What are the differences between CAT5E and T568A vs. T568B for ethernet cables?

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Discussion Overview

The discussion revolves around the differences between the T568A and T568B wiring standards for CAT5E Ethernet cables, including their implications for connectivity and potential issues when mixing standards. Participants explore the technical aspects of these standards and their practical applications in networking.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that T568A and T568B standards are functionally transparent to hardware as long as the same standard is used at both ends of a cable run.
  • There are claims that mixing T568A and T568B can lead to various problems, including signal issues and intermittent connectivity, although specific experiences are not universally shared.
  • One participant mentions that T568A is recommended for residential wiring, while T568B is more commonly used in general applications.
  • Another participant explains that using T568A on one end and T568B on the other creates an Ethernet crossover cable, which is used for direct connections between network interface cards (NICs).
  • There is a discussion about the significance of color coding in wiring, with one participant asserting that the colors are irrelevant as long as the correct pinouts are maintained.
  • Technical details regarding the pinouts and signal assignments for the RJ-45 connector are provided, emphasizing the importance of proper termination to reduce electromagnetic interference.

Areas of Agreement / Disagreement

Participants express differing views on the implications of mixing T568A and T568B standards, with some asserting that it can cause issues while others provide examples of successful mixed connections. The discussion remains unresolved regarding the extent and nature of problems that may arise from such mixing.

Contextual Notes

Some claims about the performance and compatibility of T568A and T568B standards depend on specific use cases and may not apply universally. There are also unresolved assumptions regarding the impact of cable gender on connectivity.

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Searching "t568" doesn't bring up any matches: presumably the topic ain't been covered.

As far as stringing ethernet cables, T568A and T568B connector standards for CAT5E are transparent to the hardware being connected so long as one preserves the standard (and gender?) at both ends of a cable run. Net sites discussing A & B include caveats regarding mixing; A won't work with B, and vice versa, with comments that video goes to hell, or other nagging problems, intermittents, sensitivity to phases of the moon, you name it.

The questions: has anyone ever had such problems; and, does anyone know physically what's happening to signals?
 
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OK. thankee.

For the interested, U. S. recommends A for residential wiring, B is the common use item, and B is what you get at the village drugstore when you ask for ethernet patch cords.

A on one end, B on the other, same gender both ends works for tying two computers together.

Hermaphrodites (different genders on ends of cable) are what causes trouble in "mixed" systems.
 
although I don't follow you completely, I would like to specify a couple things that confused me. t568A and t568B are 2 different wiring standards used in cat-5 cable. Normally, t568B wiring is used, but t568a wiring also works.
If you use a cable with t568B on one end and t568A on the other, you'd have
an ethernet crossover cable, used for a NIC2NIC network connection.
I would assume that with just switching the wiring on one end of a cat-5 cable to the other type, you can make a cat-5 cable act as an ethernet crossover cable, however, I have not tried myself (I have used a prefab ethernet crossover cable between 2 NICs and it worked)
 
The colours mean nothing as long as you have the correct pin outs at both ends...

Code: 
100BaseTX RJ-45 Connector

The Fast Ethernet RJ-45 port actively terminates wire pair 4 and 5 and wire pair 7 and 8. Common-mode termination reduces electromagnetic interference (EMI) and susceptibility to common-mode sources.

The table below shows the pin and corresponding signal for the RJ-45 connector pinouts.

RJ-45 Connector Pinout

Pin
	

Signal

1 TX+

2 TX-

3 RX+

6 RX-

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a00801f5d9e.shtml