OSI/AS Programming Manual

Glossary
056783 Tandem Computers Incorporated Glossary-11
Interface. (1) With respect to the OSI Reference Model, a set of rules by which a given
layer passes information to the adjoining layer below or above.
(2) With respect to Tandem products, a set of rules by which a human operator or a
program interacts with a hardware or software product, such as Tandem OSI/AS.
Intermediate system. Any combination of subnetworks and relay systems used to
connect two or more end systems. Tandem systems are not used as intermediate
systems. See also end system.
International Telegraph and Telephone Consultative Committee. See CCITT.
Invocation identifiers. A pair of values identifying the application entity and application
process at one end of an ACSE connection. Their settings are left up to the application.
IP (OSI internet protocol). An ISO standard that defines communications in the Network
Layer. This term is not to be confused with the internet protocol of TCP/IP, which is a
different protocol.
IPPDU (IP protocol data unit). See PDU.
ISO (International Organization for Standardization). A United Nations organization,
established to promote the development of standards to facilitate the international
exchange of goods and services and to develop mutual cooperation in areas of
intellectual, scientific, technological, and economic activity.
ISO Reference Model for Open Systems Interconnection. See OSI Reference Model.
LAPB (link access protocol - balanced). CCITT standards that define in the Data Link
Layer the requirements for X.25 connections over wide area networks (WANs).
Layer. There are seven layers in the OSI Reference Model. See Application Layer, Data
Link Layer, Network Layer, Physical Layer, Presentation Layer, Session Layer, or
Transport Layer.
LDIB (Local Directory Information Base). See MIB.
LLC (logical link control). An IEEE 802.2 standard for the Data Link Layer of the OSI
Reference Model that defines both connection-oriented and connectionless standards
over LAN networks.
LMIB (Local Management Information Base). See MIB.
Local address. The terms local address and remote address refer to the two endpoints
of a connection. A local address is the address of the end-system which is considered
local with respect to the user.
Loopback connection. For qualifying applications, an improvement in throughput and
performance can be accomplished by using a loopback connection. Data is passed
between the applications only going as far as the TAPS processes, bypassing the TSP
and NSP processes. To be able to use loopback, both applications must use #APPL
entries, use the same OSI manager process, and reside on the same OSI subsystem,
with the called application specifying loopback.