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Term Main definition
(1) See media access control. (2) Abbreviation for moves, adds, and changes.
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MAC Media access control

A sublayer of the OSI Data Link layer (Layer 2) that controls the way multiple devices use the same media channel. It controls which devices can transmit and when they can transmit. For most network architectures, each device has a unique address that is sometimes referred to as the MAC address.

Network-adapter cards such as Ethernet, Token Ring, and FDDI cards are assigned addresses when they are built. A MAC address is 48 bits represented by six sections of two hexadecimal digits. No two cards have the same MAC address. The IEEE helps to achieve the unique addresses by assigning the first half to manufacturers so that no two manufacturers have the same first three bytes in their MAC address. The MAC address is also called the hardware address.

See also media access control (MAC) address.

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A major bend in an optical fiber with a radius small enough to change the angle of incidence and allow light to pass through the interface between the core and the cladding rather than reflect off it. Macrobends can cause signal attenuation or loss by allowing light to leave the optical fiber core.
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Macrobending loss
Optical power loss due to large bends in the fiber.
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Main cross-connect
A cross-connect for first-level backbone cables, entrance cables, and equipment cables. The main cross-connect is at the top level of the premises cabling tree.
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Main distribution frame (MDF)
A wiring arrangement that connects the telephone lines coming from outside on one side and the internal lines on the other. The MDF may be a central connection point for data communications equipment in addition to voice communications. An MDF may also carry protective devices or function as a central testing point.
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Main Feeder

Main feeder connecting BTS / Node B to the antenna / MHA.

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Mains Lead

Most commonly an IEC C13 Female to UK Mains plug. However there can be many variations so check this with the customer.
(see Kettle lead)

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Manchester coding
A method of encoding a LAN in which each bit time that represents a data bit has a transition in the middle of the bit time. Manchester coding is used with 10Mbps Ethernet (10Base-2, 10Base-5, 10Base-F, and 10Base-T) LANs.
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Mandrel wrap
A device used to remove high-order modes caused by overfilling in a length of optical fiber for insertion loss measurements.
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The allowance for attenuation in addition to that explicitly accounted for in system design.
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Mass splicing
The concurrent and simultaneous splicing of multiple fibers at one time. Currently mass splicing is done on ribbon cable, and the standard seems to be ribbon cable with 12 fibers. Special splice protectors are made for this purpose, as well as special equipment for splicing.
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FULL Master - For a direct line from the telephone company and not via the office telephone exchange, PABX

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Material dispersion
A pulse dispersion that results from each wavelength traveling at a speed different from other wavelengths through an optical fiber. See also chromatic dispersion.
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MAU Medium attachment unit

When referring to Ethernet LANs, the transceiver in Ethernet networks.

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