Transmission Direction: Simplex, Half-Duplex, and Duplex

                Transmission Direction:
       Simplex, Half-Duplex, and Duplex 
• Simplex transmission: signals may travel in only one direction
• Half-duplex transmission: signals may travel in both directions over a medium
    – Only one direction at a time
• Full-duplex or duplex: signals free to travel in both directions over a medium simultaneously
    – Used on data networks
    – Channel: distinct communication path between nodes
• May be separated logically or physically