Difference Between Circuit Switching and Packet Switching

Circuit Switching vs Packet Switching

Circuit Switch (CS) and Packet Switch (PS) are two different types of switching domains to sending information and messages from one point to another. In telecommunication, circuit switching was the first method used to send voice and data. After the evolution of packet switched domain, data portion of communications are separated from circuit switch domain. GPRS and EDGE are the initial stages of packet switched domain evolution. With the release of 3G networks, some of the voice communications initiated to flow through packet switch network, and circuit switching became less important. Circuit switched domain is fully shifted to packet switch by the latest 3GPP releases such as R9 and R10, where all voice communications handled using VoIP services that run on packet switch domain.

What is Circuit Switching?

Circuit switch was initially used in telecommunications, to switch different channels so that people can communicate with each other. In circuit switching, path is decided and dedicated before actual data transmission starts. For the whole length of communication between two end points, bandwidth and other resources are fixed and dedicated, which will only be released when session ends. Due to this dedicated nature of the channels in circuit switch domain, it can provide guaranteed QoS from end to end, which provide more suitability to real time applications such as voice and video. In addition, order of messages sent from the source will not be changed at the destination when it goes via circuit switch network. This also leads to less processing at the destination to regenerate the original message.

What is Packet Switching?

In Packet Switch networks, message gets broken into small data packets, which are sent towards destination irrespective of each other. Path from source to destination is handled by number of protocols, whereas routing of the packets is handled by switching centers or routers. Each packet finds its path depending on the source and destination addresses and ports. Since each packet is treated separately in packet switched networks, packets are labeled in such a way so that the original message can be recreated at the destination even though the packets have not arrived at the destination in the original order they have been sent from the source. packet switch domains should be properly maintained with guaranteed QoS levels in order to carry real time traffic such as voice and video streams.

What is the difference between Circuit Switch and Packet Switch?

Initially, packet switch networks were widely used for data communication and circuit switch networks were used for voice communication. However, improved QoS settings in the packet switch domain attracted the voice communication into the packet switch domain lately. In packet switch networks, bandwidth can be utilized to its full potential, while with the circuit switch networks bandwidth utilization will be less efficient since each communication should have a dedicated bandwidth even it is used or not. Can have more redundancy in packet Switch networks since each packet is routed using its addresses, whereas with circuit switch networks it is predefined.

Packet switch networks can be shared when number of users increase, whereas circuit switch networks are limited by the maximum number of available channels. When utilization exceeds some level, throughput bottlenecks will be visible in packet switch networks, and packets will be delayed, and usage of some real time services will be meaningless. On the other hand, with the circuit switch domain, users cannot exceed the maximum number of connections available in the network. Therefore, required quality for real time applications can be easily maintained within a circuit switch connection. In addition, order of messages sent will not be altered when passing via a circuit switch network, whereas, with packet switch network, there is no such guarantee. Due to this guaranteed and reliable nature of circuit switch domains, processing at source and destination will be much less when compared with the complex algorithms that will be used to recover data in packet switch networks.

Circuit switch networks design itself provides a guaranteed end to end QoS, whereas in packet switch domains QoS need to be implemented. Packet switch domains provide more efficient use of resources due to shared nature in that networks, whereas circuit switch domains are less efficient due to dedicated nature of the network.