Circuit Switching
Circuit switching has been the first approach to routing
communication channels between users. The originating user
request the connection establishment with the user signaling.
If the channel is available, it will be established between the
communicating parties for the complete duration of the connection
and remains occupied until either communicating end signals a
Circuit switching has been used in classical POTS (Plain Old
Telephone Service) and ISDN (Integrated Services Digital
Since the channel resource is occupied during the connection even
if there is no traffic between the parties, the circuit switching with
dedicated resources is considered more expensive than routing.