HP-UX SNAplus2 R7 General Information

SNA Networking
Components of a Subarea Network
A diagram of a subarea network looks like an inverted tree, as shown in Figure 1–1, SNA Subarea Network.
Figure 1–1 SNA Subarea Network
Terminal
Controllers
Printer
Printers, Terminals
and Other Devices
Controller
Host
FEPs (Communications
Controllers)
Communication
Links
Controller
Printer
The root of the tree (at the top of the diagram) is the host computer that controls the network. The branches are
the communications links. The leaves (at the bottom of the diagram) are the terminals or printers attached to the
network and accessed by users.
The traditional subarea SNA setup described here enables users to access the resources of a single host system. The
terminals provide only simple data entry and display functions to and from the terminal controller. The terminal
controller is responsible for handling SNA communications between the terminals and the host.
The terminal controller and its terminals can be replaced by an SNA product such as SNAplus2. From the host’s
point of view, SNAplus2 appears as a terminal controller. However, it provides the users with additional functions,
such as the ability to access more than one host system and facilities for customizing screen displays. In addition,
SNAplus2 runs on HP-UX computers that can also be used for other tasks not related to SNA (unlike the terminal
controller, which is used solely for communications with the host).
1.1.1 Subarea SNA Node Components
This section describes the logical SNA components in a subarea network.
The host node contains the following elements:
SSCP
The host node contains a system services control point (SSCP) that is responsible for managing network
resources. Its jobs include activating and deactivating sessions between host and remote components.
The SSCP also provides an interface to network operators at the host system, who can inspect and control
resources in the network.
Logical Units (LUs)
The host node also contains LUs. On the host, each LU provides an access point to the network for an
application.
Communication sessions are maintained between host LUs and the LUs on remote devices, to enable remote
end-users to communicate with host-based applications.
At the remote end of the communications link, the node in the terminal controller contains the following logical
elements to help control communications with the resources on the host:
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