Glossary of Networking Terms

10BaseT Protocol used to support 10Mbit/s Ethernet over UTP cabling.
100BaseT Protocol used to support 100Mbit/s fast Ethernet over Category 5 UTP cabling.
100BaseT4 Protocol used to support 100Mbit/s fast Ethernet over category 3 UTP cabling using 4 pairs.
1000BaseT 1000 Mbit/s Ethernet, Gigabit Ethernet over category 5 UTP cabling using 4 pairs.
ACD Automatic Call Distribution.  This is the term for equipment which is employed to distribute telephone calls between a group of answering agents.  It may be an inherent part of a PABX or an add-on system.  ACD is used extensively in Call Centre environments.
ATM Asynchronous Transfer Mode.  This is a networking protocol which can support multimedia (i.e. Voice, data, video, text etc.) communications.  It was initially developed as a wide area protocol for use by the major public carriers (e.g. BT Mercury etc.).  However, it is now commonly used as a local area backbone protocol in private networks.  ATM will ultimately provide connectivity right to the desktop.
Backbone Term used to refer to the common central elements of any communications network.  The backbone is the part of the network which connects all the individual network components. 
Bridge A bridge is used to provide traffic separation between two elements, or segments, of a local area network.  Local bridges connect two adjacent networks whilst remote bridges utilise leased lines to interconnect networks which are remote from one another.
Centrex Product name used to describe a PTO provided telephone service.  With such a service, all users telephone extensions are connected directly to the PTO’s equipment.  This eliminates the need for a PABX.
CLI Calling Line Identity.  The term used to describe the feature whereby the telephone number of a calling party is presented to the equipment of the called party.
Client/Server A term used to describe the relationship between computing hardware.  In a typical network, user PCs are referred to as clients which communicate with a central server device.  The server generally provides common services to many clients.
CTI Computer Telephony Integration.  The integration of computer and telephone systems to support intelligent applications.  At its simplest this might be the ability to support a simple telephone from a PC.  Conversely CTI is used extensively in Call Centres to co-ordinate the transfer of telephone calls with associated database details applicable to the caller.
DASS2 Digital Access Signaling System 2.  A signaling system employed to enable PABX systems to communicate with public switches.  BT’s ISDN30 service can utilise DASS2 signaling which is a feature rich version of Euro ISDN30. 
DDI Direct Dialing Inward.  This facility enables external callers to dial directly to PABX extensions (without going via the switchboard) by inserting a prefix in front of the extension number.
Dial-up A term used to refer to applications which utilise analogue (dial-up) modems to access remote systems.
DPNSS Digital Private Network Signalling System.  The standards based signalling system employed in the UK to enable two PABX’s to communicate via digital private circuits.
e-mail Electronic mail. The generic term used for any electronic messaging system which enables users to exchange information via networks.  EMail may refer to either closed user group systems on private networks or wide area systems such as the internet.
Ethernet  A local area networking protocol.  Ethernet was designed as a common bus system operating at 10Mbit/s.  However, Ethernet hubs are commonly used to support a star based topology over UTP whilst a 100Mbit/s variant (fast Ethernet) is also now available.
FDDI Fibre Distributed Data Interface.  FDDI is a 100Mbit/s networking protocol which operates over optical fibre.  FDDI was initially developed as a MAN protocol but is also commonly supported in the LAN environment.
Gateway A term used for a device which enables two networks to communicate with each other.  The term strictly refers to a device which undertakes a protocol conversion between two non-like networks.  However, it is now commonly applied to any device which acts as an access point between networks even if no protocol conversion is necessary (e.g. internet gateway).

A device which is utilised to connect multiple other devices. The most common application is an Ethernet hub which is used to support star based Ethernet topologies.

http Hyper Text Transfer Protocol, used for WWW documents.
Internet The term applied to the global common access computer network.  The internet is the global equivalent of the public telephone network.  However, whilst the telephone network provides dedicated secure communications between users, the internet relies upon shared bandwidth.
Intranet A closed user group internet which uses browser style interfaces to present information.  An intranet may either exist only within a private network or may be accessible via the internet.
IP Internet Protocol. Now becoming the dominant protocol for WANs and LANs.
ISDN Integrated Services Digital Network.  The ISDN is the modern, digital equivalent of the PSTN. It employs digital technology throughout and can be used to support multimedia communications including voice, data, video and image.  Two narrow band ISDN products are commonly available in the UK; basic rate (2B+D, 144Kbit/s, ISDN2) and primary rate (30B+D, 2Mbit/s).  Broadband services will become available in the future. ISDN2e is BT’s European ISDN 2B+D service. 
ISDX The product name for a PABX manufactured by GPT.
ISP Internet Service Provider.  Companies who provide access to the internet.  Access may be via dial-up modems basic rate ISDN or digital leased lines.
IT  Common abbreviation for the generic term “information technology” used to describe any aspect of computing and networking.
Key system Small telephone system where multiple exchange lines can be presented on each telephone. Key systems usually use telephones/terminals that are exclusively designed for a particular system.
LAN Local Area Network.  Generally refers to the network within a single building although LAN protocols will operate up to 2,000m over optical fibre.
Leased Line A circuit rented from a PTO.  A leased line provides permanent guaranteed bandwidth between two locations.
MAN Metropolitan Area Network.  Strictly a term used to define a network throughout a metropolitan area.  Such a network would generally be PTO provided.  However the term is now commonly used to describe an extended LAN which serves a number of buildings in a restricted geographical area.
NMS Network Management System.  Any system used to monitor, administer and manage networking components.  Historically used for data networks but can now include voice systems. 
OFTEL Office of Telecommunications. The Government appointed watchdog organisation in the UK.
PABX Public Automatic Branch Exchange.  The term used to describe an organisations privately run internal telephone system. 
PC Personal Computer.  A workstation with integral processing power located at the desktop.  PCs can operate as standalone devices but are commonly networked.
Peer-to-peer Refers to a network topology where devices communicate directly with each other rather than according to a client server architecture.  Resource sharing under Windows95 is an example of peer to peer networking.
PTO Public Telecommunications Operator.  Companies providing telecommunications services (e.g. BT, Mercury etc.).
RAS Remote Access Server.  A device which enables external devices to access network facilities.  The RAS will generally be equipped with analogue modems and/or ISDN terminal adapters to enable remote users to “dial-in”.  The RAS will incorporate security features including password control, dial back, CLI recognition and hardware handshaking.
Router A device which controls the routing of information on a network.  The term strictly refers to a layer 3 (OSI model) device which can interpret network addressing information and route data packets accordingly.  Routers undertake broadly the same function as bridges but can dynamically manage bandwidth more effectively and can provide enhanced levels of security.
SLA Service Level Agreement.  A term commonly used within the IT industry to refer to the service standards which a service provider agrees to deliver to a user.  Initially used in contractual arrangements with third parties but now commonly used as an internal agreement within organisations.
SMTP Simple Mail Transfer Protocol.  The protocol used to exchange mail between an organisations email system and the internet.
SNMP  Simple Network Management Protocol.  The protocol used by devices to communicate with a network management system. 
Switch Generic term for a PABX.  Also a device employed in LANs to partition networks.  A LAN switch (Ethernet or token ring) is strictly a matrix of bridges that isolates Ethernet collision domains. 
TCP Transmission Control Protocol. Often used as a suite with IP as TCP/IP with jointly forms the protocols used on the Internet.
U Height Equates to 1.75 inches and is used to measure vertical Usable space in IT equipment cabinets. Most IT equipment is sized in U’s.
UTP Unshielded Twisted Pair cabling.  A type of cable employed in structured cabling schemes.  Can be used to support multimedia communications (voice, data, video etc.) at distances of up to 100m with bandwidths of up to 155Mbit/s (ATM).
Voicemail The generic term used to describe voice messaging systems.  The systems can support a wide range of applications ranging from personal voice mailboxes to automated attendant systems.
WAN Wide Area Network.  The term used to describe any network which is not restricted to a limited geographical area.


World Wide Web  The network of information servers attached to the internet. Organisations can present information on web sites which can be accessed by any user attached to the internet.


  Copyright Ó annor Ltd   2004