In 1974 IBM announced Systems Network Architecture (SNA), a proprietary networking protocol for computing systems. SNA was a uniform set of rules and procedures for computer communications to free computer users from the technical complexities of communicating through local, national, and international computer networks.
"SNA is still used extensively in banks and other financial transaction networks, as well as in many government agencies. While IBM is still providing support for SNA, one of the primary pieces of hardware, the
3745/3746 communications controller, has been withdrawn from the market by IBM. There are an estimated 20,000
[when?] of these controllers installed however, and IBM continues to provide hardware maintenance service and microcode features to support users. A robust market of smaller companies continues to provide the 3745/3746, features, parts and service. VTAM is also supported by IBM, as is the
IBM Network Control Program (NCP) required by the 3745/3746 controllers.
"In 2008 an IBM publication said:
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"with the popularity and growth of TCP/IP, SNA is changing from being a true network architecture to being what could be termed an "application and application access architecture." In other words, there are many applications that still need to communicate in SNA, but the required SNA protocols are carried over the network by IP" (Wikipedia article on Systems Network Architecture, accessed 9-2020).
Jeremy Norman’s