OSI/TS Configuration and Management Manual

Glossary
OSI/TS Configuration and Management Manual—424831-001
Glossary-12
State-machine error.
State-machine error. (1) In the programmatic interface to OSI/AS, an error caused by an
applications making an APS procedure call that invokes a primitive at the wrong time or
under the wrong conditions.
(2) In the event-management interface to OSI/AS, an internal error in the OSI/AS
software that causes the TAPS process to issue an event message.
Station group address. A media access control (MAC) address, common to the same type
of system (that is, intermediate systems or end systems), that is used by a system to
broadcast to all systems of the same type (that is, intermediate systems or end systems).
Subdevice. A logical entity providing access to a physical that is, to a communications line.
There may be one or many subdevices associated with a given line or process. Exactly
what constitutes a subdevice differs depending on the subsystem. An OSI/AS (TAPS)
subdevice is created dynamically by the OSI manager process when a connection is
made and usually lasts only as long as the connection exists. An OSI/TS (TSP)
subdevice is a Guardian 90 subdevice that uniquely identifies a Transport Layer
connection; it can be dynamically created and deleted or it can be reused after the
connection is released. An X25AM subdevice corresponds to an X.25 virtual circuit.
TLAM subdevices are of several types: FSAPs, ports, services, domains, workstations,
windows, and gateways (for G06 and above release, PAM subdevices corresponds to an
PAM ports).
Subnetwork dependent convergence function. See SNDCF (subnetwork dependent
convergence function).
Subnetwork. One or more intermediate systems that provide relaying and through which
end open systems may establish network connections.
Subsystem. (1) The software and/or hardware facilities that provide users with access to a
set of communications services.
(2) In 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 interface.
Subsystem Control Facility. See SCF (Subsystem Control Facility).
SCP (Subsystem Control Point). In DSM, the management process for all Compaq 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.
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 Compaq), a subsystem number that identifies that particular subsystem, and a