Glossary-I
A Data Communication Historical Series
By Bob Pollard

HOME                      INDEX

I&A: Identification and Authentication

IAB:

Internet Architecture Board: A board of inter-network researchers: Responsible for appointing a variety of Internet-related groups, such as the IANA, IESG, and IRSG. The IAB is appointed by the trustees of the ISOC.

IAC:

Initial Alignment Control: SS7 MTP 2 function that provides the link alignment processing

IAHC:

Internet International Ad Hoc Committee: A coalition of participants from the broad Internet community that work to satisfy the requirement for enhancements to the Internet's global DNS. Organizations naming members to the committee include Internet Society (ISOC), Internet Assigned Numbers Authority (IANA), Internet Architecture Board (IAB), Federal Networking Council (FNC), International Telecommunication Union (ITU), International Trademark Association (INTA), and World Intellectual Property Organization (WIPO).

IANA:

Internet Assigned Numbers Authority: An organization operated under the auspices of the ISOC as a part of the IAB. IANA delegates authority for IP address-space allocation and domain-name assignment to the Inter-NIC and other organizations. IANA also maintains a database of assigned protocol identifiers used in the TCP/IP stack, including autonomous system numbers.

IBC:

In-Band Control: Refers to issuing MICA technologies commands on the data channel, versus OBC, on the out-of-band control channel. In-band commands are passed by setting an in-band-command bit in the data buffer.

IBM:

International Business Machines Corporation

IBM CARD:

A paper (hard) card used in the original IBM data processing card machines and by the Compound Terminals used in the AUTODIN system. The card used in the Compound Terminal was the same dimensions as the data processing card, but did not use the same data code set configuration. The data processing card used a 12 bit Hollerith code set, where the Compound Terminal used a modified 8-bit U. S. Military code set called Fieldata (Field Data). This was a compromise between conflicting commercial codes.

IC:

Integrated Circuit: A semiconductor device, also known as a microchip, containing transistor functions, resistors, diodes, capacitors, etc. An IC can perform numerous functions, such as processing, data storage and program storage. IC would include PROM, EEPROM, EPROM, ROM and RAM.

ICANN:

Internet Corporation for Assigned Names and Numbers: A non-profit, private corporation that assumed responsibility for IP address space allocation, protocol parameter assignment, domain name system management, and root server system management functions; formerly performed under U.S. Government contract by IANA and other entities.

ICC:

Interface Controller Card: A high-capacity network interface card used in Cisco VCO/4K. The ICC is inserted into the VCO/4K mid-plane, connecting with a series of I/O modules specific to different network interface requirements.

ICCDP:

Integrated Circuit Communications Data Processor

ICD:

International Code Designator: One of two ATM address formats developed by the ATM Forum for use by private networks. Adapted from the sub-network model of addressing in which the ATM layer is responsible for mapping network layer addresses to ATM addresses.

ICM:

Intelligent Call Management: The Cisco system that implements enterprise-wide call distribution across call centers. The ICM provides pre-routing, post-routing, and performance monitoring capabilities.

ICMP:

Internet Control Message Protocol: Defines the protocol used to handle errors and control messages at the Internet protocol layer. ICMP is considered to be a part of IP and is used to test whether a destination is available and responding.

ICMP FLOOD:

Denial of service attack that sends a host more ICMP echo request (ping) packets than the protocol implementation can handle.

ICON:

A small image displayed on the screen to represent an object and the image can be manipulated by the user. Icons serve as visual mnemonics and allow the user to control certain computer actions without having to remember commands or input them from the keyboard.

ICP:

Intelligent Call Processing: AT&T name for the facility that allows third-party products, such as the ICM, to pre-route calls.

ICP CELL:

IMA control protocol cell used for aligning the cells in multiple links

ICPIF:

Calculated Planning Impairment Factor (loss/delay busy-out threshold): The ICPIF numbers represent predefined combinations of loss and delay. Packet loss and delay determine the threshold for initiating the busy-out state.

ICR:

Initial Cell Rate

ICRL:

Indirect Certificate Revocation List: In X.509, a CRL that may contain certificate revocation notifications for certificates issued by CA(s) other than the issuer of the ICRL.

ICU:

Instruction Control Unit: An internal mainframe program (software) instruction management unit.

I-D:

Internet-Draft: Working documents of the IETF, from its Areas and Working Groups. They are valid for a maximum of six months and might be updated, replaced, or made obsolete by other documents at any time. Often, I-Ds are precursors to RFC(s).

IDB:

Interface Description Block: An IDB sub-block is an area of memory that is private to an application. This area stores private information and states variables that an application wants to associate with an IDB or an interface. The application uses the IDB to register a pointer to its sub-block, not to the contents of the sub-block itself.

IDEA:

International Data Encryption Algorithm: Patented, symmetric block cipher that uses a 128-bit key and operates on 64-bit blocks.

IDENTIFICATION, TERMINAL:

A character or sequence of characters, bit or bits used to identify an originating or transmitting terminal.

IDF:

Intermediate Distribution Frame: A connecting frame and/or connecting blocks used to interconnect data communications equipment.

IDI:

Initial Domain Identifier: Portion of an NSAP or NSAP-format ATM address that specifies the address allocation and the administration authority.

IDIQ:

Indefinite Delivery-Indefinite Quantity: A contract which provides an easy and simple ordering process in which orders are excluded from the requirement to obtain competition in accordance with FAR 6.001 (e).

IDLE CHARACTER:

Normally refers to idle line fill characters, Sync characters, Nul characters, etc.

IDN:

International Data Number:

IDP:

Initial Domain Part: Part of a CLNS address that contains an authority and format identifier and a domain identifier.

IDPR:

Inter-domain Policy Routing: Inter-domain routing protocol that dynamically exchanges policies between autonomous systems. IDPR encapsulates inter-autonomous system traffic and routes it according to the policies of each autonomous system along the path.

IDRP:

IS-IS Inter-domain Routing Protocol: OSI protocol that specifies how routers communicate with routers in different domains.

IE:

Information Element

IEC:

1) Inter-Exchange Carrier: An FCC licensed common carrier permitted to carry subscribers transmissions inter- LATA (Local Access and Transport Area), or if approved by a PUC or PSC, intrastate.

2) International Electro-technical Commission: Industry group that writes and distributes standards for electrical products and components.

IEEE:

Institute of Electrical and Electronic Engineers: An international institute that issues communications standards and is a member of American National Standards Institute (ANSI) and International Standards Organization (ISO), probably best known for its development of IEEE Project 802.

IEEE Project 802:

The IEEE developed 802 series of local area network (LAN) standards.

IEEE 802.1:

IEEE specification that describes an algorithm that prevents bridging loops by creating a spanning tree. The algorithm was invented by Digital Equipment Corporation. The Digital algorithm and the IEEE 802.1 algorithm are not the same, nor are they compatible.

IEEE 802.2:

A LAN standard for the Data Link Layer used with other Project 802 standards: LAN protocol that defines the implementation of the LLC sub-layer of the data link layer. IEEE 802.2 handles errors, framing, flow control, and the network layer (Layer 3) service interface.

IEEE 802.3:

A LAN standard for the physical layer using the Carrier Sense Multiple Access/Carrier Detect (CSMA/CD) access method: similar to Ethernet, within a bus topology: LAN protocol that defines the implementation of the physical layer and the MAC sub-layer of the data link layer. IEEE 802.3 uses CSMA/CD access at a variety of speeds over a variety of physical media. Extensions to IEEE 802.3 specify implementations for Fast Ethernet.

IEEE 802.4:

A LAN standard: The physical layer using a token passing access method within a bus topology:

A LAN protocol for implementation of the physical layer and the MAC sub--layer for the data link layer; uses token-passing access over a bus topology and is based on the token bus LAN architecture.

IEEE 802.5:

A LAN standard: The physical layer using the token ring or token passing access method in a ring topology. A LAN protocol that specifies the implementation of the physical layer and MAC sub-layer of the data link layer; uses token passing access at 4 or 16 Mbps over STP cabling and is similar to IBM Token Ring.

IEEE 802.6:

IEEE MAN specification based on DQDB technology: IEEE 802.6 supports data rates of 1.5 to 155 Mbps.

IEEE 802.12:

IEEE LAN standard that defines the physical layer and the MAC sub-layer of the data link layer; IEEE 802.12 uses the demand priority media-access scheme at 100 Mbps over a variety of physical media.

IEEE 488:

An IEEE standard Parallel Interface used to connect data communications equipment via connecting blocks.

IEEE 1394

A standard for high-speed serial devices such as digital video and digital audio editing equipment

IEEE 1394 CONNECTOR:

A type of connector that enables a user to connect and disconnect high-speed serial devices: An

IEEE 1394 connector is usually on the back of the computer near the serial port or the parallel port.

   If a device is IEEE 1394 compatible, a user can connect the device to the IEEE 1394 connector while the computer is running and Windows will detect the device and inform the user when the device is ready for use. Similarly, a user can unplug the device while the computer is running; but use the Add Hardware Wizard to inform Windows that the device is being removed. Windows will then advice when the device can be unplugged from the computer.

   The IEEE 1394 bus is used primarily to connect high-end digital video and digital audio devices to the computer; however, some hard disks, printers, scanners, and DVD drives can also be connected to the computer using the IEEE 1394 connector.

IEEE 1394 PORT:

Ports that support either a 6-pin plug: 11 mm by 5.4 mm or a 4-pin plug: 5.35 mm by 3.45 mm.

IEPG:

Internet Engineering Planning Group: A group primarily composed of Internet service operators that promote a globally coordinated Internet operating environment. Membership is open to all.

IESG:

Internet Engineering Steering Group: An organization appointed by the IAB that manages the operation of the IETF.

IETF:

Internet Engineering Task Force: Task force consisting of over 80 working groups responsible for developing Internet standards. The IETF operates under the auspices of ISOC.

IF:

Intermediate Frequency: Intermediate electromagnetic frequencies generated by a super- heterodyne radio receiver.

IFIP:

International Federation for Information Processing: Research organization that performs OSI pre-standardization work. IFIP formalized the original MHS model.

I-FRAME:

Information Frame: One of three SDLC frame formats.

IF-MIB:

Interfaces Group MIB: The current specification for the IF-MIB is found in RFC 2233. The MIB module describes generic objects for network interface sub-layers. This MIB is an updated version of the MIB-II if Table, and incorporates the extensions defined in RFC 1229.

IGMP:

Internet Group Management Protocol: Used by IP hosts to report their multicast group memberships to an adjacent multicast router.

IGP:

Interior Gateway Protocol: Internet protocol used to exchange routing information within an autonomous system. Examples of common Internet IGP(s) include IGRP, OSPF, and RIP.

IGRP:

Interior Gateway Routing Protocol: IGP developed by Cisco to address the issues associated with routing in large, heterogeneous networks

IIH:

IS-IS Hello: Message sent by all IS-IS systems to maintain adjacencies.

IINREN:

Interagency Interim National Research and Education Network; evolving operating network system: Near term research and development activities that will provide for the smooth evolution of this networking infrastructure into the gigabit NREN.

IIOP:

Internet Inter-ORB Protocol: Protocol used in the CORBA framework for accessing objects across the Internet.

IISP:

Interim-Inter-switch Signaling Protocol: ATM signaling protocol for inter-switch communication using manually configured prefix tables. When a signaling request is received by a switch, the switch checks the destination ATM address against the prefix table and notes the port with the longest prefix match. It then forwards the signaling request across that port using UNI procedures. Formerly known as PNNI Phase 0

IITA:

Information Infrastructure Technology and Applications: Component of the HPCC program intended to ensure U.S. leadership in the development of advanced information technologies.

IKE:

Internet Key Exchange: IKE establishes a shared security policy and authenticates keys for services, such as IP-Sec, that require keys. Before any IP-Sec traffic can be passed, each router/firewall/host must verify the identity of its peer. This can be done by manually entering pre-shared keys into both hosts or by a CA service.

ILEC:

Incumbent Local Exchange Carrier; a traditional telephone company: In the U.S., the Regional Bell Operation Companies (RBOC) that were formed after the divestiture of AT&T and the Independent Operating Companies (IOC) located in more rural areas, or in single cities ILEC(s). In other areas of the world, ILEC(s) are the Post, Telephone, and Telegraphs (PTT); government-managed monopolies.

ILMI:

Interim Local Management Interface: Specification developed by the ATM Forum for incorporating network-management capabilities into the ATM UNI.

IMA:

1) Input Message Acknowledgment (Ack): An acknowledgment message returned to the sender from the receiving station (terminal). The Ack message may be one or more characters or bits.

2) Inverse Multiplexing over ATM: Standard protocol defined by the ATM Forum in 1997.

IMA GROUP:

Physical links grouped to form a higher-bandwidth logical link the rate of which is approximately the sum of the individual link rates.

IMAP / IMAP4:

1) Internet Message Access Protocol: Is gradually replacing POP as the primary protocol used by email ‘Clients’ when communicating with email Servers. IMAP, when used for an email client program, can not only retrieve email but can also manipulate message stored on the server, without having to actually retrieve the messages. Messages can be deleted, have their status changed, and multiple mailboxes can be managed, etc.

2) Internet Message Access Protocol, version 4: Internet protocol allows a client workstation to access a mailbox dynamically on a server host to manipulate and retrieve mail messages that the server has received and is holding for the client.

IMHO:

In My Humble Opinion: A shorthand acronym appended to a comment written in an online forum; IMHO indicates that the writer is aware that a debatable view is being expressed, probably on a subject already under discussion. One of many such shorthand acronyms in common use online, especially in discussion forums.

IMMEDIATE START:

A method of E&M (Receive / Transmit) signaling: When the signaling leads indicate a change to an off-hook state, the interface is immediately ready to send information.

IMP:

Interface Message Processor: Old name for ARPANET packet switches.

IMPEDANCE:A device connection media: Overcomes signal deterioration caused by varying currents, resistance, capacitance, and inductance. Line impedance (AC resistance), if increased via inductance will allow a greater amount of power to be transmitted with less current, but at a higher voltage.

IMPULSE HITS (SPIKES):

Impulse hits (spikes) are impulse noise caused errors adversely affecting data communication.

IMPULSE NOISE:

A communications line interference caused by intermittent electrical action; lightning, on/off switch action, static, etc., usually high amplitude and short duration.

IMPULSE RULE:

A sequence of instructions that define autonomous call processing actions to be completed on incoming ports in the Cisco VCO/4K switch.

IMPULSES:

Refers to the closing and breaking of a circuit by pulsing contacts to signal or operate remote devices.

IMSI:

International Mobile System Identifier: A unique identifier stored in the SIM of a mobile station. The MS sends the IMSI to a BTS for identification of the MS in the GSM network. The BTS looks for the IMSI in the HLR.

IMS/VS:

Information Management System/Virtual Storage: Refers to an IBM software product designed for both batch processing and data communications based processing.

IMT:

Inter-Machine Trunk

IMT2000:

A set of proposals for standards defining 3G (Third Generation Wireless) wireless network performance; compiled by the ITU (International Telecommunications Union), an organization of the United Nations.

IN THE WILD:

A virus is ‘in the wild’ if it is verified as having caused an infection outside a laboratory situation. Most viruses are in the wild and differ only in prevalence.

INA:

1) Interactive Network Adapter: Central point or hub in broadband networks that receives signals on one frequency band and retransmits them to another. Every transmission in a broadband network has to go through the INA or head-end. In CATV technology, the head-end is the control center for a cable system where video, audio, and data signals are processed and distributed along the coaxial cable network.

2) Information Networking Architecture: Bellcore object-oriented architecture for the management of ATM and SONET equipment and services in an operating company environment.

IN/AIN:

Intelligent Network/Advanced Intelligent Network

INAP:

Intelligent Network Application Part: SS7 architectural protocol layer.

INASOFT:

Bellcore implementation of INA

INB:

Install Busy: An entity just created but has not been placed In-Service or Out-of-Service yet.

IN-BAND SIGNALING:

Refers to transmission within a frequency range normally used for information transmission

INCRP:

Intelligent Network Call Routing Protocol: The communication protocol used by ICM gateways to pass a routing request and response between two ICM(s). The ICM sending the request must be set up for remote network routing and the ICM receiving the request must be running an INCRP Network Interface Controller (NIC).

INDIVIDUAL MESSAGE SERVICE:

A service level that includes Individual Message services (E-mail) and a set of shared, enhanced functions across the Command.

INDUCTION, INDUCTANCE:

1) The process of loading a circuit or line to help reduce amplitude and frequency attenuation

2) The property of a circuit or circuit element to oppose a change in current flow; causes current changes to lag behind voltage changes. Inductance is measured in henrys.

INE:

Intelligent Network Element: Network element that can be provisioned from a remote OSS.

INFECTION:

The action a virus carries out when it enters a computer system or storage device.

INFO-TAINMENT:

A combination of traditional elements: Such as video, film, graphics, animation, music, audio, and text for the purposes of providing information and/or entertainment.

INFOMASTER:

A database and systems interface. A commercial W. U. produced computer system.

INFORMATION:

Any data that has been organized into meaningful context for a computer user(s)

INFORMATION BIT:

A data bit, an information component of a message or text, as opposed to an addressing, control (protocol) or error control bit.

INFORMATION ELEMENT:

In ATM, the portion of a signaling packet that carries information, such as addresses, used in the UNI specification

INFORMATION MANAGEMENT:

The process of defining, evaluating, protecting, and distributing data within an organization

INFORMATION MANAGEMENT SYSTEM/VIRTUAL STORAGE:

See IMS/VS

INFRARED:

A method of using infrared light to transmit data on a fiber optic medium, or open air transmission over short distances.

INFARED (IR):

Light that is beyond red in the color spectrum. While the light is not visible to the human eye, infrared transmitters and receivers can send and receive infrared signals. Electromagnetic waves whose frequency range is above that of microwaves, but below the visible spectrum.

INFRARED DATA ASSOCIATION (IrDA):

An industry organization of computer, component, and telecommunications vendors that establish the standards for infrared communication between computers and peripheral devices

INFRARED DEVICE:

A computer, or a computer peripheral such as a printer, that can communicate using infrared light.

INFRARED FILE TRANSFER:

Wireless file transfer between a computer and another computer or device using infrared light.

INFRARED PORT:

An optical port on a computer: Enables communication with other computers or devices by using infrared light, without cables. Infrared ports can be found on some portable computers, printers, and cameras.

INFRASTRUCTURE:

Identifies the underlying technology base (components) required to support a system.

INGRESS NOISE:

Over-the-air signals that are coupled inadvertently into the nominally closed coaxial cable distribution system; ingress noise is normally difficult to track down and intermittent in nature.

INITIAL MASTER:

A shared folder whose existing files and folders are replicated to other shared folders when replication is initially configured. After replication is complete, there is no initial master, since any of the replicas can accept changes and propagate the changes to the other replicas. The initial master then becomes another replica.

INITIALIZE:

In Disk Management, the process of detecting a disk or volume and assigning it a status (example: healthy) and a type (example: dynamic).

INJECTOR:

See: Dropper

INK:

An option that allows text to be entered in handwritten form: Instead of converting the handwritten text to typed text; the text is converted to an object and displayed exactly as it was written.

IN-LINE PROCESSING:

A method of processing in which each individual input action is completely processed and all pertinent records updated without previously having been batched or grouped. Each message received is stored, sent to a history tape and a record sent to a Journal tape prior to being processed for transmission to the addressed destination. Simultaneous messages are processed.

INLINING:

The practice of putting an IMG tag in a web page that calls for a graphic from another site. Many sites, particularly those offering free storage, now view this as bandwidth theft and block remote IMG calls from other sites to their site. It is bad netiquette and likely a copyright violation to display a graphic called from someone else's web page.

INOC:

Internet Network Operations Center: BBN group that in the early days of the Internet monitored and controlled the Internet core gateways (routers). INOC no longer exists in this form.

INPUT:

1) The data to be processed.

2) The sequence of events occurring on a specified input channel.

3) The device(s) used for inputting data into another device.

4) A signal that impresses a state (condition) on a device or logic element.

5) The process of transferring data from an external storage to an internal storage.

INPUT CIRCUIT:

A communications link: Between the processor and the input station (terminal) for transmission of data to the computer. See Input

INPUT DEVICE:

Normally refers to the devices used to input information into the computer (processor). Example: Card reader, Magnetic Tape, Disk, Optical Reader, etc.

INPUT-OUTPUT (I/O) DEVICES:

Devices used to get information into the computer or receive information from the computer. Also may be referred to as secondary storage. Discs, Tape stations, printers, etc. would be input/output devices.

INPUT-OUTPUT LIMITED:

Refers to a system condition in which the time for input and output operation exceeds the time for other operations.

INPUT/OUTPUT PORT (I/O) PORT:

A channel through which data is transferred between a device and the microprocessor: The port appears to the microprocessor as one or more memory addresses that it can use to send or receive data.

INQUIRY:

Inquiry-Response: A terminal (station) request for information from the data processor, which would be followed by a response, with the requested information, from the processor to the terminal.

INREQ:

Information Request

INSERTION LOSS:

A term used to identify the loss of signal power due to the connection of communications units possessing different impedance values.

INSERTION PORT:

The place where text will be inserted when typed. The insertion point usually appears as a flashing vertical bar in an applications window or in a dialog box.

INSTALL:

1) When referring to software: to add program files and folders to the hard disk and related data to the registry so that the software runs properly.

2) When referring to hardware: to physically connect the device to the computer, to load device drivers into the computer, and to configure device properties and settings.

INSTITUTE of ELECTRICAL and ELECTRONIC ENGINEERS (IEEE):

See IEEE

INSURED BURST:

In an ATM network, the largest burst of data above the insured rate that temporarily is allowed on a PVC and not tagged by the traffic policing function for dropping in the case of network congestion. The insured burst is specified in bytes or cells.

INSURED RATE:

Long-term data throughput stated in bits or cells per second that an ATM network commits to support under normal network conditions. The insured rate is 100 percent allocated; the entire amount is deducted from the total trunk bandwidth allotted to the path of the circuit.

INSURED TRAFFICE:

Traffic within the insured rate specified for an ATM PVC. This traffic should not be dropped by the network under normal network conditions.

INTAP:

Interoperability Technology Association for Information Processing: Technical organization that has the official charter to develop Japanese OSI profiles and conformance tests.

INTEGRATED CIRCUITS:

See IC

INTEGRATED DEVICE ELECTRONICS (IDE):

A type of disk drive interface where the controller electronics reside within the drive, eliminating the need for a separate adapter card. IDE offers advantages such as look-ahead caching to increase overall performance.

INTEGRATED IS-IS:

Routing protocol based on the OSI routing protocol IS-IS but with support for IP and other protocols. Integrated IS-IS implementations send only one set of routing updates, making it more efficient than two separate implementations; formerly called Dual IS-IS.

INTEGRATED SERVICES DIGITAL NETWORK (ISDN):

A Consultative Committee International Telephone and Telegraphy (CCITT) digital communication systems standard for transmitting voice, data, video and other digital communications.

A digital phone line used to provide higher bandwidth. ISDN in North America is typically available in two forms: Basic Rate Interface (BRI) consists of 2 B-channels at 64 kilobits per second (Kbps) and a D-channel at 16 Kbps; Primary Rate Interface (PRI) consists of 23 B-channels at 64 Kbps and a D-channel at 64 Kbps. An ISDN line must be installed by the phone company at both the calling site and the called site.

INTEGRATED SERVICES INTERNET:

IETF proposal for enhancing IP to allow it to support integrated or multimedia services, including traffic management mechanisms that closely match the traffic management mechanisms of ATM. Example: RSVP.

INTEGRATED SERVICE UNIT:

See ISU

INTEGRATED VOICE and DATA TERMINAL:

See IVDT

INTEL:

A microchip manufacturer and a sponsor, along with the Xerox Corp., of Ethernet

INTELSAT:

International Telecommunications Satellite Organization

INTELLIGENT / INTELLIGENCE:

A term used to describe a microprocessor controlled device able to perform sophisticated tasks relying on software, and therefore programmable.

INTELLIGENT PORT SELECTOR:

See data PBX

INTELLIGENT QoS MANAGEMENT SUITE:

Composed of Automatic Routing Management, Advanced CoS Management, Optimized Bandwidth Management, and Dynamic Buffer Management; formerly called Advanced Networking Features.

INTELLIGENT TDM:

See concentrator or multiplexing

INTELLIGENT TERMINAL:

A term used to describe a programmable microprocessor controlled device able to perform sophisticated tasks. The range of functions and degree of capability is not standardized and subject to wide discussion of what constitutes ‘intelligence’.

INTELLIGENT TIME DIVISION MULTIPLEXER:

See ITDM

INTERACTIVE TERMINAL INTERFACE:

See ITI

INTERAREA ROUTING:

Term used to describe routing between two or more logical areas.

INTERCEPT STORAGE:

A message protection operation: Normally under the control of operator personnel. Message traffic destined for an inoperable terminal, or for other abnormal conditions, would be held in temporary storage for future delivery.

INTERCHANGE CIRCUIT:

A circuit with an associated interface connector having designated connector pins for data, timing or control functions

INTERCONNECT:

A private network that connects nodes in a cluster

INTERCONNECT COMPANY/INDUSTRY:

An Interconnect company that provides communications terminal equipment for connection to telephone lines; an Interconnect Industry - Involved in the design, sales and service of equipment designed to connect to telephone lines.

INTER-EXCHANGE CARRIER:

See IEC

INTEREXCHANGE PLANT:

The facilities between switching centers

INTERFACE:

1) Interconnection between two devices, two applications, or a user and an application or device. 2) The connection between a MODEM and a terminal.

3) The connection between a communications controller and the computers I/O Channel.

4)  In routing terminology, a network connection.

5) In telephony, a shared boundary defined by common physical interconnection characteristics, signal characteristics, and interchanged signals.

6) Boundary between adjacent layers of the OSI model.

INTERFACE PROCESSOR:

1) Front End, Communications processor - A specialized communications device for interfacing computers and terminals to a network.

2) Any of a number of processor modules used in the Cisco 7000 series routers

INTERFERENCE:

Any unwanted noise, cross talk or spurious signals on a communications circuit (line) that acts to reduce the intelligibility of the desired information signal or speech.

INTERIOR GATEWAY ROUTING PROTOCOL:

IGP developed by Cisco to address the issues associated with routing in large, heterogeneous networks.

INTERMEDIATE DISTRIBUTION FRAME:

See IDF

INTER-MODULATION DISTORTION:

A form of distortion created by two analog frequencies and/or amplitude that causes a third unwanted frequency, which corrupts the data signal.

INTERNAL CLOCKING:

In synchronous communications a terminal or computer device is clocked internally when the bit-timing signal is provided from within the terminal or computer device, rather than from the MODEM.

INTERNAL NETWORK NUMBER:

A 4-byte hexadecimal number used for addressing and routing; the internal network number identifies a virtual network inside a computer. The Internal Network Number must be unique to the IPX (Integrated Packet Exchange) internetwork. Internal Network Number is also called virtual network number.

INTERNATIONAL ACCESS CODE:

Prefix digits required for placing an overseas telephone call.

INTERNATIONAL RECORD CARRIER (IRC):

A common carrier that provides international telephone lines (channels) for voice and data.

INTERNATIONAL STANDARDS ORGANIZATION: See ISO

INTERNATIONAL TELECOMMUNICATIONS UNION (ITU):

A United Nations agency: Regulates worldwide telecommunications procedures (standards) involving frequency allocation and radio regulations.

INTERNATIONAL TELEGRAPHS ALPHABET #1 (ITA 1); #2 (ITA 2); #3 (ITA 3); #4 (ITA 4); #5 (ITA 5):

World- standard CCITT version of the manual telegrapher's code; 5 unit code; 6 unit code; 7 unit code and 7 unit Tele-printer code.

INTERNATIONAL TEST AND MAINTENANCE CENTERS (ITMC):

The point of demarcation for international circuits often thought of as the end of domestic traffic and the beginning of international traffic.

INTERNET:

1) The worldwide network of computers, which allow communications via an agreed upon set of Internet protocols and accessible by all companies and individuals through an Internet Server.

2) ‘internet’ (Lower case i); Another version: When 2 or more networks are connected together it results in an internet, as in inter-national or inter-state.

3) Largest global inter-network, connecting tens of thousands of networks worldwide. Many leading-edge network technologies come from the Internet community. The Internet evolved in part from ARPANET; at one time, called the DARPA Internet. Not to be confused with the general term Internet.

INTERNET ADDRESS:

An address for a resource (service / provider) on the Internet that is used by Web browsers to locate Internet resources: An Internet address typically starts with a protocol name, followed by the name of the organization that maintains the site; then the suffix that identifies the kind / type of organization. For example: the address http://www.stanford.edu/ provides the following information:

http: Web server uses the Hypertext Transfer Protocol.

www: Site on the World Wide Web.

Stanford: Name of destination/resource

edu: Educational institution.

The Internet address is also called Uniform Resource Locator (URL).

INTERNET ENGINEERING TASK FORCE (IETF):

A community of network designers, operators, vendors, and researchers concerned with the evolution of Internet architecture and the smooth operation of the Internet. Technical work is performed by working groups organized by topic areas, such as routing, transport and security. Internet standards are developed through IETF Requests for Comments (RFC), which are a series of notes (input responses) that discuss many aspects of computing and computer communication, focusing on networking protocols, programs, and concepts.

INTERNET GROUP MANAGEMENT PROTOCOL (IGMP):

A protocol used by IP (Internet Protocol) hosts to report their multicast group memberships to any neighboring multicast routers.

INTERNET INFORMATION SERVICES (IIS):

Software services that support Web site creation, configuration, and management, along with other Internet functions: Internet Information Services include Network News Transfer Protocol (NNTP), File Transfer Protocol (FTP), and Simple Mail Transfer Protocol (SMTP).

INTERNET - Lower case i:

Any time two or more networks are connected together an Internet is formed, as in inter-national or inter-state.

INTERNET PROTOCOL (IP):

1) A protocol in the TCP/IP (Transmission Control Protocol/Internet Protocol) suite: Responsible for IP addressing, routing, and the fragmentation and reassembly of IP packets.

2) Internet Protocol, IPv4: Network layer for the TCP/IP protocol suite. Internet Protocol version 4 is a connectionless, best-effort packet switching protocol.

INTERNET PROTOCOL MULTICASTING:

The extension of a local area network multicasting technology to a TCP/IP (Transmission Control Protocol/Internet Protocol) network: Hosts send and receive multicast datagrams; the destination fields of which specify IP host group addresses rather than individual IP addresses. A host indicates that it is a member of a group by means of the Internet Group Management Protocol (IGMP).

INTERNET SERVICE PROVIDER (ISP):

A company that provides individuals or companies access to the Internet and the World Wide Web. An ISP provides a telephone number, a user name, a password, and other connection information so users can connect their computers to the ISP's computers. An ISP typically charges a monthly or hourly connection fee.

INTERNET TELEPHONY:

Generic term used to describe various approaches to running voice telephony over IP.

INTERNET - Upper case I:

The vast collection of inter-connected networks that are connected using the TCP/IP (Transmission Control Protocol / Internet Protocol) protocols: primarily evolved from the ARPANET in the late 60's and early 70's.

The Internet connects tens of thousands of independent networks into a vast global Internet and is probably the largest Wide Area Network in the world.

INTERNETWORK:

A series of network segments connected by bridges or gateways

INTERNETWORK ROUTER:

Refers to a Local Area Network (LAN) device used for communicating between sub networks, which transmits (routing) the messages to the correct sub network. Inter network routers function within the network layer of the OSI model.

INTERNETWORKING:

General term used to refer to the industry devoted to connecting networks together. The term can refer to products, procedures, and technologies.

INTER-NIC:

An organization that serves the Internet community by supplying user assistance, documentation, training, registration service for Internet domain names and other services; formerly called NIC.

INTEROFFICE TRUNK:

The telephone channel between two local central offices

INTEROPERABILITY:

The ability of systems and/or technology from various agencies and/or departments to work together

INTERRUPT:

A break in the normal flow of a systems (computer) routine such, that the normal flow can be resumed from the point of interrupt at a later time. An interrupt is usually caused by a signal from an external source requesting service.

INTERRUPTING EQUIPMENT:

The devices used to break the ringing generator's output into alternate ringing and silent periods and creating the busy and ring back tone pulses.

INTERTOLL TRUNK:

The telephone channel between toll offices in a different telephone exchange

INTER-SWITCH LINK (ISL):

Cisco-proprietary protocol that maintains VLAN information as traffic flows between switches and routers.

INTRA-AREA ROUTING:

Term used to describe routing within a logical area.

INTRANET:

A corporate network that uses an IP (Internet Protocol) network structure, together with a Web server and browser

INTRAOPERABILITY:

The ability of applications and computers within an agency or department to work together

INTRA-OFFICE TRUNK:

A trunk or path connection within the same central office

INTRUSION DETECTION:

Security service that monitor and analyzes system events for the purpose of determining and finding attempts to access system resources in an unauthorized manner.

INV:

Invalid Message: A Control Character: In AUTODIN the INV message character is transmitted when an unsolicited answer is received to transmitted data. It is sent each time an ACK1, ACK2, NAK, RM or WBT sequence is received when no answer is expected.

INVERSE ARP:

Inverse Address Resolution Protocol: Method of building dynamic routes in a network; allows an access server to discover the network address of a device associated with a virtual circuit.

INVERSE MULTIPLEXING:

Process whereby physical links are grouped to form a higher-bandwidth logical link whose rate is approximately the sum of the individual link rates.

I/O:

Input/Output

IOC:

Independent Operating Company: Independently owned company providing local telephone services to residential and business customers in a geographic area not served by an RBOC

IOCC:

Input / Output (I/O) Channel Controller

IONL:

Internal Organization of the Network Layer: OSI standard for the detailed architecture of the network layer. Basically, it partitions the network layer into sub-networks interconnected by convergence protocols, equivalent to internet working protocols, creating what the Internet community calls a catenet or an internet.

IOS:

Cisco system software that provides common functionality, scalability, and security for all products under the Cisco-Fusion architecture: Cisco IOS allows centralized, integrated, and automated installation and management of inter-networks while ensuring support for a wide variety of protocols, media, services, and platforms.

IP:

Internet Protocol:

1) A packet transmission standard for the transmission of data, voice, video and other information over the Internet.

2) Network layer protocol in the TCP/IP stack offering a connectionless inter-network service. IP provides features for addressing, type-of-service specification, fragmentation and reassembly, and security.

IP ADDRESS:

Internet Protocol Address: A 32-bit address assigned to hosts using TCP/IP. An IP address belongs to one of five classes (A, B, C, D, or E) and is written as 4 octets separated by periods (dotted decimal format). Each address consists of a network number, an optional sub-network number, and a host number. The network and sub-network numbers together are used for routing, and the host number is used to address an individual host within the network or sub-network. A subnet mask is used to extract network and sub-network information from the IP address. CIDR provides a new way of representing IP addresses and subnet masks.

Every computer on the Internet has a unique identifying number (address - 32 bit), such as 192.1.26.2.

IP DATAGRAM:

Fundamental unit of information passed across the Internet. Contains source and destination addresses along with data and a number of fields that define such things as the length of the datagram, the header checksum, and flags to indicate whether the datagram can be (or was) fragmented.

IP EXPLICIT PATH:

A list of IP addresses, each representing a node or a link in the explicit path

IP MULTICAST:

Routing technique that allows IP traffic to be propagated from one source to a number of destinations or from many sources to many destinations: Rather than sending one packet to each destination, one packet is sent to a multicast group identified by a single IP destination group address.

IP MULTICAST HEARTBEAT:

Users of the multicast routing feature need a way to monitor the health of multicast delivery and be alerted when the delivery fails to meet certain parameters.

IP MULTICAST MULTILAYER SWITCHING (MLS):

Feature that provides high-performance, hardware-based, Layer 3 switching of IP multicast traffic for routers connected to Catalyst 5000 series LAN switches. An IP multicast flow is a unidirectional sequence of packets between a multicast source and the members of a destination multicast group. Flows are based on the IP address of the source device and the destination IP multicast group address. IP multicast MLS switches IP multicast data packet flows between IP subnets using advanced, application-specific integrated circuit (ASIC) switching hardware, thereby off-loading processor-intensive, multicast packet routing from network routers. The packet forwarding function is moved onto the connected Layer 3 switch whenever a supported path exists between a source and members of a multicast group. Packets that do not have a supported path to reach their destinations still are forwarded by software by routers. Protocol Independent Multicast (PIM) is used for route determination.

IP NUMBER:

Internet Protocol Number: Sometimes called a dotted quad. A unique number consisting of 4 parts separated by dots, e.g. 185.123.355.4

Every computer that is on the Internet has a unique IP number. If a computer does not have an IP number, it is not really connected directly to the Internet. Many computers (especially servers) also have one or more Domain Names that are easier for people to remember.

IP over ATM:

Suite used to send IP datagram packets between nodes on the Internet.

IP PRECEDENCE:

A 3-bit value in the Type of Service (TOS) byte used for assigning precedence to IP packets

IP SECURITY (IP-Sec):

Internet Protocol Security: A value used in combination with an algorithm to encrypt or decrypt data. Key settings for IP security are configurable to provide greater security.

IP SPOOFING:

IP spoofing attack occurs when an attacker outside the private network pretends to be a trusted user either by using an IP address that is within the range of IP addresses for the network or by using an authorized external IP address that is trusted. Should an attacker get access to the IP-Sec security parameters, that attacker can masquerade as the remote user authorized to connect to the network.

IP TELEPHONY:

The transmission of voice and fax phone calls over data networks that uses the Internet Protocol (IP). IP telephony involves the transformation of the circuit-switched telephone network to a packet-based network that deploys voice-compression algorithms and flexible and sophisticated transmission techniques, and uses only a fraction of traditional digital telephony's usual bandwidth.

IP VIDEO:

An encoding mechanism: Used to transmit motion video clips over an IP (Internet Protocol) network.

IPv4:

Internet Protocol, version 4: The most widely used version of the Internet Protocol (IP); part of (Transmission Control Protocol / Internet Protocol) TCP/IP.

IPv4 allows for a theoretical maximum of approximately four billion IP Numbers, but the actual number is far less due to inefficiencies in the way blocks of numbers are handled by networks. The gradual adoption of IPv6 should solve this problem.

IPv6:

Internet Protocol, version 6: The successor to IPv4; already deployed in some cases and gradually spreading. IPv6 provides a huge number of available IP Numbers, over a sextillion addresses. IPv6 allows every device on the planet to have its own IP Number.

IP VOICE:

A technology that enables voice traffic to be transmitted over any network that uses IP (Internet Protocol); including LAN, WAN, and the Internet.

IPC:

Inter-process Communications: This mechanism makes it possible to create large systems that are complex in function, yet simple and streamlined in design.

IPCP:

IP Control Protocol: Protocol that establishes and configures IP over PPP.

IPL:

1) Inter-Processor Link

2) Initial Processor Load (Program reload)

IPSEC:

IP Security: A framework of open standards that provides data confidentiality, data integrity, and data authentication between participating peers. IP-Sec provides these security services at the IP layer. IP-Sec uses IKE to handle the negotiation of protocols and algorithms based on local policy and to generate the encryption and authentication keys to be used by IP-Sec. IP-Sec can protect one or more data flows between a pair of hosts, between a pair of security gateways, or between a security gateway and a host.

IPSO:

IP Security Option:U.S. government specification that defines an optional field in the IP packet header that defines hierarchical packet security levels on a per interface basis.

IPX:1) Integrated Packet Exchange: Example:  Stratacom's Packet - switch for public and private T1 networks.

2) Inter-network Packet Exchange: NetWare network layer 3 Protocol used for transferring data from servers to workstations. IPX is similar to IP and XNS.

IPXCP:

IPX Control Protocol: Protocol that establishes and configures IPX over PPP.

IPX/SPX:

Integrated Packet Exchange / Sequenced Packet Exchange: Transport protocols used in Novell NetWare networks, which together correspond to the combination of TCP and IP in the TCP/IP (Transmission Control Protocol/Internet Protocol) protocol suite. Windows implements IPX through NWLink.

IPXWAN:

IPX Wide-Area Network: Protocol that negotiates end-to-end options for new links. When a link comes up, the first IPX packets sent across are IPXWAN packets negotiating the options for the link. When the IPXWAN options are determined successfully, normal IPX transmission begins.

IR:

1) Intermediate Reach: The distance specification for optical systems that operate effectively from 3 to 20 km (1.8 to 12.5 mi).

2) Internet Registry: IR was delegated the responsibility of network address and autonomous system identifiers from the IANA, which has the discretionary authority to delegate portions of its responsibility.

IRB:

Integrated Routing and Bridging: Integrated Services Digital Network (ISDN) User Part; an upper-layer application supported by SS7 for connection set up and tear down.

IRC:

1) Internet Relay Chat: World-wide ‘party line’ protocol that allows one to converse with others in real time. IRC is structured as a network of servers, each of which accepts connections from client programs, one per user.

2) See International Record Carrier

IRDP:

ICMP Router Discovery Protocol: Protocol that enables a host to determine the address of a router that it can use as a default gateway. Similar to ES-IS but IRDP is used with IP.

IRN:

Intermediate Routing Node: In SNA, a sub-area node with intermediate routing capability.

IRR:

A RAS message sent as an information request.

IRSG:

Internet Research Steering Group: Group that is part of the Internet Architecture Board (IAB) and oversees the activities of the Internet Research Task Force (IRTF).

IRTF:

Internet Research Task Force: Community of network experts that overviews Internet-related research topics. The IRTF is governed by the Internet Research Steering Group (IRSG) and is considered a subsidiary of the Internet Architecture Board (IAB).

I-S/A AMPE:

The Inter-Service/Agency Automated Message Processing Exchange (I-S/A AMPE) system was one of several failed attempts to replace AUTODIN.

IS:

1) Intermediate System: Routing node in an OSI network.

2. In-Service: Telecommunications: Entity is fully operational and capable of providing service to a requesting entity.

ISA:

1) Intelligent Storage Architecture: EMC uses Intelligent Storage Architecture to consolidate information management functions including backup/restore, disaster recovery, migration, and information sharing into a single enterprise storage system. This provides a single consistent platform from which to manage, access, and share information.

2) Industry-Standard Architecture: 16-bit bus used for Intel-based personal computers.

ISA EXPANSION SLOT:

Intelligent Storage Architecture: A connection socket for a peripheral designed to the Industry Standard Architecture (ISA) on a computer motherboard.

ISAKMP:

Internet Security Association and Key Management Protocol: Internet IP-Sec protocol (RFC 2408) that negotiates, establishes, modifies, and deletes security associations. It also exchanges key generation and authentication data, key establishment protocol, encryption algorithm, or authentication mechanism.

IS-IS:

Intermediate System-to-Intermediate System: OSI link-state hierarchical routing protocol based on DEC-net Phase V routing, where IS-IS(s) (routers) exchange routing information based on a single metric to determine network topology.

ISDL:

ISDN Digital Subscriber Line: Uses ISDN transmission technology to transmit data at 128 kbps through an IDSL MODEM connected to a Router.

ISDN:
Integrated Services Digital Network: ISDN specifications provide for wide-bandwidth digital transmission using the public switched telephone network; allows up to 56 kbps of data bandwidth on a telephone line that is also used for voice transmission or up to 128 kbps if the line is only used for data. ISDN is unique among WAN services in that it provides access both to the circuit switched public telephone network and to packet switched services, such as X.25 and frame relay.

ISL:

Inter-Switch Link: Cisco-proprietary protocol that maintains VLAN information as traffic flows between switches and routers.

ISM:

Inter-network Status Monitor

ISO:

International Standards Organization: The International voluntary standards organization that coordinates with the Consultative Committee International Telephone and Telegraphy (CCITT) in the development of communications standards. ISO developed the Open Systems Interconnection (OSI) model and OSI communications protocol. Membership includes other international organizations, with ANSI being the American representative.

ISOCHRONOUS:

Refers to a form of data transmission in which the transmitter would use a synchronous clock when sending messages, while the receiving device does not use a synchronous clock, and detects message characters by framing with start/stop bits, similar to asynchronous transmission.

ISO 9000:

Set of international quality-management standards defined by ISO. The standards, which are not specific to any country, industry, or product, allow companies to demonstrate that they have specific processes in place to maintain an efficient quality system.

ISO 3309:

HDLC procedures developed by ISO: ISO 3309:1979 specifies the HDLC frame structure for use in synchronous environments. ISO 3309:1984 specifies proposed modifications to allow the use of HDLC in asynchronous environments as well.

ISOC:

Internet Society: International nonprofit organization, founded in 1992, that coordinates the evolution and use of the Internet. In addition, ISOC delegates’ authority to other groups related to the Internet, such as the IAB.

ISOCHRONOUS TRANSMISSION:

Asynchronous transmission over a synchronous data link: Isochronous signals require a constant bit rate for reliable transport.

ISODE:

ISO Development Environment: Large set of libraries and utilities used to develop upper-layer OSI protocols and applications.

ISP:

Internet Service Provider: A company that provides a connection to the Internet via either a Dial-up Connection or a Direct Connection

ISR:

Intermediate Session Routing: Initial routing algorithm used in APPN. ISR provides node-to-node connection-oriented routing. Network outages cause sessions to fail because ISR cannot provide non-disruptive rerouting around a failure. ISR was replaced by High-Performance Routing (HPR).

ISSI:

Inter-Switching System Interface: Standard interface between Switched Multi-megabit Data Service (SMDS) switches.

IST:

Inter-switch Trunks (Trunks): The channels connecting the AUTODIN Switching Centers (ASC). The Trunk channels are high speed, fully sequentially controlled and secure.

ISUP:

ISDN User Part: SS7 protocol layer that defines the protocol used to prepare, manage, and release trunks that carry voice and data between calling and called parties.

ISUP CONSOLE:

ISDN User Part Console: When the Circuit Inter-working software (CKTINT) module is running, this process provides management functions for circuits and circuit groups for the SS7 application software in the Cisco VCO/4K.

ISU:

Integrated Service Unit: A device designed to combine the functions of a Data Service Unit (DSU) and a Channel Service Unit (CSU).

IT:

Information Technology: A general term referring to the field of Information Technology; includes anything from computer hardware to programming and network management. Most medium and large size companies have IT Departments.

ITA#2:

International Telegraphic Alphabet, version # 2: American Version teletypewriter 5-bit code, also known as the Baudot Code.

ITCM:

Integrated Telephony Cable Modem: A Data-over-Cable Service Interface Specification (DOCSIS), Cable MODEM (CM) that enables subscriber Voice over Internet Protocol (VoIP) services

ITDM:

Intelligent Time Division Multiplexer: A device designed to assign time slots on demand, rather than on a fixed sub channel basis.

ITI:

Interactive Terminal Interface: A term used in packet switching networks to define a Packet Assembler Dis-assembler (PAD) supporting network accessed by asynchronous terminals.

ITMC:

See International Test and Maintenance Centers

TU:

International Telecommunication Union: An organization established by the United Nations to set international telecommunications standards and to allocate frequencies for specific uses.

ITU-R:

International Telecommunications Union: International telecommunications standards-setting body, specializing in radio-spectrum usage. Originally CCIR

ITU-T:

International Telecommunication Union - Telecommunication Standardization Sector: International body that develops worldwide standards for telecommunications technologies. The ITU-T carries out the functions of the former CCITT.

ITU LAP-B:

Link Access Procedure Balanced: Internal computer system components

IV:

Initialization Value: Input parameter that sets the starting state of a cryptographic algorithm or mode.

IVDT:

Integrated Voice and Data Terminal: A dual function device incorporating both a data terminal keyboard, display and voice telephone.

IVR:

Interactive Voice Response: Term used to describe systems that provide information in the form of recorded messages over telephone lines in response to user input in the form of spoken words or DTMF signaling. Examples include banks that allow you to check your balance from any telephone and automated stock quote systems.

IXC:Inter-Exchange Carrier: Common carrier providing long distance connectivity between LATA(s). Example: AT&T, MCI, and Sprint, but several hundred IXC(s) offer long distance service in the United States.