Glossary-E
A Data Communication Historical Series
By Bob Pollard

HOME                      INDEX

E&M:
Receive and Transmit: Ear and Mouth: A type of signaling traditionally used in the telecommunications industry. Indicates the use of a handset that corresponds to the ear (receiving) and mouth (transmitting) component of a telephone.

E&M SIGNALING:

Method of signaling on a DS0 timeslot; the signaling bits are used to indicate call states, such as on-hook, off-hook, alerting, and dial pulsing.

E CHANNEL:

Echo Channel:  64-kbps ISDN circuit-switching control channel. The E channel was defined in the 1984 ITU-T ISDN specification but was dropped in the 1988 specification.

E.164:

1) ITU-T recommendation for international telecommunication numbering, especially in ISDN, BISDN, and SMDS.

2) Name of the field in an ATM address that contains numbers in E.164 format.

E1:

The European standard for high-speed digital transmission: 2.048Mbps. The E1 has 31 available 64k channels for use.

E1 (CEPT T1):

Provides for transfer rates up to 2.048 Mbps in the European digital transmission hierarchy as defined by CEPT; TS0 is used for framing and maintenance; TS16 is optionally used for signaling; TS1 is assigned as channel one.

E2A:

Legacy protocols for providing OAM&P functions between a network element and an operations support system.

E3:

A digital circuit with standardized characteristics operating at 34.368 Mbps; this standard is widely used in Europe for inter-carrier communications as an equivalent of a DS-3. Japans third E3 operates at 32.064 Mbps.

EAM CARD:

Electronic Accounting Machine – See IBM card

EAP:

Extensible Authentication Protocol: Framework that supports multiple optional authentication mechanisms for PPP, including clear text passwords, challenge-response, and arbitrary dialog sequences.

EARLY TOKEN RELEASE:

Technique used in Token Ring networks that allows a station to release a new token onto the ring immediately after transmitting instead of waiting for the first frame to return. This allows for two tokens to exist on the network simultaneously. Early token release takes advantage of the idle time created by regular token release during heavy traffic periods.

This feature can increase the total bandwidth on the ring.

EARN:

European Academic Research Network: European network connecting universities and research institutes. EARN merged with RARE to form TERENA.

EARTH STATION (Ground Station):

Refers to the transceiver (transmitter/receiver) and antenna located on earth for communication with a satellite

EAS:

1) Expert Agent Selection: A Mode in the Lucent Definity ECS ACD. In this mode, agents are added automatically to pre-assigned skill groups at login. Calls can be routed either to the agent's physical extension or to the agent's login ID. In non-EAS mode, agents must add themselves manually to hunt groups and calls can be routed only to physical extensions.

2) See Extended Area Service

EBCDIC:

Extended Binary Coded Decimal Interchange Code: Also may be referred to as the Paper Tape Transmission Code (PTTC). A 6-bit, plus parity bit code set. Uses upper and lower case similar to the Baudot code set.

EBONE:

European Backbone: Pan-European network backbone service

EBU:

European Broadcasting Union: Founded in 1950 and headquartered in Geneva, the European Broadcasting Union is an association of national broadcasters that negotiates broadcasting rights for major sports events, operates the Euro-vision and Euro-radio networks, organizes program exchanges, stimulates and coordinates co- productions, and provides operational, commercial, technical, legal, and strategic services.

ECC:

1) Error-Correcting Code: An error-detecting code that incorporates additional signaling elements (bits/characters) enabling errors to be detected and corrected at the receiving end.

2) Established Common Carrier

ECDSA:

Elliptic Curve Digital Signature Algorithm: Standard [A9062] that is the elliptic curve cryptography analog of the Digital Signature Algorithm.

ECHO:

1) A signal that has been reflected or otherwise returned with sufficient magnitude and delay to be perceived by the sender.

2) Telephony-Audible and unwanted leak-through of a persons own voice into that persons receive (return) path. Hence signal from the transmission path is returning to one's ear through the receive path. Telephone Companies install Echo suppressers on the telephone channel.

3) Also used to describe when a receiving terminal program sends back (echo) the characters as they are received for error checking purposes.

ECHO CANCELER:

A device to suppress echo’s (similar to an echo suppressor) without speech clipping and able to operate during two-way transmissions.

ECHO CANCELLATION:

A technique that filters out and isolates unwanted signals caused by echoes from the main transmitted data or voice signal

ECHO CHECK:

A form of error checks where the received data is returned to the sender for comparison with the original transmitted data.

ECHO DISTORTION:

A problem encountered on telephone lines caused by electrical reflections (echo) of the original analog (voice) signal, many times caused by an impedance mismatch.

ECHO FREE SECONDS:

See EFS

ECHO-PLEX:

1) A communication procedure where characters input from the keyboard does not print directly (immediately) on the associated printer. The keyboard input is sent to a computer, which echoes the characters back for printing. This requires full duplex operation and is a form of error control since the operator has confirmation the characters are received by the computer.

2) Mode in which keyboard characters are echoed on a terminal screen upon return of a signal from the other end of the line indicating that the characters were received correctly.

ECHO SUPPRESSER / ECHO CANCELLER:

A device used to block any information or voice on the receiving line when the transmitting side is in use. Echo Suppressers are used by the Telephone Company to suppress positive feedback (singing) on the telephone network. A MODEM deactivates these devices by sending the 2100 Hz answer tone with 180 phase reversals every 450msec at the beginning of the connection.

ECHOPLEX / ECHOPLEXING:

A communications procedure where the typed characters sent to a computer on a full-duplex facility are echoed (sent) back to the sender. This allows the sender to ensure that the data was correctly received.

ECM:

Error Correction Mode: An option defined in T.30 and available in many fax machines that allows a fax page to be broken into HDLC-like frames, which allow transmission errors to be detected.

ECM DISABLE:

Feature that disables the ECM capability in a fax DIS signal

ECMA:

European Computer Manufacturers Association: A trade organization that issues data communications standards and is a member of the International Standards Organization (ISO).

EDC:

Error Detecting Code: A code in which each telegraph or data signal conforms to specific rules of construction. Departures from this construction in the received signals can automatically be detected. These codes require more signal elements than are necessary to convey the basic information.

EDFA:

Erbium-Doped Fiber Amplifier: Optical fibers doped with the rare earth element erbium can amplify light in the 1550 nm (nanometer) region when pumped by an external light source.

EDGE:

Enhanced Data for GSM Evolution: A further development of the GSM (Global Standard for Mobile) protocol designed to handle data at speeds up to 384 Kbps. Considered to be 3G wireless technology.

EDGE DEVICE:

1) Physical device that is capable of forwarding packets between legacy interfaces (Ethernet and Token Ring) and ATM interfaces based on data-link and network layer information. An edge device does not participate in the running of any network layer routing protocol but it obtains forwarding descriptions using the route distribution protocol

2) Any device that is not an ATM switch that can connect to an ATM switch.

EDGE LSR:

Edge Label Switch Router: The role of an Edge LSR is to turn unlabeled packets into labeled packets, and vice versa.

EDI:

Electronic Data Interchange: An industry standard (ANSI X12, X.400) for direct computer-to-computer information exchange.

EDIFACT:

Electronic Data Interchange for Administration, Commerce, and Transport: Data exchange standard administered by the United Nations for a multi-industry EDI standard.

EDITS:

Electronic Data Information Technical Service: The collection of repair data and failure information, which is analyzed to determine problem areas. Pertinent information is forwarded to the switching centers and field offices.

EECM:

End-to-End Call Manager

EEPROM:

Electrically Erasable Programmable Read Only Memory: With a normal ROM the chip(s) must be replaced when new BIOS instructions are introduced. With an EEPROM a program can cause the chips controller to simulate a non-programmed mode and then new BIOS code can be downloaded into the chip. This allows BIOS updates to be provided via a floppy disk.

EFCI:

Explicit Forward Congestion Indication: In ATM, one of the congestion feedback modes allowed by ABR service. A network element in an impending congestion state or in a congested state can set the EFCI. The destination end-system can implement a protocol that adaptively lowers the cell rate of the connection based on the value of the EFCI.

EFF:

Electronic Frontier Foundation: Foundation established to address social and legal issues arising from the impact on society from the increasing use of computers as a means to communicate and distribute information.

EFFECTIVE RATE TRANSFER:

The bit/byte rate at which data can be sent after accounting for data compression

EFI:

See Extensible Firmware Interface

EFI SYSTEM PARTITION:

On Itanium-based computers, a portion on a GUID Partition Table (GPT) disk that is formatted with the FAT (File Allocation Table) file system and contains the files necessary to start the computer. Every Itanium-based computer must have at least one GPT disk with an EFI system partition. The EFI system partition serves the same purpose as the system volume found on x86-based computers.

EFS:

Echo Free Seconds: A time percentage measurement, in seconds, of the time data is transmitted error free. See Echo Distortion

EGP:

External Gateway protocol: Used by communication gateways in different autonomous systems. EGP allows gateways to share routing information.

EGRESS:

Traffic leaving the network

EHF:

Extremely High Frequency: The band of frequencies between 30,000 and 300,000 megahertz

EHSA:

Enhanced High System Availability: Processor redundancy scheme that reduces switchover time by requiring that the redundant processor be running in a hot standby mode.

EIA:

Electronic Industries Association: A Group that specifies electrical transmission standards

EIA-530

Two electrical implementations: EIA/TIA-449: RS-422 for balanced transmission and RS-423 for unbalanced transmission.

EIA INTERFACE:

Electronic Industries Association Interface: A Data transmission standard, which includes transmission duration, and hardware (devices) current and voltage levels.

EIA/TIA:

Electronics Industries Association and Telecommunications Industries Association: The merged combination of the U S Electronics Industries Association and the Telecommunications Industries Association. The EIA is a U S trade organization for the electronics industry that concentrates on hardware interface standards, such as the RS232C and RS422 standards, that specify the electrical characteristics of interconnections between terminals and computers or between two computers.

EIA/TIA-232:

Common physical layer interface standard, developed by EIA and TIA: Supports unbalanced circuits at signal speeds of up to 64 kbps. Closely resembles the V.24 specification; formerly called RS-232.

EIA/TIA-449:

Popular physical layer interface developed by EIA and TIA: Essentially, a faster (up to 2 Mbps) version of EIA/TIA-232 capable of longer cable runs; formerly called RS-449.

EIA/TIA-586

Standard that describes the characteristics and applications for various grades of UTP cabling.

EICAR:

European Institute of Computer Anti-Virus Research: In conjunction with several anti-virus software companies, EICAR has developed a test file for anti-virus software.

EICAR:

Standard Anti-Virus Test File: This text file consists of one line of printable characters; if saved as EICAR.COM, it can be executed and will display the message: EICAR-STANDARD-ANTIVIRUS-TEST-FILE. This provides a safe and simple way of testing the installation and behavior of anti-virus software without using a real virus.

EIGRP:

Enhanced Interior Gateway Routing Protocol: Advanced version of IGRP developed by Cisco. Provides superior convergence properties and operating efficiency, and combines the advantages of link state protocols with those of distance vector protocols.

E-INFOSTRUCTURE:

A shared foundation of technologies, tools, services, and intellectual input that enables an uninterrupted flow of information

EIP:

Ethernet Interface Processor: Interface processor card on the Cisco 7000 series routers. The EIP provides high-speed (10-Mbps) AUI ports that support Ethernet Version 1 and Ethernet Version 2 or IEEE 802.3 interfaces, and a high-speed data path to other interface processors.

EIRP:

Effective Isotropic Radiated Power: Term for the performance of an antenna in a given direction relative to the performance of a theoretical (isotropic) antenna; expressed in watts or dBW.

EIRP is the sum of the power sent to the antenna plus antenna gain.

EISA:

Extended Industry-Standard Architecture: 32-bit bus interface used in PC(s), PC-based servers, and some UNIX workstations and servers

E-ISUP:

Extended-ISUP (ISDN User Part: Originally a subset of Q.761 ISUP. It is expanding in to a superset of ITU and ANSI ISUP. In addition, it supports the delivery of SDP parameters via generic digits. E-ISUP uses Internet Protocol (IP) and therefore uses IP addresses instead of point codes. ISDN = Integrated Services Digital Network

ELAN:

Emulated LAN (Local Area Network): ATM network in which an Ethernet or Token Ring LAN is emulated using a client-server model. ELAN(s) are composed of a LEC, LES, BUS, and a LECS. Multiple ELAN(s) can exist simultaneously on a single ATM network. ELAN(s) are defined by the LANE specification.

ELAP:

Ether-Talk Link Access Protocol: Link-access protocol used in an Ether-Talk network. ELAP is built on top of the standard Ethernet data link layer.

ELECTROMAGNETIC:

Refers to the combined electrical and magnetic fields that are created by electrons moving through a conductor

ELECTROMAGNETIC FIELD:

Refers to a rapidly moving electric field and its associated moving magnetic field, which is at right angles both to the electric lines of force and to their direction of motion.

ELECTROMAGNETIC INTERFERENCE:

See EMI

ELECTROMAGNETIC SPECTRUM:

Full range of an electromagnetic (magnetic) frequencies used in commercial RF systems. Commercial RF systems typically are classified in ranges that include MF, HF, VHF, SHF, and EHF. Military systems may include frequencies outside these ranges.

ELECTROMOTIVE FORCE (EMF):

The voltage or pressure that causes current to flow in a circuit

ELECTRONIC INDUSTRIES ASSOCIATION INTERFACE:

See EIA

ELECTRONIC JOURNAL:

A periodical that is published online and sometimes these have paper equivalents (or related paper publications.

ELECTRONIC MAIL:

1) The delivery of mail or messages: A public or private data communications system.

2) A common-carrier data communications service to transmit computer-generated messages between locations or cities 3) A feature of LANs for transmission of computer-generated messages within a closed community of users on the LAN. See E-Mail

ELECTRONIC SWITCHING SYSTEM (ESS) / ELECTRONIC SWITCH:

See ESS

ELMI:

Enhanced Local Management Interface

ELECTRONIC TANDEM NETWORK (ETN):

1.) A private network automatically and electronically connecting the calling office to the called office through Tandem-Tie-Trunks. The network switches may also function as PBXs.

2.) An AT&T product name

3.) Used as a generic term for a PBX-based private network.

EM:

End-of-Medium: A control character. EM is used within a message (block) to mark the end of text in a block containing 79 characters or less. An ETB or ETX framing character normally follows it.

EMA:

1) Enterprise Management Architecture: Digital Equipment Corporation network management architecture, based on the OSI network management model.

2) Electronic Messaging Association: Forum devoted to standards and policy work, education, and development of electronic messaging systems, such as e-mail, voice mail, and facsimile.

E-MAIL:
Electronic Mail: Whenever one sends messages to people using a computer and they read it later, you've sent a piece of e-mail. E-mail can be sent it to a single recipient or to many. All e-mail is basically processed in the same manner. E-mail, when transmitted, is sent to a virtual mailbox and the recipient picks it up manually within the computer or can use software that does it automatically.

EMA/EMB/EMC:

Extended Memory Controller Interface (transfer channel) for disc memory (replaced Magnetic Tape A, B and C devices and transfer channels).

EMA/B LTC:

Extended Memory disk units, 25 megabits each; used for temporary in transit storage; replaced the MMU/Ferranti drives.

EMBEDDED OBJECT:

Information created in another program that has been pasted inside a document. When information is embedded, the information in the new document can be edited using toolbars and menus from the original program. Embedded information is not linked to the original source. If information is changed in one place, it is not updated in the other.

EMC PROVEN E-INFOSTRUCTURE:

An EMC program that recognizes corporations that operate in the 24-hour Internet workday and that adhere to the highest levels of information availability and customer satisfaction.

EMI:

Electromagnetic Interference (Magnetic field): Refers to undesirable radiation or interference caused by magnetic fields across wires/cables or by motors. Can be reduced or eliminated through the use of shielded cables or other shielding means.

EMIF:

ESCON Multiple Image Facility: Mainframe I/O (Input/Output) software function that allows one ESCON (Enterprise System Connection Channel) to be shared among multiple logical partitions on the same mainframe.

EMOD-1:

Evolutionary Modernization (ICCDP enhancement program): This upgrade program replaced the existing main frames (CDP) with integrated logic main frames (ICCDP).

EMP:

1) High Speed Printer Transfer Channel (port) between the mainframe computer and the High Speed Printer.

2) Electromagnetic Pulse: Caused by lightning and other high-energy phenomena capable of inducing enough energy into unshielded conductors to destroy electronic devices

EMPTY SLOT RING:

A Local Area Network (LAN) function where an empty packet may circulates through each station in a LAN ring. A single bit within the header of the packet indicates if a message is present and, if so, a destination and source address will be included.

EMS:

1) Event Management Service. A software module within the ICM that processes user reported events to other processes within the system.

2) Element Management System

EMS / EMS UNIBUS:

Extended Memory System / Interface Media: Installed between the mainframe and the external memory system.

EMTOX:

Exchange of Mixed Traffic over X.25: Specification for transmitting airline protocol data over standard X.25 Switched Virtual Circuits (SVC).

EMULATE:

The use of hardware and/or software on a Personal Computer (PC) or smart terminal that allows the terminal to imitate the operation of a host computer or another terminal,

EMULATION / EMULATION MODE:

1) The ability of one device to mimic the operations of another device; a common use involves running software on a microcomputer that allows it to operate as a terminal.

2) Function of an NCP that enables it to perform activities equivalent to those performed by a transmission control unit.

EMULATOR:

A process of using the appropriate Hardware and/or software in a computer system which causes the system to appear as if it were another system.

EN:

End Node: APPN end system that implements the PU 2.1, provides end-user services, and supports sessions between local and remote Control Points (CP). EN(s) are not capable of routing traffic and rely on an adjacent Network Node (NN) for APPN services.

ENCAPSULATION:

Wrapping of data in a particular protocol header: For example, Ethernet data is wrapped in a specific Ethernet header before network transit. Also, when bridging dissimilar networks, the entire frame from one network is placed in the header used by the data link layer protocol of the other network.

ENCAPSULATION BRIDGING:

Carries Ethernet frames from one router to another across dissembler media: such as serial and FDDI lines.

ENCODE:

To use an analog or binary code to represent individual characters or groups of characters in a message; or the process of changing data into a series of electrical or optical pulses that can travel efficiently over a transmission medium.

ENDCODER / ENDCODING / DECODING:

Formatting data into a pattern suitable for data communication

ENCRYPTED VIRUS:

An encrypted virus(s) code begins with a decryption algorithm and continues with scrambled or encrypted code for the remainder of the virus. Each time it infects, it automatically encodes itself differently, so its code is never the same. Through this method, the virus tries to avoid detection by anti-virus software.

ENCRY PTION CERTIFICATE:

Public-key certificate that contains a public key for encrypting data and not intended for use in verifying digital signatures or performing other cryptographic functions

ENCRYPTING FILE SYSTEM (EFS):

A feature in some versions of Windows: Enables users to encrypt files and folders on an NTFS volume disk to keep them safe from access by intruders.

ENCRYPTION:

Encryption is the process of changing data into a form that can be read only by the intended receiver. To decipher the message, the receiver of the encrypted data must have the proper decryption key. In traditional encryption schemes, the sender and the receiver use the same key to encrypt and decrypt data. PGP (Pretty Good Privacy) and DES (Data Encryption Standard) are two popular public-key encryption schemes.

END NODE:

A network node that cannot forward packets intended for other nodes. An end node supports only a single active line.

END OF ADDRESS:

The character used to separate the address or routing part of a message from the remainder of the message; ‘End-of-Routing Symbol’.

END OF MESSAGE:

See EOM

END OF TRANSMISSION:

See EOT

END OFFFICE:

The first central office location to which a subscriber telephone line is connected, or the end switching office for a dialed connection.

END POINT:

1) Device at which a virtual circuit or virtual path begins or ends

2) H.323 terminal or gateway. An endpoint can call and be called. It generates and terminates the information stream.

END - TO - END ENCRYPTION:

Continuous protection of data that flows between two points in a network; provided by encrypting data when it leaves its source, leaving it encrypted while it passes through any intermediate computers (such as routers), and decrypting only when the data arrives at the intended destination.

END USER:

A person or company that uses telecommunications products and services; The End User could be people, computers, objects, switches, or other types of computer systems or communications equipment.

END-TO-END DIGITAL TRANSMISSION:

A digital operating circuit, which does not require a MODEM

ENHANCED IGRP:

Enhanced Interior Gateway Routing Protocol: Advanced version of IGRP developed by Cisco. Provides superior convergence properties and operating efficiency, and combines the advantages of link state protocols with those of distance vector protocols.

ENHANCED MONITORING SERVICE:

Set of analysis tools on the Catalyst 5000 switch, consisting of an integrated RMON agent and the SPAN. These tools provide traffic monitoring and network segment analysis and management.

ENQ:

Enquiry: An ASCII response request control character normally sent from a called station.

ENTERPRISE NETWORK:

A network (usually large) that connects all sites of a particular organization together

ENTERPRISE STORAGE:

A combination of intelligent storage systems, software and services: Together, these products and services enable an enterprise to store, retrieve, manage, protect and share information from all major computing environments, including UNIX, Windows 2000 and mainframe platforms

ENTITY:

Generally, an individual manageable network device, sometimes called an alias.

ENTITY IDENTIFIER:

The unique address of a NVE socket in a node on an AppleTalk network: The specific format of an entity identifier is network-dependent.

ENTITY NAME:

Name that a NVE can assign to itself: Although not all NVE(s) have names, NVE(s) can possess several names (or aliases). An entity name is made up of three character strings: object, entity type, and zone. For example: Bldg 4 LaserJet 5:LaserReader@Bldg 6 Zone.

ENTITY TYPE:

Part of an entity name that describes the entity's class: For example, LaserWriter or AFP-Server.

ENTRANCE FACILITY:

1) A facility connecting a point of presence (POP) with its serving wire center. Entrance facilities permit an inter-exchange carrier to connect its network with the exchange's local access network.

2) A facility that connects a cable head or earth station to a carrier's switching center.

ENVELOP DELAY:

Characteristics of a circuit where some simultaneously transmitted frequencies are delayed relative to the other frequencies.

EO:

Elementary Operation: Similar to Macro Instructions; programming (software) function (method) used in the AUTODIN computer system.

EOA:

End of Address (header): Defines where the address part of a message ends; a control character.

EOB:

End of Block: Defines the end of a block of data during transmission; a control character.

EOC:

Elementary Operation Control: An internal program control function.

EOF:

End-Of-File: A data storage media marker to indicate the end of a recorded file; a control character.

EOLB:

End-Of-Line-Block: An end of multiple blocks of data indicator; a control character.

EOM:

End-Of-Message/File: An end of message or a file designator; a control character or a group of alpha/numeric characters.

EOT:

End-Of-Transmission (ASCII control character): Indicates the end of each individual data (message) transmission period.

EPD:

Early Packet Discard: Mechanism used by some ATM switches for discarding a complete AAL5 frame when a threshold condition, such as imminent congestion, is met. EPD prevents congestion that would otherwise jeopardize the switch(s) capability to properly support existing connections with a guaranteed service.

EPHEMERAL KEY:

A public key or a private key that is relatively short-lived.

EPROM:

Erasable Programmable Read Only Memory: Unlike dynamic and static RAM, EPROM chips do not require power to retain their data. EPROM chips are commonly used to store BIOS (Basic Input-Output System) information and basic software for a MODEM, video cards, and other peripherals. EPROM’s can be erased by exposure to ultraviolet light and then reprogrammed using a device called a PROM burner.

EPSCS:

Enhanced Private Switched Communications Service: A private network utilizing carrier provided equipment located in the central office (CO) and dedicated to a specific customer.

EQUALIZATION:

A compensating process that corrects signal quality problems, which may involve signal amplitude, signal delay, or signal distortion.

EQUALIZER:

A combination of coils, capacitors, and/or resistors connected or inserted in a transmission line or amplifier circuit to improve its frequency response.

EQUALIZER, ADAPTIVE:

A term used to identify a dynamically changing equalizer, which continuously compensates for detected line distortion.

EQUALIZER DELAY:

A corrective function that causes the signal phase or envelop delay of a circuit to remain substantially constant over a desired frequency range.

EQUIPMENT ROOM:

Could be any location where telecommunications switching equipment, transmission equipment, terminals or circuit connecting blocks are installed.

ER:

Explicit Rate: In ATM, an RM cell used to limit the ACR for a transmission to a specific value. Usually the source sets the ER initially to a requested rate, such as the PCR. Later, any network element in the path can reduce the ER to a value that the element can sustain.

ERC:

Easily Recognizable Code: Part of a North American number, in the Numbering Plan Area (NPA) position, using the pattern NXX, where N=2----9 and XX = 00, 22, 33----- 88.

ERL:

Echo Return Loss: The introduced attenuation of echo currents (signals) in one direction to counteract the echo caused by telephone circuits in the other direction.

ERLANG:

A term used for a data communications measurement standard, which is used to measure and rate traffic volume and usage.

ERROR:

A discrepancy between a generated, observed or measured quantity and the true, specified, or correct value or condition. The dropping or gaining of a bit in a data stream during transmission (error received). See Parity.

ERROR CODE:

A specific character, which is transmitted to indicate an error was detected in the appropriate block of data so corrective action can be taken.

ERROR CONTROL / CORRECTION:

Refers to system or terminal error correction functions where messages (data) received with an error(s) will be retransmitted or local correction schemes will be performed on the received data.

ERROR CORRECTION CODING (ECC):

An encoding method that detects and corrects errors at the receiving end of data transmission: ECC is used by most MODEM(s).

ERROR RATE:

Usually refers to a percentage measurement of data integrity, referenced in blocks, characters or bits incorrectly received.

ERSD:

Estimated Return to Service Date

ES:

1) End System: Non-routing host or node in an OSI network.

2) Error-ed Second: A one-second interval during which one or more errors are detected; a performance monitoring (PM) parameter, measured on a per-channel basis.

ESC:

Escape: A control character used to provide code extension, which affects the interpretation of a limited number of contiguously following characters.

ESCAPE SEQUENCE:

A sequence of characters (usually +++), that causes the MODEM to change from a data mode to a command mode.

ESCON:

Enterprise System Connection: IBM channel architecture that specifies a pair of fiber-optic cables, with either LED(s) or lasers as transmitters, and a signaling rate of 200 Mbps.

ESCON CHANNEL:

IBM channel for attaching mainframes to peripherals, such as storage devices, backup units, and network interfaces: This channel incorporates fiber channel technology. The ESCON channel replaces the bus and tag channel.

ESD:

Electrostatic Discharge: Discharge of stored static electricity that can damage electronic equipment and electrical circuitry, resulting in complete or intermittent failures.

ESF:

1) Extended Super-frame Format: A network control and framing protocol, used by common carriers, that incorporates both control and information data in the transmitted bit stream. When connecting networks and equipment it is necessary for both the equipment and the network to support the same appropriate protocols.

2) Extended Super-Frame: Refers to a framing type used on T1 circuits that consists of 24 frames of 192 bits each, with the 193rd bit providing timing and other functions. ESF is an enhanced version of SF.

ESI:

End System Identifier: Identifies multiple nodes at the same level when the lower level peer group is partitioned, usually an IEEE 802 address.

ES-IS:

End System-to-Intermediate System: OSI protocol that defines how end systems (hosts) announce themselves to intermediate systems (routers).

ESL:

Enterprise Solutions Limited

ESMR:

Enhanced Specialized Mobile Radio: Refers to the use of frequency bands originally allocated for two-way dispatch services: Companies such as Nextel and Southern LINC have built digital mobile phone services similar to cellular and PCS (Personal Communication Services) systems.

ESMTP:

Extended Simple Mail Transfer Protocol: An extended version of the Simple Mail Transfer Protocol (SMTP), which includes additional functionality, such as delivery notification

ESN:

Enterprise Storage Network: A specialized, open network that is designed to offer universal data access for every major computing platform, operating system, and application in the world across any combination of SCSI, Ultra SCSI, Fiber Channel, and ESCON® technologies.

ESN:

Electronic Serial Number: The unique serial number of a cellular phone that identifies it to the cellular system for placing and receiving calls

ESNET:

Energy Sciences Network: Data communications network managed and funded by the U.S. Department of Energy Office of Energy Research (DOE/OER); interconnects the DOE to educational institutions and other research facilities.

ESP:

1) Extended Services Processor.

2. Encapsulating Security Payload: Security protocol that provides data privacy services, optional data authentication, and anti-replay services. ESP encloses the data to be protected.

ESS:

1) Electronic Switching System: Composed of solid state electronics, integrated circuits (chips) and other computer type equipment. AT&T term for an electronic central office switch

2) A computerized, digital telephone switching system, manufactured by AT&T, utilizing a program to control the switching function. With ESS, custom calling features such as Call Waiting, Call Forwarding and Three-Way calling are available to the subscriber.

ESSENTIAL FACILITIES:

A term used in packet switched environments to define the standard facilities found on all networks.

ETB:

End of Transmission Block: A control character specifying the end of a block of data.

ETH UNIT:

Ethernet Unit: Unit that provides interfaces to the Management Bus Concentrator and the network management system (NMS).

ETHER TALK:

Apple Computer's data-link product that allows an AppleTalk network to be connected by Ethernet cable

ETHERCHANNEL:

Developed and copyrighted by Cisco Systems: Logical aggregation of multiple Ethernet interfaces used to form a single higher bandwidth routing or bridging endpoint.

ETHERLOOP:

A short term for Ethernet Local Loop: a proprietary Nortel, technology.

ETHERNET:

10 base thick wire to DEC hubs: A common electronic bus for data transfer between processing units (computers / terminals). 10BaseT denote a peak transmission speed of 10 mbps using copper twisted-pair cable.

ETHERNET CONNECTION:

A high-speed direct connection to a network via an Ethernet Network interface (NIC) card; this allows a user to access any host connected to the network.

ETHERNET INTERFACE PROCESSOR (EIP):

Interface processor card on the Cisco 7000 series routers: The EIP provides high-speed (10-Mbps) AUI ports that support Ethernet Version 1 and Ethernet Version 2 or IEEE 802.3 interfaces, and a high-speed data path to other interface processors.

ETHERNET MELTDOWN:

Event that causes saturation, or near saturation, on an Ethernet: It usually results from illegal or misrouted packets and typically lasts only a short time.

ETIC:

Estimated Time for Completion

ETMS:

Enhanced Traffic Management System

ETN:

Electronic Telecommunications Network

ETR:

Effective Transmission Rate: A designated rate of transmission allowed based on the transmission media conditions. A MODEM or other control devices may accomplish this manually or automatically.

ETR Channel:

Effective Transmission Rate: A programming feature used in the CONUS ASC (Automatic Switching Center) to eliminate the inherit delay between messages that would normally occur. ETR service is used on all IST Trunks between the CONUS ASC’s and some high-speed terminals.

ETSI:

European Telecommunications Standards Institute: ETSI is a non-profit organization producing voluntary telecommunications standards used throughout Europe; some have been adopted by the EC as the technical base for Directives or Regulations.

ETX:

End of Text: A data control character indicating the end of the text section of a message.

EUNET:

European Internet: European commercial Internet service provider. EU-net is designed to provide e-mail, news, and other Internet services to European markets.

EUROPEAN COMPUTER MANUFACTURERS ASSOCIATION:

See ECMA

EVENT:

A network message indicating operational irregularities in the physical elements of a network or a response to the occurrence of a significant task; or the beginning of ending of a task

EVENT DETECTION POINT:

An Intelligent Network terminology

EWOS:

European Workshop for Open Systems: The OSI Implementations Workshop for Europe.

EXCESS RATE:

In Asynchronous Transfer Mode (ATM) traffic in excess of the insured rate for a given connection. Specifically, the excess rate equals the maximum rate minus the insured rate. Excess traffic is delivered only if network resources are available and this excess traffic may be discarded during periods of congestion.

EXCESSIVE ZEROS:

Normally refers to sixteen or more zeros in a row

EXCHANGE:

In telecommunications the term normally refers to central offices and equipment belonging to the Telephone Company.

EXCHANGE, PRIVATE AUTOMATIC (PAX):

Private Automatic Exchange: Refers to a privately operated dial telephone/data exchange, which is not available to the general public. The exchange may be a data PABX, voice PABX or voice/data PABX.

EXCHANGE, PRIVATE AUTOMATIC BRANCH (PABX):

See Exchange, Private Automatic (PAX)

EXE FILE:

An executable file: As contrasted with a document or data file; usually, executed by double-clicking its icon or a shortcut on the desktop, or by entering the name of the program at a command prompt. Executable files can also be executed from other programs, batch files or various script files. The majority of known viruses infect program files.

EXEC:

Interactive Command Processor of Cisco IOS

EXPANDED MEMORY:

A type of memory that can be added to IBM personal computers: The use of expanded memory is defined by the Expanded Memory Specification (EMS), which supports memory boards containing RAM that can be enabled or disabled by software.

EXPANDER (Transducer):

A device used to increase voltage amplitudes within a given range.

EXPANSION:

The process of running a compressed data set through an algorithm that restores the data set to its original size

EXPEDITED DELIVERY:

Option set by a specific protocol layer telling other protocol layers, or the same protocol layer in another network device, to handle specific data more rapidly.

EXPLICIT ACCESS:

Refers to a Local Area Network (LAN) shared access function, which allows stations to make use of the network individually for a given time period. Each station receives a requested turn in order.

EXPLICIT ROUTE:

In SNA, a route from a source sub-area to a destination sub-area, as specified by the responsible connecting sub-area nodes and transmission groups

EXPLORER FRAME:

Frame sent out by a networked device in an SRB environment to determine the optimal route to another networked device.

EXPLORER PACKET:

Generated by an end station trying to find its way through an SRB network; the station gathers a hop-by-hop description of a path through the network by being marked (updated) by each bridge that it traverses, which completes topological map.

EXTENDED ADDRESSING:

Communication systems feature where an address may be increased in size. This usually is allowed in bit-oriented protocols. IBM System Network Architecture (SNA) adds two high order bits to the basic address.

EXTENDED AREA SERVICE (EAS):

A common carrier telephone service that provides for calls to be expanded to a designated area extending beyond the local exchange.

EXTENDED CHARACTERS:

Any of the 128 additional characters in the extended ASCII (8-bit) character set. These characters include those in several non-English languages, such as accent marks, and special symbols used for creating pictures.

EXTENDED LABEL ATM INTERFACE:

A type of interface supported by the remote Asynchronous Transfer Mode (ATM) switch driver and a particular switch-specific driver that supports MPLS over an ATM interface on a remotely controlled switch.

EXTENDED MEMORY:

Memory beyond one megabyte in 80286, 80386, 80486, and Pentium computers

EXTENDED PARTITION:

A type of partition that can be created only on basic Master Boot Record (MBR) disks: Extended partitions are useful for creating more than four volumes on a basic MBR disk. Unlike primary partitions, an individual does not format an extended partition with a file system and then assign a drive letter to it. Instead, one creates one or more logical drives within the extended partition. After an individual creates a logical drive, it must be formatted a drive letter assigned. An MBR disk can have up to four primary partitions, or three primary partitions, one extended partition, and multiple logical.

EXTENDED SERVICES PROCESSOR:

Rack-mounted processor that is co-located with a Cisco BPX / AXIS and all three units comprise a BPX service node, and has IP connectivity to a StrataView Plus Workstation.

EXTENSIBLE FIRMWARE INTERFACE (EFI):

In computers with the Intel Itanium processor: the interface between a computer's firmware, hardware, and the operating system. The Extensible Firmware Interface defines a new partition style called GUID Partition Table (GPT). EFI serves the same purpose for Itanium-based computers as the BIOS found in x86-based computers. However, it has expanded capabilities that provide a consistent way to start any compatible operating system and an easy way to add EFI drivers for new bootable devices without the need to update the computer's firmware.

EXTENSIBLE MARKUP LANGUAGE (XML):

A meta-markup language that provides a format for describing structured data. This facilitates more precise declarations of content and more meaningful search results across multiple platforms.

EXTERIOR ROUTER:

Router connected to an AURP tunnel, responsible for the encapsulation and the de-encapsulation of AppleTalk packets in a foreign protocol header (example: IP).

EXTERNAL ATM INTERFACE:

One of the interfaces on the controlled Asynchronous Transfer Mode (ATM) switch other than the switch control port; also known as an exposed ATM interface because it is available for connections outside the label controlled switch.

EXTERNAL MODEM:

A MODEM that is attached to a serial port and is placed outside the computer; contrast with an internal MODEM, which normally is a circuit card inserted into a computer slot.

EXTRACT:

When extracting a file this would be the uncompressed copy of the file that is created in a specified folder. The original file remains in the compressed folder.

EXTRANET:

An intranet that is accessible to computers that are not physically part of a companies own private network, for example, to allow vendors and business partners to access a company web site.

Often an intranet will make use of a Virtual Private Network (VPN).

EXZ:

Excessive Zeros