Is the current wired Ethernet half-duplex the same as the early Ethernet half-duplex?

心☆野

Is the current wired Ethernet half-duplex the same as the early Ethernet half-duplex? [Copy link]

I've recently been working on a cost-reduction project that uses half-duplex mode in wired Ethernet. I searched online for related discussions and found most of the same opinions: "In half-duplex mode, transmission and reception are on the same line, and the CSMA/mechanism is needed to implement carrier sensing and collision detection."

The Ethernet cables we commonly use currently all have four pairs of differential lines. In 100M full-duplex mode, only two pairs are actually used. So if the PHY is configured in 100M half-duplex mode, will only one pair of differential lines be used?

However, in my actual test, I found that two pairs of differential lines must be connected to achieve 100M half-duplex communication. Disconnecting any line will not work. So is it true that the current 100M Ethernet half-duplex actually uses two pairs of differential lines, one pair for sending and one pair for receiving? But the PHY does not allow simultaneous sending and receiving. If there is simultaneous sending and receiving, it will report the conflict detection to the MAC layer? Welcome to discuss! !

qwqwqw2088

Because the original poster is talking about 100M network, if it is full-duplex, one line is received and one line is sent, and two differential lines are one group of receiving and one group of sending.
If it is half-duplex, one group of differential lines, half-duplex can only receive or send at the same time.

PHY is just a physical layer device and an interface of the data link layer. Specifically, PHY is a standard module defined in IEEE802.3.

Here is 100M, so follow the 100 protocol

qwqwqw2088

If it is Gigabit Ethernet, there are four pairs of wires, with four data streams in each direction.

You need to configure the PHY port according to the Gigabit optical port (1000BASE-X)

心☆野

qwqwqw2088 posted on 2020-2-17 16:20 Because the OP is talking about 100M network, if it is full-duplex, one line is for receiving and one line is for sending, and two-line differential is one group for receiving and one group for sending. If it is half-duplex, one group...

Does it mean that no matter it is full-duplex or half-duplex, 100M wired Ethernet uses two pairs of differential lines? I think the person who knows this question directly is the PHY manufacturer, but because I chose a domestic PHY, the domestic PHY manufacturer gave me very little support, so I don't know whether they designed their own PHY.