Circuit Switching

Circuit Switching

Circuit Switching take place in Physical Layer.

In this type 2 network nodes establish a dedicated communication channel through the network before the nodes may communicate.

The  circuit guarantees the full bandwidth of the channel and remain connected for the duration of the communication session. The circuit function as if the nodes were physically connected .

In circuit switching a bit delay is constant.

There is no addressing involved during data transfer. The switches route the data based on their banwidth (FDM) or time slot (TDM) , Of course  end to end addressing used during set up phase. 

Three phases of circuit switching are:

1.  Set-up phase :  Connection is established between end points  before any communication. First end send the connection request and the second end send the acknowledgement in this phase.

2.  Data Transfer Phase :  In this phase communication take place.

3.  Tear-down phase : when one of the parties want to disconnect a signal is sent to each switch to leave the resources.

   EFFICIENCY :  This type of switching is not efficient.

   Delay  :  But delay is minimal. There is no waiting time at each switch. Total delay is due to time needed to create connection, transfer data and  and disconnect circuit.

   Uses :

   Plain old telephone system (POTS) uses circuit switching.

   Original GSM is also based on circuit switching. But GPRS introduce packet switching in GSM network.