RJ45 connector crimping... Does it really make a difference as long as the cabling is "straight"?

Question

Yes I am aware that there are standards on how to crimp a RJ45 connector. But my question is... does it really make a difference as long as both ends have the same color coding? Technically, it appears that it should not. When I tried, any color combination, as long as it was the same at both ends, it worked, as expected. True that if everyone followed their own standards, it would be difficult to just recrimp one end without knowing how the other-end was crimped (in the absence of a standard). I was wondering why the green twisted pair is spread apart in the standard? Makes the crimping a bit clumsy...

Answer 1

It depends on what you're using the cable for. If you're using it for any flavor of Ethernet (10/100/1000BASE-T), then Yes, it makes a difference for signal integrity.

Ethernet uses differential signaling, where a signal waveform is sent down one wire of each pair, and the inverse of that signal is sent down the other wire of that pair. Because the two wires of the pair are kept so close together by the twisting, each wire is equally exposed to any interference. At the receiver, the inverse signal (with interference) is inverted again and combined with the normal signal (with interference) from the other wire. This causes the interference to be canceled out, while the signal is reinforced.

If you don't get the twisted pairings right, the wires will be exposed to different levels of interference, so the cancellation won't work as well. This can make a difference for longer runs through more interference-prone environments (past lots of other cables and electrical/electronic equipment), and at higher speeds.

People ask questions on here all the time about why their long gigabit Ethernet run isn't working, and the solution is often that they got the pinout right, but didn't get the twisted pairings right.

So yes, make sure pins 3&6 are a twisted pair, etc.