A link is a dual simplex (Simultaneous bidirectional) transmission path between a pair of network elements, such as nodes (HCAs or TCAs) or switches. Link hardware is specified as dual-simplex which mean that send and receive wires each have their own grounds and transmit data unidirectional and independently. The more common simultaneous bidirectional method is “full-duplex.” In full-duplex hardware, both paths share a ground wire. Telephones are full-duplex while two-way radios (“walkie-talkies”) are wireless half-duplex, with one “talker” at a time.