OSI/FTAM Configuration and Management Manual

Introduction to Tandem FTAM
OSI/FTAM Configuration and Management Manual—421944-001
1-10
OSI/AS, OSI/TS, and TLAM, PAM, X25AM, or
TCP/IP
The following subsections provide a general discussion of the OSI/AS, OSI/TS, and
TLAM (or PAM), X25AM, and TCP/IP subsystems:
•
Tandem Open Systems Interconnection/Application Services (Tandem OSI/AS) on
this page
•
Tandem Open Systems Interconnection/Transport Services (Tandem OSI/TS) on this
page
•
OSI/TS and Tandem NonStop TCP/IP, TLAM (or PAM), and X25AM on page 1-11
Tandem Open Systems Interconnection/Application Services
(Tandem OSI/AS)
The OSI/AS subsystem is a collection of software components that provide OSI Session
Layer and Presentation Layer connections and ACSE (an entity in the Application
Layer) services for Tandem NonStop systems. The processes in the OSI/AS subsystem
that perform communications services are TAPS processes. TAPS processes are
Transport Layer users and providers of session, presentation, and ACSE services. These
processes use the transport connections provided by the TSP processes (through the
OSI/TS subsystem) to establish Session Layer and Presentation Layer connections and
ACSE associations with peer entities.
Each OSI/AS subsystem contains one or more TAPS processes, each of which can
manage many simultaneous connections or associations. All processes in an OSI/AS
subsystem are managed by an OSI manager process. For a detailed description of the
OSI/AS subsystem and TAPS processes, see the OSI/AS Configuration and Management
Manual.
Tandem Open Systems Interconnection/Transport Services
(Tandem OSI/TS)
The OSI/TS subsystem provides OSI lower-layer services to the OSI/AS subsystem,
allowing OSI/AS to establish Transport Layer connections on both wide area networks
(WANs) and local area networks (LANs). Through OSI/AS and OSI/TS, Tandem FTAM
subdevices are translated into distinct transport connections. OSI/TS controls these
connections and guarantees reliable data transfer between computer systems on an OSI
network.
Each OSI/TS subsystem consists of a TSP process. TSP processes manage transport
connections with remote peer entities. TSP processes are network and data-link service
users and transport service providers. These processes use the network services provided
by the NSP processes to build transport connections, and they provide transport services
to the upper-layer (TAPS) processes. For detailed information on the OSI/TS subsystem,
see the OSI/TS Configuration and Management Manual.