Glossary- M
A Data Communication Historical Series
By Bob Pollard

HOME                     INDEX

MAC:

Media Access Control: An access control protocol defined by IEEE 802, which includes variations for the token ring, token bus and Carrier Sense Multiple Access/Carrier Detect (CSMA/CD).

MAC ADDRESS:

Media Access Control Address: Standardized data link layer address that is required for every port or device that connects to a LAN. Other devices in the network use these addresses to locate specific ports in the network and to create and update routing tables and data structures. MAC addresses are 6 bytes long and are controlled by the IEEE. Also known as a hardware address, MAC layer address, and physical address. Compare with network address.

MAC ADDRESS LEARNING:

Media Access Control Address Learning: Service that characterizes a learning bridge, in which the source MAC address of each received packet is stored so that future packets destined for that address can be forwarded only to the bridge interface on which that address is located. Packets destined for unrecognized addresses are forwarded out every bridge interface. This scheme helps minimize traffic on the attached LAN(s). MAC address learning is defined in the IEEE 802.1 standard.

MAC LAYER ADDRESS:

See MAC Address

MACIP:

Network layer protocol that encapsulates IP packets into DDP packets for transmission over AppleTalk; Mac-IP provides proxy ARP services.

MACHINE LANGUAGE (CODE):

The only language (internally) a computer understands. All programs are either written in or converted to machine language prior to operation in the computer. A digital code represented by 1's and 0's.

MACRO:

A macro is a series of instructions designed to simplify repetitive tasks within a program such as Microsoft Word, Excel or Access. Macros execute when a user opens the associated file. Microsoft's latest macro programming language is simple to use, powerful, and not limited to Word documents. Macros are in mini-programs and can be infected by viruses.

MACRO INSTRUCTION:

A symbolic program language statement that produces several machine (computer) instructions

MACRO VIRUS:

A macro virus is a malicious macro. Macro viruses are written in a macro programming language and will attach to a document file (such as Word or Excel). When a document or template containing the macro virus is opened in the target application, the virus runs, does its damage and copies itself into other documents. Continual use of the program results in the spread of the virus.

MADI:

Multi-channel Audio Digital Interface: MADI is an interface standard described by the Audio Engineering Society (AES) standards AES-10 and AES-10id. It was developed by Neve, Sony, and SSL as an easy way to interface digital multi-track tape recorders to mixing consoles.

MADS:

Message Accountability and Delivery System: DLA data processing System residing on host mainframe (s).

MAE:

Metropolitan Access Exchange: One of a number of Internet exchange points. Examples include MAE West and MAE East

MAGNETIC CORE:

An original (past) memory medium consisting of a magnetic substance capable of assuming and remaining in one of two states; the memory components are shaped in a circle similar to a donut, only very small. Selection is through X, Y coordinates, which required two current flows for each core selection. A third circuit senses the status of the core unit, 1 or 0. Each memory module normally contains 4096-bit representation.

MAGNETIC DISK (DISC):

See Disk Storage

MAGNETIC DRUM:

See Drum

MAGNETIC HEAD:

A transducer for converting electric variations into magnetic variations for storage on a magnetic media or for reconverting energy so stored into electric energy: It may also be used for erasing the stored energy. Example: Used for recording and reading to and from disks and magnetic tapes.

MAGNETIC MEDIUM:

Any medium designed for data storage using magnetic pulses to record information, such as magnetic tape, diskettes or disks.

MAGNETIC STORAGE:

A device that utilizes the magnetic properties of a material to store information: such as memory, disk, drum, magnetic tape, etc.

MAJORDOMO:

One of the common types of E-mail discussion lists.

MAIL LIST (Mailing List):

Usually an automated system that allows people to send E-mail to one address, then the message is copied and sent to all of the other subscribers on the mail list. This allows individuals who have many different kinds of E-mail access to participate in group discussions.

MAIL BOMB:

Excessively large e-mail, typically many thousands of messages, or one large message sent to a user's e-mail account, for the purpose of crashing the system, or preventing genuine messages from being received.

MAIL BRIDGE:

Mail gateway that forwards e-mail between two or more networks while ensuring that the messages it forwards meet certain administrative criteria. A mail bridge is a specialized form of mail gateway that enforces an administrative policy with regard to what mail it forwards.

MAIL EXPLORER:

Part of an e-mail delivery system that allows a message to be delivered to a list of addressees. Mail exploders are used to implement mailing lists. Users send messages to a single address, example, sams@lonehost.edu, and the mail exploder takes care of delivery to the individual mailboxes in the list.

MAIL GATEWAY:

Machine that connects two or more e-mail systems, especially dissimilar mail systems on two different networks, and transfers messages between them. Sometimes the mapping and translation can be complex, and generally it requires a store-and-forward scheme where the message is received from one system completely before it is transmitted to the next system after suitable translations.

MAINFRAME:

When referencing a computer it is the central processor portion of a computer system. It contains the main storage; arithmetic unit and special register group. Normally the input/output portion and in some instances memory storage would not be included.

MAIN NETWORK ADDRESS:

A term used in the IBM System Network Architecture (SNA), which defines the Logical Unit (LU) and Network Address, within the Virtual Telecommunication Access Method (VTAM).

MAIN STORAGE:

Usually refers to the fastest storage media (memory) from which instructions are executed.

MAINTAINABILITY:

The ability of a part, subsystem, or system to continue to operate:  Or to be restored to a specified level of operation, when the maintenance is performed in accordance with recommended procedures.

MAKE CHANGES:

The Macintosh style permission that gives users the right to make changes to a folder's contents; example: modifying, renaming, moving, creating, and deleting files. When AppleTalk network integration translates access privileges into permissions, a user who has the Make Changes privilege is given Write and Delete permissions.

MALICIOUS CODE:

A piece of code designed to damage a system or the data within a system, or to prevent the system from being used in its normal manner.

MALWARE:

A generic term used to describe malicious software such as: viruses, Trojan horses, malicious active content, etc.

MAN:

Metropolitan Area Network - A communication network that serves an urban area

MAN-IN-THE-MIDDLE:

Form of active wiretapping attack in which the attacker intercepts and selectively modifies communicated data in order to masquerade as one or more of the entities involved in a communication association.

MANAGED OBJECT:

In network management, a network device that can be managed by a network management protocol

MANAGEMENT SERVICES:

SNA functions distributed among network components to manage and control an SNA network

MANCHESTER CODE, MANCHESTER ENCODING:

Refers to a binary signaling mechanism where each bit period is divided into two complementary halves, combining data and clock pulses.

Digital coding scheme, used by IEEE 802.3 and Ethernet, in which a mid-bit-time transition is used for clocking, and a 1 bit is denoted by a high level during the first half of the bit time.

MANUFACTURING AUTOMATION PROTOCOL:

See MAP

MAP:

Manufacturing Automation Protocol: Refers to a General Motors Corporation token passing bus designed for a factory environment and is similar to IEEE 802.4

MAPI:

See Messaging Application Programming Interface

MAPPED DRIVES:

Network drives assigned local drive letters and locally accessible. For example, the directory path \\MAIN\JohnDoe\ might be mapped as drive G: on a computer.

MARGINAL RELAY:

A relay designed to operate only on a specified current flow, which is greater than the normal current flow. Or in maintenance terms: a faulty or problem relay causing abnormal conditions.

MARK:

1) A digital signal, normally a positive current/voltage level or a binary "1."

2) In telegraph communications, a mark indicates the closed, current -flow condition.

3) When used in data communication, a mark indicates a no-traffic state for asynchronous transmission.

4) A mark may also indicate the idle condition, contrast with space. See mark-hold.

MARK-HOLD:

The transmission of a steady mark (1 bit condition) to indicate a normal no- traffic line condition

MARK SENSE:

The process of sensing the pencil marks (information) on preprinted cards.

MARK-TO-SPACE TRANSMISSION:

The process of switching from a mark pulse (1 bit) to a space pulse (0 bit): usually a normal transmission activity.

MARS:

Multicast Address Resolution Server: Mechanism for supporting IP multicast. A MARS serves a group of nodes (cluster); each node in the cluster is configured with the ATM address of the MARS. The MARS supports multicast through multicast messages of overlaid point-to-multipoint connections or through multicast servers.

MARTIAN:

Humorous term applied to packets that turn up unexpectedly on the wrong network because of bogus routing entries. Also used as a name for a packet that has a bogus (non-registered / ill-formed) Internet address.

MASER:

1) Microwave Amplification by Simulated Emission of Radiation - A device designed to generate a microwave signal with low-noise properties.

2) A device capable of amplifying or generating radiation. Maser amplifiers are (were) used in satellite communication ground stations to amplify weak signals received from satellites.

MASHUP:

A web page or site made by automatically combining content from other sources, usually by using material available via RSS feeds and/or REST interfaces.

MASK:

A bit combination used to determine which part of an address refers to the network or the subnet and which part refers to the host.

MASQUERADE ATTACK:

Type of attack in which one system entity illegitimately assumes the identity of another entity

MASTER BOOT RECORD (MBR):

The 340-byte program (Partition Table) located in the master boot sector. This program reads the partition table, determines what partition to boot and transfers control to the program stored in the first sector of that partition. There is only one master boot record on each physical hard disk.

MASTER BOOT SECTOR:

The first sector of a hard disk: This sector is located at sector 1, head 0, track 0. The sector contains the master boot record.

MASTER BOOT SECTOR VIRUS:

‘Master Boot Record Virus’: Master boot sector viruses infect the master boot sector of hard disks, although they spread through the boot record on floppy disks. The virus stays in memory, waiting for DOS to access a floppy disk. It then infects the boot record on each floppy disk DOS accesses.

MASTER CLOCK:

A synchronizing timing signal or signal mechanism used by all stations in a network or any other system, as required.

MASTER CONTROL PORT:

A physical interface on a MPLS LSC that is connected to one end of a slave control link

MASTER FILE TABLE (MFT):

An NTFS (New Technology File System) file on NTFS formatted volumes that contain information about each file and folder in the volume. The MFT is the first file in an NTFS volume.

MASTER GROUP (MG):

A term used in Frequency Division Multiplexing (FDM) where 10 super-groups (600 voice frequency channels) would be bundled and occupy adjacent multiple frequency bands in the transmission spectrum (channel).

MASTER SERVER:

An authoritative DNS server for a zone: Master servers can vary and are one of two types (primary or secondary masters), depending on how the server obtains its zone data.

MASTER STATION:

Three examples: A monitor station, used in LAN token-passing ring environments allowing recovery from error conditions, such as busy, duplicate or lost tokens; the main unit that controls and polls the nodes in a multipoint circuit; the unit that controls the slave station in a point-to-point circuit.

MATE:

Modular AUTODIN Terminal Equipment

MATIP:

Mapping of Airline Traffic over IP: A standard defined in RFC 2351 for transporting airline reservation, ticketing, and messaging traffic over TCP/IP (Transmission Control Protocol / Internet Protocol).

MATRIX:

An array of elements, used within the scientific calculations performed on a computer; in switching technology, the juncture/configuration of input and output leads.

MATV:

Master Antenna TV: A mini cable system relaying the broadcast channels usually to a block of homes or a small housing community

MAU:

Media Attachment Unit: Device used in Ethernet and IEEE 802.3 networks: Provides the interface between the AUI port of a station and the common medium of the Ethernet. The MAU, which can be built into a station or can be a separate device, performs physical layer functions, including the conversion of digital data from the Ethernet interface, collision detection, and injection of bits onto the network; may be referred to as a Media Access Unit (MAU) or a transceiver. In Token Ring, a MAU is known as a Multi-Station Access Unit (MSAU). See Media Access Unit or Multi-station Access Unit or Medium Attachment Unit

mbps:

Megabits per second, 1,000,000 bits/sec

MAXIMIZE:

To enlarge a window to its largest size by clicking the Maximize button, at the right of the title bar, or by pressing ALT+SPACEBAR and then pressing X.

MAXIMUM BURST:

Specifies the largest burst of data above the insured rate that will be allowed temporarily on an ATM PVC without being dropped by the traffic policing function; it may exceeds the maximum rate. This excess traffic will be allowed only temporarily; normally the average traffic source needs to be within the maximum rate; specified in bytes or cells.

MAXIMUM RATE:

Maximum total data throughput allowed on a given virtual circuit, equal to the sum of the insured and uninsured traffic from the traffic source. The uninsured data might be dropped if the network becomes congested. The maximum rate, which cannot exceed the media rate, represents the highest data throughput the virtual circuit will ever deliver, measured in bits or cells per second.

MAXIMUM TRANSMISSION UNIT:

Maximum packet size, in bytes, that a particular interface can handle

Mb:

Megabit: 1,000,000 bits.

M BIT:

An X.25 Packet Network bit used to notify the receiver that all data from the sender has been transmitted.

MBONE:

Multicast Backbone: Multicast backbone of the Internet. MBONE is a virtual multicast network composed of multicast LAN(s) and the interconnecting point-to-point tunnels.

MBR:

See: Master Boot Record

MBS:

1) Megabytes per second, 1,000,000 bytes/sec

2) Maximum Burst Size: In an ATM signaling message, burst tolerance is conveyed through the MBS, which is coded as a number of cells. The burst tolerance together with the SCR and the GCRA determine the MBS that can be transmitted at the peak rate and is still in conformance with the GCRA.

MC:

Mode Change: A special even-parity character used only in Magnetic Tape or off-line encrypted messages.

MCA:

Micro Channel Architecture: Bus interface commonly used in PC(s) and some UNIX workstations and servers.

MCB:

Message Control Block: Contains message identification and other internal system information.

MCDV:

Maximum Cell Delay Variation: In an ATM network, the maximum two-point CDV objective across a link or a node for the specified service category. One of four link metrics exchanged using PTSP(s) to determine the available resources of an ATM network. There is one MCDV value for each traffic class.

MCS:

Main Core Storage or microsecond

MCLR:

Maximum Cell Loss Ratio: In an ATM network, the maximum ratio of cells that do not successfully transit a link or node compared to the total number of cells that arrive at the link or node. One of four link metrics exchanged using PTSP(s) to determine the available resources of an ATM network. The MCLR applies to cells in the CBR and VBR traffic classes whose CLP bit is set to zero.

MCNS:

Multimedia Cable Network System Partners Ltd: Consortium of cable companies providing service to the majority of homes in the United States and Canada. This consortium uses a standard with the goal of having interoperable cable MODEM(s).

MCR:

Minimum Cell Rate: Parameter defined by the ATM Forum for ATM traffic management. MCR is defined only for ABR transmissions, and specifies the minimum value for the ACR.

MCTD:

Maximum Cell Transfer Delay: In an ATM network, the sum of the MCDV and the fixed delay component across the link or node. One of four link metrics exchanged using PTSP(s) to determine the available resources of an ATM network. There is one MCTD value for each traffic class.

MD:

Mediation Device: Device that provides protocol translation and concentration of telemetry information originating from multiple network elements and transport to an OSS.

MDF:

Main Distribution Frame

MD5:

Message Digest 5: A one-way hashing algorithm that produces a 128-bit hash. Both MD5 and Secure Hash Algorithm (SHA) are variations of MD4 and are designed to strengthen the security of the MD4 hashing algorithm. Cisco uses hashes for authentication within the IP-Sec framework. Also used for message authentication in SNMP v.2. MD5 verifies the integrity of the communication, authenticates the origin, and checks for timeliness.

MDL:

The Cisco Message Definition Language: A high-level language used to specify protocols and protocol conversion operations on the VSC.

MDN:

Message Disposition Notification: Message returned to the originator of an e-mail message indicating that the e-mail message has been opened. Specifications for MDN are described in RFC 2298.

MDS:

Message Delivery Service: The facilities used by ICM nodes to communicate with each other. The MDS plays a key role in keeping duplex components synchronized.

MDT:

Message Distribution Terminals: Narrative message terminals processing classified and unclassified messages directly connected with two Switching Centers.

MEAN TIME TO FAILURE (MTTF):

The average time period the system, or a related component, functions without a failure.

MEAN TIME BETWEEN FAILURES (MTBF):

See MTBF

MEAN TIME TO REPAIR (MTTR):

See MTTR

MECL:

Motorola Emitter Coupled Logic: Solid state electronics

MEDIA:

1) Any fixed or removable objects that store computer data: Examples include: hard disks, floppy disks, tapes and compact discs.

2) Various physical environments through which transmission signals pass. Common network media include twisted-pair, coaxial, and fiber-optic cable, and the atmosphere; microwave, laser, and infrared transmission.

MEDIA ACCESS CONTROL:

See MAC

MEDIA ACCESS UNIT (MAU):

A device used in Ethernet networks to transmit signals from the Media Access Control (MAC) onto the network medium. Synonym: Transceiver (transmitter/receiver)

MEDIA GATEWAY:

A gateway that supports both bearer traffic and signaling traffic

MEDIA GATEWAY CONTROLLER:

Another term for call agent

MEDIA INTERFACE CONNECTOR:

FDDI standard connector

MEDIA RATE:

Maximum traffic throughput for a particular media type

MEDIA STREAM:

A single media instance, for example: an audio stream.

MEDIUM:

The material / components used to record or transmit data

MEDIUM ATTACHMENT UNIT (MAU):

A transceiver (transmitter-receiver): Provides the necessary electrical or optical connections between the computer and the designated LAN (Local Area Network) media. A MAU typically supports only one type of network medium; therefore, different MAU choices are available to support different media.

MEGA / mega:

An acronym for one million

MEGABYTES (MB):

One million bytes

MEL CAS:

Mercury Exchange Limited (MEL) Channel Associated Signaling: A voice signaling protocol used primarily in the United Kingdom.

MEMORY:

An organization of storage elements used for the storage and retrieval of information. Examples of high-speed memory, over the years, would be magnetic core memory, semiconductor memory and solid state memory (chips). The rapid or high-speed (solid state) memory would be used for program instructions and the data being operated on at the moment. Other information would be stored in secondary memory, such as, disks or Magnetic tape and sometimes in secondary semi conductor memory.

MEMORY ADDRESS:

A portion of computer memory that can be allocated to a device or used by a program or the operating system: Devices are usually allocated a range of memory addresses.

MEMORY-RESIDENT VIRUS:

A memory-resident virus stays in memory after it executes and infects other files when certain conditions are met. In contrast, non-memory-resident viruses are active only while an infected application runs.

MESH:

Network topology in which devices are organized in a manageable segmented manner with many, often redundant, interconnections strategically placed between network nodes.

MESSAGE:

1) Data communication document containing information

2) Several packets that form a complete transmission.

3) Application layer (Layer 7) logical grouping of information, often composed of a number of lower-layer logical groupings, such as packets

MESSAGE FORMAT:

Rules for the placement (order) of portions of a message: Such as message heading (header), numbering, priority, address(s), text and end of message.

MESSAGE HEADER:

The address part of a message: including other control information, appearing before the text and following the Transmission Identifier line (TI). Headers are formatted differently for teletypewriter and other data media, but basically the header is divided into three parts: Header data up to and including the Start-of-Routing sequence, the Routing Indicator(s) (address) field and the Security line. The Precedence Field is included in the first part of the Header.

MESSAGE PRECEDENCE:

Message precedence (importance) is assigned by the originator, which determines the speed of service the message will receive during system processing. The precedence character(s) is included in the header section following the message SOM. The message precedence will determine the order of delivery when messages must compete for channel transmission time.

MESSAGE QUEUING:

In a store and forward system messages accepted for delivery are linked or queued to the output channel(s) as determined by the routing indicator(s). These messages are normally queued for delivery on a First-In, First-Out (FIFO) basis. Exceptions may occur based on the priority of the message or other conditions.

MESSAGE RETRIEVAL:

The capability to retrieve a message some time after it has been processed by the communications processor. In AUTODIN this was accomplished initially through the use of the History and Journal magnetic tapes and later from magnetic disk (mass Memory Units).

MESSAGE ROUTING:

Selecting a path (channel / terminal) for a message destination

MESSAGE UNIT:

Unit of data processed by any network layer

MESSAGE SWITCH / SWITCHING:

A system and/or device (node) that processes messages (receives, stores and transmits), which would include store and forward, historical data, and processing requirements.

MESSAGE TELEPHONE SERVICE (MTS):

The official designation for tariffs covering toll telephone service

MESSAGE TRANSFER PART:

A part of a common channel signaling system that transfers messages, error control and link security related to the transfer (protocols) of telephony networks.

MESSAGE UNIT (MU):

A local dial telephone charging plan that is time and distance sensitive

MESSAGING APPLICATION PROGRAMMING INTERFACE (MAPI):

Microsoft's standard for the applications interface to e-mail.

MESSENGER SERVICE:

A service that sends and receives messages sent by administrators or ‘Alerter’ service

META:

Prefix meaning ‘information about’

META TAG:

A specific kind of HTML (Hypertext Markup Language) tag that contains information not normally displayed. Meta tags contain information about the page itself (about the subject). A typical use of Meta tags is to include information for Search Engines to help them better categorize a page.

About the only way to view the Meta tags in a page is to look at the page source code.

METADATA:

Data about data: For example: the title, subject, author, and size of a file constitute the files metadata.

METAFILE:

A graphics format that combines the features of bitmap and vector graphics: Common types of metafile formats are CGM, Corel Draw CDR files, encapsulated Postscript-EPS files, Adobe Illustrator, Word Perfect Graphics WPG files, PICT, and RTF.

METASIGNALING:

Process running at the ATM layer that manages signaling types and virtual circuits

METROPOLITAN AREA NETWORK:

A communication network that serves an urban area

MF:

Multi-frequency Tones: Made of 6 frequencies that provide 15 two-frequency combinations for indicating digits 0 through 9 and KP/ST signals.

MFT:

Multi-Flex Trunk Module

MG:

1) Motor Generator: Some computer systems utilize motor generators as an interface between the commercial AC (alternating Current) power and the computer and other related equipment. This shields the computer equipment from small intermittent power fluctuations.

2) Media Gateway: The standard generic term for a gateway.

3) See Master Group

MGC:

Media Gateway Controller: Industry standard generic term for the VSC

MGC SWITCHOVER:

The rerouting of traffic by the signaling gateway as required, and requested by the MGC(s), between related MGC(s) in the event of failure or unavailability of the currently used MGC. The traffic is rerouted from the primary MGC to the backup MGC.

MGCP:

Media Gateway Control Protocol: A merging of the IPDC and SGCP protocols

MHD:

Moving Head Disc (drive) (replaced the magnetic tape drives). Each disk capacity was 19 heads, 18 sectors and 840 cylinders (like groves of on an LP). Each sector held seven line blocks.

MHDC:

Moving Head Drive Controller: A controller designed for IBM drives.

MHDTC:

Moving Head Disk Transfer Channel

MHP:

Multimedia Home Platform: A set of common Application Programming Interfaces (API) designed to create an operating system that provides a level playing field for broadcasters and consumer-electronics manufacturers. The goal is to provide all DVB-based terminals (TV, and multimedia PC) full access to programs and services built on the DVB Java (DVB-J) platform.

MHS:

Message Handling System: ITU-T X.400 recommendations that provide for message handling services for communications between distributed applications. NetWare MHS is a different entity that also provides message-handling services.

Mhz:

Megahertz (Hz), one million Hertz (cycles per second); A unit equal to one million cycles per second.

MIB:

Management Information Base: Database of network management information that is used and maintained by a network management protocol, such as SNMP or CMIP. The value of a MIB object can be changed or retrieved using SNMP or CMIP commands, usually through a GUI network management system. MIB objects are organized in a tree structure that includes public (standard) and private (proprietary) branches.

MIC:

Media Interface Connector: FDDI standard connector

MICA:

MODEM ISDN Channel Aggregation: MODEM module and card used in the Cisco AS5300 universal access servers. A MICA MODEM provides an interface between an incoming or outgoing digital call and an ISDN telephone line; the call does not have to be converted to analog as it does with a conventional MODEM on the analog telephone line. Each line can accommodate up to 24 (T1) or 30 (E1) calls.

MICR:

Magnetic Ink Character Recognition: Machine recognition of characters printed with magnetic ink.

MICRO CHANNEL ARCHITECTURE:

See MICA

MICRO-SEGMENTATION:

Division of a network into smaller segments, usually with the intention of increasing aggregate bandwidth available to network devices

MICROCODE:  

Translation layer between machine instructions and the elementary operations of a computer: Microcode is stored in ROM and allows the addition of new machine instructions without requiring that they be designed into electronic circuits when new instructions are needed.

MICROCOM NETWORKING PROTOCOL (MNP):

A proprietary error correcting and compression protocol for MODEM(s) developed by Microcom. See MNP Levels 2 through 10.

MICROCOMPUTER:
Refers to a small desktop or laptop computer (PC)

MICROFILTERS:

1) Used to protect the DSL signal from being distorted by any signal noise from the voice service, allowing both voice and data to share common inside wiring.

2) Device that prevents data frequencies, intended for a data device, such as a router, from traveling over the telephone line and interfering with telephone calls.

MICROPROCESSOR:

The microprocessor handles the logic operations in a computer, such as adding, subtracting, multiplying, etc. A set of instructions in the chip design controls the microprocessor, but different applications can give instructions to the microprocessor as well. Today Chip speeds are measured in megahertz (MHz) or gigahertz (GHz. Operating speed is influenced by many factors, such as the design of the software and hardware, the operating system, devices and communication line speeds. Intel manufactured the first microprocessor, the 8080. Other early microprocessors included Motorola's 6800 and Rockwell's 6502.

MICROPROGRAMMING:

Normally refers to the practice of burning a program into ROM (Read Only Memory chip) to carry out functions that would otherwise be contained on a magnetic storage device.

MICROSECOND:

One millionth of a second

MICROSOFT EXCHANGE:

A commercial-off-the-shelf software product that represents the NAVSEA DMS product set.

MICROSOFT RESERVED (MSR) PARTITION:

A required partition on every GUID Partition Table (GPT) disk: System components can allocate portions of the MSR partition into new partitions for their own use. For example: when a user converts a basic GPT disk to dynamic, the system allocates a portion of the MSR partition to be used as the Logical Disk Manager (LDM) metadata partition. The MSR partition varies in size based on the size of the GPT disk. For disks smaller than 16 GB, the MSR partition is 32 MB. For disks larger than 16 GB, the MSR partition is 128 MB. The MSR partition is not visible in Disk Management, and a user cannot store data on the MSR partition or delete it.

MICROWAVE COMMUNICATIONS SYSTEM:

Microwave can be used for short and/or long haul communications. The system sends analog signals from tower to tower (repeater stations), using frequencies typically between 890 megahertz (Hz) and 20 gigahertz. Microwave communications first came into widespread use to connect the Television Broadcast stations with network studios and to connect parts of the nationwide long-distance telephone network. Both applications demanded extremely high reliability. Between a network headquarters on the East Coast and a television broadcast station located in the mid west area, there may be 30 to 40 microwave repeaters stations because of the line of sight requirement. Microwave frequencies are also used to communicate to and from satellites, which is a non-terrestrial application and the range of transmission is fairly unrestricted. One major advantage of microwave signals is that they do not require cable, but they also have the distinct disadvantage of only traveling in straight lines or line-of-sight between repeaters and the final terminal.

MID:

Message Identifier: In ATM, used to identify ATM cells that carry segments from the same higher-layer packet.

MIDI:

Musical Instrument Digital Interface

MID-LEVEL NETWORK:

Makes up the second level of the Internet hierarchy: They are the transit networks that connect the sub networks to the backbone networks.

MIDSPLIT:

Broadband cable system in which the available frequencies are split into two groups: one for transmission and one for reception.

MIGRATION:

The movement of a system or application from its current environment to a defined technical environment (target)

MII:

Media Independent Interface: Standard specification for the interface between network controller chips and their associated media interface chip(s). The MII automatically senses 10- and 100-MHz Ethernet speeds.

MILLISECOND:

One thousandth of a second

MILLIWATT:

One thousandth of one watt

MIME:

Multipurpose Internet Mail Extensions: Originally a standard for defining the types of files attached to standard Internet mail messages. The MIME standard has come to be used in many situations where one computer programs needs to communicate with another program to determine what kind of file is being sent.

Standard for transmitting non-text data or data that cannot be represented in plain ASCII code, in Internet mail; such as binary, foreign language text (i.e. Russian or Chinese), audio, or video data. MIME is defined in RFC 2045.

MIN:

Mobile Identification Number: A 10-digit number derived from your phone's number

MINICOMPUTER:

A complete small to medium scale computer

MINIMIZE:

To reduce a window to a button on the taskbar by clicking the Minimize button at the right of the title bar, or by pressing ALT+SPACEBAR and then pressing N.

MIP:

Multi-Channel Interface Processor: Interface processor on the Cisco 7000 series routers that provides up to two channel T1 or E1 connections via serial cables to a CSU. The two controllers on the MIP can each provide up to 24 T1 or 30 E1 channel-groups, with each channel-group presented to the system as a serial interface that can be configured individually.

MIPR:

Military Interdepartmental Purchase Request: A procurement document (DD Form 448) which is used to request supplies and services from the DMS contract.

MIPS:

Millions of Instructions Per Second: One of several measurements for computer processing power

MIRROR:

Generally speaking, ‘to mirror’ refers to the storage of an exact copy of something. Probably the most common use of the term on the Internet refers to ‘mirror sites’ which are Web sites, or FTP (File Transfer Protocol) sites that maintain copies of material originated at another location, usually in order to provide more widespread access to the resource. For example, one site might create a library of software, and 3 other sites might maintain mirrors of that library.

MIRRORED VOLUME:

A fault tolerant volume that duplicates data on two physical disks:. A mirrored volume provides data redundancy by using two identical volumes, which are called mirrors, to duplicate the information contained in the volume. A mirror is always located on a different disk. If one of the physical disks fails, the data on the failed disk becomes unavailable, but the system continues to operate in the mirror on the remaining disk. A user can create mirrored volumes only on dynamic disks.

MISSI:

Multi-level Information System Security Initiative: The National Security Agency (NSA) initiative to provide products for DoD.

MISSION SUPPORT SERVICES:

Services that implement external Command mission support requirements for messaging and file transfer.

MIX:

Multi-service Interchange

MJU:

Multipoint Junction Unit: A device used to provide multipoint Digital Service.

ML-188C:

The military shielded interface standard, the equivalent to RS-232 between a MODEM and line controller.

MLP:

Multilink PPP: Method of splitting, recombining, and sequencing data-grams across multiple logical data links

MLS:

Multilayer Switching

MM FIBER:

Multimode Fiber: A fiber-optic medium in which light travels in multiple modes

MMDS:

Multi-channel Multipoint Distribution Service: MMDS is comprised of as many as 33 discrete channels that are transmitted in a pseudo random order between the transmitters and the receivers. The FCC allocated two bands of frequencies for each Basic Trading Area (BTA): 2.15 to 2.161 GHz and 2.5 to 2.686 GHz.

MMF:

Multi-Mode Fiber: Optical fiber supporting the propagation of multiple frequencies of light

MML:

Man-Machine Language: Industry standard command line language used to manage telecommunications network elements.

MMLS-RP:

Multicast MLS-Route Processor: Routing platform running Cisco IOS software that supports IP multicast MLS. The MMLS-RP interacts with the IP multicast routing software and updates the MLS cache in the MMLS-SE.

MMLS-SE:

Multicast MLS-Switching Engine: Catalyst 5000 series switch with hardware that supports IP multicast MLS. The MMLS-SE provides layer 3 LAN-switching services.

MMoIP:

Multimedia Mail over IP

MMoIP DIAL PEER:

Multimedia Mail over IP Dial Peer: Dial peer specific to Store and Forward Fax. The MMoIP Dial Peer is the vehicle used to assign particular line characteristics, such as a destination telephone number, to the connection between the Cisco router or the access server and the SMTP mail server during on-ramp faxing.

MMP:

Multi-chassis Multilink PPP: Extends MLP support across multiple routers and access servers. MMP enables multiple routers and access servers to operate as a single, large dial-up pool, with a single network address and an ISDN access number. MMP correctly handles packet fragmenting and reassembly when a user connection is split between two physical access devices.

MMS:

Multimedia Messaging Service: Similar to SMS (Short Messaging System), but in addition to plain text, MMS messages may include multimedia elements such as pictures, video and audio. These multimedia elements are included in the message, not as attachments as with e-mail.

MMU:

Mass Memory Unit (storage): Disk or Solid State Memory

MNEMONIC:

As used in data communications: A symbolic routing designator consisting of alphabetic or numeric characters or a combination of alphabetic and numeric characters. See Alphanumeric.

MNP:

See Microcom Networking Protocol

MNP Levels 2, 3, and 4:

Microcom Networking Protocol: Provides three progressive levels of error-correcting performance.

MNP Levels 5 and 7:

Microcom Networking Protocol: Provides two progressive classes of data compression compatible with MNP Level 4 error correction; MNP Level 5 offers 2-to-1 data compression for 1200 bps and higher MODEMs; MNP Level 7 offers 3-to-1 data compression.

MNP Levels 6 and 8:

Microcom Networking Protocol: Provides error correction and compression protocols for half-duplex MODEMs.

MNP Level 9:

Microcom Networking Protocol: Provides "turbo" mode error-correction and data compression.

MNP Level 10:

Microcom Networking Protocol: A Protocol providing error-correction and compression for ‘dirty’ telephone lines.

MO:

‘Main Operation’ Instruction: (CDP/ICCDP main software program instruction)

MOO:

Mud, Object Oriented: One of several kinds of multi-user role-playing environments

MOD PERL:

An add-on for the Apache web server software, MOD PERL makes it possible to use the ‘Perl’ language to add new features for the Apache server, and to increase the speed of ‘Perl’ applications by as much as 30 times.

MOBILE IDENTIFICATION NUMBER (MIN):

A 10-digit number derived from a user’s cell phone number

MOBILENET:

A network composed of some portable devices that communicate with other network devices.

MODE:

A style or method of operation

MODE I:

A synchronous transmission mode using the ASCII eight-bit (seven data bits plus parity) code set; the transmitted characters are synchronized by utilizing the ASCII sync characters.

MODE II:

This mode is an uncontrolled teletypewriter operation with full duplex capability (simultaneous transmission in both directions). Normally uses the Baudot or ASCII code. In the uncontrolled mode there is not any control over the sending or receiving functions. The transmission of data may begin at any time and the receiving equipment must be in an operational mode at all times.

MODE III:

This mode is a Mode 1 operation with data transmission in only one direction.

MODE IV:

This mode is an uncontrolled teletypewriter operation with data transmission in only one direction.

MODE V:

This mode is an asynchronous operation (transmission) normally using the ASCII or Baudot (ITA 2) code set. A start (space) bit and a stop (mark) bit are required. Each character transmitted begins with a start bit and ends with a stop bit. The start bit is usually one bit long (duration) and the stop bit is from 1.5 to 2 bits long. Therefore an 8-bit ASCII code character would become a 10.5 to 11 bit character. The Baudot character would become a 7.5 (7.42) bit character. The start bit trips the teletypewriter clutch mechanism allowing the following bits to be decoded (character definition) and the stop bit latches the clutch stopping the mechanism. This would repeat for each character received. Normal idle line condition would be a positive (mark) voltage condition.

Mode V may function in either a controlled or uncontrolled environment.

MODEM:

Modulator-Demodulator (data transmission device) - There has been many types of MODEM's over the years and the capability and efficiency has greatly improved. Thirty years ago 9600 bps was a high speed MODEM. Today 56.6 kbps is the norm. Basically each computer system line requires a MODEM in order to operate on a telephone line using analog signals. The MODEM converts the digital signal (pulses) to an analog signal (waveform 'AC'), cloning a voice analog signal, and, in turn, converts an analog signal to a digital signal. Of course a digital telephone line would alter this requirement. Refer to MODEM STANDARD and V. STANDARDS for additional information.

MODEM COMPRESSION:

A technique used to reduce the number of characters transmitted without losing data content. The transmitting MODEM compresses the data and the receiving computer or MODEM decompresses the data back to its original state.

MODEM ELIMINATOR:

A device designed to connect two Data Terminal Equipment (DTE) devices. MODEM Eliminators perform signal conversions and may provide the necessary clocking.

MODEM, HIGH SPEED:

Refers to a MODEM operating in excess of 4800 bps on a voice-grade line

MODEM, MULTIPORT:

A MODEM - Multiplexer combination that allows two or more Data Terminal Equipment (DTE) devices to be connected to the same line, also known as Split Stream Modem.

MODEM, QUICK TURNAROUND:

Refers to a MODEM designed to reduce the turn around time in half-duplex operation.

MODEM SHORT HAUL (SHM):

See Line Driver.

MODEM, SPLIT STREAM:

See MODEM, Multi-port.

MODEM STANDARDS:

XMODEM – A protocol for transferring files during direct dial-up communications. XMODEM has basic error checking to ensure that information isn't lost or corrupted during transfer; it sends data in 128-byte blocks. XMODEM CRC uses a more reliable error-correction scheme, and XMODEM -1K transfers data faster by sending it in 1,024-byte blocks.

YMODEM - A protocol for transferring files during a direct dial-up communications. YMODEM sends data in 1,024-byte blocks. However, it doesn't work well on noisy phone lines, unlike its successor, ZMODEM. YMODEM - Batch can send several files in one session. YMODEM-G drops software error correction, which speeds up the process because error correction is performed elsewhere.

ZMODEM – A more reliable protocol for transferring files using dial-up connections. A ZMODEM operates at higher speed rates and provides error-checking routines. Also it can resume a file transfer after a break in communications. Refer to V. STANDARDS for additional information.

MODEM, WIDE BAND:

Refers to a MODEM designed to achieve bit speeds greater than 19.2 kbps or 56 kbps. Originally this MODEM required a Wide band circuit (channel), but now can operate over a voice grade channel.

MODULARITY:

An approach to developing hardware or software that breaks projects into smaller units or modules, and these modules are designed as stand alone units or can also work with other sections (modules) of the program. The same module can perform the same task in another or several other programs or components.

MODULATION:

Modulation refers to the process of transforming digital data into analog signals for transmission. When transferring data over phone lines, for example, a MODEM modulates the data into audible tones within frequencies between 0 Hz and 4 KHz. Once the data reaches its intended destination, another MODEM demodulates the signal back into digital data. Cable TV networks also use modulation techniques to transfer data. But instead of audible tones, digital modulation schemes are used that greatly increase the amount of data that can be sent.

MODULE:

Most used definitions: a program portion, unit or subdivision written to perform one or more functions, or a circuit card for a hardware device (computer, peripheral, terminal, etc.).

MODULO:

A term used to describe the maximum number of counter states, such as describing packet-switched parameters, packet number.

MONITOR:

A program or device used to observe an operation without interfering with the operation; or a console monitor printer

MONITOR STATION:

A device used in a Local Area Network (LAN) on ring networks to remove damaged packets and ensure the ring is intact.

MONOMODE FIBER:

Fiber-optic cabling with a narrow core that allows light to enter only at a single angle: Such cabling has higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width (a laser).

MONOPHONIC RINGTONES:

A series of sequential beeps at different frequencies: These sound like the beeping of a computer, and the tunes are simple because the phone can only produce one sound (beep) at a time.

MOP:

Maintenance Operation Protocol: Digital Equipment Corporation protocol that provides a way to perform primitive maintenance operations on DEC-net systems. For example, MOP can be used to download a system image to a diskless station.

MOSAIC:

Public-domain WWW browser developed at the NCSA

A term for the first WWW browser that was available for the Macintosh, Windows and UNIX, all using the same interface. Mosaic really started the popularity of the Web. The source-code to Mosaic was licensed by several companies and used to create many more Web browsers. Mosaic was developed at the National Center for Supercomputing Applications (NCSA). The first version was released in late 1993.

MOSPF:

Multicast OSPF: Intra-domain multicast routing protocol used in OSPF networks. Extensions are applied to the base OSPF Unicast protocol to support IP multicast routing.

MOSS:

MIME Object Security Services: Internet protocol that applies end-to-end encryption and digital signature to MIME message content, using symmetric cryptography for encryption and asymmetric cryptography for key distribution and signature.

MOTHERBOARD:

The motherboard is the largest printed circuit board in the computer. It generally houses the CPU chip, the controller circuitry, the bus, and sockets for additional boards, which are called daughter-boards. If you have a horizontal-style computer, the motherboard is generally the one at the bottom of the computer's box. If you have a tower-configuration box, it's along one of the vertical sides.

MOUNT:

To place a removable tape or disc into a drive

MOUNTED DRIVE:

A drive attached to an empty folder on an NTFS (New Technology File System) volume. A mounted drive functions the same as any other drive, but is assigned a label or name instead of a drive letter. The mounted drives name is resolved to a full file system path instead of just a drive letter. Members of the Administrators group can use Disk Management to create mounted drives or reassign drive letters.

MOUSEKEYS:

A keyboard feature that enables an individual to use the numeric keypad to move the mouse pointer and to click, double-click, and drag.

MOVES, ADD’S, CHANGES:

See MAC

MP:

Message Processor or Monitor Printer (system/console printer)

MPEG:

Moving Picture Experts Group: A committee that generates standards for digital video compression and audio; algorithms.

Standard for compressing video: MPEG1 is a bit stream standard for compressed video and audio optimized to fit into a bandwidth of 1.5 Mbps. MPEG2 is intended for higher quality video-on-demand applications and runs at data rates between 4 and 9 Mbps. MPEG4 is a low-bit-rate compression algorithm intended for 64-kbps connections.

MPL:

Multi-schedule Private Line: An AT&T tariff for a leased voice-grade line

MPLS:

Multi-protocol Label Switching: Switching method that forwards IP traffic using a label. This label instructs the routers and the switches in the network where to forward the packets based on pre-established IP routing information.

MPOA:

Multi-protocol over ATM: ATM Forum standardization specifying how existing and future network-layer protocols, such as IP, IPv6, AppleTalk, and IPX, run over an ATM network with directly attached hosts, routers, and multilayer LAN switches.

MP3 FILE:

Moving Picture Experts Group Audio Layer 3 File: MP3 files are highly compressed audio tracks, and are very popular on the Internet. MP3 files are not programs, and viruses cannot infect them. This file type has the extension MP3.

MQI:

Message Queuing Interface: International standard API that provides functionality similar to that of the RPC interface. In contrast to RPC, MQI is implemented strictly at the application layer.

MR:

MODEM Registrar: One of the suite of software products included in the Cisco Subscriber Registration Center (CSRC) product. MR is a policy-based cable MODEM management product that provides dynamic cable MODEM configuration.

MRM:

Multicast Routing Monitor: A management diagnostic tool that provides network fault detection and isolation in a large multicast routing infrastructure. It is designed to notify a network administrator of multicast routing problems in near real time.

MRP:

Multi-service Route Processor: A card that acts as a voice-and-data-capable router that can carry voice traffic over an IP network and can link small-to-medium-size remote Ethernet LANs to Central Offices (COs) over WAN links. The MRP has two slots that support WAN Interface Cards (WIC), Voice Interface Cards (VIC), or both in combination.

MROC:

Multi-Command Required Operational Capability

MS:

1) Message Store

2) Mobile Station: Refers generically to any mobile device, such as a mobile handset or computer that is used to access network services. GPRS networks support three classes of MS, which include the type of operation supported within the GPRS and the GSM mobile wireless networks. For example, a Class ‘A’ MS supports simultaneous operation of GPRS and GSM services.

MS-CHAP

Microsoft Challenge Handshake Authentication Protocol

MSA:

Metropolitan Statistical Area: An area defined by the US government for use in grouping census data and other statistics. MSA(s) include cities of at least 50,000 people or an urbanized area of at least 100,000 people and the counties that include these areas. Not all areas of the US are in an MSA. The FCC (Federal Communications Commission) uses these area definitions to license cellular telephone service carriers. The FCC often uses the term MSA to mean Metropolitan Service Areas; they are the same geographic areas. There are 306 regions of the US designated as MSA(s).

MSAU:

Multi-Station Access Unit: Concentrator to which all end stations in a Token Ring network connect. The MSAU provides an interface between the end stations (devices) and the Token Ring interface of a router.

MSB:

Most Significant Bit: Bit n-1 in an n bit binary number, the bit with the greatest weight. The first or leftmost bit when the number is written in the usual way.

MSC:

Mobile Switching Center: Provides telephony switching services and controls calls between telephone and data systems.

MSDL:

See Multi-rate Symmetric DSL

MS-DOS:

Microsoft Disk Operating System: An operating system used on all personal computers and compatibles. As with other operating systems, such as OS/2, it translates user keyboard and mouse inputs into operations the computer can perform. MS-DOS can be easily accessed by using the command prompt, while MS-DOS-based programs can be accessed through the use of shortcuts on the desktop.

MS-DOS ICON:

The icon at the left end of the title bar: Clicking this icon displays the System menu for the MS-DOS window.

MS-DOS BASED PROGRAM:

A program that is designed to run with MS-DOS and therefore may not be able to take full advantage of all Windows features.

MSI:

Medium Scale Integration (printed circuit electronics)

MSLT:

Minimum Scan Line Time: The time set by the receiving fax machine and sent to the sending machine during the initial handshaking. MSLT defines how much time the receiving machine requires to print a single scan line.

MSLT ADJUSTMENT:

Minimum Scan Line Time adjustment: An alternative to Scan Line Fix Up meant to eliminate fax failures caused by an excessive number of received page errors because of data loss. MSLT adjustment sets a minimum MSLT value that a receiving gateway communicates to a sending fax machine. This value overrides an MSLT of lesser value that is supplied by a receiving fax machine.

MS/ms/msec:

Millisecond: one-thousandth of a second

MSO:
Multiple Service Operator: Cable service provider that also provides other services, such as data and/or voice telephony.

MSU:

1) Multipoint Signaling Unit: A device used with test equipment to isolate and test portions of a Data-phone Digital Service (DDS) multipoint circuit.

2) MODEM Sharing Unit: A hardware device, most often a simple contention switch operating on RTS (Request to send) leads of Data Terminal Equipment (DTE) interfaces; permits only one terminal at a time to use the shared MODEM.

3) Message Switching Unit.

4) Message Signal Unit: SS7 message that carries call control, database traffic, network management, and network maintenance data in the Signaling Information Field (SIF)

MT:

Magnetic Tape

MTA:

1) Magnetic Tape Transfer Channel (1 or A)

2) Major Trading Area: An area consisting of two or more Basic Training Areas as defined by Rand McNally & Co: These large areas are used by the FCC to determine service areas for some PCS (Personal Communication Services) wireless licenses. The US is divided into 51 MTA(s).

3) Message Transfer Agent: OSI application process used to store and forward messages in the X.400 Message Handling System; equivalent to Internet mail agent.

4)  Mail Transfer Agent. Software that implements SMTP and provides storage for mail messages to be forwarded or delivered to a local user.

MTB:

Magnetic Tape Transfer Channel (2 or B)

MTBF:

Mean Time between Failures: The average time equipment is operational between failures.

MTP:

Message Transfer Part: Layers 1 (physical), 2 (data), and 3 (network) of the SS7 signaling protocol.

MTP1:

Message Transfer Part Level 1: SS7 architectural level that defines the physical, electrical, and functional characteristics of the digital signaling link

MTP2:

Message Transfer Part Level 2: SS7 architectural level that exercises flow control, message sequence validation, error checking, and retransmission.

MTP3:

Message Transfer Part Level 3: SS7 architectural level that provides messages between signaling points in the network, helping control traffic when congestion or failures occur.

MTS:

See Message Telephone Service

MTSO:

Mobile Telephone Switching Office: The office housing switches and computers to which all cell sites in an area are connected for the purpose of eventual connection to the PSTN (Public Switched Telephone Network). The MTSO handles the connection, tracking, status and billing of all wireless call activity in an assigned area.

MTT:
Magnetic Tape Transports (Magnetic Tape Stations)

MTTC:

Magnetic Tape Transfer Channel Control Unit

MTTF:

See Mean Time to Failure

MTTR:

Mean-Time-To-Repair: The average time needed to return a failed device or system to service.

The elapsed time between when a computer or device failure is reported to maintenance and the time that the computer or device is repaired and restored to full service

MTU:

Maximum Transmission Unit: Maximum packet size, in bytes, that a particular interface can handle.

MUD:

Multi-User Dungeon or Dimension: Refers to multi-user software (usually text based) simulation environments. Some are for fun others are used for serious software development, or education purposes, etc. A significant feature of most MUD(s) is that users can create projects that stay after they leave, which allows other users to interact, thus allowing a project to be built (completed) gradually and collectively.

MU-LAW:

North American companding standard used in conversion between analog and digital signals in PCM systems: Similar to the European a-law.

MULTIACCESS NETWORK:  

Network that allows multiple devices to connect and communicate simultaneously

MULTICAST:

Single packets copied by the network and sent to a specific subset of network addresses. These addresses are specified in the Destination Address Field.

MULTICAST ADDRESS:

Single address that refers to multiple network devices: Synonymous with group address.

MULTICAST BIT:

A designated bit used in the Local Area Network (LAN) environment, Ethernet addressing scheme, indicating a broadcast message.

MULTICAST FORWARD VCC:

VCC (Virtual Channel Connection) set up by the BUS to the LEC as a leaf in a point-to-multipoint connection.

MULTICAST GROUP:

Dynamically determined group of IP hosts identified by a single IP multicast address

MULTICAST ROUTER: 

Router used to send IGMP query messages on their attached local networks. Host members of a multicast group respond to a query by sending IGMP reports identifying the multicast groups to which they belong. The multicast router takes responsibility for forwarding multicast data-grams from one multicast group to all other networks that have members in the group.

MULTICAST SEND VCC:

In an ATM network, a bi-directional point-to-point VCC set up by an LEC to a BUS: One of three data connections defined by Phase 1 LANE

MULTICAST SERVER:

Establishes a one-to-many connection to each device in a VLAN; thus establishing a broadcast domain for each VLAN segment. The multicast server forwards incoming broadcasts only to the multicast address that correlate to the broadcast address.

MULTI-CHANNEL INTERFACE PROCESSOR (MIP):

Multi-Channel Interface Processor: Interface processor on the Cisco 7000 series routers that provides up to two channel T1 or E1 connections via serial cables to a CSU. The two controllers on the MIP can each provide up to 24 T1 or 30 E1 channel-groups, with each channel-group presented to the system as a serial interface that can be configured individually.

MULTIDOMAIN NETWORK:

Refers to an IBM System Network Architecture (SNA) based network consisting of two or more host systems, representing processing and control points.

MULTIDROP:

See Multipoint / Multi-drop

MULTIHOMED COMPUTER:

A computer that has multiple network adapters or that has been configured with multiple IP (Internet Protocol) addresses for a single network adapter

MULTIHOMED HOST:

Host attached to multiple physical network segments in an OSI CLNS network

MULTIHOMING:

Addressing scheme in IS-IS routing that supports the assignment of multiple area addresses

MULTI-INSTANCE OPTION:  

A DOCSIS option that can occur multiple times in an option set

MULTILAYER SWITCH:  

Switch that filters and forwards packets based on MAC addresses and network addresses: A subset of LAN switch.

MULTILEAVING:

A method of interspersing message blocks for various applications on a single line. Another -name: Interleaving.

MULTILINK DIALING:

  The combination of two or more physical communications links into a single logical link to increase the remote access bandwidth and throughput by using remote access Multilink.

   Based on the Internet Engineering Task Force (IETF) standard RFC 1990, Multilink combines analog MODEM paths, ISDN B-channels, and mixed analog and digital communications links on both the client and server computers. This increases the Internet and intranet access speed and decreases the amount of time the user is connected to a remote computer.

MULTILINK PPP:

Multilink Point-to-Point Protocol: This protocol is a method of splitting, recombining, and sequencing data-grams across multiple logical data links.

MULTIMODE:

Refers to a type of fiber optic light cable capable of propagating light signals of two or more wavelengths; May also be used to describe a multipurpose device.

MULTIPARTITE VIRUS:

Multipartite viruses use a combination of techniques including infecting documents, executable files and boot sectors. Most multipartite viruses first become resident in memory and then infect the boot sector of the hard drive. Once in memory, multipartite viruses may infect the entire system.

Removing multipartite viruses requires cleaning both the boot sectors and any infected files. Before attempting the repair, one must have a clean, write-protected Rescue Disk.

MULTIPLE ACCESS:

In satellite communications, the capability of a communications satellite to function as part of the communications linkage between more than a single pair of ground stations.

MULTIPLE ADDRESS MESSAGE:

A message containing more than one address, which will be delivered (transmitted) to more than one station (terminal).

MULTIPLE BOOT:

A computer configuration that runs two or more operating systems

MULTIPLE DOMAIN NETWORK:

SNA network with multiple SSCP(s)

MULTIPLEX / MULTIPLEXING / MULTIPLEXER:

The process of transferring data from several storage devices operating at low speed to one storage device operating at high speed. This is accomplished in such a manner that the high-speed device is not required to wait for each individual low speed device. The combined individual low speed device's data can then be transferred, bundled together, over a high-speed line. The combined low speed signals may also be transmitted simultaneously.

MULTIPOINT CONTROL UNIT:  

Endpoint on the LAN that provides the capability for three or more terminals and gateways to participate in a multipoint conference

MULTIPOINT JUNCTION UNIT (MJU):

See MJU

MULTIPOINT SIGNALING UNIT (MSU):

See MSU

MULTIPOINT / MULTIDROP:

Communications line with multiple cable access points; sometimes called a multipoint line.

A circuit or device that provides the capability for connecting several stations (terminals) on a common shared circuit (line); one station at a time, usually under central polling control, is allowed access to the line.

MULTIPOINT-UNICAST:

A process of transferring Protocol Data Units (PDU) when an endpoint sends more than one copy of a media stream to different endpoints: This might be necessary in networks that do not support multicast.

MULTIRATE SYMMETRIC DSL (MSDSL):

Symmetric DSL is capable of more than one transfer rate. The transfer rate is set by the service provider, typically based on the service (price) level.

MULTISTATION ACCESS UNIT (MAU):

A concentrator used in token-ring networks to connect multiple stations. The token-ring MAU, and an arrangement of internal relays, function as bypass switches and connect stations to form a complete electrical ring.

MULTI-VENDOR NETWORK:  

Network using equipment from more than one vendor’s: Multi-vendor networks pose many more compatibility problems than single-vendor networks.

MULTIPATHING:

Multi-pathing allows for two or more data paths to be simultaneously used for read/write operations, enhancing performance by automatically and equally dispersing data access across all the available paths.

MUSE:

Multi-User Simulated Environment: One kind of MUD

MUTANT:

See: Variant

MUTATING VIRUS:

A mutating virus changes, or mutates, as it progresses through its host files making disinfection more difficult. The term usually refers to viruses that intentionally mutate, though some experts also include non-intentionally mutating viruses.

MUX:

A contraction of the word Multiplex or Multiplexer

Equipment that enables several data streams to be sent over a single physical line. It is also a function by which one connection from an (ISO) layer is used to support more than one connection to the next higher layer.

A device for combining several channels to be carried by one line or fiber

MVL:

Multiple Virtual Line

MVS:

Multiple Virtual Storage: An IBM host operating system.

MWS:

Message Work Station

MX RECORD: 

Mail Exchange Record: DNS resource record type indicating which host can handle e-mail for a particular domain.

MY DOCUMENTS:

A folder that provides a convenient place to store documents, graphics, or other files for quick access: When a user saves a file in a program such as WordPad or Paint, the file is automatically saved in My Documents, unless a different folder is specified.