background image
Glossary
719
lines. This is achieved by converting digital signals at
the source to analog for transmission and reconverting
the analog signals back into digital form at the destina-
tion. See also: modulation and demodulation.
modem eliminator
A mechanism that makes possi-
ble a connection between two DTE devices without
modems by simulating the commands and physical
signaling required.
modulation
The process of modifying some char-
acteristic of an electrical signal, such as amplitude
(AM) or frequency (FM), in order to represent digital
or analog information. See also: AM.
MOSPF
Multicast OSPF: An extension of the OSPF
unicast protocol that enables IP multicast routing
within the domain. See also: OSPF.
MPOA
Multiprotocol over ATM: An effort by the
ATM Forum to standardize 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.
MTU
maximum transmission unit: The largest
packet size, measured in bytes, that an interface can
handle.
multicast
Broadly, any communication between a
single sender and multiple receivers. Unlike broadcast
messages, which are sent to all addresses on a net-
work, multicast messages are sent to a defined subset
of the network addresses; this subset has a group mul-
ticast address, which is specified in the packet's desti-
nation address field. See also: broadcast, directed
broadcast.
multicast address
A single address that points to
more than one device on the network by specifying a
special non-existent MAC address specified in that
particular multicast protocol. Identical to group
address. See also: multicast.
multicast send VCC
A two-directional point-to-
point virtual control connection (VCC) arranged by
an LEC to a BUS, it is one of the three types of infor-
mational link specified by phase 1 LANE. See also:
control distribute VCC
and control direct VCC.
multilayer switch
A highly specialized, high-speed,
hardware-based type of LAN router, the device filters
and forwards packets based on their Layer 2 MAC
addresses and Layer 3 network addresses. It's possible
that even Layer 4 can be read. Sometimes called a
Layer 3 switch. See also: LAN switch.
multimeters
Hardware used measure voltage, resis-
tance, and current. They work with electrical-based
cabling and can be used to test for physical connectivity.
multiplexing
The process of converting several log-
ical signals into a single physical signal for transmis-
sion across one physical channel. Contrast with:
demultiplexing.
NAK
negative acknowledgment: A response sent
from a receiver, telling the sender that the information
was not received or contained errors. Compare with:
acknowledgment.
NAT
Network Address Translation: An algorithm
instrumental in minimizing the requirement for glo-
bally unique IP addresses, permitting an organization
whose addresses are not all globally unique to connect
to the Internet, regardless, by translating those
addresses into globally routable address space.
NBP
Name Binding Protocol: In AppleTalk, the
transport-level protocol that interprets a socket cli-
ent's name, entered as a character string, into the cor-
responding DDP address. NBP gives AppleTalk
protocols the capacity to discern user-defined zones
and names of mechanisms by showing and keeping
translation tables that map names to their correspond-
ing socket addresses.
neighboring routers
Two routers in OSPF that
have interfaces to a common network. On networks
with multi-access, these neighboring routers are
dynamically discovered using the Hello protocol of
OSPF.
NetBEUI
NetBIOS Extended User Interface: An
improved version of the NetBIOS protocol used in a
number of network operating systems including LAN
Manager, Windows NT, LAN Server, and Windows
for Workgroups, implementing the OSI LLC2 proto-
col. NetBEUI formalizes the transport frame not stan-
dardized in NetBIOS and adds more functions. See
also: OSI.
Copyright ©2000 SYBEX , Inc., Alameda, CA
www.sybex.com