3. Circuit switching - issues and benefits

Issues:

• Very inefficient - once the connection is made, the line is tied up and no one else can use it, even if no data is being transmitted.
• Can be slow to set up the communication channel.
• Single point of failure - if any part of the channel fails, communication is lost
• Every connection has to be capable of supporting the maximum bandwidth required. This was no problem for voice calls as a voice call needs a very low bandwidth (3KHz), but not when bandwidths of 100Mbps + are needed.

Benefits

• A dedicated channel guarantees a continuous connection - a packet switched system has to share channels with other users, quantified by the 'contention ratio' of the line. Circuit switching implies a contention ratio of 1.
• There is no latency. This means no delay in data arriving at the receiver and what is more it is guaranteed to arrive in the right order. Packet switching has latency and packets arrive out-of-order.