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56K
The term 56K refers to the latest generation of dial-up modems
that allow for communication between personal computers and
the Internet. 56K modems are capable of a theoretical maximum
of 57,600 or 56 Kbps. It is currently the highest available
connection speed through a standard dial-up modem. The newest
international standard for 56K data communications is now
known as v.92.
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A
ADSL
Asymmetric Digital Subscriber Line – ADSL is a transport
that allows faster flow of information (data, voice and video)
downstream than upstream. This is best suited for some applications,
such as using the Internet, where you typically need to receive
more data than you send. Other DSL applications - a corporate
data network, for example - require symmetric service, where
data are sent at the same rate in both directions.
ADSL Lite
This is a lower data-rate version of Asymmetric Digital Subscriber
Line (ADSL) technology.
Analog Communications
This is the method of voice transmission used in today's
telephone system. This method converts voice to electrical
signals and amplifies them so that the voice can be sent
over long distances. Using analog for data transmission is
at the bottom of the telecommunications bandwidth food chain.
Asymmetrical
This means an offering of different data rates in the upstream
and downstream directions—where upstream is the direction
from the end user to the network, and downstream is the
direction from the network to the user.
ATM
Asynchronous Transfer Mode - ATM, in this respect, means
a connection oriented, packet-like switching technology
that utilizes virtual channels instead of dedicated circuits
to carry data in fixed length (1 cell=53 bytes) over a
broadband network.
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B
Bandwidth
Bandwidth is the information-carrying capacity of a channel.
Expressed in hertz (e.g., kHz or MHz) for analog transmission
media and in bits-per-second (e.g., Kbps, Mbps) for digital
transmission media. It can also mean the width of a channel's
passband (e.g., the bandwidth of a channel with a 300 to
3400 Hz passband is 3100 Hz, or 3.1 kHz).
Bridge Unit
This connects one Local Area Network (LAN) to another that
uses the same protocol, (for example, Ethernet or Token
Ring. The bridge unit examines each message on a LAN 'passing'
those known to be within the same LAN and forwarding those
known to be on the other interconnected LAN(s).
Broadband
Broadband refers to high-speed Internet connections through
cable modems or DSL for example where the connection is ‘always
on’ until the computer is turned off.
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C
Cable Modem
A device that attaches between a PC and an analog-cable TV
and that uses your cable television line to transfer data
and provide you with high-speed Internet connection.
CAP
Carrier-less Amplitude/Phase (CAP) modulation—incoming
data modulates a single carrier that is then transmitted
down a telephone line. The carrier is suppressed before transmission
(it contains no information and can be reconstructed at the
receiver)—hence the term 'carrier-less.'
CDSL
Consumer Digital Subscriber Line - is a version of Digital
Subscriber Line (DSL) service, trademarked by Rockwell
Corporation, that is somewhat slower than Asymmetric DSL
(ADSL) —up to 1 Mbps downstream, probably less upstream—and
has the advantage that a splitter does not need to be installed
at the user's end. Rockwell no longer provides information
about CDSL at its Web site and does not appear to be marketing
it.
Channel
A channel is a transmission path between two points. The
term 'channel' usually refers to a one-way path, but when
paths in the two directions of transmission are associated—the
term 'channel' can also refer to this two-way path.
CPE
Customer-Premises Equipment— any equipment provided
by the customer on their own premises.
Customer Self-Install (CSI)
Customer Self-Install uses customer-installed, low-pass micro-filters
for each line analog device, (typically telephones, fax
machines, etc.), to filter out any DSL signal noise from
your voice service—allowing both voice and data to
share common inside wiring.
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D
Data
Data is a formal representation of any raw material from
which information is constructed through processing or
interpretation.
DHCP
Dynamic Host Configuration Protocol—DHCP allows a network
administrator to supervise and distribute IP addresses from
a central point and automatically sends a new address when
a computer is plugged into a different place in the network.
DMT
Discrete Multi-Tone (DMT), multi-carrier modulation uses
256 QAM modulation tones simultaneously to create the ADSL
signal. DMT is the basis of ANSI standard T1.413 and has
the support of other world standards' bodies.
Dial-up Connection
A connection to a remote computer made using a modem and
a regular voice telephone line. The top data transfer speed
for dial-up modems is 56 Kbps.
DNS
Domain Name Service - is the network information service
provided by the Internet for TCP/IP networks. Used to determine
the IP address of a computer on the Internet from its domain
name.
Domain Name
A text name that identifies an individual machine and the
domain it belongs to. Domain names generally indicate the
name of the organization or type of service the name belongs
to. Domain names are hierarchical, including the individual
computer name, the organization name, and the type of domain
(.edu, com, .net, etc.)
Downstream
Downstream refers to the data flow from the Internet or a
LAN to your computer (data you receive). A typical user
requires much higher bandwidth Downstream (to download
web pages or files from a LAN) than Upstream. DSL allows
you to download large music or video files in lightning
fast speeds compared to dial-up.
DSL
Digital subscriber line – is the technology currently
used to transmit data at much higher speeds than traditional,
analog technology. This technology can also allow you to
make a phone call while transmitting data (while using the
Internet, for example) on the same line. There are several
different types of DSL technology, offering speeds from 15
to 50 times faster than today's analog modems.
DSL Gateway
A DSL Gateway is made up of DSL network equipment, housed
in specialized buildings, that enable residential and business
customers to receive DSL Internet service who previously
were unable to receive the service. They act as miniature
central offices that are able to deliver DSL Internet service
beyond the standard 14,000-foot limit of a traditional
central office.
DSLAM
Digital Subscriber Line Access Multiplexer— is a device
that takes a number of
ADSL-subscriber lines and concentrates these to a single
ATM (Asynchronous Transfer Mode) line.
DSL Modem
Short for modulator-demodulator, this hardware device converts
ATM cells to Ethernet packets and vice versa in the use
of DSL.
Dynamic IP
Each time you go online, your Internet Service Provider will
assign your computer a different IP address for the duration
of your Internet session.
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E
E1
This signal format carries data at a rate of 2.048 million
bits per second and can carry 32 channels of 64 Kbps each.
E1 carries at a somewhat higher data rate than T-1 because,
unlike T-1, it does not do bit-robbing and all 8 bits per
channel are used to code the signal.
EtherLoop
EtherLoop is a proprietary technology from Nortel, short
for "Ethernet Local Loop."
Ethernet
The local area network protocol used in most PC networks.
Typically, most Ethernet networks support data transmission
speeds up to 10 Mbps and are arranged as either
bus or star/hub.
Ethernet Connection
A high-speed direct connection to a network where an Ethernet
Network Interface Card (NIC) is installed so that the user
can access any host connected to the network.
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F
Firewall
A firewall is a security device that controls unauthorized
parties to access a computer or network of computers via
the Internet.
FTTC
Fiber To The Curb – a network where an optical fiber
runs from the telephone switch to a curbside distribution
point close to the subscriber where it is converted to copper
pair.
Frame Relay
A fast-packet technology initially defined as an ISDN frame-mode
service. Frame relay uses a minimal set of Data Link Layer
procedures across the User-to-Network Interface (UNI),
providing unacknowledged transfer of variable-length frames
between users. Additional Layer 2 and 3 functions must
be provided by the end users.
Full Duplex
This refers to the simultaneous transmission of data in two
directions. In full-duplex mode, data you transmit does
not appear on your screen until it has been received and
sent back by the other party. This enables you to validate
that the data has been accurately transmitted.
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H
HDSL
High-Bit-Rate Digital Subscriber Line – a technology
that is of higher speed and is generally used as a substitute
for T1/E1. It is located in systems that need more power
than ADSL such as business phone systems and campus-based
networks.
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I
IDSL
ISDN Digital Subscriber Line- is an ISDN based DSL technology
developed originally by Ascend Communications.
Infotainment
A combination of information and entertainment (such as
the traditional elements of video, film, graphics, animation,
music, audio, and text). Often characterized by hyperlinks
among the various media.
Internet
The Internet is a decentralized, worldwide network of computers
that can communicate with each other.
Intranet
An intranet is a computer network established by businesses
and organizations to facilitate the internal communications
and information sharing.
IP Address
Internet Protocol Address – just like each house has
an address, your computer has an ‘address’. The
IP address is an assigned number that uniquely identifies
each computer connected to a TCP/IP network and consists
of components that identify the individual computer from
other computers on the Internet as well as the network and
sub-networks its belongs to. The IP address appears in a
string like this: 168.68.999.9.
IP Video
IP video is an encoding mechanism that is used to transmit
motion video clips over an IP network.
IP Voice
IP voice technology enables voice traffic to be transmitted
over any network which uses the Internet Protocol technology,
including LANs, WANs, and the Internet.
ISDN
Integrated Services Digital Network - a wide-area network
(WAN) oriented data communication service provided by telephone
companies. It provides access to both the circuit-switched,
public-switched telephone network and to packet-switched
services, such as X.25 and frame relay. ISDN utilizes digital
local facilities and provides out-of-band signaling capabilities.
ISP
Internet Service Provider – an ISP is a company that
provides individuals and other companies access to the Internet
and other related services such as Web site building and
virtual hosting. Examples: Earthlink, Pacific Bell Internet,
America Online, CompuServe, Prodigy.
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K
Kbps
Kilobits (or thousands of bits) per second.
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L
LAN
Local Area Network – is a network that connects computers
within a geographically limited area together and lets them
communicate with each other to share documents and expensive
devices such as laser printers.
Line Card
A line card is a circuit pack that sends signals from the
central office to equipment used on the customer's premises,
providing the intelligence needed to make terminal equipment
work.
Load Coil
A metallic, doughnut-shaped device used on local loops to
extend their reach. Load coils severely limit the bandwidth
in digital communications.
Local Loop
The local loop is a two-wire non-loaded copper wire pair
with no bridged taps. The local loop is terminated at the
customer's premises on a standard network interface that
is supplied by either the customer or vendor.
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M
Mbps
Megabits (or millions of bits) per second.
Microfilters
The microfilter is used to protect the DSL signal from being
contaminated by any signal noise from voice service, allowing
both voice and data to share common inside wiring.
Modem
Originally short for modulator/demodulator, the term 'modem'
has become common usage meaning an electronic device that
modulates an analog carrier, enabling digital information
to be sent over analog transmission facilities. It connects
a computer to a phone line.
MSO
Multiple Service Operator—or cable provider.
Multiplexing
Transmitting several messages simultaneously on the same
circuit or channel.
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N
NAP
Network Access Point - is a high-speed interconnection service
that gives Internet service providers access to the new Internet
infrastructure.
Narrowband
Traditionally, 'narrowband' means a channel with bandwidth
less than, or equal to, one voice-grade line. With advances
in network technology, narrowband has come to be associated
with any channel operating at less than 1.544 Mbps, such
as Narrowband ISDN (NISDN). Contrast with Broadband and
Wideband.
NIC
Network Interface Card - is a circuit board that allows you
to connect your computer to a network. Most NICs are designed
for a particular type of network, protocol, and medium,
although some can serve multiple networks.
NID
Network Interface Device – is a device that terminates
copper pair from the serving central office at the user's
destination and which is typically located outside that location.
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P
PC Card
Term used for laptop NIC cards.
POTS
Plain Old Telephone Service— basic analog telephone
service with no frills or special functions.
POP
Point of Presence - the point within a Local Access and Transport
Area (LATA) at which the Inter-exchange Carrier (IEC) establishes
itself. The POP provides the IEC with LATA access and enables
the Local Exchange Carrier (LEC) to access inter-LATA services.
Also, the consolidation point in a local calling area where
traffic is routed to an Internet Service Provider (ISP).
POTs Splitter
A POTS (Plain Old Telephone Service) splitter, also known
as a low-pass/high-pass filter, is a device that separates
the voice portion of the Sprint FastConnect line from the
data portion of the line. The customer premises splitter "splits" the
analog voice signal from the digital data signal and allows
two wires to simultaneously activate phone jacks and others
to act as data jacks to the modem. The splitter at the
central office, also known as the DSLAM (Digital Subscriber
Line Access Multiplexer), allows for separate POTS and
DSL signals, which go to the PSTN (Public Service Telephone
Network) and the Sprint ATM Network respectively.
PPPoE
Point to Point Protocol over Ethernet— PPPoE is software
that works with an NIC to simulate a dial-up session and
allows dynamic IP address assignment.
PBX
Private Branch Exchange - is a private telephone switch that
provides switching (including a full set of switching features)
for an office or campus. PBXs often use proprietary digital-line
protocols, although some are analog-based.
PSTN
Public Switched Telephone Network— is the dial-up,
circuit-switched telephone network.
PVC
Private Virtual Circuit - is a point-to-point circuit from
the customer's premise equipment to either their ISP or
Enterprise Network.
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R
RADSL
Rate Adaptive Digital Subscriber Line - this technology is
any rate-adaptive DSL modem but may specifically refer
to a proprietary modulation standard designed by Globespan
Semiconductor.
Repeater
This is a device that receives a signal on an electromagnetic
or optical transmission medium, amplifies the signal, and
then retransmits it along the next leg of the medium. Repeaters
overcome the attenuation caused by free-space electromagnetic-field
divergence or cable loss. A series of repeaters make possible
the extension of a signal over a distance. In addition
to strengthening the signal, repeaters also remove the
'noise' or unwanted aspects of the signal.
Router
A device that routes data between networks using IP addressing.
Routers provide firewall security.
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S
SDSL
Symmetric Digital Subscriber Line – this technology
is a version of DSL that supports one speed regardless of
the information flow. In other terms, the upload speeds and
download speeds are the same. It is used in an environment
that needs symmetric data transmission such as video conferencing.
SOHO
Small Office Home Office— a category of remote users.
Splitter
A device that separates the ADSL signal into the voice and
data components. More generally, a device that separates
signal components based on their frequency content. Filters
which separate high frequency (ADSL) and low frequency
(POTS) signals at both the end-user and central-office
end points.
Static IP
Static IP is an IP address that stays the same each time
you connect to the Internet. It is permanently assigned
to a specific computer and is ideal for people who require
a permanent IP address.
Switch
A device used to forward data packets from one segment of
the network to another and that establishes communication
channels between end users. A circuit switch provides dedicated
paths to communicating entities.
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T
T-1
A point-to-point digital communications circuit
that can transmit a digital signal at 1.544 Mbps. It is used
to link large computer networks such as those that make up
the Internet.
Telco
The telephone-operating company or the local provider of
telephone service.
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U
Upstream
Upstream refers to the data flow from your computer to the
Internet or LAN (data you send). If you are transferring
large files from your computer to another location or to
the Internet, then you may need higher upstream bandwidth
than the typical user. DSL allows you to send or upload
large amounts of information and music or video files in
lightning fast speeds compared to dial-up.
USB/USP
Universal Serial Bus or Port— a connection on a computer
that is universally compatible with many types of devices,
such as printers, speakers, mice, etc. Can support speeds
of up to 12 Mbps.
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V
v.90
This is an international standard for 56K data communications.
v.92
This is a new international standard for 56K data communications.
This standard increases the upload speeds, allows a data
call to be put on hold to take an inbound voice call, and
shortens the time to make a connection.
VDSL
Very High Bit-Rate Digital Subscriber Line – this technology
is proposed for shorter local loops, perhaps up to 3000 ft.
It provides 13 - 53 Mbps downstream and 1.5 - 2.3 Mbps upstream
and can easily deliver applications like video-on-demand.
VC
Virtual Circuit – is an interface between an Access
Node and a network. It may have multiple physical connections
although it may also carry all signals across a single physical
connection.
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W
WAN
Wide area network - any network that covers an area larger
than a single building or campus.
Wideband
The term 'wideband' is often used to describe a digital-transmission
facility operating at speeds in excess of 1.544 Mbps.
It is also used in the analog domain to describe a channel
with a large bandwidth, (e.g., "the CATV industry
offers a collection of wideband channels").
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X
XDSL
Refers to the general term or family name of all digital
subscriber line products, such as ADSL, IDSL, and SDSL
and many more. DSL technologies use high-end modulation
processes to pack data, voice and video onto copper wires.
The difference between the various products is in the
rate of information transfer, which is based on your
distance from the serving central office (also known
as the DSLAM), line frequencies and technology protocols.
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