# T68a/t68b



## matt1124 (Aug 23, 2011)

Can you not make a crossover cable? A on one end, B on the other?


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## WronGun (Oct 18, 2013)

matt1124 said:


> Can you not make a crossover cable? A on one end, B on the other?




Possibly , I think I’m
Going to reterminate their line









Just going to remove their little block
And install a straight jack


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## WronGun (Oct 18, 2013)

Why do they even use these little term blocks , idk?


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## HackWork (Oct 2, 2009)

That is a mess.

You should see if you could pull a little slack on that blue cable coming in thru the flex loom and terminate an rj45 plug right on it.


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## WronGun (Oct 18, 2013)

That’s exactly what I just did and changed it to T68A, straight RJ45

I’ve always done T68A , not sure why theirs are B, we have 23 drops installed in this home all A


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## HackWork (Oct 2, 2009)

I thought B was the standard.

It doesn't make any difference what is used in the rest of the house, it only matters on that one cable.

As long as you use the same standard on both ends of each cable, it's fine. You can use B for the cable feeding the router and A on all the rest going out to the house.


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## matt1124 (Aug 23, 2011)

Don't get the IT guys started on A vs B.... I use B because an IT guy got all pissy I used A, he spent way too long trying to figure it what I did, I was still young and thought his opinion mattered so I stuck with B after that.


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## matt1124 (Aug 23, 2011)

WronGun said:


> Why do they even use these little term blocks , idk?
> 
> 
> Sent from my iPhone using Tapatalk


The cable company here sent me some guy that literally didn't tie his boots and tripped on the laces the whole time he was here. He called the main tech support number, and when he couldn't even describe what was happening to them beyond blinky lights, he had his boss come out to fix the problem.


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## cabletie (Feb 12, 2011)

Unless someone tells me otherwise it's always B. I don't know if I've ever wired for A.


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## active1 (Dec 29, 2009)

B spec for me unless told otherwise.
IMO A spec comes from copper telephone days.

The RJ45 4 pin phone plugs had the blue line 1 pair in the center.
That pair was not used on the T10 or T100.
If I was to guess the original intention 40 years ago was to have a pair for a POT line in the network cable. But it just never worked.
The other 7&8 pair were called shorting pairs for shorting with a resistor to program.
Pin Color Function 
1 White with Green +TD 
2 Green -TD 
3 White with Orange +RD 
4 Blue Not Used 
5 White with Blue Not Used 
6 Orange -RD 
7 White with Brown Not Used 
8 Brown Not Used

As far as I can tell B came from a crossover cable that was once needed to connect 1 PC to another. It wouldn't work without crossing the send and receive wires which doing so was called a crossover.
Perhaps it came from the fact the main server was wired A and the jacks B instead of using a crossover cable. Just guessing.


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## splatz (May 23, 2015)

Wrongun, it's immaterial that they used 568B. Think about it.


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## HackWork (Oct 2, 2009)

splatz said:


> Wrongun, it's immaterial that they used 568B. Think about it.


It definitely matters since he used A on the other side of that Cat5.


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## splatz (May 23, 2015)

HackWork said:


> It definitely matters since he used A on the other side of that Cat5.


Almost all network cables are auto mdi / mdix so it doesn't matter any more. 

But I think that's voice, not ethernet.


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## triden (Jun 13, 2012)

Canada is mostly "a" eh

Mixing A and B networks won't cause an issue. I wouldn't go out of your way to change it. All that matters is that the cable is the same on both ends.


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## splatz (May 23, 2015)

The TIA / EIA 568 standard, which is currently in rev D, contains both the 568A pinout and the 568B pinouts as acceptable for 4-pair UTP wiring. (STP too but everyone hates shielded.) Back in the 90s, the 568A standard was recommended as "preferred" but they were both in there. If someone specified one or the other that's their prerogative but it's not required by the standard. 

Even before the standard was becoming accepted and used in commercial wiring specs, people were already using 568B and it was a lot easier to get patch cords and patch panels and jacks made for 568B, so people generally ignored the recommendation. 

Note that the pairs are arranged the same way with either, it's just the colors are different. The pairs are arranged differently on the older USOC pinout used for analog phone lines. Now of course the electronics can't "SEE" the colors, only the pair arrangement, so the choice of 568B or 568A only matters to people looking at the pairs. The difference between a A patch panel and a B patch panel is the sticker with the color key on it. 

When you're making cross connects to analog phone lines, the 568A pinout matches the first two pairs (blue and orange) of the USOC pinout. So if you're using the cabling for two line phones, the colors match and cross connects are easier. Of course this is a pretty unusual application these days so don't worry about it. 

The 568B pinout was mainly for compatibility with some AT&T equipment, and T1s match the 568B pinout. But again its not something you'd need to deal with much these days on workstation cables. 

So for all practical purposes you'll want to just try to keep your life simple by matching all the pinouts in a facility, use all A or all B. But it's no big deal. 

Using voice grade jacks with screw terminals, which I still see some cheapskates putting in homes, is wrong on many levels and if you do it you should just quit the sport, if I was in charge I'd banish you to staple in insulation for the rest of your life.


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## HackWork (Oct 2, 2009)

splatz said:


> Almost all network cables are auto mdi / mdix so it doesn't matter any more.


So silly to knowingly do something wrong hoping it works. How much will a service call cost him to go and fix it if it doesn't work with that ONT and router?


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## splatz (May 23, 2015)

HackWork said:


> So silly to knowingly do something wrong hoping it works. How much will a service call cost him to go and fix it if it doesn't work with that ONT and router?


No no no, the wrong thing would be @WronGun messing with Verizon's work because he thinks he needs to to make it compatible with his cabling. His work is to install cabling, he did his thing, leave the rest between Verizon and the customer and / or IT guy. 

Just like you used to have to get polarity right on phone lines but hardly ever any more, it doesn't matter much, but still leave it to them. 

(BTW, I am still not sure what we're looking at, I've only see that terminal used as part of a NID for verizon's newer voice service around here, the ethernet handoff for your internet service is the port on the equipment.)


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## HackWork (Oct 2, 2009)

splatz said:


> No no no, the wrong thing would be @WronGun messing with Verizon's work because he thinks he needs to to make it compatible with his cabling. His work is to install cabling, he did his thing, leave the rest between Verizon and the customer and / or IT guy.


 No, it's best that he did exactly what he did to correct the problem.


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## splatz (May 23, 2015)

HackWork said:


> No, it's best that he did exactly what he did to correct the problem.


How do you know? Do you know what's at either end of that cable? There's really not enough to go on from the picture he posted. 

Is it his job? Is it what he was contracted to do? Remember a few weeks ago he wasted time trying to stack two wireless routers in the same house? 

You'd be the first one to point out that he shouldn't be worried about other people's work, except when it gives you something to argue about.


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## HackWork (Oct 2, 2009)

splatz said:


> How do you know? Do you know what's at either end of that cable?


 Yes, I do. The other end of the cable is terminated with the A standard as the OP said. 

The FIOS tech doesn't know his ass from his elbow, that's why they use that little adapter thing, because they aren't qualified enough to use normal network material/tools. 

WronGun notice an issue and corrected it. But by all means, tell him what he did was wrong...



> Is it his job?


 Yes, it is his job when they call him to fix the problem since he installed all the wiring.



> You'd be the first one to point out that he shouldn't be worried about other people's work, except when it gives you something to argue about.


 No, that's not true. It's his work that is the problem since he made the other end of the cable to A standard. It is you who is here arguing. Everything was fine until you came along and disagreed with what WronGun did (cut the adapter plate and terminate the cable to A). I strongly disagree with both your assertions that he shouldn't have to worry about it and he should just "hope" it will work with the wrong standard on one end.


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## splatz (May 23, 2015)

HackWork said:


> Yes, it is his job when they call him to fix the problem since he installed all the wiring.


So it's your problem if the customer says it's your problem, even if it isn't in your contract, or part of your work? Would it be wrongun's problem if the water pressure was too low? How about if the paint is the wrong color? 

Again, in the same situation ten other ways, you'd be telling wrongun he's crazy to get involved with something that isn't what he was contracted to do.


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## splatz (May 23, 2015)

HackWork said:


> Yes, I do. The other end of the cable is terminated with the A standard as the OP said.


I didn't say how the other end was terminated, I said what gear it's connected to at the other end. It's not impossible that the Verizon technician deliberatly terminated it 568B at one end and 568A at the other - that's how you make a crossover cable. (Also not ruling out it's for voice...) 

But it's far more likely it just doesn't matter since the gear is not polarity sensitive as I said in the first place.


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## HackWork (Oct 2, 2009)

splatz said:


> So it's your problem if the customer says it's your problem, even if it isn't in your contract, or part of your work?


 It is part of his work. He installed the wiring and didn't use the normal standard. If the customer had to get FIOS in they would most likely charge, and if the tech found the issue he would have said how the electricina who wired it did not use the normal standard and made WronGun look bad.

WronGun did exactly what he was supposed to in checking the FIOS guy's method to connect his own wiring.



> Would it be wrongun's problem if the water pressure was too low? How about if the paint is the wrong color?


 If you are going to argue, at least use relative examples and not pure hyperbole.



> Again, in the same situation ten other ways, you'd be telling wrongun he's crazy to get involved with something that isn't what he was contracted to do.


 Not true, as I explained a few times already. This is directly involved with his work. 

And to prove you wrong, go look at post #5 at the very beginning of the thread in which I told him to cut off the adapter and install an RJ45 plug with the A standard he used inside. This proves your statement about me absolutely false, but I won't expect you to admit that since you are just here to argue with me.


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## HackWork (Oct 2, 2009)

splatz said:


> I didn't say how the other end was terminated, I said what gear it's connected to at the other end. It's not impossible that the Verizon technician deliberatly terminated it 568B at one end and 568A at the other - that's how you make a crossover cable. (Also not ruling out it's for voice...)


 Don't blame me because you don't understand the OP and know nothing about FIOS.



> But it's far more likely it just doesn't matter since the gear is not polarity sensitive as I said in the first place.


Garbage idea. How about he does it right so that he doesn't have to go back and fix it?

Telling someone to knowingly leave the wrong standard in hopes that it might work is bad advice.


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## splatz (May 23, 2015)

HackWork said:


> It is part of his work. He installed the wiring and didn't use the normal standard. If the customer had to get FIOS in they would most likely charge, and if the tech found the issue he would have said how the electricina who wired it did not use the normal standard and made WronGun look bad.
> 
> WronGun did exactly what he was supposed to in checking the FIOS guy's method to connect his own wiring.


Your head is so far up your ass if you fart you'll blow your brains out. 

The "problem" wasn't with Wrongun's wiring, it was with Verizon's. 

Wrongun didn't so anything nonstandard or in any way affected by Verizon's work. 

If someone said different, it would be easy to defend by simply demonstrating the facts. Unless that someone has their head up their ass.


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## splatz (May 23, 2015)

HackWork said:


> This proves your statement about me absolutely false, but I won't expect you to admit that since you are just here to argue with me.


It's amazing how all these argumentative people are just coincidentally drawn to you, isn't it? :laughing:


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## HackWork (Oct 2, 2009)

splatz said:


> The "problem" wasn't with Wrongun's wiring, it was with Verizon's.


 That depends who you ask. The FIOS guy isn't going to say that to the customer as he hands them the invoice.


I'd like to point out the fact that you said twice how I would say it wasn't his work and I just want to argue here, even though at the very beginning of the thread I recommended he cut off the adapter and re terminate it, proving that you are the one arguing. Funny how you ignored that...


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## HackWork (Oct 2, 2009)

WronGun, I am sorry. I was wrong.

Go cut off the rj45 you installed and put back the adapter with the wrong standard. Splatz is right, you should just leave things like this and hope they work.


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## splatz (May 23, 2015)

HackWork said:


> WronGun, I am sorry. I was wrong.
> 
> Go cut off the rj45 you installed and put back the adapter with the wrong standard. Splatz is right, you should just leave things like this and hope they work.


Shut up, don't tell wrongun what to do. Once he understood that it didn't matter that his wiring was 586A, he'd have no longer given a flying **** what verizon does. 

Your penance is to spend this Sunday morning calling your customers and going back and undoing any mess you made in Verizon's fine work. Also write Verizon a letter apologizing for screwing with things you don't really understand. 

No wait fax it to them.


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## trentonmakes (Mar 21, 2017)

Who uses A?

We always go orange, green, blue, brown

Texting and Driving


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## WronGun (Oct 18, 2013)

It’s funny because B is what I’ve always used until the last house (before this current project) I did which is mentioned in this post...

On this older project Verizon brought their line in and used T68A, I had also bought a Leviton Cabinet with expansion boards and the manufactures directions ONLY showed wiring for T68A. This is why I made the switch to A on this second home. 

Also the wiring did matter on this project... the Verizon main came into the house and into a Cat 6 jack from this jack we have a patch cord jumping out to another jack on the same plate which is going to a large network switch area and a list of other media equipment and the modem. This project was technical 4 Asian Software engineers living here and partially working from home. 

If I kept the wiring the way it was the jumper wouldn’t of worked , I would’ve had to change the jacks to B in those 2 locations which isn’t a big deal. 

Maybe this is confusing but Verizon could only come in at a certain area and the clients wanted their switching equipment in another area. 


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## cabletie (Feb 12, 2011)

trentonmakes said:


> Who uses A?
> 
> We always go orange, green, blue, brown
> 
> Texting and Driving


Colors mean nothing without the pin assignment. 

I always remember the pairs as blue, orange, green, brown and slate. Repeat as necessary.


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## cabletie (Feb 12, 2011)

I cheaped out when I did my house. I have three locations in each room that has four ports. That is two coax a phone and a data. I never wanted to snake in another later. Because it was going to be so many cables, I decided to share the phone and data on one cat 5 . Computers only use two pairs to transmit and receive. So I punched down the blue, orange, and green on the RJ45 jack and the brown on the USOC jack. 

Down in the basement I pulled all the brown pairs out and punched them down on one patch panel and the first three pairs on another patch panel. I probably shouldn't been so cheap. Hopefully in the future with advancing speeds computers won't use all four pairs.


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## active1 (Dec 29, 2009)

cabletie said:


> I cheaped out when I did my house. I have three locations in each room that has four ports. That is two coax a phone and a data. I never wanted to snake in another later. Because it was going to be so many cables, I decided to share the phone and data on one cat 5 . Computers only use two pairs to transmit and receive. So I punched down the blue, orange, and green on the RJ45 jack and the brown on the USOC jack.
> 
> Down in the basement I pulled all the brown pairs out and punched them down on one patch panel and the first three pairs on another patch panel. I probably shouldn't been so cheap. Hopefully in the future with advancing speeds computers won't use all four pairs.


They say the gigabyte equipment requires all 4 pairs.
With the exception if it's backwards compatible and can be downgraded.


It's T568 Wrong Gun. Your forgetting the 5.

I was told to do A spec last year on a AFB job that didn't have any existing in the building. But the EC really didn't have their act together so I don't know where it came from. Could be the base chose A many years ago.


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## cabletie (Feb 12, 2011)

active1 said:


> They say the gigabyte equipment requires all 4 pairs.
> With the exception if it's backwards compatible and can be downgraded.


I wish I could stop myself from doing something stupid, especially when I know better. It was probably just as hard to separate them and punch them down as it was to pull another cat 5 or even 3 since it was just for voice. Oh well I could change it if I had to. 

It's been this way for at least ten years now. I'm happy with the speed, and we've had FIOS for at least five years. Maybe I still have an old router? 

After searching your statement, it seems 10 base T and 100 base T only use two pairs. The new 1000 base T users all four pairs.


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## splatz (May 23, 2015)

It's true gigabit uses all four pairs, there was a two pair gigabit but it never caught on. I would not sweat missing gigabit though. The odds that you'll use the over 100mb on any one jack at one time is pretty slim with normal internet usage. Even if your fios service delivers over 100mb, that's shared between everyone on the service, and not many sites you'd go to on the internet will feed at 100mb - it's way more than you'd need for even something very bandwidth intensive like streaming video in 4k (usually more like 25 mb). 

If you have a jack that you connect something that takes more bandwidth, like a wireless access point or etc., you might want to fix that, put all four pairs on the data and remove the phone jack. 

There is a slight worry that the ringing voltage on the brown pair would disrupt the data stream on the orange and green but really how often does your land line ring?


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## paulengr (Oct 8, 2017)

trentonmakes said:


> Who uses A?
> 
> We always go orange, green, blue, brown
> 
> Texting and Driving




A was for PBX (actual phones). B was for data. So the phone company always uses A.

But the big thing is that in half duplex Ethernet on a hub (not a switch) at 10 MBps everyone has to be on the same pair and at full duplex the transmit and receive pairs must be swapped at each end. When it was all 10 some people used B which was the standard and some used A. When 100/full duplex came out a lot of rewiring had to be done including getting rid of a lot of CAT3. Switch ports are A and end devices are B. As long as patch cords and ports are all the same at both ends though it doesn’t matter. The exception is switch to switch where since both ports are A you need a crossover cable (A at one end, B on the other). Many switches had a designated uplink port that was backwards (A) for convenience.

But these days most ports are auto MDI/MDI-X so the device automatically swaps if the wiring is messed up and nobody thinks about those details until it matters.

But as professionals to do it right wire all building ports to B unless the building is backwards.

I keep my crossover cables with a wild (pink) color so they don’t get mixed. A lot of industrial equipment is ancient and this stuff still matters.

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