SNA and TCP/IP on z/OS

In the past, a mainframe backbone network used SNA. With the prevalence of TCP/IP and the introduction of SNA/IP integration technology and additional tools, current mainframe networks are migrating to IP-based networks.

SNA was developed by IBM for the business community. SNA provided industry with a technology that permitted unparalleled business opportunities. What TCP/IP and the Internet were to the public in the 1990s, SNA was to large enterprises in the 1980s. TCP/IP was widely embraced when the Internet came of age because it permitted access to remote data and processing for a relatively small cost. TCP/IP and the Internet resulted in a proliferation of small computers and communications equipment for chat, e-mail, conducting business, and downloading and uploading data.

Large SNA enterprises have recognized the increased business potential of expanding the reach of SNA-hosted data and applications to this proliferation of small computers and communications equipment in customers' homes and small offices.

Note: So, why isn't the Internet running SNA protocols? What happened? The answer is simple: complexity. SNA is a deterministic architecture. It uses a hierarchical method of definitions and leaves very little to chance. Bandwidth, connections, and users all need to be predefined completely, or at least to some degree. Contrast this to IP, in which nothing is predetermined and a large degree of unpredictability exists within bandwidth, connectivity, and usage.