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Glossary of Data Network Terminology
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ADSL (Asymmetric Digital Subscriber Line): Refer to Digital Subscriber Line.
Analog: A transmission method that uses continuous electrical signals varying in amplitude or frequency in response to changes, for example, in sound, light and position impressed on a transducer in the sending unit. The opposite of analog is digital.
Asynchronous: A transmission method that transfers information one character at a time and is delineated by a start and stop indicator at the beginning and end of each character. The opposite of asynchronous is synchronous.
ATM (Asynchronous Transfer Mode): A method for the dynamic allocation of bandwidth using a fixed-size packet (called a cell). ATM is also known as "fast packet". A switched link layer protocol for transporting multimedia data across wide area, campus, backbone and local area networks.
Authentication: A method of verifying the identity of a person or process.
Backbone: A network of broadband connections between switches.
Bandwidth: The relative range of frequencies that can be passed through a transmission medium without distortion, the greater the bandwidth, the higher the carrying capacity of the transmission circuit. Bandwidth, usually measured in Hertz, is assessed as the number of bits that can be transferred per second.
Bits Per Second: The maximum number of binary information units that a data channel can transmit per second. Often referred to as "bps".
Bridge: A device which forwards traffic between network segments based on data link layer information. These segments must have a common network layer address.
Broadband: A transmission medium that supports a wide range of frequencies. It can carry multiple signals by dividing the total capacity of the medium into multiple, independent bandwidth channels. Each channel operates over a specific range of frequencies.
Broadband Network: A network capable of transmitting voice, video signals, images and data at speeds exceeding 1.5 Mbps.
Cable: A grouping of insulated wires in the same casing.
Central Office (CO): A telecommunications common carrier facility where calls are switched. In local area exchanges, central offices switch calls within and between the 10,000 line exchange groups that can be addressed uniquely by the area code and first three digits of a phone number.
Circuit Switching: A dedicated communication path established between two hosts, on which all packets travel. The telephone system is an example of a circuit switched network.
Co-location: The ability to co-locate Competitor (Licensed Canadian Carrier) owned transmission equipment and fibre cable in a telephone company's central office utilizing power, space and environmental conditioning.
Concentrator: The generic term for a device which aggregates network traffic from various similar sources. For example, a local area network (LAN) concentrator connects a number of LAN devices at a single point.
Data Link Layer: The Operating System Interconnection (OSI) layer responsible to transfer data between two network entities across a single physical connection or series of bridged connections.
Demarcation: Defines the point at which ownership or responsibility for operating and maintaining facilities passes from one party to another. It can be a discrete physical device such as a jack or a virtual location such as the main telephone room.
DEA (Digital Exchange Access): A digital service that replaces analog trunks and connects digital private branch exchanges (PBXs) from a customer's premises to the public switched telephone network (PSTN). Equipment other than PBX may also be connected to DEA provided it conforms to DEA interface specifications (T-1 standard).
Dedicated Access: A direct connection from a terminal to a service, network or computer that is provided for a customer's exclusive use and benefit.
Dial Access: Use of the PSTN to connect a terminal to a service, network or computer.
Digital: A device or method that uses discrete variations in voltage, frequency, amplitude, location, etc. to encode, process or carry binary (zero or one) signals for sound, video, computer data and other information. Digital communications technology generally permits higher speeds of transmission with a lower error rate than can be achieved with analog technology.
Digital Loop Carrier (DLC): Digital Loop Carrier is equipment that bundles a number of individual phone line signals into a single, multiplexed digital signal for local traffic between a telephone company CO and a remote location.
Digital loop carrier systems consist of two parts, a Central Office Terminal and a Remote Terminal. The Central Office Terminal provides the multiplexing/demultiplexing function of individual voice signals to the composite multiplexed signal at the interface between the switching equipment and the DLC. The Remote Terminal provides the multiplexing/demultiplexing function at the interface between the individual subscriber pairs and the DLC.
Digital Subscriber Line Access Multiplexer (DSLAM): A Digital Subscriber Line Access Multiplexer is a mechanism at a phone company's central office that links many customer DSL (digital subsciber line) connections to a single high-speed ATM line.
DNA (Digital Network Access): A national generic access service that provides customers with a single network access for their subrate DS-1 (speeds of up to 56 Kbps) MegaplanÁ services. The service offers customers a common set of features and consistent rates on a national basis.
DS-0: The base unit of digital transmission capacity. One communication channel equals one simultaneous voice grade equivalent, with a communication capacity of 64 Kbps.
DS-1 (T-1): The equivalent of 24 multiplexed DS-0 voice grade channels (1.5 Mbps).
DS-3 (T-3): The equivalent of 28 multiplexed DS-1 channels (44 Mbps).
Electronic Commerce (or e-commerce): In its broadest sense, all commercial activities conducted over computer networks such as the Internet, including e-mail and the promotion and sale of products and services. In its narrowest sense, electronic commerce designates the sale of products and services over the Internet via credit card or electronic fund transfer.
Electronic Mail (or e-mail): A service enabling users to exchange written messages (and computer file enclosures if desired) through computer servers acting as mailboxes. E-mail should not be confused with chat lines, which enable computer users, connected together, to exchange short written messages in real time.
Encryption: Manipulating a packet's data to prevent all but the intended recipient from reading that data. There are many types of data encryption, which are the basis of network security.
Enterprise Data Network: A private network designed to interconnect the data processing devices of a single enterprise. Usually consists of customer-owned LAN equipment and wide area network (WAN) access products, and carrier-provided WAN services.
Ethernet: A shared media link layer protocol for LAN connectivity defined by the Institute of Electrical and Electronics Engineers (IEEE) 802.3 standard to run over various media at a rate of 10 Mbps.
Extranet: All electronic links between related companies (partners, suppliers, distributors and/or customers) that use the same protocols as intranets or the Internet. Extranets can be used to provide access to portions of a company's intranet to outside users. Communications between companies are protected by enciphering and authentication.
Fibre Optics: A technology based on thin filaments of glass or other transparent materials that is used as the medium for transmitting coded light pulses that represent data, image and sound. Fibre optic technology offers extremely high transmission speeds.
Firewall: A combination of software and hardware linking a corporate network to the Internet in such a way that corporate network users are able to access and consult the Internet, but external Internet users cannot gain unauthorized access to the company's computers.
Fractional T-1: A service that uses a portion of a 24 channel DS-1 circuit. It allows 64 Kbps increments from two-channel 128 Kbps through all 24 channels at 1.5 Mbps.
Frame Relay: A wideband (64 Kbps to 1.5 Mbps) packet-based data interface standard that transmits bursts of data.
Gateway: A communications device or program which passes data between networks with similar functions but dissimilar implementations. By this definition, a router is a Layer 3 (network layer) gateway, and a mail gateway is a Layer 7 (application layer) gateway.
Hub: A device connected to several other devices. In a LAN, a hub is used to connect several computers together. In a message handling service, a hub is used to transfer messages across the network.
Information Highway: A network comprising numerous interconnected networks capable of transmitting wideband services, namely voice, data, images, video and interactive communications, at high speed. The highway is a means to communicate with businesses, individuals, schools, hospitals and many other organizations.
Integrated Digital Loop Carrier (IDLC): A Digital Loop Carrier System where the central office terminal portion of the system is integrated with the class 5 switch.
internet (small "i"): While an internet is a network, the term "internet" usually refers to a collection of networks interconnected with routers.
Internet (capital "I"): A "web" of computer networks linked together on a worldwide basis enabling users to communicate with each other and exchange information via TCP/IP protocol-based software (Transmission Control Protocol/Internet Protocol). Internet development is coordinated by the non-profit Internet Society (ISOC). Setup of the Internet was financed with public money, but the network is increasingly commercial in nature.
Internet Address: An IP address that uniquely identifies a node on an internet. An Internet address (capital "I"), uniquely identifies a node on the Internet.
Internet Protocol (IP): The Internet Protocol, defined in STD 5, RFC 791, is the network layer for the TCP/IP Protocol Suite. It is a connectionless, best-effort packet switching protocol.
Internet Service Providers (ISPs): Companies that supply Internet access services to their customers, one of the fastest growing wholesale markets.
Intranet: A replica of the Internet within an organization. Intranets use the same protocols and software as the Internet to facilitate communication and information sharing among company employees or departments.
Layer 3 Switch: A LAN switch which forwards data based on Layer 3 address information.
Local Area Network (LAN): A network which transports information between intelligent data and video devices within a single location or between buildings in a campus.
Local Loop: The connection from a subscriber to the central office. The portion of a circuit connecting the local exchange carrier's (LEC) central office with a customer's premise equipment across the local network.
Mean Time to Repair (MTTR): The average time it takes from issuing a trouble report to restoring service.
Mobile Communications: A wireless form of communication that emits, transmits and receives voice and data information via microwaves. Individuals can converse with one another and/or transmit and receive data while moving from place to place. Some examples include: cellular and digital cordless telephones; pagers; telephone answering devices; air-to-ground telecommunications; and satellite-based communications.
Modem: A device which enables data to be exchanged by converting signals. For example, a modem can be used to convert a digital signal to an analog signal to allow computers to transmit data, such as analog signals, over telephone lines.
Multimode Fibre: An optical fibre supporting propagation of multiple frequencies of light.
Multiplexing: A means of enabling multiple signals over a single channel.
Narrowband Network: A network capable of transmitting voice, video and data (e.g., telephone service, e-mail) at speeds up to 64 Kbps.
Network Layer: The layer that is responsible for routing, switching, and subnetwork access across the entire OSI environment.
Packet Switched Network: A communications network in which packets (messages) are individually routed between hosts, with no previously established communication path.
Packet Switching: A switching method whereby data is transmitted between terminals or computers in preaddressed "packets" of predetermined size. Since links are only busy during "packet" transmission, they are freed up to carry other packets attached to the same or other messages.
POP (Point of Presence): The physical access location interface between a local exchange carrier and an interexchange carrier fibre network. The point to which the telephone company terminates a subscriber's circuit for long distance service or leased line communications.
Port: An interface location on a computer or communications system that provides a point of access for peripheral equipment, such as printers, voice mail and CO lines.
PRI (Primary Rate Interface [ISDN]): An ISDN circuit transmitting at T-1(DS-1) speed (equivalent to 24 voice grade channels). One of the channels (D) is used for signaling, leaving 23 (B) channels to carry data and voice transmissions.
Private Branch Exchange (PBX): A user owned, customer-premise located telephone exchange that connects a customer location with the PSTN.
Protocol: A set of rules and procedures that permit the orderly exchange of information within and across a network.
Public Switched Telephone Network (PSTN): The regular telephone network, or any part of it. Along with telephone services, this network also carries data and other non-telephone services via conventional switched telephone circuits using regular telephone signaling.
Quality of Service: A measure of performance for a transmission system that reflects the quality and availability of service.
Remote Access Servers: A network computer that provides access to remote users via analog modem or ISDN connections. It includes the dial-up protocols and access control (authentication).
Router: A specialized switching device linking LANs and variously-located computers together into a seamless and more efficient corporate network despite, diverse communications protocols.
Server: A computer with software, data or certain peripherals, such as printers or scanners, shared among a group of users who are linked together in a network.
Single Mode Fibre: An optical fibre with a core diameter of less than 10 microns, used for high-speed transmission and long distances. It provides greater bandwidth than multimode fibre, but its smaller core makes it more difficult to couple the light source.
Structured Cabling: A systematic methodology for deploying reliable voice and data cabling within a building.
Synchronous: Transmissions of data at a fixed rate. Synchronous transmissions eliminate the need for start and stop bits because the receiver and transmitter work at the same speed.
System: A set of equipment or apparatus combined to perform a function within a carrier's telecommunications network (e.g., switching system).
TCP/IP (Transmission Control Protocol/Internet Protocol): The common name for the suite of protocols developed by the U.S. Department of Defense to support the construction of worldwide internetworks.
Telecommunications Infrastructure: Underlying facilities enabling a telecommunications network to transmit voice, video and data (e.g., cables, switching equipment and amplifiers).
Time Division Multiplexer: Multiplexing equipment that allocates trunk capacity over a single wire based on pre-assigned time slots.
Token Ring: A shared media link layer protocol for LAN connectivity. Defined by the IEEE 802.5 standard to run over various media at bit rates of 4 or 16 Mbps.
UTP (Unshielded Twisted Pair Cabling): Copper cabling designed to transmit data and voice traffic at frequencies up to 155 Mhz without external radio frequency shielding.
Web: A collection of servers linked together under the Internet HTTP protocol that offers users access to information in hypertext format. A Web server hosts one or more Web sites presenting information on, for example, an organization, an undertaking, an activity or an individual. Web sites are made up of HTML-programmed pages connected through hypertext links and containing text, images and multimedia components (i.e., sound, video, animation) or programmed modules.
Wideband Network: A network capable of transmitting less information (voice, data, images and video) than a broadband network but more than a narrowband network. Wideband networks can transmit data at speeds between 64 Kbps and 1.5 Mbps, or greater.
Wireless Service Providers: Companies that provide, under licence from Industry Canada, wireless telecommunications services to their customers. WSPs include Cellular, Personal Communications Services (PCS), Local Multipoint Communication Services (LMCS), public radio dispatch (SMR and ESMR) and satellite service.
World Wide Web (WWW): The hypertext presentation medium which delivers easy multimedia access to information residing on the Internet.
