- MAC (Media Access Control) layer A sub-layer of the Data Link Layer (Level Two) of the ISO OSI Model responsible for media control.
- MAN (Metropolitan Area Network) A high speed network designed to link together sites in a metropolitan or campus area. The IEEE has defined its 802.6 standard for MANs based on the Distributed Queue Dual Bus technology.
- MAP (Manufacturing Automation Protocol) An ISO OSI protocol stack that is defined as a functional profile. Originally developed by General Motors for use in factory floor manufacturing environments it is based around the IEEE 802.4 Token Bus LAN technology.
- MAPI (Messaging Application Programming Interface) Microsoft's standard for the applications interface to e-mail. See also VIM.
- Master station A device that controls/polls the nodes in multipoint circuits or, in point-to-point circuits, the unit that controls the slave station. In LAN terms, the device on a token passing ring that enables recovery from error conditions, such as lost, busy or duplicate tokens, usually by generating a new token. Servers are sometimes called master stations.
- Matrix switching A form of data switching at the heart of ATM, enabling the appropriate of bandwidth to be available end-to-end for the duration of the session without contention.
- MAU (Medium Attachment Unit) A transceiver (transmitter/receiver) comprising hardware circuitry that provides the correct electrical or optical connection between the computer and IEEE 802.3 LAN media. Since MAUs typically support only one type of network medium, a choice of MAUs is available to support different media. It detects carrier and collision activity, passing the information to the Computer. It can be a standalone unit or incorporated in a circuit board inside the computer,
- MC message code
- MDI medium dependent interface
- Media Access Control driver A LAN device driver that works directly with the network adapter cards, acting as an intermediary between the transport driver and the hardware.
- Medium The physical method or equipment used for transmission, from a tangible fiber optic or copper cable to a satellite link. Alternatively, a little old lady in a shawl used as a last resort to retrieve lost data.
- Medium Interface Controller (MIC) An hermaphrodite connector on IBM patch parels specified in 802.5.
- Member server A server in a domain that keeps and uses a copy of the domain's user accounts database but does rot validate logon requests.
- Metadata is information about data (a ressource, an object,...), be it physical or digital. Provides, e.g., a description of the content, format, or utility of the data (ressource, object,...)
- MIB (Management Information Base) The set of variables or database that a gateway running CMOT, SNMP, or CMIP network management protocols maintains. It defines variables needed by the SNMP protocol to monitor and control components in a network. Managers fetch or store into these variables. MIB-II refers to an extended SNMP management database that contains variables not shared by both CMOT and SNMP. The CMIP and SNMP MIB formats differ in structure and complexity.
- Microchannel A proprietary bus developed by IBM for its PS/2 computer family's internal expansion cards. It offers improved performance over ISA-based machines like the IBM PC/AT.
- Microwave Wireless transmission at very high frequency to deliver telecommunications services, including TV distribution, between two points. It is dependent on line of sight.
- MII media independent interface
- Milnet (Military Network) Originally part of Arpanet, Milnet was partitioned in 1984 to make it possible for military installations to have a reliable network service while the Arpanet continued to be used for research. Under normal circumstances, Milnet is part of the Internet.
- Monolithic driver A network device driver that acts as network adapter card driver and transport protocol driver combined.
- MMF multimode fiber
- MMS stands for Manufacturing Message Specification. MMS is an International Standard ISO/IEC 9506. The latest version has the date 2000 (ISO/IEC 9506:2000)
- MTBF (Mean Time Between Failures) A term describing the reliability of equipment established by testing kit to its limits and promoting the MTBF as a selling point. As most users know, however, laboratory and operational environments have little in common.
- MNP (Microcom Networking Protocol) A series of protocols designed by Microcom to support error control and data compression for asynchronous modem transmission.
- Modem A device named from an amalgam of the words modulator and demodulator. A modem will modulate an outgoing binary bit stream or to an analog carrier, and demodulate an incoming binary bit stream from an analog carrier.
- Modem Approvals Group Established in January 1993 to raise awareness of the UK law against connecting unapproved devices to the PSTN, this group demands a level playing field in the modem market with better law enforcement or more open standards.
- Modem eliminator A device that can replace a modem in some instances when the distance to be covered is short. It takes the power it needs to operate from the transmission line.
- MP message page
- MSAU (Multi-Station Access Unit) A wiring concentrator on a Token Ring network that allows devices, typically eight to 12 Token Ring stations, to be connected to the ring. Relays in the MAU ensure the integrity of the network when devices are attached or removed. A Managed Multi-Port/Multi-Station Access Unit has built-in network management support.
- MS-Net Microsoft DOS-based networking system software product (Microsoft Network).
- Multi-drop A transmission circuit with multiple terminals and peripherals. Could also be described as branches off a bus.
- Multi-point A link that connects more than two points. Interchangeable with multi-drop.
- Multi-point connection A single channel or circuit interconnecting devices in different locations. This usually means using polling techniques with each terminal[terminal a unique address. Also know as a multi-drop line.
- Multi-cast bit A bit found in the Ethernet addressing scheme that indicates that the message is to be sent to all stations.
- Multi-cast message A message that is intended for a set of stations on a network.
- Multimedia Generic description of the generation and transfer of voice/data/video traffic between users. Applications to exploit multimedia to the full are emerging in the wake of advanced switching techniques and develop merits in desktop and server processing architectures. It may be essential to a physically separated group that communicates as if it was physically networked.
- Multi-Port Repeater An Ethernet wiring center that allows multiple devices to be attached at one point on an Ethernet. A Managed Multi-Port Repeater has network management capabilities.
- Multiplexer A device that can send several signals over a single line. They are then separated by a similar device at the other end of the link. This can be done in a variety of ways: time division multiplexing, frequency division multiplexing and statistical multiplexing. Multiplexers are also becoming increasingly efficient in terms of data compression, error correction, transmission speed and multi-drop capabilities.
- Multi-tasking The concurrent execution of two or more tasks or the concurrent use of a single program that can carry out many functions.