# Message Switching ## What is Message Switching Message switching is a data transmission technique in which the entire message is transmitted from the source to an intermediate node, stored at that node, and then forwarded to the next node toward the destination when a link becomes available. This process of receiving, storing, and forwarding continues at each intermediate node until the message reaches its final destination. Message switching is sometimes called store-and-forward switching. It was used in early telegraph and telex networks and was a predecessor to packet switching. ## How Message Switching Works The sender transmits the complete message to the first intermediate node in the network. The intermediate node receives the entire message and stores it in its memory or disk storage. The node examines the destination address and waits until a suitable outgoing link is available. When a link becomes available the node forwards the entire message to the next intermediate node. This process repeats at each node along the path until the message reaches the destination. ## Characteristics of Message Switching Message switching does not require a dedicated circuit between source and destination. The network resources are used only when data is actually being transmitted. Messages can be stored at intermediate nodes if the next link is busy, and forwarded when capacity becomes available. This makes message switching suitable for handling bursty traffic and for situations where immediate delivery is not required. ## Advantages of Message Switching Message switching allows efficient use of network resources because links are shared among multiple messages. Messages can be delivered even if the destination is temporarily unavailable because they can be stored at intermediate nodes until the destination is ready. Message switching can handle messages of any length. Priority handling can be implemented so that high-priority messages are forwarded before lower-priority ones. ## Disadvantages of Message Switching Message switching introduces very long delays because the entire message must be received and stored at each intermediate node before it can be forwarded. For long messages and multiple hops the total delay can be very large. Intermediate nodes must have sufficient storage to buffer messages, which was a significant limitation with early computing systems. Message switching is not suitable for real-time applications. Large messages can block the link for extended periods while being forwarded, preventing smaller time-sensitive messages from being transmitted. ## Message Switching vs Packet Switching Packet switching was developed to overcome the limitations of message switching. By dividing messages into small packets, packet switching reduces the delay at each hop because a node does not have to wait to receive the entire message before beginning to forward it. Packets from multiple communications can be interleaved on the same link, reducing the blocking effect of large messages. The delay in packet switching is much lower than in message switching for the same amount of data.