Notice-board

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

A

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ADSL - Asymmetric Digital Subscriber Line

One of the four technologies of DSL type; it was designed with a wider transmission band for downstream (towards the user) than upstream (towards the connection provider). The downstream transmission speed is in the range of up to 9 Mb/s, while the upstream speed is 16-640 kb/s.

ATM - Asynchronous transfer mode

A high-speed transmission technology using the switching of fixed-length (53-byte) cells. The fixed length of cells allows fast processing in the hardware of switches during their transmission through the ATM network. 

B

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Bit

A binary symbol. Either 1 or 0. A byte consists of 8 bits.

bps, b/s (bits per second)

A number of bits transmitted or received per second.

BRI – Basic rate Interface

An ISDN BRI interface allows a speed of up to 128 Kbit/s, consists of two B-channels, each having a speed of 64 Kbit/s, and a D-channel of a speed of 16 Kbit/s. B-channels transmit user data and voice. D-channel is a service channel designed for transmission operators.

Broadband

A characteristic of any network transmitting multiple and separate network signals in a single line. Thus, it allows the coexistence of several networks in one physical line (cable). Different networks do not disturb each other because their communication runs on different frequencies.

Byte

A unit of information comprising eight bits. A byte is the smallest addressable element of a computer memory. Memory capacity is given in bytes. 

C

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Client/Server - Klient/Server

A computer system architecture. The server usually maintains data and ensures operation with them. The client communicates with the server through queries, requests and answers.

CLIP - Calling Line Identification Presentation

The caller’s identification. It enables the called subscriber to determine the calling subscriber’s identification.

CLIR - Calling Line Identification Restriction

Identification display barrier. The display of the calling line is barred so that the called person cannot view it.

CODEC - Coder-decoder

A device typically using pulse code modulation for the conversion of analog signals to a digital stream of bits and vice versa.

Cookie

Information sent from a WEB server to a browser for storing specific information (e.g. on individual setting, which can be used when another request is addressed to the same WEB server).
 
CS

Carrier Selection is the selection of a provider through a short prefix for individual calls.

CPS

Carrier PreSelection is a fixed selection of a prefix in the network of the access provider (ČESKÝ TELECOM, a.s.) designed for accessing the services of the selected telecommunication operator (České radiokomunikace) without the need of the caller’s additional actions while making every call. 

D

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DSL - Digital Subscriber Line

A network technology allowing high-speed transmissions through standard copper wires at short distances lines; four types of DSL technology are used: ADSL, HDSL, SDSL and VDSL. Their common feature is the use of modems at the end of the line and a possible transmission of a voice channel.

Domain Name

Jméno domény

DNS (Domain Name System)

A distributed database for the translation of domain names to IP addresses of network nodes on the Internet (e.g. the translation of the address www.inway.cz to the IP address 222.111.128.15).

DNS (Name) Server

A DNS (Name) Server maintains information for the translation of computer names to IP addresses (or for a reverse translation). A Name Server always controls a portion of the space of names of all computers. This portion is called zone. A zone comprises a domain or its part. With the help of an NS type sentence in its configuration, a Name Server can delegate the control of a sub-domain to a lower-level Name Server.

DSLAM - Digital Subscriber Line Access Multiplexer

A device allowing the multiplexing of transmissions by DSL technology through standard copper wires. 

E

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E1

A digital transmission scheme for communication lines with the speed of 2.048 Mb/s, used in Europe. It is analogous to the T1 scheme used in the US.

E-commerce - Elektronický obchod

Business transactions and communication performed through computers and the computer network, including the Internet (WAN networks in general). It comprises money transfers in digital form, although it is not limited to this only – it also applies to marketing, videoconferencing and other functions serving business purposes.

E-mail - Elektronická pošta

A complex of programs and system equipment for electronic (network) communication among computer users. It is analogous to the classical mail system but with all the advantages and disadvantages of electronic data processing and transmission.

Electronic Mail Address - Adresa elektronické pošty

Features identifying the addressee or recipient of a message sent by electronic mail. It consists of two parts: the user’s name and the name defining the computer IP address; between these parts there is an @ sign. Thus, the address novak@inway.cz means that novak is the user’s name, inway.cz is this user’s address in the Internet network.

Ethernet

A transmission technology of local area networks (LAN), developed by the company Xerox in 1976. The original transmission speed was 10 Mb/s, today it is 100 Mb/s (Fast Ethernet) and 1000 Mb/s (Gigabit Ethernet) as well. It uses logical bus topology, the CSMA/CD access method and a wide range of cables. It is defined by a set of IEEE 802.3  standards.

Ethernet address

A unique number assigned to each Ethernet network adapter. It is a 48-bit number identifying a specific network card.

Euro-ISDN

An ISDN standard for commercial applications in Europe. 

F

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Fast Ethernet

A specification of the Ethernet network with the transmission speed of 100 Mb/s, defined by the IEEE 802.3u specification. It uses the same framework format and access method as the standard Ethernet. The use of different transmission media (UTP cables, optical cables) is determined by the specifications 100BaseTX, 100BaseT4 and 100BaseFX.

Firewall

A system used for the protection of one network again unauthorized access from another network (e.g. LAN protection against access from the Internet). The system can be implemented using software, hardware or a combination of both.

Frame Relay

A transmission network technology working with the switching of frameworks (data link layer) of variable length. It uses a configuration of virtual circuits between interconnected devices and the HDCL standard for framework transmission. Owing to its higher efficiency, it replaces X.25 networks.

FTP server

FTP Server is used for the storage, exchange and download of files for web presentations with the help of the FTP protocol.

G

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Gateway

An interface for data transmission between applications/protocols. It endeavors to overcome differences between the actual interfaces of both applications. Thanks to the gateway, it is possible to use one network as a transparent connection between two networks with completely different parameters. 

H

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Hardware

Tangible technical means facilitating or extending operations of computer systems. It consists of a computer, its components (memory, motherboard, additional cards, etc.), printers, networks and other devices.

Helpdesk

A nonstop division of technical support to customers.

HTML - Hypertext Markup Language

A simple language for formatting hypertext documents, using special signs, determining how individual parts of a document are to be interpreted by a browser (www browser).

HTTP - Hypertext Transfer Protocol (HTTP)

A protocol used by WWW servers and WWW browsers for transmitting files on the Internet.

I

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Interface

1. A connection between two systems or devices. 2. In the routing terminology it represents a network connection. 3. In telephony it represents a shared interface defined by physical and signal characteristics. 4. An interface between adjacent layers of an OSI model.

Internet

The biggest global network interconnecting a continuously growing number of computers all over the world. It developed from a military project of the US Army; its biggest development started in the 1st half of the 1990s by its commercialization.

Intranet

An internal corporate network that uses the same protocols and mechanisms as the Internet.

IP - Internet Protocol

A network protocol from the set of TCP/IP protocols, working on the third network layer according to the OSI model, and ensuring the transmission of a packet through a service without establishing connection (version 4, IPv4). IP protocol is defined in RFC 791.

IP Address

The address of a computer in the network using an IP protocol. It comprises four 8-bit digits separated by dots, i.e. it can be e.g. 222.125.125.255. The IP address uniquely identifies a computer in the  worldwide Internet.

ISP - Internet Service Provider

A company providing access to the Internet to other subjects (companies or individuals).

ISDN - Integrated Services Digital Network

A communication technology for the transmission of voice and data information.

L

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LAN - Local Area Network

A group of computers and other equipment interconnected by a communication link in a relatively small geographic area (up to several thousands meters), facilitating their mutual communication. LAN standards specify cabling and signaling on the physical and connection level of the OSI model. 

M

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Mail Server

A Mail Server serves for the exchange of electronic mail between the sender and the addressee. In case of the connection of a corporate LAN, a Mail Server is used in the internal exchange of electronic mail and, at the same time, for the exchange of electronic mail with the other subjects through the Internet.

MSN - Multiple Subscriber Number

A service available to BRI connections only. It allows the assignment of up to eight telephone numbers to such a line.

N

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Number Portability

A service enabling a subscriber to transfer telephone numbers from one telecommunication provider to another.

O

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Optical Fiber

A glass or plastic fiber carrying a light that transmits a data signal. 

P

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Packet

An information unit transmitted as a whole between two devices. In networks with packet switching it is a unit of fixed maximum size that consists of binary numbers representing useful data, heading and footing, bearing control information.

PBX - Private Branch exchange

Non-public corporate telephone exchange.

PCM - Pulse Code Modulation

A transmission technology in which an analog signal is sampled into a fixed number of bits in regular intervals and transmitted in a coded binary form.

POP3

A protocol allowing a client computer to read mail from the mail server (POP3) through a temporary connection, usually through the TCP/IP protocol.

PRI - Primary Rate Interface

An ISDN technology transmission channel comprising one D channel having the capacity of 64 Kb/s, and 23 (T1) or 30 (E1) B channels for voice or data.

PSTN - Public Switched Telephony Network

A general term describing different telephone networks and their services. Sometimes it is also called POTS.

Q

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QoS - Quality of Service

Terminal equipment can require a specific transmission quality – Quality of Service (QoS). Individual types of transmission are different and they frequently have contradictory requirements. Real-time voice and video transmission will require a defined delay with a minimum dispersion, which will not do without the warranty of a certain minimum agreed width of the transmission band and, at the same time, it excludes the use of large buffer memories. On the other hand, data transmissions do not have strict requirements for a minimum transmission band, cell delay and its dispersion, and they require large buffer memories for an efficient transmission. These different requirements for quality parameters of the transmission of ATM connection were solved through the introduction and definition of several classes of services. At present, four types of classes of services are defined; they are labeled with letters A, B, C and D, or with names expressing the relationship between a given class of services and the transmission speed. 

R

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Router

A device interconnecting two networks using the same network protocol. The routing decision comes from the information of the third layer (network layer) of the OSI model. 

S

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Splitter

A device used in ADSL technology for splitting or uniting call and data frequency bands 

T

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TCP - Transmission Control Protocol

The most common transmission protocol used in IP networks, allowing reliable, fully duplex transmissions with establishing connections.

TCP/IP - Transmission Control Protocol/Internet Protocol

A set of protocols developed in the ARPA (Advanced Research Projects Agency) for the Internet networks in the early 1970s. It comprises TCP as the primary transport protocol and IP as the network layer protocol.

U

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User Name

A name under which a user gets connected to a protected user system. 

V

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VoD - Video on Demand

A service that enables customers to download different video/audio recordings from an Internet server through a broadband network and to replay them later.

VoIP - Voice over IP

A technology serving for voice transmission. The voice is first digitized, then compressed, packed into packets and transmitted through the IP network.

W

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WAN - Wide Area Network

An extensive data communication network covering a wide geographic area and using connections provided by public providers of transmission services.

WWW server

A computer located in the Internet network that provides a WWW service, i.e. it sends WWW pages to user upon requests placed by their programs, and WWW pages are displayed in these programs. In order to work correctly, a WWW server must be connected to the Internet on a permanent basis and be functional without interruption.