Glossary M, N, O

MAC address Media Access Control - an addressing system using a 48 bit (6 byte) address, allocated by the IEEE standards organisation. 48 bits equals 280 trillion unique addresses, there are no doubles.

MAN Metropolitan Area Network - Describes a network spanning a geographical area greater than a LAN (local area network) but less than a WAN (wide area network) e.g. the span of a city or a large campus. 

Managed Switch These types of switches contain one or more methods to modify the operation of the switch by users such as a GUI or web-based management systems. 

MDI Medium Dependent Interface see Auto-MDIX 

MDIX Medium Dependent Interface Crossover see Auto-MDIX 

Media Converter - A networking device that allows the connection of fibre optic cable systems to copper cabling installations or other dissimilar media types. 

Megabit One million bits (1,000,000 bits; Mb). A fast Ethernet link can carry 100Mb per second worth of information, a gigabit link carries 1000Mb.

MHz MegaHertz - Denotes a transmission rate of one million cycles per second. 

Micron See µ 

Mini-Zip Refers to a duplex cable that has been manufactured with two simplex cables with a sheath measuring 1.8mm in diameter each.  This is opposed to a Standard Zip cable whereby the diameter is 2.8mm for each simplex cable. 

Mil Tac A type of fibre optic cable that is suitable for Military Tactical applications and other environments where deployment and retrieval for reuse is required. 

MissingLink - A feature of some Allied Telesis Media Converters which allows accurate reporting to network management systems as well as allowing devices with redundant link capabilities to be inter-connected with these Media Converters, as a failure in one fibre link will be signalled to the network switch allowing the second link to be activated. 

MLD Snooping Multicast Listener Discovery Snooping - A protocol of IPv6, similar to IGMP Snooping which reduces the amount of multicast traffic on a network by sending streams only to interested recipients not all recipients. This results in a more efficient use of bandwidth. 

MMF - See Multi Mode Fibre 

Mode Conditioning Patch Cord/Cable Used with a 1000Base-LX transceiver to extend the range of Gigabit over OM1 (62.5/125 cable) from 250m to 550m.  For 10GbE applications, using a 10GBaseLRM transceiver you can achieve distances up to 220m with OM1 and OM2 cable. 

MPO Multi-Fibre Push On Connector. A 12 or 24 fibre connector. 

MTP©MPO Multi-Fibre Termination Push On Connector. A high performance MPO connector manufactured by US Conec. These can contain either 12 or 24 fibres in a compact connector providing savings in rack space. 

Multicast The 802.3 Ethernet standard allows information to be sent  to multiple devices on a network as multicast packets. The information can be picked up anywhere in the network.

Multi Mode Fibre Or MM fibre is a type of fibre used for networking over small distances with a data range of between 10 Mbit/s up to 10 Gbit/s up to 600m. 

NEBS Network Equipment Building Systems - A series of safety and conformance standards applied to telecommunications equipment in the USA. A feature of some Allied Telesis© products. 

Network Class Categorisation of a networks subnet mask; determining what portion of the IP address is the network number and what portion is the host address.

                              Class A: 1 byte ( 8 bits) network number, 3 bytes (24 bits) host address.

                              Class B: 2 bytes (16 bits) network number, 2 bytes (16 bits) host address.

                              Class C: 3 Bytes (24 bits) network number, 1 byte (8 bits) host address.

Small office networks mostly use class C.

NIC Network Interface Card - Also known as a Network or LAN adapter is a piece of computer hardware that allows a computer to connect to a network. 

Nm Nanometre - A unit of length denoting one billionth of a metre. 

OCA  Open Control Architecture - A system control and monitoring interoperability architecture, designed to simplify the design and intergration of professional media networks.

OSI model A standardised model for network protocols published by the international Organization for Standardisation ISO( The OSI model defines seven layers, defining the physical form of electrical data (layer 1) up to the network service application that uses he network (layer 7. MAC addressing is defined in layer 2; IP addressing is layer 3.

OSPF Open Shortest Path First - A routing protocol that allows routers to negotiate fast convergence of paths through a network. It allows load balancing across links, path configuration across multiple technologies and high performance routing across large infrastructures.

OM1/OM2/OM3/OM4/OM5 Different Multimode fibre standards - see FAQ here for more information

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