IPVMU Certified | 01/22/15 03:12am
Some of the hard questions in life I've come to understand, or at least accept:
- Why we use QWERTY keyboards to type when it is the worst layout imaginable,
- Why Windows uses a backslash and Unix uses a slash, for the same thing (e.g. subdirectories), leading to untold instability, endless debugging and systemic confusion, ever since they were first introduced to each other on the WWW.
- Why every single cell phone battery ever owned by my family (30+) is incompatible with every phone but one, even though looking and being rated much the same.
But why the 10Base-T RJ-45 jack pin assignments ended up so 'twisted' is still a mystery to me.
Specifically, what is the real reason that one of the pairs (the green in 568B) gets split around another, (the blue)? Making the task much more error prone and far more time consuming than need be.
Consider how much easier the task would be if each pair were assigned consecutively say orange 1-2, green 3-4, blue 5-6, brown 7-8. So much less untwisting would be required, pairs would stay together and would naturally end up on the right pin by default. Cross talk would be reduced.
Question 1: Wouldn't the time to terminate ends drop by half at least, if they were consecutively laid out?
Question 2: Is there a valid electrical reason for the present day arrangement?
Question 2: If not was there a valid procedural advantage to this arrangement?
Note: I understand some of the historical reason for this, namely the USOC convention of starting the pairs from the middle and working out, but it seems that was abandoned because the distance between pairs was too great for the last 2. But if they knew that why didn't they just lay them out all consecutively at that point? Also, I'm aware that they were just defining another standard, just like the many thousands already defined, and could not predict the future impact of their decision then.
Maybe a resident cabling God/Icon knows? :)