HDSL Glossary

ATM Asynchronous Transfer Mode, the key emerging technology that uses fixed-length packets or cells to switch voice, data, and video traffic over the local- and wide-area network.

Backbone network The main artery or link for a private or public network. Typically the backbone carries the loin's share of traffic (data, voice, video, or some combination), is capable of carrying significant bandwidth and it is the network to which small/remote networks/links are attached.

Bandwidth A term now used to describe the capacity or amount of traffic (data, voice, video) a certain communications line is capable of accommodating.

BER Bit Error Rate, the standard transmission error rate of a specific media. Fiber optic cable has a BER of 10^-10 which equates to one bit error every week; while standard copper cable has a BER of 10^-7, yielding a bit error every 6 or 7 seconds. Copper cable using HDSL transmission has a BER of 10^-10.

Bridged Tap A left-behind section of cable that was used to provide phone service to a home or business that is connected to a live copper pair but is not terminated.

Campus In networking terms, a campus is defined as multiple buildings or floors within a building, located in close proximity to each other (2 to 3 miles, or 3 to 4 kilometers), that need to share information and resources via a common network/link.

Coax Coaxial cable, a form of shielded copper cable typically used for high-speed transmission of data, video or cable TV.

CopperOptics A PairGain trademark referring to the functionality of the company's HDSL technology. In essence, with PairGain HDSL products, users can achieve fiber optic-quality signal transmission over copper cable.

Crosstalk Line distortion or static that can occur when wire pairs within the same bundle are used for separate signal transmission. Evident with repeatered T1/E1 transmission.

DLC Digital Loop Carrier, a system that multiplexes a large number of analog or digital subscriber line and transports them over a lesser number of copper or fiber circuits between the central office and a remote location.

DSP Digital Signal Processing, the processing of signal transmission using digital techniques.

DSU/CSU Data Service Unit/Channel Service Unit, DSUs convert T1/E1 or lower speed digital data signals to digital transmission signals, while CSUs are the customer's termination devices for T1/E1 services.

Falcon PairGain's product code for a single-chip implementation of DASL, currently in development.

FDDI Fiber Distributed Data Interface, a network backbone technology that uses a fiber ring to connect critical resources, capable of transmitting at 100 mbps.

Fiber Short for fiber optics, a transmission medium or cable made of strands of glass or plastic. Light is used to pass data, voice or video signals. It typically yields better signal quality and exceptionally high bandwidth.

Frame Relay A streamlined packet switching technique designed to provide high-speed frame or packet switching with minimal delay and efficient bandwidth usage.

HDSL High-bit-rate Digital Subscriber Lline, a standard defined by the T1E1.4 standards committee, designed to be a cost-effective method of delivering T1/E1 line speeds over unconditioned copper cable.

HiGain a PairGain trademark, designating the company's family of carrier HDSL product.

ISDN Integrated Services Digital Network, a CCITT networking standard devised to provide end-to-end, simultaneous handling of digitized voice and data traffic on the same link.

Kbps Kilobits per second, 1,000 bits per second.

LAN Local Area Network, the means by which a local community of users and workgroups can share information and resources electronically. many communications protocols are used to accomplish this, the most prevalent of which are Ethernet and Token Ring.

Last Mile A reference to the local loop, the distance between a local telco office and the end user, a distance actually about 2 to 3 miles, or 3 to 4 kilometers.

Local Loop See Last Mile.

Mbps Megabits per second, one million bits per second.

PBX Private Branch Exchange, a telephone switching system located at a private network site.

RBOC Regional Bell Operating Company, in the U.S. there are several such companies that were established after the break-up of AT&T.

Repeater An electronic device used to regenerate digital signals and restore signal quality across a certain distance of cable.

Repeatered T1/E1 T1/E1 signal transmission over copper cable using repeaters that are installed roughly every 3,000 to 4,000 ft/1 km.

SDH Synchronous Digital Hierarchy, a fiber backbone protocol for countries where E1 is a standard.

SNMP Simple Network Management Protocol, a network management standard initially established to allow multi-vendor networking devices to be managed more easily with common management tools.

SONET Synchronous Optical Network, a recently emerging networking standard that utilizes fiber optics to create backbone networks, capable of transmitting at extremely high speeds and accommodating gigabyte-level bandwidth.

SPAROW Signal Processing Adaptive Receiver On Wire, the product name for PairGain's proprietary single-chip implementation of HDSL introduced in 1990.

T1 A standard telecommunications circuit transmitting at 1.544 mbps and used widely in U.S. and Canadian public and private networks.

Telco An abbreviation, commonly used synonymously with telephone company.