HP 3000 Manuals HP 3000 Manuals
Appendix D Glossary Glossary (a - m) access port A special interface card in the system cabinet through which the MPE/iX system console is connected. ADCP Avesta Device Control Protocol. An HP proprietary protocol which provides device control features. ADCP is optimized for communications between a DTC and MPE/iX systems address A numerical identifier defined and used by a particular protocol and associated software to distinguish one node from another. address key See X.25 address key. address resolution In NS networks, the mapping of node names to IP addresses and the mapping of IP addresses to subnet addresses. address resolution protocol (ARP) A protocol used to convert an IP address to a low level hardware address. ARP can be used only over a single physical network and is limited to networks that support hardware broadcast. adjacent A node on a point-to-point network that is connected to another node by a single link with no intervening nodes. ADP Active Distribution Panel. See MDP. AFCP Avesta Flow Control Protocol. An HP proprietary protocol which provides data flow control features. AFCP is optimized for communications between nodes, including DTCs, in an MPE/iX environment. ARP See address resolution protocol. ARPA Advanced Research Projects Agency. It is the former name of the Defense Advanced Research Project Agency (DARPA). The Internet suite of protocols was developed under ARPA guidance. ARPA Telnet Access An HP product which is a board that can be installed in a DTC 48 and DTC 72MX. The Telnet Access board performs protocol translation. Calls to the IP address of an MPE/iX system are detected by the Telnet Access board and are retransmitted on the LAN using AFCP, allowing connections from terminals on ARPA systems to HP 3000s. ARPA Telnet Express An HP product which is a standalone hardware platform dedicated to performing protocol translation. Calls to the IP address of an MPE/iX system are detected by the Telnet Express and are retransmitted on the LAN using AFCP, allowing connections from terminals on ARPA systems to HP 3000s. ASCII 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. asynchronous A device's mode of operation in which 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. asynchronous processor board The new 24-port mux board for the DTC 72MX. Allows up to 24 direct and modem connections per board. A DTC 72MX can have up to 3 asynchronous processor boards (for a total of 72 connections). Attachment Unit Interface AUI. The cable that runs between each node (host, DTC, or other device) and the Medium Attachment Unit (MAU) that connects it to the LAN in a ThickLAN configuration. autodial A dial link in which the remote node's telephone number is automatically dialed by a modem or other device with this capability. automatic configuration The addition and configuration of a host-based managed DTC to the HP 3000 system without needing to specify detailed configuration information such as DTC cards/boards and ldevs. backbone LAN A thick LAN cable conforming to the IEEE 802.3 Type 10 BASE 5 Standard. back-to-back configuration A DTC configuration whereby MPE users connected to one DTC can communicate with a non-MPE/iX system connected to another DTC via the LAN. See also Local Switching. backup configuration file A file that contains a copy of the information contained in the configuration file. The backup file, called NMCBACK.group.account by default, is updated each time the configuration file is successfully validated. banner A welcome message displayed on your screen. On the local OpenView workstation a banner appears when a remote connection is established with the OpenView DTC Manager. A banner also can appear when you log on to MPE. baud The measure of the speed at which information travels between devices, most commonly used in reference to terminal speed settings. Baud represents signal events per second. When one bit represents each signal change, baud is the same as "bits per second." binary mode A 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. bit Binary digit. A unit of information that designates one of two possible states, which are represented by either 1 or 0. block mode A terminal processing mode in which groups, or "blocks," of data are transmitted all at once. BNC T-Connector A connector used to connect a computer or a component such as a DTC to the LAN in a ThinLAN configuration. boundary See network boundary. bps Bits per second. The number of bits passing a point per second. bridge A device that is used to connect LAN segments. broadcast Communication method of sending a message to all devices on a link simultaneously. buffer A logical grouping of a system's memory resources used by NS3000/iX. byte A sequence of eight consecutive bits operated on as a unit. call 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. call collision 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. called address 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. calling 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. carrier A continuous wave that is modulated by an information-bearing signal. catenet See internetwork. CCITT 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. CIB The channel input/output bus in the backplane of an HP 3000. circuit-switching network A type of data communications network wherein a physical and exclusive link is maintained between two communicating devices for the call duration. An all-digital, circuit- switching network is often referred to as an X.21 network. closed user group An X.25 user facility that allows communication to and from a pre-specified group of users and no one else. compatibility mode A 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. computer network A group of computer systems connected in such a way that they can exchange information and share resources. configuration 1) The way in which computer equipment is physically interconnected and set up to operate as a system. 2) The layout of the computer system, including the MPE table, memory, and buffer sizes, that tells which peripheral devices are (or can be) connected to the computer and how they can be accessed. 3) The process of defining the characteristics of a network in software. For MPE/iX-based computers, the operating systems are configured through use of the SYSGEN utility. Next, the Datacommunications and Terminal Subsystem (DTS) link is configured by using NMMGR (running on the host) and can, in addition, be configured using the OpenView DTC Manager software (running on the OpenView Windows Workstation) depending on the type of network management you use. A system that is to run network services (NS3000/iX) is configured through use of NMMGR. Access to X.25 is configured in two parts. The X.25 MPE/iX System Access software is configured on the host through use of NMMGR. The DTC/X.25 Network Access software residing on the DTC is configured at the OpenView Windows Workstation through use of the OpenView DTC Manager. configuration file The configuration file contains the information that the network needs in order to operate. This file also contains information necessary for link- level and NetIPC logging. The only file name that the system recognizes is NMCONFIG.PUB.SYS control-X echo Three exclamation marks (!!!) output to the terminal screen when the cancel character (normally [CTRL]-X) is entered. control-Y trap A user-written procedure to which control is passed when the subsystem break character (normally [CTRL]-Y) is entered during execution of a program with subsystem break enabled. cross-validate The process of assuring that information contained in two locations is consistent where it is imperative that it be consistent. For example, an automatic cross-validation occurs when you enter SYSGEN to assure that information contained in NMCONFIG.PUB.SYS agrees with system configuration data. CSMA/CD Carrier Sense Multiple Access with Collision Detect, transmission access method used by the IEEE 802.3 LAN standard. CSN See circuit-switching network. CTB The cache transfer bus in the backplane of an HP 3000. CUG See closed user group. data Basic elements of information that can be processed or produced by a computer. Datacommunications and Terminal Controller See DTC. datagram A self-contained packet that is independent of other packets. It does not require an acknowledgment and it carries information which is sufficient to route it from one DTE to another DTE without relying on earlier exchange between the DTEs. data overrun Transmitted data that is sent faster than the receiving equipment can receive it. The resultant overflow data is lost. See also flow control. Datapac The national public PSN of Canada. Datex-P The national public PSN of West Germany. D bit 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. DCE 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. A modem is an example of a DCE. DDFA DTC Device File Access Utilities. A set of HP-UX utilities which is used by systems and user written applications to programmatically access devices attached to DTC ports. DDP Direct Distribution Panel; a distribution panel that serves as the electrical and physical interface between a DTC 72MX mux board (asynchronous processor board) and up to eight asynchronous devices for direct connections. See MDP for modem connections. DDX The national public PSN of Japan. dedicated printer A printer that can be used only by one host on the LAN--the one specified in the Destination Node Name in that printer's configuration screen. demodulation The process by which the information-bearing signal is retrieved from a modulated carrier wave. The inverse of modulation. destination node name In DTS configuration, it is either 1) the name of a host that a user can be connected to by default (if switching is not enabled for that user, or if automatic modem connection is enabled), or 2) the name of the only host that can access a dedicated printer. device class A collection of devices that have some user-defined relation. Device classes are assigned through use of the NMMGR configuration program. device-dependent characteristic A file specification for which modifications are restricted because of the type of device on which the file is opened. For example, data directed to terminals must have a blocking factor of one. device driver A software module that controls a specific type of input/output device. devicefile A file being input to or output from any peripheral device except a disk. MPE/iX allows operations to be performed on the device itself as if it were a file. device independence A characteristic of the operating system that allows users to selectively redirect input/output from a program, session, or job without regard to the nature of the device. device name See PAD name. Dial ID protocol A proprietary Hewlett- Packard protocol that provides security checking and address exchange for dial links. dial link A connection made through public telephone lines. direct-connect device An asynchronous device that is connected directly to a DTC through an RS-232-C or RS-422 cable, with no intervening communications equipment. Also referred to as a "local connection." direct connection A leased line, private line, or other non-switched link in a network. direct dial A dial link through which only one remote node can be reached. direct-path branching The process of directly accessing any screen in NMMGR by entering a path name in the Command: field. The path name must be preceded by an at sign (@). download The process of loading operating code and configuration files into the DTC's memory. The DTC is downloaded by the MPE/iX host for LANs using host-based network management, and by the PC for DTCs managed by the OpenView DTC Manager. driver Software that controls input/output devices including NS3000/iX links. DTC 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 iX Network Link consists of two software modules: the X.25 iX System Access software (running on the host) and the DTC/X.25 Network Access software (running on the DTC). DTCCNTRL A command file you can use to manage DTS configurations. Using DTCCNTRL, you can dynamically implement DTS changes, automatically add a new DTC, shutdown/restart DTS, and manage/dynamically configure host-based X.25 connections. DTC 16 HP 2340A product. A DTC that provides 2 slots for asynchronous connections with each slot allowing up to 8 direct connections or 6 modem connections, plus an optional X.25 link supporting up to 32 virtual circuits at speeds of up to 19.2 Kbps. DTC 16iX HP J2062A product. A DTC terminal server for HP 3000 systems. It allows up to 16 asynchronous (direct and modem) LAN connections to HP 3000 systems. DTC 16MX HP J2063A product. A DTC terminal server for HP 3000 and Telnet systems. It allows up to 16 asynchronous (direct and modem) LAN connections for the HP 3000 environment and for computer systems running ARPA, such as HP 9000s and third party systems. When managed by the HP 3000, the DTC 16MX is configured and functions exactly like a DTC 16iX. The full functionality of the DTC 16MX is only available when it is managed by the OpenView DTC Manager. DTC 16RX HP J2064A product. A routable communications server that enables up to 16 asynchronous connections for the HP 3000 environment and computer systems running ARPA, such as HP 9000s and third party systems. DTC 16RX Manager An application program that resides on the HP 9000 host system and enables you to configure and diagnose the HP DTC 16RX Routable Communications Server. DTC 16TN HP J2060A product. A DTC terminal server for Telnet systems. It allows up to 16 asynchronous connections to computer systems running ARPA, such as HP 9000s and third party systems. DTC 48 HP 2345B product. A DTC that provides 6 slots for asynchronous connections, X.25 links, or Telnet Access. Each slot allows up to 8 direct connections or 6 modem connections. A DTC 48 may have up to 3 slots used for X.25 links, each supporting up to 256 virtual circuits at speeds of up to 64 Kbps or one Telnet Access card with 40 Telnet connections to HP 3000 Series 900 connections. DTC 72MX HP J2070A product. A DTC that provides 3 slots allowing up to 72 asynchronous connections. Each slot accommodates up to 24 direct or modem connections. A DTC 72MX may have up to 3 slots used for X.25 links, each supporting up to 256 virtual circuits at speeds of up to 64 Kbps. It may also use one slot for Telnet Access card with 40 Telnet connections to HP 3000 Series 900 computers. DTC identifier An identifier used only within NMMGR to define the branch of the configuration file containing information about a particular DTC. The identifier must begin with a letter and can be up to eight characters long. DTC Manager See OpenView DTC Manager. DTC node name A unique name used to identify a DTC on a LAN. The node name format is nodename.domain.organization, with each of the three parts having up to 16 characters. The name begins with either a letter or a digit. DTC station address (802.3 address) A 12-digit hexadecimal number used to identify the DTC as a node belonging to the network configuration. Also called the LAN address or node address. DTC switching A facility enabling terminal users to select any host system that they want to connect to. DTC switching is available only when the OpenView DTC Manager is used for network management. DTC/X.25 Network Access 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 iX System Access (residing on the HP 000 host and configured through use of NMMGR software), and DTC/X.25 Network Access (configured on the OpenView Windows Workstation through use of the OpenView DTC Manager software for PC-based management, and through NMMGR for host-based management). DTC/X.25 Network Access card The hardware card and channel adapter that provides X.25 Network Access. It resides in the Datacommunications and Terminal Controller (DTC). DTC/X.25 iX Network Link Software and hardware that provides MPE/iX access to private and public X.25 networks. The X.25 iX 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 for PC-based management and through NMMGR for host-based management. DTE 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. DTS Datacommunications and Terminal Subsystem. This consists of all of 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. DTS restart The startup of the DTS subsystem using the DTCCNTRL command file after DTS has been shut down. DTS shutdown The shutdown of the DTS subsystem, including the release of all TIO-related resources, using the DTCCNTRL command file. duplex A transmission method that allows two-way communication. If both ends of the transmission link can transmit simultaneously, it is called full duplex. If only one end can transmit at a time, it is half-duplex transmission. dynamic configuration The ability to make DTS configuration changes using NMMGR without rebooting the HP 3000 system. entry priority In a point-to-point network, it is a ranking that identifies the most desirable route for data to travel from a given local node to a remote node. environment A session that is established on a remote node. escape from data transfer character A character that allows a user who is connected to a host system through the DTC, to break that connection and return to the DTC switching user interface. The default is [CTRL]-K. This character is used only on networks managed by the OpenView Windows Workstation. escape sequence A sequence of characters beginning with the escape character and followed by one or more other characters, used to convey control directives to printers, plotters, or terminals. Ethernet A Local Area Network system that uses baseband transmission at 10 Mbps over coaxial cable and unshielded twisted pair. Ethernet is a trademark of Xerox Corporation. event log One of three circular files stored on the OpenView windows workstation. It contains lists of events that are reported by the DTCs for which it is responsible. extended packet sequence numbering One of the optional Network Subscribed Facilities that provides packet sequence numbering using modulo 128. If not subscribed, modulo 8 is used. facility 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. facility set 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. fast select An optional packet-switching network facility by which user data can be transmitted as part of the control packets that establish and clear a virtual connection. FCS 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 contents. The FCS is also used by the IEEE 802.3 protocol to check the validity of frames. file equation An assignment statement used to associate a file with a specific device or type of device during execution of a program. file number A 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. file specification The name and location of a file. The full specification for a file includes the file name, group, and account. file system 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. flow control A means of regulating the rate at which data transfer takes place between devices to protect against data overruns. flow control negotiation 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. formal file designator A name that can be used programmatically or in a file equation to refer to a file. FOS Fundamental Operating System. The programs, utilities, and subsystems supplied on the Master Installation Tape that form the basic core of the MPE/iX operating system. full gateway A full gateway is a node that belongs to more than one network and has one IP address for each network. It uses store and forward to transfer packets between each network that it belongs to. gateway A node that connects two dissimilar network architectures. A gateway can be either a single node (full gateway) or two gateway halves. gateway half A node that works in conjunction with another node on another network to form an internetwork. The only protocol used by gateway halves is the NS Point-to-Point 3000/iX Link. See also full gateway. gateway-half link A link between the two nodes of a gateway-half pair. Each of the two nodes of a gateway-half pair has a configured link (hardware interface card) that is used for the gateway half network interface. The NS Point-to-Point 3000/iX Link is the only link that can be used as a gateway-half link. gateway-half pair A set of two nodes that are joined by a gateway-half link. Each node in the pair must have a gateway-half network interface configured, using the link. guided configuration A method of configuring a node in which a subset of the complete NMMGR interface is presented, and defaults of configurable values are used automatically. handshaking A communications protocol between devices or between a device and the CPU. Provides a method of determining that each end of a communications link is ready to transmit or receive data, and that transmission has occurred without error. hardware handshake Uses modem signals CTS and RTS to pace the data transfer from the DTC to the attached device. (For DTC 72MX only.) hop count See internet hop count and intranet hop count host-based network management A method of managing asynchronous communications for HP 3000 Series 900 computers. All of the control software is configured on a single MPE/iX host and is downloaded to the DTCs that are managed by that host. With host-based management, a permanent relationship exists between each DTC and the host. Terminal users can access only the single MPE/iX system that owns the DTC their terminal is connected to. host computer The primary or controlling computer on a network. The computer on which the network control software resides. For HP purposes, it can also be used to distinguish the MPE/iX system (host) from the DTC. HP ARPA Telnet Express A DTC dedicated to providing protocol conversion between Telnet on TCP/IP and AFCP to allow incoming calls from the ARPA environment to HP 3000 systems. HP block mode A block mode transmission method employed by HP computers where the system controls the block mode handshake. When HP block mode is used, the user program need not concern itself with data transfer protocol. HP PPN Hewlett-Packard Private Packet Network. Hewlett-Packard's own packet- switching X.25 network, which gives users full control over the administration and security of their data communication. HP TS8 A terminal server that can support up to eight asynchronous serial connections. When used in back-to-back configuration, users can access HP 3000 MPE/V systems on it through a DTC. idle device timeout A 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. IEEE 802.3 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. IEEE 802.3 multicast address A hexadecimal number that identifies a set of nodes. This address is used for multicast delivery. IEEE 802.3 nodal address A unique hexadecimal number that identifies a node on an IEEE 802.3 LAN. initialization string A sequence of control characters used to initialize a terminal, printer, or plotter when a connection is established from a host on the network. INP 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. interactive communications Processing that allows users to enter commands and data at the terminal and receive an immediate response. Interactive processing occurs in session mode on MPE/iX systems. internet communication Communication that occurs between networks. internet hop count The number of full gateways plus the number of gateway-half links that a packet must pass through in moving from source node to destination. Internet Protocol 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. internet routing Internet routing involves all the processes required to route a packet from a node on one network to a destination node on another network. internetwork Two or more networks joined by gateways. intranet communication Communication that occurs between nodes in a single network. intranet hop count The number of intermediate nodes that lie between a source and destination node on the same point-to- point network. intranet routing Intranet routing involves all the processes required to route a packet from one node in a network to another node in the same network. intrinsic A system routine accessible by user programs. It provides an interface to operating system resources and functions. Intrinsics perform common tasks such as file access and device control. IP See Internet Protocol. IP address Internet Protocol address. An address used by the Internet Protocol to perform internet routing. A complete IP address consists of 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. IP router A node in an IP network that connects two or more networks and provides address mapping between them. The router selects messages from incoming buffers and places them into the appropriate outgoing message queues. ISO International Organization of Standards. An international federation of national standards organizations involved in developing international standards, including communication standards. LAN Local Area Network. A collection of data communication systems sharing a common cable whereby each system can communicate directly with another LAN address See DTC station address. LANIC See Local Area Network Interface Controller LANIC physical path The physical location (slot number) of the LANIC within the SPU. LANIC Self-Test A ROM-based program on a LANIC card that tests and reports the status of the LANIC hardware. LAP Link Access Protocol. The data link protocol specified by older versions (prior to 1980) of X.25 at Level 2 but still permitted and therefore usable. All new implementations of X.25 must use LAP-B, and all old implementations must migrate to LAP-B at a future date. LAP-B 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/iX Links. LCI Logical Channel Identifier. Local value on a network node which identifies the channel used to establish a virtual circuit (SVC or PVC) through an X.25 network. ldev See logical device number. leased line A data-grade telephone line leased directly to a subscriber and allocated specifically for the subscriber's needs. line speed The speed at which data is transferred over a specific physical link (usually measured in bits or kilobits per second). link name A 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. Local Area Network Interface Controller (LANIC) 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. local connection See direct connection. local node The computer that you are configuring or that you are logged on to. local switching A feature of the DTC which permits back-to-back configuration (for connections to an HP 3000 MPE/V host), using two ports of the same DTC. logging The process of recording the usage of network resources. Events can be logged to both the OpenView workstation and to the MPE/iX host. logging class 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. logical device number (ldev) A value by which MPE/iX recognizes a specific device. All DTC devices that are configured as nailed devices through the NMMGR configuration have ldev numbers permanently assigned. The DTC devices can then be accessed programmatically through use of their ldev number. Non-nailed devices have ldev numbers that are assigned from a pool of available ldev numbers for the life of their connection to a system. Each nailed port configured in NMMGR must have a unique ldev number. log off The termination of a job or session. log on The process of initiating a job or session. logon device See session-accepting device. loopback The routing of messages from a node back to itself. LUG 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. maintenance mode An NMMGR character mode interface used to manage both network directory and configuration files. It can be used interactively, from within the screen mode interface, or as a set of commands entered via a batch job. map, network A drawing that shows the topology of the network. For networks managed by the OpenView DTC Manager a network map must be created through use of the OVDraw capability provided with the management software. A network map is also a hardcopy drawing used when planning a network. It shows network topology, node and network names, addresses, network boundaries (for an internetwork map), and link types. mapping A set of characteristics that describe a route taken by messages to reach a destination node. This set of characteristics is configured with NMMGR at every node on a point-to-point network. One mapping is configured at each node for every other node on the network to which messages will be sent. MAU Medium Attachment Unit. A device attached to a ThickLAN coaxial cable that provides the physical and electrical connection from the AUI cable to the coaxial cable. M bit 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. MDP Modem Distribution Panel. A distribution panel that serves as the electrical and physical interface between a DTC 72MX mux board (asynchronous processor board) and up to eight asynchronous devices for direct or modem connections. Also called ADP. MIB Management Information Base. A database of information about a network node used by SNMP. MIT Master Installation Tape. A magnetic tape containing the Fundamental Operating System for an HP 3000 Series 900 computer. modem modulator/demodulator. A device that modulates and demodulates signals. Primarily used for modulating digital signals onto carriers for transmission and for performing the inverse function at the receiving end. Modems are essential for transmitting and receiving digital signals over telephone lines. modulo Value used as the counting cycle for determining the send sequence number (N(S)) of frames sent across an X.25 network. modulation The process in which certain characteristics of a carrier signal are altered in accordance with the changes of an information-bearing signal. MPE/iX MultiProgramming Executive iX The operating system of the HP 3000 Series 900 computers. The NS3000/iX network services operate in conjunction with the MPE/iX operating system. multiplexer MUX. A device that allows multiple communication links to use a single channel.