Is telephone and 10/100 MBps LAN wiring electrically symmetrical? I mean is it allowed to swap wires in the pairs, or is one of them like GND so they cannot be swapped? It's important to know when I plan longer wires if I can use just two wires of the same color.
I am unable to find some information on how telephone and 10/100Mbps LAN communication works on this physical layer because I don't know the correct technical terms I should search for.
(I am not talking about symmetrical speed of digital lines.)
Best Answer
You cannot swap wires in the pairs for either, but for different reasons.
In telephony, the AC voice signal is overlayed on a DC supply, which is used to power telephones. Research starting point would be hybrid. If you filtered out the DC part, and only transmit the AC part, you could actually swap the wires.
In 10/100 Mbit/s LAN you cannot swap the wires, because the signal on the wires is differential, the signal of the second wire gets subtracted from the signal on the first wire. If you switch the wire, you reverse the polarity of the signal, effectively munging the bits. Start out here: physical layer