TCP/IP Management Programming Manual

Glossary
HP NonStop TCP/IP Management Programming Manual—529636-001
Glossary-17
subnetwork
subnetwork. One or more intermediate systems that provide relaying and through which
end open systems may establish network connections.
Subnetwork Access Protocol (SNAP). In order to run the TCP/IP protocol suite over
IEEE networks, the Subnetwork Access Protocol (SNAP) defines the interface between
the IP layer and the LLC layer. The interface is accomplished through the use of an
extension of the LLC header that contains a predefined Service Access Point (SAP) for
use in the Source SAP (SSAP) and the Destination SAP (DSAP) fields of the LLC
header.
subsystem. (1) The software and/or hardware facilities that provide users with access to a
set of communications service. (2) For DSM, a program or set of processes that
manages a cohesive set of objects. Each subsystem has a process through which
applications can request services by issuing commands defined by that subsystem; in
some cases, this process is the entire subsystem. Many subsystems also have
interactive interfaces.
Subsystem Control Facility (SCF). A part of DSM, used to provide a common, interactive
management interface for configuring, controlling, and collecting information from
Tandem data communications products.
Subsystem Control Point (SCP). .n DSM, the management process for all Tandem data
communications subsystems. There can be several instances of this process.
Applications using SPI send all commands for data communications subsystems to an
instance of this process, which in turn sends the commands on to the manager
processes of the target subsystems. SCP also processes a few commands itself. It
provides security features, version compatibility, support for tracing, and support for
applications implemented as NonStop process pairs. See also management process or
manager process.
Subsystem ID (SSID). In DSM programmatic interfaces, a data structure that uniquely
identifies a subsystem to SPI. It consists of the name of the owner of the subsystem
(such as Tandem), a subsystem number that identifies that particular subsystem, and a
subsystem version number. The subsystem ID is an argument to most of the SPI
procedures.
Subsystem Programmatic Interface (SPI). In DSM, a set of procedures and associated
definition files used to define common message-based programmatic interfaces for
communication between requesters and servers—for instance, in a management
application. SPI includes procedures to build and decode specially formatted
messages; definition files in Pascal, TAL, C, COBOL, and TACL for inclusion in
programs, macros, and routines using the SPI procedures; and definition files in DDL
for programmers writing their own subsystems.
summary state. In DSM interfaces to NonStop data communications subsystems, one of
the generally defined possible conditions of an object, with respect to the management
of that object. A summary state differs from a state in two ways. First, a summary state
pertains to the management of an object, whereas a state may convey other kinds of