QoS (quality of
service): the capability of a network to provide better service to selected
network traffic
over various
technologies
RAM (random access
memory): chips
capable of storing and later dumping data in preparation for other uses
RARP (reverse address
resolution protocol): protocol used to resolve an IP address from a given hardware
address (e.g., an
Ethernet address)
RAS (remote access
service): allows users to access the network through dial-up modem
connections
Receiver: destination of the
message or data
Recovery routine: enables a computer to
resume operation after encountering a problem, such as a power
outage or program error
Remote login: allows a user at one
computer to interact with another, as if the user’s computer is directly
attached to the remote
computer
Removable storage: a way to store
information on disks that can be removed and used on different systems;
most removable drives
(also known as floppy drives) use a hard 3.5 inch disk
Repeaters: regenerate and reshape
digital pulses and allow a signal to be transmitted further than a single
circuit can achieve
RIP (routing information
protocol): used by routers connecting LANs to exchange routing table
information
to determine the best
path through the network at any point in time
ROM (read-only memory): chips that store data
that needs to be maintained constantly
Routers: basic piece of network
hardware necessary to connect one network to another; makes decisions about
packet forwarding based
on IP address information in the packet; directs traffic between network
segments
RTMP (routing table
maintenance protocol): a communication protocol used by AppleTalk to ensure
that all routers on the
network have consistent routing information
SAPs (service access
points): represent
internal software addresses in the sending or receiving computer
SAR (segmentation and
reassembly): the process used to fragment and rebuild packets that allows them
to be transported across
asynchronous transfer mode (ATM)
SDH (synchronous digital
hierarchy): international counterpart of SONET
SDRAM (synchronous
dynamic random access memory): version of DRAM that allows for
increased speed
SEAL (simple and
efficient AAL): method of relaying ATM (asynchronous transfer mode) cells between
ATM Layer and a higher
layer
Section layer: layer of the OSI
physical layer that creates frames, monitors the conditions of the transmission
between the SONET
equipment, and converts optical signals to and from electrical signals
Security routines: protect data and
applications from unauthorized use, execution, or change
Semaphores: messages sent when a
file is opened that prevent other users from opening the same file at
the same time and
compromising the integrity of the data
Serial port: handles data one bit at
a time traveling sequentially across a single line from one device to the next
Server: a computer that provides
services to the other workstations
Simplex transmission: the information always
flows from the transmitter to one or more receivers with no
provision for a return
signal; like radio and TV broadcasts
SMLI (stateful
multi-layer inspection): similar to application gateways; however, no proxy is used
between the network and
the Internet
SMLIS (stateful multilayer
inspection servers): sophisticated firewalls that inspect each frame for suspicious
communications
SMTP (simple mail
transfer protocol): electronic mail service that allows a user to send or receive
messages
SNA (systems network
architecture): IBM’s mainframe network standards
SNMP (simple network
management protocol): application layer protocol in the TCP/IP family; provides
remote network
management capabilities to a network administrator; implemented with
centralized management
stations that collect network
information from agents throughout the network; can also send commands
to the agents to alter
the configuration or status of remote devices
SOCKS (an abbreviation
of SOCKetS): protocol for handling TCP though a proxy server; library of
software
added to an individual
application for secure communication through the firewall
SOCKS servers: specialized servers for
prearranged communications through a firewall
Software: instructions that tell
computers how and under what circumstances to function
SONET (synchronous
optical network): standardized hierarchy of digital transmission rates for North
American and ITU-T rates
SQL (structured query
language): computer language used to create, retrieve, update, and delete
data
from relational database
and/or object-relational database management systems; pronounced “sequel”
StartTopology: physical topology where
all devices attach to a common wiring point; alternative to
Bus topology
SRAM (static random
access memory): holds information until the electricity is turned off; faster and
more expensive than
DRAM; most computer manufacturers use SRAM for caching
STDM (statistical
time-division multiplexing): a method for transmitting several types of data
simultaneously
across a single
transmission cable or line
STM-1 (synchronous
transport module, level 1): the basic rate of transmission of the SDH ITU-T
fiber
optic network
transmission standard
Storage devices: means of storing data in
the computer system for later retrieval and use
STS-1 (synchronous
transport signal, level 1): base signal in SONET (synchronous optical
network)
Subnetting: logical segmentation of
the network into smaller, more manageable parts
SVCs (switched virtual
circuits): use a real, shared circuit path in the service provider’s backbone
for the
duration of the call or
connection only
Switched lines: another name for dial-up
or circuit switched lines
Switches: intelligent devices that
look at the destination MAC address in a frame and decide whether it
should be forwarded or
filtered; work like bridges with more ports; make decisions in hardware rather
than
software for a faster
response
Switching: preferred method of
interconnecting devices in the LAN environment; provides greater throughput
at lesser cost than
traditional routers
T1: leased-line services
from telephone companies that provide the most popular high-speed connectivity;
E1
is the European version,
J1 the Japanese version
Tbps: Trillions of bits per
second
TCP/IP (transmission
control protocol/Internet protocol): dominant protocol suite used in networking
TCP (transport control
protocol): connection-oriented, reliable protocol that has end-to-end
responsibility
for making sure that
information arrives without errors and in the correct order
TDM (time-division
multiplexing): used in the T1 frame format; different channels are multiplexed by
being assigned their own
individual time slots
Threads: individual processes
within a single application
Three-layer Network
Model: shows
network communications as a set of three conversations
Transmitter: source that generates
the message or data
Transport layer: layer that is
responsible for delivering information in sequence and to the correct end-user
Trap: SNMP protocol function
used by the agent in a managed device to report important events or alarms
Topology: the physical (how the
wires are laid out) and/or logical (how the wires work) arrangement of the
devices on the network
UART (universal
asynchronous receiver/transmitter): a computer component that handles asynchronous
serial communication;
pronounced U-art
UDP (user datagram
protocol): connectionless, unreliable protocol that exchanges datagrams
without
acknowledgments or
guaranteed delivery; requires error processing and retransmission by other
protocols
USB (universal serial
bus) port: designed to replace the RS-232 connection with one that can handle
up
to 127 devices; comes in
15 Mbps or 12 Mbps speed
USENET (USEr NETwork): Internet service that
enables open forum discussions with people all over the
world through newsgroups
User interface: how you interact with
the computer
Utility routines: diagnostic, tracing,
monitoring, and resource housekeeping functions
UTP (unshielded
twisted-pair): the most common cable used in computer networking
VBR (variable bit rate):
transmissions
that are not time sensitive - the receiving computer can reconstruct the
information regardless
of how quickly or in what order the parts are received; also called “bursty”
transmission
VCI (virtual channel
identifier): identifies the virtual channel between ATM switch nodes
VoIP (Voice over
Internet Protocol): routing of voice conversations over the Internet or through any
other IP-based network;
also called telephone, broadband phone
Volatile memory: chips that lose whatever
information they are holding if power is interrupted
VPI (virtual path
identifier): traces the virtual path, from endpoint-to-endpoint, through the
ATM network
WDM (wavelength-division
multiplexing): when two or more different wavelengths of light each carrying
information are
multiplexed together on a fiber link, and demultiplexed at the receiving end to
recapture
the individual
information carried by each wavelength used
WAN (wide area network):
geographically
dispersed network of computers
WC3 (World Wide Web
Consortium): user and developer forum dedicated to developing interoperable
Web technologies
(specifications, guidelines, software, and tools)
Wi-Fi: describes the underlying
technology of wireless local area networks (WLAN) based on IEEE specifications;
originally developed for
mobile computing devices in LANs, but is now used for more services, including
Internet and VoIP phone
access
Wireless: telecommunications in
which electromagnetic waves (rather than some form of wire) carry the signal
over part or all of the
communication path
Word size: number of bits that a processor
can manipulate at a time
WPAN (wireless personal
area networks): wireless network for interconnecting devices centered around
an individual person's
workspace; typically limited to a 10 meter range
WLAN (wireless local
area network): computer network used for wireless communications among computer
devices (including
telephones and PDAs); also known as LAWN (local area wireless network)
WWW (World Wide Web): server-based application
that organizes information using hypermedia
xDSL (digital subscriber
line): technologies
that provide digital data transmission over the wires of a local
telephone network
XML (extensible markup
language): W3C (World Wide Web consortium)-recommended general-purpose
markup language that
supports a wide variety of applications