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Internet and Internet Exchange Definitions, Acronyms and Abbreviations

Name Description
100BaseT A cabling and interface specification for data transmission at 100Mbps using twisted pair copper cable. See also: Cat5.
24x7 Also, 24x365 (and somewhat incorrectly 24x7x365). Shorthand to describe a service with availability 24 hours a day, every day. Often used in reference to support desks, help lines etc.
Acceptable Use Policy. A policy drawn up by an ISP detailing what is deemed to be acceptable use of their service by their customers.
Address Resolution Protocol (ARP) A protocol for mapping an IP address to a physical machine address that is recognised on a LAN.
Advanced Research Projects Agency Network (ARPANET) The forerunner of today's Internet. Funded mainly by U.S. military sources, it consisted of a number of computers connected by leased lines and used a packet switched technology.
Africa Network Information Centre (AFRINIC) An emerging RIR responsible for Africa, which is currently covered by RIPE (North of the Equator) and ARIN (South of the Equator).
AFRINIC Africa Network Information Centre.
American Registry for Internet Numbers (ARIN) The RIR responsible for the Americas, The Caribbean and Africa south of the Equator. See also: RIPE NCC, APNIC.
APNIC Asia Pacific Network Information Centre.
Application Service Provider (ASP) A company that provides access, via the Internet, to applications and other services that would otherwise have to reside on a local computer.
ARIN American Registry for Internet Numbers.
ARP Address Resolution Protocol.
ARPANET Advanced Research Projects Agency Network.
AS Autonomous System.
AS Number An identifying number allocated to an Autonomous System by an RIR.
Asia Pacific Network Information Centre (APNIC) The RIR responsible for Asia Pacific region. See also: ARIN, RIPE NCC.
ASP Application Service Provider.
AUP Acceptable Use Policy.
Autonomous System (AS) An IP network, or set of IP networks, with a single (i.e. autonomous) routing policy.
BGP Border Gateway Protocol.
BGP4 BGP Version 4. The version of BGP currently being used, as defined by RFC 1771.
Binary Digit A digit to base 2, i.e. 0 or 1, which is the fundamental mathematical unit used in computing.
Bit Binary Digit.
Border Gateway Protocol An Internet Standard protocol defining the way in which Autonomous Systems exchange routing information.
Browser Web browser
Byte 8 bits of data, sometimes called a "word" or and "octet"
Cat5 Category 5 cable.
Category 5 (Cat5) A specification of twisted pair (UTP) copper cable to meet the criteria required by 100baseT.
cc Country code.
ccTLD Country code top level domain. The last part of a domain name using a cc allocated to a specific country. E.g. .uk " United Kingdom, .nl " Netherlands etc. signifying the country in which the domain is registered and usually, but not always, indicating where the holder of the domain name is based. See also gTLD, second level domain, Nominet.
CDP Cisco Discovery Protocol
Cisco Discovery Protocol (CDP) A proprietary Cisco protocol for discovering devices on a network. CDP compatible devices send periodic messages to a multicast address. Devices discover each other by monitoring announcements made on that address.
Co-location The renting of space for housing computer equipment, usually in specially designed buildings (sometimes called telehouses or carrier hotels). The space is often shared with other tenants, hence the term.
Content A fairly loose term for material stored on a server e.g. Web pages on a Web server.
Country code (cc) A two-letter code uniquely identifying a country. Standardised by ISO3166-1.
Dense Wave Division Multiplexing (DWDM) A technology that enables data from different sources to be transmitted simultaneously on a single optical fibre, each signal (data source) being carried on a discrete optical wavelength. Up to 80 (and theoretically more) wavelengths can be transmitted on a single optical fibre.
DNS Domain Name System.
Domain Name A name, registered with, and held on a database by one of various agencies, consisting of a name, sometimes a second level domain and a top level domain. E.g.,
Domain Name System (DNS) A distributed database, and the operating software, holding records associating domain names with IP addresses. Most ISPs run DNS for their customers, the records held allow a computer somewhere else on the Internet making an enquiry of the DNS server to find the translation from a human friendly domain name to an IP address that is understandable by a computer, e.g. to
Downstream Transit The provision of (usually at a cost) access to the global Internet to a third party individual, company or ISP. Not to be confused with a peer. See also Transit, Upstream Transit, Peer.
DWDM Dense Wave Division Multiplexing
Ethernet A LAN protocol developed by Xerox Corporation in cooperation with DEC and Intel in 1976.
Euro-IX European Internet Exchange Association
Extranet Extension of an intranet to an environment outside the boundary of the LAN on which the intranet is running. This is sometimes via the public Internet, or via private circuits. E.g. an internal corporate purchasing system that connects to, and exchanges data with external suppliers systems to place orders etc.
Fast Ethernet A version of Ethernet, supporting data transfer rates of 100 Mbps.
FQDN Fully Qualified Domain Name.
Fully Qualified Domain Name A domain name that is complete and can be translated to a single IP address by DNS, e.g., meaning a machine called "www" in the domain "euro-ix", which in turn is in the gTLD ".net".
Gbps A data transfer rate of Giga (thousand million) bits per second. (Also Gb/s)
generic Top Level Domain (gTLD) The last part of a type of domain name that is not associated with a specific ccTLD. There are 7 in common usage, (.com, .org, .net, .edu, .gov, .mil, .int). Originally they signified the nature of the organization using it:- .com - commercial company, .org - organization, usually non-profit making, .net - companies and organizations involved with the infrastructure of the Internet, .edu - educational (usually US), .gov - governmental (usually US), .mil - military (usually US), .int - international company or organization, however the use of some, particularly .net and .org is no longer limited to a particular type of organisation. A further 6 gTLDs have more recently come into use. These are:- .aero - for the air transport industry, .biz - for businesses, .coop - for co-operative associations (not chickens), .info - not restricted to any particular type of organisation, .museum - for, unsurprisingly, museums, and .name - for individuals. As they are all independent of a particular country, they are also sometimes called global Top Level Domains. See also ccTLD, second level domain
Gigabit Ethernet (GigE) A version of Ethernet later still than Fast Ethernet, supporting data transfer rates of 1 Gbps.
GigE Gigabit Ethernet
Global Routing Table All the routes(2) available in the public Internet, called a "Table" since they are held by routers in a tabular fashion. As of February 2002 the global routing table has approximately 110,000 routes(2), however some of these are duplicates, or erroneous and the true size is probably between 95,000 and 100,000.
gTLD generic Top Level Domain.
Hosting A loose term for the function of holding and sometimes managing servers
IAB Internet Architecture Board.
IANA Internet Assigned Numbers Authority.
ICANN Internet Corporation for Assigned Names and Numbers.
ICMP Internet Control Message Protocol.
IEEE Institute of Electrical and Electronical Engineers.
IETF Internet Engineering Task Force.
Institute of Electrical and Electronic Engineers (IEEE) A technical professional society promoting the development and application of electro-technology and allied sciences for the benefit of humanity, the advancement of the profession, and the well being of its members. It also draws up specifications for standards in the industry, for which it is probably best known.
Interface The hardware and software required to connect one piece of computer or communications equipment to another.
Internet The name given to the millions of interconnected connected devices and networks around the globe using a common protocol (IP)
Internet Architecture Board (IAB) A technical advisory group of the Internet Society providing (amongst other things) architectural oversight, standards process oversight and appeal, management of the RFC document series, administration of IANA, representation of the interests of the Internet Society in liaison relationships with other organizations and a source of advice and guidance to the Board of Trustees and Officers of the Internet Society.
Internet Assignment Numbers Authority (IANA) An organization which had responsibility for some of the functions of ICANN. Some functions are still in the process of being transferred, therefore there is some confusion as to which functions still lie with IANA and which with ICANN.
Internet Control Message Protocol (ICMP) A message and control and error reporting protocol between IP devices. One example of an application using ICMP is 'ping', which sends a sequence of packets to another device requesting a response. The resulting response, or lack of, enable the application to measure success rate and round trip time.
Internet Corporation for Assigned Names and Numbers (ICANN) A non-profit corporation formed to assume responsibility for the IP address allocation to the RIRs, protocol parameter assignment, domain name system management, and root (name) server system management functions previously performed under U.S. Government contract by IANA and other entities.
Internet Engineering Task Force (IETF) An open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. It is open to any interested individual.
Internet Exchange (IX) A physical infrastructure allowing many ISPs to exchange Internet traffic. Traffic is exchanged by peering agreements made between the ISPs connected to the Internet Exchange. By peering at an Internet Exchange the connected ISPs reduce their reliance on a small number of networks (usually their upstream provider(s)), and this improves the delivery and receipt of traffic. This increase in efficiency benefits the connected ISP, and all its customers. The costs involved in connecting to an Internet Exchange are generally quite low for the improvement in performance that can be achieved. Most European Internet Exchanges are non-commercial co-operatives funded by membership fees paid by the connected ISPs, and are operated for the benefit of the member ISPs and the Internet community at large. See also: IXP, NAP.
Internet Exchange Point (IXP) An alternative term for Internet Exchange.
Internet Protocol (IP) The communications Protocol used on Internet networks.
Internet Research Task Force (IRTF) An open international community to promote research of importance to the evolution of the future Internet by creating focused, long term and small research groups working on topics related to Internet protocols, applications, architecture and technology.
Internet Service Provider (ISP) A company or organisation that connects end-users and businesses to the public, global Internet. ISPs often provide other services such as storing and forwarding email, and hosting web sites for their customers.
Internet Societal Task Force (ISTF) An open organization of people who are committed to furthering the mission of The Internet Society to assure the open development, evolution and use of the Internet for the benefit of all people throughout the world.
Internet Society (ISoc) A non-profit, non-governmental, international, professional membership organisation. The work of the Internet Society focuses on Internet standards, public policy, education and training, and membership.
Internet Standard A document from the RFC series that has been accepted by the Internet Community as an industry wide standard. See:
Intranet A closed user group network of devices using IP, often limited to within one organisation or company.
Internet Protocol.
IP Address A unique identifier for a device on the Internet, usually expressed as 4 sets of numbers in the range 0 " 255 separated by dots, (known as "4 octets in "dotted decimal" notation" e.g. 192 254.166.25).
IP network A network using Internet Protocol.
IP Packet A discreet 'chunk' of Internet traffic, between 40 and 1599 bytes long, having source, destination (i.e. routing information) and other management information as well as the actual user's data (the 'payload'). Because an IP packet carries routing information it can be treated by the IP network independently to any other IP packets, regardless of whether they are carrying related traffic.
IRTF Internet Research Task Force.

Internet Society.

ISP Internet Service Provider.
ISTF Internet Societal Task Force.
IX Internet Exchange.
IXP Internet Exchange Point.
Kbps A data transfer rate of Kilo (thousand) bits per second. (Also Kb/s)
LACNIC Latin America and Caribbean Network Information Centre.
LAN Local Area Network.
Latin America and Caribbean Network Information Centre (LACNIC) An emerging RIR responsible for Latin America and the Caribbean Africa, which is currently covered by ARIN.
LIR Local Internet Registry.
Local Area Network
(LAN) A network of computers spread over a relatively small physical area, often in one building and often belonging to one organization. See also MAN, WAN
Local Internet Registry (LIR) A company or organisation (usually an ISP that has been allocated a block of IP addresses by a Regional Internet Registry to assign to its IP customers or users and its own IP network.
MAN Metropolitan Area Network.
Mbps A data transfer rate of Mega (million) bits per second. (Also Mb/s)
Metropolitan Area Network (MAN) A network of computers spread over a metropolitan area. MANs may be operated by one organization e.g. a corporate with several offices in one city, or be shared resources used by several organisations, e.g. an IX with several locations in the same city. See also LAN, WAN.
Multihome The connection of an IP network to two or more AS numbers, i.e. connection to two or more upstream transit provider IP networks. A configuration often used by ISPs to give resilience and improve IP network performance.
NAP Network Access Point.
Network Two or more interconnected computers or data communications devices See also IP Network, LAN, MAN, WAN.
Network Access Point (NAP) A term used mainly, but not exclusively, in the US for an IX.
Nominet UK The Registry and maintainer of the database(s) for .uk cc Internet domain names. See also gTLD, ccTLD, second level domain.
Packet A discreet "chunk" of data traffic.See IP Packet.
Peer An ISP with which one has a peering relationship.
Peering A business relationship whereby ISPs provide to each other connectivity to each other"s downstream transit customers. The terms peering and peer are often, particularly in the US, used to refer to the relationship with downstream transit customers and upstream transit providers.
Protocol A set of rules governing the way in which two networked devices will communicate with each other. E.g. routers exchange routing information using the BGP protocol, at a more fundamental level all Internet devices exchange traffic using Internet Protocol.
Réseaux IP Européens (RIPE) A collaborative organisation open to organisations and individuals operating wide area IP networks in Europe and beyond. The objective of RIPE is to ensure the administrative and technical coordination necessary to enable operation of a pan-European IP network.
Réseaux IP Européens Network td Centre (RIPE NCC) The RIR responsible for Europe, The Middle East, The North of Africa and parts of Asia regions. RIPE NCC also performs administrative and technical support functions for RIPE See also: APNIC, ARIN.
Regional Internet Registry (RIR) An organisation which is allocated large blocks of IP addresses by ICANN, for re-allocation to Local Internet Registries. Currently there are 3 Regional Internet Registries, ARIN, APNIC and RIPE NCC. There are also some new RIRs emerging including, AFRINIC and LACNIC.
RFC Request For Comment. A series of notes, started in 1969, about the Internet (originally the ARPANET). The notes discuss many aspects of computer communication, focusing on IP networking protocols, procedures, programs, and concepts but also including meeting notes, opinion, and sometimes humour.
RIPE R"seaux IP Europ"ens.
RIPE NCC R"seaux IP Europ"ens Network Coordination Centre.
RIR Regional Internet Registry.
Root name server A server which is the point of last resort in the DNS system. The root name servers hold a database of the location of further DNS servers which are responsible for holding the database of a top level domain, that is the part of a domain name after the last dot. (In computing terms there is always a dot at the very end of a domain name, which is 'assumed' by most software so it rarely seen, but this is why these servers are sometimes called 'dot' servers). There currently 13 root servers around the world, with the domain names '',' etc to ''. Somewhat confusingly there are also currently 13 Domain name servers for the gTLDs, named '', '' etc to '', and these are often incorrectly referred to as root name servers.
Route(1) The actual route taken by IP packets on the Internet.
Route(2) A specific destination IP network, (a group of contiguous IP addresses) on the Internet. A destination IP network may be small or large. All the routes2 available on the public Internet make up the Global (or World) Routing Table
Router A device on the Internet that receives IP Packets and sends them to the next device on the way to their final destination. Routers make intelligent decisions on which device to route the IP packets to based on dynamic routing information exchanged with other routers on the Internet.
Routing Information Data exchanged between devices, mainly routers, on the Internet. Amongst other information, one router will tell (or 'announce to') other routers on the Internet the routes(2) that it can 'see', (i.e. the routes(2) it is able to send IP packets to and receive IP packets from) either directly or via another router. Other routers 'listen' to this information, and build a database (a routing table) of which routers can 'see' which routes(2), and from this can make intelligent decisions about where to send any particular IP packet.
Routing Registry database A database, maintained in Europe by RIPE NCC, holding ISPs routing policies
Routing Table A database of routing information held by routers.
Second Level Domain A level below a gTLD or ccTLD. E.g. the ."co" in " Organizations responsible for registrations of domain names in certain ccTLDs, such as Nominet in the UK have decided to use second level domains to provide a greater range of options within that ccTLD.
Tier 1 ISP See Tier Hierarchy
Tier 2 ISP See Tier Hierarchy
Tier 3 ISP See Tier Hierarchy
Tier Hierarchy A hierarchical model of the relationships between ISPs. Tier 1 ISPs are large and together hold all the world"s Internet routes(2), and peer with each other to give each other access to all Internet routes(2). Tier 2 ISPs buy connectivity (upstream transit) to the world Internet routes(2) from one or more tier 1 ISPs, and hence their IP network(s) becomes a sub-set of those tier 1"s IP networks. Tier 2 ISPs will also peer with each other to minimize the amount of traffic to and from the tier 1 ISPs from whom they buy upstream transit. Tier 3 ISPs buy upstream transit from Tier 2 ISPs and so on, however the model becomes increasingly vague, since an ISP may buy upstream transit from both a tier 1 ISP and a tier 2 ISP, and may peer with tier 2 and tier 3 ISP"s and occasionally a tier 1 ISP, and so on. The term is really only of use to differentiate between tier1 ISPs who do not need to buy upstream transit due to their peerings with other tier 1 ISPs, and the rest of the ISPs, tier 2 and below.
TLD Top level domain.
Top Level Domain (TLD) The "highest" part of a domain name, being either a gTLD or a ccTLD.
Transit A term used generally, but not exclusively, to describe the routing of Internet traffic between an IP network and the public Internet. It is a service sold by ISPs to other ISPs, corporates and home users. This service is also called Upstream Transit, Internet Connectivity, Internet Access and, particularly in the home user market, Dial-up Access where the connection to the ISP is often made by a modem dialing the ISP over a standard telephone line. See also Upstream Transit and Downstream Transit.
u A unit of measurement of height used mainly in relation to computer and related equipment and the racks in which they are fitted. 1u is 1.75 inches, or 4.445 centimetres.
Unshielded Twisted Pair (UTP) A type of data cable containing four pairs of conductors, each pair being twisted together. UTP is used extensively in connecting IP network devices together.
Upstream Transit The provision of (usually at a cost) access to the global Internet from an ISP. See also Transit, Downstream Transit.
UTP Unshielded Twisted Pair.
WAN Wide Area Network.
Wide Area Network (WAN) A network of computers spread over a large physical area, from regional to global. WANs may be operated and used by single organizations, or used by many. Perhaps the ultimate WAN is the Internet. See also LAN, MAN.
World Routing Table Another term for Global Routing Table.