Let me see if I can make this very simple. I may get a stern talking to by the networking pros but here is how I keep it straight.
HALF DUPLEX – I like talking on a CB Radio. Only one person can talk at a time. When I send out my voice no one else can send to me. So the traffic is always one way, which over time can be slow.
FULL DUPLEX – Is more like a phone call. You can both talk and hear all of he conversation at the same time. It gives you two way traffic and is faster then HALF.
Sometimes older printer will only run in Half while I think everything out there that is made int he last 5 or so years is FULL.
What determines whether or not the network is half or full duplex is the equiptment on the network. Is the equiptment supports full duplex then full duplex should be used. If the equiptment only supports half duplex then half duplex should be used.