Parallel Detection

A process that will automatically kicked in if Autonegotation fail. Basically it will try sending signal to the: 10Base-T, 100Base-TX and 100Base-T4 drivers.

If any of these driver receives the signal, the speed is set to that process

10Base-T

10Base-T does not support full-duplex. Some implementation has full duplex but many does not have

100 Base-T

Does support full-duplex. However the default behavior is often setup to be half-duplex. For full-duplex you must set manually

1000Base-T

Has much more robust Autonegotation protocol. Gigabit interfaces should be left to Autonegotation most situation

[!important]
Because 10 Base-T and 100 Base-T is not fully supported full-duplex. Therefore if autonegotiation fail, the safest thing is to choose half-duplex for both