when data is transmitted (usually data is 8 bit wide) some control bits are added to this data like checksum bit (parity). For IP protocols the structure is a little more complex.


----- link: http://encyclopedia.thefreedictionary.com/Overhead bit ---

In data transmission and telecommunication, overhead bits are nondata bits necessary for transmission (usually as part of headers, checksums, and such).
Data transmission is the conveyance of any kind of information from one space to another. Historically this could be done by courier, a chain of bonfires or semaphores, and later by Morse code over copper wires.
..... Click the link for more information.
Telecommunication is the transmission of signals over a distance for the purpose of communication. In modern times, this process typically involves the sending of electromagnetic waves by electronic transmitters, but in earlier times telecommunication may have involved the use of
..... Click the link for more information.
checksum is a form of redundancy check, a simple way to protect the integrity of data by detecting errors in data that are sent through space (telecommunications) or time (storage).
..... Click the link for more information.

This article is copied from an article on Wikipedia® - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the Wikipedia® encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.