HP UX SNAplus2 manual Systems Network Architecture

SNA Terms and Concepts

Systems Network Architecture

Systems Network Architecture

Systems Network Architecture (SNA) is an IBM data communication architecture that specifies common conventions for communicating among a wide variety of hardware and software data communication products. This architecture consists of two kinds of definitions: formats that define the layout of messages exchanged by network components, and protocols that define the actions that network components take in response to messages.

An SNA network is a collection of computers that are linked together and communicate using SNA.

Originally, SNA was designed to enable communications with a host computer. Each network or sub-network was controlled by the host; other computers communicated directly with the host, but not with each other. This older, host-controlled style of network is often referred to as subarea SNA. SNA has since developed to support direct peer-to-peer communications between computers in the network, without requiring a host. This newer, peer-level networking is APPN.

Many SNA networks have elements of both subarea and peer-to-peer networking. As networks migrate from subarea SNA to APPN, an APPN-capable host may act to control older systems while also acting as a peer to newer systems. Similarly, a single computer may access both peer computers (in an APPN network) and an older host; its communications with the host are controlled by the host, but its communications with other computers are peer-to-peer and do not involve the host.

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