A
A-D ConversionAnalog-to-digital conversion. A-D conversion is a process in which an analog signal is modified into a digital signal. A-D conversion takes place, for example, when an analog modem call reaches a digital modem.
AAA
Authentication, authorization, and accounting. A remote access security approach that controls network access by requiring user identification and restricting access to only particular resources, and maintains records of use for billing and network audit.
A
Alternating Current
ACR
Abandon Call and Retry
ADSL (Asymmetric Digital Subscriber Line)
A modem technology for transmitting information at high speeds on existing copper phone lines to homes and businesses. It's so named because most of the channel sends information downstream to the user (at speeds ranging from 1.5 Mb/s to 9 Mb/s); the rest of the channel carries information upstream from the user (at speeds ranging from 16 kb/s to 640 kb/s.)
AIS
Alarm Indication Signal. An Unframed All Ones Pattern
ALT (Automated Loop Test System)
The operations system that provides a single comprehensive automated test system for testing international customer POTS lines.
ALU
Average Line Utilization
AM
Amplitude Modulation.
AMI
Alternate Mark Inversion. A line encoding scheme for transmitting data bits over T1 transmission systems.
AMPS
Advanced Mobile Phone Service: the original name for cellular phone service, developed by Bell Labs and launched in Chicago, 1978. It still designates analog cellular phone service.
AND Logic Gate
A type of logic gate whose output considers the first and second signals inputted into it.
See for more info.
ANI
Automatic Number Identification is also known as CLID. ANI is a mechanism that informs the called party of the phone number identification of the calling party. Though ANI is thought of as an ISDN feature, it is actually distinct from ISDN, and is a part of Signaling System 7.
APP
Ascend Password Protocol
APP server
The APP Server utility lets users respond to token password challenges received from a remote network access server (NAS). Network access servers offer a complex security algorithm that forces a user to have possession of a security card that can generate a password. When a user on the LAN starts an application that requires a connection to a host on a secure network, the terminal server initiates the call, and after the initial session negotiation, the remote NAS returns a password challenge. The user has 60 seconds to obtain and enter the current dynamic password from the security card.
ARP
Address Resolution Protocol. This portion of the TCP/IP protocol maps an IP address to the physical address (Ethernet Address) of the PC that it is on, helping to identify PCs on an Ethernet LAN. See also Ethernet, TCP/IP, and proxy ARP.
ASCII Mode
A Telnet mode for terminal-server users. In ASCII mode, bit 8 is set to 0 (zero). ASCII mode is also called standard 7-bit mode or network virtual terminal (NVT) ASCII. This mode is the default if no other mode is specified. Compare with binary mode, transparent mode.
ASCII Text File
A file that contains only letters, numbers, and punctuation symbols. An ASCII text file cannot include hidden text-formatting codes.
ASN.1
Abstract Syntax Notation One
AT&T
American Telephone and Telegraph
ATM
See Asynchronous Transfer Mode.
ATM Adaptation Layer (AAL)
The AAL enables engineers to adapt the asynchronous transfer mode (ATM) layer to particular services. Lies between the ATM layer and the higher layers and maps or adapts the functions or services of the higher layers onto a common ATM bearer service.
ATM Layer
The core layer of the asynchronous transfer mode (ATM) standard. The ATM layer routes the cells across the network, performing both multiplexing and demultiplexing functions.
ATMP
Ascend Tunnel Management Protocol. A virtual private networking protocol. Virtual private networks provide low-cost remote access to private LANs via the Internet. The tunnel to the private corporate network may be from an ISP, enabling mobile nodes to dial-in to a corporate network, or between two corporate networks that use a low-cost Internet connection to access each other.
An ATMP session occurs between two MAX units, or a MAX and Pipeline 50 or 130 (which can act as a home agent, described below) via UDP/IP. All packets passing through the tunnel are encapsulated in standard GRE (Generic Routing Encapsulation) as described in RFC 1701. ATMP creates and tears down a cross-Internet tunnel between the two MAX units. In effect, the tunnel collapses the Internet cloud and provides what looks like direct access to a home network. Bridging is not supported through the tunnels. All packets must be routed using IP or IPX.
One ATMP units acts as a foreign agent (typically a local ISP) and one as a home agent (which can access the home network). A mobile node dials into the foreign agent, which establishes a cross-Internet IP connection to the home agent. The foreign agent then requests an ATMP tunnel on top of the IP connection. The foreign agent must use RADIUS to authenticate mobile nodes dial-ins.
The home agent is the terminating part of the tunnel, where most of the ATMP intelligence takes place. It must be able to communicate with the home network (the destination network for mobile nodes) through a direct connection, another router, or across a nailed connection.
AUI
Autonomous Unit Interface or Auxiliary Unit Interface This refers to the 15-pin D connector and cables that connect single and multiple channel equipment in an Ethernet transceiver.
Abort Error
An error indicating an attempted and failed connection.
Absolute Congestion
In a frame relay network, a congested condition that occurs when the queue length reaches a third threshold (64 buffers full) and no room remains in the queue. When the average queue length (AQL) exceeds the threshold for absolute congestion, all incoming frames are discarded, and the forward explicit congestion notification (FECN) and backward explicit congestion notification (BECN) bits are set. Compare with mild congestion, severe congestion.
Abstract Syntax Notation One (ASN.1)
Abstract Syntax Notation One.
Access Bandwidth
The ability of a communications network to provide bandwidth dynamically so users will receive service regardless of the bandwidth their service request requires.
Access Concentrator
A device that efficiently forwards data, handling incoming calls for a network point of presence (POP). In general, an access concentrator supports dial-in modem calls, ISDN connections, nailed-up links, frame relay traffic, and multiprotocol routing.
Access Control
The management of permissions and restrictions for logging onto a computer or network. Systems typically employ individual profiles that specify which network-attached resources are available to which users. The profiles are maintained in a database, such as RADIUS.
Access Rate
The data rate of the user access channel.
Access Router
An access device with built-in basic routing protocol support, specifically designed to allow remote LAN access to corporate backbone networks. Not designed to replace backbone routers or to build backbone networks.
Access Server
Same as remote access server (RAS). Any devise that enables multiple remote users to access a network. Lucent's PortMaster 2 and PortMaster 3 products are remote access servers.
Active Hub
A device that amplifies transmission signals on a network, enabling them to be transmitted over a much greater distances than is possible with a passive hub.
Active Open
A client-initiated operation that enables a device to establish a TCP link with a server at a fixed IP address.
Adaptive Differential Pulse Code Modulation (ADPCM)
A standard that codes for digitized speech. It samples the sound waves 8,000 times a second; the sample representing the difference between two adjacent samples.
Address
A number used to identify a computer or other device on a network or internetwork.
Address Mask
A bit mask used to select bits from an Internet address for subnet address.
Address Resolution
A method for translating one type of address into another - for example, an Internet Protocol address into a media access control (MAC) address.
Address Resolution Protocol (ARP)
This portion of the TCP/IP protocol maps an IP address to the physical address (Ethernet address) of the PC that it is on, helping to identify PCs on an Ethernet LAN.
Adjacency
A relationship between two routers on the same physical network or between the endpoints of a virtual link that controls the distribution of routing protocol packets by limiting their exchange to those routers or endpoints.
Adjunct Processor
A computer outside a telephone switching system that "talks" to the switch and gives it switching commands.
Administration Tool
A system administration utility, such as Solaris, that enables a system administrator to maintain and monitor system databases, files, printers, user accounts, and hosts.
Advanced Intelligent Network
A switched voice and data network consisting of a variety of network elements. It refers to open interfaced, multi-vendor,telecommunications capabilities that let phone companies create and customize their service offerings.
Advanced Network Services
The name given to Lucent Technologies' Intelligent Network servers and services software that help enable network operators, information and service providers to deliver services to end customers.
Advanced Services Platform (ASP)
The software of the 5ESS®-2000 Switch that recognizes call triggers and queries to the intelligent network.
Agent
A software program installed in a managed network device. An agent stores management information and responds to the manager's request for this information.
Aggregation
The process of combining multiple prefixes from one or several routes so that a single prefix and route can be advertised. See also summarization.
Alarm Indication Signal (AIS)
An AIS is a signal that a device sends in order to take a T1 line, DS3 line, or DS2 stream out of service.
Alarms
Red, yellow, and blue. In T1, a red alarm is generated when a locally detected failure, such as loss of synchronization, exists for 2.5 seconds causing a carrier group alarm (CGA). A yellow alarm is a T1 alarm signal sent back to the source of a failed transmit circuit in a DS-1, two-way transmission path. In T1, the blue alarm is turned on when two consecutive frames have fewer than three zeros in the data bit stream. Also known as the alarm indication signal (AIS).
Alternative Operator Services
Business not associated with the telephone company that provides operator services, for example, to private pay phone companies.
American National Standards Institute (ANSI)
ANSI creates standards for networking and communications. It is the U.S. representative to the International Standards Organization (ISO).
American Standard Code For Information Interchange (ASCII)
ASCII is a character-encoding system for local area networks (LANs). The 128 standard ASCII characters are composed of seven bits, and have the values 0–127. The extended ASCII character set contains another 128 values.
Amplification
Strengthening of a signal by an electrical device.
Amplitude Modulation (AM)
A transmission technique that inserts information onto an electrical carrier wave by varying the amplitude of the carrier.
Analog
A type of signal that represents information as a continuously varying voltage, current, or intensity level. Analog transmission is typically used for video and POTS (plain old telephony service).
Analog Data
Data that can have any value in a range and that can change continuously; the time of day represented by clock hands, or the temperature represented by a liquid thermometer are examples of analog data.
Analog Display Services Interface (ADSI)
A protocol that allows text messages generated by a remote computer or central office switch to be displayed on a user's telephone or TV set.
Analog Line
A line that transmits data by means of an analog signal.
Analog Loopback
A test that checks whether the modem or data terminal equipment (DTE) is causing errors in data transmission. During an analog loopback, the system sends data between the local modem and the local DTE. Errors in transmission indicate a problem with the modem, DTE, or the interface between them.
Analog Signal
A type of signal that encodes data transmitted over wire or through the air, and is commonly represented as an oscillating wave. An analog signal can take any value in a range, and changes smoothly between values. An analog signal can transmit analog or digital data. For example, a radio station sends analog music data using analog signals, while a modem transmits digital data using analog signals.
Analog Technology
Technology that uses a stream of continuously changing electrical waves to carry voice or low-speed data.
Answer Number
A phone number used for call-routing purposes. It indicates "route calls received on this number to me
AppleTalk
Apple Computer's proprietary local area network for linking Apple computers and peripherals.
AppleTalk Control Protocol (ATCP)
A protocol that enables you to route AppleTalk packets that are encapsulated in Point-to-Point Protocol (PPP).
AppleTalk Remote Access (ARA)
ARA enables a remote Macintosh workstation to gain access to an IP network. You can use ARA over a modem or V.120 connection. You can also use synchronous PPP when the calling unit is an AppleTalk-enabled Lucent unit. A client can dial in using ARA client software or a PPP dialer that supports AppleTalk.
AppleTalk Remote Access Protocol (ARAP)
AppleTalk Remote Access Protocol.
AppleTalk Routing
A routing configuration in which Macintosh computers can share files and services on a network. A Lucent unit configured for AppleTalk routing can receive dial-in connections from AppleTalk Remote Access (ARA) client software, Point-to-Point Protocol (PPP) dial-in software that supports AppleTalk, and AppleTalk-enabled Lucent units.
Applet
A small software module that runs on a Java Virtual Machine (JVM) inside a Web browser.
Appletalk Call Filter
An Appletalk call filter can instruct the Pipeline to place a call and reset the Idle Timer based on Appletalk activity on the LAN, and can prevent inbound packets or Appletalk Echo (AEP) packets from resetting the idle timer or initiating a call.
Application
Functional system made up of software, hardware, or combination of both, that performs some useful task. Database managers, spreadsheets, word processors, videoconferencing systems, LANs, fax machines, etc., are examples of applications.
Application Layer
The highest layer of the OSI Reference Model. The application layer provides applications with access to the network. File transfer, email, and network management software are examples of Application-layer programs. Protocols such as File Transfer Protocol (FTP), Rlogin, Simple Network Management Protocol (SNMP), and Telnet provide application-layer services.
Application Programming Interface (API)
A set of software commands that can be used by an application program to communicate with the operating system or other system program such as a database management system.
Application Specific Integrated Circuit (ASIC)
An integrated circuit which has been built for a specific application. Manufacturers use it to consolidate many chips into a single package, reducing system board size and power consumption.
Archie
Archie. An Internet utility for finding files stored on anonymous FTP sites. To find a file with Archie, you must know the exact filename or a substring of it. See also FTP.
Area
A contiguous collection of networks and hosts. Each area runs a separate copy of the shortest-path-first algorithm and has its own topological database.
Area Number
A portion of a switched multimegabit data service (SMDS) address, or a number denoting an Open Shortest Path First (OSPF) area. In an SMDS address, the area number can be four bytes long, and is sometimes referred to as an area ID. An OSPF area number is expressed in dotted decimal notation, but it is not an IP address.
Area border router
A router that attaches to the backbone and one other area. It runs separate copies of the shortest-path-first algorithm for each area it attaches to.
Ascend Inverse Multiplexing Protocol (AIM)
An in-band protocol used to manage the interconnection of two remotely located inverse multiplexers. AIM is a feature-rich, widely used inverse multiplexing protocol developed and supported by Ascend Communications.
Ascend MAX
See MAX.
Ascend Multiband
See Multiband.
Ascend Pipeline
See Pipeline.
Assembly
In the chip making world, the process of enclosing a device in a plastic or ceramic package.
Assembly Language
A symbolic language that is converted by a computer into executable machine-language programs. Assembly language is easier to manipulate and remember than machine language.
Asymmetric Digital Subscriber Line (ADSL)
A technology that allows more data to be sent over existing copper telephone lines (POTS). ADSL supports data rates from 1.5 to 9 Mbps when receiving data (known as the downstream rate) and from 16 kbps to 640 Kbps when sending data (known as the upstream rate). ADSL can use either carrierless amplitude phase (CAP) modulation or discreet multi-tone (DMT) modulation.
Asynchronous Communications Server
A LAN server that enables a network user to dial out of the network and into the public switched telephone network (PSTN), or to access nailed-up lines for asynchronous communications. An asynchronous communications server is also called a dial-in/dial-out server or a modem server.
Asynchronous PPP
One of the modes in which the point-to-point protocol is utilized. Asynchronous means that the characters which form data packets are sent at irregular intervals. There is no clocking signal to time transmission. Asynchronous PPP is commonly used in lower-speed transmission and less-expensive transmission systems
Asynchronous Transfer Mode (ATM)
A high bandwidth, controlled-delay fixed-size packet switching and transmission system. Uses fixed-size packets also known as "cells"; ATM is often referred to as "cell relay." ATM will provide the basis for future broadband ISDN standards.
Asynchronous Transmission
A mode in which the sending and receiving serial hosts know where a character begins and ends because each byte is framed with additional bits, called a start bit and a stop bit. A start bit indicates the beginning of a new character; it is always 0 (zero). A stop bit marks the end of the character. It appears after the parity bit, if one is in use.
Attenuation
The reduction in the strength of a signal over distance, expressed in decibels per kilometer (dB/Km) or per 100 feet. Factors affecting attenuation are the frequency range of the signal, wire shielding, and type of cable. Unshielded twisted pair (UTP) cable suffers from the most attenuation, while fiber-optic cable has very little attenuation.
Attribute Design Database System (ADDS)
The operations system of a network that manages the physical inventory, automates service/transport provisioning, and tracks orders.
Authentication
Authentication is a procedure that establishes the legitimacy of users and defines the parameters of the sessions they establish. As such, authentication can be thought of as a security measure that controls and defines network access. It is always the first part of a session; the range of authentication parameters that can be set depend upon the specific authentication system employed.
Authentication Header (AH)
A provision of IPSec that adds a "digital signature" to an IP packet. The digital signature is created through a key-controlled hashing of each packet, and provides both authentication and integrity.
Authority Zone
A part of the domain name hierarchy for which a single name server is the authority.
Authorization
Grants individual authenticated users access to network-attached resources. Such permission to access resources is typically managed with an access control database, and can be enforced either in network access equipment or a firewall.
Auto-reconnect
An automatic reconnection of a link that has been lost. The software used to manage the connection notes the lost connection and re-establishes it.
Autobaud
A method of training up to a set modem data rate. If a DSL modem cannot train to this data rate, it will connect at the closest rate to which it can train (the modem’s ceiling rate).
Automated Provisioning
Also known as Self Provisioning or Dynamic Provisioning, this is a dynamic network's Automatic Call Distributor; an intelligent network application that accepts incoming calls and distributes them in a predetermined manner to an appropriate station.
Automatic Call Distributor (ACD)
The technology provided by stand-alone equipment, an add-on feature to a telephone system, or software that automatically manages and controls incoming calls.
Automatic Location Identification (ALI)
A network feature that works with Automatic Number Identification. A database associates a physical location with a telephone number.
Automatic Number Identification (ANI)
A network feature that sends a calling party's telephone number to the called party. Popularly known as Caller ID.
Automatic Protection Switching
The ability of transmission equipment to recover from failures such as a cable cut.
Autonomous System (AS)
An AS is a group of Open Shortest Path First (OSPF) routers that exchange information, typically under the control of one company. An AS can include a large number of networks, all of which share the same AS number. All information exchanged within the AS is interior. Exterior protocols, such as Exterior Gateway Protocol (EGP), exchange routing information between one AS and another. Using an EGP, a Lucent unit imports external routes into its OSPF database and flags them as ASE (autonomous system external).
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