Packet-switched and circuit-switched networks use two different technologies for sending messages and data from one point to another.
Each have their advantages and disadvantages depending on what you are trying to do.
Difference between circuit switching and packet switching:
Message is broken up into segments (packets).
Each packet carries the identification of the intended recipient, data used to assist in data correction and the position of the packet in the sequence.
Each packet is treated individually by the switching centre and may be sent to the destination by a totally different route to all the others.
It is easier to double the capacity of a packet switched network than a circuit network – a circuit network is heavily dependent on the number of channel available.
It is cheaper to expand a packet switching system.
Circuit-switched technologies, which take four times as long to double their performance/cost, force ISPs to buy that many more boxes to keep up. This is why everyone is looking for ways to get Internet traffic off the telephone network. The alternative of building up the telephone network to satisfy the demand growth is economically out of the question. The battle between circuit and packet technologies has been around a long time, and it is starting to be like the old story of the tortoise and the hare. In this case, the hare is circuit switching—fast, reliable and smart. The hare starts out fast and keeps a steady pace, while the tortoise starts slow but manages to double his speed every 100 meters.
If the race is longer than 2 km, the power of compounding favours the tortoise.
Bandwidth used to full potential
Devices of different speeds can communicate
Not affected by line failure (rediverts signal)
Availability – do not have to wait for a direct connection to become available
During a crisis or disaster, when the public telephone network might stop working, e-mails and texts can still be sent via packet switching
Under heavy use there can be a delay
Data packets can get lost or become corrupted
Protocols are needed for a reliable transfer
Not so good for some types data streams e.g real-time video streams can lose frames due to the way packets arrive out of sequence.
Circuit is dedicated to the call – no interference, no sharing
Guaranteed the full bandwidth for the duration of the call
Guaranteed Quality of Service
Inefficient – the equipment may be unused for a lot of the call, if no data is being sent, the dedicated line still remains open
Takes a relatively long time to set up the circuit
During a crisis or disaster, the network may become unstable or unavailable.
It was primarily developed for voice traffic rather than data traffic.www.teach-ict.com/.../circuit_and_packet_switching.ppt