Glossary

A numerical identifier defined and used by a particular protocol and associated software to distinguish one node from another.

address resolution

In NS networks, the mapping of node names to IP addresses and the mapping of IP addresses to subnet addresses.

American National Standard Code for Information Interchange. A character set using 7-bit code used for information interchange among data processing and data communications systems. The American implementation of International Alphabet No. 5.

Term used to describe a device's mode of operation whereby a sequence of operations are executed irrespective of time coincidence with any event. Devices that are directly accessible by people (for example, terminal keyboards) operate in this manner.

Data transfer scheme in which no special character processing is performed. All characters are considered to be data and are passed through with no control actions being taken.

Binary digit. A unit of information that designates one of two possible states, which are represented by either 1 or 0.

Bits per second. The number of bits passing a point per second.

A logical grouping of a system's memory resources used by NS 3000/XL.

A sequence of eight consecutive bits operated on as a unit.

In X.25, a call is an attempt to set up communication between two DTEs using a virtual circuit. Also known as a virtual call.

A conflict that occurs at a DTE/DCE interface when there is a simultaneous attempt by the DTE and DCE to set up a call using the same logical channel identifier.

When a node sends out a call request packet, the packet contains the address of the destination node. The address of the destination node is the called address.

When a node receives an incoming call packet, the packet contains the address of the sending node. The address of the sending node is the calling address.

Consultative Committee for International Telephony and Telegraphy. An international organization of communication carriers, especially government telephone monopolies, responsible for developing telecommunication standards by making recommendations. The emphasis is on "recommendations"; no carrier is required to adhere to a CCITT recommendation, although most do so in their own interests.

An X.25 user facility that allows communication to and from a pre-specified group of users and no one else.

Processing mode on HP 3000 Series 900 computers that allows applications written for MPE V/E-based systems to be ported and run without changes or recompilation.

A group of computer systems connected in such a way that they can exchange information and share resources.

See closed user group.

Delivery confirmation bit. Used in the X.25 protocol, the setting of the D bit in DATA packets indicates whether delivery acknowledgment of the packet is required from the local DCE or from the remote DTE. It therefore allows the choice between local and end-to-end acknowledgment.

Transmitted data that is sent faster than the equipment on the receiving end is capable of receiving it. The resulting overflow data is lost. See also flow control.

Data circuit-terminating equipment. The interfacing equipment required in order to interface to data terminal equipment (DTE) and its transmission circuit. Synonyms: data communications equipment, dataset.

Datacommunications and Terminal Controller. The DTC is a hardware device, configured as a node on a LAN, that enables asynchronous devices to access HP 3000 Series 900 computers. Terminals can either be directly connected to the DTC, or they can be remotely connected through a Packet Assembler Disassembler (PAD). The DTC can be configured with DTC/X.25 Network Access cards and DTC/X.25 Network Access software. A DTC/X.25 XL Network Link consists of two software modules: the X.25 XL System Access software (running on the host) and the DTC/X.25 Network Access software (running on the DTC).

The software that resides on the Datacommunications and Terminal Controller (DTC). To configure access to an X.25 network, you must configure two software components, the X.25 XL System Access (residing on the HP 3000 host and configured through use of NMMGR software) and the DTC/X.25 Network Access (configured on the OpenView Windows Workstation through use of the OpenView DTC Manager software).

Software and hardware that provides MPE XL access to private and public X.25 networks. The X.25 XL System Access software resides on an HP 3000 host and is configured through use of NMMGR. The DTC/X.25 Network Access software resides on the Datacommunications and Terminal Controller and is configured at the OpenView Windows Workstation.

This is the hardware card and channel adapter that provides X.25 Network Access. It resides in the Datacommunications and Terminal Controller (DTC).

Data terminal equipment. Equipment that converts user information into data-transmission signals or reconverts received data signals into user information. Data terminal equipment operates in conjunction with data circuit-terminating equipment.

Distributed Terminal Subsystem. This consists of all the Datacommunications and Terminal Controllers (DTCs) on a LAN, their LANIC cards (attached to the host), the LAN cable, and the host and DTC software that controls all related DTS hardware.

A session that is established on a remote node.

A Local Area Network system that uses baseband transmission at 10 Mbps over coaxial cable. Ethernet is a trademark of Xerox Corporation.

One of the optional Network Subscribed Facilities that provides packet sequence numbering using modulo 128. If not subscribed, modulo 8 is used.

An optional service offered by a packet switching network's administration and requested by the user either at the time of subscription for network access or at the time a call is made. Also known as user facility.

A facility set defines the various X.25 connection parameters and X.25 facilities that can be negotiated for each virtual circuit on a per-call basis.

An optional packet-switching network facility by which user data may be transmitted as part of the control packets that establish and clear a virtual connection.

Frame Check Sequence. A sequence of bits generated by X.25 at Level 2 that forms part of the frame and guarantees the integrity of its frame's content. The FCS is also used by the IEEE802.3 protocol to check the validity of frames.

Assignment statement used to associate a file with a specific device or type of device during execution of a program.

Unique number associated with a file when the file is opened. The file number is returned in the FOPEN or HPFOPEN call used to open the file. It can be used to access that file until the file is closed.

The name and location of a file. The full specification for a file includes the file name, group, and account.

The part of the operating system that handles access to input/output devices (including those connected through the DTC), data blocking, buffering, data transfers, and deblocking.

A means of regulating the rate at which data transfer takes place between devices to protect against data overruns.

One of the network subscribed facilities, selected at subscription time; this facility allows the Flow Control parameter to be negotiated at call set-up time, as opposed to having a predefined value.

Name that can be used programmatically or in a file equation to refer to a file.

Fundamental Operating System. The programs, utilities, and subsystems supplied on the Master Installation Tape that form the basic core of the MPE XL operating system.

A method of configuring a node wherein a subset of the complete NMMGR interface is presented and defaults of configurable values are used automatically.

The primary or controlling computer on a network. The computer on which the network control software resides. For HP purposes, it may also be used to distinguish the MPE XL system (host) from the DTC.

Method of managing asynchronous communications for HP 3000 Series 900 computers. All of the control software is configured on a single MPE XL host and is downloaded to the DTCs that are managed by that host. With host-based management, there is a permanent relationship between each DTC and the host, and terminal users can access only the single MPE XL system that owns the DTC their terminal is connected to.

Timeout defined by the Configure:CPU command. ; When the timer lapses, a device connected to the DTC user interface that is still inactive will be disconnected.

A standard for a broadcast local area network published by the Institute for Electrical and Electronics Engineers (IEEE). This standard is used for both the ThinLAN and ThickLAN implementations of the LAN.

Intelligent Network Processor. The card residing in the back of an MPE V-based node that provides a point-to-point or X.25 interface.

Communication that occurs between networks.

A protocol used to provide routing between different local networks in an internetwork, as well as among nodes in the same local network. The Internet Protocol corresponds to Layer 3, the Network Layer, of the OSI model. See also IP address.

Two or more networks joined by gateways.

Communication that occurs between nodes in a single network.

System routine accessible by user programs which provides an interface to operating system resources and functions. Intrinsics perform common tasks such as file access and device control.

See Internet Protocol.

Internet Protocol address. An address used by the Internet Protocol to perform internet routing. A complete IP address comprises a network portion and a node portion. The network portion of the IP address identifies a network, and the node portion identifies a node within the network.

International Organization of Standards. An international federation of national standards organizations involved in developing international standards, including communication standards.

See Local Area Network Interface Controller.

A ROM-based program on a LANIC card that tests and reports the status of the LANIC hardware.

Link Access Protocol - Balanced. The data link protocol specified by the 1980 version of X.25 at Level 2 that determines the frame exchange procedures. LAP-B must also be used over direct-connect NS Point-to-Point 3000/XL Links.

See logical device number.

The name that represents a hardware interface card. The link name can contain as many as eight characters. All characters except the first can be alphanumeric; the first character must be alphabetic.

A hardware card that fits into the backplane of the HP 3000 Series 900 computer and provides a physical layer interface for IEEE 802.3 local area networks.

See direct connection.

The computer that you are configuring or that you are logged on to.

The process of recording the usage of network resources. Events can be logged to both the OpenView workstation and to the MPE XL host.

A number defining the severity of any given event logged. An operator uses the logging classes to specify which events are to be logged. Class 1 (catastrophic event) is always logged.

A value by which MPE XL recognizes a specific device.

The routing of messages from a node back to itself.

Local User Group. A list defined for a particular DTC and card that specifies which remote nodes this DTC can send data to and also which remote nodes this DTC can receive data from. (See also Closed User Group).

More data bit. Setting this bit in a DATA packet indicates that at least one more DATA packet is required to complete a message of contiguous data.

Value used as the counting cycle for determining the send sequence number (N(S)) of frames sent across an X.25 network.

MultiProgramming Executive XL. The operating system of the HP 3000 Series 900 computers. The NS3000/XL network services operate in conjunction with the MPE XL operating system.

MUX. A device that allows multiple communication links to use a single channel.

The run-time environment of MPE XL. In Native Mode, source code has been compiled into the native instruction set of the HP 3000 Series 900 computer.

Network Interprocess Communication. Software that enables programs to access network transport protocols.

A group of computers connected so that they can exchange information and share resources.

This can be either 1) the network portion of an IP address as opposed to the node portion, or 2) when referring to X.25 networks, it is a node's X.25 address.

The logical division between networks in an internetwork.

A file containing information required for one node to communicate with other nodes in 1) an internetwork, 2) an X.25 network, or 3) a network that contains non-HP nodes. The active network directory on a node must be named NSDIR.NET.SYS.

The collective software that enables data communication between a system and a network. A node possesses one or more network interfaces for each of the networks to which it belongs. Network interface types are LAN802.3, router (point-to-point), X.25, loopback, and gateway half. The maximum number of supported NIs is 12, one of which is reserved for loopback.

The collective tasks required to design, install, configure, maintain, and if necessary, change a network.

NS. Software application products that can be used to access data, initiate processes, and exchange information among nodes in the network. The HP 3000/XL Network Services include RPM, VT, RFA, RDBA, and NFT.

A set of parameters that the user chooses when he subscribes to the X.25 network; they include Flow Control Negotiation, Use of D-bit, Throughput Class Negotiation and Extended Packet Sequence Numbering.

Network File Transfer. The network service that transfers disc files between nodes on a network.

See network interface.

A file that contains all the network configuration data for the HP 3000 Series 900 computer on which it resides. It includes information about the DTCs that can access the system as well as information about any Network Service (NS) products running on the system. This is the only file name allowed.

A utility used to format log and trace files.

A utility that lists the software module version numbers for all HP AdvanceNet products, including NS 3000/XL. It detects missing or invalid software modules.

ode Management Services Configuration Manager. A software subsystem that enables you to configure DTC connectivity and network access parameters for an HP 3000 Series 900 computer.

A conversion program called NMMGRVER.PUB.SYS. It converts configuration files created with NMMGR from an earlier version to the latest format.

Sample configuration file supplied with FOS that can be used as a template for DTS configuration.

A computer that is part of a network. The DTC is also considered to be a node and has its own address.

The node portion of an IP address, which consists of a node portion and a network portion.

See NMMGR.

A character string that uniquely identifies each system in a network or internetwork. Each node name in a network or internetwork must be unique; however, a single node can be identified by more than one node name.

A Hewlett-Packard data communication product that provides networking capabilities for MPE XL based HP 3000 minicomputers. NS 3000/XL consists of a link and network services.

Software and hardware that provides the connection between nodes on a network. Some of the NS 3000/XL links available are the ThinLAN 3000/XL Link and its ThickLAN option, the DTC/X.25 XL Network Link, the NS Point-to-Point 3000/XL Link, and the StarLAN 10 3000/XL link.

Software applications that can be used to access data, initiate processes, and exchange information among nodes in a network. The services are RPM, VT, RFA, RDBA, and NFT.

Name of the active network directory file. See also network directory.

An eight-bit byte operated upon as an entity.

Open Systems Interconnection model. A model of network architecture devised by the International Standards Organization (ISO). The OSI model defines seven layers of a network architecture, with each layer performing specified functions.

A block of data whose maximum length is fixed. The unit of information exchanged by X.25 at Level 3. There are DATA packets and various control packets. A packet type is identified by the encoding of its header.

PXP. A transport layer protocol used in NS3000/XL links to initially establish communication between nodes when NetIPC socket registry is used.

The name of a data communication network adhering to the CCITT X.25 recommendation. This can be a PDN or a private network, such as the HP PPN.

A device that converts asynchronous character streams into packets that can be transmitted over a packet switching network (PSN).

A name of up to eight characters that is associated with a configured PAD device. The PAD name is known to both the DTC (defined by the DTC Manager) and the MPE XL systems (defined by NMMGR) that the device can access.

Terminal or printer profile that specifies the configuration characteristics for PAD-connected devices.

Public data network. A data communication network whose services are available to any user willing to pay for them. Most PDNs use packet switching techniques.

An outlet through which a device can be connected to a computer, consisting of a physical connection point and controlling hardware, controlling software, and configurable port characteristics. Ports can be thought of as data paths through which a device communicates with the computer.

The hardware design structure for the HP 3000 Series 900 computer family.

A capability assigned to accounts, groups, or users allowing unrestricted memory access, access to privileged CPU instructions, and the ability to call privileged procedures.

An HP protocol used by NS 3000/XL IEEE 802.3 networks to obtain information about other nodes on the network.

A node on an IEEE 802.3 network that possesses a network directory. A probe proxy server can provide a node with information about other nodes on the same or other networks of an internetwork.

A method of grouping device connection specifications and characteristics so that the set of characteristics can be easily associated with groups of like devices. See also printer profile, terminal profile.

A device operating under control of a program running on a computer. Programmatic devices can be used for input, output, or both, depending on the device and how it is opened by the controlling program.

A set of rules that enables two or more data processing entities to exchange information. In networks, protocols are the rules and conventions that govern each layer of network architecture. They define what functions are to be performed and how messages are to be exchanged.

Packet-Switching Network. Any data communication network using packet-switching techniques wherein data is disassembled into packets at a source interface and reassembled into a data stream at a destination interface. A public PSN offers the service to any paying customer.

Permanent Virtual Circuit. A permanent logical association between two physically separate DTEs that does not require call set-up or clearing procedures.

See Packet Exchange Protocol.

Qualified bit. When set in DATA packets the Q bit signifies that the packet's user data is a control signal for the remote device, not a message for its user.

A software program that tests whether Network Services are operating correctly between nodes.

Remote Data Base Access. A network service that allows users to access data bases on remote nodes.

A node on an internetwork other than the node you are currently using or referring to.

The maximum number of times a frame will be retransmitted following the expiration of the Retransmission Timer, T1.

Length of time the transmitter will wait for an acknowledgment from the destination address before attempting to retransmit the frame. When choosing this value, factors like the line speed and maximum frame size should be taken into account.

Remote File Access. A network service that allows users to access file and devices on remote nodes.

Routing refers to the process used to determine the path that packets, or fragments of a message, take through a network to reach a destination node.

Remote Process Management. A network service that allows a process to programmatically initiate and terminate other processes throughout a network from any node on the network.

An alphanumeric character string that functions as a password for dial links. The security string is used by the Dial IP protocol.

Switched Virtual Circuit. Path through an X.25 network that is established at call set-up time.

A mode of operation or transmission whereby a continuous data stream is generated without intervals between characters. The data stream is synchronized by clock signals at the receiver and transmitter. As a result, fast transmission speeds (above 9600 bps) are attainable.

The way you tell MPE XL what peripheral I/O devices are attached to the DTC and what parameters are required for system operation.

See Transmission Control Protocol

A LAN that conforms to the IEEE 802.3 Type 10 BASE 2 standard LAN.

A value assigned to a given virtual circuit that defines how many network resources should be assigned to a given call. It is determined by the access line speed, packet and window sizes, and the local network's internal mechanisms.

One of the Network Subscribed Facilities defined at subscription time. This allows the user to negotiate the Throughput Class at call set-up time.

Length of time that a link can remain in an idle state. After the expiration of the timer, the link is considered to be in a non-active, non-operational state and is automatically reset. The value should be chosen carefully. In particular, it must be sufficiently greater than the Retransmission Timer (T1) so that there is no doubt about the link's state.

The physical arrangement of nodes in a network. Some common topologies are bus, star, and ring.

TCP. A network protocol that establishes and maintains connections between nodes. TCP regulates the flow of data, breaks messages into smaller fragments if necessary (and reassembles the fragments at the destination), detects errors, and retransmits messages if errors have been detected.

Data transfer scheme in which only a limited number of special characters retain their meaning and are acted on by the system. All other characters are considered to be data and are passed through with no control actions being taken.

Software that corresponds to layers 4 and 3 of the OSI network architecture model. The function of this software is to send data out over the appropriate communications link, to receive incoming data, and to route incoming or outgoing data to the appropriate destination node.

The number of frames that can be transmitted without receiving an acknowledgment from the destination address. When this number (K) frame is reached, the same K frames are retransmitted.

See transparent mode.

A set of CCITT recommendations related to data communication over a voice-grade telephone network.

The CCITT recommendation that defines the function of the interchange circuits between a DTE and a DCE.

The process of ascertaining whether the network transport configuration file has been correctly configured. This is accomplished by using the NMMGR Validate Configuration File screen.

Value-Added Network. A data communication network that uses and pays for facilities belonging to another carrier. The value-added package is then sold to a user.

See virtual circuit.

A logical association between two physically separate DTEs.

A network service that allows a user to establish interactive sessions on a node.

Software used to generate screens such as those displayed by NMMGR.

See Virtual Terminal.

A utility available on MPE XL systems that allows users to create customized terminal and printer types by entering data through a series of VPLUS screens.

Defines the physical interface between a DTE and a DCE of a public data network where the access to the network is made over synchronous digital lines.

Defines the interface between a DTE and a DCE for packet mode operation on a Public Data Network (PDN).

The X.25 address provided by the network administration if you are connected to a Public Data Network (PDN).

An X.25 address key is a label that maps a node's IP address to its X.25 address and its associated X.25 parameters. You have a combined maximum of 1024 X.25 address keys in the SVC and PVC path tables.

X.25 address of a node belonging to a LUG.

he software that works in conjunction with the DTC/X.25 Network Access software to provide MPE XL access to X.25. The software resides on an HP 3000 host and is configured through use of NMMGR. To configure access to an X.25 network, you must configure two software components, the X.25 XL System Access and the DTC/X.25 Network Access (residing on the Datacommunications and Terminal Controller and configured at the OpenView Windows Workstation). Together, these two components provide a network connection on HP 3000 systems to private and public X.25 packet-switched networks PSNs).

Defines the interface for data exchange between a packet-mode DTE and a remote Packet Assembly/Disassembly (PAD) facility over a packet switching network.

Defines the user facilities that should be internationally available from the packet assembler/disassembler (PAD) facility when this is offered by a public data network.

A set of recommendations for data communication networks governing their services, facilities, and the operation of terminal equipment and interfaces.