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General question(s) on Ethernet crimping / cables

xentr_thread_starter
Time to go back and do them all in B. :p

T568B is absolutely the modern standard. But the key is consistency. If you have an entire building wired in 'A', then you have to stick to that or recable the building. Going from A to B makes a crossover connection. So if you start patching in 'A', and that patching continues a run from a patch panel that's punched down in B, then you'll end up with a crossover connection. So all-in-all, stick to B.

I think the design for the standard is a carry forward from a ways back when interference could be an issue if the twisting wasn't completed right to the cable termination. (And crossover negotiation wasn't automatic.) You need to make sure that 'like pairs' always terminate together in order to maintain signal integrity. The green pair being split to either side of the blue is done to maintain backwards compatibility. But separating and organizing the colors is always the most annoying part of the cabling work IMO. Thousands of crimps in, and I still ask myself that same question frequently.

Yes but would that matter at all for a cable that's done in A end to end? It's still pin to pin the same output as one done in B?
 
Shortish electromagnetic field explanation...

Wiring actually has left hand rule/right hand rule depending on if your talking about hole/eletron flow vs proton flow. But basically take a wire (ethernet having 8 of them) and each pair is a send and receive. Now grab a ethernet cable and pretend all the solid colors are sends going 1 direction and all the recieves are going back. Grabbing the cable in your left hand and sticking out your thumb pretending to follow a solid orange wire the electromagnetic field it generates sending power down the line rotates in the direction of your fingers. Now flip your hand over and grab it again and pretend it is a orange striped wire instead. Your fingers wrap around a different direction. These two magnetic fields kinda cancel eachother out.

Now if that twisted pair of orange wires were both sending data the same way the magentic fields would amplify or it could introduce interference from 1 line to another.

---

An A-A cable or a B-B cable will perform the same.
 
Yes but would that matter at all for a cable that's done in A end to end? It's still pin to pin the same output as one done in B?
If its A from device-to-device, you're fine. It's only if you add a patch panel, wall jack, extension, etc where one piece of cable might become B instead.

But even so, I can't think modern devices would really care if you did accidentally have a crossover cable.

In my "laziness" I usually only do patch panel to wall jack, so it's always punch downs instead. I'm not a fan of crimping RJ45 ends, though I've yet to try those passthru crimpers. I'd rather buy a cheap pre-made patch cable for the end hookup.
 
xentr_thread_starter
I caved to peer pressure and re-terminated the cables to "B". :)

On another note..... creating my own custom length patch cables is not anywhere near as satisfying as I thought it would be.
 
Small tip if your crimper didn't come with it print off the a/b spec orders and tape them to the handle, lid of the case the crimpers came in or whatever so it is always handy when using it.
 
xentr_thread_starter
Small tip if your crimper didn't come with it print off the a/b spec orders and tape them to the handle, lid of the case the crimpers came in or whatever so it is always handy when using it.

It's got both on it, I just need to get the orientation worked out in my mind so I know which way is pin one. :)
 
It's got both on it, I just need to get the orientation worked out in my mind so I know which way is pin one. :)
I make sure the oritentation is always with the locking tab away from me so I can see the wires in the connector, and the wire towards me. Basically pretending that I'm about to plug it into something with the locking tab down.
 
Yes but would that matter at all for a cable that's done in A end to end? It's still pin to pin the same output as one done in B?

This has already been answered, but it doesn't matter if its all the same end to end. But if you go back later, or sell the house and someone else comes in, it can be confusing if it's not to current standard.

Technically devices should negotiate, but what CAN happen with a mix is a lowered negatiation speed. So you could end up spending hours troubleshooting a network speed issue that ends up being a lowered negotiation speed because of a mix of cable standards within the same run. Not that I speak from experience or anything... :rolleyes:
 
Shortish electromagnetic field explanation...

Wiring actually has left hand rule/right hand rule depending on if your talking about hole/eletron flow vs proton flow. But basically take a wire (ethernet having 8 of them) and each pair is a send and receive. Now grab a ethernet cable and pretend all the solid colors are sends going 1 direction and all the recieves are going back. Grabbing the cable in your left hand and sticking out your thumb pretending to follow a solid orange wire the electromagnetic field it generates sending power down the line rotates in the direction of your fingers. Now flip your hand over and grab it again and pretend it is a orange striped wire instead. Your fingers wrap around a different direction. These two magnetic fields kinda cancel eachother out.

Now if that twisted pair of orange wires were both sending data the same way the magentic fields would amplify or it could introduce interference from 1 line to another.

---

An A-A cable or a B-B cable will perform the same.

Aaaand... I've learned something new. I always knew about interference, but I've never considered the actual physics breakdown.
 
Ran across one of his videos and he was wearing a hoodie with this picture on it. Didn't listen to a word he said found the shirt and figured I'd share it here after some of the a vs b comments.

 

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