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0-9
56K
The term 56K refers to a new generation of modems that improve the speed
of communication between personal computers and the Internet. The previous
speed standard of v.34 provided communication at speeds as high as 33,600
bits per second (bps). The new 56K modems increase that speed to a theoretical
maximum of 57,600 or 56Kbps. In the past, two different technologies
emerged enabling 56K communication: K56flex and x2. They have been replaced
by a new, international standard for 56K data communications known as
v.90.
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A
ADSL
Asymmetric Digital Subscriber Line: Modems attached to twisted pair
copper wiring that transmit from 1.5Mbps to 9Mbps downstream (to the
subscriber) and from 16Kbps to 800Kbps upstream, depending on line distance.
ADSL Lite
A lower data rate version of Asymmetric Digital Subscriber Line (ADSL)
technology.
Analog
A signal that can take on any value in a range. Contrast with Digital.
Asymmetrical
Offering 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
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
- 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.
- 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
In telecommunications networks, a bridge is a product that connects
a local area network (LAN) to another local area network that uses the
same protocol (for example, Ethernet or Token Ring). A bridge 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 (or
LANs).
Broadband
A term for high-speed, high-capacity Internet and data connections.
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C
Cable Modem
A device that attaches between a PC and an analog cable TV distribution
plant that can modulate and demodulate user data onto/from the cable
plant. It allows cable TV companies to provide data transmission capabilities
to customers over existing infrastructure.
CAP
Carrier-less Amplitude/Phase (CAP) modulation; incoming data modulates
a single carrier that is then transmitted down a telephone line. The
carrier itself is suppressed before transmission (it contains no information,
and can be reconstructed at the receiver), hence the adjective "carrier-less."
CAP and DMT are two modulation systems currently on the market for ADSL.
CDSL
Consumer Digital Subscriber Line (CDSL) is a proprietary technology
trademarked by Rockwell International.
Channel
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 always associated, the term channel can refer to this two-way path.
CPE
Customer Premises Equipment - Any equipment provided by the customer
at their premises.
Customer Self-Install
(CSI)
Customer Self-Install uses customer-installed low-pass microfilters
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. The filters are placed
between the analog devices and the phone jack(s) and do not require
any tools for installation.
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D
Data
A formal representation of raw material from which information is constructed
via processing or interpretation.
DHCP
Dynamic Host Configuration Protocol. DHCP lets a network administrator
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) multicarrier 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.
CAP and DMT are two modulation systems currently on the market for ADSL.
Downstream
Downstream refers to "host to end-user" (receive, download) direction.
DSL
Digital Subscriber Line (DSL) technology provides a dedicated digital
circuit between a residence and a telephone company's central office,
allowing high-speed data transport over existing twisted copper telephone
lines.
DSL Gateway
DSL Gateways are made up of DSL network equipment, housed in specialized
buildings, that enable residential and business customers to receive
DSL Internet Service who previously had been located too far from their
central switching office to get the service. In effect, 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. Specifically, a device which
takes a number of ADSL subscriber lines and concentrates these to a
single ATM line.
DSL Modem
Short for MOdulator-DEModular, this hardware device converts ATM cells
to Ethernet packets and visa-versa in the use of DSL.
Dynamic IP Addressing
An IP address is assigned to the customer for their current session
or some other ISP-specified amount of time. The alternate to a dynamic
IP address is a Static IP address.
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E
EtherLoop
EtherLoop is currently a proprietary technology from Nortel, short for
"Ethernet Local Loop."
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 security device that controls access from the Internet to a local
network.
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. The Layer 2 protocol uses LAPF-Core
procedures. The network discards any frame with bit errors. Frame relay
offerings today primarily offer permanent virtual circuit (PVC) services
independent of ISDN. Switched virtual circuit (SVC) services will use
ISDN-like signaling for call control.
Full Duplex
Refers to the transmission of data in two directions simultaneously.
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 (HDSL) technology is generally
used as a substitute for T1/E1.
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I
IDSL
ISDN-based DSL technology developed originally by Ascend Communications.
Info-tainment
A combination of traditional elements of video, film, graphics, animation,
music, audio, and text for the purposes of providing information and/or
entertainment. Often characterized by hyperlinks among the various media.
Internet
The globally interconnected collection of IP protocol based networks.
Intranet
A corporate network that uses an IP network structure, together with
Web servers and browsers. Intranets are generally used to provide information
such as benefits plans, etc. to corporate employees in an easily accessible
fashion.
IP
Internet Protocol
IP Video
An encoding mechanism that is used to transmit motion video clips over
an IP network.
IP Voice
A technology that enables voice traffic to be transmitted over any network
that uses IP (the Internet Protocol), including LANs, WANs, and the
Internet.
ISDN
Integrated Services Digital Network - A wide area network (WAN) oriented
data communication service provided by telephone companies. ISDN is
unique among WAN services in that it provides access both to 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 - Examples: Pacific Bell Internet, America
On Line, CompuServe, Prodigy.
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K
kbps
Kilobits (or thousands of bits) per second. When used in reference to
transmission rates, the prefix kilo means exactly one thousand.
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L
LAN
Local Area Networks - A network of interconnected computers that is
distinguished by its small geographical size (typically measured in
meters), privately owned, high-speed (usually measured in megabits per
second), and low error rate (typically 1 bit in a trillion).
Line Card
A line card is a circuit pack which sends signals from the Central Office
to equipment used on the customer's premises. These signals provide
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 2-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 which is supplied by either the customer or a vendor.
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M
Mbps
Megabits (or millions of bits) per second. When used in reference to
transmission rates, the prefix mega means exactly one million.
Microfilters
The microfilter is used to protect the DSL signal from being contaminated
by any signal noise from your voice service, allowing both voice and
data to share common inside wiring.
Modem
Originally short for modulator/demodulator, modem has become common
usage. An electronic device that modulates an analog carrier, enabling
digital information to be sent over analog transmission facilities.
MSO
Multiple service operator synonymous with cable provider.
Multiplexing
Transmitting several messages simultaneously on the same circuit or
channel.
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N
NAP
Network Access Point (NAP) is a high-speed interconnection service that
gives Internet Service Providers access to the new Internet infrastructure.
Narrowband
Traditionally, 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 1.544Mbps, such as
Narrowband ISDN (NISDN). Contrast with Broadband and Wideband.
Network Interface
Card (NIC)
A expansion board you insert into a computer so the computer can be
connected to a network. Most NICs are designed for a particular type
of network, protocol, and media, although some can serve multiple networks.
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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 facilities.
POP
Point of Presence - The point within a Local Access and Transport Area
(LATA) at which the Interexchange 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).
PPPoE
Point to Point Protocol over Ethernet. PPPoE is software that works
with a NIC to simulate a dial-up session and allows dynamic IP address
assignment.
Private Branch Exchange
(PBX)
A PBX 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 - The dial-up, circuit-switched telephone
network.
PVC
Private Virtual Circuit (PVC) is a point-to-point circuit from the customer
premise equipment to either their Internet Service Provider (ISP) or
Enterprise Network.
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R
RADSL
Rate Adaptive Digital Subscriber Line (RADSL) technology is any rate
adaptive DSL modem, but may specifically refer to a proprietary modulation
standard designed by Globespan Semiconductor.
Repeater
In telecommunication networks, a repeater 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 (SDSL) technology is a 2-wire implementation
of HDSL.
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. A filter which separate high frequency (ADSL) and
low frequency (POTS) signals at both the end user and central office
end points.
Static IP Addressing
An assigned IP address used to connect to the Internet The IP address
stays with the customer's computer. Common needs for static IP include:
web or email server hosting, virtual private networks (VPN), and remote
connection to secure corporate networks or some external applications.
The alternate to a Static IP address is a Dynamic IP address.
Switch
A device that can establish communication channels between end-users.
A circuit switch provides dedicated paths to communicating entities;
a store and forward switch shares paths on a statistically multiplexed
basis.
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T
T-1
- A point-to-point
digital communications circuit that carriers 24 64,000 bits/ s channels,
each of which may be used for data or digitized voice.
- Digital Transmission
Level 1 (1.544Mbps)
Telco
The telephone operating company or the local provider of telephone service.
TN
Telephone Number
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U
Upstream
Upstream refers to "end-user to host" (transmit, upload) direction.
The direction from an end-user to the network.
USB
Universal Serial Bus or Port, connection port on a computer that is
universally compatible with many types of devices, such as, printers,
speakers, mouse, etc. Can support speeds of up to 12Mbps.
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V
v.90
An international standard for 56K data communications.
v.92
A new, international standard for 56K data communications. This standard
increases the upload speed, 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 (VDSL) technology is proposed
for shorter local loops, perhaps up to 3000 ft. It provides 13 - 53Mbps
downstream and 1.5 - 2.3Mbps upstream.
Virtual Circuit (VC)
Interface between Access Node and network. May have multiple physical
connections although may also carry all signals across a single physical
connection.
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W
WAN
Wide area network.
Wideband
Variously defined. The term wideband is often used to describe a digital
transmission facility operating at speeds in excess of 1.544Mbps. 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 family of digital subscriber line technologies, such as
ADSL, HDSL, IDSL, RADSL, SDSL and VDSL.
