DSL Glossary

A

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.

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.

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.

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.

D

Data
A formal representation of raw material from which information is constructed via processing or interpretation.

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. We offer two ADSL (Asymmetric Digital Subscriber Line) Internet Service options to support information transfer rates of 1.5Mbps downstream and 384Kbps upstream, or 384Kbps downstream and 128Kbps upstream.

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.

E

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.

F

Firewall
A security device that controls access from the Internet to a local network.

I

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.

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.

K

kbps
Kilobits (or thousands of bits) per second. When used in reference to transmission rates, the prefix kilo means exactly one thousand.

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.

M

Mbps
Megabits (or millions of bits) per second. When used in reference to transmission rates, the prefix mega means exactly one million.

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.

N

NAP
Network Access Point (NAP) is a high-speed interconnection service that gives Internet Service Providers access to the new Internet infrastructure.

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.

O

1 Mb Line
One Message rate Business phone line. A phone line you pay a single monthly rate for. (Main Business Line)

P

PC Cards
Term used for laptop NIC cards.

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.

R

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.

S

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 filters 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.

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)

TN
Telephone Number.

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.

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.

W

WAN
Wide area network.