Hierarchical SNA Networks

In the SNA hierarchical model, also called subarea networking, communication begins with the mainframe at the top of the hierarchy and proceeds down the hierarchy to the end user.

Note

In SNA terminology, an end user represents either a person or an application program.

SNA defines several classes of components to support communications between the mainframe, or host system, and the end user.

Hardware Components or Nodes   Hardware that provides the computing platforms and network devices that implement specific SNA communications and management functions.

Connection Types   Hardware and communication standards that provide the data communication paths between components in an SNA network.

Physical Units (PUs)   A combination of hardware and software that provide the configuration support and control of the SNA network devices, connections, and protocols.

Logical Units (LUs)   Protocols that provide a standardized format for delivery of data for specific applications, such as terminal access and printing.

These components provide the basis for IBM SNA. Thus, integrating Windows 2000–based networks and intranets with IBM host systems begins with an understanding of these SNA components. The following sections describe each of these components and how they interact in a hierarchical SNA environment.

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