In this article, we have explored different types of Network Switching in Computer Network. These include types like Circuit Switching, Message Switching and others.
Table of contents:
- Introduction to Network Switching in Computer Network
- Circuit Switching
- Message Switching
- Packet Switching
Introduction to Network Switching in Computer Network
A switched network is made up of a collection of interconnected nodes known as switches. Switches are devices that may establish temporary connections between two or more devices that are attached to the switch. Some of these nodes are connected to the end devices in a switched network. Others are solely used for routing.
Switching is the process of transmitting packets from one port to another that leads to the destination.
Note that, every switch is linked to more than one nodes.
Generally, there are three switching techniques:
- Circuit Switching
- Message Switching
- Packet Switching
1. Circuit Switching
A circuit-switched network is made up of a series of switches linked together by physical connections, each of which is split into n channels. Circuit switching occurs at the physical layer.
Before beginning communication, the stations must reserve the resources that will be needed during the communication. These resources, which include channels(bandwidth in Frequency Division Multiplexing and time slots in Time Division Multiplexing), switch buffers, switch processing time, and switch input/output ports, must be allocated throughout the data transfer process until the breakdown phase.
Data sent between the two stations is not packetized (physical layer signal transmission). The data are a constant flow supplied by the source station and received by the destination station, but there may be intervals of inactivity. During data transfer, there is no addressing. The data is routed by the switches based on their occupied band (FDM) or time slot (TDM). Of course, end-to-end addressing is employed throughout the setup phase.
In a circuit-switched network, communication occurs in three stages:
1. Connection Setup Phase
A dedicated circuit (combination of channels in connections) must be established before the two parties (or many participants in a teleconference) may interact. Because the end systems are generally linked to the switches through dedicated lines, connection setup entails building dedicated channels between the switches. It should be noted that end-to-end addressing is essential to establish a link between the two end systems.
2. Data Transfer Phase
After the exclusive circuit (channels) are established, the two entities can transfer data.
3. Connection Teardown Phase
When one of the participants has to disconnect, a signal is transmitted to each switch, allowing the resources to be released.
Efficiency of circuit switched network: Circuit-switched networks, it might be claimed, are less efficient than the other two types of networks since resources are distributed throughout the course of the connection. Other connections cannot access these resources.
Delay in circuit switched network: Despite the fact that a circuit-switched network is often inefficient, the latency in this sort of network is negligible. The data are not delayed at each switch during data transfer; the resources are allocated for the lifetime of the connection.
Examples of Circuit-switched networks
Circuit switching is used for long-distance communication links that must be constant for lengthy periods of time. Traditional telephone networks, sometimes known as landlines, are an example of circuit switching technology.
Dial-up transports IP data packets over a circuit-switched telephone network.
Circuit switching is also used in data center networks. To scale traditional data centers and satisfy rising bandwidth needs, optical circuit switching is employed.
Advantages of Circuit Switching
- Only the two endpoints have access to a dedicated communications channel circuit in circuit-switched networks.
- A dedicated circuit connecting two hosts for the lifetime of the connection reduces the possibility of data loss or other dependability issues.
- Because there are only two communication parties on a dedicated channel, circuit-switched networks are more secure than packet-switched networks.
- Once connected, this sort of network typically offers stable connection quality with no data flow delays.
Disadvantages of Circuit Switching
- Circuit-switched networks are only accessible for voice transmission and cannot be used for other sorts of connectivity.
- Network bandwidth is wasted when a circuit is constantly reserved even when it is not in use.
- A dedicated channel is solely for circuit-switched network traffic and cannot be used for anything else. Connections can also fail if there aren't enough dedicated channels.
- A dedicated channel is more expensive per usage.
- Before data can be exchanged, additional time is needed to establish a connection.
2. Message Switching
This method is midway between circuit switching and packet switching. Message switching treats the full message as a data unit and switches/transfers it as whole. A message switching switch initially receives the entire message and buffers it until resources are available to transmit it to the next step. If the following step does not have adequate resources to handle a big message, the message is held and the switch waits.
This method was believed to be a substitute for circuit switching as with circuit switching, the entire route is blocked for only two entities.
Examples of Message Switching
An example of message switching is emails, PC documents, transaction queries and responses.
Advantages of Message Switching
- Because network devices share communication channels, bandwidth use is optimized.
- It aids in minimizing network congestion due by the store and forward approach. Switching nodes can hold messages in the event that a communication link is unavailable, therefore lowering traffic congestion.
- It can transmit messages of any size.
- Unlike packet switching, out-of-order or missing packets have no effect on message switching.
- The sender and receiver's transmission rates do not have to be the same because the message can be cached by the nodes.
Disadvantages of Message Switching
- Every switch in the communication route requires adequate storage to hold the complete message.
- Message switching is highly sluggish due to the store-and-forward approach and the delays included until resources are available.
- Message switching did not work for streaming media or real-time applications.
3. Packet Switching
In packet switching, the entire message is divided into smaller bits known as packets. The switching information is included in the header of each packet and is delivered separately. A packet does not have any resources assigned to it. This indicates that the connections have no allocated bandwidth and no planned processing time for each packet. The allocation of resources is based on the demand. The allocation is done on a first-come, first-served basis.
Small packets are easy for intermediate networking devices to store, because they do not consume a lot of resources, either on the carrier channel or in the internal memory of switches. Packet switching can be divided into two types:
- Virtual Circuit Packet Switching
- Datagram Packet Switching
1. Virtual Circuit Packet Switching
A virtual circuit service is considered to be preferable than a connection-less service in case of lengthy communications. Messages are transmitted in the sequence in which they are sent over virtual circuits, which is similar to telephone service. To construct a circuit, the whole destination and source network addresses, as well as the information necessary to transport a packet, are required.
Once a virtual circuit is constructed, the logical channel numbers enable one of the virtual circuit's DTEs to transfer data to the other. Rather than rejecting packets, network congestion is addressed by restricting the inputs to a virtual circuit (or managing the flow of data).
Individual packets on a virtual circuit are rarely independent; they are usually merely a component of a message.
Advantages of Virtual Circuit Switching
- Because all packets traverse the same path, they are delivered in the same order.
- Because each packet does not need to carry the whole address, shorter headers are needed.
- Because no routing is performed after a call is established, it is faster.
- The connection is more dependable because resources are built up in advance so that even during periods of congestion, if a call has been established, following packets should get through since resources have been set up in advance.
Disadvantages of Virtual Circuit Switching
- Because each switch must keep details of all calls that pass through it, the switching equipment must be more powerful.
- When there is a failure, all virtual circuits must be reconfigured.
2. Datagram Packet Switching
Each packet in a datagram network is processed independent of the others. Even though a packet is part of a multi-packet transfer, the network processes it as if it were a single packet. In this technique, packets are referred to as datagrams. Normally, datagram switching occurs at the network layer.
Connectionless networks are another name for datagram networks. The term "connectionless" refers to the fact that the switch (packet switch) does not maintain track of the connection status. There is no setup or breakdown time. A switch treats every packet the same, regardless of its source or destination.
Routing table: In a datagram network, how are packets routed to their destinations if there are no setup or teardown phases? Each switch (or packet switch) in this form of network has a routing table that is based on the destination address. The routing tables are dynamic and are changed on a regular basis. The tables store the destination addresses as well as the appropriate forwarding output ports. This is in contrast to the table of a circuit switched network, where each item is made when the setup phase is complete and deleted when the takedown phase is complete.
Destination Address: Every packet in a datagram network has a header that includes, among other things, the packet's destination address. When the switch receives the packet, it checks the destination address and consults the routing database to determine which port the packet should be forwarded via. Unlike in a virtual-circuit-switched network, this address remains constant during the packet's trip.
Examples of Packet-switched networks
The Internet is the most well-known example of a packet-switched network that uses the TCP/IP protocol suite. Asynchronous Transfer Mode (ATM) is another packet-switching technology that switches short fixed-length packets called cells between network nodes.
Advantages of Packet Switching
- Because of the flexibility in routing smaller packets over shared lines, it is more efficient.
- Packet switching networks are frequently less expensive to establish since they require less equipment due to sharing.
- Devices of varying speeds can communicate with one another.
- Because destination information is included in each packet, a large number of messages may be transmitted swiftly to a variety of destinations.
- Error detection and correction technologies are used in packet switching.
- Line failure has no effect.
- When the public telephone network goes down due to a crisis or accident, e-mails and SMS can still be transmitted via packet switching.
Disadvantages of Packet Switching
- Longer message delivery times owing to the time necessary to package and transport packets.
- There may be a delay while under severe load.
- Data packets might get damaged or lost.
- Not ideal for some data streams, however extra data compression and quality of service (QoS) technology can be applied to attain the desired performance levels.
- Because of the utilization of shared physical links, there is the possibility of network security vulnerabilities.
With this article at OpenGenus, you must have the complete idea of Types of Network Switching in Computer Network.