The term direct link is used to refer to the transmission path between two devices in which signals propagate directly from transmitter to receiver with no intermediate devices
Point-to-Point
is point-to-point if it provides a direct link between two devices and those are the only two devices sharing the medium.
Multipoint
In a multipoint guided configuration, more than two devices share the same medium.
Simplex transmission
In simplex transmission, signals are transmitted in only one direction; one station is transmitter and the other is receiver.
Half-duplex transmission
In half-duplex transmission, both station may transmit, but only one at a time.
Full-duplex transmission
In this case the medium is carrying signals in both direction
