The latest log 108. Error correction over at #miniMAC - Not an Ethernet Transceiver brings an interesting idea for the adjustment of transmission parameters : using a LUT with different GCR patterns, such that the speed is not the only adjustment knob to turn.

The LUT can be hardwired or reprogrammable and contains basic binary patterns (such as tweaked Manchester codes) or ternary (MLT3, 4B3T, 3B2T...)

A link is established with the basic code and frequency increases until the error rate becomes significant, then the GCR LUT is changed to a more efficient one as long as the peer supports it.

I'm not sure yet how to classify the FEC in the pipeline yet, it would be an extra optional layer...