipment that requires the "A" configuration, I'd stick with the "B" ----

Some of the GrayFox stuff requires "A" terminations, the only things I've ever encountered that does ...


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## 8V71 (Dec 23, 2011)

kbsparky said:


> Unless you have a specific piece of equipment that requires the "A" configuration, I'd stick with the "B" ----
> 
> Some of the GrayFox stuff requires "A" terminations, the only things I've ever encountered that does ...


The only difference between A and B is pair color kb. The wires still go to the right places so it doesn't make any difference.


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## xlink (Mar 12, 2012)

For existing buildings, match the rest of the installation so you don't have to check each connection if you need to move something. 

For new installations, check with the IT people because it's like a ground-up or ground-down issue. Everyone cares a lot about something that doesn't matter.

If it's up to you, pick one and do it that way for the rest of your life so you are less likely to screw up.


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## FlyingSparks (Dec 10, 2012)

xlink said:


> For existing buildings, match the rest of the installation so you don't have to check each connection if you need to move something.
> 
> For new installations, check with the IT people because it's like a ground-up or ground-down issue. Everyone cares a lot about something that doesn't matter.
> 
> If it's up to you, pick one and do it that way for the rest of your life so you are less likely to screw up.


Ground up in an IT environment.


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## erics37 (May 7, 2009)

I've never seen anything done in a configuration other than B around here, resi or commercial or anything.


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## FlyingSparks (Dec 10, 2012)

They had a contractor come in to run cat 6 for a portion of a somewhat older building on our campus. They misinterpreted (didn't read) the engineer's plan. They terminated it using A, my organization made them redo it. About 2400 terminations.


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## Jlarson (Jun 28, 2009)

No specs you get what my data guy feels like rolling with the day, A or B, he's weird :laughing:. Don't like it, tough cookies.


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## xlink (Mar 12, 2012)

From https://en.wikipedia.org/wiki/TIA/EIA-568 :

TIA/EIA-568-B specifies that horizontal cables should be terminated using the T568A pin/pair assignments, or "optionally, per [T568B] if necessary to accommodate certain 8-pin cabling systems". Despite this instruction, many organizations continue to implement T568B for various reasons, chiefly associated with tradition (T568B is equivalent to AT&T 258A).

From the same page:

TIA/EIA-568 was developed through the efforts of more than 60 contributing organizations including manufacturers, end-users, and consultants. Work on the standard began with the Electronic Industries Alliance (EIA), a standards organization, to define standards for telecommunications cabling systems. EIA agreed to develop a set of standards, and formed the TR-42 committee,[1] with nine subcommittees to perform the work. The work continues to be maintained by TR-42 within the Telecommunications Industry Association.


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## don_resqcapt19 (Jul 18, 2010)

xlink said:


> ..."optionally, per [T568B] if necessary to accommodate certain 8-pin cabling systems". ...


I don't understand. Electrically the A and B connections are identical. The only difference is you switch the location of the orange and green pairs. Why would you need to use one over the other to "accommodate certain 8-pin cabling systems"?
http://www.google.com/imgres?imgurl...ed=0CCwQ9QEwAA&dur=618] 568a and 568b pinouts


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## BBQ (Nov 16, 2010)

From Wikipedia.

https://en.wikipedia.org/wiki/TIA/EIA-568#T568A_and_T568B_termination



> TIA/EIA-568-B specifies that horizontal cables should be terminated using the T568A pin/pair assignments, or "optionally, per [T568B] if necessary to accommodate certain 8-pin cabling systems". *Despite this instruction, many organizations continue to implement T568B for various reasons, chiefly associated with tradition (T568B is equivalent to AT&T 258A).*


We use B, I guess by tradition.

Further down the wiki page I found this is interesting if true.

https://en.wikipedia.org/wiki/TIA/EIA-568#Theory



> The original idea in wiring modular connectors, as seen in the registered jacks, was that the first pair would go in the center positions, the next pair on the next outermost ones, and so on. Also, signal shielding would be optimized by alternating the "live" and "earthy" pins of each pair. *The TIA/EIA-568-B terminations diverge slightly from this concept because on the 8 position connector, the resulting pinout would separate the outermost pair too far to meet the electrical echo requirements of high-speed LAN protocols.*


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## FastFokker (Sep 18, 2012)

I only do 568A... But I only do resi.


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## 8V71 (Dec 23, 2011)

> TIA/EIA-568-B specifies that horizontal cables should be terminated using the T568A pin/pair assignments...


What termination do you use if the run is vertical. :blink:



> TIA/EIA-568 was developed through the efforts of more than 60 contributing organizations including manufacturers, end-users, and consultants.


What they really did was round up 60 people off the street, blindfolded them, and told them to shove this cable into the connector. Then they studied the results and went with the connection scheme most duplicated. :laughing:


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## mikeh32 (Feb 16, 2009)

There is a whole science behind the wiring of cat6, and how the pins are arranged.


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## chewy (May 9, 2010)

mikeh32 said:


> There is a whole science behind the wiring of cat6, and how the pins are arranged.


An inspector was telling me that when I did my terminations I was going to fail because I had done a side entry into the jack and that the conductors were now all different lengths, I started doing side entrys with 6a due to the fact there wasn't enough depth in the box to get the minimum bend radius. To me he was just being a nitpicking idiot and all my work is certified with DTXs. Do you think there is any issue with pairs in the same cable being at a max of 10mm longer than the others, I'm thinking at max Blue and brown might be 5mm longer than orange and green in each jack.


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## Dawizman (Mar 10, 2012)

If your dtx says it's good, then it's good. We've only done a few 6a jobs, but they have all either been boxless (emt from the tray, down the wall, and a nail on low voltage ring, or they have been deep 4 squares, with extensions and mud rings, giving plenty of room for rear entry, and slack.


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## chewy (May 9, 2010)

Dawizman said:


> If your dtx says it's good, then it's good. We've only done a few 6a jobs, but they have all either been boxless (emt from the tray, down the wall, and a nail on low voltage ring, or they have been deep 4 squares, with extensions and mud rings, giving plenty of room for rear entry, and slack.


Its an inspector the client hires, its govt work type stuff so it supersedes our actual code.


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## Dawizman (Mar 10, 2012)

I know exactly what you mean. We do quite a bit of work for the Canadian armed forces, and they have a couple guys continually checking up on us to make sure we follow their spec exactly. Their spec is several hundred pages long, and each job has sub-specs that they want followed as well. If the "inspectors" hint that they don't like the way something is done, we will usually take the hint & change our method accordingly. Sometimes, however, we tell them that this is the best way to do it, go pound salt.

I don't mind too much. We will do the job the way they want it done. We bid accordingly, and make very good money on these jobs.


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## xlink (Mar 12, 2012)

Dawizman said:


> Their spec is several hundred pages long, and each job has sub-specs that they want followed as well.


I did a CBSA job that had spec's that contradicted each other. They just copy and paste to make the document longer without worrying about what it contains. I suspect the engineers are paid by the page.


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## MisterCMK (Jul 5, 2009)

xlink said:


> I did a CBSA job that had spec's that contradicted each other. They just copy and paste to make the document longer without worrying about what it contains. I suspect the engineers are paid by the page.


Sounds like most low-voltage specs anymore...


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## Jlarson (Jun 28, 2009)

BBQ said:


> Further down the wiki page I found this is interesting if true.


You know what that is called. A ****ing clue. When you design something that touchy it's time to revisit the drawing board.


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## 8V71 (Dec 23, 2011)

BBQ said:


> Further down the wiki page I found this is interesting if true.





> The original idea in wiring modular connectors, as seen in the registered jacks, was that the first pair would go in the center positions, the next pair on the next outermost ones, and so on. Also, signal shielding would be optimized by alternating the "live" and "earthy" pins of each pair. *The TIA/EIA-568-B terminations diverge slightly from this concept because on the 8 position connector, the resulting pinout would separate the outermost pair too far to meet the electrical echo requirements of high-speed LAN protocols.*


I 100% agree with the original idea part *which was never implemented. *
I posted the test results of this problem in a recent Shockdoc?? thread. However, I have a problem with the mention of live and earthy pins because as far as I know there is no such thing. These are balanced pairs with signals on both wires, the same signals only inverted. It would loosely be like running different phases of the same supply in seperate conduits if you seperated the pairs like the original idea would.

My knowledge only extends to the equipment that we design and I would really like for someone to post some hard facts about why A is better than B or vice versa because I don't know much about the actual cable itself.


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## don_resqcapt19 (Jul 18, 2010)

How does "B" separate the pairs any differently than "A"? Ethernet uses pins 1, 2, 3 & 6. The only difference in the wiring for the two systems is that "B" uses the orange pair for pins 1&2 and the green pair for pins 3&6, while "A" uses the green pair for pins 1&2 and the orange pair for pins 3&6.


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## Dawizman (Mar 10, 2012)

don_resqcapt19 said:


> How does "B" separate the pairs any differently than "A"? Ethernet uses pins 1, 2, 3 & 6. The only difference in the wiring for the two systems is that "B" uses the orange pair for pins 1&2 and the green pair for pins 3&6, while "A" uses the green pair for pins 1&2 and the orange pair for pins 3&6.


I'd have to agree. From a performance aspect, A & B should be the same.


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## 8V71 (Dec 23, 2011)

don_resqcapt19 said:


> How does "B" separate the pairs any differently than "A"? Ethernet uses pins 1, 2, 3 & 6. The only difference in the wiring for the two systems is that "B" uses the orange pair for pins 1&2 and the green pair for pins 3&6, while "A" uses the green pair for pins 1&2 and the orange pair for pins 3&6.


I agree, it shouldn't make a difference. I'm just looking for a reason for the 2 different standards and why they are so tightly enforced. Like FlyingSparks example where they made them redo 2400 connections. I do know the cable pairs have different twist rates for crosstalk reasons so I was wondering if that somehow factors into the preference. And then there is Gigabit, which uses all 4 pairs.


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## Dawizman (Mar 10, 2012)

8V71 said:


> I agree, it shouldn't make a difference. I'm just looking for a reason for the 2 different standards and why they are so tightly enforced. Like FlyingSparks example where they made them redo 2400 connections. I do know the cable pairs have different twist rates for crosstalk reasons so I was wondering if that somehow factors into the preference. And then there is Gigabit, which uses all 4 pairs.


But if you think about it, one end will always transmit on pins 1&2, and the other will always transmit on 3&6. So it doesn't matter whether you use the a standard, or the b standard.

The reason that both wiring schemes exist is because when the EIA created the 568 specification back in the early 90's there were already a lot of cable plants terminated to the WECO / ATT-258-A standard, so they decided to allow both wiring methods in the spec. They do however specify that new installations should use the 568A scheme. Some places strictly enforce one of the two schemes likely to keep everything uniform throughout their entire organization. 568B seems to be most widely used in the US, as it was originally developed and used by AT&T.


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## 8V71 (Dec 23, 2011)

Dawizman said:


> Some places strictly enforce one of the two schemes likely to keep everything uniform throughout their entire organization.


OK, so it's more of a color anal retentive thing? :laughing: I looked at my test cables a few weeks back when this subject came up and found them to be about 50/50. These are just short off the shelf already terminated cables.


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## Dawizman (Mar 10, 2012)

8V71 said:


> OK, so it's more of a color anal retentive thing? :laughing: I looked at my test cables a few weeks back when this subject came up and found them to be about 50/50. These are just short off the shelf already terminated cables.


For the most part, yes. Green & Orange are both twisted very similar to each other, and with 10/100 Ethernet, they are both used by one end for transmitting. 1000baseT does make use of the other two pairs, but they use the same colors on both wiring schemes. In reality, 568A might have a performance advantage over 568B in one direction, but 568B would have the same advantage going the opposite direction. In the end, it's a toss-up.

There are many other factors that affect performance, and are often overlooked by those who are not familiar with the 568 specification. How your cables are run plays a huge part in performance. Bending cables too tight, pulling them too tight & cable tying them tightly, running your cables too close to electrical for long stretches, and using low quality products are all detrimental to performance. Will the cable still work? Yes, most likely, but if you try to certify poorly installed cables, especially to cat6+ specs, it will likely fail. The link might auto negotiate to 1000mbps (or 100 if that's all the equipment is capable of), but you will likely see a high error rate on longer runs.


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## Hackster (Jun 15, 2013)

8V71 said:


> I agree, it shouldn't make a difference. I'm just looking for a reason for the 2 different standards and why they are so tightly enforced.


I thought the only reason for 2 different standards was so that you can make a cross-over cable by using A on one end and B on the other?


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## 8V71 (Dec 23, 2011)

Hackster said:


> I thought the only reason for 2 different standards was so that you can make a cross-over cable by using A on one end and B on the other?


That wouldn't work. Still need to swap another pair.


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## Hackster (Jun 15, 2013)

8V71 said:


> That wouldn't work. Still need to swap another pair.


Is this something new?


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## Dawizman (Mar 10, 2012)

8V71 said:


> That wouldn't work. Still need to swap another pair.


No, that is how you make a crossover cable. Crossover cables are only used in 10/100 networks, so only Orange & green pairs need to be switched. Crossover cables are not required on gigabit connectors because Auto-MDIX is part of the 1000baseT spec. Auto-MDIX is a protocol in which the device randomly selects whether it transmits on pins 1&2 or 3&6.


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## 8V71 (Dec 23, 2011)

Lemme look at my crossovers and double check. I made them about 10 years ago.


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## 8V71 (Dec 23, 2011)

Nevermind then.....I was wrong, thanks Dawizman.


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## jeffmoss26 (Dec 8, 2011)

I always use B. That's how I was taught and I almost never run into A, except in some weird residential panels.


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## FlyingSparks (Dec 10, 2012)

8V71 said:


> I agree, it shouldn't make a difference. I'm just looking for a reason for the 2 different standards and why they are so tightly enforced. Like FlyingSparks example where they made them redo 2400 connections. I do know the cable pairs have different twist rates for crosstalk reasons so I was wondering if that somehow factors into the preference. And then there is Gigabit, which uses all 4 pairs.


That was because my boss is an anal person. Did it really matter? No. Did we pay them to do 'a'? No. Did we guarantee extra work for 5 techs? Yes. They were a large firm -- so no sleep lost on our end. Lol


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