IP SOLUTIONS / INTEGRATED SYSTEMS - Glossary
In recent years, the demand for fully integrated security solutions has grown dramatically. With the emergence of IP compatible security products, it is now possible for the specialist security installer to provide such solutions across existing LAN & WAN networks.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
ARMOUR - Extra protection for a cable that improves resistance to cutting and crushing. The most common material used is steel.
ARP (ADDRESS RESOLUTION PROTOCOL) - Maps an IP Address to a physical machine address (MAC).
BACKBONE - A high-capacity network that links together other networks of lower capacity. A local backbone network would typically be an FDDI network acting as an in-building backbone to link together multiple LANs.
BALUN - A transformer that levels out impedance differences, so that a signal generated on to a coaxial cable can be transferred on to a twisted pair cable.
BANDWIDTH - The range of frequencies a transmission line or channel can carry: The greater the bandwidth, the greater the information-carrying capacity of a channel. For a digital channel this is defined in bit/s.
BASEBAND - A transmission medium through which digital signals are sent without frequency shifting. In general, only one communication channel is available at any given time. Ethernet transmission is a form of baseband.
10Base2 - A form of Ethernet and IEEE 802.3 network cabling using thin coaxial. It refers to 10Mbit/s speed baseband transmission over 200 meters maximum length (in practice 185m) and is commonly known as Cheapernet.
10Base5 - A form of Ethernet and IEEE 802.3 network cabling using thick coax. It refers to 10Mbit/s speed baseband transmission and 500m maximum length.
10BaseF - A form of Ethernet and IEEE 802.3 network cabling using optical fibre. It refers to 10Mbit/s speed baseband transmission over a couple of kilometres for multimode to tens of kilometres for single mode fibre.
10BaseT - A form of Ethernet and IEEE 802.3 network cabling using twisted pair cabling. It refers to 10Mbit/s speed baseband transmission twisted pair cable with a maximum segment length of 100m.
100BaseT - IEEE standard from proposals by the Fast Ethernet Alliance (including 3Com and Syn-Optics). It will support Category 3, 4 & 5 UTP cabling.
BIFURCATOR - An adaptor with which a loose tube containing two optical fibres can be split into two single fibre cables. (See loose tube).
BIT - Single digit of binary notation. Expressed as a 0 or 1.
BITS PER SECOND - The rate at which individual bits are transmitted across a communications link or circuit; written bit/s. One thousand bit/s is 1 Kbit/s, and one million bit/s is 1 Mbit/s.
BNC - Video connector used in CCTV installations.
BOOT - A protective cover placed over an RJ45 plug. Provides addition strain relief and protection for the plug latch.
BRIDGE - Device connecting two separate networks. Once bridging is accomplished, the bridge makes interconnected LANs look like a single LAN, passing data between the networks and filtering local traffic.
BROWSER - Software program that allows a webpage to be viewed.
BUFFER - The material surrounding the fibre to protect it from physical damage.
BYTE - A group of eight consecutive bits (8 bits = 1 byte).
CATEGORY 5 - Cabling standard specified by EIA/TIA 568 for use with speeds up to 100Mbit/s including FDDI (TP PMD), 100BaseT and 100BaseVG-AnyLan, and potentially ATM at 155Mbit/s.
CATEGORY 6 - Cabling standard specified by EIA/TIA 568-B.2-1, offering performance parameters that are vastly improved over the TIA/EIA category 5e standard for use with speeds upto 1Gbit/s.
CATEGORY 7 - Not yet ratified.
CLADDING - The outermost region of an optical cable, less dense than the central core. Acts as an optical barrier to prevent transmitted light leaking away from the core.
CLIENT / SERVER - Describes the relationship between two computer programs in which one program, the Client, makes a service request from another program, the Server, which fulfils the request. Although the Client/Server idea can be used by programs within a single computer, it is used more in a network. In a network, the client/server model provides a convenient way to interconnect programs that are distributed efficiently across different locations.
CORE - The central region of an optical fibre through which a signal carrying infrared is transmitted. Manufactured from high-density silica glass.
CROSSED PAIR - A crossed (or transposed) pair is a wiring fault where wires of a pair are connected at the remote end to the pin locations allocated for a different pair.
CROSSOVER CABLE - A crossover cable is a cable that is used to interconnect two computers by "crossing over" (reversing) their respective PIN contacts.
CROSSTALK - Unwanted interference from another adjacent communications channel.
DB (DECIBEL) - A logarithmic ratio between two signals. It is used as the unit of noise or signal strength.
DHCP (DYNAMIC HOST CONFIGURATION PROTOCOL) - Automatic allocation of IP Addresses.
DNS (DOMAIN NAME SERVER) - An Internet service that translates domain names into IP addresses. For example, the domain name www.name.com may translate to 198.105.232.4
DRAIN WIRE - An un-insulated wire in contact with a shield throughout its length. Used for terminating the shield in FTP/STP cable installations.
EIA - The American 525 line standard for the video signal.
EIA/TIA - The US Electronics Industries Association and Telecommunications Industries Association, which have merged. The EIA is a US trade organisation for the electronics industry that concentrates on hardware interface standards.
EIA/TIA 568 - The EIA/TIA's most famous standard specifying a maximum horizontal cable run of 90 meters, allowing 10 meters for hub and device attachment resulting in a total cable length.
EMC (ELECTRO-MAGNETIC COMPATIBILITY) - This is extent to which a piece of hardware will tolerate electrical interference from other equipment, and will interfere with other equipment.
ETHERNET - The most widely used LAN transmission network. Based on a bus network topology, it runs at a maximum speed over 100 meters of 10Mbit/s. It operates over conventional co-axial cable, thin wire co-axial cable and unshielded twisted pair cabling. This has several implementations - 10Base5 for use over conventional co-axial cable, 10BaseF for use over optic fibre, and 10BaseT for use over Unshielded Twisted Pair (UTP) cabling.
FAST ETHERNET - Proposed 100Mbit/s technology for workstation LANs.
FEXT (FAR END CROSSTALK) - The interference caused in a pair at the receiving (Far) end caused by the transmission of a signal in another pair.
FIREWALL - Either hardware or software that protects a network from outside intrusion.
FLOOD WIRING - The installation of many data outlets and cable runs that is actually required at the time by the user. These additional outlets are left unused for future expansion of the system.
FTP (FILE TRANSFER PROTOCOL) - Simplest way to exchange files between computers and the Internet.
FTP (FOIL SCREENED TWISTED PAIR) - Sometimes referred to as STP (Shielded Twisted Pair). This cable is constructed similar to UTP but is enclosed in a sheath of aluminum foil for EMC protection. The disadvantage of FTP is that it requires somewhat more care in "earthing" (grounding) than UTP and electrical impedances must be matched when connecting to UTP. Typically, FTP might be used in a factory setting and UTP in an office setting.
GATEWAY - A node that allows connection to another network using another protocol.
GRADED INDEX (GRADED INDEX PROFILE) - A measurement, shown in the form of a diagram, which illustrates how the quality of glass used in optical fibre alters gradually, from densest at the core to the optically less dense cladding.
HARDWIRED - Direct cables connected from one electronic product to another. Can be labour intensive to install and is only used in simple systems with short cable runs.
H COMPRESSION (H261, H263, H321 & H324) - Offering a high frame rate, low image quality, these compression techniques are popular for video conferencing applications. The low image quality is particularly acute when the image contains moving images.
HEXADECIMAL - Base 16 number system ranging from 1,2,3,4,5,6,7,8,9,10,A,B,C,D,E,F
HERTZ (Hz) - The number of variations per second (e.g. picture frames, alternating of the current, etc).
HTML (HYPERTEXT MARKUP LANGUAGE) - A set of symbols or codes inserted into a file intended for display on a world wide web browser.
HTTP (HYPERTEXT TRANSFER PROTOCOL) - A set of rules for exchanging files (text, graphics, sound, video etc) on the World Wide Web.
HUB - The centre of a star topology network or cabling system. A multi-node network topology, that has a central multiplexer with many nodes feeding into and through. The other nodes do not usually directly interconnect. LAN hubs are increasingly popular with the growth of structured cabling and the need for LAN management.
IDC (INSULATION DISPLACEMENT CONNECTOR) - A screwless connector for terminating wires without first having to strip the insulation from the wire.
IMPEDANCE - A measure of the total opposition to current flow in an alternating current circuit, measured in Ohms (O).
IP (INTERNET PROTOCOL) - The TCP/IP standard protocol that defines the IP datagram as the unit of information passed across an Internet and provides the basis for connectionless packet delivery service.
IP ADDRESS - The 32-bit address assigned to hosts that want to participate in a TCP/IP Internet.
IP DATAGRAM (PACKET) - The basic unit of information passed across a TCP/IP Internet.
ISDN (INTEGRATED SERVICES DIGITAL NETWORK) - A higher transmission speed for telephone circuits, which allows video signals to be transmitted at speeds of 128Kb/second: used with terminal adapters.
JACK - An RJ45 outlet module socket.
JPEG - A popular compression standard for still images. Native to most web browsers, this is the preferred image standard for many Network cameras.
JPEG2000 - A new compression medium but as yet uncommon standard, based on Wavelet technology.
LAN (LOCAL AREA NETWORK) - A communications system that links computers into a network, usually via a wiring based cabling scheme. LANs connect PCs, workstations and servers together to allow users to communicate and share resources like hard disk storage and printers. Devices linked by a LAN may be on the same floor or within a building or campus. It is user-owned and does not run over leased lines, though a LAN may have gateways to the PSTN or other private networks.
LINE ADAPTER - A plug in device for converting from a standard RJ45 outlet module to other format sockets eg. BT, RJ11 etc.
LINE AMPLIFIER - A device to make good the loss of signal strength and quality due to long cable runs.
LOOSE TUBE - This refers to a type of cable in which one or more optical fibres are laid loosely within a tube.
MAC ADDRESS (MEDIA ACCESS CONTROL) - This the unique physical address of the network interface card created at the manufacturing stage. It is usually stated as the serial number expressed in hexadecimal format of 12 bytes.
MAN (METROPOLITAN AREA NETWORK) - A high-speed network designed to link together sites in a metropolitan or campus area.
MICROWAVE TRANSMISSION - Another method of transmitting video signals and telemetry signals over free space. This is less affected by weather conditions and transmits over longer distances. Most countries require a licence to use this method.
MJPEG - This compression standard generally refers to JPEG images shown at high frame rate, generally 30 frames per second. It gives high quality video images, but the comparatively large file sizes of each individual image does put demands on the transmission bandwidth.
MODE - (In fibre optics) The path taken by a light ray as it travels along a fibre.
MPEG1 - The video standard that typically delivers 30/25 (NTSC/PAL) frames per second. With many variations, this format provides low-resolution images but places low demand on the transmission medium.
MPEG2 - Compression offers higher resolution images and same frame rates as MPEG1. Only modern computers can decode this format, as it generally demands high computing capacity.
MPEG4 - A video compression standard that offers high performance video with good resolution and moderate demand on transmission bandwidth. Most MPEG4 solutions today, however, are focused on high-end applications, since they are very costly.
MULTIMODE FIBRE - An optical fibre that allows the signal carrying light to travel along more than one path.
NEXT (NEAR END CROSSTALK) - The interference caused in a pair at the transmission (Near) end caused by the transmission of a signal in another pair.
NETWORK ADAPTER CARD - A printed circuit board, installed in a computer, enabling the computer to be joined to the LAN.
NODES - Devices on a network where transmission paths are connected. The node term is often used instead of workstation.
NOISE - This is inherent in all electronic circuits. In a video signal this appears as snow or graininess in the picture.
OPTICAL BUDGET - The total attenuation (expressed in decibels - DB) of a system to function satisfactory. Ranges of optical loss depend upon connector, fibre and splice types. The higher the number in DB's of Optical Loss, the further the system will function.
PABX (PRIVATE AUTOMATIC BRANCH EXCHANGE) - An automatic telephone switching system within a private enterprise.
PATCH LEAD - A flexible piece of stranded data cable terminated with RJ45 plugs at both ends. Used for interconnecting circuits in a cabinet between patch panels and hubs: also for connecting between the RJ45 outlet module and end user equipment.
PBX (PRIVATE BRANCH EXCHANGE) - A telephone exchange local to a particular organisation who use, rather than provide, telephone services.
PHOTO DETECTOR - A device at the receiving end of an optical fibre link that converts light to electrical power.
* PING (PACKET INTERNET GROPER) - A small DOS based program that tests if an IP Address is referenced to a MAC address. A message is sent to the IP Address and the response timed. Errors occur in IP Address, Subnet Mask, Default Gateway, return path, hardware or software faults.
PORT - A computer interface that can be used to attach another device, such as a modem, for communicating with a remote terminal or, if the port is within a hub, to a workstation.
PPP (POINT TO POINT PROTOCOL) - Is the Internet standard for transmitting IP datagrams's (IP packets) over serial point-to-point links, typically standard telephone lines, ISDN and other high-speed connections.
PRIMARY COATING - A thin plastic coating applied to the outer cladding of an optical fibre. This is essential to protect the fibre from contamination and abrasion.
PROXY SERVER - A server that acts as an intermediary between a workstation user and the Internet. A proxy server is associated with or part of a gateway server that separates an enterprise network from the outside. A proxy server normally contains a firewall.
PSTN (PUBLIC SWITCHED TELEPHONE NETWORK) - The telephone network provided by both BT and Mercury through which video, data or audio signals can be sent.
REGENERATORS - Devices placed at regular intervals along a transmission line to detect weak signals and re-transmit them. These are seldom required in fibre optic systems. (Often incorrectly referred to as 'repeaters').
RJ11 - Popular name for the standard four-wire modular connector for phone connections.
RJ45 - Popular name for the eight-pin modular connector used in the 10BaseT standard for UTP connections, to connect workstations or smart wiring hubs.
ROUTER - Router Network interconnector device. A router can be used to link LANs together locally or remotely as part of a WAN. A network built using routers is often termed an internetwork.
SCART - A standard European 20 pin connector, used for carrying both audio and video signals in domestic TV appliances. The majority of modern televisions and VCRs have a scart connector on them.
SCRIPTING - The process of giving a computer commands and parameters to process. Scripting is similar to programming languages but is less powerful. Scripting allows a non-programmer to implement powerful commands without needing to understand the underlying fundamentals of the language.
SHEATH - The outer finish of a cable. Usually this consists of an extruded layer of PVC or polyethylene.
SILICA GLASS - The exceptionally pure glass used to make an optical fibre.
SINGLE MODE FIBRE - An optical fibre constructed in such a way that light travelling along the core can only follow one path. (Also called mono-mode).
SMTP (SIMPLE MAIL TRANSFER PROTOCOL) - A protocol used to transfer electronic mail (email) between computers.
STEP INDEX - (STEP INDEX PROFILE). A measurement shown in the form of a diagram which illustrates how the quality of glass used in optical fibre graduates from the highest density to the lowest. The shift from one density to another causes the light to bounce as it travels.
STRAIN MEMBER - The part of an optical fibre cable that removes any strain on the fibres. Commonly used materials are steel and synthetic yarns.
SUBNET - Determines the size of the immediate network. Usually expressed with either 255 or 0 depending on the network class ie. For Class C Networks, the standard subnet mask is 255.255.255.0
SWITCHED HUB - Short for port-switching hub, a special type of hub that forwards packets to the appropriate port based on the IP packet's address. Since switching hubs forward each packet only to the required port, they provide much better performance.
TCP (TRANSFER CONTROL PROTOCOL) - Provides a reliable transport service for IP packets with error checking and recovery.
TELNET - This is the Internet standard protocol for remote login to another computer.
TIGHT BUFFERED - A type of cable in which the optical fibres are tightly bound.
U SIZES - This is a physical height measurement of approximately 44mm used for 19" Rack Systems. Example U Sizes are illustrated below:
| U Size | Useable internal Height | Examples |
|---|---|---|
| 1U | 44mm | SpriteLite |
| 2U | 89mm | Digital Sprite 2 |
| 3U | 133mm | Standard TimeLapse VCR |
| 4U | 178mm | BX2 |
| 6U | 267mm | |
| 9U | 400mm | |
| 12U | 536mm | |
| 15U | 668mm |
UDP (USER DATAGRAM PROTOCOL) - Fast connectionless transport service. Often referred to as "Fire & forget". UDP has no error recovery.
UPS (UNINTERRUPTIBLE POWER SUPPLY) - A battery, attached to a piece of hardware, for example a server, that provides back up power for conducting an orderly shutdown if the server's normal power supply fails.
URL (UNIFORM RESOURCE LOCATOR) - Is the location of a file (often a web page,) on the World Wide Web. The URL specifies the protocol, full address and filename. Examples are http://www.cso.uiuc.edu/docs/101/url.html Generally only the www.cso.uiuc.edu (web address) is typed into the address bar of a standard web browser.
UTP (UNSHIELDED TWISTED PAIR) - The standard cabling used for telephone lines. The standard IEEE 802.3, 10BaseT, defines use of Ethernet over UTP for rates up to 10Mbit/s. The general LAN medium of choice for the 1990s.
VPN (VIRTUAL PRIVATE NETWORK) - Allows two or more private networks to be securely connected via a public addressed network (typically the web). Security and encryption features of a VPN, allows a secure channel across a public network. VPN's are cheaper than private leased lines.
WAN (WIDE AREA NETWORK) - A network that covers a larger geographical area than a LAN and where telecommunications links are implemented, normally leased from the appropriate PTO(s). Examples of WANs include packet switched networks, public data networks and Value Added Networks.
WAVELET - Compression that is optimised for images containing low amounts of data. The relatively inferior image quality is offset against the low bandwidth demands on transmission mediums.
WORKSTATION - Term used freely to mean a PC, node, terminal or high-end desktop processor (for CAD/CAM and similar intensive applications) - in short, a device that has data input and output and operated by a user.
X10 - A communications "language" that allows compatible products to talk to each other via the existing mains electrical wiring in the home.