Table 3-5 Ethernet parameters for half duplex mode
In full-duplex operation mode, both transmitting and receiving frames are
processed simultaneously. This doubles the total bandwidth. Full duplex is much
easier than half duplex because it does not involve media contention, collision,
retransmission schedule, padding bits for short frame. The rest functions follow the
specification of IEEE802.3. For example, it must meet the requirement of minimum
inter-frame gap between successive frames and frame format the same as that in
the half-duplex operation.
Because no collision will happen in full-duplex operation, for sure, there is no
mechanism to tell all the involved devices. What will it be if receiving device is busy
and a frame is coming at the same time? Can it use “backpressure” to tell the
source device? A function flow control is introduced in the full-duplex operation.