Local Exchange Carrier. Generally, a larger corporation or organization (e.g., university) that operates as its own local exchange carrier (LEC) as a means of obtaining better carrier rates for itself, possibly
selling services to others for a profit. ELECs could be considered a subset of CLECs. See also LEC, ILEC, and ELEC.
enterprise network. A term
for a widely dispersed, multifaceted telecommunications network for a particular purpose or organization; a term for all of an organization's telecommunications networking services and equipment.
Ethernet. A LAN used to connect
devices within a single building or campus at speeds up to 10 Mbps. Within the OSI model, Ethernet is defined at layer one (physical) and layer two (data link). Based on Carrier Sense Multiple Access/Collision
Detection (CSMA/CD), Ethernet works by simply checking the wire before sending data. Sometimes two stations send at precisely the same time in which case a collision is detected and retransmission is attempted. See
A LAN used to connect devices within a single building or campus at speeds up to 100 Mbps. Within the OSI model, Fast Ethernet is defined at layer one (physical) and layer two (data link). Like Ethernet, Fast
Ethernet uses CSMA/CD.
frame relay (FR). A
high-speed packet-switched data communications service, similar to X.25. Frame relay is a leading contender for LAN-to-LAN interconnect services, and is well suited to the bursty demands of LAN environments. See
also permanent virtual circuit and switched virtual circuit.
ILEC. Incumbent Local
Exchange Carrier. A new term that describes traditional local telephone companies that, prior to deregulation of the telephone industry, had the exclusive right and responsibility to provide local telephone service.
ILEC delineates these service providers from the new competitive providers (CLECs) and enterprise providers (ELECs). The term "local exchange carrier" (LEC) is used as the generic term for all three. See LEC, CLEC, and ELEC.
Integrated Services Digital Network (ISDN). ISDN provides standard interfaces for digital communications networks and is capable of carrying data, voice, and video over digital circuits. ISDN protocols are used worldwide for connections to public ISDN networks or to attach ISDN devices to ISDN-capable PBX systems (ISPBXs).
Developed by the International Telecommunications Union (ITU [previously the CCITT]), ISDN includes two user-to-network interfaces: basic rate
interface (BRI) and primary rate interface (PRI). Note: See separate entries for basic rate interface and primary rate interface.
An ISDN interface contains one signaling channel (D-channel) and a number of information channels ("bearer" or B channels). The D-channel is
used for call setup, control, and call clearing on the B-channels. It also transports feature information while calls are in progress. The B-channels carry the voice, data, or video information.
interface. A point of
connection between two systems, networks, or devices.
Internet. The world's largest
computer network. The Internet originated from a research effort initiated by the U.S. Government and was initially used to connect defense contractors and U.S. universities. Today, its nature is more commercial,
and it is becoming the preferred method of linking businesses and individuals' computers to one another.
Internet Service Provider (ISP). A
telecommunications company that provides subscriber access to the Internet.
- Internet access. The physical telephone circuit connection
between the subscriber and the nearest Internet access node.
Kbps, Gbps, Mbps
- kilobits per second (Kbps). A measure of bandwidth capacity
or transmission speed. It represents a thousand bits per second.
- gigabits per second (Gbps). A measure of bandwidth capacity
or transmission speed. It represents a billion bits per second.
- megabits per second (Mbps). A measure of bandwidth capacity
or transmission speed. It stands for a million bits per second.
Intranet. A local network, for
example, an office network, where there are internal web servers accessible to computers in the office, but not accessible from outside the company. Many intranets are protected from exterior access by various
security devices, like firewalls.
measure of the temporal delay. Typically, in xDSL, latency refers to the delay in time between the sending of a unit of data at the originating end of a connection and the reception of that unit at the destination
Layer 2. Covad manages a Layer 2 network, which means that we are able to carry any Layer 3 protocol (IP, IPX, Appletalk) that our customers wish to transport to their clients. It also means that Covad cannot see the Layer 3 packet as it is encapsulated within our Layer 2 ATM cell, making customers' data secure as it travels across the Covad Regional Network. Finally, Covad's Layer 2 network never crosses the public Internet, adding to the security of customer data."
LEC. Local Exchange Carrier. A local
telephone company (either a Bell Operating Company [BOC] or an independent [e.g., GTE]) that traditionally had the exclusive, franchised right and responsibility to provide local transmission and switching services.
Prior to divestiture, the LECs were called telephone companies or telcos. With the advent of deregulation and competition, LECs are now known as ILECs (incumbent LECs). This terminology delineates them from CLECs
(competitive LECs) and ELECs (enterprise LECs). See CLEC and ELEC.
local area network (LAN). A data
communications network covering a small area, usually within the confines of a building or floors within a building; a relatively high-speed computer communications network for in-building data transfer and
applications. Common LAN protocols are Ethernet and Token Ring. See also CAN, MAN, WAN.
local loop. A generic term
for the connection between the customer's premises (home, office, etc.) and the provider's serving central office. Historically, this has been a wire connection; however, wireless options are increasingly available
for local loop capacity. Also colloquially referred to as "the last mile" (even though the actual distance can vary).
long distance. The
communication of information to a destination outside the local calling area. Also called "long haul" traffic.