Metropolitan Area Network (MAN)
A network that interconnects users with computer
resources in a geographic area or region larger than
that covered by even a large local area network
(LAN) but smaller than the area covered by a wide
area network (WAN). The term is applied to the
interconnection of networks in a city into a single
larger network (which may then also offer effi cient
connection to a wide area network). It is also used
to mean the interconnection of several local area
networks by bridging them with backbone lines.
The latter usage is also sometimes referred to as
a campus network.
MIB (Management Information Base)
A collection of objects (database) that can be
accessed via a network management protocol.
See SNMP and RFC 1066.
MIB-II (Management Information Base, Version 2)
The revised object defi nitions for Internet standard
network management. Objects are defi ned using a
subset of the Abstract Syntax Notation One (ASN.1).
See SNMP and RFC 1213.
MPEG (Moving Pictures Experts Group)
An ISO (International Standards Organization) group
that sets standards for compressing and storing
video, audio, and animation in digital form.
MPEG-1
Provides a video resolution of 352 by 240 at 30
frames per second (fps). This was designed to work
at 1.2 Mbps. Is meant for medium-bandwidth usage.
MPEG-2
Offers resolutions of 720 x 480 and 1280 x 720 at
60 fps, with data rates of between 1.2 and 15 Mbps,
with full CD-quality audio. Is meant for high-band-
width/broadband usage.This works for all the major
TV standards, including NTSC and even HDTV.
MPEG-4
Designed specially for low-bandwidth (less than
1.5 Mbps bitrate) video/audio encoding purposes.
Delivers video at comparable quality to MPEG1 at a
much lower bit rate. Also supports a wide variety of
elements that can be transmitted separately and
combined to form the video frame, such as a talking
head in one stream and the background in another.
Allows manipulation of objects within the video stream
(addition, subtraction, object manipulation, etc.).
MTU (Maximum Transmission Device)
The largest possible device of data that can be
transmitted between a source and a destination.
Note that a distinction must be made between the
MTU for a physical medium (segment), a path, and
for protocols. For example, Ethernet has an MTU of
1500 bytes, while FDDI has an MTU of 4470 bytes;
ATM uses an MTU of 9180 bytes. AppleTalk has an
MTU of 600 bytes, while IP has an MTU limit of 65
535 bytes (less the header). The MTU between two
endstations is always the minimum of the MTUs of
all the media (segments) separating the endstations.
See RFC 1191 for a discussion of determining the
MTU of an internetwork between two endpoints.
Multicast
Communication between a single sender and
multiple receivers on a network. Streaming content
can be sent multicast from one server to many
users. Compare with unicast.
Multicast Address
An address that refers to multiple network devices.
Synonymous with group address.
Multimode Fiber (MMF)
Optical fi ber cable with a relatively wide core
(62.5 µm or 50 µm) that allows multiple rays of light
to follow different paths through the core.Termination
is easier and cheaper, driven by optical diodes,
good for short distances typically up to 2 km, more
forgiving of termination errors.
Netmask
A bit mask used to select bits from an Internet
address for subnet addressing. The mask is 32 bits
long and selects the network portion of the Internet
address and one or more bits of the local portion.
This is also sometimes referred to as the address
mask or subnet mask.
Network
A group of stations (computers, telephones, or other
devices) connected by communications facilities for
exchanging information. Connection can be perma-
nent, via cable, or temporary, through telephone or
other communications links. The transmission
medium can be physical (i.e. fi ber optic cable) or
wireless (i.e. satellite).
Network Address
The hostid 0 of an IP address is reserved;
an IP address with the hostid zero is used to refer
to the network itself.
Glossary
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