0

since both NLP/FLP and preamble are using predefined pulses, can we use autonegotiation as a way of sync clock, so we don't need preamble anymore?

1

That can't work.

Autonegotiation FLPs do not provide enough transitions to synchronize a bit stream. The pulse width is just 100 ns equiv. to 10 MHz, insufficient to synchronize the physical layer clocks for 100BASE-TX or 1000BASE-T (or even xGBASE-T). Clock pulses are spaced apart 125±14 µs, too long and too vague for syncing anything.

Additionally, a preamble in front of each frame resynchronizes the bit clock at regular intervals, unlike FLPs which are only used for bringing a link up. (10BASE-T NLPs are only transmitted when there's no data carrier.)

| improve this answer | |

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.