Out-of-band

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Out-of-band

Out-of-band (OOB) is a technical term with different uses in communication

Communication

Communication is commonly defined as "the imparting or interchange of thoughts, opinions, or information by speech, writing, or signs...",, 1: an act or instance of transmitting and 3 a: "a process by which information is exchanged between individuals through a common system of symbols, signs, or beha...
s and telecommunication

Telecommunication

Telecommunication is the assisted Transmission of Signal over a distance for the purpose of communication. In earlier times, this may have involved the use of smoke signals, Drum , Semaphore line, flag signals or heliograph....
. It refers to communications which occur outside of a previously established communications method or channel.

The use of the word "band" in "out-of-band" originates from the term as used in radio and other electronic communications

Band (radio)

A band is a small section of the electromagnetic spectrum of radio communication frequency, in which channel are usually used or set aside for the same purpose....
.

eneral language, "out-of-band" refers to communications which occur outside of a previously established communication method or channel.

Here are some very basic examples:

of-band communication is the exchange of call control information in a separate band from the data or voice stream, or on an entirely separate, dedicated channel (as in Common Channel Signaling

Common Channel Signaling

In telephony, Common Channel Signaling or in the US Common Channel Interoffice Signaling is the transmission of Signaling ing information on a separate channel to the data, and, more specifically, where that signaling channel controls multiple data channels....
).

a class="link1" onMouseover='showByLink("m1459940",this)' onMouseout='hide("m1459940")'href="http://www.absoluteastronomy.com/topics/Computer_network">computer network

Computer network

A computer network is a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network....
ing, out-of-band data (called "urgent data" in TCP

Transmission Control Protocol

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Encyclopedia

Out-of-band (OOB) is a technical term with different uses in communication

Communication

Telecommunication

Band (radio)

A band is a small section of the electromagnetic spectrum of radio communication frequency, in which channel are usually used or set aside for the same purpose....
.

General usage

In general language, "out-of-band" refers to communications which occur outside of a previously established communication method or channel.

Here are some very basic examples:

A person is involved in a discussion with a group of people. During the discussion, he decides that some information is best kept between himself and one other member of the group, exclusively, such as by whispering
Whisper

Whisper may refer to:* whispering, a form of vocalization...
-- whether for privacy
Privacy

Privacy is the ability of an individual or group to seclude themselves or information about themselves and thereby reveal themselves selectively....
reasons, or merely the need to avoid saturating the entire group with information they do not need. His communication with that individual may be considered out-of-band, relative to the group discussion.
A person is at his place of work, and he is communicating with someone outside of his work place (for example, by Internet
Internet

The Internet is a global network of interconnected computers, enabling users to share information along multiple channels. Typically, a computer that connects to the Internet can access information from a vast array of available server and other computers by moving information from them to the computer's local memory....
or telephone
Telephone

The telephone is a telecommunications device that is used to transmitter and receive electronically or digitally encoded sound between two or more people conversing....
, using his employer's computer
Personal computer

A personal computer is any general-purpose computer whose original sales price, size, and capabilities make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator....
or telephone equipment
Private branch exchange

A private branch exchange is a telephone exchange that serves a particular business or office, as opposed to one that a common carrier or telephone company operates for many businesses or for the general public....
). He decides that key parts of his conversation are best kept private from his employer, such as if he were discussing plans to change jobs. He would use his personal cell phone to transmit sensitive messages to, and receive related messages from, his external contact, in order to avoid use of his employer's phone or computer network
Computer network

A computer network is a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network....
. In this situation, his personal cell phone communications are considered out-of-band, relative to the main conversation.

Telecommunications

Out-of-band communication is the exchange of call control information in a separate band from the data or voice stream, or on an entirely separate, dedicated channel (as in Common Channel Signaling

Common Channel Signaling

Computing

In computer network

Computer network

Transmission Control Protocol

The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is so central that the entire suite is often referred to as "TCP/IP"....
) looks to the application like a separate stream of data from the main data stream. This can be useful for separating two different kinds of data. Note that just because it is called "urgent data" does not mean that it will be delivered any faster or with higher priority than data in the in-band data stream. Also beware that unlike the main data stream, the out-of-band data may be lost if the application cannot keep up with it.

In computer administration, out-of-band management refers to system console

System console

The system console, root console or simply console is the text entry and display device for system administration messages, particularly those from the BIOS or boot loader, the Kernel , from the init system and from the syslog....
access provided, even in the event of primary network subsystem (hard and/or software) failure. This can be done via a console server

Console server

A console server is a device or service that provides access to the system console of a computing device via networking technologies.Most commonly, a console server provides a number of serial ports, which are then connected to the serial ports of other equipment, such as servers, routers or switches....
or with a remote access card (RAC) which has its own processor, memory, battery, network connection, and access to the system bus.

The term "out-of-band" is sometimes confused with the term "out-of-bounds", which in computer programming

Computer programming

Computer programming is the process of writing, testing, debugging/troubleshooting, and maintaining the source code of computer programs. This source code is written in a programming language....
refers to values returned by a function that are not in its "natural" range of return values, but rather signal some kind of exception. Many C programming language

C (programming language)

C is a general-purpose computer programming language originally developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories to implement the Unix operating system....
functions that normally return a non-negative integer will return -1 to indicate failure (See also end-of-file

End-of-file

In computing, end-of-file, commonly abbreviated EOF, is a condition in a computer operating system where no more data can be read from a data source....
). It is actually a clear example of in-band signalling since it uses the same "channel" for control and data (In-band signaling

In-band signaling

In telecommunications, in-band signaling is the sending of metadata and signalling in the same band, on the same channel, as used for data....
is the opposite of out-of-band signaling and out-of-band signaling is one method of achieving network transparency

Transparency (telecommunication)

In telecommunications, transparency can refer to:#The property of an entity that allows another entity to pass thorough it without altering either of the entities....
).

In personal communications, methods other than e-mail (such as telephone

Telephone

The telephone is a telecommunications device that is used to transmitter and receive electronically or digitally encoded sound between two or more people conversing....
or snail-mail) are called "out-of-band".