Hi zape,
I believe that link alive pulses are mandatory in the TP network (that is, there should be at least one pulse 100ns or packet every 16ms or less). Pre-emphasis is not, because it's funtion is to compensate for the higher frequency components - spectrum of the ethernet signal in the case of the long twisted pair cable, where higher spectrum attenuates more due to the TP cable loss. I guess that you don't need to implement the pre-emphasis and must the link alive pulses circuitry.
If you have two TP NICs (Network Interface Cards) and one AUI, connected to the hub without the collision pair, there should be a problem with the AUI device, because it wouldn't know when the collision happened on the network. Thats the difference of the AUI towards the TP - the AUI has to have an additional circuitry to tell it there is a collision on the network, where the TP interface does it by itself - it knows if the collision happened, if there appears the RX signal while it transmitts on the TX pair already.
But perhaps the AUI would back-off in the case of incoming signal on the RX pair, while it transmitts already on the TX pair (you should try this somehow, but according to the standard, the AUI is not that smart, so it needs a Collision pair).
Full duplex would not work with the AUI, since AUI could step over and not knowing that the collision happend, just as described above. I guess with the low traffic, where there are not many collisions, perhaps it could work nevertheless...
What is that you could do, is to isolate the AUI device to its own network, that is replace the hub with the switch, where everyone has its own communication link. The hub re-transmitts everything that it hears to everywhere, so the AUI has a higher chance creating the collision...
zape said:
Hi rfmw,
I am now working in the 802.3. My question about the link alive, preemphasis was in the way of implementing them was mandatory or optional.
My current main doubt regards the use of the AUI collission lines in case of communication through a hub in a 3 actors network where the communication is full duplex.
Thks for your support