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Introduction
Switched communication networks are ones in which data is routed across many intermediary nodes as it travels from source to destination(see Types of Area Networks). The mechanism through which nodes manipulate or switch data to send it between certain places on a network is called Switching. There are three main methods for switching:
Message Switching is a technique used for transmitting messages between computers or terminals in a telecommunications network. It emerged in the 1950s as an improvement over earlier telegraph networks. Message Switching involved storing and forwarding messages between intermediary nodes until they could be delivered to their destination. It was widely used in the early days of Computer Networks, particularly for military and government communication networks, before the advent of packet switching and the internet.
What is Message Switching?
Message switching is a switching mechanism in which a message is sent in its whole and routed to intermediary nodes where it is stored and delivered.
Before packet switching, message switching was created as an alternative to circuit switching.
End-users interact through message switching by sending and receiving messages that include all of the material to be transferred. Messages are the smallest unit of communication.
Furthermore, the transmitter and recipient are not linked directly.
The Message Switching approach does not establish a dedicated route between the sender and recipient.
Several intermediary nodes transmit data and guarantee that the message reaches its intended recipient.
The destination address of the message is appended to it. Message Switching enables dynamic routing by routing messages via intermediate nodes based on the message's content.
Message switches are configured such that only the most efficient routes are accessible.
Each node stores the whole message before forwarding the message to the next node. This kind of network is known as a store and forward network.
When employing message switching, each message is considered a different object.
How Message Switching Works
Message Routing: Messages are routed from source to destination through a series of intermediate nodes.
Entire Message Transfer: The entire message is transferred from one node to the next until it reaches its destination.
Store-and-Forward: Each intermediate node stores the entire message before forwarding it to the next node in the network.
Connectionless: No dedicated path is established for message transmission; instead, each message is routed independently based on routing decisions made by intermediate nodes.
Suitable for Low-Speed Networks: Message switching is suitable for low-speed networks where message size is relatively small, and delay tolerance is high.
Message Switching vs. Packet Switching
Parameter
Message Switching
Packet Switching
Unit of Transfer
Entire message
Fixed-size packets (packets)
Transfer Mechanism
Store-and-forward
Store-and-forward (in packet switching)
Routing
Based on message destination
Based on packet destination
Overhead
High overhead due to storing and forwarding entire messages
Lower overhead due to smaller packet size
Efficiency
Less efficient for large messages or high-speed networks
More efficient for large networks and high-speed transmission
Delay
Higher delay due to storing and forwarding entire messages
Lower delay due to smaller packet size and parallel processing
Examples
Traditional telecommunication networks
Internet Protocol (IP) networks
Process of Message Switching
In Message Switching, messages are first divided into smaller units known as packets, which are then transmitted over the network to intermediary nodes. At each node, the message is stored and forwarded to the next node until it reaches its destination. This process allows for a more reliable and flexible communication system as the message can take multiple routes to reach its destination, and errors can be corrected at intermediate nodes. However, the message delivery can be slower than other techniques such as circuit switching due to the multiple hops required.
Characteristics of Message Switching
Store and Forward as previously stated, the transmitter and receiver are not directly connected. As a result, intermediate nodes are largely responsible for sending the message to the next node in the network between the sender and the receiver. Consequently, intermediate nodes must have the storage capacity to send the message since any message will only be transmitted if the next node and the link between them are both reachable to connect; otherwise, the message will be stored indefinitely. If a store-and-forward switch has adequate resources and the next node is ready to receive the message, it will forward it. The method is continued until the target computer has received all of the data. As a consequence, the property is referred to as store-and-forward property. Telegraph message switching centers formerly used the store-and-forward feature.
Message Delivery: In Message Switching, all of the data is combined into a single message, then transported from source to destination. Each message must include routing information in its header part to reach its intended destination.
Resource Efficiency: Message switching can be more efficient in terms of bandwidth utilization when compared to circuit switching, especially when there are idle periods in the network. Since messages are stored and forwarded, the network can better use the available resources.
Suitable for Bursty Traffic: Message switching is suitable for bursty traffic patterns where messages are not continuously generated.
Error Handling: Message switching can provide reliable error-checking mechanisms at the switching nodes, allowing for detecting and correcting errors before forwarding.
Delay in Message Switching
In message switching, delay refers to the time taken for a message to travel from the source node to the destination node through intermediate nodes in the network. Several factors contribute to delay in message switching:
Store-and-Forward Mechanism: Each intermediate node in the network stores the entire message before forwarding it to the next node. This introduces delay as the entire message needs to be received before forwarding can begin.
Queueing Delay: If a node is busy processing other messages or if there are congestion issues in the network, the incoming message may need to wait in a queue before being processed and forwarded. Queueing delay adds to the overall delay experienced by the message.
Transmission Delay: Once a node receives the entire message, it needs to transmit the message to the next node in the network. Transmission delay occurs due to the time taken to send the message over the communication medium, which may vary based on factors such as distance and network congestion.
Propagation Delay: Propagation delay refers to the time taken for a signal to travel from the source node to the destination node. This delay is determined by the physical characteristics of the communication medium and the distance between nodes.
Processing Delay: Each node in the network incurs processing delay while examining the message headers, making routing decisions, and performing other tasks related to message switching.
Advantages of Message switching
Data channels are shared across connected devices, allowing for better use of available bandwidth. Because the message is briefly kept in the nodes, traffic congestion may be alleviated.
The message size that is transmitted across the network may be changed. As a result, it can handle data of any scale.
Data channels are shared across network devices in this Switching.
The effective management of traffic is accomplished by giving message priority.
There is an increase in efficiency since a single channel can now handle several messages.
Because we apply the store and forward attribute in this strategy, network traffic congestion is reduced, and any switching node may hold messages until the network is available.
Message Switching allows for the sending of messages of any size.
It uses less bandwidth to transmit the messages and uses less bandwidth than circuit switching. If the next node or connection is not accessible during message switching, the message is stored on the current node.
Disadvantages of Message switching
The following are some of the disadvantages of employing Message Switching:
Message switching requires a considerable amount of capacity throughout the whole network.
Because the storage of messages creates a delay, this technology cannot be employed for real-time applications.
Because processing takes place in every node, message-switched networks are inherently sluggish, leading to poor performance.
Applications of Message Switching
Here are some applications of message switching:
Email: Email messages are sent using message switching. When a user sends an email, the message is broken down into smaller packets and sent to the recipient's email server. The email server then reassembles the packets into the original message.
File Transfer: File transfer protocols such as FTP (File Transfer Protocol) and TFTP (Trivial File Transfer Protocol) use message switching to transfer files between two devices. The file is broken down into smaller packets and sent over the network.
Remote Login: Remote login protocols such as Telnet and SSH (Secure Shell) use message switching to establish a remote connection with another device. The login credentials and other data are sent using message switching.
Instant Messaging: Instant messaging applications such as WhatsApp and Facebook Messenger use message switching to transmit messages between users. The message is broken down into smaller packets and sent over the internet to the recipient's device.
Message switching was historically used for data communication in early telecommunication and telex systems. It's less common today because it has been replaced by more efficient packet and circuit switching methods in modern computer networks.
Which layer is message switching?
Message switching does not fit into the OSI model's seven layers. It operates at a higher level, and it is primarily concerned with transferring complete messages rather than packets or frames.
Conclusion
In this article, you learned about Message Switching in Computer Networking. We discussed the history, process, and characteristics of message switching, along with its advantages and disadvantages. We also looked at some applications of message switching.
I hope that you have gained some insight into this topic of message switching.