Network Message Switching Techniques

In message switching instead of establishing a dedicated physical connection between source and destination, the message is sent to the nearest directly connected switching node. This node stores the message, checks for errors, select best available route and forwards the message to the next intermediate node. The line becomes free again for other messages, while the process is being continues in some other nodes. Due to the mode of action, this method is also known as store and forward technology.

Where the message hope from node to node to its final destination . each node stores the full message, checks for errors and forward it.

Basic Idea

·        Each node receives and store the message

·        Determine the next leg of the route

·        Queues the messages to go out on that line

Advantages

·        Data rate conversion possible

·        Message priorities can be used, to satisfy the requirements if any

·        Line efficiency is greater.

·        Even under heavy traffic, packets are accepted possibly with a greater delay in delivery.

Packet switching

Circuit switching is less suitable for data and other non-voice transmission.  In the case of non-voice transmission, the line may often idle and its facilities are wasted. Circuit switching is inflexible once circuit has been established that circuits is the path taken by all parts of the transmission whether or not it remains the most efficient available.

In packet switched network, data are transmitted in discrete units pf variable block length called packets. The maximum length of the packet depends on the network. Each packet contains one data part and a header with control information’s. The packets are sent over the network; machine to machine, the packet is stored briefly then routed according to the control information in header. In a packet-switched network, there is no resource reservation; resources are allocated on demand.

Two approaches are used to packet switching that is datagram and virtual circuit approach

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