10Base-T - an Ethernet local area network that is designed to run on phone lines

2-wire line - The set of two copper wires, loosely wrapped around each other to minimize interference from other twisted pairs in the same bundle, which connect a telephone customer with a switching office. Synonymous with twisted pair

802.3 - an IEEE specification for SCMA/CD based Ethernet networks.

802.11 - a family of IEEE specifications for 1 and 2 Megabits per second (Mbps) wireless Local Area Networks (LANs)

802.11B - an IEEE specification for 5.5 or 11 Megabits per second (Mbps) wireless Local Area Networks (LANs)

802.11HR - an IEEE specification for 11 Megabits per second (Mbps) high-rate wireless Local Area Networks (LANs)

A

Access point - A device that transports data between a wireless network and a wired network. With the help of the HomePortal, a wireless base station is an example of an access point that acts between a wireless node and with other wired PCs and peripherals.

ADSL - See Asymmetric Digital Subscriber Line.

American National Standards Institute (ANSI) - A non-governmental organization delegated with the responsibility of developing and publishing standards for transmission codes, protocols, and high-level languages for use in the United States.

American Standard Code for Information Interchange (ASCII) - A coding method that assigns specific letters, numbers, punctuation, and control codes to a combination of 0s and 1s in a byte. ASCII is the code by which most all personal computers encodes and translates data. ASCII was developed by the American National Standards Institute (see above).

American wire gauge (AWG) - A measurement of wire diameter - the lower the AWG number, the larger the wire diameter. Copper phone wiring usually comes in 24 or 26 AWG.

analog - A continuously varying signal or wave. Telephone transmission and/or switching that is not digital.

ANSI - See American National Standards Institute

applet - Mini-computer programs that can be downloaded quickly and used by computers with a Java-capable browser.

ASCII - see American Standard Code for Information Interchange

Asymmetric Digital Subscriber Line (ADSL) - A group of DSL technologies that are asymmetric, thereby reserving more downstream bandwidth (coming to the user from the Internet) than upstream bandwidth (going from the user to the Internet).  This type of DSL is advantageous for residential users that do not need the same bandwidth speed in both directions. Also see DSL

Asynchronous Transfer Mode (ATM) - A method of data transportation whereby fixed-length cells are sent over a switched network.  Because of its uniform handling of services, one network can meet the needs of many broadband users, for the receipt of voice, video, and data.

ATM - see Asynchronous Transfer Mode

Audio on Demand (AoD) - A type of media that allows the listener the ability to retrieve audio programs instantaneously.

AWG - see American Wire Gauge

B

backbone - The part of a communications network that handles the major traffic using the highest-speed—and often longest—paths in the network.

bandwidth - A measure of the width or capacity of a communications channel. Greater bandwidth allows communication of more information in a given period of time. Bandwidth is generally described either in terms of analog signals in units of Hertz (Hz), which describes the maximum number of cycles per second, or in terms of digital signals in units of bits per second (bps).

Basic Rate Interface ISDN (BRI-ISDN) - The basic rate ISDN interface, which provides two 64 Kilobits per second channels (called B channels) to carry voice or data and one 16 Kilobits per second channel (the D channel) for call information.

bit - The basic unit in data communications, represented as either a one or a zero. When discussing digital data, a small "b" refers to bits, and a capital "B" refers to bytes.

bit rate - the number of bits of data transmitted over a phone line per second

Bluetooth - An open specification for short-range wireless communications created by a consortium of computer and communication companies known as the Bluetooth Special Interest Group.

broadband - Broadband is the largest size bandwidth category, meaning that there are the most channels of data moving over a single communication medium, thus information such as data, voice, and video can be received and sent most quickly.

Broadband Integrated Services Digital Network (BISDN) - A second-generation ISDN technology that uses fiber optics for a network that can transmit data at speeds of 155 Megabits per second and higher.

BISDN - see Broadband Integrated Services Digital Network

byte - A compilation of bits.  ASCII code uses seven information bits and one parity bit for error control, while EBCDIC standards call for eight information bits.  Other less common standards call for more or less bits in a byte.

C

cable modem - A modem that connects your PC to the Internet by way of the cable that is provided by your cable operator and provides a local area network connection.

CAP - see Carrierless Amplitude Phase

carrier - a signal of a specific frequency which is modulated to transmit information

Carrierless Amplitude Phase (CAP) - A type of quadrature amplitude modulation, used for some types of DSL, that stores pieces of a modulated message signal in memory and then reassembles the parts in the modulated wave.

Category 5 - Also known as CAT5.  A category of cabling that is used for local area networks with voice and data needs.

Central Office (CO) - A telephone company facility that handles the switching of telephone calls on the public switched telephone network (PSTN) for a small regional area.

Central Processing Unit (CPU) - The core of a computer, which uses a stored program to manipulate information.

circuit-switched network - A type of network in which a continuous link is established and reserved between a source and a receiver.  This type of network is used in telephony applications to ensure minimal delay and to reserve an appropriate level of transmission capacity for the call.  Most every phone conversation takes place on a circuit-switched network.

CO - see Central Office

common carrier - A company, including telephone and railroads, which serves the general public and is required by law to provide service to any paying customer as long as government rules and regulations are met.

Competitive Local Exchange Carrier (CLEC) - An American term for a telephone company that was created after the Telecommunications Act of 1996.  This legislation gave other companies the right to compete with the existing phone companies (known as Incumbent Local Exchange Carriers, or ILECs) and to use their phone lines.

compression - The process of reducing the representation of information.  This is often needed in order to transmit a specific audio, video, or data file without using a large amount of transmission time or capacity.

CPE - see Customer Premises Equipment

CPU - see Central Processing Unit

crosstalk - Telephone interference from an adjacent channel, i.e., when you are able to hear a person on your telephone line that you did not call.

Customer Premises Equipment (CPE) - Any piece of equipment in a communication system that resides on the customer's premises. Examples include modems, television set-top boxes, telephones and televisions.

D

data transfer rate - The average number of bits per unit of time passing in a data transaction.

DBS - see Direct Broadcast Satellite

dedicated connection - A communication link that operates constantly.

DHCP - see Dynamic Host Configuration Protocol

dial-up connection - A data communication link that is established when the communication equipment (e.g. a modem) dials a phone number and negotiates a connection with the equipment on the other end of the link.

digital signal - A signal that takes on only two values, off or on, typically represented by "0" or "1." Digital signals require less power but (typically) require more bandwidth than analog.

Digital Subscriber Line (DSL) - A generic name for a family of digital lines being provided by CLECs and local phone companies to provide Internet access to their local subscribers.

Digital Subscriber Line Access Multiplexer (DSLAM) - A device found in telephone company central offices that takes a number of DSL subscriber lines and concentrates them onto a single ATM line.

Direct Broadcast Satellite (DBS) - A broadcast technology that uses satellites orbiting the Earth to broadcast television or data signals to an antenna.

Discrete Multi-Tone Modulation (DMT) - A method of transmitting data on copper phone wires that divides the available frequency range into 256 sub-channels or tones, and which is used for some types of DSL.

Discrete Wavelet Multitone (DWMT) - A variation of DMT modulation that improves performance by using wavelets rather than tones to provide additional isolation of sub-channels.

DMT - see Discrete Multi-Tone Modulation

DNS - see Domain Name System

Domain Name System (DNS) - The protocol used for assigning text addresses (such as www.2Wire.com) for specific computers and computer accounts on the Internet.

DSLAM - see Digital Subscriber Line Access Multiplexer

DWMT - see Discrete Wavelet Multitone

E

E-1 - A dedicated digital communication link provided by a European telephone company that offers 2.048 Megabits per second of bandwidth, commonly used for carrying traffic to and from private business networks and Internet service providers.

echo cancellation - The elimination of reflected signals ("echoes") in a two-way transmission created by some types of telephone equipment, used in data transmission to improve the bandwidth of the line.

encapsulation - the technique used to layer protocols

F

FDM - see Frequency Division Multiplexing

fiber optics - Thin strands of ultrapure glass that can be used to carry light waves from one location to another.

Fiber-to-the-Cabinet (FTTCab) - Network architecture where an optical fiber connects the telephone switch to a street-side cabinet where the signal is converted to feed the subscriber over a twisted copper pair.

Fiber-to-the-Curb (FTTC) - The deployment of fiber optic cable from a central office to a platform serving numerous homes. The home is linked to this platform with coaxial cable or twisted pair (copper wire). Each fiber carries signals for more than one residence, lowering the cost of installing the network versus fiber to the home.

Fiber-to-the-Home (FTTH) - The deployment of fiber optic cable from a central office to an individual home. This is the most expensive broadband network design, with every home needing a separate fiber optic cable to link it with the central office.

filter - A device which transmits a specific frequency and stops all other frequencies. 

Firewall - A security product that employs a combination of hardware and software to prevent unauthorized users or traffic from the Internet from gaining access onto a private local area network (LAN).

frame relay - A high-speed packet switching standard used in wide area networks (WANs), often to connect local area networks (LANs) to each other, with a maximum bandwidth of 44.725 Megabits per second.

frequency - The rate at which an electromagnetic waveform (or electrical current) alternates, usually measured in Hertz (Hz).

Frequency Division Multiplexing (FDM) - The transmission of multiple signals simultaneously over a single transmission path by dividing the available bandwidth into multiple channels that each cover a different range of frequencies.

FTTC - see fiber-to-the-curb

FTTH - see fiber-to-the-home

G

G.dmt - Also known as full-rate DSL.  A type of asymmetric DSL technology, based on DMT modulation, that offers up to 8 Megabits per second downstream bandwidth and 1.544 Megabits per second upstream bandwidth. "G.dmt" is actually a nickname for the standard officially known as ITU-T Recommendation G.992.1. (See International Telecommunications Union.) 

G.lite [pronounced "G-dot-light"] - Also known as Universal ADSL. A type of asymmetric DSL technology, based on DMT modulation, that offers up to 1.5 Megabits per second downstream bandwidth and 384 Kilobits per second upstream.  G.lite DSL does not usually require a splitter and is easier to install than other types of DSL, but is generally unacceptable for voice and entertainment applications. "G.lite" is a nickname for the standard officially known as G.992.2. (See International Telecommunications Union.)

G.992.1 - See G.dmt.

G992.2 - See G.lite.

General Switched Telephone Network (GSTN) - See public switched telephone network.

gigabyte - 1,000,000,000 bytes, or 1,000 Megabytes.  See byte.

Graphical User Interface (GUI) - A computer operating system that is based upon icons and visual relationships rather than text. Windows and the Macintosh computer use a GUI.

GSTN - see General Switched Telephone Network

H

HDSL - see High Bit-Rate Digital Subscriber Line

Hertz - see frequency

High Bit-Rate Digital Subscriber Line (HDSL) - A symmetric DSL technology that provides a maximum bandwidth of 1.5 Megabits per second in each direction over two phone lines, or 2 Megabits per second over three phone lines.

High Bit-Rate Digital Subscriber Line II (HDSL II) - A descendant of HDSL that offers the same performance over a single phone line.

High-Definition Television (HDTV) - A television system that provides a significant improvement in picture quality over existing television (NTSC) systems. Most HDTV systems offer more than 1,000 scan lines, in a wider aspect ratio, with superior color equivalent to that of 35mm film and sound fidelity equivalent to that of a CD.

Home Networking - connecting the different electronic devices in a household by way of a local area network (LAN).

HomePNA - see Home Phoneline Networking Alliance

Home Phoneline Networking Alliance - An association of companies who are working on a standard for home phoneline networking. HomePNA technology allows plug-and-play networking through the use of existing telephone wiring.

HomeRF - also known as Home Radio Frequency Working Group.  An industry specification for the interaction of wireless digital communication between PCs and electronic devices in the home.

HTML - see Hypertext Markup Language

HTTP - see Hypertext Transfer Protocol

hub - The point on a network where circuits are connected

Hybrid Fiber/Coax (HFC) - A type of network architecture that includes a combination of coaxial and fiber cables to distribute signals to a group of individual locations (typically 500 or more).

hypertext - Documents or other information with embedded links that enable a reader to access tangential information at specific points in the text.

Hypertext Markup Language (HTML) - The computer language used to create hypertext documents, allowing connections from one document or Internet page to numerous others. HTML is the primary language used to create pages on the World Wide Web.

Hypertext Transfer Protocol (HTTP) - The transport protocol in transmitting hypertext documents around the Internet.  The first part of an address (URL) of a site on the Internet, signifying the document is written in Hypertext Markup Language (HTML).

I

IDSL - see ISDN Digital Subscriber Line

IEEE - see Institute of Electrical and Electronics Engineers

ILEC - see Incumbent Local Exchange Carrier

Incumbent Local Exchange Carrier (ILEC) - A large telephone company that has been providing local telephone service in the United States since the divestiture of the AT&T telephone monopoly in 1982.

Institute of Electrical and Electronics Engineers (IEEE) - A membership organization comprised of engineers, scientists, and students that sets standards for computers and communications.

Integrated Services Digital Network (ISDN) - A circuit-switched communication network, closely associated with the public switched telephone network, that allows dial-up digital communication at speeds up to 128 Kilobits per second.

Interexchange Carrier (IXC) - A long-distance telephone carrier

International Organization of Standardization (ISO) - Develops, coordinates, and promulgates international standards that facilitate world trade.

International Telecommunication Union (ITU) - A United Nations organization that coordinates use of the electromagnetic spectrum and creation of technical standards for telecommunication and radio communication equipment.

International Telecommunication Union/Telecommunication Standardization Sector (ITU-T) - The branch of the ITU that is responsible for telecommunication standardization.

Internet Engineering Task Force (IETF) - The standards organization that standardizes most Internet communication protocols, including Internet protocol (IP) and hypertext transfer protocol (HTTP).

IETF - see Internet Engineering Task Force

Internet Protocol (IP) - The standard signaling method used for all communication over the Internet.

Internet Service Provider (ISP) - An organization offering and providing Internet access to the public using computer servers connected directly to the Internet.

Intranet - A network serving a single organization or site that is modeled after the Internet, allowing users access to almost any information available on the network. Unlike the Internet, intranets are typically limited to one organization or one site, with little or no access to outside users.

IP - see Internet protocol

IP Address - A numeric identifier for your computer.  Just as the post office delivers mail to your home address, servers know to deliver data to your computer based on your IP address.  IP addresses can be dynamic, meaning that your computer "borrows" the IP address for the necessary timeframe, or they can be fixed, meaning that the number solely belongs to your computer.

ISDN - see integrated services digital network

ISDN Digital Subscriber Line (IDSL) - A type of DSL that uses ISDN transmission technology to deliver data at 128 Kilobits per second into an IDSL "modem bank" connected to a router.

ISO - see International Organization of Standardization

ISP - see Internet Service Provider

ITU - see International Telecommunication Union

ITU - T - see International Telecommunication Union/Telecommunication Standardization Sector

J

JPEG - see Joint Photographic Experts Group

Joint Photographic Experts Group (JPEG) - A committee formed by the International Organization of Standardization to set standards for digital compression of still images. Also refers to the digital compression standard for still images created by this group.

K

Kbps - Kilobits per second

Kilobit - One thousand bits.  See also bit.

Kilobyte - One thousand bytes. See also byte.

L

Laser - From the acronym for "Light Amplification by Stimulated Emission of Radiation." A laser usually consists of a light-amplifying medium placed between two mirrors. Light not perfectly aligned with the mirrors escapes out the sides, but light perfectly aligned will be amplified. One mirror is made partially transparent. The result is an amplified beam of light that emerges through the partially transparent mirror.

last mile - see local loop

Local Access Transport Area (LATA) - The geographical areas defining local telephone service. Any call within a LATA is handled by the local telephone company, but calls between LATAs must be handled by long-distance companies, even if the same local telephone company provides service in both LATAs.

LATA - see Local Access Transport Area

Local Area Network (LAN) - A network connecting a number of computers to each other or to a central server so that the computers can share programs and files.

LAN - see Local Area Network

LLC Encapsulation - see Logical Link Control Encapsulation

Logical Link Control (LLC) Encapsulation - a data link-level transmission control mechanism that involves the use of an logical link control header that identifies the protocol being carried. This allows the end device(s) to properly decipher the Protocol Data Unit (PDU). This is accomplished by prefixing the PDU by an IEEE 802.2 LLC header.

Local Exchange Carrier (LEC) - A local telephone company. LECs provide telephone service for phone calls originating and terminating within a single local access transport area (LATA).

M

MAC address - see Media Access Control address

Mbps - Megabits per second

Media Access Control address - a hardware address that has been embedded into the network interface card (NIC) by its vendor to uniquely identify each node, or point of connection, of a network.

Megabit - One million bits

Megabyte - 1,000,000 bytes, or 1,000 kilobytes.  See byte.

microcell - a bounded physical space in which a number of wireless devices can communicate

Millions of Instructions Per Second (MIPS) - a common measure of the speed of a computer processor.

modem (MOdulator-DEModulator) - A device that converts digital data into analog signals and vice-versa for transmission over a telephone or cable line.

Moving Pictures Experts Group (MPEG) - A committee formed by the International Standards Organization to set standards for digital compression of full-motion video. Also stands for the digital compression standard created by this committee.

MPEG-1 - An international standard for the digital compression of VHS-quality, full-motion video.

MPEG-2 - An international standard for the digital compression of broadcast-quality, full-motion video.

multicast - The transmission of information over the Internet to two or more users at the same time.

N

NAP - See Network Access Provider.

narrowband - A designation of bandwidth less than 56 Kilobits per second.

Narrowband ISDN - see ISDN

NAT - see Network Address Translation

NetBIOS - the basic input/output system of the Internet

Network Access Provider (NAP) - Another name for a provider of networked telephone and associated services, usually in the U.S.

Network Address Translation (NAT) - Network Address Translation (NAT) enables a local area network (LAN) to use one set of IP addresses for internal traffic and a second set of IP addresses for external traffic. 

Network Interface Card (NIC) - a card that connects a workstation to a local area network.

Network Service Provider (NSP) - A high-level Internet provider that offers high-speed backbone services.

Network Termination Equipment (NTE) - The equipment at the ends of the communication path.

NIC - see Network Interface Card

N-ISDN - see narrowband ISDN

NSP - see Network Service Provider

O

OC-3 - see optical carrier 3

ONU - see Optical Network Unit

Optical Carrier 3 (OC-3) - An fiber optic line carrying 155 Megabits per second; a U.S. designation generally recognized throughout the telecommunications community worldwide.

P

packet-switched network - A network that allows a message to be broken into small "packets" of data that are sent separately by a source to the destination. The packets may travel different paths and arrive at different times, with the destination sites reassembling them into the original message. Packet switching is used in most computer networks because it allows a very large amount of information to be transmitted through a limited bandwidth.

Passive Optical Network (PON) - a fiber-based transmission network containing no active electronics.

peripheral - An electronic device, such as a printer or scanner, that is not integral to running a computer, but increases the capabilities of PCs.

Plain Old Telephone Service (POTS) - An acronym identifying the traditional function of a telephone network to allow voice communication between two people across a distance. In most contexts, POTS is synonymous with the public switched telephone network (PSTN).

point of presence (POP) - The physical point of connection between a data network and a telephone network.

Point-to-Point Protocol (PPP) - Point-to-Point Protocol is a protocol which allows a computer to access the Internet using a dial-up phone line and a high-speed modem. This can be accomplished over Ethernet (PPPoE), or over Asynchronous Transfer Mode (ATM; PPPoA).

PON - see Passive Optical Network  

POP - see Point of Presence

POTS - see Plain Old Telephone Service

POTS splitter - A device that uses filters to separate voice from data signals when they are to be carried on the same phone line, required for several types of DSL service.

powerline networking - a type of home networking that uses existing power lines within the home.

PPPoA - Point to Point Protocol over ATM.  See Point to Point Protocol

PPPoE - Point to Point Protocol over Ethernet.  See Point to Point Protocol

Private Branch eXchange (PBX) - A private phone switching system used within a company that connects telephones to each other, allowing users to make inter-office as well as outbound telephone calls. Most companies now use a digital PBX switching system that utilize digital telephones, and includes features such as voicemail, call managemenet, and caller ID.

PRI-ISDN - see primary-rate ISDN

primary-rate ISDN (PRI-ISDN) - The primary rate ISDN interface provides 23-64 Kilobits per second channels (called B channels) to carry voice or data and one 16 Kilobits per second signaling channel (the D channel) for call information.

Public Switched Telephone Network (PSTN) - The worldwide communications network that carries phone calls and data.

R

radio frequency (RF) - Electromagnetic carrier waves upon which audio, video, or data signals can be superimposed for transmission.

RADSL - see Rate-Adaptive Asymmetric Digital Subscriber Line

rate-adaptive digital subscriber line (RADSL) - A variation of DSL that uses carrierless amplitude phase modulation, divides the available frequencies into discrete sub-channels and also maximizes performance by adjusting the transmission to the quality of the phone line while in use.

RBOC - see Regional Bell Operating Company

Regional Bell Operating Company (RBOC) - One of the seven local telephone companies formed upon the divestiture of AT&T in 1984. The seven are: NYNEX, Bell Atlantic, BellSouth, Southwestern Bell, U S WEST, Ameritech, and Pacific Telesis.

Residential Gateway - A device that allows multiple devices access to the Internet through one single high-speed Internet connection.

RF - see radio frequency

Request for Comment (RFC) 1483 - RFC 1483 was developed to allow the successful transmission of multiple protocols over ATM networks. This RFC is broken down into two methods of implementation; VC based multiplexing and LLC encapsulation. The breakdown on both are mentioned below.

RJ-45 Plug - Short for Registered Jack-45, the RJ-45 is an eight-wire plug used to connect computers onto a local area network (LAN), especially Ethernets. 

roaming - movement of a wireless node between two microcells.

router - The central switching device in a packet-switched computer network that directs and controls the flow of data through the network.

S

SCSI - see Small Computer System Interface

Service Pack 6 - Service packs are the means by which product updates are distributed. Service packs keep the product current, and extend and update your computer's functionality. Service packs usually include updates, system administration tools, drivers, and additional components. Service packs are cumulative—each new service pack contains all the fixes in previous service packs, as well as any new fixes. You do not need to install a previous service pack before you install the latest one.  Windows NT 4.0 Service Pack 6a is the latest service pack for Windows NT 4.0.

Small Computer System Interface (SCSI) [pronounced "scuzzy"] - A type of interface between computers and peripherals that allows faster communication than most other interface standards, often used to connect PCs to external disk drives.

splitter - 1. For networking applications, a splitter is a device that splits a connection for use by two distinct outputs.  2. For DSL applications, a splitter is a device that sits on the outside of a residence that splits out the voice and data frequencies on the incoming phone line. 

splitterless - a DSL installation that does not use a splitter. 

switch - a device that selects paths or circuits.  Routers are smart switches.

T

T141 - The American National Standards Institute (ANSI) standard for asymmetric digital subscriber line using discrete multitone modulation, which the full-rate ADSL/G.dmt standard is based on.

T-1 - A dedicated digital communication link provided by a telephone company that offers 1.544 Megabits per second of bandwidth, commonly used for carrying traffic to and from private business networks and Internet service providers.

T-3 - A dedicated digital communication link provided by a telephone company that offers 44.75 Megabits per second of bandwidth, commonly used for carrying traffic to and from private business networks and Internet service providers.

TCP - see Transmission Control Protocol/Internet Protocol

TCP/IP - see Transmission Control Protocol/Internet Protocol

terabyte - 1,000,000,000,000 bytes, or 1,000 gigabytes.  See byte.

Time Division Multiplexing (TDM) - A digital data transmission method that takes signals from multiple sources, divides them into pieces which are then placed periodically into time slots, transmits them down a single path and reassembles the time slots back into multiple signals on the remote end of the transmission.

Token Ring - a ring-like type of local area network whereby a “token” is passed to the workstations within the network.

transmission control protocol/Internet protocol (TCP/IP) - A method of packet-switched data transmission used on the Internet. The protocol specifies the manner in which a signal is divided into parts, as well as the manner in which "address" information is added to each packet to ensure that it reaches its destination and can be reassembled into the original message.

U

UAWG - see Universal ADSL Working Group

UDP - see User Datagram Protocol

Uniform Resource Locator (URL) - A text-based address used to identify specific resources on the Internet, such as web pages. URLs are arranged in a hierarchical form that specifies the name of the server on which a resource is located and the name of the file on that server.

Universal ADSL Working Group (UAWG) - An organization composed of leading personal computer industry, networking and telecommunications companies with the goal of creating an interoperable ADSL standard titled the G.992.2 standard, commonly referred to as the G.lite standard.

Universal Serial Bus (USB) - A computer interface with a maximum bandwidth of 1.5 Megabytes per second used for connecting computer peripherals such as printers, keyboards and scanners.

universal service provider (USP) - A company that sells access to phone, data, and entertainment services and networks.

URL - see Uniform Resource Locator

USB - see Universal Serial Bus

User Datagram Protocol - A TCP/IP protocol describing how data packets reach application programs within a destination computer.

USP- see Universal Service Provider

V

Variable Bit Rate (VBR) - A data transmission that can be represented by an irregular grouping of bits or cell payloads followed by unused bits or cell payloads.

VDSL - see Very High Bit-rate Digital Subscriber Line

Very High Bit-rate Digital Subscriber Line (VDSL) - A type of asymmetric DSL that delivers from 13 to 52 Megabits per second downstream bandwidth and 1.5 to 2.3 Megabits per second upstream.

Video on Demand (VOD) - A pay-per-view television service in which a viewer can order a program from a menu and have it delivered instantly to the television set, typically with the ability to pause, rewind, etc.

Virtual Reality Markup Language (VRML) - A computer language that provides a three-dimensional environment for traditional Internet browsers, resulting in a simple form of virtual reality available over the Internet.

VOD - see video on demand

W

WAN - see Wide Area Network

Wide Area Network (WAN) - A network that interconnects geographically-distributed computers or local area networks.

wireless - transmission of data over radio waves rather than wiring.

X

X.25 data protocol - A packet switching standard developed in the mid-1970s for transmission of data over twisted pair copper wire.

xDSL - See DSL.