Circuit switch versus Packet switch mechanism

Circuit switching
* Middle routers must presetup the link to transmit the data between two different DTEs
* Circuit-switched networks require dedicated point-to-point connections during calls.
* Data will arrive with constant bandwidth and at constant delay.
* example include Public Switch Telephone Network (PSTN)


Packet switching
* No need to presetup the link to transmit the data between two different DTEs. Data will go ahead from the source DTE to the destination DTE by using the store-and-forward mechanism in all the middle routers
* Pakcet-switched networks don't require dedicated point-to-point connections during calls.
* No predetermined path
* Data will not guarantee with constant bandwidth and constant delay. The communication may suffer from variable bit rate and delay, due to varying traffic load and packet queue lengths
* Include connection-oriented (known as virtual-circuit, described as stateful.) and connectionless (described as stateless)
* examples include TCP, X.25, Frame Relay, GPRS
* Virtual circuit switching technologies include ATM (use VCI/VPI in the cell header), MPLS