Circuit switching and packet switching are 2 of the 3 categories in which switching is classified. The significant difference between circuit and packet switching lies in the approach used for the purpose of transferring between various networks. In circuit switching a proper channel between the source and destination is maintained through which transfer of data in one go takes place. As against, in packet switching there exists no dedicated path for data transmission as data is randomly transmitted to the destination through multiple paths.
In circuit switching, the data is not divided into units so the complete data is to be transmitted through the same route. However, in packet switching data is fragmented into separate bundles and each bundle is allowed to take separate paths in order to reach the destination.
What is Switching?
A technique by which interconnection between various networks or components of a network is established is referred to as switching. The mechanism of switching allows the transmission and reception of information between various computer networks efficiently. Through switching end to end, digital connectivity is maintained between the networks that helps in transmitting the data and voice signals simultaneously over the channels that connect the various nodes.
On the basis of the approach utilized for data transmission between source and destination, switching is majorly classified as:
- Circuit Switching
- Message Switching
- Packet Switching
- Datagram switching
- Virtual Circuit switching
Here in this content, we will focus on the differentiating factors between circuit and packet switching.
Content: Circuit Switching Vs Packet Switching
|Basis for Comparison||Circuit Switching||Packet Switching|
|Basic||A connection-oriented approach.||A connectionless approach.|
|Data transmission and reception||In various units as a complete message.||In the form of various separate packets.|
|Execution||A connection is made through which data is transmitted and after transmission the connection is detached.||No direct connection is made and the data in the form of packets is transmitted randomly through various paths.|
|Processing of data||Only at the source location.||At the source as well as intermediary nodes.|
|Suitability||In large message transmission.||In small messages transmission.|
|Type of transmission||Sequential||Non sequential|
|Implementation||Physical layer||Network layer|
|Delivery protocols||Simple||Comparatively complex|
|Data Congestion||May arise while establishing channel.||May occur during transferring of packets.|
|Delay between data units||Constant||Variable|
|Installation cost||Low||Comparatively high|
|Cost dependency||On distance between source and destination.||On the traffic between source and destination.|
|Bandwidth reservation||Exist||Not exist|
|Technology||Not save and redirect||Save and redirect|
|Advantages||Offers continuous and long distance transmission.||Offers immunity towards network failure.|
|Disadvantages||High bandwidth requirement||Complex structure|
|Applications||Voice communication||Data transmission|
Definition of Circuit Switching
Circuit switching is a connection-oriented approach of transferring the data units from one end to another across a network. This approach of data transmission is a three-step procedure that includes connection making, data transferring, and connection removing.
This works in a way that initially a physical path between the source and destination is to be established. This is achieved like each preceding node sends a connection request to its succeeding node till the time a connection between the source and destination nodes is made.
Once the connection is established then through that physical path data is transferred between source and destination. Further, after the completion of data transfer, the circuit connecting source and destination is disconnected by sending, clear request packet.
Mainly public telephone networks utilize circuit switching.
A major drawback of circuit switching is that in case of failure whole circuit or connection must be required to rebuild.
Definition of Packet Switching
Packet switching refers to a technique where the complete information is divided into multiple units where these units are called packets and the packets travel from source to destination by taking different paths. In this approach, no specific direct connection between source and destination is maintained through the nodes.
More simply, we can say, here the message is broken into small bundles of variable lengths and each specific bundle is transmitted through different routes and the selection of the routes depends on the efficiency of the available route.
Packet switching is mainly classified as virtual circuit switching and datagram switching.
Virtual circuit switching is a connection-oriented technique of packet switching in which a virtual connection is first made between the source and destination and the packets then routed along this path. Basically what happens here is each data packet holds a sequence number by which the collected packets at the receiver get sequenced.
It is to be noted here that once the virtual path is maintained then the packet header will not have the address information however it may have information related to the length and timestamp of the packet.
Now, the other approach is datagram switching, which is a connectionless technique in which each packet acts as an individual unit containing the source and destination address along with the sequence number. In the datagram approach, packets of the same message may opt for different routes, and the routing is dynamically decided by the nodes.
Due to this reason, it is not necessary that every time the packets of a single message will arrive in a sequential manner at the destination. However, the receiver has the knowledge of the correct sequence of the packets and after getting all the packets the receiver arranges them sequentially.
Key Difference Between Circuit and Packet Switching
- The major difference between circuit and packet switching is that in circuit switching the transmission of the information is attained by maintaining a connection between the source and destination and through that specific path the signal is transferred. Once the information is received then the connection between the two ends is detached. However, this is not the case with packet switching because in packet switching the information in the form of various packets is transmitted between source and destination by various paths and is collected at the destination. Thus, here no specific channel is required for transmission to take place.
- Circuit switching majorly takes place in the physical layer while packet switching is achieved in the network layer of the OSI model.
- In circuit switching the available bandwidth is fixed as the complete signal is transmitted through one channel. However, packet switching uses dynamic bandwidth utilization where the bandwidth varies according to the path taken by the packets to reach the desired destination.
- Circuit switching is regarded as quite inefficient in comparison to packet switching due to the fact that in circuit switching the bandwidth from source to destination is reserved by making an initial connection without the idea that whether that particular connection is in continuous use or not. While packet switching is considered as more efficient as here no such pre connections are made and packets are independently transmitted by taking various paths to reach the destination.
- Although each unit of the message is transmitted through a common path in circuit switching the information is not stored by each of the nodes present within the source and destination as it never functions in the save and redirect approach. As against, packet switching adopts the save and redirect method where each packet is forwarded according to the routing decisions of the intermediary nodes.
- The cost of the circuit switching method relies on the distance between sender and receiver as the connection is required to be built between them. Whereas the cost of packet switching is dependent on the traffic between source and destination because various packets are taking multiple paths to reach the destination.
- Circuit switching offers data processing only at the source while packet switching offers data processing at each intermediate node from where the packets are traveling to reach the destination.
- In circuit switching, the delay between different units of information is constant whereas the delay between the packets in case of packet switching is variable.
- Circuit switching offers comparatively simple delivery protocols than packet switching.
- Circuit switching is advantageous in terms of long-distance transmission while packet switching is advantageous in terms of immunity towards network failure due to flexible routes.
- The disadvantages offered by circuit switching and packet switching are high bandwidth requirement and complexity in structure respectively.
Thus, this discussion concludes that the two methods of switching offer the data and information to be transmitted network-wide in the form of separate units. But due to the approach used for the transmission, circuit switching shows suitability in applications where voice signals are required to be transferred while packet switching is suitable for the applications where data is required to be transmitted.