|DSL vs. Cable|
modems are the cable companies answer to high speed data access. This technology
was developed to provide video-on-demand or other high bandwidth services.
The technology is sound but has quite a few inherent problems with the
A local loop of fiber cable must be available near all residences (this
is not for business users) to use this service. The problem is the very
small percentage of currently wired users (usually newer buildings or developments).
This dictates that the cable companies must run inordinate amounts of new
fiber that is very expensive to install and very time consuming. The cost
to rewire the US with fiber is estimated at $400 billion and would require
about 30 years to implement.
|DSL is actually a higher speed version of ISDN which itself is an improved, higher speed version of older, analog dial-up modems. ISDN stands for Integrated Services Digital Network or the ability to combine voice and data on the same line. Unfortunately due to lack of any uniform standards or mass deployment to make it cost effective, ISDN never really caught fire. Between the additional phone lines and marginal gain in speed over a 56kbps modem, most users felt that it wasn't worth the hassle. ISDN offers dedicated, always on access but comes with an additional bill for minutes used. ISDN is secure for e-commerce transactions, but at 64k it is painfully slow.|
The Institute of Electrical and Electronic Engineers (IEEE) specification
for Ethernet over unshielded twisted pair cable.
ADSL Asymmetric Digital Subscriber Line. High speed technology utilizing existing phone lines to transmit data. Typical speeds are from 144Kbps to over 8Mbps currently. See DSL Types for more info.
ATM Asynchronous Transfer Mode. High Bandwidth packet technology that uses 53 byte fixed sized cells to deliver data, voice and video.
ATU ADSL Transceiver Unit. Equipment used for DSL technology. In the Central Office it is called ATU-C (central) and in the Customer locations it is called ATU-R (remote). See our home page for diagram.
Backbone A central very high speed fiber network that is used to connect smaller, independent networks.
Bandwidth A term used to describe the number of bits that can move across a communications system in a given amount of time.
BPS Bits per second. The number of bits passing a point every second. The rate of transmission for digital signals.
Broadband Data transmissions of voice, data and video signals over a single medium at high speeds.
Cable Modem Modem designed for use with coaxial cable circuit.
Campus Network A local network between floors of a building or between buildings of close proximity. Usually runs are short distance and without public access.
CAP Carrierless Amplitude Phase Modulation. A two dimensional line code used in ADSL.
CLEC Competitive Local Exchange Carrier. The new competitors to the original Bells after deregulation. See also ILEC.
CO Central Office. The building used by telephone companies to connect local users to their infrastructure.
Concentrator Electronic device used to aggregate several channels or sources into one stream for transmission over one line or link. Opposite of Multiplexer.
CPE Customer Premises Equipment. Terminating equipment supplied by carrier for use at customer site ie. modems, phones, routers.
DACS Digital Access & Cross-Connect System. A digital cross-connect device used to route lines to multiple ports.
Dedicated Circuits Telecommunications lines reserved along predetermined routes for specific customers usually in a point to point configuration.
DNS Domain Name Services. Name (actually numbers) used by servers for identification in a local or global network
Downstream The direction of data returned from the Central Office back toward the user. Usually used with transmission speed (ie. 1.5Mbps downstream)
DSL Digital Subscriber Line. Technology that combines two way voice and data transmissions at very high speeds over normal phone lines. See DSL Types for more info.
DSLAM Digital Subscriber Line Access Multiplexer. Equipment used in the Central Office or Intranet to concentrate local users onto a fiber Backbone
DSP Digital Service Provider. New breed of Internet Service Providers who specialize in direct, digital Internet connections like Flashcom.
DSU Digital Service Unit. Digital device at customer premises to facilitate xDSL service. Also known as a Modem or Router.
E1 The European equivalent of our T1 that operates at 2.048Mbps.
E-Commerce Electronic Commerce. Electronic transactions between business and customers via the Internet. These are typically private and secure.
Ethernet Term used to describe a baseband LAN specification originally designed by Xerox. IEEE 802.3 describes the current standards for this protocol.
Firewall A secure gateway or virtual wall between two different computer networks that will prevent unauthorized use or access.
Fractional T1 A portion of a T1 circuit that has been divided into 24 separate 64Kbps channels. Actual size is a multiple of 64.
Frame Relay A data communication technology based on packet switching of variable length frames that are protocol independent.
FTP File Transfer Protocol. Method for accessing and transfer of files to or from an Internet Server or Workstation.
Gbps Giga bits per second. 1,000,000,000 (one billion) bits per second, a measure of telecommunications speed. A thousand Megabits.
HDSL High bit rate Digital Subscriber Line. See DSL Types for full definition.
HTU HDSL Transceiver Unit. Electronic device used for the sending and receiving of HDSL transmissions. At the CO side it is called HTU-C (central office) and on the user side it is called HTU-R (remote).
IDSL Integrated Digital Subscriber Line. An ISDN based version of DSL using 2BIQ line code.
ILEC Incumbent Local Exchange Carrier. All the original Bells are called ILEC's after the Telecommunications Act deregulation. All new competitors are known as CLEC's
Internet Global network of interconnected commercial, governmental and educational computers using TCP/IP as a communications protocol.
InterNIC Co-op between National Science Foundation and Network Solutions for registration and tracking of Internet domain names.
Intranet A private network that uses Internet software and standards.
IP Internet Protocol. A software standard that controls the flow and routing of content between Internet devices or machines.
ISDN Integrated Services Digital Network. Public circuit switched network that combines voice and data into a single medium. Usually runs at 64K or 128K, predecessor to DSL technology.
ISP Internet Service Provider. Company that provides connection to the Internet typically via a dialup link (ie. AOL, Always Over Loaded) . See DSP for a better definition of service.
IXC Inter Exchange Carrier. All telecommunications companies who provide long distance service, aka Common Carriers.
Kbps Kilo Bits Per Second. A measure of time relating to telecommunications speeds. One kilobit is 1,000 bits of information, the higher the number the faster the transmission speed.
LAN Local Area Network. A data communications networks of computers, printers, file servers, etc.. in a local environment.
LEC Local Exchange Carrier. Provider of local telecommunications services. See also CLEC, ILEC
Local Loop Also called the "last mile". The length of telephone wire from the local Central Office to it's final termination at customer premises. Usually about 1-3 miles or less.
Mbps Mega Bits Per Second. Like Kbps a measure of transmission rates. One Megabit equals 1,000 kilobits. 1.5Mbps DSL is a heck of a lot faster than your current analog service.
Modem An antique electronic device that was used to modulate or change your computers digital output to an analog form for transmission over separate, dedicated phone lines. The old school of data transmission.
Multiplexer An electronic device that allows one source to be split into multiple channels. The opposite of a concentrator.
NAP Network Access Provider. Service or company that provides actual entry into the Internet backbone. Also called a DSP or Flashcom.
NIC Network Interface Card. The hardware that handles the protocol conversion between your computer and a connected network. Used in DSL service to talk to router.
NSP Network Service Provider. Company who provides connection to networks or Internet. Also called ISP, DSP, ILEC, CLEC or Flashcom.
NTU Network Termination Unit. Equipment to facilitate DSL network access at customer premises. Also called a router.
POP Point of Presence. Location at which to gain access to a public or private network.
POTS Plain Old Telephone Service. As it sounds, your basic telephone service.
Protocol A format or rules two or more computers must follow in order to communicate.
RADSL Rate Adaptive DSL. See DSL Types for more info.
RBOC Regional Bell Operating Companies. The five companies created after the breakup of AT?, Bell Atlantic, Bell South, Ameritech, Southwestern Bell and US West.
Repeater Electronic device used to regenerate and enhance signal quality over long cable distances.
Router Electronic device that transmits and receives data packets in a network.
SDSL Symmetrical Digital Subscriber Line. See DSL Types for more info.
SMDS Switched Multimegabit Data Service. A public packet switching service used by telephone companies in major metropolitan areas.
SONET Synchronous Optical Network. A network standard that uses fiber optics to transmit data at gigabit level bandwidth.
T1 Digital transmission at 1.544Mbps. T1 is the most common transmission technique used in North America.
T3 Digital transmission at 45Mbps. Basically 30 T1 circuits.
TCP/IP Transmission Control Protocol/Internet Protocol. Open communication protocol that allows computers with different operating systems to communicate with each other on the Internet.
Twisted Pair Cable of two 18 to 24 gauge solid copper strands twisted around each other. The twisting helps protect against electromagnetism and Radio Frequency Interference (RFI).
Upstream Refers to transmission speed from user to the Internet. Opposite of Downstream.
VDSL Very high bit rate Digital Subscriber Line. See DSL Types for more info.
VPN Virtual Private Network. A network service that is provided over a public network that is secure and works like a private network.
WAN Wide Area Network. A network with devices over a wide geographical area.
xDSL Refers to all variations of the DSL family or technologies.