Message switching

Unlike packet switching, the message is not divided into smaller units and sent independently over the network.

Western Union operated a message switching system, Plan 55-A, for processing telegrams in the 1950s.

[2] Leonard Kleinrock wrote a doctoral thesis at the Massachusetts Institute of Technology in 1962 that analyzed queueing delays in this system.

[3] Message switching was built by Collins Radio Company, Newport Beach, California, during the period 1959–1963 for sale to large airlines, banks and railroads.

[4][5][6] After the seminal meeting at the first ACM Symposium on Operating Systems Principles in October 1967, where Roger Scantlebury presented Donald Davies work and referenced the work of Paul Baran, Larry Roberts incorporated packet switching into the design.

Each message is stored (usually on hard drive due to RAM limitations) before being transmitted to the next switch.

Instead, when the sender has a block of data to be sent, it is stored in the first switching office (i.e. router) then forwarded later one hop at a time.

In a message-switching centre an incoming message is not lost when the required outgoing route is busy.