Comment by direwolf20
7 hours ago
Gigabit Ethernet uses four pairs per direction. It uses the same four pairs in both directions at the same time.
7 hours ago
Gigabit Ethernet uses four pairs per direction. It uses the same four pairs in both directions at the same time.
1000Base-T uses two pairs per direction, actually. It's full duplex. Each port sees two TX and two RX pair.
There are four pair of wires in the cable. If you use all of them for TX, you can't receive.
> There are four pair of wires in the cable. If you use all of them for TX, you can't receive.
No, you absolutely can use them all for transmit and receive at the same time. The device at each end knows what signal it is transmitting, and can remove that from the received signal to identify what has been transmitted by the other end.
This is the magic that made 1000Base-T win out among the candidates for Gige over copper, since it required the lowest signaling frequencies and thus would run better over existing cables.
That's not true. https://en.wikipedia.org/wiki/Gigabit_Ethernet#1000BASE%E2%8...