4

In 10BASE-T and 100BASE-TX Ethernet over twisted-pair cable(for example Cat5e, Cat6a) on PHY level the signals of two endpoints are connected as follows:

Tx+ <--> Rx+
Tx- <--> Rx-
Rx+ <--> Tx+
Rx- <--> Tx-

This might be a bit of an electrical engineering question, but why there are two Tx signals(obviously two Rx at the receiving end)? If data is transmitted at the same time over Tx+ and Tx-, then does this mean that Ethernet on PHY level is a parallel connection?

  • Do you have an extra 0 in 1000BASE-TX? Nobody really uses that. – Fizz Dec 1 '15 at 23:55
7

why there are two Tx signals(obviously two Rx at the receiving end)?

It is for differential signalling to increase noise immunity.

If data is transmitted at the same time over Tx+ and Tx-, then does this mean that Ethernet on PHY level is a parallel connection?

It is not parallel within a single pair; parallel data transfer involves multiple bit streams. 10/100m Ethernet doesn't leverage parallel data transfer.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.