ICANN (Internet
Corporation for Assigned Names and Numbers): non-profit corporation created to
oversee Internet-related
tasks previously performed for the U.S. Government by other organizations;
tasks
include managing the
assignment of domain names and IP addresses, and introducing new generic
top-level
domains; pronounced “I
can”
ICMP (Internet control
protocol message protocol): network layer protocol provided with TCP/IP;
used
to report errors and
provide other information relevant to IP packet processing
IEEE (Institute of Electronic
consensus standards for
network wiring and other technologies; pronounced “eye-triple-E”
IGMP (Internet group
management protocol): a communications protocol used to manage the membership
of IP multicast groups
IGP (interior gateway
protocol): set of routing protocols used within an autonomous system
IGRP (interior gateway
routing protocol): developed by Cisco to provide a robust protocol for rerouting
within an autonomous
system (AS); a type of IGP
ILECs (incumbent local
exchange carriers): a telephone company providing local service when the
Telecommunications Act
of 1996 was enacted (see CLEC)
ILP (initial loader
program): reads an existing file containing database records; also called a
boot-loader
Input/output management
routines: provide orderly control and flow of information between a
computer’s
main memory and attached
peripheral devices
Interface: point in the system
where the rules, control codes, formats, and information direction (as dictated
by the protocol) are
implemented
Interior protocols: routing protocol used
within/interior to an independent/ autonomous system
Internet layer: part of the TCP/IP model
that performs the same function as the network layer of the OSI model
Internetworking: connecting one network
to another network
Interprocess
communication: allows programs to share information dynamically, whether running
locally
or remotely
I/O (Input/output
devices): hardware used to enter and retrieve data from the system
IP (internet protocol): network layer protocol
provided with TCP/IP; connectionless, unreliable protocol that
provides features for
addressing, type or service specification, fragmentation and reassembly, and
security
IP address (internet
protocol address): logical address assigned to every workstation, server, printer,
and
router on any
interconnected network
IPX/SPX (Internetwork
packet exchange/sequenced packet exchange): a networking protocol used
by the Novell NetWare
operating systems; it is a datagram protocol used for connectionless communications
IRC (Internet relay
chat): allows
groups to communicate interactively via keyboard and screen display
ISDN (Integrated
Services Digital Network): a circuit-switched telephone network system designed to
allow digital
transmission of voice and data over ordinary copper telephone wires
ISDN PRI: switched-line service
from telephone companies that operates over T1 (or E1/J1) facilities
IS-IS (intermediate
system-to-intermediate system): an interior gateway protocol (IGP) intended for
use within an administrative
domain or network
ISPs (Internet service
providers): businesses or organizations that provide consumers with access to
the
Internet and related
services
IT (information
technology): broad term that can refer to anything from mainframes to PDAs; any
technology
that moves information
(voice, video, or data)
ITU-T (ITU
Telecommunication Standardization Sector): coordinates standards for
telecommunications
on behalf of the International
Telecommunication Union (ITU)
IXC (interexchange
carrier): a telephone company that provides connections between local
exchanges in
different geographic
areas
Jitter: distortion in a digital
signal caused by a shift in timing pulses; can cause data interpretation errors
JPEG (Joint
Photographics Experts Group): a lossy compression technique for color images;
pronounced
jay-peg (see Lossy)
Kbps (thousands of bits
per second): a measure of data transfer speed
kHz (kilohertz): a unit of measurement of
frequency, also known as cycles per second; e.g., one kilohertz
equals 1,000 Hz, or
cycles per second
LAN (local area
network): network that operates within a small geographic area, usually
within a building,
office, or department
LAPB (link access protocol,
balanced): a data link protocol in the X.25 stack
LATAs (local access and
transport areas): In the US, refers to a geographic region assigned to one or
more telephone companies
for providing communication services
Layer 2 switches: interpret and make
switching decisions on the LAN hardware adapter address contained
in the data link header
of MAC frames; forward frames only to the destination hardware address
contained in
the frame
LCI (logical channel
identifier): used to define frequencies in use on M/A-COM EDACS (Enhanced
Digital
Access Communications
System) systems and LTR (logic trunked radio) systems; more commonly known as
logical
channel number (see
LCN); also known as virtual channel;
LCN (logical channel
number): used
to define frequencies in use on M/A-COM EDACS (Enhanced Digital
Access Communications
System) systems and LTR (logic trunked radio) systems; also known as the
logical
channel identifier (see
LCI); also known as virtual channel
LE (local exchange): a regulatory term in
telecommunications for local telephone company
Leased lines: another name for private
lines, dedicated lines, or permanent circuits
LEC (local exchange
carrier): a public telephone company in the US
LGN (logical channel
group number): together with the LCN (in the X.25 packet header), identifies the
actual logical channel
number of the DTE-DCE link; a 4-bit field representing a number between 0 and
15
Line layer: layer of the OSI
physical layer that is responsible for synchronizing and multiplexing multiple
streams of data into one
SONET stream within SONET frames; also monitors and administers SONET
multiplexers
LLC (logical link
control): standard interface allowing any combination of MAC techniques and
physical
media to be used
simultaneously in the same workstations; shields higher layer protocols from
the peculiarities
of the physical medium
Logical segmentation
devices: allow
network designers to maintain separate networks (often for security
reasons) that can still
communicate with one another
Lossy: data compression method
where compressing and then decompressing retrieves data that may well be
different from the
original, but is "close enough" to be useful in some way
LU (logical unit): identifies an end-user
in IBM's Systems Network Architecture (SNA)
MAC (media access
control) address: unique 6-byte address associated with and coded into each network
interface card (NIC);
address assignment is controlled by the IEEE
MAN (metropolitan area
network): connects sites in and around a large city
MB (megabyte): unit of information or
computer storage equal to either exactly one million bytes or, in some
cases, 1,048,567 bytes,
or more rarely, 1,024,000 bytes; not to be confused with Mb, which stands for
megabits
Mbps (megabits per
second): a
unit of information storage; not to be confused with MB or megabytes
Medium: transmission, or system
that carries the message or data
MAU (medium attachment
unit): converts
signals on an Ethernet cable to and from AUI signals.
Memory: desk space of the
computer system; microchips located on the motherboard that hold data and
instructions for the CPU
(central processing unit)
Memory management: allocates memory to
separate tasks and protects data from corruption
Menu: used in some DOS shells
and early versions of Windows; an improvement on the command line but
cumbersome when a task
requires the submenu of a submenu of a submenu of a menu item
Message: information content to
be shared
MHz (megahertz): one hertz is one cycle
per second; a megahertz is equal to one million cycles per second
MIB (management
information base): a type of database used to manage the devices in a communications
network
MPEG (Motion Picture
Experts Group): digital video format identified by “.mpg” extension after the file
name; a working group of
ISO/IEC charged with the development of video and audio encoding standards;
pronounced
m-peg
MPLS (multiprotocol
label switching): an initiative that integrates Layer 2 information about network
links (bandwidth,
latency, utilization) into Layer 3 (IP) within a particular autonomous system
to simplify and
improve IP packet
exchange
Mpps (millions of
packets per second): a measurement of information sent per second
Multiplexing: process of putting
multiple signals on a wire simultaneously
Multiport repeaters: allow multiple devices
to be wired to a central location, share the same media, and
regenerate (repeat) the
signal; also referred to as active hubs
Multitasking routines: permit two or more
distinct tasks to be performed concurrently by the computer
Name resolution: process by which the
peer-to-peer name used on each conversational level is related to
other levels
NAP (network access
point): transitional
data communications facilities at which Network Service
Providers (NSPs) would
exchange traffic, in replacement of the publicly-financed NSFNet Internet
backbone;
now replaced by modern
IXPs
NAT (network address
translator): involves re-writing the source and/or destination addresses of IP
packets
as they pass through a
router or firewall; also called network masquerading, native address
translation, or
IP-masquerading
NetBIOS (network basic
input/output system): allows applications on separate computers to communicate
over a local area
network (LAN)
Network access layer: allows a computer to
exchange data with another computer over a common network
medium; part of the
TCP/IP model that performs the same functions as the data link and physical
layers
of the OSI model
Network address: part of an IP address
that is uniquely assigned by one of the ICANN-sanctioned agencies
Network design: how the various clients
and servers are arranged for purposes of connectivity, performance,
and security
NOS (network operating
system): optimizes
the client/server architecture; provides and supports network
services such as file
services, e-mail, Internet and intranet services, and applications
NIC (network interface
card): hardware
adapter that provides communication capabilities; responsible for
building, transmitting,
receiving, and decoding frames in a LAN environment; serves as the interface
between
the networked devices
and the connecting wires
NNTP (network news
transfer protocol): makes USENET possible; protocol for the distribution, inquiry,
retrieval, and posting
of news articles using a reliable stream-based transmission of news among the
ARPAInternet
community
Nonvolatile memory: chips that hold
information even when the system is turned off
NRZ-L (non-return to
zero level): form of digital encoding; negative voltage is used to represent a
binary
1, and a positive
voltage is used to represent a binary 0
NSP (network service
provider): a business or organization that sells bandwidth or network access
by
providing direct
backbone access to the Internet, and usually access to it’s network access
points (see NAP)
OC1 (optical carrier, level
1): a
fiber optic connection capable of transferring data at 51.85 Mbps
Operating environment: how the OS controls the
hardware and application programs
OS (operating system): interface between the
application (word processor, spreadsheet, etc.) and the computer
hardware
OSI (open systems
interconnection) model: developed to provide a view of the distinct functionalities
that are required to
implement each protocol layer; defines a complete range of functions that can
be achieved
with data communications
equipment
OSPF (open shortest path
first): a
link-state hierarchical interior gateway protocol (see IGP) for network
routing protocol
Packet filters: security method that
filter by IP address; not adequate security for a network
Packets: data structures that
collectively represent the transmission stream (headers and data); associated
with the network layer
when the communication protocol is connection-oriented
PAD (packet
assembler/disassembler): assembles X25 packets on the sending end for transmission
over
the X25 PSDN, or
disassembles X25 packets on the receiving end for onward transmission to the
local network
Parallel port: port where the bits
travel down parallel paths, arriving one byte at a time; can supply more
bytes of data per unit
time
Passive hubs: used in a LAN
environment; special form of repeater that allow multiple devices to be wired
into a central location
and share the same media; do not regenerate (repeat) the signal
Path layer: layer of the OSI
physical layer that is responsible for reliable end-to-end transport and
payload
delivery, including
automatic recovery from failure points
PBX (private branch
exchange): a telephone exchange that serves a particular business or office
PC (personal computer): a microcomputer whose
price, size, and capabilities make it useful for individuals
PCI (peripheral
component interconnect): a computer bus for attaching peripheral devices to a
computer motherboard
PCM (pulse code
modulation): process for converting from analog to digital
PDA (personal digital
assistant): hand-held computer with a touch screen
PDU (protocol data
unit): information
that is delivered as a unit among peer entities of a network; in layered
systems, a unit of data
that is specified in a protocol of a given layer
Phase: where in the wave cycle
the wave currently is; measured in degrees
Peer-to-peer networks: network in which each
computer is capable of functioning as a client and a server;
users on the network can
freely share resources on their computer or access shared resources on other
computers
Photonic layer: layer of the OSI
physical layer that specifies fiber cable with optical light sources and
receivers
Physical segmentation
devices: divide
collision domains to improve network performance
between two TCP/IP
network devices
POP (Post Office
Protocol): how clients access their mailboxes on the messaging server;
usually done in its
third version, POP3
POPs (points of
presence): an artificial demarcation point or interface point between
communications entities
POST (power-on
self-test): the pre-boot sequence for a computer, router, or printer
POTS (plain old
telephone service): standard telephone service, the basic form of residential and
small
business telephone
service
PRI (primary rate
interface): an integrated services digital network (ISDN) configuration,
usually intended
for large users (see also
BRI)
Process and application
layer: Part
of the TCP/IP model that performs the same functions as the application,
presentation, and
session layers of the OSI model
Processor: brain of the computer
system where calculations and decisions are made; also referred to as the CPU
Processor memory: referred to as the L1
(level 1), an interface between the processor and the cache
Protocol: set of rules used to
control the exchange of information that is understood by the transmitter and
receivers
Proxy server: sits between the network
router and the Internet; talks to the Internet on behalf of a network’s
resources, allowing real
network addresses to be hidden
PSDN (packet-switched
data network): a publicly available network supporting packet-switched data,
separate from PSTN
PSTN (public switched
telephone network): the network of the world’s public circuit-switched telephone
networks; in much the
same way the Internet is the network of the worlds’ public IP-based
packetswitched
networks
PU (physical unit): a value or magnitude
conventionally adopted as a unit or standard of physical measurements
(e.g., length, mass, and
time); identifies a network node that supports communication sessions between
logical units (LU) which
represent end users in IBM's SNA,
Pure play: newly developed business
built on advantages afforded by e-commerce
PVCs (permanent virtual
circuits): use a real, shared circuit in the service provider’s backbone