OSI/FTAM Configuration and Management Manual

Introduction to Tandem FTAM
OSI/FTAM Configuration and Management Manual—421944-001
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OSI/AS, OSI/TS, and TLAM, PAM, X25AM, or
TCP/IP
OSI/TS and Tandem NonStop TCP/IP, TLAM (or PAM), and
X25AM
OSI/TS uses OSI Transport Protocol class 0 while running over TCP/IP, because the
Transport Control Protocol (TCP) itself provides the features of error-recovery, error-
detection, or multiplexing within TCP. The Tandem NonStop TCP/IP subsystem runs on
the Tandem NonStop Kernel operating system over an X25AM or a TLAM (or a PAM
for G-series) input/output (I/O) process. Tandem OSI/TS connects to TCP/IP at the
Transport Layer by specifying TCP/IP as the network service provider (NSP) process.
TCP/IP, in turn, connects to X25AM and TLAM (or PAM for G-series).
The Tandem LAN Access Method (TLAM) subsystem [or the Port Access Method
(PAM) subsystem for G-series] provides Data Link Layer services to the OSI/TS
subsystem for systems that communicate over a local area network (LAN). These
services are provided by TLAM or PAM NSP processes.
The X.25 Access Method (X25AM) subsystem provides Network Layer services to the
OSI/TS subsystem for systems that communicate over an X.25 wide area network
(WAN). These Network Layer services are provided by X25AM NSP processes.
NSP processes run as privileged I/O processes in the NonStop Kernel operating system
environment. Each NSP process is associated with a particular hardware controller
board and controls a particular physical line into the communications subnetwork. Each
line controlled by an NSP process can support multiple simultaneous transport
connections. NSP processes must run in the processors to which the subnetwork
controller boards are attached; the processes are otherwise independent of the location of
other subsystems.
For detailed information on theTandem LAN Access Method (TLAM) subsystem, see
the TLAM Configuration and Management Manual. For detailed information on the
X.25 Access Method (X25AM) subsystem, see the System Generation Manual for
X25AM and the SCF Reference Manual for X25AM. For detailed information on the
Tandem NonStop TCP/IP subsystem, see the TCP/IP Configuration and Management
Manual. For detailed information on the Port Access Method (PAM) subsystem, see the
PAM Configuration and Management Manual.