OSI/AS SCF Reference Manual

Glossary
OSI/AS SCF Reference Manual—424121-001
Glossary-7
OSI/FTAM
OSI/FTAM. See Compaq OSI/FTAM.
OSI/MHS. See Compaq OSI/MHS.
OSI/TS. See Compaq OSI/TS.
X25AM Physical Layer. Layer 1 in the Open Systems Interconnection (OSI) Reference
Model. This layer establishes the actual physical connection between the network and
the computer equipment. Protocols at the Physical Layer include rules for the
transmission of bits across the physical medium and rules for connectors and wiring.
Port Access Method (PAM). A Compaq communications subsystem that provides an
independent interface to allow applications access to token-ring or Ethernet local area
networks (LANs) on Himalaya S-series servers. The PAM subsystem provides a port
interface that applications can use by making file-system procedure calls. The PAM
subsystem implements, for LANs, the services of the Data Link Layer
and layers below.
PAM replaces the Tandem LAN Access Method (TLAM) for G06 and later releases.
port address. For X.25 Access Method (X25AM)
lines, the logical port number used to
specify the address of the connection to the X.25 network. For Tandem LAN Access
Method (TLAM) lines (for D4x-series releases) or Port Access Method (PAM) lines (for
G06 and later releases), the address used by TLAM or PAM to specify the address of the
connection to a local area network (LAN) controller.
Presentation Layer. Layer 6 in the Open Systems Interconnection (OSI) Reference Model
.
This layer resolves the differences of varying data formats between systems of different
vendors. It transfers data in a system-independent manner, performing appropriate
conversions at each system as necessary.
presentation selector (PSEL). A logical address in the Presentation Layer
through which
presentation services are made available. A single PSEL can service one or more
connections simultaneously.
presentation service access point (PSAP). A network-unique, physical address in the
Presentation Layer
through which connections are established and maintained. Also
called presentation address.
protocol data unit (PDU). Information delivered as a unit between peer entities that contains
data and/or control and address information.
release token. One of the four types of Session Layer
tokens that are associated with
functional units.
SCF. See Subsystem Control Facility (SCF)
.
sensitive command. A Distributed Systems Management (DSM)
command that can be
issued only by a restricted set of users. For Compaq communications subsystems, the
sensitive commands are those that can change the state or configuration of objects, start
or stop tracing, or change the values of statistics counters. Compare nonsensitive
command.