HP-UX SNAplus2 R7 Administration Guide

SNA Terms and Concepts
Basic SNA Concepts
Note
HP-UX computers running SNAplus2 can function as type 2.1 or type 2.0 nodes.
A type 4 or 5 subarea node to which a peripheral node is attached acts as a boundary node. It performs a boundary
function by translating between the network addresses used by a subarea node and the local addresses used by a
peripheral node.
A simple subarea network includes the following components:
Host
A host is a mainframe computer compatible with the original IBM System/370.
Communication controller
A communication controller, also known as a front-end processor (FEP), is a separate processor attached to
the host. It manages the host’s communications with other computers.
Communications link
A communications link connects the host site with an end-user site. The users are usually on a separate site
from the host, so the two sites need to be connected by a communications link.
Terminal controller
At the remote end of the communications link is a terminal controller, also known as a cluster controller. It
is responsible for controlling the use of the link, and routes data to the terminals. The most well-known IBM
terminal controllers are the 3174 and 3274.
Terminals
Users run host applications or submit work to the host from terminals. The best-known IBM terminal is the
3270. A terminal can be connected through a terminal controller or directly connected to a communication
controller.
Printers
Printers such as the IBM 3287 can also be attached to the terminal controller. They can receive output from
the host.
As shown in Figure 1–1,
SNA Subarea Network, a diagram of a subarea network looks like an inverted tree.
Figure 1–1 SNA Subarea Network
Printer
Printers, Terminals
and Other Devices
Controller
Host
FEPs
(Communications
Controllers)
Terminal
Controllers
Controller
Printer
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