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RJ45 CAT6 crimp - is this one reliable?

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wraper:

--- Quote from: Veteran68 on August 28, 2023, 12:20:54 pm ---You could make up your own color scheme and keep it the same on both ends and it would work, though you'd still want to be sure to separate the RX pair to minimize crosstalk interference. However it would for sure annoy the next network technician or electrician to come along and try to figure out what's going on from a visual inspection of the cable. The standards are easily recognizable by experienced installers.

--- End quote ---
You can swap colors but allocation of twisted pairs must remain exactly the same, otherwise it won't work.

bitwelder:

--- Quote from: Veteran68 on August 28, 2023, 12:20:54 pm ---
T568A was preferred (and initially standardized by ANSI) years ago for construction due to backwards compatibility with common POTS wiring for phones and faxes. More recent standards have dropped that requirement as such POTS installations are becoming less and less prevalent.

--- End quote ---
So ok, initially T568A was preferrred for compatibility reasons. Was there a motivation to start preferring instead T568B when the recommandation for POTS was dropped, if it became the most common standard?

Veteran68:

--- Quote from: wraper on August 28, 2023, 12:25:58 pm ---
--- Quote from: Veteran68 on August 28, 2023, 12:20:54 pm ---You could make up your own color scheme and keep it the same on both ends and it would work, though you'd still want to be sure to separate the RX pair to minimize crosstalk interference. However it would for sure annoy the next network technician or electrician to come along and try to figure out what's going on from a visual inspection of the cable. The standards are easily recognizable by experienced installers.

--- End quote ---
You can swap colors but allocation of twisted pairs must remain exactly the same, otherwise it won't work.

--- End quote ---

Well, define "work." :)  The pairs are only twisted for noise mitigation. So up to a certain length, speed, and noise level it would likely work whether the pairs were split or not. You probably wouldn't get reliable 1000Mbps+ out of it, but 10-100Mbps could work over short distances (as in patch cables) as long as all colors were carried straight through.


--- Quote from: bitwelder on August 28, 2023, 12:36:07 pm ---
--- Quote from: Veteran68 on August 28, 2023, 12:20:54 pm ---
T568A was preferred (and initially standardized by ANSI) years ago for construction due to backwards compatibility with common POTS wiring for phones and faxes. More recent standards have dropped that requirement as such POTS installations are becoming less and less prevalent.

--- End quote ---
So ok, initially T568A was preferrred for compatibility reasons. Was there a motivation to start preferring instead T568B when the recommandation for POTS was dropped, if it became the most common standard?

--- End quote ---

Honestly I'm not sure why the preference changed. I remember reading some time ago about the T568A compatibility reasons, but not why over time people seemed to intentionally move to T568B.  A quick Google came up with this article that mentions the initial logic behind T568A but not the reason for the switch.

https://www.truecable.com/blogs/cable-academy/t568a-vs-t568b


--- Quote ---As of 2018, ANSI/TIA still recommends T568A for residential installations for plug-in backward compatibility with old technology like fax machines or a plug-in base station for wireless phone handsets. If you are not using any such devices, or have no intention of plugging ancient RJ11 plugs into RJ45 wall jacks like you would a “phone jack”, then it comes back to personal preference again. In reality, just how many people are using this old equipment any longer? I personally switched over to cell phones in 2006 and have not looked back. 

In the past, specifically with the old TIA/EIA 568-B-2 revision written and ratified around 2001, this recommendation was different for commercial and US government spaces. TIA recommended T568A at that time and further notated US government contracts require T568A. This was to maintain backward compatibility with older equipment like in the residential space (fax machines, etc.) As of the “D” revision, this is no longer the case and that recommendation and notation have been removed. The ANSI/TIA 568.2-D commercial standard is now mute on the subject unless you have a contractual or technical reason to go with one or the other. There is a warning in the commercial standard about making certain that both ends of the cable are terminated to the same scheme. In other words, pick one and stick with it.
--- End quote ---

EDIT: Now that I think about it (obviously I haven't up to this point, LOL), I'm not sure why a RJ11 POTS connection wouldn't be compatible with either standard. RJ11 only used the middle two conductors, both of which are the same blue pair in T568A and T568B? RJ14 added the outer two conductors which are the orange pair on T568B and the green pair in T568A, but as long as both ends of the building wiring were terminated that way it should still work, I would think.

wraper:

--- Quote from: Veteran68 on August 28, 2023, 12:52:54 pm ---
--- Quote from: wraper on August 28, 2023, 12:25:58 pm ---
--- Quote from: Veteran68 on August 28, 2023, 12:20:54 pm ---You could make up your own color scheme and keep it the same on both ends and it would work, though you'd still want to be sure to separate the RX pair to minimize crosstalk interference. However it would for sure annoy the next network technician or electrician to come along and try to figure out what's going on from a visual inspection of the cable. The standards are easily recognizable by experienced installers.

--- End quote ---
You can swap colors but allocation of twisted pairs must remain exactly the same, otherwise it won't work.

--- End quote ---

Well, define "work." :)  The pairs are only twisted for noise mitigation. So up to a certain length, speed, and noise level it would likely work whether the pairs were split or not. You probably wouldn't get reliable 1000Mbps+ out of it, but 10-100Mbps could work over short distances (as in patch cables) as long as all colors were carried straight through.

--- End quote ---
Have you ever heard about transmission lines and controlled impedance? It will probably work up to meter or two but that's it.

Veteran68:

--- Quote from: wraper on August 28, 2023, 01:12:30 pm ---Have you ever heard about transmission lines and controlled impedance? It will probably work up to meter or two but that's it.

--- End quote ---

Yes I have, and I also stated it would likely work with low bandwidth over short lengths, as in patch cables. I'm not suggesting people do it, I'm simply stating there's nothing "magic" about the color sequence that makes it work. Obviously the twisted pairs are there for a reason and should be used as such.

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