Base de connaissance Télécom--V--Telecom Database

Base de connaissances en Télécommunication et Informatique
Knowledge Database about Telecommunication

réalisé par Philippe MOLINIÉ
Version : 1.2 -- 1 Janvier 2000

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V.22 (protocol,communications)

An IUT-T modem protocol which allowed data rates of 1200 bits per second. V.22bis doubled this.

Protocole de communications d'un modem à 1200 bit/s.

V.22bis (protocol,communications)

An IUT-T modem protocol which allowed data rates of 2400 bits per second, twice that of V.22.

Protocole de communications d'un modem à 2400 bit/s.

V.32 (protocol,communications)

The IUT-T standard protocol for modems transmitting at 4800 or 9600 bits per second. V.32bis extended this to 14400 bps. V32 and V.32bis acheive bidirectional data transmission not by having different sets of tones at each end but by subtracting what is sent from what is received.

Protocole de communications d'un modem à 4800 et 9600 bps.

V.32bis (protocol,communications)

V.32 twice. An extension of the IUT-T V.32 modem protocol allowing speeds of 7200, 12000 and 14400 bits per second. The modem should select the appropriate speed according to the current line conditions.(See also V.32ter).

Protocole de communications d'un modem permettant des vitesses de 7200, 12000 et 14400 bps.

V.32ter / V.32terbo (protocol,communications)

An extension of the IUT-T V.32bis modem protocol. While waiting for V.34, many modem manufacturers decided to extendV.32bis to 19.2 kbps. This was known as V.32ter which some marketroids rechristened V.32 terbo which is not only misspelled but misses the fact that V.32ter means the third revision of V.32.

Protocole de communications d'un modem permettant des vitesses de 19200 bps.

V.34 (protocol,communications)

A modem operating at data signalling rates of up to 28 800 bits per second (2400, 2743, 2800, 3000, >3200 and 3429 and up to 28800 bits per second) for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits.

During the lengthy process of approval by IUT-T, many manufacturers released 28.8 kbps modems described as V.FAST. The V.34 recommendation was ratified by ITU-T on 20 September 1994. Rockwell and US Robotics both have seats on the ITU-T, and have both released chip set/BIOS combinations that they feel will meet V.34. V.34 modems will also support V.FC if the manufacturer currently supports V.FC (e.g. Rockwell). Some (all?) V.34 modems will also support line probing.

Ref: IUT-T V 34.

Protocole de communications d'un modem permettant des vitesses de 28800 bps.

V.34bis (protocol,communications)

A draft IUT-T standard for modem transmitting at 33600 bps.

Travaux préparatoires(draft) de l'UIT-T pour un protocole de communications d'un modem permettant des vitesses de 33600 bps.

V.35 (protocol, communications, standard)

The IUT-T standard for data transmission at 48 kilobits per second over 60 - 108 KHz group band circuits. It contains the 34-pin V.34 connector specifications normally implemented on a modular RJ-45 connector.

V.42

An IUT-T standard protocol for error correction between modems which includes MNP up to level 4.

Protocole de correction des erreurs de transmission sur un modem. Support le protocole de correction d'erreur MNP.

V.42bis

An extension of the IUT-T V.42 standard modem protocol to included compression.

Protocole de compression des données en vue de communication sur un modem. Extension du protocole V.42.

VAN

Value Added Network (network)

Réseau à Valeur Ajoutée(RVA) (réseau)

Vannevar

/van'*-var/ A bogus technological prediction or a foredoomed engineering concept, especially one that fails by implicitly assuming that technologies develop linearly, incrementally, and in isolation from one another when in fact the learning curve tends to be highly nonlinear, revolutions are common, and competition is the rule. The prototype was Vannevar Bush's prediction of "electronic brains" the size of the Empire State Building with a Niagara-Falls-equivalent cooling system for their tubes and relays, a prediction made at a time when the semiconductor effect had already been demonstrated. Other famous vannevars have included magnetic-bubble memory, LISP machines, videotex, and a paper from the late 1970s that computed a purported ultimate limit on areal density for integrated circuits that was in fact less than the routine densities of 5 years later.

VBR

Variable bit rate (atm)
Information that can be represented digitally by groups of bits (as opposed to streams) is characterized by a variable bit rate. Most data applications generate VBR traffic,which can tolerate delays and fluctuating throughput.

Débit variable (atm)

VBR-NRT / nrt-VBR

Variable Bit Rate - Non-Real Time (atm)
One of five ATM Forum-defined service types .It is used for transmitting traffic where timing information is not critical and which is characterized by the average and peak cell rates. It is well-suited for long data packets transfers.

VBR-RT / rt-VBR

Variable Bit Rate - Real Time (atm)
One of five ATM Forum defined service types for transmitting traffic that depends on timing information and control and which is characterized by the average and peak cell rates. It is suitable for carrying traffic such as packetized (compressed) video and voice.

VC

Virtual Circuit (network)
A connection set-up across the network between a source and a destination where a fixed route is chosen for the entire session and bandwidth is dynamically allocated on demand by the network as users have traffic to transmit. (see also datagram, SVC, PVC).

Circuit Virtuel
Voie de communication logique, entre deux entités, n'empruntant pas un chemin physique fixé une fois pour toutes, mais un ensemble de ressources dont l'affectation peut-être temporaire(on parle alors de Circuit Virtuel Commuté ou CVC) ou permanente !!(Circuit Virtuel Permanent ou PVC).

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Virtual Connection (network)
A connection established between end-users (source and destination), where packets are forwarded along the same path and bandwidth is not permanently allocated until it is used.

Connexion Virtuelle (réseau,)
Connexion établie entre utilisateurs terminaux(source et destination), où les paquets sont transmis en suivant un même chemin et ou la bande passante n'est pas allouée de manière permanente tant qu'elle n'est pas utilisée.

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Virtual channel (network, atm)
A term to describe unidirectional flow of ATM cells between connecting (switching or end-user) points that share a common identifier number (VCI) A VC may traverse several virtual paths.
Each physical circuit in an ATM network is pre-configured with some number of virtual paths. Each virtual path may support many virtual channels. Neither VPs nor VCs are assigned any dedicated bandwidth. Bandwidth is allocated on demand by the network as users have traffic to transmit. (see VCC)

Voie virtuelle (réseau, atm)
Les stations ATM établissent entre elles pour communiquer des circuits virtuels de bout en bout. Un circuit virtuel donné est constitué d'une succession de couple VP/VC entre chaque commutateur traversé sur sa route depuis la source jusqu'à la destination. Portion de VP ou de VC utilisée pour établir une unique connexion entre deux stations terminales.

VCC

Virtual Channel Connection (atm)
Defined as a concatenation of virtual channel links.
Virtual channels in two or more sequential physical circuits can be concatenated to create an end-to-end connection, called a VCC. A VCC is a specific instance of a SVC or PVC. A VCC may traverse one end-to-end VPC or several sequential VPCs.

Connexion de Voie Virtuelle (atm)

VCI

Virtual Channel Identifier (atm)
The unique numerical tag used to identify every virtual channel across an ATM network, defined by a 16-bit field in the ATM cell header. (see VC, VCC, VP).

Identificateur de voie virtuelle (atm)
Champ numérique qui identifie de manière unique un canal virtuel (VC) à travers un réseau ATM et constitue ainsi une partie de l'adresse d'une trame. La longueur de ce champ est de 16 bits dans l'ent te de la cellule ATM.

VCL

Virtual Channel Link (network)
A means of unidirectional transports of ATM cells between the point where a VCI value is assigned and the point where that value is translated or removed.

VCPI

Virtual Control Program Interface
An alternative, and incompatible method for doing the same thing as DOS Protected Mode Interface (DPMI).

Spécification autorisant plusieurs programmes s'exécutant en mode réel à partager de la mémoire paginée.

VDSL: V Digital Subscriber Line (communications, protocol, network)
See also DSL.

VDU

Visual Display Unit (hardware)
(VDU, or "video terminal") A device incorporating a cathode ray tube (CRT) display, a keyboard and a serial port. A VDU usually also includes its own display electronics which store the received data and convert it into electrical waveforms to drive the CRT.
Early VDUs could only display characters in a single preset font, and these were confined to being layed out in a rectangular grid, reproducing the functionality of the paper-based teletypes they were designed to replace. Later models added graphics facilities but were still driven via serial communications, typically with several VDUs attached to a single multi-user computer. This contrasts with the much faster single bitmap displays integrated into most modern single-user personal computers and workstations.

Unité d'affichage, généralement terminal ou écran d'ordinateur.

VESA

Video Electronics Standards Association (body, standard)
An industry standards organisation created in 1989 or 1990 mostly(?) concerned with IBM compatible personal computers. The first standard it created was the 800 x 600 pixel Super VGA (SVGA) display and its software interface. It also defined the VESA Local Bus (VLB). See also PCI. association américaine regroupant les principaux constructeurs de cartes graphiques et de moniteurs. A défini les normes VESA pour les cartes graphiques

VF

Variance Factor
It is the CRM normalizedby the variance of the total cell rate over a given circuit.

VFast

28800bps, original (working) name for V.34 standard for modem. Most implementations were incompatible with each other. It is obsolete.

Protocole de communications d'un modem à 28800 bps développé par certains constructeurs en attente de la normalisation V.34.

VGA

Video Graphics Array (hardware)
A display standard for IBM PCs, with 640 x 480 pixels in 16 colours and a 4:3 aspect ratio. There is also a text mode with 720 x 400 pixels.
IBM technical references define the *product name* of their original VGA display board as "Video Graphics Array", in contrast to the preceding boards, the "Color Graphics Adapter" (CGA) and "Enhanced Graphics Adapter" (EGA).

Vidéopad

Vidéotex Packet Aseembler-Dissasembler (network)

Dispositif d'assemblage-désassemblage de paquets permettant au trafic provenant de terminaux vidéotex d'être transporter sur un réseau à commutation de paquets X25.

Videotex

An obsolete electronic service offering people the privilege of paying to read the weather on their television screens instead of having somebody read it to them for free while they brush their teeth. The idea bombed everywhere it wasn't government-subsidised, because by the time videotex was practical the installed base of personal computers could hook up to time-sharing services and do the things for which videotex might have been worthwhile better and cheaper. Videotex planners badly overestimated both the appeal of getting information from a computer and the cost of local intelligence at the user's end. Like the gorilla arm effect, this has been a cautionary tale to hackers ever since. See also vannevar.

Vidéotex
Technique de communication utilisant le réseau téléphonique pour transmettre des images ou des pages d'écran (en France le service Télétel).

VIM

Vendor Independant Messaging (communications,networking)
An electronic mail API promoted by an industry group headed by Lotus Development. VIM is a competitor to Microsoft's MAPI.

Interface de messagerie promue par Lotus. Le comité VIM comprend entre autres Lotus, Borland, Apple, Novell... Concurrent du Mapi de Microsoft.

Virus

(By analogy with biological viruses, via SF) A cracker program that searches out other programs and "infects" them by embedding a copy of itself in them, so that they become Trojan horses. When these programs are executed, the embedded virus is executed too, thus propagating the "infection". This normally happens invisibly to the user.

Unlike a worm, a virus cannot infect other computers without assistance. It is propagated by vectors such as humans trading programs with their friends (see SEX). The virus may do nothing but propagate itself and then allow the program to run normally. Usually, however, after propagating silently for a while, it starts doing things like writing "cute" messages on the terminal or playing strange tricks with the display (some viruses include display hacks). Many nasty viruses, written by particularly antisocial crackers, do irreversible damage, like deleting all the user's files.
In the 1990s, viruses have become a serious problem, especially among IBM PC and Macintosh users (the lack of security on these machines enables viruses to spread easily, even infecting the operating system). The production of special anti-virus software has become an industry, and a number of exaggerated media reports have caused outbreaks of near hysteria among users; many lusers tend to blame *everything* that doesn't work as they had expected on virus attacks. Accordingly, this sense of "virus" has passed into popular usage (where it is often incorrectly used to denote a worm or even a Trojan horse). See boot virus, phage. Compare back door. See also Unix conspiracy.

Programme qui possède la faculté de créer les répliques de lui-même dans un autre programme. Effets néfastes: messages intempestifs, ralentissement, pertes de données...

VLAN

Virtual Local Area Network
A network configuration in which users communicate using LAN protocols as if they were on the same physical LAN, but where they are in fact on physically separate LANs. Software and/or hardware mask the physical topology of the users and provide a logical topology which is more suitable to the users' requirements.

Réseau Local Virtuel

VML

Vector Markup Language (graphics)

Langage de Marquage Vectoriel (graphisme)
Format graphique qui a fusionné avec PGML (Precision Graphics Markup Language) pour donner la norme SVG.

Vocodeur

Vocoder (communications)
Voice coder, speech is encoded before transmission to reduce the number of bits required to represent speech.

Equipement ou composant électronique capable de décomposer un son en ses composantes fondamentales pour le numériser, le stocker et/ou le transmettre.

VOD

Video on Demand (communications)
A technology that enables the customer to remotely select and play a video, transmitted over communications links. A planned system using video compression to supply programs to viewers when requested, via ISDN or cable.

Vortal

Vertical Portal ( internet, intranet)
Vertical Industry Portal is a portal Web site that provides information and resources more specific in focus for a particular industry. Typical industry examples are medicine, automobiles, pets, beauty and health, computers and investments. Vortals are the Internet's way of catering to consumers' focused-environment preferences. Vortals typically provide news, research and statistics, discussions, newsletters, online tools, and many other services that educate users about a specific industry. As the Web becomes a standard tool for business, vortals will join and maybe replace general portal sites like AOL, Compuserve and Yahoo! as common gateways to the Internet.
Examples: Verticalnet.com and Internetcapital.com.

Vortail
portail Vertical ou de niche ou d'affinit�s.(internet, intranet)
N�ologisme d�signant les portails dits verticaux, destin�s aux professionnels.
Le terme " vertical " indique que les ressources sont accessibles via un moteur d�di� et par entr�es m�tiers ou secteurs.
Exemple de vortails:

R�f�rencement de ressources juridiques: FindLaw avec moteur de recherche " LawCrawler qui scrute le web � la recherche de sites web juridiques.
PinPoint.com, SearchButton, Electionsearch2000.org ,
BetterGetter, EoExchange (ex-Aeneid) disposent de leur propre robot d'indexation.

VP

Virtual Path
A term to describe a set of virtual channels (VCs) grouped together, between crosspoints (i.e. switches).
Each physical circuit in an ATM network is pre-configured with some number of virtual paths. Each virtual path may support many virtual channels. Neither VPs nor VCs are assigned any dedicated bandwidth. Virtual paths may be used to construct end-to-end connections, called VPCs.

Conduit Virtuel
VCI (Virtual Channel Identifier) et VPI (Virtual Path Identifier) : l'identité du canal virtuel et de la voie virtuelle. Ils représentent plusieurs champs des octets 1, 2, 3 et 4 de l'en-tête. On retrouve cette notion dans X.25.

VPC

Virtual Path Connection. (atm)
Virtual paths in two or more sequential physical circuits can be concatenated to create a logical connection, called a VPC. VPCs must be pre-configured. All Cells traversing VCs in a VPC are routed the same way
See VPI.

Connexion de Conduit Virtuel
Regroupement de VCC(Virtual Channel Connection).Voir VPI.

VPCI/VCI

Virtual Path Connection Identifier/Virtual Channel Identifier (network)
A combination of two numbers, one for identifying the VPand one for VCI.

VPDN

Virtual Private Data Network (network, public)

VPI

Virtual Path Identifier (atm)
The 8-bit number in an ATM UNI cell header or the 12-bit number in an ATM NNI or B-ICI cell header identifying the specific virtual path(VP) on which the cell is traversing on the current physical circuit. The ETSI version of ATM called it VCI VCI. A virtual connection established using only the VPI is known as a virtual path connection (VPC).

Identificateur de conduit virtuel
Adresse du chemin internoeud.

VPL

Virtual Path Link (network,atm)
The field in the ATM cell header that labels (identifies) a particular virtual path.

VPN

Virtual Private Network (network)
Network resources provided to users, on-demand, by public carriers such that the users view this partition of the network as a private network(customer-unique addressing, network management capabilities, dynamic reconfiguration, etc.).

A VPN can also be used using cryptology across Internet, each end of a connexion is controled by a firewall.

The network connection appears to the user as an end-to-end, nailed-up circuit without actually involving a permanent physical connection, as in the case of a leased line. The advantage of the VPNs over the dedicated private networks is that the former allow a dynamic allocation of network resources.

Réseau Privé Virtuel (RPV) (network, Internet)
Ressources réseau proposées à des utilisateurs, par un opérateur Télécom, de telle façon que les utilisateurs percoivent cette partition de résau comme un réseau privé (adressage client spécifique, outils d'administration, reconfiguration dynamique,etc.). La connexion réseau apparait à l'utilisateur comme un circuit de bout-en-bout, comme avec une ligne louée(LS) mais sans qu'existe pourtant de connexion physique. L'avantage principal du VPN est la possibilité d'allocation dynamique de ressources si la nécessité le demande.

Le concept de VPN a évolué avec l'avénement des autoroutes de l'information et en particulier Internet. Différentes solution sont proposées sur le marché, permettant en utilisant le cryptage des données, de constituer des VPN s'appuyant sur Internet. Entre plusieurs intranets isolés d'Internet et contrôlés par des gardes-barrières(firewall)peut ainsi être constitué un VPN constitué par des canaux cryptés.

VPT

Virtual Path Terminator (network)
A system that unbundles the Vcs of a VP for independent processing of each VC.

VRC

Vertical Redundancy Check (network)

Contrôle vertical de redondance. Désigne la parité appliquée à un mot et non pas à la suite des mots (parité longitudinale).

VRML

Virtual Reality Modeling Language (language)

Langage de description de scènes tridimentionnelles intégrant des liens "hypermédia".

VRU USA

Voice Response Unit (telephone)
Syn IVR(Interactive Voice Response).
Equipment that prompts callers to input information about their accounts or about the nature of their call. For example, a VRU might be a recording that instructs, "Please enter your account number using your touch-tone phone," or "If you would like to speak with a sales agent, please press one." The VRU feeds such information into the ACD so that calls are correctly routed. VRUs can also feed information to agents in the form of screen pops. VRUs are sometimes called Interactive Voice Response (IVR) units.

Unité de Réponse Vocale/ Répondeur Vocal Interactif (téléphonie)
Nom donné aux USA à un dispositif permettant d'orienter et d'analyser l'appel. Il informe et propose à l'appelant un menu de navigation. Ce système est complémentaire avec l'UCD (voir ci-dessus).
voir CTI, NLU.
Autre terme anglo-saxon: IVR(Interactive Voice Response).

VS/VD

Virtual Source / Virtual Destination (atm)

VSA

Virtual Scheduling Algotithm (atm)
GCRA ??equivalent algorithm used by ITU UPC and NPC specifications.

Algorithme identique à GCRA utilisé par les spécifications UIT de UPC et NPCNPC.

VSAT

Very Small Aperture Terminal (communications)
A kind of ground station used to contact a communications satellite such as INMARSAT.

Terminal d'émission-réception par satellite de petite dimension. Il permet d'échanger des données à bas ou moyens débits en utilisant une fraction étroite de la capacité totale du satellite.

VT

Virtual Tributary (network,atm)
A mechanism of capacity allocation in SONET that subdivides a synchronous payload envelope into lower-bit-rate envelopes within the SONET signal.

VTAM

Virtual Telecommunications Access Method
Access method IBM SNA architecture.

Méthode d'accès dans l'architecture SNA d'IBM permettant aux applications de faire appel à des ressources de télécommunication.

VTOA

Voice Telephony Over ATM (atm)
ATM Forum specification concerning voice telephony over ATM.

Spécification de l'ATM Forum qui traite de la téléphonie vocale sur ATM.

VTP

Virtual Terminal Protocol
OSI's remote terminal protocol.

Protocole de terminal virtuel. Sous-ensemble normalisé de la couche 7 (Application) de l'OSI destiné à rendre indépendant les applications du type de terminal utilisé.

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Last modified: 15 May 2000 <Philippe Molinié>

Base de connaissances en Télécommunication et Informatique Knowledge Database about Telecommunication

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Base de connaissances en Télécommunication et Informatique
Knowledge Database about Telecommunication