Glossary

See Advanced Communication Function for the Network Control Program.

See Advanced Communication Function for the Virtual Telecommunications Access Method.

See Advanced Communication Function.

A state in which part of an SNA node is able to function as it was designed.

A group of IBM program products that uses SNA concepts.

An IBM program product that resides in the 37xx Communications Controller and supports single and multiple domains.

An IBM program product on the host that provides communication access to and from the SNA network for single and multiple domains.

An SNA request sent by the host to activate a session between two logical units. The request specifies the detailed protocol to be accepted before initiating an LU-LU session.

A sequence of RUs constituting a recoverable entity.

See Command Interpreter.

A programmable device that supports one or more terminals or printers. For example, the cluster controller would be the center node in a star shaped cluster network, governing all message traffic to and from the other nodes.

A cluster controller communicates with the communications controller either through a local channel attachment or through modems and phone lines.

The part of MPE which analyzes and processes commands entered during a session or submitted as part of a job.

A type of front-end processor, such as an IBM 3705, 3720, or 3725, that communicates between the communications facility and a host computer. IBM supports both programmable and nonprogrammable communication controllers. Hewlett-Packard's INP and PSI are types of communications controllers.

The hardware that directly connects two locations for the purpose of data transfer, including the interface boards, cables, and modems (if a telephone line is used).

A device that controls input and output for one or more devices such as printers or display stations.

See Control Unit.

In IBM terminology, any file.

A technique, using software, allowing one computer to behave exactly like another computer. An HP emulation of an IBM device is a Hewlett-Packard data communications product that enables an HP computer or terminal to carry out many of the functions of the IBM device. For example, the Hewlett-Packard SNA IMF product enables an HP computer to carry out many of the functions of an IBM 3270 device.

See Function Management Data services.

See Function Management Header.

A smaller computer that relieves a larger host computer of certain processing tasks, such as error detection, line control, and message handling.

A generic term that describes two SNA layers: Session Presentation and Session Network Services.

An SNA header that selects a destination or source for subsequent data transmission and supplies information for other data management tasks.

A central computer that provides services for other computers and terminals attached to it.

An SNA request to the SSCP to initiate an LU-LU session.

A subprogram provided by Hewlett-Packard systems. Intrinsics perform common functions such as opening files, opening communications lines, or transmitting data over a communications line.

See logical device.

Logical device number. See logical device.

The physical or logical connection between two devices in a network.

The recording of significant events that may be of use to the user at the time they occur. This is distinguished from tracing, which is the recording of events for future use.

A disc file, a set of disc files, or a physical device associated with a data stream between a host and a remote system. An HP logical device is identified either by a number or by a device class name. For SNA IMF, ldevs are identified by ldev numbers; device class names are not supported.

A set of logical units on the HP 3000. For SNA IMF, an LU class may contain multiple LUs.

A program or a set of programs within a node that provides access to an SNA network for an end user. A logical unit can support two types of sessions: (1) an LU-SSCP session and (2) an LU-LU session. The logical unit formats message units, displays information, and handles error recovery. Multiple logical units can reside in an SNA node.

A session between an application program and one or more data processing terminals. The environment may be interactive, distributed processing, or batch data transfer. Character-oriented printer devices, batch support (RJE), and the SNA Character String (SCS) are supported.

A session between an application program and one 3270-type display station using interactive data transfer. IBM 3270 Data Stream Capability (3270 DSC) and 3270-type display station support is provided.

A session between an application program and a printer. IBM 3270 Data Stream Capability (3270 DSC) is provided. Many devices support both LU.T1 and LU.T3 print requests.

See Logical Unit class.

A connection between two LUs.

See Logical Unit Type 1.

See Logical Unit Type 2.

See Logical Unit Type 3.

See Logical Unit.

An acronym for MODulator-DEModulator. A modem converts serial digital data from a transmitting terminal into a form suitable for transmission over the analog telephone channel. A second modem reconverts this signal to serial digital data for acceptance by the receiving terminal. Bell 201, 208, and 209 modems are used for synchronous data transfer.

See MultiProgramming Executive.

An IBM operating system that is an extension of OS/MVT. MVS is also known as OS/VS2 Release 2. IBM enhanced the original version of MVS; these enhanced systems include MVS/SP (Multiple Virtual Storage/System Product) and MVS/XA (Multiple Virtual Storage/eXtended Architecture).

The Hewlett-Packard operating system for the HP 3000 computer. MPE consists of programs that handle exchanges between HP terminals, printers, and executing programs and the internal HP 3000 Communications Software.

See Multiple Virtual Storage.

See Network Addressable Unit.

See Network Control Program.

Either a program or group of programs that represents the source and destination of data in a network. The three kinds of network addressable units are SSCP, LU, and PU. A communication session must exist before data can be transferred. Sessions are established by the SSCP in this order:

Four types of sessions exist:

A program that controls the operation of a communications controller.

A user-level protocol that enables the transfer or copying of files from one node to another or within a single node, interactively or programmatically.

An SNA request from the SSCP to the LU indicating an error during session startup or shutdown.

A series of points interconnected by a communications channel. These may be computers, terminals, or other peripherals.

See Network File Transfer.

See Node Management Services.

A major software component of the HP 3000 operating system that provides a common set of services to HP networking products. It includes utilities and commands for configuration, event logging, message tracing, link management, and subsystem initiation, termination and control.

A name assigned to a node configured into a Local Area Network (LAN). It must be a maximum of eight characters in length and cannot be qualified.

A set of hardware devices and associated software at the end of a data link. In an SNA network, a node can be either distributed or host processors, communications controllers, cluster controllers, or terminals.

See Network Services Procedure Error.

SNA IMF's interactive interface, which allows a terminal or printer to exchange data interactively with an IBM host.

A component of an SNA node. A PU controls the resources of a node and reports errors and physical failures to the SSCP. One PU exists per node. A PU is the access method in a host node, the NCP in the communications controller node, and the hardware and software in the peripheral nodes.

See Physical Unit.

Control information that precedes a request/response unit (RU). It specifies the type of RU and contains control information for the RU.

A message unit containing control information such as a request code, or function management headers, end-user data, or both.

Control information that indicates whether a response is positive or negative. A response unit optionally follows it.

A message unit that acknowledges a request unit. If the response unit is negative, it will contain sense data that defines the exception condition. If the response unit is positive, it may contain additional information; for example, it may contain session parameters in response to BIND SESSION.

See Request Header or Response Header.

See Request Unit or Response Unit.

See Synchronous Data Link Control.

A logical connection between two network addressable units that allows them to communicate.

See Systems Network Architecture.

See System Services Control Point.

An IBM term for a link protocol used for the transfer of data between stations. The information transfer is synchronous, thus eliminating the need for start and stop bits. It is also code-transparent, transmitted serial-by-bit, and may be transmitted in duplex or half-duplex over switched or nonswitched links. The link configuration may be point-to-point, multipoint, or loop.

A part of an SNA host node that helps to manage configurations, controls network operations, does problem solving, and provides other session services for end users. An SSCP exists only in the host and is exercised by the host's communications access method.

A comprehensive specification for distributed data processing developed by IBM. SNA defines a layered protocol for communicating and controlling a communications network within the IBM environment.

An SNA request to the SSCP to terminate an LU-LU session.

See Transmission Header.

Time limit imposed for a given task to be completed.

The recording of events for future use. See also logging.

A transmission header is used by the Transmission Control and Path Control layers of SNA for routing and sequencing data sent through an SNA network.

An IBM communications access method within the host that handles the data communications and network control details for the host.

A common IBM subsystem used to control the input and output of jobs to the VSG operating system environment.

See Virtual Telecommunications Access Method.