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10Base2

A physical layer communications specification for 10Mbps, baseband data transmission over a coaxial cable (Thinnet) with a maximum cable segment length of 200 meters. [Source: RFC1983]

10Base5

A physical layer communications specification for 10Mbps, baseband data transmission over a coaxial cable (Thicknet) with a maximum cable segment length of 500 meters. [Source: RFC1983]

10BaseF

A physical layer communications specification for 10Mbps, baseband data transmission over a fiber-optic cable. [Source: RFC1983]

10BaseT

A physical layer communications specification for 10Mbps, baseband data transmission over a twisted-pair copper wire. See also: Ethernet, twisted pair. [Source: RFC1983]

802.11

The set of IEEE Working Groups and subsequent standards for the definition of wireless LAN protocols. The Physical Layer (air interface) incorporates Spread Spectrum techniques to avoid detection, interception and interference between devices. The results so far are 802.11b, which has a data rate of 11Mbit/s and uses the 2.4GHz radio band, then 802.11a which has a data rate of 54Mbit/s and uses the 5GHz radio band, so it is not inherently interoperable with 802.11b. Subsequently 802.11g has a data rate of greater than 20MBit/s with the 2.4GHz range, so there is scope for interworking with 802.11b devices. Then 802.11h enhances the 802.11a standard to select frequencies and trim power output to avoid interference with HIPERLAN devices in Europe which use the same 5GHz band. The 2.4GHz and 5GHz radio bands are licence exempt so are attractive to general users.

There is a built-in security method, Wired Equivalent Privacy (WEP) within 802.11b standard, but there is an initial move to use 802.1x security mechanisms before 802.11i is fully developed to enhance security and authentication mechanisms (ongoing at March 2003). See also: 802.x, Bluetooth, HIPERLAN, IEEE, Spread Spectrum, Wired Equivalent Privacy, Wireless Local Area Network.

802.x

The set of IEEE Working Groups and subsequent standards for the definition of fixed and wireless LAN and MAN protocols. See also: 802.11, Bluetooth, IEEE, Wireless Local Area Network.

822

See: RFC 822

:-)

This odd symbol is one of the ways a person can portray "mood" in the very flat medium of computers--by using "smiley faces". This is "metacommunication", and there are literally hundreds of such symbols, from the obvious to the obscure. This particular example expresses "happiness". Don't see it? Tilt your head to the left 90 degrees. Smiles are also used to denote sarcasm. [Source: ZEN]

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A

Address record for a host of given name in Domain Name Service.

AbMAN

Aberdeen Metropolitan Area Network.

abstract syntax

A description of a data structure that is independent of machine- oriented structures and encodings. [Source: RFC1208]

Abstract Syntax Notation One (ASN.1)

The language used by the OSI protocols for describing abstract syntax. This language is also used to encode SNMP packets. ASN.1 is defined in ISO documents 8824.2 and 8825.2. See also: Basic Encoding Rules. [Source: RFC1392]

Acceptable Use Policy (AUP)

Many transit networks have policies which restrict the use to which the network may be put. For example, some networks may only be used for non-commercial purposes. Some AUPs limit the type of material which can be made available to the public (e.g., pornographic material). Enforcement of AUPs varies with the network. See also: netiquette. [Source: RFC1983]

Access Control List (ACL)

Most network security systems operate by allowing selective use of services. An Access Control List is the usual means by which access to, and denial of, services is controlled. It is simply a list of the services available, each with a list of the hosts permitted to use the service. [Source: RFC1392]

ACK

See: Acknowledgment

acknowledgment (ACK)

A type of message sent to indicate that a block of data arrived at its destination without error. See also: Negative Acknowledgement. [Source: NNSC]

ACL

See: Access Control List

ACSE

Association Control Service Element. The method used in OSI for establishing a call between two applications. Checks the identities and contexts of the application entities, and could apply an authentication security check. [Source: RFC1208]

AD

See: Administrative Domain

address

There are four types of addresses in common use within the Internet. They are email address; IP, internet or Internet address; hardware or MAC address; and URL. See also: email address, IP address, internet address, MAC address, Uniform Resource Locator. [Source: RFC1983]

address mask

A bit mask used to identify which bits in an IP address correspond to the network and subnet portions of the address. This mask is often referred to as the subnet mask because the network portion of the address (i.e., the network mask) can be determined by the encoding inherent in an IP address. See also: Classless Inter- domain Routing. [Source: RFC1983]

address resolution

Conversion of a network-layer address (e.g. IP address) into the corresponding physical address (e.g., MAC address). See also: IP address, MAC address. [Source: RFC1983]

Address Resolution Protocol (ARP)

Used to dynamically discover the low level physical network hardware address that corresponds to the high level IP address for a given host. ARP is limited to physical network systems that support broadcast packets that can be heard by all hosts on the network. It is defined in RFC 826. See also: proxy ARP, Reverse Address Resolution Protocol. [Source: RFC1983]

ADMD

Administration Management Domain. An X.400 Message Handling System public service carrier. Examples:- MCImail and ATTmail in the U.S., British Telecom Gold400mail in the U.K. The ADMDs in all countries worldwide together provide the X.400 backbone. See PRMD. [Source: RFC1208]

Administrative Domain (AD)

A collection of hosts and routers, and the interconnecting network(s), managed by a single administrative authority. [Source: RFC1392]

administrivia

Administrative tasks, most often related to the maintenance of mailing lists, digests, news gateways, etc.

Advanced Research Projects Agency (ARPA)

An agency of the U.S. Department of Defense responsible for the development of new technology for use by the military. ARPA (formerly known as DARPA, nee ARPA) was responsible for funding much of the development of the Internet we know today, including the Berkeley version of Unix and TCP/IP. [Source: NNSC]

Advanced Research Projects Agency Network (ARPANET)

A pioneering longhaul network funded by ARPA. It served as the basis for early networking research, as well as a central backbone during the development of the Internet. The ARPANET consisted of individual packet switching computers interconnected by leased lines. See also: Advanced Research Projects Agency. [Source: FYI4]

agent

In the client-server model, the part of the system that performs information preparation and exchange on behalf of a client or server application. [Source: RFC1208]

alias

A name, usually short and easy to remember, that is translated into another name, usually long and difficult to remember. [Source: RFC1392]

American National Standards Institute (ANSI)

This organization is responsible for approving U.S. standards in many areas, including computers and communications. Standards approved by this organization are often called ANSI standards (e.g., ANSI C is the version of the C language approved by ANSI). ANSI is a member of ISO. See also: International Organization for Standardization. [Source: NNSC]

American Standard Code for Information Interchange (ASCII)

A standard character-to-number encoding widely used in the computer industry. See also: EBCDIC. [Source: RFC1392]

anonymous FTP

Anonymous FTP allows a user to retrieve documents, files, programs, and other archived data from anywhere in the Internet without having to establish a userid and password. By using the special userid of "anonymous" the network user will bypass local security checks and will have access to publicly accessible files on the remote system. See also: archive site, File Transfer Protocol, World Wide Web. [Source: RFC1983]

ANSI

See: American National Standards Institute

AOW

Asia and Oceania Workshop. One of the three regional OSI Implementors Workshops, equivalent to OIW and EWOS.

API

See: Application Program Interface

Appletalk

A networking protocol developed by Apple Computer for communication between Apple Computer products and other computers. This protocol is independent of the network layer on which it is run. Current implementations exist for Localtalk, a 235Kb/s local area network; and Ethertalk, a 10Mb/s local area network. [Source: NNSC]

application

A program that performs a function directly for a user. FTP, mail and Telnet clients are examples of network applications. [Source: RFC1392]

application layer

The top layer of the network protocol stack. The application layer is concerned with the semantics of work (e.g., formatting electronic mail messages). How to represent that data and how to reach the foreign node are issues for lower layers of the network. [Source: MALAMUD]

Application Program Interface (API)

A set of calling conventions which define how a service is invoked through a software package. [Source: RFC1208]

archie

A system to automatically gather, index and serve information on the Internet. The initial implementation of archie provided an indexed directory of filenames from all anonymous FTP archives on the Internet. Later versions provide other collections of information. See also: archive site, Gopher, Prospero, Wide Area Information Servers. [Source: RFC1392]

archive site

A machine that provides access to a collection of files across the Internet. For example, an anonymous FTP archive site provides access to arcived material via the FTP protocol. WWW servers can also serve as archive sites. See also: anonymous FTP, archie, Gopher, Prospero, Wide Area Information Servers, World Wide Web. [Source: RFC1392]

ARP

See: Address Resolution Protocol

ARPA

See: Defense Advanced Research Projects Agency

ARPANET

See: Advanced Research Projects Agency Network

AS

See: Autonomous System

ASCII

See: American Standard Code for Information Interchange

ASN.1

See: Abstract Syntax Notation One

assigned numbers

The RFC [STD2] which documents the currently assigned values from several series of numbers used in network protocol implementations. This RFC is updated periodically and, in any case, current information can be obtained from the Internet Assigned Numbers Authority (IANA). If you are developing a protocol or application that will require the use of a link, socket, port, protocol, etc., please contact the IANA to receive a number assignment. See also: Internet Assigned Numbers Authority, STD. [Source: STD2]

asynchronous

Transmission by individual bytes, not related to specific timing on the transmitting end.

Asynchronous Transfer Mode (ATM)

A standard which defines high-load, high-speed (1.544Mbps through 1.2Gbps), fixed-size packet (cell) switching with dynamic bandwidth allocation. ATM is also known as "fast packet." [Source: RFC1983]

ATM

See: Asynchronous Transfer Mode

AUP

See: Acceptable Use Policy

attribute

The form of information items provided by the X.500 Directory Service. The directory information base consists of entries, each containing one or more attributes. Each attribute consists of a type identifier together with one or more values. Each directory Read operation can retrieve some or all attributes from a designated entry. [Source: RFC1208]

AUSCERT

Australian Computer Emergency Response Team.

authentication

The verification of the identity of a person or process. [Source: MALAMUD]

auto-magic

Something which happens pseudo-automatically, and is usually too complex to go into any further than to say it happens ``auto-magically.''

Autonomous System (AS)

Internet (TCP/IP) terminology for a collection of routers under a single administrative authority using a common Interior Gateway Protocol (IGP) for routing packets. See subnetwork. [Source: RFC1392]

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backbone

The top level in a hierarchical network. Stub and transit networks which connect to the same backbone are guaranteed to be interconnected. See also: stub network, transit network. [Source: RFC1392]

bandwidth

Technically, the difference, in Hertz (Hz), between the highest and lowest frequencies of a transmission channel. However, as typically used, the amount of data that can be sent through a given communications circuit. [Source: RFC1392]

bang path

A series of machine names used to direct electronic mail from one user to another, typically by specifying an explicit UUCP path through which the mail is to be routed. See also: email address, mail path, UNIX-to-UNIX CoPy. [Source: RFC1392]

BAR

Backbone Access Router between a MAN and the JANET backbone.

baseband

A transmission medium through which digital signals are sent without complicated frequency shifting. In general, only one communication channel is available at any given time. Ethernet is an example of a baseband network. See also: broadband, Ethernet. [Source: NNSC]

Basic Encoding Rules (BER)

Standard rules for encoding data units described in ASN.1. Sometimes incorrectly lumped under the term ASN.1, which properly refers only to the abstract syntax description language, not the encoding technique. See also: Abstract Syntax Notation One. [Source: NNSC]

BBS

See: Bulletin Board System

BCNU

Be Seein' You [Source: RFC1392]

BCP

The newest subseries of RFCs which are written to describe Best Current Practices in the Internet. Rather than specifying a protocol, these documents specify the best ways to use the protocols and the best ways to configure options to ensure interoperability between various vendors' products. BCPs carry the endorsement of the IESG. See also: Request For Comments, Internet Engineering Steering Group. [Source: RFC1983]

BDP

Netscape's Browser Distribution Program.

BECTa

British Educational Communications and Technology Agency.

BER

See: Basic Encoding Rules

Berkeley Internet Name Domain (BIND)

Implementation of a DNS server developed and distributed by the University of California at Berkeley. Many Internet hosts run BIND, and it is the ancestor of many commercial BIND implementations. See also: Domain Name System. [Source: RFC1983]

Berkeley Software Distribution (BSD)

Implementation of the UNIX operating system and its utilities developed and distributed by the University of California at Berkeley. "BSD" is usually preceded by the version number of the distribution, e.g., "4.3 BSD" is version 4.3 of the Berkeley UNIX distribution. Many Internet hosts run BSD software, and it is the ancestor of many commercial UNIX implementations. [Source: NNSC]

BGP

See: Border Gateway Protocol

big-endian

A format for storage or transmission of binary data in which the most significant bit (or byte) comes first. The term comes from "Gulliver's Travels" by Jonathan Swift. The Lilliputians, being very small, had correspondingly small political problems. The Big-Endian and Little-Endian parties debated over whether soft- boiled eggs should be opened at the big end or the little end. See also: little-endian. [Source: RFC1208]

binary

11001001

BIND

See: Berkeley Internet Name Domain

Birds Of a Feather (BOF)

A Birds Of a Feather (flocking together) is an informal discussion group. It is formed, often ad hoc, to consider a specific issue and, therefore, has a narrow focus. See also: Working Group. [Source: RFC1392]

Bitnet

Because It's Time NETwork. An academic computer network that provided interactive electronic mail and file transfer services, using a store-and-forward protocol, based on IBM Network Job Entry protocols. Bitnet-II encapsulated the Bitnet protocol within IP packets and depended on the Internet to route them. [Source: RFC1208]

Blue Book

the document describing a File Transfer Protocol used in the UK academic and research community which was implemented on a wide range of computers and which allowed file transfers between dissimilar computers. Also known as Network Independent File Transfer Protocol (NIFTP). Now mostly superseded by Internet protocols (see FTP).

Bluetooth

An IEEE standard 802.15.1 for short range (up to 10m) wireless links between mobile computers, phones and other portable peripheral devices. This uses the 2.4GHz band with a data rate of 1Mbit/s. Work was in progress in March 2002 on a High Rate (20Mbit/s or greater) version 802.15.3 in the same 2.4GHz band. Also known as Personal Area Network. See also: Wireless Local Area Network.

BNC

Bayonet Nut Connector. A connector used on coaxial cables such as 10Base2 Ethernet.

BOC

Bell Operating Company. More commonly referred to as RBOC for Regional Bell Operating Company. The local telephone company in each of the seven U.S. regions. [Source: RFC1208]

BOF

See: Birds Of a Feather

BOOTP

The Bootstrap Protocol, described in RFC 951 and RFC 1084, is used for booting diskless nodes. Updated in RFC 1395 and RFC 1497 and superseded by DHCP. See also: Reverse Address Resolution Protocol, Dynamic Host Configuration Protocol. [Source: RFC1392]

Border Gateway Protocol (BGP)

The Border Gateway Protocol is an exterior gateway protocol defined in RFC 1267 and RFC 1268. It's design is based on experience gained with EGP, as defined in STD 18, RFC 904, and EGP usage in the NSFNET Backbone, as described in RFC 1092 and RFC 1093. See also: Exterior Gateway Protocol. [Source: RFC1392]

bounce

The return of a piece of mail because of an error in its delivery. [Source: ZEN]

bridge

A device which forwards traffic between network segments based on datalink layer information. These segments would have a common network layer address. See also: gateway, router. [Source: RFC1392]

broadband

A transmission medium capable of supporting a wide range of frequencies. It can carry multiple signals by dividing the total capacity of the medium into multiple, independent bandwidth channels, where each channel operates only on a specific range of frequencies. See also: baseband. [Source: RFC1392]

broadcast

A special type of multicast packet which all nodes on the network are always willing to receive. See also: multicast, unicast. [Source: RFC1392]

broadcast storm

An incorrect packet broadcast onto a network that causes multiple hosts to respond all at once, typically with equally incorrect packets which causes the storm to grow exponentially in severity. [Source: RFC1392] See also: Ethernet meltdown.

brouter

A device which bridges some packets (i.e., forwards based on datalink layer information) and routes other packets (i.e., forwards based on network layer information). The bridge/route decision is based on configuration information. See also: bridge, router. [Source: RFC1392]

BSD

See: Berkeley Software Distribution

BTW

An abbreviation for ``By The Way''.

Bulletin Board System (BBS)

A computer, and associated software, which typically provides electronic messaging services, archives of files, and any other services or activities of interest to the bulletin board system's operator. Although BBS's have traditionally been the domain of hobbyists, an increasing number of BBS's are connected directly to the Internet, and many BBS's are currently operated by government, educational, and research institutions. See also: Electronic Mail, Internet, Usenet. [Source: NWNET]

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C&NL MAN

Cumbra and North Lancashire Metropolitan Area Network.

Campus Wide Information System (CWIS)

A CWIS makes information and services publicly available on campus via kiosks, and makes interactive computing available via kiosks, interactive computing systems and campus networks. Services routinely include directory information, calendars, bulletin boards, databases. [Source: RFC1392]

catenet

A network in which hosts are connected to networks with varying characteristics, and the networks are interconnected by gateways (routers). The Internet is an example of a catenet. See IONL. [Source: RFC1208]

CCIRN

See: Coordinating Committee for Intercontinental Research Networks

CCITT

See: Comite Consultatif International de Telegraphique et Telephonique

CCR

Commitment, Concurrency, and Recovery. An OSI application service element used to create atomic operations across distributed systems. Used primarily to implement two-phase commit for transactions and nonstop operations. [Source: RFC1208]

CERNET

China Education and Research Network.

CERT

See: Computer Emergency Response Team

CFV (Call For Votes)

Initiates the voting period for a Usenet newsgroup. At least one (occasionally two or more) email address is customarily included as a repository for the votes.

checksum

A computed value which is dependent upon the contents of a packet. This value is sent along with the packet when it is transmitted. The receiving system computes a new checksum based upon the received data and compares this value with the one sent with the packet. If the two values are the same, the receiver has a high degree of confidence that the data was received correctly. [Source: NNSC]

CHEST

Combined Higher Education Software Team negociates agreements with suppliers, especially for site licences, for the education community, thus making it the educational shop window for purchases of software, data, information, traning materials and other IT related products.

CIDR

See: Classless Inter-domain Routing

circuit switching

A communications paradigm in which a dedicated communication path is established between two hosts, and on which all packets travel. The telephone system is an example of circuit switched network. See also: connection-oriented, connectionless, packet switching. [Source: RFC1392]

ClariNews

The fee-based Usenet newsfeed available from ClariNet Communications.

Classless Inter-domain Routing (CIDR)

A proposal, set forth in RFC 1519, to allocate IP addresses so as to allow the addresses to be aggregated when advertised as routes. It is based on the elimination of intrinsic IP network addresses; that is, the determination of the network address based on the first few bits of the IP address. See also: IP address, network address, supernet. [Source: RFC1983]

ClydeNet

River Clyde area's Metropolitan Area Network.

client

A computer system or process that requests a service of another computer system or process. A workstation requesting the contents of a file from a file server is a client of the file server. See also: client-server model, server. [Source: NNSC]

client-server model

A common way to describe the paradigm of many network protocols. Examples include the name-server/name-resolver relationship in DNS and the file-server/file-client relationship in NFS. See also: client, server, Domain Name System, Network File System. [Source: RFC1392]

CLNP

Connectionless Network Protocol. The OSI protocol for providing the OSI Connectionless Network Service (datagram service). CLNP is the OSI equivalent to Internet IP, and is sometimes called ISO IP. [Source: RFC1208]

CLTP

Connectionless Transport Protocol. Provides for end-to-end Transport data addressing (via Transport selector) and error control (via checksum), but cannot guarantee delivery or provide flow control. The OSI equivalent of UDP. [Source: RFC1208]

CMIP

Common Management Information Protocol. The OSI network management protocol. [Source: RFC1208]

CMOT

CMIP Over TCP. An effort to use the OSI network management protocol to manage TCP/IP networks. [Source: RFC1208]

CNAME

Canonical Name (alternative name for a host) in Domain Name Service.

CNI

See: Coalition for Networked Information

Coalition for Networked Information (CNI)

A consortium formed by American Research Libraries, CAUSE, and EDUCOM (no, they are not acronyms) to promote the creation of, and access to, information resources in networked environments in order to enrich scholarship and enhance intellectual productivity. [Source: RFC1392]

Coloured Books

set of standard protocols and recommendations for the different aspects of networking software developed and used by the UK academic and research community. Now superseded by Internet protocols. See also protocol.

Comite Consultatif International de Telegraphique et Telephonique

(CCITT) This organization is part of the United National International Telecommunications Union (ITU) and is responsible for making technical recommendations about telephone and data communications systems. Every four years CCITT holds plenary sessions where they adopt new standards; the most recent was in 1992. Recently, the ITU reorganized and CCITT was renamed the ITU-T. See also: International Telecommunications Union - Telecommunications. [Source: RFC1983]

Computer Emergency Response Team (CERT)

The CERT was formed by DARPA in November 1988 in response to the needs exhibited during the Internet worm incident. The CERT charter is to work with the Internet community to facilitate its response to computer security events involving Internet hosts, to take proactive steps to raise the community's awareness of computer security issues, and to conduct research targeted at improving the security of existing systems. CERT products and services include 24-hour technical assistance for responding to computer security incidents, product vulnerability assistance, technical documents, and tutorials. In addition, the team maintains a number of mailing lists (including one for CERT Advisories), and provides an anonymous FTP server, at "cert.org", where security-related documents and tools are archived. The CERT may be reached by email at "cert@cert.org" and by telephone at +1-412-268-7090 (24-hour hotline). See also: Advanced Research Projects Agency, worm. [Source: RFC1392]

congestion

Congestion occurs when the offered load exceeds the capacity of a data communication path. [Source: RFC1392]

connection-oriented

The data communication method in which communication proceeds through three well-defined phases: connection establishment, data transfer, connection release. TCP is a connection-oriented protocol. See also: circuit switching, connectionless, packet switching, Transmission Control Protocol. [Source: RFC1392]

connectionless

The data communication method in which communication occurs between hosts with no previous setup. Packets between two hosts may take different routes, as each is independent of the other. UDP is a connectionless protocol. See also: circuit switching, connection-oriented, packet switching, User Datagram Protocol. [Source: RFC1392]

Coordinating Committee for Intercontinental Research Networks (CCIRN)

A committee that includes the United States FNC and its counterparts in North America and Europe. Co-chaired by the executive directors of the FNC and the European Association of Research Networks (RARE), the CCIRN provides a forum for cooperative planning among the principal North American and European research networking bodies. See also: Federal Networking Council, RARE. [Source: MALAMUD]

core gateway

Historically, one of a set of gateways (routers) operated by the Internet Network Operations Center at Bolt, Beranek and Newman (BBN). The core gateway system formed a central part of Internet routing in that all groups must advertise paths to their networks from a core gateway. [Source: MALAMUD]

Corporation for Research and Educational Networking (CREN)

This organization was formed in October 1989, when Bitnet and CSNET (Computer + Science NETwork) were combined under one administrative authority. CSNET is no longer operational, but CREN still runs Bitnet. See also: Bitnet. [Source: NNSC]

COS

Corporation for Open Systems. A vendor and user group for conformance testing, certification, and promotion of OSI products. [Source: RFC1208]

COSINE

Cooperation for Open Systems Interconnection Networking in Europe. A program sponsored by the European Commission, aimed at using OSI to tie together European research networks. [Source: RFC1208]

C-Pop

Core Point of Presence on JANET backbone.

cracker

A cracker is an individual who attempts to access computer systems without authorization. These individuals are often malicious, as opposed to hackers, and have many means at their disposal for breaking into a system. See also: hacker, Computer Emergency Response Team, Trojan Horse, virus, worm. [Source: RFC1392]

CRC

See: cyclic redundancy check

CREN

See: Corporation for Research and Educational Networking

CSMA/CD

Carrier Sense Multiple Access with Collision Detection. The access method used by local area networking technologies such as Ethernet. [Source: RFC1208]

CSNET

Computer+Science Network. Formerly a large computer network, mostly in the U.S. but with international connections. CSNET sites included universities, research labs, and some commercial companies. Now merged with BITNET to form CREN. See Corporation for Research and Educational Networking. [Source: RFC1208]

CU-SeeMe

Pronnounced "See you, See me," CU-SeeMe is a publicly available videoconferencing program developed at Cornell University. It allows anyone with audio/video capabilites and an Internet connection to videoconference with anyone else with the same capabilities. It also allows multiple people to tie into the same videoconference. [Source: RFC1983]

CWIS

See: Campus Wide Information system

Cyberspace

A term coined by William Gibson in his fantasy novel Neuromancer to describe the "world" of computers, and the society that gathers around them. [Source: ZEN]

Cyclic Redundancy Check (CRC)

A number derived from a set of data that will be transmitted. By recalculating the CRC at the remote end and comparing it to the value originally transmitted, the receiving node can detect some types of transmission errors. [Source: MALAMUD]

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DARPA

Defense Advanced Research Projects Agency. See: Advanced Research Projects Agency

Data Encryption Key (DEK)

Used for the encryption of message text and for the computation of message integrity checks (signatures). See also: encryption. [Source: RFC1392]

Data Encryption Standard (DES)

A popular, standard encryption scheme. See also: encryption, Pretty Good Privacy, RSA. [Source: RFC1983]

datagram

A self-contained, independent entity of data carrying sufficient information to be routed from the source to the destination computer without reliance on earlier exchanges between this source and destination computer and the transporting network. See also: frame, packet. [Source: J. Postel]

Data Link Layer

The OSI layer that is responsible for data transfer across a single physical connection, or series of bridged connections, between two Network entities. [Source: RFC1208]

DCA

See: Defense Information Systems Agency

DCE (1)

Data Circuit-terminating Equipment

DCE (2)

See: Distributed Computing Environment

DDN

See: Defense Data Network

DDN NIC

See: Defense Data Network Network Information Center

DECnet

A proprietary network protocol designed by Digital Equipment Corporation. The functionality of each Phase of the implementation, such as Phase IV and Phase V, is different. [Source: RFC1392]

default route

A routing table entry which is used to direct packets addressed to networks not explicitly listed in the routing table. [Source: MALAMUD]

Defense Advanced Research Projects Agency (DARPA)

See: Advanced Research Projects Agency.

Defense Data Network (DDN)

A global communications network serving the US Department of Defense composed of MILNET, other portions of the Internet, and classified networks which are not part of the Internet. The DDN is used to connect military installations and is managed by the Defense Information Systems Agency. See also: Defense Information Systems Agency. [Source: RFC1392]

Defense Data Network Network Information Center (DDN NIC)

Often called "The NIC", the DDN NIC's primary responsibility is the assignment of Internet network addresses and Autonomous System numbers, the administration of the root domain, and providing information and support services to the DDN. It is also a primary repository for RFCs. See also: Autonomous System, network address, Internet Registry, Network Information Center, Request For Comments. [Source: RFC1392]

Defense Information Systems Agency (DISA)

Formerly called the Defense Communications Agency (DCA), this is the government agency responsible for managing the DDN portion of the Internet, including the MILNET. Currently, DISA administers the DDN, and supports the user assistance services of the DDN NIC. See also: Defense Data Network. [Source: RFC1392]

DEK

See: Data Encryption Key

DES

See: Data Encryption Standard

DHCP

See: Dynamic Host Configuration Protocol

dialup

A temporary, as opposed to dedicated, connection between machines established over a standard phone line. [Source: RFC1392]

Directory Access Protocol

X.500 protocol used for communication between a Directory User Agent and a Directory System Agent. [Source: MALAMUD]

Directory System Agent (DSA)

The software that provides the X.500 Directory Service for a portion of the directory information base. Generally, each DSA is responsible for the directory information for a single organization or organizational unit. [Source: RFC1208]

Directory User Agent (DUA)

The software that accesses the X.500 Directory Service on behalf of the directory user. The directory user may be a person or another software element. [Source: RFC1208]

DISA

See: Defense Information Systems Agency

disassembling

Converting a binary program into human-readable machine language code. See also PAD.

Distributed Computing Environment (DCE)

An architecture of standard programming interfaces, conventions, and server functionalities (e.g., naming, distributed file system, remote procedure call) for distributing applications transparently across networks of heterogeneous computers. Promoted and controlled by the Open Software Foundation (OSF), a consortium led by Digital, IBM and Hewlett Packard. [Source: RFC1208]

distributed database

A collection of several different data repositories that looks like a single database to the user. A prime example in the Internet is the Domain Name System. [Source: RFC1392]

DIX Ethernet

See: Ethernet

DNS

See: Domain Name System

Document Type Definition

Definition of a language built on eXtensible Markup Language (XML) or Standardised General Markup Language (SGML).

domain

"Domain" is a heavily overused term in the Internet. It can be used in the Administrative Domain context, or the Domain Name context. See also: Administrative Domain, Domain Name System. [Source: RFC1392]

Domain Name System (DNS)

The DNS is a general purpose distributed, replicated, data query service. The principal use is the lookup of host IP addresses based on host names. The style of host names now used in the Internet is called "domain name", because they are the style of names used to look up anything in the DNS. Some important domains are: .COM (commercial), .EDU (educational), .NET (network operations), .GOV (U.S. government), and .MIL (U.S. military). Most countries also have a domain. The country domain names are based on ISO 3166. For example, .US (United States), .UK (United Kingdom), .AU (Australia). It is defined in STD 13, RFC 1034 and RFC 1035. See also: Fully Qualified Domain Name, Mail Exchange Record. [Source: RFC1983]

dot address (dotted decimal notation)

Dot address refers to the common notation for IP addresses of the form A.B.C.D; where each letter represents, in decimal, one byte of a four byte IP address. See also: IP address. [Source: FYI4]

DPA

Data Protection Act.

DS1

A framing specification for T-1 synchronous lines. See also: T1 [Source: RFC1392]

DS3

A framing specification for T-3 synchronous lines. See also: T3 [Source: RFC1392]

DSA

See: Directory System Agent

DSU

Data Service Unit, a physical cable interface on a network link.

DTD

See: Document Type Definition

DTE

Data Terminal Equipment

DUA

See: Directory User Agent

dynamic adaptive routing

Automatic rerouting of traffic based on a sensing and analysis of current actual network conditions. NOTE: this does not include cases of routing decisions taken on predefined information. [Source: J. Postel]

DUL

Dial-up User List, which has entries for ranges of IP addresses used by Internet Service Providers for modem users.

DWDM

Dense Wave Division Multiplexing, a technique for passing multiple data streams along an optical fibre cable using different wavelengths as carriers.

Dynamic Host Configuration Protocol (DHCP)

A framework for passing configuration information to hosts on a TCP/IP network, using an options field; a development from the BOOTP Bootstrap Protocol. Described in RFC 1533 and RFC 1534 and updated in RFC 2132. See also: BOOTP.

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E1

The basic building block for European multi-megabit data rates, with a bandwidth of 2.048Mbps. See also: T1. [Source: RFC1983]

E3

A European standard for transmitting data at 57.344Mbps. See also: T3. [Source: RFC1983]

EARN

European Academic and Research Network. See: Trans-European Research and Education Networking Association. [Source: RFC1983]

EaStMAN

Edinburgh and Stirling Metropolitan Area Network.

EastNet

East of England Regional Network.

EBCDIC

See: Extended Binary Coded Decimal Interchange Code

Ebone

A pan-European backbone service. [Source: RFC1392]

EFF

See: Electronic Frontier Foundation

EFLA

See: Extended Four Letter Acronym

EGP

See: Exterior Gateway Protocol

Electronic Frontier Foundation (EFF)

A foundation established to address social and legal issues arising from the impact on society of the increasingly pervasive use of computers as a means of communication and information distribution. [Source: RFC1392]

Electronic Mail (email)

A system whereby a computer user can exchange messages with other computer users (or groups of users) via a communications network. Electronic mail is one of the most popular uses of the Internet. [Source: NNSC]

email

See: Electronic mail

email address

The domain-based or UUCP address that is used to send electronic mail to a specified destination. For example an editor's address is "gmalkin@xylogics.com". See also: bang path, mail path, UNIX- to-UNIX CoPy. [Source: ZEN]

EMMAN

East Midlands Metropolitan Area Network.

encapsulation

The technique used by layered protocols in which a layer adds header information to the protocol data unit (PDU) from the layer above. As an example, in Internet terminology, a packet would contain a header from the physical layer, followed by a header from the datalink layer (e.g. Ethernet), followed by a header from the network layer (IP), followed by a header from the transport layer (TCP), followed by the application protocol data. [Source: RFC1208]

encryption

Encryption is the manipulation of a packet's data in order to prevent any but the intended recipient from reading that data. There are many types of data encryption, and they are the basis of network security. See also: Data Encryption Standard. [Source: RFC1392]

end system

An OSI system which contains application processes capable of communicating through all seven layers of OSI protocols. Equivalent to Internet host. [Source: RFC1208]

entity

OSI terminology for a layer protocol machine. An entity within a layer performs the functions of the layer within a single computer system, accessing the layer entity below and providing services to the layer entity above at local service access points. [Source: RFC1208]

error checking

The examination of received data for transmission errors. See also: checksum, Cyclic Redundancy Check. [Source: RFC1983]

ES-IS

End system to Intermediate system protocol. The OSI protocol by which end systems announce themselves to intermediate systems. [Source: RFC1208]

ESMTP

Extended Simple Mail Transfer Protocol. See Simple Mail Transfer Protocol.

Ethernet

A 10-Mb/s standard for LANs, initially developed by Xerox, and later refined by Digital, Intel and Xerox (DIX). All hosts are connected to a coaxial cable where they contend for network access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) paradigm. See also: 802.x, Local Area Network, token ring. [Source: RFC1392]

Ethernet meltdown

An 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. See also: broadcast storm. [Source: COMER]

ETSI

See: European Telecommunications Standards Institute

EUNet

European UNIX Network, an Internet Service Provider. [Source: RFC1208]

European Telecommunications Standards Institute

A pan-European organisation of administrations, network operators, manufacturers, service providers, research bodies and users. ETSI develops standards and tecnical documentation in telecommunications, broadcasting and information technology.

EUUG

European UNIX Users Group. [Source: RFC1208]

European Academic and Research Network (EARN)

European Academic and Research Network. See: Trans-European Research and Education Networking Association. [Source: RFC1983]

EWOS

European Workshop for Open Systems. The OSI Implementors Workshop for Europe. See OIW. [Source: RFC1208]

Extended Binary Coded Decimal Interchange Code (EBCDIC)

A standard character-to-number encoding used primarily by IBM computer systems. See also: ASCII. [Source: RFC1392]

Extendable Markup Language (XML)

A subset of Standardised General Markup Language, for development of markup applications using Document Type Definitions (DTDs) in areas such as database searches and information interchange, in electronic business transactions and eleswhere.

Extended Four Letter Acronym (EFLA)

A recognition of the fact that there are far too many TLAs. See also: Three Letter Acronym. [Source: K. Morgan]

Exterior Gateway Protocol (EGP)

A protocol which distributes routing information to the routers which connect autonomous systems. The term "gateway" is historical, as "router" is currently the preferred term. There is also a routing protocol called EGP defined in STD 18, RFC 904. See also: Autonomous System, Border Gateway Protocol, Interior Gateway Protocol. [Source: RFC1392]

eXternal Data Representation (XDR)

A standard for machine independent data structures developed by Sun Microsystems and defined in RFC 1014. It is similar to ASN.1. See also: Abstract Syntax Notation One. [Source: RFC1208]

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FARNET

A non-profit corporation, established in 1987, whose mission is to advance the use of computer networks to improve research and education. [Source: RFC1392]

FAQ

Frequently Asked Question [Source: RFC1392]

FaTMAN

Fife and Tayside Metropolitan Area Network.

Fawn Book

the document produced for the JNT defining the Simple Screen Management Protocol (SSMP).

FDDI

See: Fibre Distributed Data Interface

FEDA

Formerly Further Education Development Agency, now called Learning and Skills Development Agency (LSDA).

FEFC

Formerly Further Education Funding Council, now called Learning and Skills Council (LSC).

Federal Information Exchange (FIX)

One of the connection points between the American governmental internets and the Internet. [Source: SURA]

Federal Networking Council (FNC)

The coordinating group of representatives from those federal agencies involved in the development and use of federal networking, especially those networks using TCP/IP and the Internet. Current members include representatives from DOD, DOE, DARPA, NSF, NASA, and HHS. See also: Defense Advanced Research Projects Agency, National Science Foundation. [Source: RFC1392]

Fibre Distributed Data Interface (FDDI)

A high-speed (100Mb/s) LAN standard. The underlying medium is fibre optics, and the topology is a dual-attached, counter- rotating token ring. See also: Local Area Network, token ring. [Source: RFC1208]

file transfer

The copying of a file from one computer to another over a computer network. See also: File Transfer Protocol, Kermit, Gopher, World Wide Web. [Source: RFC1983]

File Transfer Protocol (FTP)

A protocol which allows a user on one host to access, and transfer files to and from, another host over a network. Also, FTP is usually the name of the program the user invokes to execute the protocol. The IP version is defined in STD 9, RFC 959. See also: anonymous FTP, FTAM. [Source: RFC1392]

Compare the Unix "Anonymous FTP" (see above) with the UK JNT Network Independent File Transfer Protocol or NIFTP (now almost extinct), also known as "Blue Book" (see above). The Unix commands are "ftp" and "hhcp" respectively.

finger

A protocol, defined in RFC 1288, that allows information about a system or user on a system to be retrived. Finger also refers to the commonly used program which retrieves this information. Information about all logged in users, as well is information about specific users may be retrieved from local or remote systems. Some sites consider finger to be a security risk and have either disabled it, or replaced it with a simple message. [Source: RFC1983]

FIPS

Federal Information Processing Standard.

FIX

See: Federal Information Exchange

flame

A strong opinion and/or criticism of something, usually as a frank inflammatory statement, in an electronic mail message. It is common to precede a flame with an indication of pending fire (i.e., FLAME ON!). Flame Wars occur when people start flaming other people for flaming when they shouldn't have. See also: Electronic Mail. [Source: RFC1392]

FLEA

See: Four Letter Extended Acronym

FNC

See: Federal Networking Council

For Your Information (FYI)

A subseries of RFCs that are not technical standards or descriptions of protocols. FYIs convey general information about topics related to TCP/IP or the Internet. See also: Request For Comments, STD. [Source: RFC1392]

FQDN

See: Fully Qualified Domain Name

fragment

A piece of a packet. When a router is forwarding an IP packet to a network that has a maximum packet size smaller than the packet size, it is forced to break up that packet into multiple fragments. These fragments will be reassembled by the IP layer at the destination host. See also: Maximum Transmission Unit. [Source: RFC1392]

fragmentation

The IP process in which a packet is broken into smaller pieces to fit the requirements of a physical network over which the packet must pass. See also: reassembly. [Source: RFC1392]

frame

A frame is a datalink layer "packet" which contains the header and trailer information required by the physical medium. That is, network layer packets are encapsulated to become frames. See also: datagram, encapsulation, packet. [Source: RFC1392]

freenet

Community-based bulletin board system with email, information services, interactive communications, and conferencing. Freenets are funded and operated by individuals and volunteers -- in one sense, like public television. They are part of the National Public Telecomputing Network (NPTN), an organization based in Cleveland, Ohio, devoted to making computer telecommunication and networking services as freely available as public libraries. [Source: LAQUEY]

FTAM

File Transfer, Access, and Management. The OSI remote file service and protocol. [Source: RFC1208]

FTP

See: File Transfer Protocol

Fully Qualified Domain Name (FQDN)

The FQDN is the full name of a system, rather than just its hostname. For example, "venera" is a hostname and "venera.isi.edu" is an FQDN. See also: hostname, Domain Name System. [Source: RFC1392]

FYI

See: For Your Information

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G.703

ITU-T standard for physical and logical traits of transmissions over digital circuits, including US 1.544Mbit/s and European 2.048Mbit/s (typically used to refer to the latter).

gated

Gatedaemon. A program which supports multiple routing protocols and protocol families. It may be used for routing, and makes an effective platform for routing protocol research. The software is freely available by anonymous FTP from "gated.cornell.edu". Pronounced "gate-dee". See also: Exterior Gateway Protocol, Open Shortest Path First..., Routing Information Protocol, routed. Source: RFC1983]

gateway

The term "router" is now used in place of the original definition of "gateway". Currently, a gateway is a communications device/program which passes data between networks having similar functions but dissimilar implementations. This should not be confused with a protocol converter. By this definition, a router is a layer 3 (network layer) gateway, and a mail gateway is a layer 7 (application layer) gateway. See also: mail gateway, router, protocol converter. [Source: RFC1392]

Gbit/s

Gigabits (thousand million - or strictly 2 to the power 30 - bits) per second.

GÉANT

A development from the former TEN-155 pan-European research network, creating a core network and access links to countries at Gigabit speeds.

General Packet Radio Service (GPRS)

An ETSI standard for packet-based wireless data communications at speeds up to a theoretical 171 kilobits per second, for continuous connection to the Internet, for portable computers and mobile phones. Addition of Virtual Private Network facilities will allow a degree of security for mobile access to important data. GPRS is based on the Global System for Mobile infrastructure, using up to 8 time slots (provided for 8 voice calls on a given frequency) only when there is information to transmit, rather than completely reserved as in a voice circuit. GPRS is being developed into Enhanced Data GSM Environment (EDGE), using a new modulation scheme for higher data rates up to 384 kilobits per second, as a step on the way to Universal Mobile Telecommunications Service (UMTS). See also: Virtual Private Network.

Global System for Mobile communications

An ETSI standard for second generation digital cellular wireless voice and data communications using time division multiple access transmission methods. Formerly known as Groupe Spécial Mobile, which was the study group of the Conference of European Posts and Telegraphs (CEPT) set up to develop a pan-European system for terrestrial mobiles.

Gopher

A distributed information service developed at the University of Minnesota, that makes available hierarchical collections of information across the Internet. Gopher uses a simple protocol, defined in RFC 1436, that allows a single Gopher client to access information from any accessible Gopher server, providing the user with a single "Gopher space" of information. Public domain versions of the client and server are available. See also: archie, archive site, Prospero, Wide Area Information Servers. [Source: RFC1392]

GOSIP

See: Government OSI Profile

Government OSI Profile

A subset of OSI standards specific to U.S. Government procurements, designed to maximize interoperability in areas where plain OSI standards are ambiguous or allow excessive options. [Source: BIG-LAN]

GPRS

See: General Packet Radio Service

Green Book

the document listing recommendations on the use of Triple-X and the definition of the TS29 protocol, formerly used in UK Universities.

Grey Book

the document describing the JNT Interim Mail Protocol used in the UK for mail transfers. Mostly superseded by Internet mail protocols such as SMTP (q.v.).

gross

A dozen dozen (144).

GSM

See: Global System for Mobile communications

GUI

Graphical User Interface, typically consisting of windows, menus and pointer (e.g. mouse) hence WIMP.

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hacker

A person who delights in having an intimate understanding of the internal workings of a system, computers and computer networks in particular. The term is often misused in a pejorative context, where "cracker" would be the correct term. See also: cracker. [Source: RFC1392]

HDLC

High level Data Link Control, ISO standard for carrying data over a link with error and flow control.

header

The portion of a packet, preceding the actual data, containing source and destination addresses, and error checking and other fields. A header is also the part of an electronic mail message that precedes the body of a message and contains, among other things, the message originator, date and time. See also: Electronic Mail, packet, error checking. [Source: RFC1392]

heterogeneous network

A network running multiple network layer protocols. See also: DECnet, IP, IPX, XNS, homogeneous network. [Source: RFC1983]

hierarchical routing

The complex problem of routing on large networks can be simplified by reducing the size of the networks. This is accomplished by breaking a network into a hierarchy of networks, where each level is responsible for its own routing. The Internet has, basically, three levels: the backbones, the mid-levels, and the stub networks. The backbones know how to route between the mid-levels, the mid-levels know how to route between the sites, and each site (being an autonomous system) knows how to route internally. See also: Autonomous System, Exterior Gateway Protocol, Interior Gateway Protocol, stub network, transit network. [Source: RFC1392]

High Performance Computing and Communications (HPCC)

High performance computing encompasses advanced computing, communications, and information technologies, including scientific workstations, supercomputer systems, high speed networks, special purpose and experimental systems, the new generation of large scale parallel systems, and application and systems software with all components well integrated and linked over a high speed network. [Source: HPCC]

High Performance Parallel Interface (HIPPI)

An emerging ANSI standard which extends the computer bus over fairly short distances at speeds of 800 and 1600 Mb/s. HIPPI is often used in a computer room to connect a supercomputer to routers, frame buffers, mass-storage peripherals, and other computers. See also: American National Standards Institute [Source: MALAMUD]

HIPERLAN

High Performance radio Local Area Network, an ESTI standard EN 300 652 for high speed data communications at 20Mbit/s in the 5GHz range, either between portable devices or as an extension of a wired network infrastructure. There is a development to produce HIPERLAN2, which can be used for 3G mobile phone core networks as well as 54Mbit/s data networks in the 5GHz radio range. See also 802.11, Wireless Local Area Network.

HIPPI

See: High Performance Parallel Interface

homogeneous network

A network running a single network layer protocol. See also: DECnet, IP, IPX, XNS, heterogeneous network. [Source: RFC1983]

hop

A term used in routing. A path to a destination on a network is a series of hops, through routers, away from the origin. [Source: RFC1392]

host

A computer that allows users to communicate with other host computers on a network. Individual users communicate by using application programs, such as electronic mail, Telnet and FTP. [Source: NNSC]

host address

See: internet address

hostname

The name given to a machine. See also: Fully Qualified Domain Name. [Source: ZEN]

host number

See: host address

HPCC

See: High Performance Computing and Communications

HTML

See: Hypertext Markup Language

HTTP

See: Hypertext Transfer Protocol

hub

A device connected to several other devices. In ARCnet, a hub is used to connect several computers together. In a message handling service, a hub is used for the transfer of messages across the network. [Source: MALAMUD]

hyperlink

A pointer within a hypertext document which points (links) to another document, which may or may not also be a hypertext document. See also: hypertext. [Source: RFC1983]

hypertext

A document, written in HTML, which contains hyperlinks to other documents, which may or may not also be hypertext documents. Hypertext documents are usually retrieved using WWW. See also: hyperlink, Hypertext Markup Language, World Wide Web. [Source: RFC1983]

Hypertext Markup Language (HTML)

The language used to create hypertext documents. It is a subset of SGML and includes the mechanisms to establish hyperlinks to other documents. See also: hypertext, hyperlink, Standardized General Markup Language. [Source: RFC1983]

Hypertext Markup Protocol (HTTP)

The protocol used by WWW to transfer HTML files. A formal standard is still under development in the IETF. See also: hyperlink, hypertext, Hypertext Markup Language, World Wide Web. [Source: RFC1983]

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I-D

See: Internet-Draft

IAB

See: Internet Architecture Board

IANA

See: Internet Assigned Numbers Authority

ICANN

See: Internet Corporation for Assigned Numbers and Names

ICMP

See: Internet Control Message Protocol

ICT

Information and Communications Technologies (or variations thereof, sometimes CIT).

IEAK

Internet Explorer Administration Kit (Microsoft).

IEEE

Institute of Electrical and Electronics Engineers

IEEE 802

See: 802.x

IEN

See: Internet Experiment Note

IESG

See: Internet Engineering Steering Group

IETF

See: Internet Engineering Task Force

IINREN

See: Interagency Interim National Research and Education Network

IIS

Internet Information Service (Microsoft).

IGP

See: Interior Gateway Protocol

IGRP

Internet Gateway Routing Protocol. A proprietary IGP used by cisco System's routers. [Source: RFC1208]

IMAP

See: Internet Message Access Protocol

IMHO

"In My Humble Opinion"; usually accompanies a statement that may bring about personal offense or strong disagreement. Rarely used in Yorkshire, where opinions are anything but humble, especially about cricket or rugby.

IMR

See: Internet Monthly Report

INTAP

Interoperability Technology Association for Information Processing. The technical organization which has the official charter to develop Japanese OSI profiles and conformance tests. [Source: RFC1208]

Integrated Services Digital Network (ISDN)

An emerging technology which is beginning to be offered by the telephone carriers of the world. ISDN combines voice and digital network services in a single medium, making it possible to offer customers digital data services as well as voice connections through a single "wire". The standards that define ISDN are specified by CCITT. See also: CCITT. [Source: RFC1208]

Interagency Interim National Research and Education Network (IINREN)

An evolving operating network system. Near term (1992-1996) research and development activities will provide for the smooth evolution of this networking infrastructure into the future gigabit NREN. [Source: HPCC]

Interior Gateway Protocol (IGP)

A protocol which distributes routing information to the routers within an autonomous system. The term "gateway" is historical, as "router" is currently the preferred term. See also: Autonomous System, Exterior Gateway Protocol, Open Shortest Path First..., Routing Information Protocol. [Source: RFC1392]

Intermediate System (IS)

An OSI system which performs network layer forwarding, i.e. not an end system. It is analogous to an IP router. See also: Open Systems Interconnection, router. [Source: RFC1392]

Intermediate System-Intermediate System (IS-IS)

The OSI IGP. See also: Open Systems Interconnection, Interior Gateway Protocol. [Source: RFC1392]

International Organization for Standardization (ISO)

A voluntary, nontreaty organization founded in 1946 which is responsible for creating international standards in many areas, including computers and communications. Its members are the national standards organizations of the 89 member countries, including ANSI for the U.S. See also: American National Standards Institute, Open Systems Interconnection. [Source: TAN]

International Telecommunications Union (ITU)

An agency of the United Nations which coordinates the various national telecommunications standards so that people in one country can communicate with people in another country. [Source: RFC1983]

International Telecommunications Union - Telecommunications (ITU-T)

The new name for CCITT since the ITU reorganization. The function is the same; only the name has been changed. [Source: RFC1983]

internet

While an internet is a network, the term "internet" is usually used to refer to a collection of networks interconnected with routers. See also: network. [Source: RFC1392]

Internet

(note the capital "I") The Internet is the largest internet in the world. Is a three level hierarchy composed of backbone networks (e.g., Ultranet), mid-level networks (e.g., NEARnet) and stub networks. The Internet is a multiprotocol internet. See also: backbone, mid-level network, stub network, transit network, Internet Protocol. [Source: RFC1983]

internet address

A IP address that uniquely identifies a node on an internet. An Internet address (capital "I"), uniquely identifies a node on the Internet. See also: internet, Internet, IP address. [Source: RFC1392]

Internet Architecture Board (IAB)

The IAB has been many things over the years. Originally the Internet Activities Board, it was responsible for the development of the protocols which make up the Internet. It later changed its name and charter to become the group most responsible for the architecture of the Internet, leaving the protocol details to the IESG. In June of 1992, it was chartered as a component of the Internet Society; this is the charter it holds today. The IAB is responsible for approving nominations to the IESG, architectural oversight for Internet Standard Protocols, IETF standards process oversight and appeals, IANA and RFC activities, and liaison to peer standards groups (e.g., ISO). See also: Internet Engineering Task Force, Internet Research Task Force, Internet Engineering Steering Group, Internet Assigned Numbers Authority, Request for Comments. [Source: RFC1983]

Internet Assigned Numbers Authority (IANA)

The central registry for various Internet protocol parameters, such as port, protocol and enterprise numbers, and options, codes and types. The currently assigned values are listed in the "Assigned Numbers" document [STD2]. To request a number assignment, contact the IANA at "iana@isi.edu". Now superseded by ICANN. See also: assigned numbers, STD. [Source: RFC1983]

Internet Corporation for Assigned Numbers and Names (ICANN)

Successor to Internet Assigned Numbers Authority for Internet management functions performed under contract to US Government.

Internet Control Message Protocol (ICMP)

ICMP is an extension to the Internet Protocol. It allows for the generation of error messages, test packets and informational messages related to IP. It is defined in STD 5, RFC 792. [Source: FYI4]

Internet-Draft (I-D)

Internet-Drafts are working documents of the IETF, its Areas, and its Working Groups. As the name implies, Internet-Drafts are draft documents. They are valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. Very often, I-Ds are precursors to RFCs. See also: Internet Engineering Task Force, Request For Comments. [Source: RFC1392]

Internet Engineering Planning Group (IEPG)

A group, primarily composed of Internet service operators, whose goal is to promote a globally coordinated Internet operating environment. Membership is open to all. [Source: RFC1983]

Internet Engineering Steering Group (IESG)

The IESG is composed of the IETF Area Directors and the IETF Chair. It provides the first technical review of Internet standards and is responsible for day-to-day "management" of the IETF. See also: Internet Engineering Task Force. [Source: RFC1392]

Internet Engineering Task Force (IETF)

The IETF is a large, open community of network designers, operators, vendors, and researchers whose purpose is to coordinate the operation, management and evolution of the Internet, and to resolve short-range and mid-range protocol and architectural issues. It is a major source of proposals for protocol standards which are submitted to the IAB for final approval. The IETF meets three times a year and extensive minutes are included in the IETF Proceedings. See also: Internet, Internet Architecture Board. [Source: FYI4]

Internet Experiment Note (IEN)

A series of reports pertinent to the Internet. IENs were published in parallel to RFCs and were intended to be "working documents." They have been replaced by Internet-Drafts and are currently of historic value only. See also: Internet-Draft, Request For Comments. [Source: RFC1392]

Internet Message Access Protocol (IMAP)

A protocol defined by RFC2060 and others, allowing a client to read and manipulate electronic mail messages and message folders (mailboxes) on a server.

Internet Monthly Report (IMR)

Published monthly, the purpose of the Internet Monthly Reports is to communicate to the Internet Research Group the accomplishments, milestones reached, or problems discovered by the participating organizations. [Source: RFC1392]

internet number

See: internet address

Internet Protocol (IP, IPv4)

The Internet Protocol (version 4), defined in RFC 791, is the network layer for the TCP/IP Protocol Suite. It is a connectionless, best-effort packet switching protocol. See also: packet switching, TCP/IP Protocol Suite, Internet Protocol Version 6. [Source: RFC1983]

Internet Protocol security (IPsec)

A packet layer security standard consisting of Authentication Header (AH) and Encapsulating Security Payload (ESP) elements, defined in RFC 2402 and RFC 2406 respectively. Useful for Virtual Private Networks.

Internet Protocol Version 6 (IPng, IPv6)

IPv6 (version 5 is a stream protocol used for special applications) is a new version of the Internet Protocol which is designed to be an evolutionary step from its predecessor, version 4. There are many RFCs defining various portions of the protocol, its auxiliary protocols, and the transition plan from IPv4. The core RFCs are 1883, 1884, 1885 and 1886; also updated at RFC2460. The name IPng (IP next generation) is a nod to STNG (Star Trek Next Generation). [Source: RFC1392]

Internet Registry (IR)

The IANA has the discretionary authority to delegate portions of its responsibility and, with respect to network address and Autonomous System identifiers, has lodged this responsibility with an IR. The IR function is performed by the DDN NIC. See also: Autonomous System, network address, Defense Data Network..., Internet Assigned Numbers Authority. [Source: RFC1392]

Internet Relay Chat (IRC)

A 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. See also: talk. [Source: HACKER]

Internet Research Steering Group (IRSG)

The "governing body" of the IRTF. See also: Internet Research Task Force. [Source: MALAMUD]

Internet Research Task Force (IRTF)

The IRTF is chartered by the IAB to consider long-term Internet issues from a theoretical point of view. It has Research Groups, similar to IETF Working Groups, which are each tasked to discuss different research topics. Multi-cast audio/video conferencing and privacy enhanced mail are samples of IRTF output. See also: Internet Architecture Board, Internet Engineering Task Force, Privacy Enhanced Mail. [Source: RFC1392]

Internet Society (ISOC)

The Internet Society is a non-profit, professional membership organization which facilitates and supports the technical evolution of the Internet, stimulates interest in and educates the scientific and academic communities, industry and the public about the technology, uses and applications of the Internet, and promotes the development of new applications for the system. The Society provides a forum for discussion and collaboration in the operation and use of the global Internet infrastructure. The Internet Society publishes a quarterly newsletter, the Internet Society News, and holds an annual conference, INET. The development of Internet technical standards takes place under the auspices of the Internet Society with substantial support from the Corporation for National Research Initiatives under a cooperative agreement with the US Federal Government. [Source: V. Cerf]

Internetwork Packet eXchange (IPX)

Novell's protocol used by Netware. A router with IPX routing can interconnect LANs so that Novell Netware clients and servers can communicate. See also: Local Area Network. [Source: RFC1392]

InterNIC

A five year project, partially supported by the National Science Foundation, to provide network information services to the networking community. The InterNIC began operations in April of 1993 and is now a collaborative project of two organizations: AT&T, which provides Directory and Database Services from South Plainsfield, NJ; and Network Solutions, Inc., which provides Registration Services from their headquarters in Herndon, VA. Services are provided via the Internet, and by telephone, FAX, and hardcopy. [Source: RFC1983]

interoperability

The ability of software and hardware on multiple machines from multiple vendors to communicate meaningfully. [Source: RFC1392]

IONL

Internal Organization of the Network Layer. The OSI standard for the detailed architecture of the Network Layer. Basically, it partitions the Network layer into subnetworks interconnected by convergence protocols (equivalent to internetworking protocols), creating what Internet calls a catenet or internet. [Source: RFC1208]

IP (IPv4)

See: Internet Protocol

IP address

The 32-bit address defined by the Internet Protocol in RFC 791. It is usually represented in dotted decimal notation. See also: dot address, internet address, Internet Protocol, network address, subnet address, host address. [Source: RFC1392]

IP datagram

See: datagram

IPng (IPv6)

See: Internet Protocol Version 6

IPsec

See: Internet Protocol security

IPX

See: Internetwork Packet eXchange

IR

See: Internet Registry

IRC

See: Internet Relay Chat

IRSG

See: Internet Research Steering Group

IRTF

See: Internet Research Task Force

IS

See: Intermediate System

IS-IS

See: Intermediate System-Intermediate System

ISDN

See: Integrated Services Digital Network

ISO

See: International Organization for Standardization

ISO Development Environment (ISODE)

Software that allows OSI services to use a TCP/IP network. Pronounced eye-so-dee-eee. See also: Open Systems Interconnection, TCP/IP Protocol Suite. [Source: RFC1392]

ISOC

See: Internet Society

ISODE

See: ISO Development Environment

ISP

Internet Service Provider, a purveyor of access to the Internet.

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JANET

Formerly Joint Academic Network. The United Kingdom education and research network. See also SUPERJANET.

JANET-CERT

JANET Computer Emergency Response Team. See also: Computer Emergency Response Team.

JANET National User Group (JNUG)

The JANET National User Group (JNUG) represents the views and concerns of people who use the national academic network, JANET, to those who are responsible for its funding. The Group encompasses representatives from Regional User Groups and Affiliated Groups.

JANET User Group for Administration (JUGA)

The JANET User Group for Administration (JUGA) exists to promote the use of information technology, primarily via JANET by administrators in Higher Education. JUGA is a Affiliated Group of the JANET National User Group, through which the views of the users on JANET and UKERNA services are presented to the JISC Committee on Networking. See also: JANET National User Group.

JANET User Group for Libraries (JUGL)

The JANET User Group for Libraries (JUGL) supports Library and Information Professionals in the use and development of Electronic Networking for information provision. JUGL is a Affiliated Group of the JANET National User Group, through which the views of the users on JANET and UKERNA services are presented to the JISC Committee on Networking. See also: JANET National User Group.

JANET Yorkshire and Northumbria Regional User Group (JYNRUG)

The JANET Yorkshire and Northumbria Regional User Group represents the views of users of JANET within the ancient regions of Yorkshire and Northumbria, plus any modern additions. See also: JANET National User Group.

JCALT

JISC Committee for Awareness, Liaison and Training, promoting use and effectiveness of ICT in post-16 education.

JCCS

JISC Committee for Content and Services, to identify, procure and deliver content for all sectors of further and higher education, within a content management structure, for maximum uptake of resources.

JCLT

JISC Committee for Learning and Teaching, to facilitate coordination and effectiveness of Information Learning Technologies (ILT) in learning and teaching in UK colleges and universities.

JCIE

JISC Committee for Information Environment, build on existing strategies, to create a common information environment, with mechanisms for access and delivery of resources and finding quality information of relevance.

JCN

JISC Committee for Networking, which oversees JISC-funded networking and networked services, including JANET.

JCP

JANET Connection Point.

JCS

JANET Customer Service, at UKERNA.

JCSR

JISC Committee for Support of Research, to identify requirements of the research community which can be met from the JISC budget, and work with the Research Grid community e.g. on e-science programmes.

JCUR

JANET Connection and Upgrade Form, from UKERNA.

JIPS

The JANET Internet Protocol Service (JIPS) was the IP service on JANET, in its X.25 network days, using the technique of "IP tunnelling" - ie encapsulation of the X.25 packets into TCP/IP packets. The result was that UK institutions could connect to hosts on the world wide Internet with programs such as telnet, anonymous ftp, gopher and World Wide Web browsers, before JANET became a fully IP network.

JISC

Joint Information Systems Committee, consisting of representatives of UK Funding Councils and other stakeholders, for controlling budgets on networking and other information systems projects. There are six subcommittees as constituted in February 2002, JCALT, JCCS, JCLT, JCIE, JCN and JCSR.

JISC Assist

JISC Activities, Services and Special Initiatives Support Team, which is the awareness-raising unit for better understanding of the role of information systemsa and information technology in further and higher education institutions.

JISCMail

The National Academic Mailing List Service, based at the Rutherford Appleton Laboratory.

JISC Technology Applications Programme

iA programme of over 100 projects to develop and demonstrate applications of Information and Communication Technology, produce technology reviews and establish four clearing houses to promote use of ICT to support staff and students in HIgher Education.

JKREY

Joyce K. Reynolds

JNT

the former UK Joint Network Team; sponsored by the Computer Board and SERC to manage academic network developments. Now known as UKERNA.

JNUG

See: JANET National User Group

JOD

JANET Operations Desk, based in London.

JTAP

See: JISC Technology Allicationa Programme

JTMP

Job Transfer and Manipulation Protocol; a protocol designed to allow jobs to be sent from one computer to another to be executed, and to allow specifications of output handling. See also Red Book.

JUGA

See: JANET User Group for Administration

JUGL

See: JANET User Group for Libraries

JUNET

Japan UNIX Network. [Source: RFC1208]

JWCS

JANET Web Cache Service, also known as the National Cache.

JYNRUG

See: JANET Yorkshire and Northumbria Regional User Group

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KA9Q

A popular implementation of TCP/IP and associated protocols for amateur packet radio systems. See also: TCP/IP Protocol Suite. [Source: RFC1208]

kbit/s

Kilobits (thousand - or strictly 2 to the power 10 - bits) per second.

Kentish MAN

Metropolitan Area Network for Kent (there is no MAN of Kent).

Kerberos

Kerberos is the security system of MIT's Project Athena. It is based on symmetric key cryptography. See also: encryption. [Source: RFC1392]

Kermit

A popular file transfer protocol developed by Columbia University. Because Kermit runs in most operating environments, it provides an easy method of file transfer. Kermit is NOT the same as FTP. See also: File Transfer Protocol [Source: MALAMUD]

kernel

The level of an operating system or networking system that contains the system-level commands or all of the functions hidden from the user. In a Unix system, the kernel is a program that contains the device drivers, the memory management routines, the scheduler, and system calls. This program is always running while the system is operating.

Knowbot

A "Knowledge Robot" is a program which seeks out information based on specified criteria. "Knowbot," as trademarked by CNRI, refers specifically to the search engine for Knowbot Information Services. See also: Corporation for National Research Initiatives, X.500, white pages, whois, netfind. [Source: RFC1983]

Knowbot Information Services

An experimental directory service. See also: white pages, WHOIS, X.500. [Source: RFC1983]

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LAN

See: Local Area Network

layer

Communication networks for computers may be organized as a set of more or less independent protocols, each in a different layer (also called level). The lowest layer governs direct host-to-host communication between the hardware at different hosts; the highest consists of user applications. Each layer builds on the layer beneath it. For each layer, programs at different hosts use protocols appropriate to the layer to communicate with each other. TCP/IP has five layers of protocols; OSI has seven. The advantages of different layers of protocols is that the methods of passing information from one layer to another are specified clearly as part of the protocol suite, and changes within a protocol layer are prevented from affecting the other layers. This greatly simplifies the task of designing and maintaining communication programs. See also: Open Systems Interconnection, TCP/IP Protocol Suite. [Source: RFC1392]

LDAP

See: Lightweight Directory Access Protocol.

learndirect

The learning services for Ufi are delivered through learndirect, which provides information and advice on high quality courses.

LeNSE

Learning Network for the South East.

Lightweight Directory Access Protocol

This protocol provides access for management and browser applications that provide read/write interactive access to the X.500 Directory. See also: X.500. [Source: RFC1983]

link

A pointer which may be used to retreive the file or data to which the pointer points. [Source: RFC1983]

LINX

London InterNet eXchange, an interconnection point for Internet Service providers in the UK (and elsewhere).

list server

An automated mailing list distribution system. List servers handle the administrivia of mailing list maintenance, such as the adding and deleting of list members. See also: mailing list. [Source: RFC1983]

listserv

An automated mailing list distribution system originally designed for the Bitnet/EARN network. See also: mailing list. [Source: RFC1392]

little-endian

A format for storage or transmission of binary data in which the least significant byte (bit) comes first. See also: big-endian. [Source: RFC1208]

LJUG

See: London JANET User Group

LLC

See: Logical Link Control

LMN

London Metropolitan Network.

Local Area Network (LAN)

A data network intended to serve an area of only a few square kilometers or less. Because the network is known to cover only a small area, optimizations can be made in the network signal protocols that permit data rates up to 100Mb/s. See also: Ethernet, Fibre Distributed Data Interface, token ring, Metropolitan Area Network, Wide Area Network, Wireless Local Area Network. [Source: NNSC]

Logical Link Control (LLC)

The upper portion of the datalink layer, as defined in IEEE 802.2. The LLC sublayer presents a uniform interface to the user of the datalink service, usually the network layer. Beneath the LLC sublayer is the MAC sublayer. See also: 802.x, layer, Media Access Control. [Source: RFC1392]

London JANET User Group (LJUG)

The London JANET User Group presents the views of the users on JANET and UKERNA services to the JISC Committee on Networking through the JANET National User Group. See also: JANET National User Group.

LSC

Learning and Skills Council, successor to FEFC.

LSDA

Learning and Skills Development Agency, successor to FEDA.

Lurking

No active participation on the part of a subscriber to an mailing list or USENET newsgroup. A person who is lurking is just listening to the discussion. Lurking is encouraged for beginners who need to get up to speed on the history of the group. See also: Electronic Mail, mailing list, Usenet. [Source: LAQUEY]

Lycos

Lycos, Inc. is a new venture formed in late June 1995, to develop and market the Lycos technology originally developed under the direction of Dr. Michael ("Fuzzy") Mauldin at Carnegie Mellon University. The part of Lycos you see when you do a search is the search engine. "Lycos" comes from Lycosidae, a cosmopolitan family of relatively large active ground spiders (Wolf Spiders) that catch their prey by pursuit, rather than in a web. [Source: Lycos's FAQ]

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MAC

See: Media Access Control

MAC address

The hardware address of a device connected to a shared media. See also: Media Access Control, Ethernet, token ring. [Source: MALAMUD]

mail bridge

A mail gateway that forwards electronic mail between two or more networks while ensuring that the messages it forwards meet certain administrative criteria. A mail bridge is simply a specialized form of mail gateway that enforces an administrative policy with regard to what mail it forwards. See also: Electronic Mail, mail gateway. [Source: NNSC]

Mail Exchange Record (MX Record)

A DNS resource record type indicating which host can handle mail for a particular domain. See also: Domain Name System, Electronic Mail. [Source: MALAMUD]

mail exploder

Part of an electronic mail delivery system which allows a message to be delivered to a list of addresses. Mail exploders are used to implement mailing lists. Users send messages to a single address and the mail exploder takes care of delivery to the individual mailboxes in the list. See also: Electronic Mail, email address, mailing list. [Source: RFC1208]

mail gateway

A machine that connects two or more electronic mail systems (including dissimilar mail systems) and transfers messages between them. Sometimes the mapping and translation can be quite complex, and it generally requires a store-and-forward scheme whereby the message is received from one system completely before it is transmitted to the next system, after suitable translations. See also: Electronic Mail. [Source: RFC1208]

mail path

A series of machine names used to direct electronic mail from one user to another. This system of email addressing has been used primarily in UUCP networks which are trying to eliminate its use altogether. See also: bang path, email address, UNIX-to-UNIX CoPy. [Source: RFC1392]

mail server

A software program that distributes files or information in response to requests sent via email. Internet examples include Almanac and netlib. Mail servers have also been used in Bitnet to provide FTP-like services. See also: Bitnet, Electronic Mail, FTP. [Source: NWNET]

mailing list

A list of email addresses, used by a mail exploder, to forward messages to groups of people. Generally, a mailing list is used to discuss certain set of topics, and different mailing lists discuss different topics. A mailing list may be moderated. This means that messages sent to the list are actually sent to a moderator who determines whether or not to send the messages on to everyone else. Requests to subscribe to, or leave, a mailing list should ALWAYS be sent to the list's "-request" address (e.g., ietf-request@cnri.reston.va.us for the IETF mailing list) or majordomo server. See also: Electronic Mail, mail exploder, email address, moderator, majordomo. [Source: RFC1983]

majordomo

A program which handles mailing list maintenance (affectionately known as administrivia) such as adding and removing addresses from mailing lists. See also: email address, mailing list. [Source: RFC1983]

MAN

See: Metropolitan Area Network

Management Information Base (MIB)

The set of parameters an SNMP management station can query or set in the SNMP agent of a network device (e.g., router). Standard, minimal MIBs have been defined, and vendors often have Private enterprise MIBs. In theory, any SNMP manager can talk to any SNMP agent with a properly defined MIB. See also: client-server model, Simple Network Management Protocol, SMI. [Source: BIG-LAN]

MAPS

Mail Abuse Prevention System.

Martian

A humorous term applied to packets that turn up unexpectedly on the wrong network because of bogus routing entries. Also used as a name for a packet which has an altogether bogus (non-registered or ill-formed) internet address. [Source: RFC1208]

MAU (1)

Multistation Access Unit, for connection and control of Token Ring network stations in a star arrangement. Also known as MSAU.

MAU (2)

Monitoring and Advisory Unit, a JISC-sponsored service to manage contracts between JISC and several JISC-funded services.

Maximum Transmission Unit (MTU)

The largest frame length which may be sent on a physical medium. See also: frame, fragmentation, frame. [Source: RFC1392]

Mbit/s

Megabits (million - or strictly 2 to the power 20 - bits) per second.

mbone

The Multicast Backbone is based on IP multicasting using class-D addresses. The mbone concept was adopted at the March 1992 IETF in San Diego, during which it was used to audiocast to 40 people throughout the world. At the following meeting, in Cambridge, the name mbone was adopted. Since then the audiocast has become full two-way audio/video conferencing using two video channels, four audio channels, and involving hundreds of remote users. See also: multicast, Internet Engineering Task Force. [Source: RFC1983]

MD-2, MD-4, MD-5

See: Message Digest.

Media Access Control (MAC)

The lower portion of the datalink layer. The MAC differs for various physical media. See also: MAC Address, Ethernet, Logical Link Control, token ring. [Source: RFC1392]

medium

The material used to support the transmission of data. This can be copper wire, coaxial cable, optical fibre, or electromagnetic wave (as in microwave).

Message Digest (MD-2, MD-4, MD-5)

Message digests are algorithmic operations, generally performed on text, which produce a unique signature for that text. MD-2, described in RFC 1319; MD-4, described in RFC 1320; and MD-5, described in RFC 1321 all produce a 128-bit signature. They differ in their operating speed and resistance to crypto-analytic attack. Generally, one must be traded off for the other. [Source: RFC1983]

message switching

See: packet switching

Metropolitan Area Network (MAN)

A data network intended to serve an area approximating that of a large city. Such networks are being implemented by innovative techniques, such as running fibre cables through subway tunnels. A popular example of a MAN is SMDS. See also: Local Area Network, Switched Multimegabit Data Service, Wide Area Network. [Source: NNSC]

MHS

Message Handling System. The system of message user agents, message transfer agents, message stores, and access units which together provide OSI electronic mail. MHS is specified in the CCITT X.400 series of Recommendations. [Source: RFC1208]

MIB

See: Management Information Base

Microcom Networking Protocol (MNP)

A series of protocols built into most modems which error-check or compress data being transmitted over a phone line. [Source: RFC1983]

MidJUG

See: Midlands JANET User Group

Midlands JANET User Group (MidJUG)

The Midlands JANET User Group presents the views of the users on JANET and UKERNA services to the JISC Committee on Networking through the JANET National User Group. See also: JANET National User Group.

mid-level network

Mid-level networks (a.k.a. regionals) make up the second level of the Internet hierarchy. They are the transit networks which connect the stub networks to the backbone networks. See also: backbone, Internet, stub network, transit network. [Source: RFC1392]

MidMAN

Midlands Metropolitan Area Network.

MILNET

MILitary NETwork. Originally part of the ARPANET, MILNET was partitioned in 1984 to make it possible for military installations to have reliable network service, while the ARPANET continued to be used for research. See DDN. [Source: RFC1208]

MIME

See: Multipurpose Internet Mail Extensions

MMC

Microsoft Management Console.

MNP

See: Microcom Networking Protocol.

moderator

A person, or small group of people, who manage moderated mailing lists and newsgroups. Moderators are responsible for determining which email submissions are passed on to list. See also: Electronic Mail, mailing list, Usenet. [Source: RFC1392]

MOSPF

Multicast Open Shortest-Path First. See: Open Shortest-Path First. [Source: RFC1983]

MSC

Monitoring SubCommittee, a subcommittee of JCN to monitor the performance of JANET, now superseded by SPAG.

MTA

Message Transfer Agent. An OSI application process used to store and forward messages in the X.400 Message Handling System. Equivalent to Internet mail agent. [Source: RFC1208]

MTU

See: Maximum Transmission Unit

MUD

See: Multi-User Dungeon

multicast

A packet with a special destination address which multiple nodes on the network may be willing to receive. See also: broadcast, unicast. [Source: RFC1208]

multihomed host

A host which has more than one connection to a network. The host may send and receive data over any of the links but will not route traffic for other nodes. See also: host, router. [Source: MALAMUD]

multiplex

The division of a single transmission medium into multiple logical channels supporting many simultaneous sessions. For example, one network may have simultaneous FTP, telnet, rlogin, and SMTP connections, all going at the same time.

Multipurpose Internet Mail Extensions (MIME)

An extension to Internet email which provides the ability to transfer non-textual data, such as graphics, audio and fax. It is defined in RFC 1341. See also: Electronic Mail. [Source: RFC1392]

Multi-User Dungeon (MUD)

Adventure, role playing games, or simulations played on the Internet. Devotees call them "text-based virtual reality adventures". The games can feature fantasy combat, booby traps and magic. Players interact in real time and can change the "world" in the game as they play it. Most MUDs are based on the Telnet protocol. See also: Teln