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GlossaryA | B | C | D | E | F | G | H | I | L | M | N | O | P | R | S | T | U | V | W | X ADM - Add/Drop Multiplexer is capable of extracting or inserting lower-bit-rate signal from a higher-bit-rate multiplexed signal without completely demultiplexing the signal. API - Application Programming Interface is a software interface that enables applications to communicate with each other. An API is the set of programming language constructs or statements that can be coded in an application program to obtain the specific functions and services provided by an underlying operating system or service program. ADSL - Asymmetrical Digital Subscriber Line is a method to increase transmission speed in a copper cable. ASDL facilitates the division of capacity into a channel with higher speed to the subscriber, typically for video transmission, and a channel with significantly lower speed in the other direction. ATM - A technology for broadband transmission of high-capacity telecommunications signals. In addition to high capacity signal transmission, ATM provides considerable flexibility, since the individual subscriber is able to adapt the capacity of a switched connection to current requirements. Bandwidth - The information-carrying capacity of a communications channel. Usually expressed in Hertz (cycles per second) for analog circuits and in bits per second (bps) for digital circuits. Broadband Network - A network that enables a device to transmit a large amount of information (including voice, data and video) on the same cable over long distances. Cable - Physical transmission connection that is established between the two distinct nodes. It contains a number of strands, which are the physical conductors within the cable. A strand is either a fibre, a co-axial tube, or a copper wire, depending on the cable medium. In the case of a twisted pair cable, a single strand consists of two copper wires twisted together. Capacity - Measure of signal rate through a connection or trail. Usually expressed in Gb/sec, Mb/sec or Kb/sec. Carrier class - Carrier class refers to products designed specifically to meet the capacity, performance scalability, availability and network management requirements of network service providers. Circuit - Trail that is allocated to a customer. Circuit Switching - A switching system that establishes a dedicated physical communications connection between end points, through the network, for the duration of the communications session. Client layer - The network layer which uses capacity provided by another layer, called the server layer. CORBA - Common Object Request Broker Architecture is an architecture that enables pieces of programs, called objects to communicate with one another regardless of what programming language they were written in or what operating system they're running on. An industry consortium known as the Object Management Group developed CORBA. Coverage - The geographical reach of a mobile phone network or system. DDF - Digital Distribution Frame is a frame at which interconnections are made between the digital output of some equipment and the digital input of other equipment.
Digital - Where information - speech, for example- is encoded before transmission. Digital networks are rapidly replacing analog ones as they offer improved sound quality, secure transmission and can handle data as well as voice. DWDM - Dense Wave Division Multiplexing is an optical (analog) multiplexing technique used to increase the carrying capacity of a fibre network beyond what can currently be accomplished by time division multiplexing (TDM) techniques. Different wavelengths of light are used to transmit multiple streams of information along a single fibre with minimal interference. DXC - Digital Cross Connect Point of flexibility where one connection is connected to another connection or to a trail termination function. A digital cross connect is a software configurable piece of equipment that can provide several such points of flexibility. ETSI - The European Telecommunications Standardisation Institute, which is the European standardisation body for telecommunications. Fibre - The structure that guides light in a fibre optic system. Frame - Equipment is usually connected to other equipment through a frame. When two pieces of equipment are connected through a frame, they are said to be strapped together. The wire that connects them is referred to as a strap. GUI - Graphical User Interface is the graphical user interface, or GUI, provides the user with a method of interacting with the computer and its special applications, usually via a mouse or other selection device. The GUI usually includes such things as windows, an intuitive method of manipulating directories and files, and icons. Hub - Any intermediary node that lies on the path of a trail that spans more than two nodes. It is a point on the trail where the higher order trail that supports it is switched, usually involving adaptation between levels. IP - The Internet Protocol defines how information travels between systems across the Internet. IPVPN - The Internet Protocol Virtual Private Network is a way of using a public network (typically the Internet) to link two sites of an organisation. A VPN is typically set up by protecting the privacy and integrity of the communication line using a secret session key. ISDN - Integrated Services Digital Network, which is a technology that is offered by the telephone carriers of the world. ISDN combines voice and digital network services in a single medium making it possible to offer customers digital data services as well as voice connections through a single "wire" (copper pair). LAN - Local Area Network which is a high-speed local computer communications system. LANs allow file and device sharing within geographically adjacent workgroups - computers and shared devices connected to the same network medium in a limited area, usually within a single building or a computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a wide-area network (WAN). Most LANs connect workstations and personal computers. Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it is also able to access data and devices anywhere on the LAN. This means that many users can share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail. LTE - Line Terminal Equipment Function to take the output from a multiplexer and convert it into a form suitable for long distance transmission, or to convert a long distance signal into a form that can be fed back into a multiplexer. The type of LTE used depends on the media employed for the transmission. MDF - Main Distribution Frame is a frame at which interconnections are made between the transmission network and the copper system. Multiplexer - Equipment that combines several distinct aggregate signals to form one aggregate signal. Some multiplexers can also perform the inverse function of splitting an aggregate signal into its component parts. A multiplexer is a rate adaptation device. NIS - Network Information System. Node - Grouping of transmission equipment used for administration purposes. It is installed in a physical place, a location. Nodes are uniquely identified within a particular location. Operator - Company that operates a telephone network, for example AT&T and BT. ODF - Optical Distribution Frame is a frame at which interconnections are made between an optical fibre cable and the appropriate LTE. Optical Network - The optical network will provide all basic network requirements in the optical layer; namely capacity, scalability, reliability, survivability, and manageability. Today, the wavelength is the fundamental object of the optical network. Currently, basic network requirements can be met through a combination of the optical transport layer (DWDM today), that provides scalability and capacity beyond 10 Gbps, and the SONET/SDH transport layer, which provides the reliability, survivability, and manageability needed for public networks. The long-term vision of an "all optical network" is of a transparent optical network where signals are never converted to the electrical domain between network ingress and egress. The more practical implementation for the near term will be of an opaque optical network, i.e. one that works to minimize but still includes optical/electrical/optical conversion. Optical network elements will include terminals, dynamic add/drop multiplexers, and dynamic optical cross-connects. ORB - The Object Request Broker is a component in the CORBA programming model that acts as the middleware between clients and servers. In the CORBA model a client can request a service without knowing anything about what servers are attached to the network. The various ORBs receive the requests, forward them to the appropriate servers, then hand the results back to the client. Packet Switching - A method of switching data in a network where individual packets of a set size and format are accepted by the network and delivered to their destinations. The sequence of the packets is maintained and the destination established by the exchange of control information (also contained in the packets) between the sending terminal and the network before the transmission starts. PDH - Plesiochronous Digital Hierarchy. PSTN - Public Switched Telecom Network. Router - A data switch that handles connections between different networks. A router identifies the addresses on data passing through the switch, determines which route the transmission should take and collects data in so-called packets, which are then sent to their destinations. Routing - The forwarding of data packets in packet-switched networks, to the intended address. SDH - Synchronous Digital Hierarchy is a standard for digital signal transmission within transport networks. SDH - Synchronous Digital Hierarchy is the international standard for transmitting digital information over optical networks. Term used by ITU to refer to SONET. Sonet - Synchronous Optical Network is the standard for transmitting digital information over optical networks. Fibre optic transmission rates range from 51.84 Mbps to 9.95 Gbps. It defines a physical interface, optical line rates known as Optical Carrier (OC) signals, frame formats and a OAM&P (Operations, Administration, Maintenance and Provisioning) protocol. The base rate is known as OC-1 and runs at 51.84 Mbps. Higher rates are a multiple of this such that OC-12 is equal to 622 Mbps (12 times 51.84 Mbps). TE - Terminal Equipment Generic is the term applied to equipment, which terminated a transmission trail resulting in a circuit. Terminal equipment covers equipment such as: ¨ Subscriber Terminal Equipment (phones, faxes, and so on) TMN - Telecommunications Management Network TNAS - AlTion's Network Information System (NIS) called Transport Network Administration System (TNAS) provides a central register of all network connectivity and all equipment and facilities necessary to support these connections. TNAS is applicable to core and access transport networks. TNAS can be applied to Fixed, Mobile, National, International and Metropolitan networks. Unix - An OS (operating system) originally developed by AT&T which, in various incarnations, is now available on most types of supercomputer. VOIP - A technology for transmitting ordinary telephone calls over the Internet using packet-linked routes. Also called IP telephony. WDM - Wavelength Division Multiplexing is a new technology that uses optical signals on different wavelengths to increase the capacity of fibre optic networks in order to handle a number of services simultaneously. Work Order - Formatted technical instructions that requests network personnel to connect (or disconnect) equipment to (or from) each other. XDSL - A shorthand term used for ADSL, Asymmetric Digital Subscriber Line, and HDSL, High-Speed Digital Subscriber Line. ADSL and HDSL are Access Network transport technologies expected to be deployed for specific high-speed services in the coming years. |
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